Emerging Nanomaterials: Opportunities and Challenges in Forestry Sectors 3031173775, 9783031173776

Citation preview

Hamid R. Taghiyari Jeffrey J. Morrell Azamal Husen   Editors

Emerging Nanomaterials Opportunities and Challenges in Forestry Sectors

Emerging Nanomaterials

Hamid R. Taghiyari  •  Jeffrey J. Morrell Azamal Husen Editors

Emerging Nanomaterials Opportunities and Challenges in Forestry Sectors

Editors Hamid R. Taghiyari Department of Wood Science and Technology Faculty of Materials Engineering and New Technologies, Shahid Rajaee Teacher Training University Tehran, Iran

Jeffrey J. Morrell National Centre of Timber Durability & Design Life University of the Sunshine Coast Brisbane, Australia

Azamal Husen Wolaita Sodo University Wolaita, Ethiopia

ISBN 978-3-031-17377-6    ISBN 978-3-031-17378-3 (eBook) https://doi.org/10.1007/978-3-031-17378-3 © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

Preface

Bio-based materials, including those containing wood, will become increasingly important as we move to a bio-based economy. Among other attributes, two are of vital importance: firstly, they are renewable, thus, with proper management, a sustainable development can be established on their basis; secondly, bio-based materials can be more environmentally friendly. While wood is an amazing material, it still has negative attributes and drawbacks that can affect performance, including dimensional instability when wetted, vulnerability to fire and high temperatures, and susceptibility to biodeterioration. A variety of treatments have been developed to overcome these weaknesses. Among the most exciting of these treatments are nanomaterials. These materials have some exceptionally attractive properties for improving timber performance and have been the subject of intensive research over the past decade. There is a tremendous need for a single comprehensive source of information on this rapidly emerging subject with tremendous potential to enhance the performance of a variety of bio-based materials. This book contains 10 chapters, each compiled by different authors who are considered top researchers in their respective fields. The chapters begin with some basic background on nanomaterials and their synthesis, then explore different areas for potential applications, and then conclude with a review of the emerging questions about nanomaterials safety. The book is designed to provide the latest information and know-how on application and utilization of different nanomaterials to improve the properties of wood and woodbased composite panels. The contents cover some main topics in the industry from improvement in physical and mechanical properties to increased resistance to biodegradation (including fungi and insects) to the development of wood-plastic

v

vi

Preface

composites (WPCs) or emergence of transparent wood. It also covers the use of nanomaterials to improve the performance of paints and finishes used for forest products. The book provides a single location for those interested in the field to better understand the potential of these materials. Tehran, Iran  Hamid R. Taghiyari Brisbane, QLD, Australia  Jeffrey J. Morrell Wolaita, Ethiopia Azamal Husen

Contents

Emerging Nanomaterials for Forestry and Associated Sectors: An Overview ����������������������������������������������������������������������������������������������������    1 Hamid R. Taghiyari, Jeffrey J. Morrell, and Azamal Husen Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview ����������������������������������������������������������������������������������������������������   25 Petar Antov, Seng Hua Lee, Muhammad Adly Rahandi Lubis, and Sumit Manohar Yadav Nanomaterials to Improve Fire Properties in Wood and Wood-Based Composite Panels ��������������������������������������������������������������   65 Jakub Kawalerczyk, Joanna Walkiewicz, Dorota Dziurka, and Radosław Mirski  Wood Plastic Composites (WPCs): Applications of Nanomaterials������������   97 Mustafa Zor, Fatih Mengeloğlu, Deniz Aydemir, Ferhat Şen, Engin Kocatürk, Zeki Candan, and Orhan Ozcelik Nanomaterials to Improve Properties in Wood-Based Composite Panels ��������������������������������������������������������������������������������������������  135 Viktor Savov  Nanomaterials to Improve the Strength of Wooden Joints��������������������������  155 Roger Moya and Carolina Tenorio  Application of Nanomaterials for Wood Protection��������������������������������������  179 Tumirah Khadiran, Latifah Jasmani, and Rafeadah Rusli  Nanocellulose in Paper and Board Coating��������������������������������������������������  197 Ayhan Tozluoglu, Saim Ates, Ekrem Durmaz, Selva Sertkaya, Recai Arslan, Orhan Ozcelik, and Zeki Candan

vii

viii

Contents

 Green Materials for Radiation Shielding: An Overview������������������������������  299 Ertuğrul Demir, Zeki Candan, Ning Yan, Araz Rajabi-Abhari, Özlem Vural, Matlab Mirzayev, Evgeni Popov, S. İpek Karaaslan, and Bülent Büyük Formaldehyde Emissions from Wood-­Based Composites: Effects of Nanomaterials ��������������������������������������������������������������������������������  337 Charalampos Lykidis Index������������������������������������������������������������������������������������������������������������������  361

About the Editors

Hamid R. Taghiyari’s,  main area of expertise is fluid flow and permeability in wood and wood-based composites, wood modification techniques, and utilization of nanomaterials in wood and wood-based composites. He has intensively worked on the effects of different nanomaterials on properties of solid wood (different species), and composite panels as well, over the last two decades. He began work with nanometals (including silver, copper, zinc oxide); soon, he turned to minerals as they are more abundant and cheaper, and cause lesser environmental hazards. The results of his studies have been published in a wide range of academic journals. He had the privilege of mentoring more than 40 postgraduate students, mainly on utilization of nanomaterials to improve different properties in solid wood, as well wood-based composite panels, including physical and mechanical properties, fire-retardant properties, and biological durability against wood-­deteriorating fungi and insects. Jeffrey J. Morrell,  holds BSc and PhD degrees form the State University of New  York, College of Environmental Science and Forestry, in forest biology and forest pathology and mycology, respectively, as well as an MSc from Pennsylvania State University in plant pathology (nematology). He has over 40 years of experience in the field of wood science, concentrating on durability. His research has spanned the field from understanding the fungal sequences during decay to the use of various chemicals to minimize fungal attack and ultimately to the movement and fate of preservatives, especially in aquatic environments. He has been fortunate to mentor more than 50 postgraduate stuix

x

About the Editors

dents. He is currently director of the National Centre for Timber Durability and Design Life at the University of the Sunshine Coast in Brisbane, Australia, and is actively engaged in research related to enhancing the performance of cellulosic materials. Azamal Husen,  currently a foreign delegate at Wolaita Sodo University, Wolaita, Ethiopia, has served the University of Gondar, Ethiopia, as Full Professor of Biology, and worked there as the coordinator of the MSc program and as the head of the Department of Biology. Earlier, he was a visiting faculty at the Forest Research Institute and the Doon College of Agriculture and Forest in Dehra Dun, India. His research and teaching experience of 20 years involves studies of biogenic nanomaterial fabrication and application; plant responses to nanomaterials; plant adaptation to harsh environments at the physiological, biochemical, and molecular levels; herbal medicine; and clonal propagation for improvement of tree species. He has conducted several research projects sponsored by various funding agencies, including the World Bank (FREEP), the National Agricultural Technology Project (NATP), the Indian Council of Agriculture Research (ICAR), the Indian Council of Forest Research Education (ICFRE), and the Japan Bank for International Cooperation (JBIC). He received four fellowships from India and a recognition award from the University of Gondar, Ethiopia, for excellent teaching, research, and community service. Dr. Husen has been on the editorial boards and the panel of reviewers of several reputed journals published by Elsevier, Frontiers Media, Taylor & Francis, Springer Nature, RSC, Oxford University Press, Sciendo, The Royal Society, CSIRO, PLOS, MDPI, and John Wiley & Sons. He is on the advisory board of Cambridge Scholars Publishing, UK.  Dr. Husen is a fellow of the Plantae Group of the American Society of Plant Biologists, and a member of the International Society of Root Research, Asian Council of Science Editors, and INPST. He has more than 175 publications to his credit. He is editor-in-chief of the American Journal of Plant Physiology, and a series editor of Exploring Medicinal Plants (Taylor & Francis Group, USA); Plant Biology, Sustainability, and Climate Change (Elsevier, USA); and Smart Nanomaterials Technology (Springer Nature, Singapore).

Emerging Nanomaterials for Forestry and Associated Sectors: An Overview Hamid R. Taghiyari, Jeffrey J. Morrell, and Azamal Husen

Contents 1  Introduction 2  Biodegradability of Wood 3  Physical and Mechanical Properties 4  Wood Coatings 5  Fire Retardants 6  Smart Windows 7  Transparent Wood 8  Nanomaterials: Risk Assessment 9  Conclusion References

 2  3  5  8  10  14  15  15  16  16

H. R. Taghiyari (*) Department of Wood Science and Technology, Faculty of Materials Engineering and New Technologies, Shahid Rajaee Teacher Training University, Tehran, Iran e-mail: [email protected] J. J. Morrell National Center for Timber Durability and Design Life, University of Sunshine Coast, Brisbane, Australia A. Husen Wolaita Sodo University, Wolaita, Ethiopia © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 H. R. Taghiyari et al. (eds.), Emerging Nanomaterials, https://doi.org/10.1007/978-3-031-17378-3_1

1

2

H. R. Taghiyari et al.

1 Introduction Nanotechnology involves the use of materials with very small dimensions (1–100 nanometers). At this infinitesimally small dimension, properties (physical, chemical, and even biological) of materials may fundamentally change. For instance, conductivity of some metals and semiconductors can be substantially improved (Li 2012). The term “nanotechnology” was first coined by Norio Taniguchi (Taniguchi et al. 1974). While he originally used this term to describe semiconductors, it was broadened to cover a wide range of materials and composites including molecular nanotechnology, carbon nanotubes, biomimetic nanotechnology, and a variety of experimental advancements on nanoindentation, nanolithography, atomic force microscopy (AFM), and scanning tunneling microscopy (STM). Nanotechnology is a broad multidisciplinary field of research that has already provided new capabilities for a wide range of materials and composites. Developing materials incorporating nanoscale particles has the potential to support the creation of entire new industries. Some visionary scientists have even suggested that the Nano Age will rival the importance of the Stone, Bronze, and Iron Ages and trigger a new industrial revolution. While subject to debate, nanomaterials do create a host of opportunities for product development including the creation of new wood-based materials. Wood is a versatile renewable material used for a myriad of applications and has played a major role in human development (Bal 2016; Daly-Hassan et  al. 2014; Verhaegen et  al. 2014; Lekha et  al. 2016; Souza et  al. 2018). Wood has gained renewed importance because of its carbon neutrality compared with nonrenewable materials such as steel or concrete. However, wood also has some major limitations including its tendency to shrink and swell with moisture changes and its susceptibility to biodegradation. Nanotechnology creates new options for upgrading wood properties including the development of new bio-resins that increase the ability to use small diameter logs and other lignocellulosic materials (Doost-hoseini et al. 2014; Mantanis et al. 2014; Hubbe et al. 2015; Li et al. 2016, 2017; Jiang et al. 2016; Taghiyari et al. 2016, 2019; Tajvidi et al. 2016; Wang et al. 2016a, b; Fu 2018; Majidi et al. 2019; Papadopoulos and Hill 2002; Papadopoulos 2009, 2021; Papadopoulos et al. 2020; Höglund et al. 2021; Papadopoulos 2009, 2021; Réh et al. 2019; Savov et al. 2019; Antov et al. 2020a, b, c, d, 2021a, b, c; Pizzi et al. 2020; Taghiyari et al. 2020a, b, c, 2021a; Aristri et al. 2021; Bekhta et al. 2021; Ninikas et al. 2021). Nanomaterials are often added to improve the properties of coatings, biocides, resins, polymer composites, and reinforced wood-based materials (Sandberg 2016). Nanomaterials can also be derived from the cellulose, lignin, and extractive components in wood allowing us to create new materials from our existing resources. This chapter reviews the main areas where nanomaterials can be used to improve the properties of wood and wood-based composites and explores areas for further exploration.

Emerging Nanomaterials for Forestry and Associated Sectors: An Overview

3

2 Biodegradability of Wood Wood is a biological material that can be degraded by a range of organisms adapted to utilize one or more of its polymers (bacteria, fungi, insects, and even marine borers) (Lykidis et al. 2013, 2016, 2018). However, properly designed and maintained structures may last for many centuries, even millennia, as evidenced by the wood elements found in many Egyptian pyramids. Most wood degrading organisms have four basic requirements including a food source, oxygen, adequate temperature, and, most importantly, free water (i.e., wood moisture contents >~30% oven dry weight basis). It is difficult to control temperature or oxygen levels, so most wood protection strategies either design to exclude moisture or, where that is not possible, modify the wood chemically. Most timber in buildings is used in applications designed to exclude moisture, thereby limiting the risk of attack, but a variety of preservation strategies have been developed where this is not possible (Milton 1995; Schmidt 2006, 2007; Schmidt et al. 2012). Simple brushing or dipping in a toxic chemical can protect wood in some applications, but more severe exposures require that the wood be impregnated with preservatives using combinations of vacuum and pressure to drive the chemical more deeply into the wood to create a protective envelope. Alternatively, the wood can be chemically modified to render it less susceptible to water uptake or less recognizable to the wood degrading enzymes (Sandberg et al. 2017; Bayani et al. 2019a, b; Xu et al. 2019; Sandak and Sandak 2021; Spear et al. 2021). Wood can also be heated or thermally modified to render it less able to sorb moisture, and this approach is widely used for non-soil contact exposures in Europe (Hill 2006; Tjeerdsma et al. 1998; Tjeerdsma and Militz 2005; Esteves et al. 2008; Borrega and Karenlampi 2010; Taghiyari 2013; Taghiyari and Moradi Malek 2014; Bayani et al. 2019a, b; Esmailpour et al. 2019a; Taghiyari and Schmidt 2014; Taghiyari et al. 2014a, b; Sandberg et al. 2017). Thermal modification can be further enhanced by addition of metal and mineral nanomaterials to improve thermal conductivity and enhance the thermal modification process (Taghiyari et al. 2015; Taghiyari and Avramidis 2019). Nanomaterials have a number of possible roles in wood protection. Nano-metals and nano-minerals can enhance heat transfer during the production of wood-based composites, thereby reducing pressing times. Nano-copper and nano-silver also have excellent fungicidal and antibacterial properties (Taghiyari et al. 2014a, b, c, Table 1  Mass losses (%) caused by exposing medium-density fiberboard (MDF) and particleboard (PB) specimens to A. vaillantii for 4 months Weight loss (%) Wood 100% Type of composite NW (0%) NW (10%) MDF >26 >2.5 PB >37 >2.5

Wood (95%) + CF (5%) NW (0%) NW (10%) >14.7 >4.5 >22.5 >4.5

NW nano-wollastonite content, CF chicken feather content

Wood (90%) + CF (10%) NW (0%) NW (10%) >25 >3 >21 >2.5

4

H. R. Taghiyari et al.

2019). Nano-wollastonite (NW) enhances resin curing, acts as a reinforcing agent in the resin, and has slight effects on resistant to biological degradation (Lykidis et al. 2013; Mantanis et al. 2014; Taghiyari et al. 2014a, b, c). It was reported that addition of 10% NW to UF resin (based on the dry weight of wood) significantly increased resistance to Antrodia vaillantii in both composite types (MDF and particleboard) (Table  1) (Taghiyari et  al. 2014b, c; Taghiyari and Schmidt 2014). Nanoparticles have a slight advantage compared with conventional solubilized preservatives in terms of their ability to move into wood through the cell pits, but penetration is still limited by cell wall pore size. As a result, nano-metals are unlikely to completely overcome the inherent resistance to fluid flow posed by the heartwood, but they create the potential for delivering more active ingredient into the wood that can slowly solubilize to provide a reservoir for longer-term protection (Clausen 2012; Mattos et al. 2017). The potential for using nano-copper for wood treatment was recognized by a number of researchers (Civardi et  al. 2016; Malviya and Chattopadhyay 2015; Thandavan et  al. 2015; Geetha Devi and SakthiVelu 2016; Hong et  al. 2016; Jeevanandam et al. 2016; Poletti Papi et al. 2017). Traditionally, copper-based preservatives are dissolved in water in either acidic or basic formulations. The earliest and most widely used of these systems was chromated copper arsenate (CCA), which used chromic acid to solubilize the copper. Restrictions on CCA use led to the substitution of amine-based systems that used either ammonia or amine to solubilize the copper. However, these systems were more costly and corrosive. Development of micronized systems whereby copper carbonate was ground to a fine powder that could be suspended in water reduced the need for costly cosolvents. Nano-copper further advances this approach, using smaller copper particles that have the potential to move more deeply into the wood. An as yet unexplored added attribute is their lower overall water solubility, which reduces the potential for migration of preservative from the wood and into the surrounding environment and may also have advantages with regard to fastener corrosion (Freeman and Mclntyre 2013; Kartal et al. 2014; Xue et al. 2014). Particle size has critical effects on the ability of the metal to penetrate into the wood cell wall, and copper nanoparticles should have an advantage over other copper particulate systems (Jin et al. 2008). It is unclear if the enhanced mobility translates into higher efficacy, although nano-zinc oxide has been reported to effectively protect Paulownia against Trametes versicolor (Akhtari et  al. 2012; Akhtari and Ganjipour 2013) and nano-copper appears to be more effective against termites (Akhtari and Nicholas 2013). The use of nanoparticles in solid wood treatment is constrained by the need to use conventional delivery processes. Nanoparticle use in composites offers a number of delivery options including resin addition, pretreatment of wood particles, or simple inclusion of nanoparticles in the furnish prior to pressing. Addition of nano-­ silver or nano-copper into liquid urea formaldehyde resin that was subsequently sprayed on the particles improved decay resistance of commercially produced particleboard (Gazvin Industrial Complex, Gazvin, Iran) (Taghiyari et  al. 2014a; Palanti et al. 2012; Taghiyari et al. 2014a).

Emerging Nanomaterials for Forestry and Associated Sectors: An Overview

5

Nanomaterials have also been evaluated for termite protection with mixed results (Bayatkashkoli et al. 2016; Mantanis et al. 2014). For example, zinc-based compounds inhibited termite feeding, while nano-copper compounds were less effective possibly because the levels employed were too low (Mantanis et al. 2014). Nano-­ metals are potentially effective but expensive to produce. Nano-minerals represent more economical materials. Wollastonite is an inosilicate mineral (CaSiO3) with good thermal conductivity and fungicidal properties (Aitken 2010; Karimi et  al. 2013; Taghiyari et al. 2013a, b; Taghiyari 2014; Taghiyari et al. 2018a, b; Taghiyari et al. 2019). Nano-wollastonite enhanced the decay resistance (Karimi et al. 2013; Taghiyari et  al. 2014b, c) and has excellent toxicological properties to nontarget organisms (Huuskonen et  al. 1983a, b). It is also widely available globally. Wollastonite has also been explored as a reinforcing additive in resins and adhesives, improving various physical and mechanical properties in wood-based composites (Taghiyari and Nouri 2015; Taghiyari and Sarvari Samadi 2016; Taghiyari et al. 2021b, c; Hassani et al. 2019; Taghiyari et al. 2020d, e). In addition to the use of nanoparticles in traditional wood-base composites, there is evidence that addition of nano-clay reduced water uptake while limiting fungal attack in wood-based composites (Taghiyari et al. 2020a; Bari et al. 2015, 2017). Metal and mineral nanoparticles have also been used to improve biological resistance of solid wood species and wood-based composites (Mora-Huertas et al. 2010; Lee and Feijen 2012). Polymeric nano-carriers, including encapsulated materials, were used to transfer active ingredients deep into wood (Martínez Rivas et al. 2017; Khoee et al. 2018). The results indicate that nonmetals and minerals have the potential to improve both physical properties and resistance to biological degradation of solid timber and wood-based composites and merit much further study.

3 Physical and Mechanical Properties The numerous hydroxyl groups render wood susceptible to water and vapor absorption leading to swelling that can cause permanent deformation (Figueroa et  al. 2012). A number of methods have been developed to minimize these processes. Nanomaterials have also been explored for this purpose especially for enhancing heat transfer to improve the efficiency of thermal modification (Taghiyari et  al. 2011, 2020b; Bayani et  al. 2019a, b). Wood specimens impregnated with nano-­ silver or nano-copper before being thermally modified had better mechanical properties in comparison with specimens with no initial impregnation possibly because the metals enhanced thermal transfer. Nano-silver (NS) or nano-copper (NC) addition was associated with significantly reduced particleboard press times, leading to increased production rates (Taghiyari et al. 2011; Taghiyari and Farajpour Bibalan 2013). It was reported that addition of 150 ml NS and NC in UF resin which was sprayed on chips decreased the press time by 10.9% and 5.7%, respectively (Table 2). Physical and mechanical properties of

6

H. R. Taghiyari et al.

Table 2  Hot-press times (in second) in control particleboards and particleboards with addition of 100  ml and 150  ml nano-silver and nano-copper suspension based on each kilogram of wood particles (dry weight basis) (Taghiyari et al. 2011; Taghiyari and Farajpour Bibalan 2013) Type of particleboard produced Nano-silver-added particleboards Nano-copper-added particleboards

Hot-press time (second) Control panels 100 ml 202.5 180.5 175 165

150 ml 181 169

Fig. 1  Schematic representation of the apparatus used for the measurement of thermal conductivity. (Taghiyari et al. 2017, 2020f)

NS- or NC-treated panels were also significantly improved, but excess addition of either metal was associated with reduced panel properties, likely because the metals enhanced heat transfer to the extent that resin cure was affected. Nano-­aluminum and nano-zinc oxide have also been investigated for their effects on wood-based composite panels suggesting that there is considerable potential for enhancing both production and physical properties through addition of nano-metals (Bak et  al. 2012; Mantanis et al. 2014; Lykidis et al. 2016; Harandi et al. 2016; Nair et al. 2017). While nano-metals have promise for both accelerating resin cure and improving panel properties, they can be costly. This has led to interest in less costly minerals as substitutes such as wollastonite, different clays, and sepiolite. These materials are easily mixed in resins. Wollastonite has been used as a reinforcing additive in resins and adhesives, improving various physical and mechanical properties in particleboards, medium-density fiberboards, and oriented-strand boards (Taghiyari and Nouri 2015; Taghiyari and Sarvari Samadi 2016; Hassani et al. 2019; Savov and Antov 2020). Thermal conductivity of sepiolite-reinforced UF resin in oriented strand lumber was measured using an apparatus designed and built based on

Emerging Nanomaterials for Forestry and Associated Sectors: An Overview

7

Fig. 2  SEM image showing sepiolite nanostrands. (Taghiyari et al. 2020f)

Fourier’s Law for heat conduction (Fig.  1). Calculation of thermal coefficients revealed an increases of 36% and 40% in thermal conductivity in lumber with 8% and 10% resin, respectively (Taghiyari et al. 2020f). The increase was attributed to the even dispersion of sepiolite nanostrands in UF resin (Fig. 2), acting both as a reinforcing agent in the resin and improving conductivity coefficient. Density functional theory (DFT) analysis has shown that wollastonite has sufficient adsorption energy to interact with cellulose and hemicelluloses (Taghiyari et  al. 2016, 2020b, c). The optimal adsorption distance of 1.7  Å and adsorption energy of −6.6 eV also suggest that wollastonite could be used as the main binder in composite panels. However, MDF panels produced using wollastonite as the binder with no resin had good mechanical properties but performed poorly in terms of water absorption and thickness swell (Taghiyari et al. 2020d). The poor performance was attributed to the ability of water molecules (with hydroxyl groups) to disrupt the wollastonite-cellulose bonds (Taghiyari and Nouri 2015; Taghiyari and Sarvari Samadi 2016).

8

H. R. Taghiyari et al.

4 Wood Coatings Wood surfaces are constantly exposed to deposition of dust, dirt, plant pollen, bacteria, fungal spores, and a host of other contaminants. These deposits mar the surface appearance, but also can support microbial growth that further damages the material. Coatings are often used to protect surfaces from this damage, but even these coatings tend to collect debris over time. These accumulations require costly cleaning and shorten coating service life. The development of coatings with self-­ cleaning and antifouling properties would prolong the useful life of a coating, thereby reducing the need for reapplication and diminishing possible effects on the material beneath. Many plant leaves exhibit self-cleaning and antifouling properties, the most well-known being lotus and ramie leaves. These leaves exhibit a property known as superhydrophobicity, which results in extreme high resistance for water penetration (Wulf et  al. 2002; Ganesh et  al. 2011; Salca et  al. 2021). The development of treatments that mimic this ability would markedly reduce the maintenance costs for a range of wood-based materials in exterior exposures. This is, however, a major challenge since most liquids are either water borne or oil borne. As a result, suitable coatings must be both hydrophobic to repel water and oleophobic to repel oil-borne contaminants. Identifying compounds with these contradictory properties remains a challenge, and no single coating has been able to meet these requirements (Zhu and Zhang 2014). However, given the hydrophilic nature of wood and the detrimental effects associated with swelling and shrinkage as wood wets and dries, hydrophobicity would be a more desirable attribute. Liquid behavior on wood surfaces is normally assessed by measuring the contact angle of a water droplet on the wood surface. Contact angles larger than 90° indicate hydrophobicity, while smaller contact angles represent hydrophilicity (Rios et al. 2013). Contact angles approaching zero (much smaller than 90°) are practically hydrophilic. Coatings with very large contact angles (about 150°) are hydrophobic and are therefore practically self-cleaning to either hydrophilic or hydrophobic contaminants, respectively. A number of researchers have attempted to construct superhydrophobic surfaces. An electroless galvanic reaction was created between a copper substrate and a coating containing nanoparticles to synthesize a superhydrophobic nano-functionalized coating in situ (Chapman and Regan 2011). Other researchers electrostatically deposited a nano-fibrous membrane composed of cellulose acetate to create a unitary structure with superhydrophobic properties (Ogawa et al. 2007). The result was a structure similar to the fibers found in ramie leaves. While our focus is on wood-based materials, self-cleaning properties have been explored on many other materials. For example, an electrostatic technique was used to deposit TiO2 nanoparticles on a glass substrate to create a self-cleaning material (Zhang et al. 2005). The researchers initially deposited a single-layer SiO2 coating on a polyelectrolyte-modified glass by means of electrostatic attraction. TiO2 nanoparticles were then deposited over the first layer (SiO2) of coating. The TiO2 concentration was closely related to the degree of self-cleaning and antireflection.

Emerging Nanomaterials for Forestry and Associated Sectors: An Overview

9

Researchers are still working to create self-cleaning coatings for transparent wood. These methods might also be useful for traditional wood-based materials. Surface coatings are also plagued by fouling due to microbial or algal growth. This can also be problematic for packaging and biomedical implants (Banerjee et al. 2010). Deposition of dirt and microbial propagules mars the surface, but the subsequent microbial growth can also mar the surface appearance, and internal growth can reduce coating adherence and, with some fungi, permanently discolor the substrate. This damage, coupled with UV-associated damage, can rapidly reduce coating performance. One approach to minimize the risk of fouling is to functionalize the surface to make it resistant to adhesion. Poly(ethylene glycol) and oligo(ethylene glycol) are among the many compounds that have been explored for this purpose, although both of these materials alter the “feel” of the wood. Lower toxicity biocides are often also added to coatings to both protect the coating while in storage in the can and to limit microbial penetration once applied. These biocides, however, are rarely effective against the entire range of surface colonizing organisms, and many are especially sensitive to UV damage. Nanomaterials may have a role in this regard. Kumar and Sasikumar (2010) used a polyhedral oligomeric silsesquioxane (POSS-NH2) nano-coating that exhibited enhanced resistance to corrosion and reinforced the coating. Their coating still retained a high impedance value of 109 ohm cm2 after 30 days of immersion, demonstrating that it remained intact and protective. Nano-coatings are also being explored for limiting surface damage associated with ultraviolet light. UV energy released into the wood surface creates free radicals that preferentially attack the lignin, leading to rapid depolymerization of this polymer. While the damage is shallow, the process begins within hours of exposure and sharply reduces the surface appearance of the material, leading to premature replacement of sound wood. Coatings can help reduce this damage, but the protective periods afforded by most transparent or semitransparent coatings are limited to 1 or 2 years. Nano-coatings may play a role in this application. Salla et al. (2012) found that nano-zinc oxide amended maleic anhydride-grafted polypropylene (MAPP)based coatings provided good UV protection to rubberwood (Hevea brasiliensis). Zuccheri et  al. (2013) added titanium dioxide nanoparticles, while Nosáľ and Reinprecht (2017) modified their coatings with zinc oxide nanoparticles. A more recent study suggests that low levels of zinc or titanium nanoparticles alone provided little protection against UV damage of radiata pine (Pinus radiata) in outdoor exposures, while iron-oxide nanoparticles provided some protection. Further studies are underway to assess the value of adding iron and zinc nanoparticles to fully formulated coating systems. While suitable self-cleaning, antifouling, and anti-UV coatings remain elusive, success would markedly extend the useful life of many wood-based products in exterior exposures.

10

H. R. Taghiyari et al.

5 Fire Retardants Fire remains one of the biggest risks for wood and wood-based composites, although it is important to note that this becomes less of a risk in larger timbers because the rate of burning is predictable and can therefore be taken into account in design (White and Dietenberger 1999; Hill 2006). Timber also tends to fail slowly as it burns while other materials such as steel fail catastrophically once they become ductile. While wood is often clad in noncombustible materials such as gypsum board, many users prefer to expose the natural beauty of the material. These applications generally require application of either fire retardant coatings or impregnation with fire retardant chemicals. Fire retardants have long been used to protect timber from fire. Older houses were sometimes coated with local clays or the surface was charred to limit oxygen access to the timber beneath to create a protective layer to limit initial flame spread. The two most common methods for limiting fire spread on exposed timber are application of surface coatings or impregnation with fire retardant chemicals. Fire retardant treatments include combinations of chemicals including monoammonium dihydrogen phosphate, ammonium polyphosphates, ammonium pentaborate, diammonium phosphate, borax, zinc borates, aluminum potassium sulfate, and aluminum hydroxide (White and Dietenberger 1999; Ayrilmis et al. 2007; Mantanis et al. 2018, 2020) as well as a range of less acidic organic systems containing urea. Current fire retardants tend to use combinations of materials that reduce fire spread and control smoke. Older formulations were mostly highly acidic and tended to react with and weaken the wood they were designed to protect. These reactions lead to darkening, strength reduction, increased hygroscopicity, dimensional instability, and fastener corrosion. The high treatment levels associated with these formulations also made them difficult to glue or coat (Winandy et al. 2002; Taghiyari 2012). Nano-metals and nano-minerals have been explored for improving fire performance of wood and wood-based composites to fire (Fig. 3) (White and Dietenberger 1999; Taghiyari 2012; Taghiyari et al. 2021d). Nano-silver significantly improved fire properties in solid wood in laboratory tests (Taghiyari 2012). Nano-wollastonite, nano-clay, and nano-sepiolite also improved fire resistance in solid wood and composite panels (Haghighi Poshtiri et al. 2013; Taghiyari et al. 2013b, 2021b, c, d). One advantage of nano-minerals is their low nontarget toxicity. For example, wollastonite was reported to be safe to humans, though precautionary measures need to be taken to prevent prolonged exposure to wollastonite dust because of its risk of producing negative respiratory effects (Huuskonen et al. 1983a, b). Nano-minerals are also noncorrosive. The addition of either nano-silver or wollastonite can also alter the thermal conductivity coefficients of both solid wood and wood-based composites (Taghiyari et  al. 2014d; Hassani et  al. 2019). This results in more rapid dissipation of heat, thereby delaying the time required for a given portion of the wood to reach the combustion temperature. Nano-minerals can also form an insulating layer on the surface, thereby delaying ignition of the wood beneath (Esmailpour et al. 2018, 2019b,

Emerging Nanomaterials for Forestry and Associated Sectors: An Overview

11

Fig. 3  Schematic diagram of the Fixed Fire Test Apparatus (FFTA; Iranian Patent No. 67232; approved by Iranian Research Organization for Science and Technology under license No. 3407; USPTO Pub. No.: US 2019/0212283 A1; Appl. No. 15/866,752). (Taghiyari 2012; Haghighi Poshtiri et al. 2013; Esmailpour et al. 2018, 2020a, b; Taghiyari et al. 2021d)

2020a, b; Taghiyari et al. 2021b, c, d). While these materials do not prevent fire from damaging wood, the ability to delay the process can have important design implications since building occupants have more time to safely evacuate.

12

H. R. Taghiyari et al.

Fig. 4  Atomic structure of pure (a) and Ni-doped (b) graphene flakes. (Esmailpour et al. 2020b)

Another nanomaterial that has been successfully introduced to improve fire properties in wood is graphene (Esmailpour et al. 2020b). Graphene is a one-atom-thick planar sheet of hexagonally arranged carbon atoms (Fig. 4). These sheets are densely packed in a honeycomb crystal lattice. Graphene has received appreciable attention over the last two decades due to its special structure and exceptional properties (Geim and Novoselov 2007; Katsnelson and Iosifovich 2012). These properties have made graphene ideal to be used in electronics, sensors, energy-saving devices, different composites, emerging modern materials, and many other new applications. Addition of graphene in a water-based acrylic-latex paint significantly improved the times to onset of ignition and glowing in beech wood (Esmailpour et  al. 2020b) (Fig. 5). An alternative to fire retardant impregnation is application of intumescent coatings that expand when exposed to elevated temperatures to create a barrier to oxygen movement further into the wood, thereby removing a critical element for combustion. Nanomaterials and nano-fillers incorporating phosphorous, boron, and

Emerging Nanomaterials for Forestry and Associated Sectors: An Overview

13

Fig. 5  Time to onset of ignition and glowing in four treatments of beech specimens (NW nano-­ wollastonite, NG nano-graphene) (letters on each column represent Duncan groupings at 95% level of confidence) (Esmailpour et al. 2020b)

nitrogen compounds have been found to improve fire performance (Wang et  al. 2009; Aziz et al. 2014). Nano-silicon dioxide (SiO2) in ammonium polyphosphate– pentaerythritol–melamine improved both fire performance and reduced corrosion. Addition of nano-sepiolite to an acrylic-latex paint improved fire performance of both unheated and thermally modified wood in terms of time to ignition and glowing, back darkening, burn through, area burned, and weight loss (Taghiyari et al. 2021d). Though both wollastonite and sepiolite are reported to have good fire retardancy, it seems that neither nano-sepiolite nor nano-wollastonite has been explored for incorporation into intumescent paints and coatings. Another approach to improving wood properties is to choose nanoparticles that alter specific wood attributes or functionalize the wood. Functionalization of wood is challenging because it requires the particles to penetrate into the wood cell wall (Fu

14

H. R. Taghiyari et al.

2018). Failure to accomplish this goal leaves large amounts of wood cell wall polymer in a native state and still capable of interacting with moisture. Inorganic clay nanoplatelets were used to create a nanostructured balsa wood hybrid, but the wood had to first be delignified with peracetic acid to create pathways for particle movement (Fu 2018). Energy dispersive X-ray analysis showed high concentrations of nano-clay inside the cell walls. Thermogravimetric analyses (TGA) showed that modified wood had more residual when heated to 800 °C suggesting that nano-clay in the cell wall improved char formation potentially acting as a thermal insulator. Wollastonite and sepiolite were also reported to act as an insulating layer limiting the penetration of piloted fire to go deeper into the wood (Taghiyari et  al. 2013b, 2021b, c, d).

6 Smart Windows Glass has long been the material of choice for windows because it allows light transmittance and helps maintain more uniform temperature (Deb 2000; Banerjee et al. 2010). Energy exchange through windows makes them very important for energy consumption, and slight improvements in thermal performance have major benefits. A smart window automatically adjusts the transmission of sunlight in response to an external stimulus such as a predetermined maximum sunlight, an electrical current connected to smart window using an electronic circuit, or even by the severity of inside or outside heat. The automatic adjustment necessitates constant monitoring for switching between a blocking state and a transparent state. The most well-known smart windows use photochromic glasses stimulated by light, electrochromic glasses that react with electrical currents monitored by electronic circuits and thermochromic glasses that are stimulated by internal or external temperature conditions. These systems have the potential to create enormous energy savings while making building interiors more comfortable for the inhabitants. For example, DeForest et  al. (2015) found a 40% energy savings using smart windows. These technologies also support the move to using natural light in place of artificial electric light to create more biophilic living and working environments (Shehabi et al. 2013; Runnerstrom et al. 2014; Wang et al. 2016a). Nanomaterials have the potential to enhance smart window efficiency by providing faster modulation and coordination with the outside vs. inside light adjustment (Wang et al. 2016a). Nanomaterials can also contribute to significantly longer window service life and, in a different application, endow them with self-cleaning and antifouling properties. Nanomaterials could also be used to selectively block or delete specific light fractions, for example, the infrared and ultraviolet regions without interfering with the visible light spectrum. These attributes would reduce energy consumption and allow more use of natural light (Wang et al. 2016a).

Emerging Nanomaterials for Forestry and Associated Sectors: An Overview

15

7 Transparent Wood Wood is optically opaque, primarily because of the lignin and the existence of numerous voids (as cell lumens) that create a discontinuous pathway for light intrusion. As a result, light normally penetrates only a cell or two inward from the surface (Taghiyari 2013; Taghiyari and Moradi Malek 2014). Light could move more readily through wood if lignin was removed, and the voids were filled with a polymer with the same refractive index as wood. The concept of transparent wood (TW) was first presented by Fink (1992), and the issue has received some further study (Li et al. 2016; Fu 2018; Höglund et al. 2021). Some studies have shown that more than 90% of light can pass through transparent wood (Zhu et al. 2016). Transparent wood can be fabricated by first forming a delignified wood template to act as a scaffold. This essentially removed the chromophores and creates a structure with enhanced permeability. This material is impregnated with a methyl methacrylate monomer that is then polymerized in situ. Although production of clear transparent wood is the primary goal of most studies, hazed transparent wood can filter natural light to provide a sense of privacy and reduce the need for supplemental lighting. Transparent wood also retains some of the properties of the original material, including a lower thermal conductivity coefficient. Therefore, TW can also be beneficial for the conditioning of the interior environment (Vay et al. 2015). TW is claimed to be stronger than glass, making it safer and can be produced from a renewable material. TW samples have only been produced in small dimensions (small blocks) but have tremendous potential for reducing energy consumption in buildings.

8 Nanomaterials: Risk Assessment Nanomaterials have the potential to positively improve functionality of many materials. However, they are not without risk (Seaton et al. 2010). The small scale of these materials allows them to pass more readily into plants and animal than conventional particles of the same composition. Ecotoxicological studies have revealed that nano-metals can accumulate in soils and sediments to reach potentially harmful levels for both humans and wildlife (Seaton et al. 2010; Schrand et al. 2010; Auffan et al. 2014; Ng et al. 2017). Nanoparticles can be inhaled or ingested by humans during manufacturing or use. For instance, nano-copper compounds can be toxic to nontarget organisms and can penetrate cell membranes in living cells (Navya and Daima 2016). These particles can then be transported throughout the body. While actual exposure to nanoparticles remains low, it will be important to continue to examine toxicity issues as these materials become more widely used.

16

H. R. Taghiyari et al.

9 Conclusion Nanomaterials have tremendous potential in a number of areas related to wood processing including enhanced processing efficiency of composite panel production, increased water repellency, improved resistance to physical and biological degradation, and reduced susceptibility to fire. All of these improvements will further enhance the value of wood-based materials as carbon neutral renewable materials.

References Aitken E (2010) Analyses of the effect of silicon on Fusarium wilt on banana. Horticulture Australia, Sydney, NSW Akhtari M, Ganjipour M (2013) Effect of nano-silver and nano-copper and nano- zinc oxide on Paulownia wood exposed to white-rot fungus – IRG/WP 13-30635. In: 44th Annual Meeting of The International Research Group on Wood Protection. Çesme, Turkey, pp 1–8 Akhtari M, Nicholas D (2013) Evaluation of particulate zinc and copper as wood preservatives for termite control. Eur J Wood Wood Prod 71(3):395–396. https://doi.org/10.1007/ s00107-­013-­0690-­7 Akhtari M, Ghorbani-Kokandeh M, Taghiyari HR (2012) Mechanical properties of Paulownia fortunei wood impregnated with silver, copper and zinc oxide nanoparticles. J Trop For Sci 24(4):507–511 Antov P, Savov V, Neykov N (2020a) Sustainable bio-based adhesives for eco-friendly wood composites—a review. Wood Res 65:51–62 Antov P, Mantanis GI, Savov V (2020b) Development of wood composites from recycled fibres bonded with magnesium lignosulfonate. Forests 11:613 Antov P, Jivkov V, Savov V, Simeonova R, Yavorov N (2020c) Structural application of eco-­ friendly composites from recycled wood fibres bonded with magnesium lignosulfonate. Appl Sci 10:7526 Antov P, Savov V, Mantanis GI, Neykov N (2020d) Medium-density fibreboards bonded with phenol-­formaldehyde resin and calcium lignosulfonate as an eco-friendly additive. Wood Mater Sci Eng 16:1751279. https://doi.org/10.1080/17480272.2020.1751279 Antov P, Savov V, Krišťák Ľ, Réh R, Mantanis GI (2021a) Eco-friendly, high-density fiberboards bonded with urea-formaldehyde and ammonium lignosulfonate. Polymers 13:220. https://doi. org/10.3390/polym13020220 Antov P, Krišťák Ľ, Réh R, Savov V, Papadopoulos AN (2021b) Eco-friendly fiberboard panels from recycled fibres bonded with calcium lignosulfonate. Polymers 13(4):639. https://doi. org/10.3390/polym13040639 Antov P, Savov V, Trichkov N, Krišt’ák Ľ, Réh R, Papadopoulos AN, Taghiyari HR, Pizzi A, Kunecová D, Pachikova M (2021c) Properties of high-density fiberboard bonded with urea–formaldehyde resin and ammonium lignosulfonate as a bio-based additive. Polymers 13(16):2775. https://doi.org/10.3390/polym13162775 Aristri MA, Lubis MAR, Yadav SM, Antov P, Papadopoulos AN, Pizzi A, Fatriasari W, Ismayati M, Iswanto AH (2021) Recent developments in lignin and tannin-based non-isocyanate polyurethane resins for wood adhesives—a review. Appl Sci 11:4242. https://doi.org/10.3390/ app11094242 Auffan M, Masion A, Labille J, Diot MA, Liu W, Olivi L, Proux O, Ziarelli F, Chaurand P, Geantet C, Bottero JY, Rose J (2014) Long-term aging of a CeO2 based nanocomposite used for wood protection. Environ Pollut 188(2014):1–7. https://doi.org/10.1016/j.envpol.2014.01.016

Emerging Nanomaterials for Forestry and Associated Sectors: An Overview

17

Ayrilmis N, Candan Z, White R (2007) Physical, mechanical, and fire properties of oriented strandboard with fire retardant treated veneers. Holz Roh Werkst 65:449–458 Aziz H, Ahmad F, Zia-ul-Mustafa M (2014) Nano filler reinforced intumescent fire retardant coating for protection of structural steel. In: Proceedings of the International Civil and Infrastructure Engineering Conference 2014. Springer., InCIEC. ISBN: 978-981-287-289-0, pp 831–844 Bak M, Yimmou BM, Csupor K, Németh R, Csóka L (2012) Enhancing the durability of wood against wood destroying fungi using nano-zinc. In: International Scientific Conference on Sustainable Development & Ecological Footprint. Sopron, Hungary, pp 1–6 Bal BC (2016) Some technological properties of laminated veneer lumber produced with fast-­ growing Poplar and Eucalyptus. Maderas-Cienc Tecnol 18:413–424 Banerjee I, Pangule RC, Kane RS (2010) Design of surfaces that prevent fouling by proteins, bacteria, and marine organisms. Adv Mat 23:690–718 Bari E, Taghiyari HR, Schmidt O, Ghorbani A, Aghababaei H (2015) Effects of nano-clay on biological resistance of wood-plastic composite against five wood-deteriorating fungi. Maderas-­ Cienc Tecnol 17(1):205–212 Bari E, Sistani A, Taghiyari HR, Morrell JJ, Cappellazzi J (2017) Influence of test method on biodegradation of bamboo-plastic composites by fungi. Maderas-Cienc Tecnol 19(4):455–462 Bayani S, Bazyar B, Mirshokraie SA, Taghiyari HR (2019a) Effects of heat treatment on the relative amounts of cellulose in nanosilver-impregnated and untreated poplar wood (Populus alba). Floresta Ambiente 26:e20160398 Bayani S, Taghiyari HR, Papadopoulos AN (2019b) Physical and mechanical properties of thermally-­modified beech wood impregnated with silver nano-suspension and their relationship with the crystallinity of cellulose. Polymers 11:1535. https://doi.org/10.3390/polym11101538 Bayatkashkoli A, Taghiyari HR, Kameshki B, Ravan S, Shamsian M (2016) Effects of zinc and copper salicylate on biological resistance of particleboard against Anacanthotermes vegans termite. Int Biodeter Biodegr 115:26–30 Bekhta P, Noshchenko G, Réh R, Kristak L, Sedliačik J, Antov P, Mirski R, Savov V (2021) Properties of eco-friendly particleboards bonded with lignosulfonate-urea-formaldehyde adhesives and pMDI as a crosslinker. Materials 14:4875. https://doi.org/10.3390/ma14174875 Borrega M, Karenlampi PP (2010) Hygroscopicity of heat-treated Norway spruce (Picea abies) wood. Eur J Wood Wood Prod 68:233–235 Chapman J, Regan F (2011) Nanofunctionalized superhydrophobic antifouling coatings for environmental sensor applications. Advancing deployment with answers from nature. Adv Eng Mater 14:B175–B184 Civardi C, Schlagenhauf L, Kaiser JP, Hirsch C, Mucchino C, Wichser A, Wick P, Schwarze FWMR (2016) Release of copper-amended particles from micronized copper-pressure-treated wood during mechanical abrasion. J Nanobiotechnol 14(77):1–10. https://doi.org/10.1186/ s12951-­016-­0232-­7 Clausen CA (2012) Enhancing durability of wood-based composites with nanotechnology. In: General technical report FPL–GTR–218. Forest Products Laboratory, Department of Agriculture, Madison, WI, pp 1–3 Daly-Hassan H, Kasraoui M, Karra C (2014) Industrial timber production in Tunisia: despite reforestation, dependence on imports is increasing. Bois For Trop 324:29–37 Deb SK (2000) Photovoltaic-integrated electrochromic device for smart-window applications. World Renewable Energy Congress VI, Brighton, UK, July 1–7, 2000 DeForest N, Shehabi A, O'Donnell J, Garcia G, Greenblatt J et  al (2015) United States energy and CO2 savings potential from deployment of near-infrared electrochromic window glazings. Build Environ 89:107–117 Doost-hoseini K, Taghiyari HR, Elyasi A (2014) Correlation between sound absorption coefficients with physical and mechanical properties of insulation boards made from sugar cane bagasse. Compos Part B-Eng 58:10–15 Esmailpour A, Taghiyari HR, Nouri P, Jahangiri A (2018) Fire-retarding properties of nanowollastonite in particleboard. Fire Mater 42:306–315

18

H. R. Taghiyari et al.

Esmailpour A, Taghiyari HR, Golchin M, Avramidis S (2019a) On the fluid permeability of heat treated paulownia wood. Int Wood Prod J 10:55–63 Esmailpour A, Taghiyari HR, Majidi R, Morrell JJ, Mohammad-Panah B (2019b) Nano-­ wollastonite to improve fire retardancy in medium-density fiberboard (MDF) made from wood fibers and camel-thorn. Wood Mater Sci Eng 16:161. https://doi.org/10.1080/1748027 2.2019.1641838 Esmailpour A, Taghiyari HR, Ghorbanali M, Mantanis G (2020a) Improving fire retardancy of medium density fibreboard by nano-wollastonite. Fire Mater 44:759–766 Esmailpour A, Majidi R, Taghiyari HR, Ganjkhani M, Mohseni Armaki SM, Papadopoulos AN (2020b) Improving fire retardancy of beech wood by graphene. Polymers 12:303. https://doi. org/10.3390/polym12020303 Esteves B, Graca J, Pereira H (2008) Extractive composition and summative chemical analysis of thermally treated eucalypt wood. Holzforschung 62:344–351 Figueroa M, Bustos C, Dechent P, Reyes L, Cloutier A, Giuliano M (2012) Analysis of rheological and thermo-hygro-mechanical behaviour of stress-laminated timber bridge deck in variable environmental conditions. Maderas-Cienc Tecnol 14:303–319 Fink S (1992) Transparent wood  – a new approach in the functional study of wood structure. Holzforschung 46:403–408 Freeman MH, Mclntyre CR (2013) Micronized copper wood preservatives: strong indications of the reservoir effect  – IRG/WP 13-30609. In: 44th Annual Meeting of The International Research Group on Wood Preservation. Stockholm, Sweden, pp 1–16 Fu Q (2018) Wood nanotechnologies for transparency, fire retardancy and liquid separation. Doctoral Thesis supervised by Prof. Lars A. Berglund, Dept. of Fiber and Polymer Technology, KTH Royal Institute of Technology, Stockholm, Sweden Ganesh VA, Raut HK, Nair AS, Ramakrishna S (2011) A review on self-cleaning coatings. J Mater Chem 21:16304–16322 Geetha Devi P, SakthiVelu A (2016) Structural, optical and photoluminescence properties of copper and iron doped nanoparticles prepared by co-precipitation method. J Mater Sci Mater Electron 27(10):10833–10840. https://doi.org/10.1007/s10854-­016-­5190-­1 Geim AK, Novoselov KS (2007) The rise of grapheme. Nat Mater 6:183–191 Haghighi Poshtiri A, Taghiyari HR, Karimi AN (2013) The optimum level of nano-wollastonite consumption as fire-retardant in poplar wood (Populus nigra). Int J Nano Dim 4:141–151 Harandi D, Ahmadi H, MohammadiAchachluei M (2016) Comparison of TiO2 and ZnO nanoparticles for the improvement of consolidated wood with polyvinyl butyral against white rot. Int Biodeter Biodegr 108:142–148. https://doi.org/10.1016/j.ibiod.2015.12.017 Hassani V, Taghiyari HR, Schmidt O, Maleki S, Papadopoulos AN (2019) Mechanical and physical properties of oriented strand lumber (OSL): the effect of fortification level of nanowollastonite on UF resin. Polymers 11:1884. https://doi.org/10.3390/polym11111884 Hill C (2006) Wood modification chemical, thermal and other processes. Wiley., ISBN: 0-470-02172-1, p 239 Hong X, Wen J, Xiong X, Hu Y (2016) Shape effect on the antibacterial activity of silver nanoparticles synthesized via a microwave-assisted method. Environ Sci Pollut Res 23(5):4489–4497. https://doi.org/10.1007/s11356-­015-­5668-­z Höglund M, Garemark J, Nero M, Willhammar T, Popov S, Berglund LA (2021) Facile processing of transparent wood nanocomposites with structural color from plasmonic nanoparticles. Chem Mater 33:3736–3745 Hubbe MA, Rojas OJ, Lucia LA (2015) Green modification of surface characteristics of cellulosic materials at the molecular or nano scale: a review. Bioresources 10(3):6095–6206. https://doi. org/10.15376/biores.10.3.hubbe Huuskonen MS, Jarvisalo J, Koskinen H, Nickels J, Rasanen J, Asp S (1983a) Preliminary results from a cohort of workers exposed to wollastonite in a Finnish limestone quarry. Scand J Work Env Hea 9:169–175 Huuskonen MS, Tossavainen A, Koskinen H, Zitting A, Korhonen O, Nickels J, Korhonen K, Vaaranen V (1983b) Wollastonite exposure and lung fibrosis. Env Res 30:291–304

Emerging Nanomaterials for Forestry and Associated Sectors: An Overview

19

Jeevanandam J, Chan YS, Danquah MK (2016) Biosynthesis of metal and metal oxide nanoparticles. ChemBioEng Rev 3(2):55–67. https://doi.org/10.1002/cben.201500018 Jin L, Walcheski P, Preston A (2008) Laboratory studies on copper availability in wood treated with soluble amine copper and micronized copper systems  – IRG/WP 08-30489. In: 39th Annual Meeting of The International Research Group on Wood Protection. Guanacaste, Costa Rica, pp 1–10 Karimi A, Taghiyari HR, Fattahi A, Karimi S, Ebrahimi G, Tarmian A (2013) Effects of wollastonite nanofibers on biological durability of poplar wood (Populus nigra) against Trametes versicolor. Bioresources 8:4134–4141 Kartal SN, Terzi E, Woodward B, Clausen CA, Lebow ST (2014) Chemical remediation of wood treated with micronised, nano or soluble copper preservatives. Holzforschung 68(7):831–837. https://doi.org/10.1515/hf-­2013-­0212 Katsnelson M, Iosifovich M (2012) Graphene: carbon in two dimensions, 1st edn. Cambridge University Press, Cambridge, NY Khoee S, Hashemi A, Molavipordanjani S (2018) Synthesis and characterization of IUdR loaded PEG/PCL/PEG polymersome in mixed DCM/DMF solvent: experimental and molecular dynamics insights into the role of solvent composition and star architecture in drug dispersion and diffusion. Eur J Pharm Sci 114:1–12. https://doi.org/10.1016/j.ejps.2017.11.019 Kumar SA, Sasikumar A (2010) Studies on novel silicone/phosphorus/sulphur containing nano-­ hybrid epoxy anticorrosive and antifouling coatings. Pro Org Coat 68:189–200 Lee JS, Feijen J (2012) Polymersomes for drug delivery: design, formation and characterization. J Control Release 161(2):473–483. https://doi.org/10.1016/j.jconrel.2011.10.005 Lekha MA, Motaung TE, Adnrew JE, Sitohle BB, Gibril M (2016) Effect of mechanical treatment on properties of cellulose nanofibrils produced from bleached hardwood and softwood pulps. Maderas-Cienc Tecnol 18:457–466 Li D (2012) Nanostructuring materials towards conventionally unachievable combination of desired properties. J Nanomater Mol Nanotechnol 1(1). https://doi.org/10.4172/12324-­877 7.1000e102 Li Y, Fu Q, Yu S, Yan M, Berglund L (2016) Optically transparent wood from a nanoporous cellulosic template: combining functional and structural performance. Biomacromolecules 17:1358–1364 Li Y, Fu Q, Rojas R, Yan M, Lawoko M, Berglund LA (2017) Lignin-retaining transparent wood. ChemSusChem 10(17):3445–3451 Lykidis C, Mantanis G, Adamopoulos S, Kalafata K, Arabatzis I (2013) Effects of nano-sized zinc oxide and zinc borate impregnation on brown-rot resistance of black pine (Pinus nigra L.) wood. Wood Mater Sci Eng 8:242–244 Lykidis C, Bak M, Mantanis G, Németh R (2016) Biological resistance of pine wood treated with nano-sized zinc oxide and zinc borate against brown-rot fungi. Eur J Wood Wood Prod 74:909–911 Lykidis C, de Troya T, Conde M, Galvan J, Mantanis G (2018) Termite resistance of beech wood treated with zinc oxide and zinc borate nanocompounds. Wood Mater Sci Eng 13:45–49 Jiang W, Lyu G, Wu S, Lucia LA, Yang G, Liu Y (2016) Supercritical water-induced lignin decomposition reactions: a structural and quantitative study. Bioresources 11:5660–5675 Majidi R, Taghiyari HR, Abdolmaleki D (2019) Molecular dynamics simulation evaluating the hydrophilicity of nanowollastonite on cellulose. J Struct Chem 6:1562–1569 Malviya KD, Chattopadhyay K (2015) High quality oxide-free metallic nanoparticles: a strategy for synthesis through laser ablation in aqueous medium. J Mater Sci 50(2):980–989. https://doi. org/10.1007/s10853-­014-­8658-­5 Mantanis G, Terzi E, Kartal SN, Papadopoulos A (2014) Evaluation of mold, decay and termite resistance of pine wood treated with zinc- and copper- based nanocompounds. Int Biodet Biodeg 90:140–144 Mantanis G, Athanassiadou E, Barbu M, Wijnendaele K (2018) Adhesive systems used in the European particleboard, MDF and OSB industries. Wood Mater Sci Eng 13:104–116

20

H. R. Taghiyari et al.

Mantanis G, Martinka J, Lykidis C, Ševčík L (2020) Technological properties and fire performance of medium density fibreboard (MDF) treated with selected polyphosphate-based fire retardants. Wood Mater Sci Eng 15(5):303–311 Martínez Rivas CJ, Tarhini M, Badri W, Miladi K, Greige-Gerges H, Nazari QA, Galindo Rodríguez SA, Román RÁ, Fessi H, Elaissari A (2017) Nanoprecipitation process: from encapsulation to drug delivery. Int J Pharm 532(1):66–81. https://doi.org/10.1016/j.ijpharm.2017.08.064 Mattos BD, Tardy BL, Magalhães WLE, Rojas O (2017) Controlled release for crop and wood protection: recent progress toward sustainable and safe nanostructured biocidal systems. J Control Release 262:139–150 Milton FT (1995) The preservation of wood, A self study manual for wood treaters. Minnesota Extension Service, University of Minnesota, College of Natural Resources, BU-6413-S, Revised 1995, p. 103 Mora-Huertas CE, Fessi H, Elaissari A (2010) Polymer-based nanocapsules for drug delivery. Int J Pharm 385(1–2):113–142. https://doi.org/10.1016/j.ijpharm.2009.10.018 Nair S, Pandey KK, Giridhar BN, Vijayalakshmi G (2017) Decay resistance of rubberwood (Hevea brasiliensis) impregnated with ZnO and CuO nanoparticles dispersed in propylene glycol. Int Biodeter Biodegr 122:100–106. https://doi.org/10.1016/j.ibiod.2017.05.008 Nosáľ E, Reinprecht L (2017) Anti-bacterial and anti-mold efficiency of ZnO nanoparticles present in melamine-laminated surfaces of particleboards. Bioresources 12(4):7255–7267. https:// doi.org/10.15376/biores.12.4.7255-­7267 Navya PN, Daima HK (2016) Rational engineering of physicochemical properties of nanomaterials for biomedical applications with nanotoxicological perspectives. Nano Convergen 3(1):1–14. https://doi.org/10.1186/s40580-­016-­0064-­z Ng CT, Yong LQ, Hande MP, Ong CN, Yu LE, Bay BH, Baeg GH (2017) Zinc oxide nanoparticles exhibit cytotoxicity and genotoxicity through oxidative stress responses in human lung fibroblasts and Drosophila melanogaster. Int J Nanomed 12:1621–1637. https://doi.org/10.2147/ IJN.S124403 Ninikas K, Mitani A, Koutsianitis D, Ntalos G, Taghiyari HR, Papadopoulos N, A.N. (2021) Thermal and mechanical properties of green insulation composites made from Cannabis and bark residues. J Compos Sci 5(5):132. https://doi.org/10.3390/jcs5050132 Ogawa T, Ding B, Sone Y, Shiratori S (2007) Super-hydrophobic surfaces of layer-by-layer structures film-coated electrospun nanofibrous membranes. Nanotechnology 18:165607. http://iopscience.iop.org/0957-­4484/18/16/165607 Palanti S, Feci E, Predieri G, Francesca V (2012) Copper complexes grafted to amino-­ functionalized silica gel as wood preservatives against fungal decay: mini-blocks and standard test. Bioresources 7:5611–5621 Poletti Papi MA, Caetano FR, Bergamini MF, Marcolino-Junior LH (2017) Facile synthesis of a silver nanoparticles/polypyrrole nanocomposite for non-enzymatic glucose determination. Mater Sci Eng C 75:88–94. https://doi.org/10.1016/j.msec.2017.02.026 Papadopoulos AN, Hill CAS (2002) The biological effectiveness of wood modified with linear chain carboxylic acid anhydrides against Coniophora puteana. Holz als Roh-und Werkstoff 60(5):329–332 Papadopoulos E (2009) Adhesives from renewable resources for binding wood-based panels. J Environ Prot Ecol 10:1128–1136 Papadopoulos AN, Foti D, Kyzas GZ (2020) Sorption behavior of water vapor of wood treated by chitosan polymer. Eur J Wood Wood Produ 78(3):483–491 Papadopoulos AN (2021) Advances in wood composites III. Polymers 13:163 Pizzi A, Papadopoulos A, Policardi F (2020) Wood composites and their polymer binders. Polymers 12:1115 Réh R, Igaz R, Krišt’ák Ľ, Ružiak I, Gajtanska M, Božíková M, Kučerka M (2019) Functionality of beech bark in adhesive mixtures used in plywood and its effect on the stability associated with material systems. Materials 12:1298 Rios PF, Dodiuk H, Kenig S (2013) Self-cleaning coatings. Surf Eng 25:89–92

Emerging Nanomaterials for Forestry and Associated Sectors: An Overview

21

Runnerstrom EL, Llordés A, Lounis SD, Milliron DJ (2014) Nanostructured electrochromic smart windows: traditional materials and NIR-selective plasmonic nanocrystals. Chem Commun 50:10555–10572 Salca EA, Krystofiak T, Lis B, Hiziroglu S (2021) Glossiness evaluation of coated wood surfaces as function of varnish type and exposure to different conditions. Coatings 11:558. https://doi. org/10.3390/coatings11050558 Salla J, Pandey KK, Srinivas K (2012) Improvement of UV resistance of wood surfaces by using ZnO nanoparticles. Polym Degrad Stab 97:592–596. https://doi.org/10.1016/j. polymdegradstab.2012.01.013 Sandak A, Sandak J (2021) Wood modification: characterization, modeling and applications. Coatings 11:869. https://doi.org/10.3390/coatings11070869 Sandberg D (2016) Additives in wood products – today and future development. Wood Sci Eng. https://doi.org/10.1007/978-­981-­10-­0655-­5_4 Sandberg D, Kutnar A, Mantanis G (2017) Wood modification technologies – a review. iForest 10(6):895–908. https://doi.org/10.3832/ifor2380-­010 Savov V, Valchev I, Antov P (2019) Processing factors for production of eco-friendly medium density fibreboards based on lignosulfonate adhesives. In: Proceedings of the 2nd International Congress of Biorefinery of Lignocellulosic Materials (IWBLCM 2019)., ISBN: 978-84-940063-7-1, 4–7 June 2019. Córdoba, Spain, pp 165–169 Savov V, Antov P (2020) Engineering the properties of eco-friendly medium density fiberboard bonded with lignosulfonate adhesive. Wood Industry/Drvna Industrija 71(2):157–162 Schmidt O (2006) Wood and tree fungi: biology, damage, protection, and use. Springer-Verlag, Berlin Heidelberg, p 334 Schmidt O (2007) Indoor wood-decay basidiomycetes: damage, causal fungi, physiology, identification and characterization, prevention and control. Mycol Prog 6:261–279 Schmidt O, Gaiser O, Dujesiefken D (2012) Molecular identification of decay fungi in the wood of urban trees. Eur J For Res 131:885–891 Schrand AM, Rahman MF, Hussain SM, Schlager JJ, Smith DA, Syed AF (2010) Metal-based nanoparticles and their toxicity assessment. Wiley Interdiscip Rev Nanomed Nanobiotechnol 2:544–568. https://doi.org/10.1002/wnan.103 Seaton A, Tran L, Aitken R, Donaldson K (2010) Nanoparticles, human health hazard and regulation. J R Soc Interface 7(Suppl 1):119–129. https://doi.org/10.1098/rsif.2009.0252.focus Shehabi A, DeForest N, McNeil A, Masanet E, Greenblatt J et al (2013) U.S. energy savings potential from dynamic daylighting control glazings. Energ Buildings 66:415–423 Souza RGD, Dan ML, Dias-Guimaraes MA, Guimaraes LAOP, Braga JMA (2018) Fruits of the Brazilian Atlantic Forest: allying biodiversity conservation and food security. An Acad Bras Cienc 90:3583–3595 Spear MJ, Curling SF, Dimitriou A, Ormondroyd GA (2021) Review of functional treatments for modified wood. Coatings 11:327. https://doi.org/10.3390/coatings11030327 Taghiyari HR, Rangavar H, Farajpour Bibalan O (2011) Effect of nano-silver on reduction of hot-pressing time and improvement in physical and mechanical properties of particleboard. Bioresources 6(4):4067–4075 Taghiyari HR, Farajpour Bibalan O (2013) Effect of copper nanoparticles on permeability, physical, and mechanical properties of particleboard. Eur J Wood Wood Prod 71(1):69–77 Taghiyari HR (2012) Fire-retarding properties of nano-silver in solid woods. Springer: Wood Sci Technol 46(5):939–952. https://doi.org/10.1007/s00226-­011-­0455-­6 Taghiyari HR (2013) Effects of heat-treatment on permeability of untreated and nanosilver-­ impregnated native hardwoods. Maderas-Cienc Tecnol 15:183–194 Taghiyari HR, Mobini K, Sarvari Samadi Y, Doosti Z, Karimi F, Asghari M, Jahangiri A, Nouri P (2013a) Effects of nano-wollastonite on thermal conductivity coefficient of medium-density fiberboard. J Mol Nanotechnol 2:1. https://doi.org/10.4172/2324-­8777.1000106 Taghiyari HR, Rangavar H, Nouri P (2013b) Fire-retarding properties of nanowollastonite in MDF. Eur J Wood Wood Prod 71:573–581

22

H. R. Taghiyari et al.

Taghiyari HR (2014) Nanotechnology in wood and wood-composite materials. J Nanomater Mol Nanotechnol 3:1. https://doi.org/10.4172/2324-­8777.1000e106 Taghiyari HR, Moradi Malek B (2014) Effect of heat treatment on longitudinal gas and liquid permeability of circular and square-shaped native hardwood specimens. Heat Mass Transf 50:1125–1136 Taghiyari HR, Schmidt O (2014) Nanotechnology in wood-based composite panels. Intl J Bio-­ Inorg Hybrid Nanomater 3:65–73 Taghiyari HR, Moradi Malek B, Ghorbani Kookandeh M, Farajpour Bibalan O (2014a) Effects of silver and copper nanoparticles in particleboard to control Trametes versicolor fungus. Int Biodeter Biodegr 94:69–72 Taghiyari HR, Bari E, Schmidt O, Tajick Ghanbary MA, Karimi A, Tahir PM (2014b) Effects of nanowollastonite on biological resistance of particleboard made from wood chips and chicken-­ feather against Antrodia vaillantii. Int Biodeter Biodegr 90:93–98 Taghiyari HR, Bari E, Schmidt O (2014c) Effects of nanowollastonite on biological resistance of medium-density fiberboard against Antrodia vaillantii. Eur J Wood Wood Prod 72:399–406 Taghiyari HR, Ghorbanali M, Tahir PMD (2014d) Effects of the improvement in thermal conductivity coefficient by nano-wollastonite on physical and mechanical properties in medium-­ density fiberboard (MDF). Bioresources 9(3):4138–4149 Taghiyari HR, Nouri P (2015) Effects of nano-wollastonite on physical and mechanical properties of medium-density fiberboard. Maderas-Cienc Tecnol 17:833–842 Taghiyari HR, Kalantari A, Ghorbani M, Bavaneghi F, Akhtari M (2015) Effects of fungal exposure on air and liquid permeability of nano-silver- and nano-zinc oxide-impregnated Paulownia Wood. Int Biodeter Biodegr 105:51–57 Taghiyari HR, Sarvari Samadi Y (2016) Effects of wollastonite nanofibers on fluid flow in medium-­ density fiberboard. J For Res 27:209–217 Taghiyari HR, Majidi R, Jahangiri A (2016) Adsorption of nano-wollastonite on cellulose surface: effects on physical and mechanical properties of medium-density fiberboard (MDF). Cerne 22:215–222 Taghiyari HR, Norton J, Tajvidi M (2017) Effects of Nano-materials on different properties of wood-composite materials. In: Bio-based wood adhesives: preparation, characterization, and testing. CRC Press/Taylor & Francis Group, Boca Raton, FL, pp 310–339 Taghiyari HR, Arbabi Ghamsari F, Salimifard E (2018a) Effects of adding nano-wollastonite, date palm prunings and two types of resins on the physical and mechanical properties of medium-­ density fiberboard (MDF) made from wood fibers. Bois For Trop 335:49–57 Taghiyari HR, Majidinajafabad R, Vahidzadeh R (2018b) Wollastonite to hinder growth of Aspergillus niger fungus on cotton textile. An Acad Bras Cienc 90:2797–2804 Taghiyari HR, Avramidis S (2019) Specific gas permeability of normal and nanosilver-­impregnated solid wood species as influenced by heat-treatment. Maderas-Cienc Tecnol 21:89–96 Taghiyari HR, Kalantari A, Kalantari A, Avramidis S (2019) Effect of wollastonite nanofibers and exposure to Aspergillus niger fungus on air flow rate in paper. Measurement 136:307–313 Taghiyari HR, Bari E, Sistani A, Najafian M, Tajick Ghanbary MA, Ohno KM (2020a) Biological resistance of nanoclay-treated plastic composites with different bamboo contents to three types of fungi. J Thermoplast Compos Mater 33(8):1048–1060. https://doi. org/10.1177/0892705718817339 Taghiyari HR, Majidi R, Esmailpour A, Sarvari Samadi Y, Jahangiri A, Papadopoulos AN (2020b) Engineering composites made from wood and chicken feather bonded with UF resin fortified with wollastonite: a novel approach. Polymers 12:857 Taghiyari HR, Hosseini SB, Ghahri S, Ghofrani M, Papadopoulos AN (2020c) Formaldehyde emission in micron-sized wollastonite-treated plywood bonded with soy flour and urea-­ formaldehyde resin. Appl Sci 10:6709. https://doi.org/10.3390/app10196709 Taghiyari HR, Esmailpour A, Majidi R, Morrell JJ, Mallaki M, Militz H, Papadopoulos AN (2020d) Potential use of wollastonite as a filler in UF resin based medium-density fiberboard (MDF). Polymers 12:1435. https://doi.org/10.3390/polym12071435

Emerging Nanomaterials for Forestry and Associated Sectors: An Overview

23

Taghiyari HR, Esmailpour A, Adamopoulos S, Zereshki K, Hosseinpourpia R (2020e) Shear strength of heat-treated solid wood bonded with polyvinyl-acetate reinforced by nanowollastonite. Wood Res 65(2):183–194 Taghiyari HR, Soltani A, Esmailpour A, Hassani V, Gholipour H, Papadopoulos AN (2020f) Improving thermal conductivity coefficient in oreiented strand lumber (OSL) using sepiolite. Nano 10:599. https://doi.org/10.3390/nano10040599 Taghiyari HR, Majidi R, Mohseni Armaki SM, Haghighatparast M (2021a) Graphene as reinforcing filler in polyvinyl acetate resin. Int J Adhes Adhes 113:103075. https://doi.org/10.1016/j. ijadhadh.2021.103075 Taghiyari HR, Militz H, Antov P, Papadopoulos AN (2021b) Effects of wollastonite on fire properties of particleboard made from wood and chicken feather fibers. Coatings 11:518. https://doi. org/10.3390/coatings11050518 Taghiyari HR, Morrell JJ, Papadopoulos AN (2021c) Wollastonite to improve fire properties in medium-density fiberboard made from wood and chicken feather fibers. Appl Sci 11:3070. https://doi.org/10.3390/app11073070 Taghiyari HR, Tajvidi M, Soltani A, Esmailpour A, Khodadoosti G, Jafarzadeh H, Militz H, Papadopoulos AN (2021d) Improving fire retardancy of unheated and heat-treated fir wood by nano-sepiolite. Eur J Wood Wood Prod 79:841. https://doi.org/10.1007/s00107-­021-­01679-­1 Tajvidi M, Gardner DJ, Bousfield DW (2016) Cellulose nanomaterials as binders: laminate and particulate systems. J Renew Mater 4:365. https://doi.org/10.7569/JRM.2016.634103 Taniguchi N, Arakawa C, Kobayashi T (1974) On the basic concept of nanotechnology. Proceedings of the International Conference on Production Engineering, Tokyo, Japan, 26–29 August 1974 Thandavan TMK, Gani SMA, San Wong C, Nor M, R. (2015) Enhanced photoluminescence and raman properties of Al-doped ZnO nanostructures prepared using thermal chemical vapor deposition of methanol assisted with heated brass. PLoS One 10(5):1–18. https://doi.org/10.1371/ journal.pone.0121756 Tjeerdsma BF, Boonstra M, Pizzi A, Tekely P, Militz H (1998) Characterization of thermal modified wood: molecular reasons for wood performance improvement. CPMAS 13 CNMR characterization of thermally modified wood. Holz Roh und Werkstoff 56:149–153 Tjeerdsma BF, Militz H (2005) Chemical changes in hydrothermal treated wood: FTIR analysis of combined hydrothermal and dry heat-treated wood. Holz Roh und Werkstoff 63:102–111 Vay O, De Borst K, Hansmann C, Teischinger A, Muller U (2015) Thermal conductivity of wood at angles to the principal anatomical directions. Wood Sci Technol 49:577–589 Verhaegen D, Randrianjafy H, Rakotondraoelina Andriatsitohaina H, Trendelenburg Rakotonirina MC, Andriamampianina N et al (2014) Eucalyptus robusta for sustainable fuelwood production in Madagascar: review of knowledge and future prospects. Bois For Trop 320:15–30 Wang Z, Enhou H, Liu F, Ke W (2009) Fire and corrosion resistances of intumescent nano-coating containing nano-SiO2 in salt spray condition. J Mat Sci Technol 26:75–81 Wang Y, Runnerstrom EL, Milliron DJ (2016a) Switchable materials for smart windows. Annu Rev Chem Biomol 7:283–304 Wang Z, Yang X, Sun B, Chai Y, Liu J, Cao J (2016b) Effect of vacuum heat treatment on the chemical composition of larch wood. Bioresources 11:5743–5750 White RH, Dietenberger MA (1999) Wood handbook, Chapter 17: Fire safety; Forest Products Laboratory, Gen. Tech. Rep. FPL – GTR – 113, Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, 463 p Winandy JE, Lebow PK, Murphy JF (2002) Predicting current serviceability and residual service life of plywood roof sheathing using kinetics-based models. The 9th Durability of Building Materials and Components Conference, Brisbane, Aeustralia, p. 7 Wulf M, Wehling A, Reis O (2002) Coatings with self-cleaning properties. Macromol Symposia 187:459–468 Xu H, Taghiyari HR, Clauson M, Milota MR, Morrell JJ (2019) Effect of supercritical carbon dioxide treatment on gas permeability of Paulownia fortunei heartwood and sapwood. Wood Fiber Sci 51:1–5

24

H. R. Taghiyari et al.

Xue W, Kennepohl P, Ruddick JNR (2014) Chemistry of copper preservative treated wood  – IRG/WP 14-30651. In: 45th Annual Meeting of The International Research Group on Wood Protection. St. George, UT, pp 1–8 Zhang X-T, Sato O, Taguchi M, Einaga Y, Murakami T, Fujishima A (2005) Self-cleaning particle coating with antireflection properties. Chem Mater 17:696–700 Zhu J, Zhang H (2014) Self-cleaning coatings. Final Report, Department of Chemical and Biochemical Engineering, DRDC-RDDC-2014-C87. The University of Western Ontario, London, ON Zhu M, Song J, Li T, Gong A, Wang Y, Dai J, Yao Y, Wei L, Henderson D, Hu L (2016) Highly anisotropic, highly transparent wood composites. Adv Mater 28:7563. https://doi.org/10.1002/ adma.201600427 Zuccheri T, Colonna M, Stefanini I, Santini C, Gioia DD (2013) Bactericidal activity of aqueous acrylic paint dispersion for wooden substrates based on TiO2 nanoparticles activated by fluorescent light. Materials 6(2013):3270–3283. https://doi.org/10.3390/ma6083270

Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview Petar Antov, Seng Hua Lee, Muhammad Adly Rahandi Lubis, and Sumit Manohar Yadav

Contents 1  Introduction 2  Nanocellulose Application in Bio-Based Wood Adhesives 3  Nanolignin Application in Bio-Based Wood Adhesives 4  Nanoclay Application in Bio-Based Wood Adhesives 5  Challenges and Future Prospects 6  Conclusion References

 26  30  38  45  52  53  53

P. Antov (*) Department of Mechanical Technology of Wood, Faculty of Forest Industry, University of Forestry, Sofia, Bulgaria e-mail: [email protected] S. H. Lee Laboratory of Biopolymer and Derivatives, Institute of Tropical Forestry and Forest Product, Universiti Putra Malaysia, Serdang, Selangor, Malaysia M. A. R. Lubis Research Center for Biomaterials, Indonesian Institute of Sciences, Cibinong, West Java, Indonesia S. M. Yadav Department of Forest Products and Utilization, Forest College and Research Institute, Hyderabad, Telangana, India Centre of Advanced Materials, University of Malaya, Kuala Lumpur, Malaysia © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 H. R. Taghiyari et al. (eds.), Emerging Nanomaterials, https://doi.org/10.1007/978-3-031-17378-3_2

25

26

P. Antov et al.

1 Introduction Nowadays, the design and development of eco-friendly and sustainable materials have become increasingly important for manufacturing various high value-added products with lower environmental footprint for a wide range of industrial applications (Oksman and Bismarck 2014; Kargarzadeh et al. 2018a). The depletion and unsustainable consumption of natural resources, the increased environmental awareness, and the new stricter environmental legislation related to waste management and enhanced valorization of waste and by-products are the main driving forces for modifying the existing industrial models toward low-carbon, circular bioeconomy (Arias et al. 2022; Gillela et al. 2022). In recent years, wood-based panel industry has gone through significant changes due to material and technological advances and has become of the fastest growing manufacturing industries worldwide (Sedliačiková et  al. 2020; Krišťáková et  al. 2021). Due to the increased demands for wood and wood-based materials, which is projected to increase three times between 2010 and 2050 (Dammer et al. 2016), the global production of wood-­ based panels has continuously expanded, reaching an estimated annual production of 367 million m3 in 2020, representing a 107% increase compared with 2000 and about 280% increase compared with 1980 (FAO 2021). The global production of particleboards, fiberboards, and oriented strand board (OSB) panels, commonly used in construction and furniture production, recorded the highest growth with a global production of 250 million m3 in 2020 (FAO 2021). Implementation of circular economy principles in wood-based panel industry, related to the cascading use of wood resources and the growing needs for “green” and sustainable wood-based products, have posed certain challenges to researchers and manufacturers, related to recycling and reusing wood-based panels (Irle et al. 2018; Lubis et al. 2018; Lubke et al. 2020; Bütün Buschalsky and Mai 2021; Hagel et al. 2021), design and development of novel, eco-friendly wood-based panels (Taghiyari et al. 2020a; Ninikas et al. 2021; Antov et al. 2021a, b; Bekhta et al. 2021a, b; Foti et al. 2022), optimization of the available lignocellulosic raw materials (Iždinský et al. 2020; Kminiak et al. 2020; Pędzik et al. 2021, 2022), and search for alternative feedstocks for their production (Taghiyari et  al. 2016, 2018; Esmailpour et  al. 2019; Barbu et  al. 2020a, b; Mirski et al. 2021; Taghiyari et al. 2021; Tudor et al. 2021; Yue et al. 2021; Hejna et al. 2021; Akinyemi et al. 2022). The wood adhesive industry is dominated by synthetic formaldehyde-based resins, such as urea-formaldehyde (UF), phenol-formaldehyde (PF), and melamine-­ urea-­formaldehyde (MUF), commonly produced from petrochemical constituents, i.e., urea, phenol, and melamine (Mantanis et al. 2018; Wibowo et al. 2020; Pizzi et al. 2020; Selakjani et al. 2021; Savov et al. 2021). These conventional thermosetting resins represent about 95% of the total adhesives used for the manufacture of wood-based panels (Mantanis et al. 2018; Kumar and Pizzi 2019). UF resins, produced from the reaction between urea and formaldehyde, are the most predominant type of thermosetting adhesives used for manufacturing wood-based panels with a global annual consumption of about 11 million tons (Kumar and Pizzi 2019). UF

Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview

27

adhesives represent about 80% of the total volume of amino resins produced worldwide, and the remaining 20% are mostly melamine-formaldehyde (MF) resins and some minor amounts of resins produced from other amino compounds or aldehydes (Park and Kim 2008; Kumar and Pizzi 2019). The widespread industrial use of formaldehyde-based wood adhesives is due to their versatile characteristics, such as excellent chemical reactivity, flexibility, water solubility, ease of handling, good thermal stability, low curing temperatures and short pressing times, ease of handling, and cost-effectiveness (Dunky 2003; Frihart 2015; Mantanis et  al. 2018). However, a major disadvantage of these synthetic resins is the formaldehyde emission from the wood-based panels during their manufacturing and use, which is associated with certain environmental problems and serious effects on human health, including respiratory tract and skin irritation, sensitization, genotoxicity, and cancer (U.S.  Consumer 2013; Łebkowska et  al. 2017; Bekhta et  al. 2021a,  b). In this respect, new stricter regulations on the free formaldehyde emission from woodbased panels were adopted in Europe, the United States, and Japan, which have increased the industrial interest in the development of novel ultra-low formaldehyde emitting wood adhesives with enhanced characteristics (Solt et  al. 2019; Kristak et al. 2022). The harmful effect of formaldehyde release from wood composites can be also avoided by using isocyanate adhesives, namely polymeric 4,4′-diphenyl methane diisocyanate (pMDI), which do not contain formaldehyde (Frazier 2003; Pizzi et al. 2020). The main limiting factors for their more comprehensive industrial application as wood adhesives are the relatively higher cost of pMDI than the standard formaldehyde-based wood adhesives. In addition, the low wetting angle of pMDI compared with water-based condensation resins can result in starved glue lines, which need to be adjusted (Hornus et  al. 2020). Another viable options to reduce the free formaldehyde emission from wood-based panels include the addition of various organic, inorganic, and mineral compounds as formaldehyde scavengers in the adhesive systems, e.g., lignin, tannins, rice husk, hemp or wheat flour, bark, pulp and paper sludge, urea, phosphates, nanoparticles, charcoal, pozzolan, wollastonite, and zeolites (Eom et  al. 2006; Kim 2009; Buyuksari et  al. 2010; Darmawan et  al. 2010; Migneault et  al. 2011; Boran et  al. 2012; Costa et  al. 2013a, b, 2014; de Cademartori et al. 2019; Antov et al. 2020a, b; Taghiyari et al. 2020a, b; Camlibel 2020; Barbu et al. 2020a, b; Kawalerczyk et al. 2020a, b; Réh et al. 2021); modification of hot pressing parameters, i.e., pressing temperature and pressing time (Puttasukkha et  al. 2015; Bekhta et  al. 2020); surface treatment or post-treatment of the finished composites (Roffael 2011; Hematabadi et al. 2012; Bekhta et al. 2018); and using environmentally sustainable, formaldehyde-free, biobased wood adhesives (Nordström et al. 2017; Hemmilä et al. 2017; Tisserat et al. 2019; Hosseinpourpia et al. 2019; Ghani et al. 2019; Sarika et al. 2020; Arias et al. 2021a; Saud et  al. 2021). Addition of different metal and mineral nanomaterials (like nanosilver, nanosepiolite, and nanowollastonite) to formaldehyde-based resins was reported not only to improve physical and mechanical properties in wood-based composite panels (Taghiyari et al. 2011; Rangavar et al. 2013) but also to decrease hot-pressing time by means of improving thermal conductivity in panels and even to improve shear strength in polyvinyl acetate resin by graphene as well (Taghiyari

28

P. Antov et al.

Fig. 1  Natural raw materials for the production of eco-friendly bio-based wood adhesives (Arias et al. 2021b). (Copyright from Elsevier with License number 5265341465060)

et al. 2011, 2020c, 2022). Resin-free wood-based composite panel is another topic for researchers to work on, though no promising results have yet been achieved (Taghiyari et al. 2020d). Numerous studies were focused on the development of novel, “green” bio-­ adhesives for manufacturing wood-based panels, derived from renewable feedstocks and efficient valorization of waste and by-products, such as technical lignins (lignosulfonates, hydrolysis, kraft, and organosolv lignin) (El Mansouri et al. 2006; Antov et al. 2020a, b, 2021a, b; Chen et al. 2020; Saražin et al. 2021; Borrero-López et al. 2021; Singh et al. 2022); modified, condensed, and hydrolyzed tannins (Tomak and Gonultas 2018; Ndiwe et al. 2019; Dunky 2020; Wedaïna et al. 2021; Oktay et al. 2021; Aristri et al. 2021a; Chen et al. 2022); soy (soybean, soybean protein, and soybean meal) (Frihart and Satori 2013; Chen et  al. 2017; Ghahri and Pizzi 2018; Zhang et al. 2020); starch (Gu et al. 2019; Sun et al. 2018; Luo et al. 2020; Arias et al. 2021a); combination of different natural raw materials, e.g., corn flour and lignin (Younesi-Kordkheili and Pizzi 2022); corn starch and mimosa tannin (Oktay et al. 2021); soybean protein concentrate modified with condensed mimosa tannin (Esposito et  al. 2022); soy protein and commercial flavonoid (quebracho) tannin (Ghahri et al. 2022); and addition of modified corn straw lignin into freezing activated wood fibers for manufacturing binderless fiberboard panels (Zhang et al. 2022). A graphical representation of the main groups of natural raw materials used in the development of bio-based wood adhesives is shown in Fig. 1. The potential of other bio-sourced natural materials for the preparation of bio-­ based wood adhesives has also been evaluated. A number of studies have reported promising results on the application of carbohydrates, i.e., polysaccharides, oligomers, gums, and monomeric sugars, in adhesive applications. Chitosans, the second most abundant biodegradable polysaccharides after cellulose, derived from crustacean shells, represent a viable and sustainable alternative, as they have numerous amine and hydroxyl reactive groups (Umemura et al. 2003; Abdelmoula et al. 2021; Khalaf et al. 2021; Ilyas et al. 2022). Furanic-aldehyde resin, prepared from furfuryl

Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview

29

alcohol reacted with nontoxic, nonvolatile aldehyde (glyoxal), demonstrated good water resistance and bonding strength when used for plywood manufacturing (Xi et al. 2020). The use of wood or other lignocellulosic materials liquefied with ethylene glycol, sulfuric acid, or phenol is another approach that showed promising wood adhesive characteristics (Lee and Liu 2002; Gagnon et  al. 2004; Kunaver et al. 2010). Many studies reported the use of citric acid as a cross-linking agent or a hardener, applied for enhancing the adhesive performance (Santos et  al. 2021; Segovia et al. 2021), as well as main eco-friendly bonding agent (Lee et al. 2020; Sutiawan et al. 2021; Santos et al. 2022). Recent research works demonstrated the potential of soy protein isolate, lignin, and tannin as renewable natural materials for the synthesis of environmentally friendly, non-isocyanate polyurethanes (NIPUs) used for bonding wood (Aristri et al. 2021a; Chen et al. 2021; Sarazin et al. 2021). The application of unsaturated vegetable oils, e.g., seed oil derivatives for wood adhesives, was also investigated (Tasooji et al. 2010; Sahoo et al. 2017). Successful attempts of using cashew nut shell liquid, composed mainly of cardanol, for the development of wood adhesives was also reported (Pizzi 2016; Jial et al. 2019; Saud et al. 2021). Markedly, most of the research works on the formulation of fully bio-based, formaldehyde-free wood adhesives have been developed at a laboratory scale and focused mostly on the chemical characterization and modification of bio-sourced raw materials used and investigation of the physical and mechanical characteristics of the laboratory-fabricated wood composites. The main challenges for the development of 100% bio-based wood adhesives are the needs for additional modification of natural feedstocks to improve their chemical reactivity, the decreased dimensional stability and mechanical properties of the wood-based panels produced, and the need to modify the technological parameters, e.g., extension of pressing time (Savov et  al. 2019). In terms of commercial utilization, only tannin-based bio-­ adhesives have found wider industrial application (Pichelin et al. 2006; Valenzuela et al. 2012; Zhou and Du 2019). With the increasing ecological concerns due to the extensive use of petroleum-­ derived materials, the development of innovative high-value wood adhesives for novel applications, combining enhanced properties, cost-effectiveness, and lower environmental impact is of great importance (Trache et al. 2020). Nanomaterials are widely employed in different industrial sectors to improve change mechanical, chemical, thermal, and properties of various materials (Kaboorani et  al. 2012; Vineeth et al. 2019a). In composite science, the addition of nanomaterials is reported to increase flexural strength, durability, and elasticity of materials (Miyashiro et al. 2020; Köse et  al. 2020). Bio-based nanomaterials, derived from abundant and renewable lignocellulosic natural resources, represent a feasible and “green” option due to their intrinsic characteristics, such as annual renewability, biodegradability, low density, high mechanical and thermal properties, dimensional stability, and excellent reinforcing capacity (Taghiyari et al. 2020a). The addition of nanomaterials in wood adhesives could significantly reduce the unsustainable consumption of fossil-derived chemicals. Nanomaterials are a sustainable and cost-effective alternative to the conventional synthetic formaldehyde-based wood adhesives, acting as

30

P. Antov et al.

both binders and structural reinforcements in adhesive systems used for manufacturing wood composites (Vineeth et  al. 2019b). Markedly, the incorporation of nanomaterials is reported to decrease the harmful free formaldehyde emission from finished wood-based panels and enhance their mechanical properties (Tajvidi et al. 2016; Jiang et al. 2018; Tayeb et al. 2018; Lengowski et al. 2019; Karthäuser et al. 2021). Therefore, the aim of this chapter was to present and evaluate the potential applications of nanomaterials, i.e., nanocellulose, nanolignin, and nanoclay as binders and reinforcing agents in various bio-based wood adhesives, and evaluate their effects on adhesive performance. These nanomaterials have been selected on the basis of the existing literature data reporting improved functional characteristics of bioadhesives and wood-based panels (Bandara et al. 2017; Phanthong et al. 2018; Papadopoulos et al. 2019).

2 Nanocellulose Application in Bio-Based Wood Adhesives Cellulose is the most abundant renewable biomaterial and its natural affinity for self-adhesion makes it a potential material in adhesion science. Cellulose materials can be found in a variety of forms, but the most common are microfibrillated cellulose (MFC), cellulose nanocrystals (CNCs), and bacterial nanocellulose (BNC) (Hakimi et al. 2021). Nanocellulose can be divided into two types: (1) short and needle-shaped nanocrystalline cellulose or cellulose nanocrystals (CNCs), also known as nanowhiskers (CNWs) or nanocrystalline cellulose (NCC), and (2) nanofibrillated cellulose or slender cellulose nanofibers (CNFs) (Mohammadinejad et al. 2016, Kargarzadeh et  al. 2018b). Aside from these two subcategories, another important subcategory of nanocellulose is bacterial nanocellulose (BNC) (Mondal 2017). BNC has a very similar structure to plant cellulose, but it is much purer. Furthermore, when compared with plant cellulose, BNC has superior water retention capabilities (Brigham 2018). The key properties of cellulose and the characteristics of the nanoscale interact synergistically in nanocellulose. Because of their high surface-area-to-volume ratio, cellulose nanomaterials are adaptable to a wide range of applications. Because of their high mechanical properties and aspect ratio, cellulose nanomaterials can be used as polymer reinforcement (Moon et al. 2016). The availability of large quantities of cellulose nanomaterials in recent years has increased the possibility of these materials to be used in a variety of applications. Cellulose nanomaterials can be used as an additive in adhesives, paper-based products, drilling fluids, cement-based materials, food coatings, transparent-flexible electronics, catalysis support structure, and biomedical applications (Moon et al. 2016). In wood adhesive applications, fillers such as wood or wheat flour have been used to improve the performance of plywood adhesive systems (So and Rudin 1990; Réh et al. 2021). However, owing to the higher strength-to-weight ratio, micro- or nanoscaled cellulose could lead to better reinforcement efficiency and confer better properties to the adhesive system (Seydibeyoglu and Oksman 2008). Microfibrillated

Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview

31

Fig. 2  Incident light microscopic image of a typical wood adhesive bond line using the industrial wood adhesive urea-formaldehyde compared with a typical bond line using fibrillated material (inset) (Pinkl et al. 2017). (Open access)

cellulose, on the other hand, falls short when it comes to penetrating the wood structure. Pinkl et al. (2017) found that microfibrillated cellulose suspensions could only match the binding strength of commercial urea-formaldehyde adhesive by 60%. When utilizing microfibrillated cellulose instead of conventional wood glue, no penetration into porous wood structure was detected. The adhesive bond lines may be seen in Fig. 2 as a very sharp interface between compressed fibrillated material between the glued wood pieces. Lack of penetration of microfibrillated cellulose is therefore a shortcoming compared with that of conventional wood adhesive. A number of researchers have used nanocellulose as a reinforcing agent in formaldehyde-­based resins during the production of a wide range of wood-based panels, including particleboard, plywood, OSB, medium density fiberboard, laminated veneer lumber, and so on. Because urea-formaldehyde (UF) resin is well-­ known for its strong adhesion characteristics to the majority of cellulose-containing materials, nanocellulose is a suitable and promising reinforcing agent (Kaur et al. 2002; Singha and Thakur 2008). Furthermore, Veigel et al. (2012) stated that during particleboard production, the UF resin is atomized into fine droplets 40–60 μm in diameter before binding wood particles. As a result, using reinforcing agents at micro- or nanoscales is critical for achieving desired results. When nanocellulose

32

P. Antov et al.

Table 1  Applications of nanocellulose in bio-based adhesives Adhesive Zein- and gluten-­ protein based Cottonseed protein-based Soy protein-based

Soybean meal-based

Nanocellulose Cellulose nanofibers (CNF)

Wood products Birch plywood

Cellulose nanocrystals (CNC) and cellulose nanofibers (CNF) Cellulose nanofibrils (CNF)

Maple wood strips

Potato starch

Cellulose nanowhiskers (CNW) Biomineralized cellulose nanofibrils Nanocrystalline cellulose (NCC) Cellulose nanofibers (CNF)

Tannin

Cellulose nanofibers (CNF)

Lignin-based phenol-formaldehyde (LPF)

Nanocrystalline cellulose (NCC)

Soybean meal-based Soybean meal-based

White maple and southern yellow pine wooden block Pine plywood Plywood Poplar plywood Spruce lap joint Beech and Norway spruce particleboard Yellow birch plywood

References Oh et al. (2019) Cheng et al. (2019) Podlena et al. (2021) Gao et al. (2012) Li et al. (2021) Li et al. (2017) Jiang et al. (2018) Cui et al. (2015) Liu et al. (2015)

was mixed with formaldehyde-based resin, several benefits were reported: improved dimensional stability (Veigel et al. 2012), improved internal bond for particleboard (Yildirim and Candan 2021), improved shear strength for plywood (Lengowski et al. 2021), and lower formaldehyde emission (Ayrilmis et al. 2016; Kawalerczyk et al. 2020a, b). Bio-based wood adhesives have gained significant attention in recent years as a replacement for synthetic adhesives in the wood-based panel industry. Nonetheless, bio-based adhesives such as protein, starch, lignin, and tannin frequently require modification or reinforcement to achieve properties comparable with synthetic resins. Nanocellulose reinforcement was deemed a promising method due to its environmentally friendly nature, as it is abundantly available from renewable lignocellulosic biomass. Nanocellulose has a high potential for use as a bio-based cross-linker in the development of high-performance bio-based adhesives due to its abundant surface reactive groups and extraordinary mechanical performance resulting from its internal highly ordered crystalline structure. A summary of the potential applications of nanocellulose in different types of bio-based adhesives, based on previous published research works, is given in Table 1. Protein-rich soybean meal-based adhesive is one type of bio-based adhesive showing great utilization potential in wood-based industry. Nonetheless, panels bonded with soybean meal-based adhesives exhibited a low resistance to water (Li et al. 2017). Therefore, nanocellulose was employed to enhance the properties of these soybean meal-based adhesive. Gao et  al. (2012) discovered that adding

Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview

33

Fig. 3  The cross-section of the cured adhesives of (a) soybean meal adhesive, (b) soybean meal/ CNW adhesive, (c) soybean meal/CNW/NaOH adhesive, (d) soybean meal/CNW/NaOH/PEG adhesive, and (e) soybean meal/NaOH/PEG adhesive (Gao et al. 2012). (Open access)

cellulose nanowhiskers (CNW) to soybean meal-based adhesive increased the water resistance of plywood. Additionally, the addition of CNW produced a smoother adhesive surface with fewer holes and cracks. The tight and cured structure effectively prevents water intrusion, resulting in improved water resistance (Fig. 3).

34

P. Antov et al.

Fig. 3 (continued)

However, because these interactions are based on physical bonding between the adhesive and the nanocellulose, the enhancement is limited. According to Li et al. (2017), if chemical bonds can be formed, the performance of soybean meal-based adhesives can be significantly improved. Li et al. (2017) incorporated ethylene glycol diglycidyl ether (EGDE) and nanocrystalline cellulose (NCC) modified by a silane coupling agent into soybean meal-based adhesives to improve the adhesive’s physicochemical properties. The formation of chemical cross-linking between epoxy groups of EGDE and NCC with protein molecules of soybean meal-based adhesives improved the thermal stability, dry strength, and wet shear strength of the soybean meal-based adhesive. Figure 4 depicts the reaction mechanisms of EGDE, MNCC, and soy protein molecules. The cross-sectional scanning electron microscopy (SEM) photos of the soybean meal-based adhesives produced by Li et al. (2017) are shown in Fig. 5. The cured soybean meal-based adhesives supplemented with EGDE have a homogeneous structure free of holes and cracks, as shown in the figures (Fig.  5a). The cross-­ section of the cured glue became slightly rougher after the addition of NCC (Fig. 5b), showing that the inclusion of NCC reduced the adhesive’s brittleness (Barari and Omrani 2016). The addition of modified NCC resulted in even rougher shattered surfaces (Fig. 5c), as well as a ductile fracture feature in the glue (Zhang and Xia

Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview

35

Fig. 4  Schematic illustration of the reaction mechanism of ethylene glycol diglycidyl ether (EGDE), modified NCC (MNCC), and soy protein molecules (Li et al. 2017). (Open access)

Fig. 5  Cross-sectional scanning electron microscopy photographs of (a) soybean meal-based adhesive with ethylene glycol diglycidyl ether (EGDE), (b) soybean meal-based adhesive with EGDE and NCC, and (c) soybean meal-based adhesive with EGDE and modified NCC (Li et al. 2017). (Open access)

2016). These ductile structures are reported to be able to withstand the spread of layer cracks, resulting in improved water resistance. Li et al. (2021) added biomineralized cellulose nanofibril and a cationic long-­ alkyl-­chain quaternary salt (LAQ) functionalized aminoclay (LAQ@AC) to soybean meal-based adhesive to improve its mechanical and antibacterial properties. As a result, the adhesive’s cohesion and adhesion strength, as well as its dry and wet shear strengths, improved significantly. Aside from that, the addition provides the soybean meal-based adhesive with desirable flame retardancy and antibacterial activity. Another study by Podlena et al. (2021) also reported that the addition of CNF could improve the strength of the soybean protein isolate (SPI)-based adhesive significantly. In fact, the modified SPI-based adhesive performed better compared with that of UF resin. Performance of another type of proteins, namely zein- and

36

P. Antov et al.

Fig. 6  SEM images of the debonded surfaces by the single-lap shear test: (a and a’) neat zein and (b and b’) zein containing 3% CNFs (Oh et al. 2019). (Copyright from Elsevier with License number 5280560395372)

gluten-based, could also be improved by the addition of CNF (Oh et  al. 2019). According to the study, plywood made from zein-based adhesive combined with 2 wt% CNF and 2 wt% glutaraldehyde had a higher bending strength (MOR) and modulus of elasticity (MOE) values than MDI-bonded plywood. Gluten-based adhesive-bonded plywood had higher MOE but slightly lower MOR than MDI-­ bonded plywood at 5 wt% CNF loading. SEM was used to examine the surface morphology of debonded surfaces of neat zein and gluten adhesives. Fibril-like structures were clearly visible being dragged out of the fracture surface of the zein/CNFs adhesive, as shown in Fig.  6. These high-strength cellulose nanofibers serve as nano-reinforcement, spreading the load from the zein matrix and improving the bond’s strength and modulus. The observation backs with the findings that the inclusion of CNFs improved the zein adhesive’s strength. In comparison with CNC, CNF is expected to have a more efficient reinforcement impact due to its higher aspect ratio (Mariano et  al. 2014; Goodsell et  al. 2014). As a result, higher CNC loading levels are frequently required to improve the properties of the bio-based adhesive. Cheng et al. (2019) investigated the effects of CNF and CNC addition on the performance of a cotton seen protein isolate (CPI) wood adhesive. At 2 wt% CNF addition, a 22% increase in adhesive strength was

Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview

37

Fig. 7  SEM micrographs of (a) acrylate epoxidized soybean oil-based polymer, (b) with 10 wt% CNC addition, and (c) with 10 wt% CNF addition (Barkane et al. 2021). (Open access)

reported when compared with the CPI-based adhesive alone. Meanwhile, adding 10 wt% CNC resulted in a 16% increase in adhesive strength. A similar finding was made for a soy protein isolate (SPI) wood adhesive. Adhesive strength increased by 25% and 15% when CNF and CNC were added at 2% and 10%, respectively, compared with control SPI. Barkane et al. (2021) investigated the effectiveness of CNC and CNF in further depth. As shown in Fig. 7, UV-light-curable resin consists of an acrylated epoxidized soybean oil polymer matrix that has a rather smooth surface (Fig. 7a). In the polymer matrix, CNC revealed an unusually homogenous dispersion (Fig. 7b), with very few agglomerates. It suggests that acrylate epoxidized soybean oil interacts and adheres well with CNC. Meanwhile, the polymer matrix containing CNF has a significantly rougher structure. The CNF can generate an entangled nanofiber mesh-­ like structure in the polymer matrix, according to the authors. Galland et al. (2014) made a similar observation as well. In terms of thermal stability, CNF inclusion is preferred over CNC, according to the findings. On the other hand, CNC reinforcement resulted in increased storage and loss modulus and indicated higher stiffness of the nanocomposite. Apart from protein-based resins, nanocellulose has also been incorporated into tannin resin for particleboard fabrication. Cui et al. (2015) reinforced tannin resin with 1, 2, and 3 wt% CNF that served as a binder for the production of beech and

38

P. Antov et al.

Norway spruce particleboards. After the addition of CNF, the viscosity of the tannin resin increased drastically from 350  mPa.s (pure tannin) to 11,270  mPa.s (tannin + 3 wt% CNF), most likely due to strong hydrogen bond network between CNF and interaction with tannin molecule. However, gelation time did not differ significantly. The addition of CNF improved the mechanical properties and short-term thickness swelling of the particleboard significantly. After 2 h of water immersion, particleboard bonded with tannin + 2 wt% CNF had the highest MOE and internal bond (IB) strength, but the lowest thickness swelling (TS). Based on their findings, the authors concluded that 2 wt% CNF was the best loading level for improving tannin adhesive performance. When the CNF loading level was increased above 2%, both mechanical and physical properties of the particleboard were slightly reduced. Bonding strength of starch adhesive was improved by the addition of 0.96% CNF suspensions (Jiang et  al. 2018). Liu et  al. (2015) incorporated NCC into lignin-­ based phenol-formaldehyde (LPF) resin and found that the shear strength of the plywood was improved. The optimum NCC content was ranging between 0.25% and 0.5%. Pure nanocellulose has also been used directly as a particleboard binder. For instance, Amini et al. (2017) used CNF alone as a binder to create particleboard of various densities. The ratios of Southern pine wood particle and CNF in the study are 85:15 and 80:20, respectively. MOR and MOE values of the particleboard increased with increasing density. MOR increased when CNF content was increased from 15% to 20%. However, the changes in MOE were insignificant. The TS and water absorption (WA) of particleboard bonded with 15% and 20% CNF, respectively, did not differ significantly. Hunt et al. (2017) discovered that the CNF ratio had a significant impact on the internal bond of particleboard. The limit appears to be 10% CNF, as any increase in CNF above that ratio resulted in a reduction in internal bond. A higher moisture content of the furnish may be associated with a higher CNF ratio. As a result, steam pressure increased during pressing, resulting in bonding failure. On the other hand, a study by Kojima et al. (2018) reported that particleboard from recycled particles bonded with 20 wt% CNF displayed the best bending and IB strength. The lowest TS and WA values were obtained for the panels bonded with 20 wt% CNF. At this loading level, the particleboard had comparable performance with that of particleboard bonded with 1 wt% synthetic resin.

3 Nanolignin Application in Bio-Based Wood Adhesives Bio-based wood adhesives made from lignin, a renewable natural substance, have been well studied and reported by several researchers (Kalami et al. 2017; Ang et al. 2019; Yang et al. 2019; Luo and Shuai 2020; Aristri et al. 2021a, b). Lignin is the second most abundant biopolymer on earth, after cellulose. Originating from plants, lignin exists in large quantities in plants after cellulose and mainly serves as a mechanical support and binder to the plant fibers. Apart from that, lignin resembles a sealant that reduces permeation of water through cell walls of the xylem (Adler

Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview

39

1977; Boerjan et al. 2003). The discovery of lignin and its subsequent uses in adhesives formulation are entangled in scientific progress in the paper and pulp industry. The enormous global manufacturing of paper and pulp began around 1850 with wood being utilized as a resource (Adler 1977). Over time, this technology was adopted in the western hemisphere via the Middle East, and wood was replaced with other plant materials with advanced cellulosic content such as cotton, flax, and linen. It was then discovered that wood is not uniform in structure, but contains cellulose and a “covering material” termed as lignin (Boerjan et al. 2003). The lignin structure varies considerably among plant species, due to the different proportions of the monomers of lignin, so called monolignols (Boerjan et al. 2003). They are phenylpropane units, which differ only from the degree of substitution by methoxyl groups on the aromatic ring. Softwood lignins are comprised almost solely of coniferyl alcohol, while hardwood lignins of both coniferyl and sinapyl alcohol and grass lignins of all three types of monomer (Beisl and Friedl 2017; Chauhan 2020). The proportions of the three monomer types in lignin dictate the type of inter-unit linkages present in the lignin molecule, which in turn determines the degree of branching, as well as the reactivity of lignin. The lignin structure also differs depending on the biological tissue it originates. Table 2 presents the overview of available lignin in the market from different raw materials (Hussin et al. 2022). Most of lignins are kraft, lignosulfonate, organosolv, soda, and hydrolysis, which isolated from hardwood, softwood, and annual plants. Table 2  Overview of available lignin in the market from different raw materials Raw materials Type of lignin Hardwood Kraft

Softwood

Annual plants

a

Tg (°C)a 145– 150 Lignosulfonate 130– 135 Organosolv 90– 110 Hydrolysis 75– 90 Kraft 140– 150

Solubility Alkali

Trade names Suppliers Indulin AT Ingevity

Water

Borresperse

Organic solvents and alkali

Biolignin, Lignol

Alkali

Biochoice, Amalin, Lineo Reax

Ref. Vahabi et al. (2021), Hussin Borregaard et al. (2022), Adler (1977), Tomani (2010), Gosselink CIMV et al. (2004a, b), Stewart (2008), Sweetwater Toledano et al. (2010) Domtar, West fraser, Stora Enso Borregaard

Lignol

Fraunhofer

Protobind Fabiola

Greenvalue CBP, TNO

Sunburst, Sunliquid

Clariant

Lignosulfonate 135– Water 140 Organosolv 90– Organic 100 solvents and alkali Soda 140 Alkali Organosolv 90– Organic 100 solvents Hydrolysis 80– 90

Tg is measured using differential scanning calorimetry

40

P. Antov et al.

Biorefineries and pulping industries produce lignin as a by-product through various processes such as kraft, organosolv, soda, hydrolysis, and lignosulfonate (Adler 1977; Gosselink et al. 2004a, b; Stewart 2008; Toledano et al. 2010; Tomani 2010; Vahabi et  al. 2021; Hussin et  al. 2022). A target of 79 billion liters of second-­ generation biofuels needs to be produced within the year 2022 (Hussin et al. 2022). As per the assumption, 355 L of bioethanol can be produced from one ton of dry biomass, and total of 223 million tons of dry biomass is processed every year, thus generating 62 million tons of lignin (Chauhan 2020). Most of the lignin produced nowadays is used as boiler fuel whereas only a small portion is used for the production of value-added products. The type of plant material and its processing methods decides the physicochemical properties of lignin. Lignin is inexpensive and possesses number of excellent features, e.g., high thermal stability, antioxidant activity, and high amount of carbon and favorable stiffness. However, different types of lignin show distinct variants in terms of functional groups, elemental composition, and molecular weight. These advantages increased the interest among researcher for the conversion of lignin into value-added products to be used in different applications. The lignin produced from kraft process is shown to possess particles in the size range of 10  μm to >100  μm; however, it harms the mechanical properties of the blends (Hussin et al. 2022). Nanolignin (NL) particles is one of the best strategies to improve the blending properties of lignin since they possess novel characteristics such as high surface area and improved properties compared with original material. Furthermore, they can be easily surface modified due to the availability of huge number of functional groups like thiols, aliphatic hydroxyl, and phenolic, which can be chemical modified, thus enhancing their application potential (Vahabi et  al. 2021). Thus, the researchers recently shifted their interest toward the preparation of NL particles and exploring their potential applications. It is expected that NL particles will play a vital role in promoting lignin valorization, similar to synthetic polymer nanoparticles that contribute in the polymer industry (Ghahri et al. 2021). Recently, various kinds of NL particles are being synthesized from different resources using a combination of chemical and physical methods. Different approaches such as polymerization, acid precipitation, solvent exchange, ultrasonication, self-assembly, interfacial cross-linking and emulsion, antisolvent precipitation, microbial and enzyme mediated, freeze-drying and thermal stabilization, homogenization, and alkaline precipitation have been discovered by which lignin can be converted into NL particles (Frangville et  al. 2012; Chauhan 2020). Acid precipitation method was the established one to produce novel nontoxic and biodegradable NL. The NL were produced using two different methods to compare its stability upon change in pH solution before precipitation as shown in Fig. 8. First, the precipitation of NL is obtained from a solution of Indulin AT (IAT) in ethylene glycol (EG) by slowly adding aqueous hydrochloric acid (HCl) solution (Fig. 8a). The precipitated NL is pH-stable up to pH 10 after dialysis even without the presence of cross-linking step because it has very dense amount of lignin domains. Second, the lignin is dissolved in high pH aqueous sodium hydroxide (NaOH) solution, and LNPs are precipitated when the nitric acid (HNO3) solution is added. Thus,

Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview

41

Fig. 8  The proposed mechanism of NL preparation (a) precipitation from Indulin AT (IAT) dissolved in ethylene glycol with HCl (aq.) and possible subsequent cross-linking and dialysis and by (b) precipitation from IAT dissolved in basic to acidic aqueous medium (Frangville et al. 2012; Chauhan 2020). (Copyright from Elsevier with License number 5265651361654)

the resulted NL has stability at acidic pH (above 5), and it was highly porous that consist of smaller lignin domains (Fig. 8b). Reactivity of NL particles is influenced by its origin, structure, chemical modification, and the functionalities present in it (Hussin et al. 2022). Owing to the complexity in the molecular structure of lignin and the steric hindrance associated with its structure, the reactivity of lignin is restricted (Adler 1977; Boerjan et al. 2003). Figure 9 displays several methods for the production of NL with different sizes and shapes. The modification of functionalities on the NL particle surface is possible by means of different chemical reactions like esterification, carboxymethylation, epoxidation, hydroxymethylation, sulfonation, and oxidation (Adler 1977; Gosselink et al. 2004a, b; Stewart 2008; Toledano et al. 2010; Tomani 2010; Vahabi et al. 2021; Hussin et  al. 2022). Unmodified NL particles contain phenolic and aliphatic hydroxyl groups, uncondensed guaiacyl groups, and carbonyl groups (Hussin et al. 2022). These functional groups on lignin can promote its insertion into bio-based thermosetting and thermoplastic polymers for wood adhesives. The NL particles can be incorporated into the polymer matrix of various wood adhesives without any chemical modifications. However, etherification and esterification of NL particles make the −OH group more accessible (Hussin et al. 2022). Compared with technical lignin, NL particles have better interaction with polymer matrices due to its small size and are capable of enhancing the performance of the composite. The NL particles of spherical shape can disperse well in water and retain its dispersed state for about 2 months without settling down. Moreover, ultrasonication irradiation helps in ensuring the formation of homogenous dispersion without

42

P. Antov et al.

Fig. 9  Methods for the production of nanolignin with different sizes and shapes (Hussin et al. 2022). (Copyright from Elsevier with License number 5272370451911)

chemical treatment (Vahabi et al. 2021). The prepared NL particles have widespread applications in the field of polymeric nanocomposites having different polarity, and the functionalization enhances the dispersion in the polymer matrix due to improved compatibility. With respect to the application of NL in wood adhesives, researchers have mainly focused on the use of lignin as a partial or complete substitute of phenol in the

Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview

43

synthesis of lignin–phenol–formaldehyde (LPF) resins because of the similar chemical structures (El Mansouri et al. 2011; Song et al. 2016; Yang et al. 2019). The use of lignin as a reinforcing agent or filler in phenolic composites has not been widely reported. The morphology of the LPF resins was observed using SEM to establish how the foam is affected by the NL weight fraction and blowing agent amount. SEM images of foams formulated with 0.05, 5, and 9.95 wt% of NL and 2.5 wt% blowing agent, as well as the cell size distributions of the LPF resins, are shown in Fig. 10 (Del Saz-Orozco et al. 2012). As the NL weight fraction increased, the mean cell size decreased. For example, the mean cell size for foams formulated with 9.95 wt% of NL was 0.066 mm, whereas the mean cell size of foams formulated with 0.05 wt% of NL was 0.086 mm. Introducing NL into conventional polymeric matrix such as poly(vinyl alcohol) (PVA) to form transparent films, which exhibit excellent antioxidant functionalities (reached ~160 μm mol Trolox g−1 with 4 wt% of LNPs), has been reported comprehensively (Chauhan 2020; Tian et  al. 2017). Simultaneously, high number of phenolic hydroxyl groups present in the shell region of the NL enabled an excellent interfacial adhesion with PVA matrix via the formation of hydrogen bonding network, which further improved the mechanical and thermal performances of the fabricated PVA/NL nanocomposite films. The antioxidant properties and high dissolubility were found in the NL (Fig.  11). Based on this study, the PVA/NL blends could also be used as wood adhesive by forming films in the glue lines of wood-based panels, which could provide excellent interfacial adhesion via hydrogen bonding. In another work, the colloidal NL was fabricated by dropwise adding the alkali solution of NL into the poly (diallyldimethylammonium chloride) (PDADMAC) (Jiang et al. 2013). The formed NL was positively charged and water-soluble until the mass ratio of lignin to PDADMAC exceeded stoichiometric point. However, the natural rubber latex (NRL) particles were natively charged at the pH of 12, as the protein molecules absorbed on the surface of NRL particles contained carboxylic and amino groups and the carboxylic groups would be ionized at that pH. When the NL solution were added into NRL, the natively charged NRL were subsequently adsorbed onto the positively charged NL via electrostatic self-assembly, which would suppress the aggregation of lignin and finally resulted in homogeneous distribution of lignin in NR matrix (Fig. 12). However, excess PDADMAC adsorbed onto NL is unnecessary. If present in excess, it will prematurely flocculate the NRL and reduce the loading of NL incorporated into rubber matrix. The particle size of NL is around 180–400 nm (Jiang et al. 2013). Based on this study, the NL/NRL blends could also be used as wood adhesive by forming films in the glue lines of wood-based panels, which could provide excellent interfacial adhesion via electrostatic self-assembly.

44

P. Antov et al.

Fig. 10  SEM images for LPF resins formulated at (a) 0.05, (b) 5, (c) 9.95 wt% of nanolignin and 2.5 wt% blowing agent and (d) their respective cell size distributions; (e) 1.09, (f) 2.5, (g) 3.91 wt% blowing agent and 5 wt% of nanolignin and (h) their respective cell size distributions (Del Saz-­ Orozco et al. 2012). (Copyright from Elsevier with License number 5265650455695)

Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview

45

Fig. 11  Synthetic fabrication of NL and PVA/NL film (Chauhan 2020; Tian et  al. 2017). (Copyright from Elsevier with License number 5265651361654)

Fig. 12  Schematic illustration of process for NL/NRL nanocomposites (Jiang et al. 2013)

4 Nanoclay Application in Bio-Based Wood Adhesives Nanoclay has long been regarded as a viable reinforcing agent for improving the characteristics of wood adhesives. Nanoclay was mixed into phenolic resin and employed in the impregnation process to improve the performance of low density wood. After the addition of nanoclay, the treated wood was reported to have increased strength qualities (Lu and Zhao 2008; Cai et al. 2008). However, dispersion of nanoclay in the resin matrix is a critical issue when it comes to its inclusion into phenolic resin. Leemon et al. (2015) used sonification to disseminate nanoclay into phenolic resin. The scientists discovered that exfoliation of nanoclay occurred during the lack of a peak in the XRD plot (Fig.  13). A TEM investigation was

46

P. Antov et al.

Fig. 13  XRD plot of nanoclay (a) 20% PF concentration, (b) 15% PF concentration, and (c) 10% PF concentration (Leemon et  al. 2015) (with permission from Springer, License number: 5280550727649)

Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview

47

Fig. 14  TEM characterization of (a) 20% resin/1.5% nanoclay, (b) 15% resin/1.5% nanoclay, and (c) 10% resin/1.5% nanoclay. Gray clouds represent LmwPF resin, and the dark clouds and lines represent the clay contents (Leemon et al. 2015) (with permission from Springer, License number: 5280550727649)

performed to validate the exfoliation state of the mixtures. The findings of the analysis are shown in Fig.  14. There were two separate bands of cloud, dark (black arrows) and gray (white arrows). The findings indicated that the resin had penetrated the nanoclay inter-gallery in an exfoliated form. The study demonstrated that nanoclay may be dispersed evenly in a resin matrix. It brings up a lot of opportunities for using nanoclay as a bio-based adhesive reinforcing agent. In polymers, O’Donnell et al. (2004) have reported that the small concentrations of nanoclays improve barrier and mechanical properties. The modification of bio-­ based polymers by reinforcing nanoclays has been proved to regain the barrier, thermal properties, and stiffness that have been lost as a result of the addition of bio-resin and also enhanced the toughness-stiffness balance (Liu et al. 2005; Li et al. 2015). Thus, reinforcement of nanoclay in a bio-blend creates a polymer nanocomposite that has the same or greater properties as the pristine polymer and could be used in several different applications. Fiber-reinforced composites benefit greatly from layered silicate nanocomposites, not only because of value-added qualities it provides but also because of improvement in neat resin. Haq et al. (2008) stated that a perfect balance for an effective composite has been achieved by the clay when it comes to toughness and stiffness. Adding clay to the bio-based composite may also have a synergistic impact between scales by protecting natural fibers from contacting the moisture. The tensile strength and ductility of the resin systems decrease as the nanoclay concentration rises, leading to higher stiffness and brittleness (Dutta and Karak 2005; Haq et al. 2008; Wang et al. 2011). In general, bioresin and nanoclay

48

P. Antov et al.

Table 3  Types of commercial modified nanoclays Producer Southern clay products (the United States)

Clay Cloisite 10A Cloisite 15A Cloisite 20A Cloisite 25A Cloisite 30B

Nanocor Inc. (the United States)

Co-op chemicals (Japan)

Sud-Chemie (Germany)

Cloisite 93A Cloisite Na+ Nanomer I.28E Nanomer I.30E MAE MTE MEE MPE Optigel EX0255 Nanofil 804

Modifier agent Dimethyl, benzyl, hydrogenated tallow, quaternary ammonium Dimethyl, dihydrogenated tallow, quaternary ammonium Dimethyl, dihydrogenated tallow, quaternary ammonium Dimethyl, dihydrogenated tallow, 2-ethylhexyl quaternary ammonium Methyl, tallow, bis-2-hydroxyethyl, quaternary ammonium Methyl, dehydrogenated tallow ammonium Sodium montmorillonite Octadecyl trimethyl ammonium Octadecylamine Dimethyl dialkyl (tallow) ammonium Trioctyl methyl ammonium Methyl bis-2-hydroxyethyl coco quaternary ammonium Polyoxy propylene methyl diethyl ammonium Sodium montmorillonite Stearyl diethoxyamine

act in collaboration to produce composites that have an excellent stiffness-­toughness ratio (Dutta and Karak 2005; Wang et al. 2011; Haq et al. 2011). However, generally, montmorillonite (MMT) nanoclay is hydrophilic and is not compatible with most of the polymers, which are hydrophobic. The surface modification of MMT by organic ammonium salts and amino acids can improve the nanoclays’ performance in polymer composites. The lists of commercial modified nanoclays’ or organoclays’ products with their modifier agents are presented in Table 3. Furthermore, low concentrations of nanoclays have been shown to increase the polymer’s ablation resistance, flammability, and barrier properties (Haq et  al. 2008, 2009; Li et al. 2015). Platelets with a thickness of less than one nanometer have been found in nanoclays or layered silicates. These structures are defined by their high aspect ratio and large surface areas. Platelets in stacks separate when the polymer/resin penetrates the platelets. The clay’s intercalated and exfoliated morphologies are determined by the penetration level of the clay. The intercalated morphologies permit the polymer to penetrate between the clay platelets, such that the clay platelet stacks/galleries increase but do not split (Haq et al. 2009). The polymer-clay resin system efficacy is dependent on the clay’s morphology, which is affected by the processing method and functionalization. However, clay’s chemistry has an effect on the quality of the intercalation/exfoliation dispersion of nanoclay

Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview

49

Fig. 15  Schematic illustration of various types layered silicate dispersion in polymer matrix

(Ngo et al. 2009; Li et al. 2015). The exfoliated, interacted, or tactoid form of nanoclays in polymer resin as depicted in Fig. 15 is depending on the type of polymer matrix used, amount of organic modifier, types of nanoclay, and synthesis method (Hafiz 2013). Nanocomposites from bio-based vinyl ester (BVE) and several kinds of nanoclay were examined by Ngo et  al. (2009). Specifically, Southern Clay Products, Inc. provided three different kinds of modified nanoclay for the study: C10A, C20A, and C30A. In comparison with BVE-C10A and BVE-C30B, X-ray diffraction patterns suggest that C20A exhibits higher intercalation/exfoliation in the BVE matrix. Figure 16 shows that with BVE-C20A, the peak in clay inclusion intensity is nearly disappeared. The modification of nanoclay had been done to some level, since the nanoclay’s chemistry is crucial to assure the reinforcing effects. It is not only the type of nanoclay that has an impact on the properties of the bioresin but also the proportion of nanoclay inclusions. The toughness of nanocomposites can be improved by adding nanoclay, although it is dependent on how well the clay platelets have been exfoliated and dispersed (Nair et  al. 2002). In another work, the effects of different content and types of nanoclay on bioepoxy-clay nanocomposites mechanical properties were examined by Basara et al. (2005). Cloisite 30B (organically modified) and Cloisite Na+ (pristine) nanoclays were used in this study. It was found that nanocomposites reinforced with 0.5  wt% of Cloisite 30B showed enhanced impact strength up to 137% over 0.5  wt% pristine nanoclay (Table  4). Studying the impact of different clay concentrations, Haq et al. (2008) investigated the free clay and 1.5 wt% of modified nanoclay effect in an unsaturated polyester (UPE)/epoxidized methyl soyate (EMS) mix polymer. Nanoclay reinforcement of 1.5 wt% increased the initial stiffness while decreasing the elongation at break and tensile strength of the neat UPE slightly. Bioresin (EMS) added to a UPE, on the

50

P. Antov et al.

Fig. 16  X-ray diffraction for bio-based vinyl ester nanocomposite with different nanoclays (Ngo et al., 2009)

Table 4  Mechanical properties of different types bio-adhesive/nanoclay composites Bio-­ adhesives Epoxy

Epoxy

UPE UPE Corn starch Epoxidized soybean oil Oxidized starch Corn starch

Nanoclay Types of content nanoclay (%) Cloisite Na+ 3

Tensile strength (MPa) 44

Tensile modulus (MPa) 2700

Impact strength (J/m) 31

Cloisite 30B 1.34 (TCN Nanocor) 1.34 (TDI-BA) Cloisite 30B Cloisite 30B MMT Cloisite 30B

3 5

59 42

2600 –

36 –

5

57

–

–

1.5 5 5 8

25 15 11 5

6000 5000 – 4000

38 12 –

Haq et al. (2008) Haq et al. (2011) Li et al. (2015) Liu et al. (2005)

BNT

5

1.18

–

–

Lubis et al. (2021)

TMI-BNT 5 Alumina 5 silicate (MMT K10)

1.25 13

– –

– –

Reference (s) Basara et al. (2005) Feng et al. (2002)

Vishnuvarthanan et al. (2021)

TDI tolylence 2, 4-diisocynate; BA bisphenol A; UPE unsaturated polyester; MMT montmorillonite; BNT bentonite; TMI Transition metal ion

other hand, exhibits the opposite properties. Still, it seems that addition of 10% EMS resulted in larger tensile modulus reduction than addition of 1.5 wt% nanoclay offered in terms of recovery. Furthermore, Haq et al. (2011) investigated the impact of increasing the modified nanoclays’ content in epoxidized methyl linseedate (EML)/UPE composites. In every resin system, nanoclay inclusions of 2.5 and 5.0 wt% are used to distinguish the loadings. The nanocomposite’s toughness and tensile strength are reduced by the addition of nanoclay. More brittle

Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview

51

nanocomposites are produced as a result of the stiffening effect of the nanoclay. Haq et al. (2011) further stated that the best material combination that leads in excellent processing and various properties meant that total recovery by nanoclay loading (at 5  wt%) was achievable for most properties on the bio-based polymer with EML content up to 10%, whereas partial recovery at 20% EML loadings and typically nanoclay reinforcement had less or no impact on bio-based polymers with 30% EML content. In another study, Vishnuvarthanan et al. (2021) used alumina silicate nanoclay to modify corn starch-based bio adhesives and observed the nanoclay influence on barrier and adhesive properties. The authors found that the addition of 5 wt% of nanoclay into the corn starch adhesive demonstrated excellent barrier and adhesive properties over neat corn starch adhesive. Lubis et al. (2021) reported the effect of pristine and modified nanoclay loading into oxidized starch adhesives, and they observed that incorporation of 5  wt% of modified nanoclay into adhesive resulted in a significant improvement in strength and low formaldehyde emissions compared with pristine nanoclay. While studying the impact of high nanoclay loadings in epoxidized soybean oil (ESO), Liu et al. (2005) discovered that adding nanoclay to the ESO matrix up to 8 wt% increased the stiffness of the material significantly. However, when clay content was increased at 10 wt%, the storage modulus and strength of the material decreased (Li et al. 2015). These nanoclay layers contribute to the immobilized or partially immobilized occurrence of polymer phases because of their high stiffness. The direction of the silicate layer may also have an impact on the reinforcing effects. Young’s modulus, on the other hand, decreases with increasing clay content, as seen in Fig.  17 (transmission electron microscopy (TEM) images). This can be ascribed to the unavoidable aggregation of layers. Moreover, nanoclay had an impact on the polyester resin’s curing profile in contrast to its mechanical and processing properties. In their study, Poorabdollah et al. (2011) used a basic phenomenon logical analysis to examine the influence of nanoclay on each curing process. The kinetic model for a dynamic curing process with a

Fig. 17  TEM micrographs of epoxidized soybean oil (ESO)/clay nanocomposites containing (a) 5.0 wt%, (b) 8.0 wt%, and (c) 10.0 wt% clay content. (Reproduced from (Liu et al. 2005) with permission from Elsevier, License number: 5267530844011)

52

P. Antov et al.

constant heating rate can be described as follows by taking the maximal response rate at time t > 0:



dα  −E  m = A exp   α (1 − α ) n dt  RT  (1)

“where A is a pre-exponential factor that represents the number of collisions between reactive components per unit time, E is the activation energy, R is the gas constant, T is the absolute temperature, and (m + n) is the order of the reaction.” Differential scanning calorimetry (DSC) testing was used to compare a pure UPE resin with an organically modified clay (OMC)-containing unsaturated polyester resin at a 5 °C/min temperature rate. Poorabdollah et al. (2011) reported that the unsaturated polyester/OMC reacted at a higher rate than the neat UPE, and the reaction started at lower temperatures. In another study, the impact of modified MMT in bio-epoxy-based nanocomposites was studied by Feng et  al. (2002). Unmodified and modified nanoclay were used in this study. For modified nanoclay nanocomposites, the thermal stability and storage modulus found improved at higher temperature over the matrix glass transition temperature (Tg), according to DSC results.

5 Challenges and Future Prospects The future prospects of bio-based resin are bright, as the global wood adhesives market has grown in recent years. According to Grand View Research (2019), the global wood adhesives market will be worth USD 6.34 billion by 2025, growing at a compound annual growth rate (CAGR) of 4.7% during the forecast period. The growing demand from engineered wood-based panel manufacturers is a significant market driver. Because of their environmentally friendly characteristics, bio-based adhesives, specifically soy-based adhesives, are expected to grow at the fastest rate, with a CAGR of 7.5% from 2019 to 2025. However, one of the major constraints of promoting these bio-based adhesives is their cost competitiveness with formaldehyde-­based adhesives. These bio-based adhesives have become more economically attractive due to the technology advancement and the spiking price of methanol in formaldehyde production. Nonetheless, their inferior properties necessitated reinforcement, in this case nanocellulose, which resulted in higher production costs for the producers. The current major impediments to the further development of nanocellulose are its limited commercial supply and relatively high manufacturing cost. Given recent promising developments, this problem should be resolvable (Nelson et al. 2016). Another challenge is that nanocellulose may affect the curing kinetics of adhesive, preventing water from evaporating during the pressing process, which can be technologically disadvantageous and reduce productivity (Mahrdt et  al. 2016). Furthermore, changes in viscosity after nanocellulose addition are a problem that

Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview

53

must be addressed because most wood-based panels require sprayable products during adhesive application.

6 Conclusion Bio-sourced nanomaterials represent an abundant and renewable natural feedstock for development of eco-friendly and sustainable materials for a wide range of industrial applications, including wood adhesives. This chapter highlighted the recent progress and applications of nanocellulose, nanolignin, and nanoclay as reinforcing agents and natural binders in wood adhesives. Depending on the type of nanomaterial used, its chemical modification and compatibility with the bio-based resin and various properties of wood adhesives, e.g., water resistance, bonding strength, and thermal stability, were enhanced even with the addition of small amounts of nanomaterials. Due to their intrinsic reinforcing abilities, the use of bio-sourced nanomaterials in wood adhesives could significantly increase the physical and mechanical properties of manufactured wood-based composites and reduce the free formaldehyde emissions as well. Structural modifications, aimed at achieving new functionalities of green nanomaterials used in wood adhesive applications, will facilitate the transition of wood-based panel industry toward a low-carbon, circular bioeconomy and decrease its dependence on synthetic petroleum-derived materials. Markedly, in order to fully employ the inherent characteristics of nanomaterials and to expand their application in the synthesis of wood adhesives, future research is needed to further reveal the properties of nanomaterials by efficient characterization techniques, thus promoting their wider industrial application in the field of wood adhesives.

References Abdelmoula M, Ben Hlima H, Michalet F, Bourduche G, Chavant JY, Gravier A, Delattre C, Grédiac M, Mathias JD, Abdelkafi S, Michaud P, de Baynast H (2021) Chitosan-based adhesive: optimization of tensile shear strength in dry and wet conditions. Polysaccharides 2(1):110–120 Adler E (1977) Lignin chemistry: past, present and future. Wood Sci Technol 11:169–218 Akinyemi BA, Kolajo TE, Adedolu O (2022) Blended formaldehyde adhesive bonded particleboards made from groundnut shell and rice husk wastes. Clean Technol Environ: 1–10. Amini E, Tajvidi M, Gardner DJ, Bousfield DW (2017) Utilization of cellulose nanofibrils as a binder for particleboard manufacture. BioResources 12:4093–4110 Ang AF, Ashaari Z, Lee SH et al (2019) Lignin-based copolymer adhesives for composite wood panels – a review. Int J Adhes Adhes 95:102408 Antov P, Jivkov V, Savov V, Simeonova R, Yavorov N (2020a) Structural application of eco-­ friendly composites from recycled wood fibres bonded with magnesium lignosulfonate. Appl Sci 10:7526

54

P. Antov et al.

Antov P, Savov V, Neykov N (2020b) Reduction of formaldehyde emission from engineered wood panels by formaldehyde scavengers - a review. In: Proceedings of the 13th International Scientific Conference Wood EMA 2020 and 31st International Scientific Conference ICWST 2020 Sustainability of Forest-Based Industries in the Global Economy, Vinkovci, Croatia, 28–30 September 2020, pp. 7–11 Antov P, Savov V, Krišt’ák L, Réh R, Mantanis GI (2021a) Eco-friendly, high-density fiberboards bonded with urea-formaldehyde and ammonium lignosulfonate. Polymers 13:220 Antov P, Savov V, Trichkov N, Krišťák Ľ, Réh R, Papadopoulos AN, Taghiyari HR, Pizzi A, Kunecová D, Pachikova M (2021b) Properties of high-density fiberboard bonded with urea–formaldehyde resin and ammonium lignosulfonate as a bio-based additive. Polymers 13(16):2775 Arias A, Feijoo G, Moreira MT (2021a) Evaluation of starch as an environmental-friendly bioresource for the development of wood bioadhesives. Molecules 26:4526 Arias A, González-Rodríguez S, Vetroni Barros M, Salvador R, de Francisco AC, Piekarski CM, Moreira MT (2021b) Recent developments in bio-based adhesives from renewable natural resources. J Clean Prod 314:127892 Arias A, Entrena-Barbero E, Feijoo G, Maria Teresa Moreira MT (2022) Sustainable non-­ isocyanate polyurethanes bio-adhesives for engineered wood panels are revealed as promising candidates to move from formaldehyde-based alternatives. J Environ Chem Eng 10:107053 Aristri MA, Lubis MAR, Iswanto AH, Fatriasari W, Sari RK, Antov P, Gajtanska M, Papadopoulos AN, Pizzi A (2021a) Bio-based polyurethane resins derived from tannin: source, synthesis, characterisation, and application. Forests 12(11):1516 Aristri MA, Lubis MAR, Yadav SM et al (2021b) Recent developments in lignin- and tannin-based non-isocyanate polyurethane resins for wood adhesives—a review. Appl Sci 11:4242 Ayrilmis N, Lee YK, Kwon JH, Han TH, Kim HJ (2016) Formaldehyde emission and VOCs from LVLs produced with three grades of urea-formaldehyde resin modified with nanocellulose. Build Environ 97:82–87 Bandara N, Esparza Y, Wu J (2017) Exfoliating nanomaterials in canola protein derived adhesive improves strength and water resistance. RSC Adv 7:6743–6752 Barari B, Omrani E (2016) Mechanical, physical and tribological characterization of nano-­ cellulose fibers reinforced bio-epoxy composites: An attempt to fabricate and scale the ‘Green’ composite. Carbohydr Polym 147:282–293 Barbu MC, Lohninger Y, Hofmann S, Kain G, Petutschnigg A, Tudor EM (2020a) Larch Bark as a formaldehyde scavenger in thermal insulation panels. Polymers 12(11):2632 Barbu MC, Sepperer T, Tudor EM, Petutschnigg A (2020b) Walnut and Hazelnut Shells: untapped industrial resources and their suitability in lignocellulosic composites. Appl Sci 10:6340 Barkane A, Kampe E, Platnieks O, Gaidukovs S (2021) Cellulose nanocrystals vs. cellulose nanofibers: a comparative study of reinforcing effects in UV-cured vegetable oil nanocomposites. Nanomaterials 11:1791 Basara C, Yilmazer U, Bayram G (2005) Synthesis and characterization of epoxy based nanocomposites. J Appl Polym Sci 98:1081–1086 Beisl S, Friedl A (2017) Miltner A. Lignin from micro- To nanosize, Applications Bekhta P, Sedliačik J, Jones D (2018) Effect of short-term thermomechanical densification of wood veneers on the properties of birch plywood. Eur J Wood Wood Prod 76(2):549–562 Bekhta P, Sedliačik J, Bekhta N (2020) Effect of veneer-drying temperature on selected properties and formaldehyde emission of birch plywood. Polymers 12(3):593 Bekhta P, Noshchenko G, Réh R, Kristak L, Sedliačik J, Antov P, Mirski R, Savov V (2021a) Properties of eco-friendly particleboards bonded with lignosulfonate-urea-formaldehyde adhesives and pMDI as a crosslinker. Materials 14(17):4875 Bekhta P, Sedliačik J, Noshchenko G, Kačík F, Bekhta N (2021b) Characteristics of Beech Bark and its effect on properties of UF adhesive and on bonding strength and formaldehyde emission of plywood panels. Eur J Wood Prod 79:423–433 Boerjan W, Ralph J, Baucher M (2003) Lignin biosynthesis. Annu Rev Plant Biol 54:519–546

Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview

55

Boran S, Usta M, Ondaral S, Gümüşkaya E (2012) The efficiency of tannin as a formaldehyde scavenger chemical in medium density fiberboard. Compos Part B 43(5):487–2491 Borrero-López AM, Valencia C, Domínguez G, Eugenio ME, Franco JM (2021) Rheology and adhesion performance of adhesives formulated with lignins from agricultural waste straws subjected to solid-state fermentation. Ind Crop Prod 171:113876 Brigham C (2018) Biopolymers: biodegradable alternatives to traditional plastics. In: Török B, Dransfield T (eds) Green chemistry. Elsevier, Amsterdam, pp 753–770 Bütün Buschalsky FY, Mai C (2021) Repeated thermo-hydrolytic disintegration of medium density fibreboards (MDF) for the production of new MDF. Eur J Wood Prod 79:1451–1459 Buyuksari U, Ayrilmis N, Avci E, Koc E (2010) Evaluation of the physical, mechanical properties and formaldehyde emission of particleboard manufactured from waste stone pine (Pinus pinea L.) cones. Bioresour Technol 101:255–259 Cai X, Riedl B, Wan H, Zhang SY (2008) The impact of interphase between wood, melamine-­ ureaformaldehyde and layered silicate on the performance of wood polymer nanocomposites. Compos Part A 39:727–737 Camlibel O (2020) Mechanical and formaldehyde-related properties of medium density fiberboard with zeolite additive. BioResources 15(4):7918–7932 Chauhan PS (2020) Lignin nanoparticles: Eco-friendly and versatile tool for new era. Bioresour Technol Reports 9:100374 Chen N, Zheng P, Zeng Q, Lin Q, Rao J (2017) Characterization and performance of soy-based adhesives cured with epoxy resin. Polymers 9(10):514 Chen X, Xi X, Pizzi A, Fredon E, Du G, Gerardin C, Amirou S (2020) Oxidized demethylated lignin as a bio-based adhesive for wood bonding. J Adhes 97:873–890 Chen X, Pizzi A, Xi X, Zhou X, Fredon E, Gerardin C (2021) Soy protein isolate non-isocyanates polyurethanes (NIPU) wood adhesives. J Renew Mater 9(6):1045–1057 Chen X, Pizzi A, Fredon E, Gerardin C, Zhou X, Zhang B, Du G (2022) Low curing temperature tannin-based non-isocyanate polyurethane (NIPU) wood adhesives: preparation and properties evaluation. Int J Adhes Adhes 112:103001 Cheng HN, Kilgore K, Ford C, Fortier C, Dowd MK, He Z (2019) Cottonseed protein-based wood adhesive reinforced with nanocellulose. J Adhes Sci Technol 33:1357–1368 Costa NA, Pereira J, Ferra J, Cruz P, Martins J, Magalhães FD, Mendes A, Carvalho LH (2013a) Scavengers for achieving zero formaldehyde emission of wood-based panels. Wood Sci Technol 47:1261–1272 Costa NA, Pereira J, Ferra J, Cruz P, Martins J, Magalhães FD, Mendes A, Carvalho LH (2013b) Sodium metabisulphite as a scavenger of air pollutants for wood-based building materials. Int Wood Prod J 4(4):242–247 Costa NA, Ohlmeyer M, Ferra J, Magalhães F, Mendes A, Carvalho L (2014) The influence of scavengers on VOC emissions in particleboards made from pine and poplar. Eur J Wood Prod 72:117–121 Cui J, Lu X, Zhou X, Chrusciel L, Deng Y, Zhou H, Zhu S, Brosse N (2015) Enhancement of mechanical strength of particleboard using environmentally friendly pine (Pinus pinaster L.) tannin adhesives with cellulose nanofibers. Ann For Sci 72:27–32 Dammer L, Bowyer C, Breitmayer E, Eder A, Nanni S, Allen B, Carus M, Essel R (2016) Mapping study on cascading use of wood products, WWF Technical Report. Available online at https:// wwfeu.awsassets.panda.org/downloads/wwf_mondi_cascading_use_of_wood_final_web.pdf. Accessed 6 Mar 2022 Darmawan S, Sofyan K, Pari G, Sugiyanto K (2010) Effect of activated charcoal addition on formaldehyde emission of medium density fibreboard. J For Res 7(2):100–111 de Cademartori PHG, Artner MA, de Freitas RA, Magalhães WLE (2019) Alumina nanoparticles as formaldehyde scavenger for urea-formaldehyde resin: Rheological and in-situ cure performance. Compos Part B 176:107281

56

P. Antov et al.

Del Saz-Orozco B, Oliet M, Alonso MV et al (2012) Formulation optimization of unreinforced and lignin nanoparticle-reinforced phenolic foams using an analysis of variance approach. Compos Sci Technol 72:667–674 Dunky M (2003) Chapter 47: Adhesives in the wood industry. In: Pizzi A, mittal k l (eds) Handbook of adhesive technology. Marcel Dekker, New York, pp 872–941 Dunky M (2020) Wood adhesives based on natural resources: a critical review Part III. Tannin- and Lignin-based adhesives. Rev Adhes Adhes 8:379–525 Dutta S, Karak N (2005) Synthesis, characterization of poly (urethane amide) resins from Nahar seed oil for surface coating applications. Prog Org Coat 53:147–152 El Mansouri NE, Pizzi A, Salvadó J (2006) Lignin-based wood panel adhesives without formaldehyde. Holz Roh Werkst 65:65 El Mansouri NE, Yuan Q, Huang F (2011) Characterization of alkaline lignins for use in phenol-­ formaldehyde and epoxy resins. BioResources 6:2647–2662 Eom YG, Kim JS, Kim S, Kim JA, Kim HJ (2006) Reduction of formaldehyde emission from particleboards by bio-scavengers. Mokchae Konghak 34(5):29–41 Esmailpour A, Taghiyari HR, Majidi R, Morrell JJ, Mohammad-Panah B (2019) Nano-wollastonite to improve fire retardancy in medium-density fiberboard (MDF) made from wood fibers and camel-thorn. Wood Mater Sci Eng. https://doi.org/10.1080/17480272.2019.1641838 Esposito L, Ciannamea EM, Solaberrieta I, Piter JC, Ruseckaite RA, Stefani PM (2022) Tannin-­ modified soybean protein concentrate for wood adhesive. J Appl Res Technol Eng 3(1):1–7 Feng W, Ait-kadi A, Riedl B (2002) Polymerization compounding: epoxy-montmorillonite nanocomposites. Polym Eng Sci 42:1827–1835 Foti D, Voulgaridou EE, Karastergiou S, Taghiyari HR, Papadopoulos AN (2022) Physical and mechanical properties of eco-friendly composites made from wood dust and recycled polystyrene. J Renew Mater 10(1):75 Forest Product Statistics (2021) Available online: https://www.fao.org/forestry/statistics/80938/en/ (accessed on 6 March 2022) Frangville C, Rutkevičius M, Richter AP et al (2012) Fabrication of environmentally biodegradable lignin nanoparticles. ChemPhysChem 13:4235–4243 Frazier CE (2003) Chapter 33: Isocyanate wood binders. In: Pizzi A, Mittal KL (eds) Handbook of adhesive technology, 2nd edn. Marcel Dekker, New York, pp 681–694 Frihart CR (2015) Wood Adhesives: Past, Present, and Future. For Prod J 65:4–8 Frihart CR, Satori H (2013) Soy flour dispersibility and performance as wood adhesive. J Adhes Sci Technol 27:2043–2052 Gagnon M, Roy C, Riedl B (2004) Adhesives made from isocyanates and pyrolysis oils for wood composites. Holzforschung 58:400–407 Galland S, Leterrier Y, Nardi T, Plummer CJG, Månson JAE, Berglund LA (2014) UV-cured cellulose nanofiber composites with moisture durable oxygen barrier properties. J Appl Polym Sci 2014:131 Gao Q, Li J, Shi SQ, Liang K, Zhang X (2012) Soybean meal-based adhesive reinforced with cellulose nano-whiskers. BioResources 7:5622–5633 Ghahri S, Pizzi A (2018) Improving soy-based adhesives for wood particleboard by tannins addition. Wood Sci Technol 52:261–279 Ghahri S, Bari E, Pizzi A (2021) The challenge of environment-friendly adhesives for bio-­ composites. In: Jawaid M, Khan TA, Nasir M, Asim M (eds) Eco-friendly adhesives for wood and natural fiber composites; composites science and technology. Springer, Singapore Ghahri S, Pizzi A, Hajihassani R (2022) A study of concept to prepare totally biosourced wood adhesives from only soy protein and tannin. Polymers 14(6):1150 Ghani A, Paiman B, Lee SH, Zaidon A (2019) Physico-mechanical properties and formaldehyde emission of rubberwood particleboard made with UF resin admixed with ammonium and aluminium-based hardeners. Pertanika J Sci Technol 27(1):473–488 Gillela S, Yadav SM, Sihag K, Lubis MAR, Wibowo ES, Negi A, Iswanto AH, Antov P, Kristak L (2022) A review on Lantana camara lignocellulose fiber-reinforced polymer composites. Biomass Conv Bioref. https://doi.org/10.1007/s13399-­022-­02402-­7

Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview

57

Goodsell JE, Moon RJ, Huizar A, Pipes RB (2014) A strategy for prediction of the elastic properties of epoxy-cellulose nanocrystal-reinforced fiber networks. Nord Pulp Paper Res J 29:85–94 Gosselink RJA, Abächerli A, Semke H et al (2004a) Analytical protocols for characterisation of sulphur-free lignin. Ind Crops Prod 19:271–281 Gosselink RJA, Snijder MHB, Kranenbarg A et  al (2004b) Characterisation and application of NovaFiber lignin. Ind Crops Prod 20:191–203 Grand View Research (2019) Wood adhesives market size worth $6.34 billion by 2025 | CAGR: 4.7%. https://www.grandviewresearch.com/press-­release/global-­wood-­adhesives-­market. Assessed 23 Mar 2022. Gu Y, Cheng L, Gu Z, Hong Y, Li Z, Li C (2019) Preparation, characterization and properties of starch-based adhesive for wood-based panels. Int J Biol Macromol 134:247–254 Hafiz AA (2013) Synthesis and characterization of eva-cloisite clay nanocomposites. Master of Science in Nanotechnology, The American University in Cairo, Cairo Hagel S, Joy J, Cicala G, Saake B (2021) Recycling of waste MDF by steam refining: evaluation of fiber and paper strength properties. Waste Biomass Valor 12:5701–5713 Hakimi NM, Lee SH, Lum WC, Mohamad SF, Osman Al Edrus SS, Park BD, Azmi A (2021) Surface modified nanocellulose and its reinforcement in natural rubber matrix nanocomposites: A review. Polymers 13:3241 Haq M, Burgueño R, Mohanty AK, Misra M (2008) Hybrid bio-based composites from blends of unsaturated polyester and soybean oil reinforced with nanoclay and natural fibers. Compos Sci Technol 68:3344–3351 Haq M, Burgueño R, Mohanty AK, Misra M (2009) Bio-based unsaturated polyester/layered silicate nanocomposites: characterization and thermo-physical properties. Compos Part A 40:540–547 Haq M, Burgueño R, Mohanty AK, Misra M (2011) Bio-based polymer nanocomposites from UPE/EML blends and nanoclay: development, experimental characterization and limits to synergistic performance. Compos Part A 42:41–49 Hejna A, Marć M, Kowalkowska-Zedler D, Pladzyk A, Barczewski M (2021) Insights into the thermo-mechanical treatment of brewers’ spent grain as a potential filler for polymer composites. Polymers 13:879 Hematabadi H, Behrooz R, Shakibi A, Arabi M (2012) The reduction of indoor air formaldehyde from wood based composites using urea treatment for building materials. Constr Build Mater 28:743–746 Hemmilä V, Adamopoulos S, Karlsson O, Kumar A (2017) Development of sustainable bio-­ adhesives for engineered wood panels - a review. RSC Adv 7:8604–38630 Hornus M, Via KB, Gallagher T, Peresin MS (2020) Partial substitution of pMDI with lignin containing cellulose nanofibrils: low density oriented strand board. Wood Mater Sci Eng 16(6):391–396 Hosseinpourpia R, Adamopoulos S, Mai C, Taghiyari HR (2019) Properties of medium-density fiberboards bonded with dextrin-based wood adhesives. Wood Res 64:185–194 Hunt JF, Leng W, Tajvidi M (2017) Vertical density profile and internal bond strength of wet-­ formed particleboard bonded with cellulose nanofibrils. Wood Fiber Sci 49:413–423 Hussin MH, Appaturi JN, Poh NE, Latif NHA, Brosse N, Ziegler-Devin I, Vahabi H, Syamani FA, Fatriasari W, Solihat NN, Karimah A, Iswanto AH, Sekeri SH, Ibrahim MNM (2022) A recent advancement on preparation, characterization and application of nanolignin. Int J Biol Macromol 200:303–326 Ilyas RA, Aisyah HA, Nordin AH, Ngadi N, Zuhri MYM, Asyraf MRM, Sapuan SM, Zainudin ES, Sharma S, Abral H, Asrofi M, Syafri E, Sari NH, Rafidah M, Zakaria SZS, Razman MR, Majid NA, Ramli Z, Azmi A, Bangar SP, Ibrahim R (2022) Natural-Fiber-reinforced chitosan, chitosan blends and their nanocomposites for various advanced applications. Polymers 14(5):874 Irle M, Privat F, Couret L, Belloncle C, Déroubaix G, Bonnin E, Cathala B (2018) Advanced recycling of post-consumer solid wood and MDF. Wood Mater Sci Eng 11:1–5 Iždinský J, Vidholdová Z, Reinprecht L (2020) Particleboards from recycled wood. Forests 11:1166

58

P. Antov et al.

Jial P, Song F, Li Q, Xia H, Shu X, Zhou Y (2019) Recent development of cardanol based polymer materials: a review. J Renew Mater 7:601–619 Jiang C, He H, Jiang H et al (2013) Nano-lignin filled natural rubber composites: preparation and characterization. Express Polym Lett 7:480–493 Jiang W, Haapala A, Tomppo L, Pakarinen T, Sirviö JA, Liimatainen H (2018) Effect of cellulose nanofibrils on the bond strength of polyvinyl acetate and starch adhesives for wood. BioResources 13:2283–2292 Kaboorani A, Riedl B, Blanchet P, Fellin M, Hosseinaei O, Wang S (2012) Nanocrystalline Cellulose (NCC): a renewable nano-material for Polyvinyl Acetate (PVA) adhesive. Eur Polym J 48:1829–1837 Kalami S, Arefmanesh M, Master E, Nejad M (2017) Replacing 100% of phenol in phenolic adhesive formulations with lignin. J Appl Polym Sci 134:1–9 Kargarzadeh H, Huang J, Lin N, Ahmad I, Mariano M, Dufresne A, Thomas S, Galeski A (2018a) Recent developments in nanocellulose-based biodegradable polymers, thermoplastic polymers, and porous nanocomposites. Prog Polym Sci 87:197–227 Kargarzadeh H, Mariano M, Gopakumar D, Ahmad I, Thomas S, Dufresne A, Huang J, Lin N (2018b) Advances in cellulose nanomaterials. Cellulose 25:2151–2189 Karthäuser J, Biziks V, Mai C, Militz H (2021) Lignin and lignin-derived compounds for wood applications—a review. Molecules 26(9):2533 Kaur I, Misra BN, Sarkar A, Chauhan GS, Singh B (2002) Preparation and characterization of forest waste pine cellulosic fiber-UF resin based polymer composites. Sci Eng Compos Mater 10:437–451 Kawalerczyk J, Siuda J, Mirski R, Dziurka D (2020a) Hemp flour as a formaldehyde scavenger for melamine-urea-formaldehyde adhesive in plywood production. BioResources 15:4052–4064 Kawalerczyk J, Dziurka D, Mirski R, Szentner K (2020b) Properties of plywood produced with urea-formaldehyde adhesive modified with nanocellulose and microcellulose. Drv Ind 71:61–67 Khalaf Y, El Hage P, Mihajlova J, Bergeret A, Lacroix P, El Hage R (2021) Influence of agricultural fibers size on mechanical and insulating properties of innovative chitosan-based insulators. Constr Build Mater 287:123071 Kim S (2009) Environment-friendly adhesives for surface bonding of wood-based flooring using natural tannin to reduce formaldehyde and TVOC emission. Bioresour Technol 100:744–748 Kminiak R, Orlowski KA, Dzurenda L, Chuchala D, Banski A (2020) Effect of thermal treatment of birch wood by saturated water vapor on granulometric composition of chips from sawing and milling processes from the point of view of its processing to composites. Appl Sci 10(21):7545 Kojima Y, Kato N, Ota K, Kobori H, Suzuki S, Aoki K, Ito H (2018) Cellulose nanofiber as complete natural binder for particleboard. For Prod J 68:203–210 Köse K, Mavlan M, Youngblood JP (2020) Applications and impact of nanocellulose based adsorbents. Cellulose 27:2967–2990 Kristak L, Antov P, Bekhta P, Lubis MAR, Iswanto AH, Reh R, Sedliacik J, Savov V, Taghiyari H, Papadopoulos AN, Pizzi A, Hejna A (2022) Recent progress in ultra-low formaldehyde emitting adhesive systems and formaldehyde scavengers in wood-based panels: a review. Wood Mater Sci Eng. https://doi.org/10.1080/17480272.2022.2056080 Krišťáková S, Neykov N, Antov P, Sedliačiková M, Reh R, Halalisan AF, Hajdúchová I (2021) Efficiency of wood-processing enterprises - evaluation based on DEA and MPI: a comparison between Slovakia and Bulgaria for the period 2014–2018. Forests 12:1026 Kumar RN, Pizzi A (2019) Urea-formaldehyde resins. In: Adhesives for wood and lignocellulosic materials. Wiley-Scrivener Publishing, Hoboken, pp 61–100 Kunaver M, Medved S, Čuk N, Jasiukaitytė E, Poljanšek I, Strnad T (2010) Application of liquefied wood as a new particle board adhesive system. BioresTechnol 101(4):1361–1368 Łebkowska M, Radziwiłł MZ, Tabernacka A (2017) Adhesives based on formaldehyde—environmental problems. BioTechnol 98:53–65

Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview

59

Lee W, Liu C (2002) Preparation of liquefied bark based reso resin and its application to particle board. J Appl Polym Sci 87:1837–1841 Lee SH, Md Tahir P, Lum WC, Tan LP, Bawon P, Park BD, Osman Al Edrus SS, Abdullah UH (2020) A review on citric acid as green modifying agent and binder for wood. Polymers 12(8):1692 Leemon NF, Ashaari A, Uyup MKA, Bakar ES, Tahir PM, Saliman MAR, Ghani MA, Lee SH (2015) Characterisation of phenolic resin and nanoclay admixture and its effect on impreg wood. Wood Sci Technol 49:1209–1224 Lengowski EC, Bonfatti Júnior EA, Nishidate Kumode MM, Carneiro ME, Satyanarayana KG. (2019) Nanocellulose-reinforced adhesives for wood-based panels. In: Inamuddin, Thomas S, Kumar Mishra R, Asiri AM (eds), Sustainable polymer composites and nanocomposites, No. 167, Springer, Berlin, pp. 1001–1025 Lengowski EC, Bonfatti Júnior EA, Dallo R, Nisgoski S, Mattos JL, Prata JG (2021) Nanocellulose-reinforced phenol-formaldehyde resin for plywood panel production. Maderas Cienc Tecnol 23:1–10 Li Z, Wang J, Li C, Gu Z, Cheng L, Hong Y (2015) Effects of montmorillonite addition on the performance of starch-based wood adhesive. Carbohydr Polym 115:394–400 Li X, Chen M, Zhang J, Gao Q, Zhang S, Li J (2017) Physico-chemical properties of soybean meal-based adhesives reinforced by ethylene glycol diglycidyl ether and modified nanocrystalline cellulose. Polymers 9:463 Li K, Jin S, Li X, Li J, Shi SQ, Li J (2021) Bioinspired interface engineering of soybean meal-­ based adhesive incorporated with biomineralized cellulose nanofibrils and a functional aminoclay. Chem Eng J 421:129820 Liu Z, Erhan SZ, Xu J (2005) Preparation, characterization and mechanical properties of epoxidized soybean oil/clay nanocomposites. Polymer 46:10119–10127 Liu Z, Zhang Y, Wang X, Rodrigue D (2015) Reinforcement of lignin-based phenol-formaldehyde adhesive with nano-crystalline cellulose (NCC): curing behavior and bonding property of plywood. Mater Sci Appl 6:567 Lu WH, Zhao GJ (2008) Structure and characterization of Chinese fir (Cunninghamia lanceolata) wood/MMT intercalation nanocomposite (WMNC). Front For China 3:121–126 Lubis MAR, Hong MK, Park BD (2018) Hydrolytic removal of cured urea-formaldehyde resins in medium-density fiberboard for recycling. J Wood Chem. Technol 38:1–14 Lubis MA, Yadav SM, Park BD (2021) Modification of oxidized starch polymer with nanoclay for enhanced adhesion and free formaldehyde emission of plywood. J Polym Environ 29:2993–3003 Lubke H, Ihnát V, Kuňa V, Balberčák J (2020) A multi-stage cascade use of wood composite boards. Wood Res 65:843–854 Luo X, Shuai L (2020) Lignin-based adhesives. In: Green adhesives. Wiley, pp 25–56 Luo J, Zhou Y, Gao Q, Li J, Yan N (2020) From wastes to functions: a new soybean meal and bark-­ based adhesive. ACS Sustain Chem Eng 8(29):10767–10773 Mahrdt E, Pinkl S, Schmidberger C, van Herwijnen HW, Veigel S, Gindl-Altmutter W (2016) Effect of addition of microfibrillated cellulose to urea-formaldehyde on selected adhesive characteristics and distribution in particle board. Cellulose 23:571–580 Mantanis GI, Athanassiadou ET, Barbu MC, Wijnendaele K (2018) Adhesive systems used in the European particleboard, MDF and OSB industries. Wood Mater Sci Eng 13:104–116 Mariano M, El Kissi N, Dufresne A (2014) Cellulose nanocrystals and related nanocomposites:review of some properties and challenges. J Polym Sci Part B 52:791–806 Migneault S, Koubaa A, Riedl B, Nadji H, Deng J, Zhang T (2011) Potential of pulp and paper sludge as a formaldehyde scavenger agent in MDF resins. Holzforschung 65:403–409 Mirski R, Banaszak A, Bekhta P (2021) Selected properties of formaldehyde-free polymer-­ straw boards made from different types of thermoplastics and different kinds of straw. Materials 14:1216

60

P. Antov et al.

Miyashiro D, Hamano R, Umemura K (2020) A review of applications using mixed materials of cellulose, nanocellulose and carbon nanotubes. Nanomaterials 10(2):186 Mohammadinejad R, Karimi S, Iravani S, Varma RS (2016) Plant-derived nanostructures: types and applications. Green Chem 18:20–52 Mondal S (2017) Preparation, properties and applications of nanocellulosic materials. Carbohydr Polym 163:301–316 Moon RJ, Schueneman GT, Simonsen J (2016) Overview of cellulose nanomaterials, their capabilities and applications. JOM 68:2383–2394 Nair SV, Goettler LA, Lysek BA (2002) Toughness of nanoscale and multiscale polyamide-6, 6 composites. Polym Eng Sci 42(9):1872–1882 Ndiwe B, Pizzi A, Tibi B, Danwe R, Konai N, Amirou S (2019) African tree bark exudate extracts as biohardeners of fullybiosourced thermoset tannin adhesives for wood panels. Ind Crop Prod 132:253–268 Nelson K, Retsina T, Iakovlev M, van Heiningen A, Deng Y, Shatkin JA, Mulyadi A (2016) In: Madsen L, Svedberg E (eds) Materials research for manufacturing. Springer, Cham, pp 267–302 Ngo TD, Singh RP, Ton-That MT, Hoa SV (2009) The potential bio-based polymer and their nanocomposites for composites structure. In: 17th International Conference on Composite Materials (ICCM-17), Edinburgh International Convention Centre (EICC), Edinburgh Ninikas K, Mitani A, Koutsianitis D, Ntalos G, Taghiyari HR, Papadopoulos AN (2021) Thermal and mechanical properties of green insulation composites made from Cannabis and Bark residues. J Compos Sci 5:132 Nordström E, Demircan D, Fogelström L, Khabbaz F, Malmström E (2017) Green binders for wood adhesives. In: Applied adhesive bonding in science and technology. Intechopen Books, London, pp. 47–71. O’donnell A, Dweib MA, Wool RP (2004) Natural fiber composites with plant oil-based resin. Compos Sci Technol 64:1135–1145 Oh M, Ma Q, Simsek S, Bajwa D, Jiang L (2019) Comparative study of zein-and gluten-based wood adhesives containing cellulose nanofibers and crosslinking agent for improved bond strength. Int J Adhes Adhes 92:44–57 Oksman K, Bismarck A (2014) Handbook of green materials: processing technologies, properties and applications (in 4 volumes), vol 5. World Scientific, Hackensack Oktay S, Kızılcan N, Bengü B (2021) Development of bio-based cornstarch-Mimosa tannin-sugar adhesive for interior particleboard production. Ind Crop Prod 170:113689 Papadopoulos AN, Bikiaris DN, Mitropoulos AC, Kyzas GZ (2019) Nanomaterials and chemical modifications for enhanced key wood properties: a review. Nanomaterials 9(4):607 Park BD, Kim J (2008) Dynamic mechanical analysis of urea-formaldehyde resin adhesives with different formaldehyde-to-urea molar ratios. J Appl Phys 108:2045–2051 Pędzik M, Janiszewska D, Rogoziński T (2021) Alternative lignocellulosic raw materials in particleboard production: a review. Ind Crop Prod 174:114162 Pędzik M, Auriga R, Kristak L, Antov P, Rogoziński T (2022) Physical and mechanical properties of particleboard produced with addition of walnut (Juglans regia L.) wood residues. Materials 15(4):1280 Phanthong P, Reubroycharoen P, Hao X, Xu G, Abudula A, Guan G (2018) Nanocellulose: extraction and application. Carbon Resour Convers 1:32–43 Pichelin F, Nakatani M, Pizzi A, Wieland S, Despres A, Rigolet S (2006) Thick wood panels bonded industrially with formaldehyde free tannin adhesives. For Prod J 56(5):31–36 Pinkl S, Veigel S, Colson J, Gindl-Altmutter W (2017) Nanopaper properties and adhesive performance of microfibrillated cellulose from different (ligno-)cellulosic raw materials. Polymers 9:326 Pizzi A (2016) Wood products and green chemistry. Ann For Sci 73(1):185–203 Pizzi A, Papadopoulos A, Policardi F (2020) Wood composites and their polymer binders. Polymers 12:1115 Podlena M, Böhm M, Saloni D, Velarde G, Salas C (2021) Tuning the adhesive properties of soy protein wood adhesives with different coadjutant polymers, nanocellulose and lignin. Polymers 13:1972

Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview

61

Poorabdollah M, Beheshty MH, Vafayan M (2011) Kinetic modeling of nanoclay-reinforced unsaturated polyester resin. Polym Comp 32:1265–1273 Puttasukkha J, Khongtong S, Chaowana P (2015) Curing behavior and bonding performance of urea formaldehyde resin admixed with formaldehyde scavenger. Wood Res 60(4):645–654 Rangavar H, Taghiyari HR, Mehr M (2013) Effects of nanocopper on physical and mechanical properties of medium-density fiberboard. J Trop For Sci 25(2):184–192 Réh R, Krišťák Ľ, Sedliačik J, Bekhta P, Božiková M, Kunecová D, Vozárová V, Tudor EM, Antov P, Savov V (2021) Utilization of Birch Bark as an eco-friendly filler in urea-formaldehyde adhesives for plywood manufacturing. Polymers 3(4):511 Roffael E (2011) On the responsiveness of hardened UF-resins of different molar ratio towards ammonia fumigation. Eur J Wood Wood Prod 69(4):675–676 Sahoo S, Kalita H, Mohanty S, Nayak SK (2017) Synthesis and characterization of vegetable oil based polyurethane derived from low viscous bio aliphatic isocyanate: Adhesion strength to wood-wood substrate bonding. Macromol Res 25:772–778 Santos J, Pereira J, Ferra J, Magalhães FD, Martins JM, Carvalho LH (2021) New cardoon (Cynara cardunculus L.) particleboards using cardoon leaf extract and citric acid as bio-adhesive. Mater Circ Econ 3(1):1–7 Santos J, Pereira J, Escobar-Avello D, Ferreira I, Vieira C, Magalhães FD, Martins JM, Carvalho LH (2022) Grape Canes (Vitis vinifera L.) applications on packaging and particleboard industry: new bioadhesive based on grape extracts and citric acid. Polymers 14(6):1137 Saražin J, Pizzi A, Amirou S, Schmiedl D, Šernek M (2021) Organosolv lignin for non-isocyanate based polyurethanes (NIPU) as wood adhesive. J Renew Mater 9:881–907 Sarika PR, Nancarrow P, Khansaheb A, Ibrahim T (2020) Bio-based alternatives to phenol and formaldehyde for the production of resins. Polymers 12:2237 Saud AS, Maniam GP, Rahim MHA (2021) Introduction of eco-friendly adhesives: source, types, chemistry and characterization. In: Jawaid M, Khan TA, Nasir M, Asim M (eds) Eco-friendly adhesives for wood and natural fiber composites; composites science and technology. Springer, Singapore Savov V, Valchev I, Antov P (2019) Processing factors for production of eco-friendly medium density fibreboards based on lignosul-fonate adhesives. In: Proceedings of the 2nd International Congress of Biorefinery of Lignocellulosic Materials (IWBLCM 2019), Córdoba, Spain, 4–7 June 2019, pp. 165–169 Savov V, Antov P, Trichkov N (2021) Properties of high-density fiberboards bonded with urea-­ formaldehyde and phenol-formaldehyde resins. Innov Wood Ind Eng Des 2(20):17–26 Sedliačiková M, Stroková Z, Klementová J, Šatanová A, Moresová M (2020) Impacts of behavioral aspects on financial decision-making of owners of woodworking and furniture manufacturing and trading enterprises. Acta Fac Xylologiae Zvolen 62:165–176 Segovia F, Blanchet P, Essoua GGE (2021) Potential of the crude glycerol and citric acid mixture as a binder in medium-density fiberboard manufacturing. Eur J Wood Wood Prod 79(5):1141–1151 Selakjani PP, Dorieh A, Pizzi A, Shahavi MH, Hasankhah A, Shekarsaraee S, Ashouri M, Movahed SG, Abatari MN (2021) Reducing free formaldehyde emission, improvement of thickness swelling and increasing storage stability of novel medium density fiberboard by urea-­formaldehyde adhesive modified by phenol derivatives. Int J Adhes Adhes 111:102962 Seydibeyoglu MO, Oksman K (2008) Novel nanocomposites based on polyurethane and micro fibrillated cellulose. Compos Sci Technol 68:908–914 Singh SK, Ostendorf K, Euring M, Zhang K (2022) Environmentally sustainable, high-­performance lignin-derived universal adhesive. Green Chem 24:2624–2635 Singha AS, Thakur VK (2008) Effect of fibre loading on urea-formaldehyde matrix based green composites. Iran Polym J 17:861–873 So S, Rudin A (1990) Effects of resin and curing parameters on the degree of cure of resole phenolic resins and woodflour composites. J Appl Polym Sci 40:2135–2149

62

P. Antov et al.

Solt P, Konnerth J, Gindl-Altmutter W, Kantner W, Moser J, Mitter R, van Herwijnen HWG (2019) Technological performance of formaldehyde-free adhesive alternatives for particleboard industry. Int J Adhes Adhes 94:99–131 Song Y, Wang Z, Yan N et al (2016) Demethylation of wheat straw alkali lignin for application in phenol formaldehyde adhesives. Polymers (Basel) 8:209 Stewart D (2008) Lignin as a base material for materials applications: chemistry, application and economics. Ind Crops Prod 27:202–207 Sun J, Li L, Cheng H, Huang W (2018) Preparation, characterization and properties of an organic siloxane-modified cassava starch-based wood adhesive. J Adhes 94:78–293 Sutiawan J, Hermawan D, Massijaya MY, Kusumah SS, Lubis MAR, Marlina R, Purnomo D, Sulastiningsih IM (2021) Influence of different hot-pressing conditions on the performance of eco-friendly jabon plywood bonded with citric acid adhesive. Wood Mater Sci Eng. https://doi. org/10.1080/17480272.2021.1884898 Taghiyari HR, Rangavar H, Farajpour Bibalan O (2011) Nano-silver in particleboard. BioResources 6(4):4067–4075 Taghiyari HR, Mohammad-Panah B, Morrell JJ (2016) Effects of wollastonite on the properties of medium-density fiberboard (MDF) made from wood fibers and camel-thorn. Maderas Ciencia y tecnologia 18(1):157–166 Taghiyari HR, Arbabi Ghamsari F, Salimifard E (2018) Effects of adding nano-wollastonite, date palm prunings and two types of resins on the physical and mechanical properties of medium-­ density fiberboard (MDF). Bois et Forets des Tropiques 335(1):49–57 Taghiyari HR, Hosseini SB, Ghahri S, Ghofrani M, Papadopoulos AN (2020a) Formaldehyde emission in micron-sized wollastonite-treated plywood bonded with soy flour and urea-­ formaldehyde resin. Appl Sci 10:6709 Taghiyari HR, Tajvidi M, Taghiyari R, Mantanis GI, Esmailpour A, Hosseinpourpia R (2020b) Nanotechnology for wood quality improvement and protection. In: Husen A, Jawaid M (eds) Nanomaterials for agriculture and forestry applications. Elsevier, Amsterdam, pp 469–489 Taghiyari HR, Soltani A, Esmailpour A, Hassani V, Gholipour H, Papadopoulos AN (2020c) Improving thermal conductivity coefficient in oriented strand lumber (OSL) using sepiolite. Nanomaterials 10:599. https://doi.org/10.3390/nano10040599 Taghiyari HR, Esmailpour A, Majidi R, Morrell JJ, Mallaki M, Militz H, Papadopoulos AN (2020d) Potential use of wollastonite as a filler in UF resin based medium-density fiberboard (MDF). Polymers 12:1435. https://doi.org/10.3390/polym12071435 Taghiyari HR, Militz H, Antov P, Papadopoulos AN (2021) Effects of wollastonite on fire properties of particleboard made from wood and chicken feather fibers. Coatings 11(5):518 Taghiyari HR, Majidi R, Mohseni Armaki SM, Haghighatparast M (2022) Graphene as reinforcing filler in polyvinyl acetate resin. Int J Adhes Adhes 113. https://doi.org/10.1016/j. ijadhadh.2021.103075 Tajvidi M, Gardner DJ, Bousfield DW (2016) Cellulose nanomaterials as binders: laminate and particulate systems. J Renew Mater 4:365–376 Tasooji M, Tabarsa T, Khazaeian A, Wool RP (2010) Acrylated epoxidised soy oil as an alternative to urea-formaldehyde in making wheat straw particleboard. J Adhes Sci Technol 24:1717–1727 Tayeb AH, Amini E, Ghasemi S, Tajvidi M (2018) Cellulose nanomaterials—binding properties and applications: a review. Molecules 23(10):2684 Tian D, Hu J, Bao J, Chandra RP, Saddler JN, Lu C (2017) Lignin valorization: Lignin nanoparticles as high-value bio-additive for multifunctional nanocomposites. Biotechnol Biofuels Bioprod 10:192 Tisserat B, Eller F, Mankowski M (2019) Properties of composite wood panels fabricated from Eastern red cedar employing various bio-based green adhesives. BioResources 14:6666–6685 Toledano A, García A, Mondragon I, Labidi J (2010) Lignin separation and fractionation by ultrafiltration. Sep Purif Technol 71:38–43 Tomak ED, Gonultas O (2018) The wood preservative potentials of Valonia, chestnut, tara and sulphited oak tannins. J Wood Chem Technol 38:183–197 Tomani P (2010) The lignoboost process. Cellul Chem Technol 44:53–58

Potential of Nanomaterials in Bio-Based Wood Adhesives: An Overview

63

Trache D, Hussin MH, Brosse N (2020) Editorial: recent trends in preparation, characterization and applications of nanocellulose. Front Chem 8:594379 Tudor EM, Kristak L, Barbu MC, Gergeľ T, Němec M, Kain G, Réh R (2021) Acoustic properties of larch bark panels. Forests 12(7):887 Umemura K, Inoue A, Kawai S (2003) Development of new natural polymer-based wood adhesive I: dry bond strength and water resistance of Konjac glucomannan, chitosan and their composites. J Wood Sci 49:221–226 US Consumer Product Safety Commission (2013) An update on formaldehyde (Publication 725). Bethesda, US Consumer Product Safety Commission Vahabi H, Brosse N, Latif NHA et al (2021) Nanolignin in materials science and technology— does flame retardancy matter? 1st edn. Elsevier Ltd Valenzuela J, von Leyser E, Pizzi A, Westermeyer C, Gorrini B (2012) Industrial production of pine tannin-bonded particleboard and MDF. Eur J Wood Prod 70:735–740 Veigel S, Rathke J, Weigl M, Gindl-Altmutter W (2012) Particle board and oriented strand board prepared with nanocellulose-reinforced adhesive. J Nanomater 2012:158503 Vineeth SK, Gadhave RV, Gadekar PT (2019a) Nanocellulose applications in wood adhesives review. Open J Polym Chem 9:63–75 Vineeth SK, Gadhave RV, Gadekar PT (2019b) Chemical modification of nanocellulose in wood adhesive: review. Open J Polym Chem 9:86–99 Vishnuvarthanan M, Shahidah A, Fathima M, Gobika NR, Priyadharshini B, Rasika B (2021) Effect of alumina silicate (MMT K10) nanoclay on adhesion and barrier properties of cornstarch-­based bioadhesive. Silicon 13:4315–4322 Wang Z, Gu Z, Hong Y, Cheng L, Li Z (2011) Bonding strength and water resistance of starch-­ based wood adhesive improved by silica nanoparticles. Carbohydr Polym 86:72–76 Wedaïna AG, Pizzi A, Nzie W, Dawne R, Konai N, Amirou S, Segovia C, Kueny R (2021) Performance of unidirectional biocomposite developed with Piptadeniastrum Africanum tannin resin and Urena Lobata fibers as reinforcement. J Renew Mater 9:477–493 Wibowo ES, Lubis MAR, Park BD, Kim JS, Causin V (2020) Converting crystalline thermosetting urea-formaldehyde resins to amorphous polymer using modified nanoclay. J Ind Eng Chem 87:78–89 Xi X, Wu Z, Pizzi A, Gerardin C, Lei H, Du G (2020) Furfuryl alcohol-aldehyde plywood adhesive resins. J Adhes 96(9):814–838 Yang W, Rallini M, Natali M et al (2019) Preparation and properties of adhesives based on phenolic resin containing lignin micro and nanoparticles: a comparative study. Mater Des 161:55–63 Yildirim M, Candan Z (2021) Performance properties of particleboard panels modified with nanocellulose/boric acid. BioResources 16:1875–1890 Younesi-Kordkheili H, Pizzi A (2022) Preparation and properties of a modified corn flour-­ lignin-­glyoxal as a green wood adhesive. Int Wood Prod J. https://doi.org/10.1080/2042644 5.2022.2048338 Yue X, Huang L, Huang L, Luo X (2021) A sustainable strategy for medium-density fiberboards preparation from waste hybrid pennisetum straws. Waste Biomass Valor 12(9):5161–5173 Zhang S, Xia C (2016) Soy protein isolate-based films reinforced by surface modified cellulose nanocrystal. Ind Crop Prod 80:207–213 Zhang B, Zhang F, Wu L, Gao Z, Zhang L (2020) Assessment of soybean protein-based adhesive formulations, prepared by different liquefaction technologies for particleboard applications. Wood Sci Technol 55:33–48 Zhang K, Liu Y, Guo Z, Wang J, Liu Y, Zhao J, Huo P (2022) Co-modification of corn straw lignin and its enhancement on glue-free fiberboard based on freezing activated wood fibers. Ind Crop Prod 177:114452 Zhou X, Du G (2019) Applications of tannin resin adhesives in the wood industry. In: Tannins structural properties, biological properties and current knowledge. IntechOpen, London

Nanomaterials to Improve Fire Properties in Wood and Wood-Based Composite Panels Jakub Kawalerczyk, Joanna Walkiewicz, Dorota Dziurka, and Radosław Mirski

Contents 1  Introduction 2  Mineral Nanoparticles 3  Nano-Oxides 4  Carbon-Based Nanoparticles 5  Health Risks and Toxicity 6  Summary References

 65  69  75  79  81  84  85

1 Introduction Nanotechnology is a branch of science that includes the production and applications of nanomaterials (NMs) and literally any operations on the nanoscale performed in order to achieve control over a structure of nanomaterials and to develop the effective methods of their production and use. The criterion allowing to define and identify the NMs is the size of their particles – at least one of their dimensions must not exceed 100 nm (Poole Jr and Owens 2003; Kawalerczyk et al. 2021a). It is a dynamically developing field combining the achievements of other material engineering, chemistry, physics, biology, etc. Although the nanotechnology is associated as a relatively new object of scientific interests, the nature presents examples of nanomaterials

J. Kawalerczyk (*) · J. Walkiewicz · D. Dziurka · R. Mirski Department of Mechanical Wood Technology, Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, Poznań, Poland e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 H. R. Taghiyari et al. (eds.), Emerging Nanomaterials, https://doi.org/10.1007/978-3-031-17378-3_3

65

66

J. Kawalerczyk et al.

synthesized through the natural processes (Uddin et al. 2013). Furthermore, with the development of research tools and methods for NMs, the synthesis of new, unprecedented materials having unique properties has also become the subject of many studies. They are expected to find various applications in many areas that people encounter in daily life (Lidén 2011; Bhushan 2017). Their wide use is primarily due to a wide range of particularly favorable properties. Nanomaterials have excellent physicochemical and mechanical properties resulting from the volume, surface, and quantum effect of nanoparticles (Wu et al. 2020). Their features are strongly dependent on the characteristics of nanoparticles such as their size, surface area, solubility, shape, crystal structure, and agglomeration state (Gatoo et  al. 2014). Consequently, there are many potential ways of NM applications, for example, medicine, chemical industry, electronics, military, environmental sciences, and packing materials (Bradley et al. 2011; Ghasemzadeh et al. 2014; Prakash Sharma et al. 2018). Moreover, the emerging concept of nanotechnology incorporation into the field of fire protection also seems to have a great potential (Olawoyin 2018; Rabajczyk et al. 2021). The example of material of a natural origin that requires protection against fire is wood. Since time immemorial, it has been used by human in everyday life as fuel and construction material. Due to the porous structure and the system of submicroscopic capillaries, it is characterized by the high mechanical strength and low specific weight. Moreover, wood is also a thermal-insulating, sound-absorbing material, which can be easily processed, joined without fasteners and, at the same time, it is distinguished by a high aesthetics of appearance. Over the years, wood still retains the position of a raw material with a wide range of applications as evidenced by the constant increase in consumption and prices (Wieruszewski et al. 2015; Mirski et al. 2020). It is used on a large scale in many industries such as construction, energetics, production of industrial machinery, floors, and furniture. However, its high hygroscopicity, low dimensional stability, defects related to the morphological structure of trees and susceptibility to degradation by fungi or fire can be listed among the major disadvantages of wood (Xue et al. 2018). Combustibility of wood results from the large number of oxygen atoms in the composition of wood main constituents (Grześkowiak et  al. 2016; Kawalerczyk et al. 2019). The flammable nature of timber can be a limiting factor for its application, for example, in building construction. The unprotected wooden elements can contribute to the fire growth and the enhancement of toxicity resulting from the increased production of carbon monoxide, especially in the smoldering phase of a fire (Xu et al. 2015; Thomas et al. 2021). In general, the combustion of wood is a complex process that differs significantly from the combustion of gases, liquids, and solids, which do not carbonize during the incineration. It is preceded by its thermal decomposition and the formation of products having different physical states. The arising volatile products burn in a homogeneous mixture with an air, while the charcoal resulting from decomposition is burned in a heterogeneous system. Thus, it can be concluded that this type of chemical transformation means that the combustion of wood is a complex and multi-stage process (Pofit-Szczepańska et al. 2014). In order to protect the wooden elements, the fire retardants (FRs) are commonly applied. They can be defined as the substances added to combustible materials to improve their resistance to ignition (Mazela et al. 2020). According to Camino and Costa (1988), the ideal fire retardant should be characterized by the following features: thermal stability, low toxicity, compatibility with the protected material, and no

Nanomaterials to Improve Fire Properties in Wood and Wood-Based Composite Panels

67

change in the physicochemical properties of the material. The idea of improving fire resistance of wood itself is definitely not a new invention. Three thousand years ago, Egyptians observed that the grasses used as the roof cover, which have been previously soaked in the sea water, got more resistant to ignition due to the salts crystallized on their surface during drying. The development of technology in next centuries brought the new substances such as alum, clay, water glass, lime slurry, and painting chalk, which were included in the formulations of fire retardants. In the second half of last century, a very rapid development of the chemical agents applied to increase wood fire resistance began (Cyrankowski et al. 2013). However, despite their relatively high effectiveness, they usually contain nitrogen, boron, or phosphorous compounds, which adversely affect human and animal health due to their toxicity (Wang et al. 2010a; Yu et al. 2016). Moreover, the treatment with this kind of chemicals can also negatively affect properties of wood in such ways as increased hygroscopicity, reduced mechanical strength, changes in dimensional stability, corrosion with metal fasteners, increased abrasiveness, etc. (LeVan and Winandy 1990; Taghiyari 2012). Consequently, it is important to seek the new methods for fire proofing wooden elements using innovative systems based on, for example, the nanoparticles or bioderived substrates (Hernandez et  al. 2022). The use of nanotechnology solutions seems to be particularly reasonable choice due to the fact that there are many studies providing the information that nanomodification can lead to the improvement in the properties of wood and the increase in the effectiveness of its protection (Beecher 2007; Evans et al. 2008; Berglund and Burgert 2018; Teng et al. 2018). Along with the development of technology, many types of wood-based materials have gained a considerable popularity. These are the composite boards made of wood pieces having various forms, bonded together with the synthetic or natural binding agents. In comparison with the solid wood, wood-based materials are characterized by many advantageous features such as much greater homogeneity, isotropy, and reproducibility (Treusch et al. 2004; Sedliacik et al. 2010). Consequently, the demand for this type of materials is also constantly growing. The increasing tendencies in export, import, and production quantity can be observed since 1961, and they are expected to continue to grow (Gonçalves et  al. 2018; Bekhta et  al. 2020). Both wood and wood-based materials are so successful on the market that according to Fridley (2002) they are equally important as steel of concrete from an economic standpoint. Since the beginning, wood-based materials have been successfully introduced into the engineering and construction marketplace as the products used for the beams, columns, frames, flooring, and the structural panels manufacturing. However, these kinds of applications require the fulfillment of a number of technical criteria, which are stipulated by many ordinances. The example of such criterion can be the fire safety of the entire construction. According to Harada et al. (2006) when wood-based panels are used as the construction material, the following qualities are desired: (i) the structure does not deform, break down, or melt, (ii) the unexposed side temperature does not exceed the burning temperature of flammable material, and (iii) the structure does not crack or become otherwise damaged due to the fire outside the building. In order to achieve these qualities, the fire retardant treatments are required. Three main approaches have been identified and commonly studied for introducing fire retardants into the production of wood-­ based panels (Fig. 1) (Grexa et al. 1999; Thomas et al. 2021).

68

J. Kawalerczyk et al.

Fig. 1  The methods of applying fire retardants in wood-based materials

The ignition and combustion of wood are initially the surface processes; therefore, the application of appropriate coatings can improve fire resistance of wood in the event of impact of both the low-energy heat sources and high-energy heat fluxes generated by the fire (Zhang et al. 2016a; Seo et al. 2017). The advantages of coating systems certainly include the easy application and the fact that they are relatively economically beneficial. One of the biggest disadvantage, however, is the fact that the coatings can wear and leach from the wood structure, which means that they often need a renewed application with time. Studies conducted on biocides indicate that this could be prevented or limited by the use of solutions associated with nanotechnology (Heiden et al. 2005; Salma et al. 2010). It is especially important because every damage and decomposition of the applied coating systems reduce the effectiveness of the flame retardant (Bahrani et al. 2018; Schirp and Schwarz 2021). Contrary to coatings, impregnation of wood (fibers, chips, flour, and veneer) and the introduction of FR into the adhesive or polymer enable the protection of the wood-­based material along the entire cross-section. Conventional fire retardants are typically used for both of these methods, similarly as is the case of solid wood. However, the inorganic substances usually adversely affect bonding quality of manufactured panels due to the incompatibility between binding agent and FR, mechanical interference by the salts, reduction in both viscosity of resin, and the number of hydroxyl groups available for hydrogen bonding (Ayrilmis et al. 2009). Therefore, there is a necessity to provide the new solutions, which will reduce the negative effect of the protection, for example, with the use of nanosized particles. This could be particularly beneficial due to the fact that it was previously proven that nanoparticles can also contribute to lowering adhesive consumption (Dukarska and Czarnecki 2016; Kawalerczyk et  al. 2021b), increasing mechanical strength (Muñoz et al. 2018; Kawalerczyk et al. 2020), reducing formaldehyde emissions (Yamanaka et al. 2017; de Cademartori et al. 2019), and limiting biodegradation (Nur Izreen Farah et al. 2021; Pour et al. 2021) of wood-based composites.

Nanomaterials to Improve Fire Properties in Wood and Wood-Based Composite Panels

69

With technical progress, wood and wood products do not lose their importance, on the contrary, the development of new protection systems, such as those based on the nanoparticles, could expand the directions of their application. Therefore, the aim of this paper is to present the current knowledge on the innovative fire protection systems, which were brought up by nanotechnology.

2 Mineral Nanoparticles An interesting example of nanoparticles which currently are the subject of research in many fields of scientific interest is mineral nanoparticles (MNs), namely nanoclays. They can be distributed through the nature in atmosphere, soils, groundwater, surface waters, etc., or synthesized. Their resources are very large; according to Guo et al. (2018), the advantages of MN include the availability, the relatively low cost, and environmental impact. However, it is difficult to assess precisely the specific values since the oceans may be the principal reservoir for them (Hochella Jr et al. 2008). Properties of nanoclays, for example, their stoichiometry, surface structure, degree of order, and strain, vary depending on the size and formation conditions (Waychunas and Zhang 2008). They are built of the layered structural units forming the complex clay crystallites by stacking these adjacent layers to each other with der Waals forces (Guo et al. 2018). The arrangement of individual layers plays a crucial role in distinguishing and defining these clay materials (Nazir et al. 2016). Various types of MN have many interesting applications such as the use in fire protection systems. Wood mineralization performed by adding the synthetic or natural nanominerals into the wood structure may have a great potential as the environmentally friendly, non-toxic fire protection (Fu et al. 2017; Zhang et al. 2021). Montmorillonite (MMT) is a nanoclay composed of alumina octahedral sheet between the two silica tetrahedral sheets (Wu et al. 2015; Ahmed et al. 2018; Zhang et  al. 2021). This kind of aluminosilicates, characterized by the low dimensions (1–5 nm) and diameter (100–500 nm) impart platelets with a high aspect ratio. Due to that, its addition causes the improvement in stiffness and strength of the composites (Okada and Usuki 2006; Alias et al. 2021). Moreover, besides the reinforcing effect on the mechanical properties of both synthetic and natural polymer nanocomposites, it was also found to be effective in improving their fire resistance. The addition of MMT, even in a small concentrations (less than 5% in most cases), to the polymer matrix, can significantly improve the thermal stability, flame-resistant, and flame-barrier properties (Bertini et  al. 2006; Lakshmi et  al. 2008; Huang et  al. 2010). The improvement in physical properties results from the interfacial intercommunication between the silicate layers and polymer matrix. Moreover, it was observed that the presence of MMT can reduce the heat release and produce char when compared with the neat polymer (Chigwada et al. 2008; Ahmed et al. 2018). Wood plastic composites (WPCs) are increasingly finding new industrial applications. These composites are made of wood fibers, wood dust, or wood flour embedded in thermoplastics matrix. Besides contributing toward the positive effect on the tensile and flexural strength of WPC, the addition of MMT also improves their flame-retarding properties (Xue and Zhao 2008; Nemati et al. 2013; Fu et al. 2017).

70

J. Kawalerczyk et al.

Studies also have shown that the modification of MMT with 2-acryloyloxy ethyl trimethylammonium chloride (ATAC), cetyltrimethylammonium bromide (CTAB), and their mixture prior to blending with the polymer and wood can contribute to even greater improvement in fire retardancy of WPC. Both the CTAB and ATAC introduction expand the silicate layers more when compared with non-modified MMT, which results in a delayed burning of WPC due to better barrier properties to the oxygen and the heat (Deka and Maji 2011; Hazarika and Maji 2013). Furthermore, besides the PVC, PP, and PE, which are commonly used for WPC production, the nano-MMT was also studied as an additive for isocyanates and formaldehyde-containing adhesives such as phenol-formaldehyde (PF) and urea-­ formaldehyde (UF) resins. Studies have shown that the introduction of nanosized MMT positively influences the thermosetting performance of UF resin and the physicomechanical properties of manufactured plywood and particleboard panels (Lei et al. 2008; Doosthoseini and Zarea-Hosseinabadi 2010; Hosseyni et al. 2014; Muñoz et al. 2018). However, none of these studies investigated the effect of adhesive modification on thermal properties and flammability of the boards. Promising results in terms of poplar wood fire protection were obtained by hybrid organic-inorganic modification. The wood that had been previously delignified in order to increase its nano-porosity was impregnated with mixture of furfuryl alcohol (FA) and MMT as a catalyst. Studies have shown that wood modified this way is characterized by the great fire retardancy due to the polymerization of FA, reduction in the amount of flammable gases, and impediment in the diffusion of heat (Zhang et  al. 2021). It could be particularly beneficial since the incorporation of MMT and organo-modified MMT can contribute also to the increase in dimensional stability, compression strength, and surface hardness of wood (Wang et al. 2014). Montmorillonite has been also investigated as the additive in the creation of coatings for the fire protection of wood and wood-based materials. It can be applied as the inorganic synergist to prepare the water-based intumescent flame retardant (IFR) ornamental coating for plywood. The outcomes clearly show that the MMT-enriched IFR coating (7 wt%) has significantly better fire behavior due to the less heat release and prolonged combustion (Hu et al. 2020, 2022). Moreover, it turned out that the incorporation of montmorillonite polyphosphate (OPEA) has also favorable effect on char index, mass loss, and flame spread rating of the coating, which can be attributed the increase in the intumescent factor (Yan et al. 2018). In addition, according to authors, it can be associated also with the creation of the more thermally stable, compact char layer formed during the combustion. Formulation of waterborne fire-­ retardant coating based on chitosan, melamine-formaldehyde resin, ammonium polyphosphate, waterborne epoxy resin, and organo-modified MMT was found to cause the formation of char layer exhibiting the superior isolation effect. Consequently, it significantly improved the flammability of pine wood (Li et  al. 2021). According to Xu et al. (2020b), the inclusion of MMT in the coating systems has synergistic effect on wood fire protection. Another example of extensively studied nanoclay is sepiolite (SEP). It is a hydrated magnesium silicate with half unite-cell formula Mg4Si6O15(OH)2·6H2O. Nanoscale sepiolite is a mineral nanoparticle characterized

Nanomaterials to Improve Fire Properties in Wood and Wood-Based Composite Panels

71

by needle-like morphology, composed of the layer of magnesium ions with octahedral coordination and two layers of silica in tetrahedron (Olivato et al. 2017; Khan et al. 2022). In comparison with platelet-like MMT structures, sepiolite has smaller interface surface, which makes the nanoparticles more easily dispersible within the matrix (Bilotti et al. 2008). Furthermore, according to Liu et al. (2012), the addition of nano-SEP may prevent the flocculation and reduce the particle agglomeration in the polymer structure. Similarly as in case of different phyllosilicates, it has a nanometer tunnel structure (with a cross-sections of 1 × 0.4 nm2), which enhances the specific surface area up to 200–300 m2/g (Zheng and Zheng 2006; Yu et al. 2011; Suárez and García-Romero 2012; Khan et  al. 2022). Because of that, sepiolite nanoparticles are widely used as a filler in various types of polymeric materials. The addition of SEP positively affects properties of bio-based and synthetic nanocomposites by causing the increase in their thermomechanical properties (Chivrac et al. 2010; Olivato et al. 2015; Mohd Zaini et al. 2017; Raji et al. 2018). Moreover, the properties of hybrid SEP-filled WPCs have also been the subject of a few scientific studies (Özdemir et al. 2018; Kaymakci 2020). The obtained results show that the SEP-reinforced WPCs are characterized by a reduced swelling and water absorption. The possible explanation for this phenomenon can be either: (i) hydrophilic nature of clay surface that tends to immobilize some moisture, (ii) favorable barrier properties of nanoclays, or (iii) ability of nanoclay to act like the nucleating agent (Alexandre and Dubois 2000; Bharadwaj et al. 2002; Rana et al. 2005; Ghasemi and Kord 2009). Furthermore, the addition of SEP also increases mechanical properties of produced WPCs due to the extraordinary ability of clays to carry the tensile load and the great stiffness of nanosized SEP particles themselves. In addition, the improvement in thermal stability and thermal conductivity can be observed for these composites, which may suggest the positive effect also on their fire resistance. Study carried out on PLA-hemp fiber-SEP composites shows that the load with nano-SEP has a catalytic effect on the pyrolysis of PLA due to acting like a heat barrier and enhancing the char formation after the thermal decomposition (Hapuarachchi and Peijs 2010). The attempts to apply nanosized sepiolite particles as a modifier for UF resin have also been made (Papadopoulos 2020). However, while a considerable number of publications regarding the reinforcement of polymers can be found, the literature on sepiolite-reinforced adhesives applied for wood bonding is rather scarce. The addition of SEP nanoparticles to the UF resin causes a significant improvement in plywood wet shear strength by 31% when compared with panels bonded with the non-modified adhesive. Moreover, the incorporation of SEP also contributes to the decrease in formaldehyde emission from resultant plywood by up to 44%, which is a very promising result (Li et al. 2015). Similar modification of the UF adhesive was performed by Taghiyari et al. (2020b). The study concerned the production of oriented strand lumber (OSL) panels and investigated the effect of nano-modification on their thermal conductivity and hardness. The increase in heat transfer during the hot pressing process is crucial due to possible economic benefits (Mirski et al. 2011) and more complete curing of resin resulting in the improvement of mechanical properties (Taghiyari and Farajpour Bibalan 2013). The outcomes show the

72

J. Kawalerczyk et al.

significant increase in thermal conductivity of panels containing SEP-modified adhesive. Moreover, the addition of SEP as the filler has a positive effect on hardness of OSL boards, which probably can be attributed to the enhancement in resin curing (Taghiyari et  al. 2020b). The increased thermal conductivity is of great importance in terms of fire resistance since it prevents the fast accumulation of heat in one spot, which ultimately prolongs the time needed for wood to burn (Taghiyari et al. 2020c). Similarly to MMT, nano-sepiolite is also used in the development of new solutions in the field of fire-retardant coatings. The SEP-modified paint applied on the surface of both heat-treated and unheated fir wood was found to effectively improve the fire properties such as mass loss, burnt area, and the time of ignition, glowing, back-darkening, and back-holing (Taghiyari et al. 2021b). The particularly positive effect can be attributed to the mineral nature of nanosized SEP itself associated with the low chemical reactivity, great barrier properties, and the particularly high thermal conductivity coefficient, which results in hindering the accumulation of heat (Taghiyari et al. 2021b). Promising results were obtained also in terms of transparent fire-retardant coatings. The formulation consisting of melamine-formaldehyde resin and SEP modified with polyphosphate ester (PPB) can be used to develop transparent surface protection, which creates more compact and intumescent char layer during the combustion (Xu et  al. 2020a). Moreover, according to Xu et  al. (2020b) the addition of SEP has a more notable impact on coatings fire behavior when compared with MMT. Nano-wollastonite (NW) has also attracted the attention of scientists in recent years. It is a calcium silicate (CaSiO3) mineral exploited for its chemistry as a source of CaO and SiO2 (Tichi et al. 2019). NW possesses many favorable features such as relatively high hardness (Mohs hardness of 4.8), specific gravity of 2.9, alkaline pH of 9.8, high aspect ratio, favorable thermal stability, low thermal expansion coefficient, and low water absorption (Milewski and Katz 1987; Luyt et al. 2009; Tichi et al. 2016). Because of them, it is widely used as a functional filler for polymers, which is able to improve the properties of thermoplastic matrix in the aspect of mechanical properties, water uptake, rheological behavior, scratch resistance, etc. (Shenoy and Saini 1986; Chu et  al. 2000; Ding et  al. 2019; Chan et  al. 2020). Moreover, wollastonite nanoparticles are also applied as the additive providing the enhancement in flame retardancy of commonly investigated thermoplastics, for example, PP, PE, PA, PVC, and PS (Wong et al. 2021). Therefore, NW has a great potential to replace the other conventional fillers such as talc or glass fibers in the development of innovative, high-performance materials. These certainly include the wollastonite-reinforced WPCs, which are characterized by the decreased water absorption, the increased tensile strength, hardness, and biological resistance against fungi when compared with the non-modified composites (Huuhilo et al. 2010a, b; Bari et al. 2015; Rangavar et al. 2016). Furthermore, the incorporation of NW into the WPC contributes also to the improvement in their flammable properties due to the increase in thermal conductivity, extension of ignition time, and the reduction in both mass loss and the heat release rate (Nikolaeva and Kärki 2013).

Nanomaterials to Improve Fire Properties in Wood and Wood-Based Composite Panels

73

In comparison with MMT and SEP, nano-wollastonite has been the subject of extensive research in the application as the reinforcing agent for wood-based materials. The presence of wollastonite nanoparticles significantly improves the properties of medium density fiberboard (MDF) manufactured with the use of only wood fibers and wood mixed with chicken feathers or camel thorn. NW has a positive effect both as an additive applied on the surface and internally into the mat. The introduction of NW improves the mechanical and physical properties of the resultant panels, decreases their biodegradation, and limits the permeability of gases or liquids. It is attributed mostly to the enhanced resin curing in the core layer of the fibrous mat resulting from the increased thermal conductivity. Wollastonite nanoparticles are able to accelerate the heat transfer in a similar way as the nano-metals (Taghiyari et al. 2019). Moreover, at the same time, the improvement can be caused by the strong adsorption of NW on the cellulose surface. In the end, both of these increase the overall integrity of the boards. Nano-modification contributes also to the significant improvement in fire resistance of manufactured MDF panels. The positive changes in the time of ignition and glowing, reduced dimensions of burnt area, and lowered mass loss can be observed due to the less heat build-up in one spot, increased integrity of the panels, and creation of less combustible surface limiting the fire penetration to the inner layers of the MDF (Taghiyari et al. 2013b, c; Taghiyari and Nouri 2015; Taghiyari et al. 2016a, b; Taghiyari and Sarvari Samadi 2016; Esmailpour et al. 2020b, 2021). Moreover, mixing NW with wood particles can also contribute to the improvement in the particleboard panel characteristics (Taghiyari et al. 2013a). Besides that, wollastonite can be also successfully applied as a filler for UF adhesive, which positively influences properties of plywood (Taghiyari et al. 2020a), particleboard (Yadav 2021), and OSL board (Hassani et al. 2019). According to Taghiyari et al. (2020b), the reinforcing effect of nanoparticles introduced to the resin results from (i) bonding between the NW and the hydroxyl groups of cellulose and (ii) accelerated curing of the adhesive. Nano-wollastonite can also be used to protect both non-modified and heat-treated solid wood species, for example, poplar, beech, and fir. Due to the mineral nature of NW, it acts like a physical shield against fire penetrating into the wood structure. Moreover, the increased thermal conductivity also prevents the accumulation of heat and consequently improves the fire properties of wood. Studies have shown that the optimum concentration of NW in the impregnating suspension is 10%. Moreover, the treatment improves wood resistance against decaying fungi and does not cause any significant deterioration in the mechanical properties (Haghighi et al. 2013a, b; Karimi et al. 2013; Poshtiri et al. 2014; Soltani et al. 2016; Taghiyari et al. 2017a). Furthermore, the combine treatment of wood with NW and styrene shows promising results in terms of fire resistance, dimensional stability, and mechanical properties of poplar wood (Izadyar et al. 2019, 2020). NW can be also applied as the multifunctional additive for acrylic coatings (Khojasteh Khosro and Taghipour Javy 2018). The outcomes have shown that the introduction of NW in the amount of 2.5% has a significantly positive effect on the time of ignition of spruce and sycamore wood and the adhesion strength. Fire retarding properties of particleboard modified with NW were also determined (Esmailpour

74

J. Kawalerczyk et al.

et al. 2018). It was concluded that spraying the NW-reinforced water-based paint on wood surface can substantially influence its flammable properties. Moreover, it was also found that this kind of surface treatment is more effective when compared with the UF resin modification with NW. In summary, the mineral nanoparticles have a great potential in improving the fire resistance of wood and wood-based composites due to their availability; mineral nature, which guarantees very good barrier properties; the advantageous heat-­ transferring properties; and non-toxicity (Table 1). Table 1  The effect of mineral nanoparticles on the fire resistance of wood and wood-based composites Type of nanoparticles Nano-­ montmorillonite (MMT)

Nano-sepiolite (SEP)

Effect on fire resistance Improved fire resistance of WPC

Way of introduction Polymer reinforcement

Improved fire properties of wood

Impregnation together with furfuryl alcohol

Fire-resistant intumescent coatings for wood and wood-based composites Improved fire resistance of WPC

Surface treatment

Improved fire resistance of OSL

Urea-formaldehyde adhesive reinforcement

Fire-resistant paints Transparent coatings Nano-wollastonite Improved fire resistance of (NW) WPC

Polymer reinforcement

Surface treatment Polymer reinforcement

Additional positive effects Mechanical properties Physical properties Dimensional stability Hardness Compression strength Thermal stability Intumescent factor Thickness swelling and water absorption Mechanical properties Bonding quality and formaldehyde emission of plywood Hardness of OSL No data available

Water absorption Mechanical properties Hardness Biological resistance Improved fire resistance of Surface treatment or Mechanical MDF, MDF from wood fibers mixing internally properties and chicken feathers, MDF with the fibers Physical properties from wood fibers camel thorn Biological resistance Permeability of gases and liquids Resin curing Improved fire resistance of Impregnating Biological resistance wood suspension Fire resistant water-based Surface treatment No data available paints and acrylic coatings

Nanomaterials to Improve Fire Properties in Wood and Wood-Based Composite Panels

75

3 Nano-Oxides Due to their unique properties, nano-oxides (N-O) are among the most intensively studied materials in recent years (Sharma et al. 2020). Due to the range of advantageous features, they can be successfully used as fillers for providing a multifunctional polymer, ceramic, and carbon nanocomposites (Zhao et  al. 2020). N-O demonstrate the unique physical and chemical properties when compared with their bulk counterparts. Their performance can be strongly dependent upon the particle morphology and size. However, despite the enormous progress, which can be observed in recent years in terms of synthesis and finding new applications for N-O, more research is required to better understand their unusual properties and to develop new areas in which they can find the innovative possibilities for application. Nano-SiO2 is a white powder composed of amorphous silica with a high chemical purity. It has the advantages of strong surface adsorption, large specific surface area, great surface energy, and good dispersion (Zhang et  al. 2017; Zhuang and Chen 2019). For this reason, silica nanoparticles are widely used to improve the properties of polymeric materials, especially due to the uniform dispersion and good interaction with the polymer matrix. The reinforcing effect of nano-SiO2 can be also observed in case of WPCs. It leads to the manufacturing of wood-containing composites characterized by the improved weathering performance, mechanical and physical properties, and thermal stability (Mishra and Luyt 2008; Kumar et al. 2011; Hao et al. 2019; Liu et al. 2019; Wang et al. 2021). Moreover, the incorporation of nano-silica and its subsequent presence in the wood cell wall and cell lumens leads to the enhancement in the flammable properties of composites. It results in the production of smaller flame and more char mainly due to acting like a thermal barrier to the oxygen and heat, which consequently delays the burning capacity of composites (Camino et al. 2005; Shi et al. 2007; Devi and Maji 2012). Attention has also recently turned to the manufacturing of wood-based materials with the use of formaldehyde-containing adhesives reinforced with nano-SiO2. The introduction of nano-silica improves the thermosetting performance of the resins (Dukarska and Bartkowiak 2016). Moreover, it allows to produce panels such as particleboards, OSB boards, plywood with the increased mechanical strength, thermal conductivity, reduced water absorption, limited biological degradation caused by Aspergillus niger and decreased adhesive consumption (Roumeli et  al. 2012; Salari et  al. 2013; Dukarska and Czarnecki 2016; Dukarska et  al. 2017). On the example of particleboards, it was observed that this type of modification also leads to the improvement in the flammable properties of wood-based panels. The application of nano-SiO2-modified UF resin results in the extension of ignition time and reduction of mass loss during the particleboard combustion. This phenomenon can be explained through the exceptional barrier properties and increased thermal capacity of nano-silica. It means that these nanoparticles can absorb part of the heat and prevent the penetration of high temperature into the core layer of particleboard (Dukarska 2019). The aqueous dispersion of nano-SiO2 can be also applied as the fire retardant for veneers intended to the bonding process. Studies have shown that the immersion of pine veneers in a 3 wt% nano-SiO2 dispersion effectively improves

76

J. Kawalerczyk et al.

thermal properties and flammability of the wood sheets, which indicate the possible flame retarding effect on the veneer-based products such as laminated veneer lumber (LVL) or plywood (Bueno et al. 2014). Nano-silica has also been investigated as the preservative for solid wood. The impregnation seems to be successful in terms of improving beech and pine wood hydrophobic properties, and it leads to the reduction of shrinking, swelling, water uptake, and equilibrium moisture content (Bak et al. 2019). However, the outcomes presented by Karaman et al. (2019) indicate that modification of wood with nano-­ silica solution can result in the decrease of bending strength (by approx. 3–5%) and modulus of elasticity (by approx. 0.6–9%). In response, an interesting approach to incorporate the SiO2 nanoparticles into the wood impregnation process by combining them with, for example, furfuryl alcohol (Dong et al. 2015), paraffin (Liu et al. 2020), or mono-ethylene glycol (Rahayu et al. 2020), has been investigated. The presence of nano-silica can improve effectiveness of these substances and reduce the negative impact on wood properties. Furthermore, the treatment of wood with FA or paraffine mixed with nano-SiO2 positively influences its thermal stability. In addition, using the combination of FA and silica nanoparticles significantly decrease smoke production rate, heat release rate, mass loss rate, specific extinction areas, and CO and CO2 emissions. Thus, it has a particularly positive effect on the fire resistance of poplar wood (Dong et al. 2015). Nano-metals and nano-metal oxides are listed among the most used and studied nanoparticles in general. They are characterized by many particularly positive features such as high surface to volume ratio, good stability, ease of preparation, and homogeneous particles size distribution that make them widely applied to improve the physical and mechanical properties of various materials (Lewandowska et al. 2010; Huang et al. 2015). Moreover, the use of nano-metal oxides can provide the next generation of products for wood protection against bacteria, fungi, and fire by either using them alone or in amalgamation with the already existing solutions. Some of the nano-metal oxides such as TiO2 and ZnO distributed within the polymer matrix can improve fire retardancy of the resultant WPC due to their unique heat-transferring abilities (Devi and Maji 2013; Kiaei et al. 2017). Moreover, their addition can also contribute to the increased mechanical strength and biological resistance against fungi of wood-containing plastic composites (Farahani and Banikarim 2013). The high thermal conductivity coefficient of nano-metal oxides is also favorable in terms of wood-based material production. The addition of TiO2, ZnO, and CuO nanoparticles or nano-silver causes the accelerated heat transfer resulting in the improved integrity of the board due to the more complete resin curing. Moreover, the high thermal conductivity of nano-metal oxides can cause a significant improvement in the fire resistance, similarly as in case of mineral nanoparticles and nano-­ silica. In addition, the incorporation of these nano-modifiers results in the increased mechanical, physical, thermal properties of particleboards, MDF boards, and plywood panels and prevents the attack of biological deteriorating agents (Ghofrani et al. 2015; Marzbani et al. 2015; Norani et al. 2017; Ozcifci et al. 2018; da Silva et al. 2019; Kizilkaya et al. 2020; Pour et al. 2021).

Nanomaterials to Improve Fire Properties in Wood and Wood-Based Composite Panels

77

The nano-metals and nano-metal oxide suspensions were also investigated in terms of solid wood protection. The immersion of pine veneers in the aqueous dispersion of nano-TiO2 slightly improves fire protection of veneers intended for plywood manufacturing. However, the obtained effect is not as notable as in case of nano-silica application (Bueno et  al. 2014). Studies also have shown that the impregnation of pine wood with ZnO nanoparticles can have a positive effect on its fire protection. The nano-ZnO act as thermo-protective barrier, which prevents the spread of flames and, thus, the impregnation results in the improvement in both the ignition time and the combustion time (Favarim and Leite 2018). Besides pine wood, the nano-ZnO mixed with sodium silicate can be also applied as the fire protection system for the oak wood. The added nanoparticles results in faster release of non-combustible gases and as a consequence, it slows down the combustion process. When comparing the effect of SiO2, ZnO, and TiO2, ZnO has the greatest influence on wood fire proofing (Kačíková et  al. 2021). Moreover, these nano-metal oxides can also contribute to the improved fungi and termite resistance, can reduce leaching and water absorption during weathering process, and can increase UV protection and gas permeability of wood (Clausen 2012; Ghorbani et al. 2012; Marzbani and Mohammadnia-afrouzi 2014; Terzi et al. 2016). The fire retardancy of wood can be also improved by the addition of nano-silver suspension. It has the advantages of not being acidic (which causes a decrease in the strength of wood and may cause the corrosion of the fasteners), being able to absorb water due to chemical bonding and being able to transfer the heat efficiently (Rassam et  al. 2010; Taghiyari et  al. 2017b). The outcomes have shown that because of the high thermal conductivity coefficient, nano-silver can delay thermal degradation, carbonization, and even pyrolysis of wood (Taghiyari 2011, 2012). The application of nano-oxides or nano-metals as the reinforcing agent for coatings can contribute to the improved opacity, mechanical, electrical properties, and better interaction between the surface and the coating layer (Deraman and Chandren 2019). Moreover, the introduction of such NPs, for example, SiO2 or TiO2, can provide the increase in thermal stability and flammable properties of various materials (Popescu and Pfriem 2020). Nano-silica has been intensively used as the compound for transparent waterborne polyurethane, multilayer UV-curable, fluorocarbon coatings, and many others. The addition of nano-SiO2 allows to obtain coatings with the improved mechanical behavior, hydrophobicity, interfacial adhesion, self-cleaning performance, and anti-ageing properties without compromising its transparency (Nkeuwa et al. 2014; Zhang et al. 2016b; Zhou et al. 2017). Furthermore, the incorporation of nano-silica into the coatings can also improve thermal stability and flammable properties of the materials. The nano-SiO2-modified coatings based on cyclic phosphate ester acid (PEA) exhibit the major decrease in mass loss, char index, flame spreading rate, total heat release, smoke production rate, total smoke, and heat release. The improvement in the outcomes results from the enhancement in char-forming ability, intumescence and antioxidation properties leading to the formation of stronger shielding effect in condensed phase, and creation of more compact intumescent char layer (Yan et al. 2017). The improved fire behavior due to the reinforcement with nano-SiO2 has been also confirmed in case of coatings

78

J. Kawalerczyk et al.

assembled by layer by layer (LbL) (Alongi et  al. 2013; Carosio et  al. 2013) and based on ammonium polyphosphate-pentaerythritol-melamine (Wang et al. 2010b). The LbL method has been also applied in case of nano-TiO2 and nano-ZnO-enriched coatings. Coating of wood with chitosan-sodium phytate/nano-TiO2-ZnO flame retardant system results in the significant improvement in flame retardancy and thermal stability of wood (Zhou and Fu 2020). Overall, the nano-oxides and nano-metals due to their unique properties are able to effectively reinforce both the innovative and already used systems of protection against fire (Table 2). These nanoparticles can contribute to the increase in thermal stability and flammable properties of solid wood and wood-based materials bonded with polymers and formaldehyde-containing adhesives.

Table 2  The effect of nano-oxides and nano-silver on the fire resistance of wood and wood-based composites Type of nanoparticles Nano-SiO2

Effect on fire resistance Way of introduction Improved fire resistance Polymer reinforcement of WPC

Improved fire resistance Urea-formaldehyde adhesive of particleboard reinforcement

Improved fire resistance Impregnating suspension of veneer Improved fire resistance Impregnation together with of wood furfuryl alcohol, mono-ethylene glycol, or paraffine Fire resistant coatings Surface treatment

Additional positive effects Weathering performance Mechanical properties Physical properties Adhesive consumption Mechanical properties Biological resistance No data available No data available

Mechanical properties Hygroscopicity Interfacial adhesion Self-cleaning performance Anti-ageing properties (continued)

Nanomaterials to Improve Fire Properties in Wood and Wood-Based Composite Panels

79

Table 2 (continued) Type of nanoparticles Nano-TiO2, Nano-ZnO

Effect on fire resistance Way of introduction Improved fire resistance Polymer reinforcement of WPC

Improved fire resistance Adhesive reinforcement of MDF and particleboard

Improved fire resistance Impregnating suspension of veneer Improved fire resistance Impregnating suspension of solid wood

Nano-silver

Fire resistant coatings Surface treatment Improved fire resistance Impregnating suspension of wood

Additional positive effects Mechanical properties Biological resistance Mechanical properties Physical properties Biological resistance No data available Mechanical properties Physical properties Biological resistance Leaching Weathering performance UV-protection Gas permeability No data available No data available

4 Carbon-Based Nanoparticles Carbon-based nanoparticles (CNs) comprise an interesting group of materials characterized by the outstanding, unprecedented properties and advanced structures, which are attractive for chemists, physicists, and materials scientists. These materials are used in many fields such as energy storage, automotive parts, filters, electronics, catalysts, medicine, and electromagnetic shields (Kumar and Kumbhat 2016; Yan et  al. 2016). An interesting possibility of application for nano-allotropes of carbon, particularly carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), is also the fire protection (Wang et al. 2017; Taghiyari et al. 2021a). CNT can be defined as the cylindrical large molecules consisting of the hexagonal arrangement of hybridized carbon atoms, which may be formed by rolling up a single or multiple sheets of graphene (Holban et  al. 2016). GNPs are platelet-like two-dimensional carbon structure with single or multi-layers of graphite (Kuan et  al. 2018). They were discovered in 1991 and 2004 (Iijima 1991; Novoselov et  al. 2004), respectively, which caused the revolutionary progress in the development of material sciences. Both the CNT and GNP are characterized by the superior stiffness, mechanical

80

J. Kawalerczyk et al.

strength, chemical resistance, light weight, hydrophobicity, and thermal and electrical conductivity (Allen et al. 2010; Nine et al. 2015; Gorgolis and Galiotis 2017; Łukawski et al. 2018a, b, 2022). They have been used to prepare promising multifunctional flame-resistant polymeric materials. The incorporation of CN, even in the small amount, usually less than 5%, have been reported to significantly improve the fire resistance of the most commonly applied polymers such as PP, PE, PS, and PLA (Kashiwagi et al. 2004; Costache et al. 2007; Hapuarachchi and Peijs 2010). Due to the positive impact on the combustibility of polymeric matrixes, both carbon nanotubes and graphene nanoplatelets have been extensively investigated in recent years in terms of potential application in WPC (Łukawski et al. 2022). It was found that the addition of CN contributes to the improvement in their mechanical properties, water absorption, wettability, surface roughness, scratch resistance, electrical conductivity, and biodegradability (Song et al. 2011; Sheshmani et al. 2013; Yaghoobi and Fereidoon 2018; Kaymakci et  al. 2019; Rajan et  al. 2021). Carbon-based nanoparticles have also aroused a great deal of interests due to their positive effect on fire retardancy of WPC. The obtained composites have significantly better thermal stability manifesting itself in the increased temperature of thermal degradation. It results from the favorable barrier properties causing a delay in the release and decomposition of volatile compounds. Moreover, CN have a considerably higher temperature of decomposition in comparison with raw WPCs (Fu et  al. 2010; Sheshmani et al. 2013; Ye et al. 2019). The positive effect on flammable properties of CNT- and GNP-reinforced composites determined using the LOI was confirmed by Zhang et al. (2018, 2019). However, results also show that too high concentration of CN results in the formation of agglomerates, which consequently can decrease the effectiveness of fire protection in case of CN-enriched materials. Carbon-based nanoparticles have been also investigated in terms of possible application to protect the particleboard against fire (Łukawski et al. 2019). It was found that pine wood particles coated with CNT aqueous dispersion (0.2%) are characterized by the significantly improved flammable properties. According to authors, it is the consequence of increased thermal conductivity of CNT and the enhancement in char layer formation. However, the incorporation of carbon nanotubes does not result in any significant changes in the combustibility, mechanical properties, and water absorption of manufactured CNT-modified particleboard probably due to the low quantity of nanoparticles or the addition of sodium dodecyl benzene sulfonate (SDBS) to the dispersion as a stabilizing agent. CNT can be also used to improve the flammable properties of MDF boards. The addition of carbon nano-modifier to wood fibers leads to the increase in fire behavior, thermal stability, and mechanical and physical properties of obtained panels (Dineshkumar 2014). Furthermore, the introduction of CNT to the UF adhesive can also result in the increase of mechanical, thermal, and physical properties of MDF boards due to the high thermal conductivity of CN. Moreover, it also causes a decrease in resin curing time and formaldehyde emission from the resultant panels (Kumar et al. 2015; Gul et al. 2021; Mazaheri et al. 2022). Studies have also shown that GNP can be incorporated in the production of plywood intended for flooring. Panels manufactured with the GNP-reinforced MUF resin have notably higher thermal conductivity. In

Nanomaterials to Improve Fire Properties in Wood and Wood-Based Composite Panels

81

addition, the introduction of GNT results in decreased VOC and formaldehyde emission (Seo et al. 2014). Although the increasing number of studies regarding the use of CN in order to improve the fire retardancy of polymer composites, synthetic resins or wood-based materials can be observed, the access to the research on the impregnation of solid wood itself is very limited. The outcomes presented by (Song et al. 2020) show that vacuum-assisted impregnation of thermally modified wood with CNT/GNP hybrids pre-absorbed with alkali lignin causes the significant reduction in total heat release, mass loss, flame spread, and CO2 yield during the combustion. Authors explained that impregnation with CN leads to creation of dense protective layer at the external wood surface, which slows down the pyrolytic reactions due to hindered mass and heat transfers. They also concluded that the research presented by them is a promising step toward the development of fire protection methods based on CN; however, much more research considering wood impregnation with carbon nano-derivatives is required to optimize the entire process. CNT are also used as the modifier for IFR coating systems based on, for example, epoxy resin (Ullah et  al. 2017) or polydiaminodiphenyl methane spirocyclic pentaerythritol bisphosphonate (PDSPB) (Kim et al. 2017). The presence of CNT enhances the residual weight of the char. Moreover, the created char layer is characterized by lower oxygen content, which improves the overall fire retardancy of coatings. Moreover, the application of CNT-modified surface treatment results in the reduction of gaseous products release and their decomposition during pyrolysis (Ullah et al. 2017). Promising results were also obtained in case of GNP-enriched water-based paint. When applied on the beech wood surface, it results in the improvement of onset of ignition, time to onset of glowing, back-darkening time, back-holing time, mass loss, and burnt area (Esmailpour et al. 2020a). The positive effect on protection against fire results from the superior thermal stability, thermal conductivity of CN, and their low reaction ability with the oxygen. Furthermore, due to unique properties of graphene, it can be also applied in coating to create superhydrophobic surfaces with increased UV resistance, abrasion resistance, and pencil hardness (Wan et al. 2015; Łukawski et al. 2018a; Yang et al. 2020). Increasing attention is being paid to carbon-based nanomaterials prepared with green methods used as the additive to the systems of wooden elements protection against fire. Due to their highly conductive nature and enhancement in char formation ability, it seems to be effective fire retardant for wooden materials (Table 3).

5 Health Risks and Toxicity The application of nanoparticles in wood protection against fire already demonstrated its great potential as they are used in many innovative ways to obtain products having desired characteristics. At the elemental and molecular level, they behave differently in terms of biological, chemical, and physical properties in comparison with their bulk size (Chaturvedi and Dave 2018; Patra and Lalhriatpuii

82

J. Kawalerczyk et al.

Table 3  The effect of carbon-based nanoparticles on the fire resistance of wood and wood-based composites Type of nanoparticles Carbon nanotubes (CNTs)

Graphene nanoplatelets (GNPs)

Effect on fire resistance Improved fire resistance of WPC

Improved fire resistance of MDF

Mixing with fibers Reinforcement of urea-­ formaldehyde adhesive

Improved fire resistance of wood Improved fire resistance of WPC Improved fire resistance of plywood

Impregnating suspension

Additional positive effects Mechanical properties Physical properties Wettability Surface roughness Scratch resistance Biological resistance Electrical conductivity Mechanical properties Physical properties Formaldehyde emission No data available

Polymer reinforcement

No data available

Melamine-urea-­ formaldehyde adhesive reinforcement

Improved fire resistance of wood

Impregnating suspension

Volatile organic compound emission Formaldehyde emission No data available

Way of introduction Polymer reinforcement

2020). Although people can be exposed to nanoparticles through inhalation, dermal contact, or ingestion, the effect of long-term exposure to nanotechnology is still not fully understood (Olawoyin 2018). It is known that the toxicity of NMs is strongly depended on their characteristics (Fig.  2). Due to the lack of clear knowledge regarding the impact of nanosized materials on human health, currently, there are no specific protocols for handling them, and they are treated like the ultrafine particles (Hoyt and Mason 2008; Iavicoli et al. 2009). In case of nanoclays, the toxicological evaluation has been carried out in animal models and cell lines. However, there are many conflicting conclusions between the studies performed in vitro and in vivo studies. The outcomes of in vitro studies suggest that nanoclays can induce cytotoxicity, but the observations vary depending on clay type, concentration, and experimental method. Most of the in vivo studies, on the other hand, reveal the lack of systemic toxicity at doses as high as 5  g/kg (Maisanaba et al. 2015; Brandelli 2018). According to Brandelli (2018), the main questions about their biological activity, ability to accumulate in organs, and bio-­ persistence still remain unanswered. Research performed by Kryuchkova et  al. (2016) determining the effect of nanoclays with the use of Paramecium caudatum classifies MMT as the material with very low or no toxicity. The investigations of cytotoxic effect caused by nano-sepiolite and sepiolite-containing nanocomposites show no significant reduction in cells viability at any experimental conditions and in all times of exposure, which indicates its nonhazardous nature (Fukushima et al.

Nanomaterials to Improve Fire Properties in Wood and Wood-Based Composite Panels

83

Fig. 2  Factors affecting the toxicity of NMs

2012, 2013). Due to increasing possibilities of application, wollastonite has been also investigated in terms of its toxicity. It has a low bio-persistence tested through in vitro and in vivo studies, which indicate the lack of toxic effect. Moreover, the exposure of animals to wollastonite by inhalation, intrapleural, intratracheal, and intraperitoneal ways does not lead to the interstitial fibrosis or tumors (Maxim and McConnell 2005; Maxim et al. 2014). On the contrary, the nano-silica, which currently is abundantly tested as a functional nano-filler, has been shown to cause the adverse effect on health in both in vitro and in vivo studies. The potential consequences of exposure to synthetic nano-silica may include lung cancer and inflammatory response; however, its toxicological potential strongly depends on the crystallinity and surface area of nanoparticles. The exposure to nano-SiO2 is significantly less harmful in case of sols and gels because NPs are immobilized within the matrix; however, in case of low-density fumed silica and freeze-dried nanosized particles, the right precautionary measures must be implemented (Napierska et al. 2010). Metallic NPs are vastly investigated as the additives for wood and wood-­ based material protection systems. Their mechanism of toxicity is mainly attributed to the dissociation of metal ion from the NP when exposed to biological fluids or cells (Girigoswami 2018). Both vitro and in vivo studies show that nanoparticles could induce the production of reactive oxygen – a mechanism leading to toxicity (Sengul and Asmatulu 2020). However, the relationship between the nanoparticles and their surroundings still remains unclear. Much more studies are required to clearly conclude the safety of functional nanomaterials. Overall, the toxicity of nano-metal oxides may differ depending on the oxidation state, ligands, solubility, morphology, and environmental and health conditions (Sengul and Asmatulu 2020). In many studies, some serious concerns have been expressed about potential health

84

J. Kawalerczyk et al.

risks of nano-silver and nano-TiO2 due to the toxic effect on cells affecting cellular growth and multiplication. Furthermore, since carbon-based nanoparticles increasingly attract the attention of scientists, their toxicity has been also determined in many studies. It was found that the toxic potential of CNT is reported in various animal models and cell lines, and it varies depending on the characteristics of NPs (Francis and Devasena 2018). Studies performed on mice show that the exposure to CNT can cause cancerous tumor growth, inflammation, and lesions of tissues in the similar way as the exposure to asbestos (Olawoyin 2018). The health and environmental risks associated with the incorporation of nanomaterials into the wood protection against fire should be taken into account. However, more studies are required in order to fully understand the toxicity of nanomaterials and the relationship between their properties and the potential health issues. Moreover, the standardization for testing methods and safety regulations has to be developed in order to allow the safe use of nanoparticles in the protection of wood (Napierska et al. 2010; Pielichowski and Michalowski 2014).

6 Summary Nanotechnology is a fast-growing branch of science focused on the unexplored functional characteristics of the matter representing a nanometer size range. Nanomaterials are the objects of extraordinary scientific interests because they display totally innovative and unique properties when compared with their macro-­ sized counterparts. As of today, the researchers are working on developing the methods to control the composition, size, and homogeneity of the nanostructures to explore new possible ways of their applications. Certainly, one of the promising ways of using them is the protection of wood and wood-based composites against fire. Their flame retarding effect on the properties of these materials is due to the barrier properties to the oxygen and heat, enhancement in char formation, and reduction in the yield of flammable gases, CO and CO2, during the combustion. Furthermore, they contribute to the faster release of noncombustible gases and the increase in dimensional stability and thermal conductivity. Their highly conductive nature prevents the local accumulation of heat and consequently reduces the spread of fire. Mineral nanoparticles such as montmorillonite, sepiolite, and wollastonite show a great potential in improving the flammable properties of both wood plastic composites and other wood-based materials such as fiberboards, particleboards, and plywood. Moreover, they are also used in coatings and in the protection of solid wood species, most often in the combination with other fire proofing measures. The great application potential in this field is also shown by nano-silica, nano-metals, and nano-metal oxides. Besides solid wood and coatings, nanomaterials can also improve the fire protection of wood-based composite panels bonded with both polymers and formaldehyde-containing resins. Moreover, carbon-based nanomaterials such as carbon nanotubes and graphene nanoplatelets currently attract attention of many scientists around the world. They were incorporated in the advanced fire

Nanomaterials to Improve Fire Properties in Wood and Wood-Based Composite Panels

85

protection systems for wooden elements and products. It is not just nanoparticles’ ability as a flame retardant that makes them advantageous to use. They contribute to the increase in mechanical, physical, and thermal properties of materials. Moreover, in some cases, nanoparticles also improve biodegradability, weathering performance of wood products, and the adhesion of coatings. However, although the mineral nanoparticles appear to be harmless to human health, there are studies indicating that the other NPs, which have been described, may cause the adverse health side effects. As stated by the scientists, more research in this matter is needed to unequivocally state if in some cases the risks associated with implementation of nanotechnology do not exceed the benefits. Overall, in recent years, promising research on the incorporation of nanomaterials in the field of protecting wood and wood-based material against fire become very popular. The results are very favorable and bode well for the future; however, there is still lack or shortage of knowledge in some areas that require further studies and explanations.

References Ahmed L, Zhang B, Shen R et al (2018) Fire reaction properties of polystyrene-based nanocomposites using nanosilica and nanoclay as additives in cone calorimeter test. J Therm Anal Calorim 132:1853–1865 Alexandre M, Dubois P (2000) Polymer-layered silicate nanocomposites: preparation, properties and uses of a new class of materials. Mater Sci Eng R 28:1–63 Alias AH, Norizan MN, Sabaruddin FA et al (2021) Hybridization of MMT/lignocellulosic fiber reinforced polymer nanocomposites for structural applications: a review. Coatings 11:1355 Allen MJ, Tung VC, Kaner RB (2010) Honeycomb carbon: a review of graphene. Chem Rev 110:132–145 Alongi J, Carosio F, Frache A, Malucelli G (2013) Layer by layer coatings assembled through dipping, vertical or horizontal spray for cotton flame retardancy. Carbohydr Polym 92:114–119 Ayrilmis N, Dundar T, Candan Z, Akbulut T (2009) Wettability of fire retardant treated laminated veneer lumber (LVL) manufactured from veneers dried at different temperatures. Bioresources 4:1536–1544 Bahrani B, Hemmati V, Zhou A, Quarles SL (2018) Effects of natural weathering on the fire properties of intumescent fire-retardant coatings. Fire Mater 42:413–423 Bak M, Molnár F, Németh R (2019) Improvement of dimensional stability of wood by silica nanoparticles. Wood Mater Sci Eng 14:48–58 Bari E, Taghiyari HR, Schmidt O et al (2015) Effects of nano-clay on biological resistance of wood-­ plastic composite against five wood-deteriorating fungi. Maderas-Cienc Tecnol 17:205–212 Beecher JF (2007) Wood, trees and nanotechnology. Nat Nanotechnol 2:466–467 Bekhta P, Müller M, Hunko I (2020) Properties of thermoplastic-bonded plywood: effects of the wood species and types of the thermoplastic films. Polymers 12:2582 Berglund LA, Burgert I (2018) Bioinspired wood nanotechnology for functional materials. Adv Mater 30:1704285 Bertini F, Canetti M, Audisio G et al (2006) Characterization and thermal degradation of polypropylene–montmorillonite nanocomposites. Polym Degrad Stabil 91:600–605 Bharadwaj RK, Mehrabi AR, Hamilton C et al (2002) Structure–property relationships in cross-­ linked polyester–clay nanocomposites. Polymer 43:3699–3705 Bhushan B (2017) Introduction to nanotechnology. In: Springer handbook of nanotechnology. Springer, pp 1–19

86

J. Kawalerczyk et al.

Bilotti E, Fischer HR, Peijs T (2008) Polymer nanocomposites based on needle-like sepiolite clays: effect of functionalized polymers on the dispersion of nanofiller, crystallinity, and mechanical properties. J Appl Polym Sci 107:1116–1123 Bradley EL, Castle L, Chaudhry Q (2011) Applications of nanomaterials in food packaging with a consideration of opportunities for developing countries. Trends Food Sci Technol 22:604–610 Brandelli A (2018) Toxicity and safety evaluation of nanoclays. In: Nanomaterials: ecotoxicity, safety, and public perception. Springer, pp 57–76 Bueno AF, Bañón MN, De Morentín LM, García JM (2014) Treatment of natural wood veneers with nano-oxides to improve their fire behaviour. In: IOP Conference Series: Materials Science and Engineering. IOP Publishing, p 012021 Camino G, Costa L (1988) Performance and mechanisms of fire retardants in polymers—a review. Polym Degrad Stabil 20:271–294 Camino G, Tartaglione G, Frache A et al (2005) Thermal and combustion behaviour of layered silicate–epoxy nanocomposites. Polym Degrad Stabil 90:354–362 Carosio F, Di Blasio A, Cuttica F et al (2013) Flame retardancy of polyester fabrics treated by spray-assisted layer-by-layer silica architectures. Ind Eng Chem Res 52:9544–9550 Chan JX, Wong JF, Hassan A et al (2020) Mechanical properties of wollastonite reinforced thermoplastic composites: a review. Polym Compos 41:395–429 Chaturvedi S, Dave PN (2018) Chapter 59 – nanomaterials: environmental, human health risk. In: Mustansar Hussain C (ed) Handbook of Nanomaterials for Industrial Applications. Elsevier, pp 1055–1062 Chigwada G, Kandare E, Wang D et  al (2008) Thermal stability and degradation kinetics of polystyrene/organically-modified montmorillonite nanocomposites. J Nanosci Nanotechnol 8:1927–1936 Chivrac F, Pollet E, Schmutz M, Avérous L (2010) Starch nano-biocomposites based on needle-­ like sepiolite clays. Carbohydr Polym 80:145–153 Chu J, Xiang C, Sue H-J, Hollis RD (2000) Scratch resistance of mineral-filled polypropylene materials. Polym Eng Sci 40:944–955 Clausen C (2012) Enhancing durability of wood-based composites with nanotechnology. USDA Forest Service, Forest Products Laboratory, General Technical Report, FPL-GTR-218, 2012; pp 8–12, 218:8–12 Costache MC, Heidecker MJ, Manias E et al (2007) The influence of carbon nanotubes, organically modified montmorillonites and layered double hydroxides on the thermal degradation and fire retardancy of polyethylene, ethylene–vinyl acetate copolymer and polystyrene. Polymer 48:6532–6545 Cyrankowski M, Osipiuk J, Czarniak P, Spychaj L (2013) Historic feature of wood fire protection. Ann WULS – SGGW Wood Technol 82:140–144 da Silva APS, Ferreira BS, Favarim HR, Silva MFF, Silva JVF, Azambuja MA, Campos CI (2019) Physical properties of medium density fiberboard produced with the addition of ZnO nanoparticles. Bioresources 14:1618–1625 de Cademartori PHG, Artner MA, de Freitas RA, Magalhães WLE (2019) Alumina nanoparticles as formaldehyde scavenger for urea-formaldehyde resin: rheological and in-situ cure performance. Compos Part B-Eng 176:107281 Deka BK, Maji TK (2011) Study on the properties of nanocomposite based on high density polyethylene, polypropylene, polyvinyl chloride and wood. Compos Part A-Appl Sci 42:686–693 Deraman AF, Chandren S (2019) Fire-retardancy of wood coated by titania nanoparticles. In: AIP Conference Proceedings. AIP Publishing LLC, p 020022 Devi RR, Maji TK (2012) Effect of nano-SiO2 on properties of wood/polymer/clay nanocomposites. Wood Sci Technol 46:1151–1168 Devi RR, Maji TK (2013) Effect of nanofillers on flame retardancy, chemical resistance, antibacterial properties and biodegradation of wood/styrene acrylonitrile co-polymer composites. Wood Sci Technol 47:1135–1152

Nanomaterials to Improve Fire Properties in Wood and Wood-Based Composite Panels

87

Dineshkumar S (2014) Use of multi-walled carbon nanotubes (MWCNTs) in medium density fiberboard to increase the fire retardancy, PhD Thesis. Universiti Malaysia Pahang Ding Q, Zhang Z, Dai X, Li M, Mai K (2019) Effect of hybrid wollastonite with different nucleation and morphology on the crystallization and mechanical properties of polypropylene. Polym Compos 40:E638–E646 Dong Y, Yan Y, Zhang S, Li J, Wang J (2015) Flammability and physical–mechanical properties assessment of wood treated with furfuryl alcohol and nano-SiO2. Eur J Wood Wood Prod 73:457–464 Doosthoseini K, Zarea-Hosseinabadi H (2010) Using Na+ MMT nanoclay as a secondary filler in plywood manufacturing. J Indian Acad Wood Sci 7:58–64 Dukarska D (2019) Właściwości wybranych tworzyw drewnopochodnych wytwarzanych z udziałem nano-SiO2. Wydawnictwo Uniwersytetu Przyrodniczego w Poznaniu Dukarska D, Bartkowiak M (2016) The effect of organofunctional nanosilica on the cross-linking process and thermal resistance of UF resin. J Polym Res 23:166 Dukarska D, Czarnecki R (2016) Fumed silica as a filler for MUPF resin in the process of manufacturing water-resistant plywood. Eur J Wood Wood Prod 74:5–14 Dukarska D, Cofta G, Krzykowska J (2017) Resistance of selected wood-based materials glued with nano-SiO2/UF resin to A. niger infestation. Ann WULS – SGGW Wood Technol 97:114–117 Esmailpour A, Taghiyari HR, Nouri P, Jahangiri A (2018) Fire-retarding properties of nanowollastonite in particleboard. Fire Mater 42:306–315 Esmailpour A, Majidi R, Taghiyari HR, Ganjkhani M, Mohseni Armaki SM, Papadopoulos AN (2020a) Improving fire retardancy of beech wood by graphene. Polymers 12:303 Esmailpour A, Taghiyari HR, Ghorbanali M, Mantanis GI (2020b) Improving fire retardancy of medium density fiberboard by nano-wollastonite. Fire Mater 44:759–766 Esmailpour A, Taghiyari HR, Majidi R et al (2021) Nano-wollastonite to improve fire retardancy in medium-density fiberboard (MDF) made from wood fibers and camel-thorn. Wood Mater Sci Eng 16:161–165 Evans P, Matsunaga H, Kiguchi M (2008) Large-scale application of nanotechnology for wood protection. Nat Nanotechnol 3:577–577 Farahani MRM, Banikarim F (2013) Effect of nano-zinc oxide on decay resistance of wood-plastic composites. Bioresources 8:5715–5720 Favarim HR, Leite LO (2018) Performance of ZnO nanoparticles for fire retardant and UV protection of pine wood. Bioresources 13:6963–6969 Francis AP, Devasena T (2018) Toxicity of carbon nanotubes: a review. Toxicol Ind Health 34:200–210 Fridley KJ (2002) Wood and wood-based materials: current status and future of a structural material. J Mater Civil Eng 14:91–96 Fu S, Song P, Yang H, Jin Y, Lu F, Ye J, Wu Q (2010) Effects of carbon nanotubes and its functionalization on the thermal and flammability properties of polypropylene/wood flour composites. J Mater Sci 45:3520–3528 Fu Q, Medina L, Li Y, Carosio F, Hajian A, Berglund LA (2017) Nanostructured wood hybrids for fire-retardancy prepared by clay impregnation into the cell wall. ACS Appl Mater Interfaces 9:36154–36163 Fukushima K, Wu M-H, Bocchini S, Rasyida A, Yang MC (2012) PBAT based nanocomposites for medical and industrial applications. Mater Sci Eng C 32:1331–1351 Fukushima K, Rasyida A, Yang M-C (2013) Characterization, degradation and biocompatibility of PBAT based nanocomposites. Appl Clay Sci 80:291–298 Gatoo MA, Naseem S, Arfat MY, Mahmood Dar A, Qasim K, Zubair S (2014) Physicochemical properties of nanomaterials: implication in associated toxic manifestations. Biomed Res Int 2014:e498420 Ghasemi E, Kord B (2009) Long-term water absorption behaviour of polypropylene/wood flour/ organoclay hybrid nanocomposite. Iran Polym J 18(9(111)):683–691

88

J. Kawalerczyk et al.

Ghasemzadeh G, Momenpour M, Omidi F, Hosseini MR, Ahani M, Barzegari A (2014) Applications of nanomaterials in water treatment and environmental remediation. Front Environ Sci Eng 8:471–482 Ghofrani M, Haghdan S, NicKhah V, Ahmadi K (2015) Improvement of physical and mechanical properties of particleboard made of apple tree pruning and sunflower stalk using titanium oxide nanoparticles. Eur J Wood Wood Prod 73:661–666 Ghorbani M, Akhtari M, Taghiyari HR, Kalantari A (2012) Effects of silver and zinc-oxide nanoparticles on gas and liquid permeability of heat-treated paulownia wood. Austrian J For Sci 129:106–123 Girigoswami K (2018) Toxicity of metal oxide nanoparticles. In: Saquib Q, Faisal M, Al-Khedhairy A, Altar A. (Eds) Cellular and molecular toxicology of nanoparticles. Advances in Experimental Medicine and Biology, vol 1048. Springer, Cham Gonçalves C, Paiva NT, Ferra JM, Martins J, Magalhães F, Barros-Timmons A, Carvalho L (2018) Utilization and characterization of amino resins for the production of wood-based panels with emphasis on particleboards (PB) and medium density fibreboards (MDF). A review. Holzforschung 72:653–671 Gorgolis G, Galiotis C (2017) Graphene aerogels: a review. 2D Materials 4:032001 Grexa O, Horváthová E, Lehocký P (1999) Flame retardant treated plywood. Polym Degrad Stabil 64:529–533 Grześkowiak W, Cofta G, Janiak G, Kwaśniewska-Sip P (2016) Influence of impregnation time on the degree of wood-based materials fire protection. Ann WULS – SGGW Wood Technol 94:278–282 Gul W, Alrobei H, Shah SRA, Khan A, Hussain A, Asiri AM, Kim J (2021) Effect of embedment of MWCNTs for enhancement of physical and mechanical performance of medium density fiberboard. Nano 11:29 Guo F, Aryana S, Han Y, Jiao Y (2018) A review of the synthesis and applications of polymer– nanoclay composites. Appl Sci 8:1696 Haghighi A, Taghiyari HR, Karimi AN (2013a) Study on fire-retarding properties of nano-­ wollastonite in fir wood (Abies alba). Iran J Wood Paper Sci Res 28:252–265 Haghighi PA, Taghiyari HR, Naghi KA (2013b) The optimum level of nano-wollastonite consumption as fire-retardant in poplar wood (Populus nigra). Int J Nano Dimension 4(2(14)):141–151 Hao X, Zhou H, Xie Y, Xiao Z, Wang H, Wang Q (2019) Mechanical reinforcement and creep resistance of coextruded wood flour/polyethylene composites by shell-layer treatment with nano-and micro-SiO2 particles. Polym Compos 40:1576–1584 Hapuarachchi TD, Peijs T (2010) Multiwalled carbon nanotubes and sepiolite nanoclays as flame retardants for polylactide and its natural fibre reinforced composites. Compos Part A-Appl Sci 41:954–963 Harada T, Uesugi S, Masuda H (2006) Fire resistance of thick wood-based boards. J Wood Sci 52:544–551 Hassani V, Taghiyari HR, Schmidt O, Maleki S, Papadopoulos AN (2019) Mechanical and physical properties of oriented strand lumber (OSL): the effect of fortification level of nanowollastonite on UF resin. Polymers 11:1884 Hazarika A, Maji TK (2013) Study on the properties of wood polymer nanocomposites based on melamine formaldehyde-furfuryl alcohol copolymer and modified clay. J Wood Chem Technol 33:103–124 Heiden P, Matuana L, Dawson-Andoh B (2005) Nanotechnology: a novel approach to prevent biocide leaching. https://archive.epa.gov/ncer/publications/web/html/heiden.html Hernandez V, Romero R, Arias S, Contreras D (2022) A novel method for calcium carbonate deposition in wood that increases carbon dioxide concentration and fire resistance. Coatings 12:72 Hochella MF Jr, Lower SK, Maurice PA, Penn RL, Sahai N, Sparks DL, Twining BS (2008) Nanominerals, mineral nanoparticles, and earth systems. Science 319:1631–1635

Nanomaterials to Improve Fire Properties in Wood and Wood-Based Composite Panels

89

Holban AM, Grumezescu AM, Andronescu E (2016) Inorganic nanoarchitectonics designed for drug delivery and anti-infective surfaces. In: Surface chemistry of nanobiomaterials. Elsevier, pp 301–327 Hosseyni MJ, Rahimi S, Faezipour M, Faezipour MM (2014) Effect of nanoclay particles on the properties of particleboards. J Basic Appl Sci Res 4:280–287 Hoyt VW, Mason E (2008) Nanotechnology: emerging health issues. J Chem Health Saf 15:10–15 Hu X, Sun Z, Zhu X, Sun Z (2020) Montmorillonite-synergized water-based intumescent flame retardant coating for plywood. Coatings 10:109 Hu X, Luo Y, Liu W, Sun Z (2022) Synergistic interaction between inorganic layered materials and intumescent fire retardants for advanced fire protection. Carbon 187:290–301 Huang G, Gao J, Li Y, Han L, Wang X (2010) Functionalizing nano-montmorillonites by modified with intumescent flame retardant: preparation and application in polyurethane. Polym Degrad Stab 95:245–253 Huang H-L, Lin C-C, Hsu K (2015) Comparison of resistance improvement to fungal growth on green and conventional building materials by nano-metal impregnation. Build Environ 93:119–127 Huuhilo T, Martikka O, Butylina S, Kärki T (2010a) Impact of mineral fillers to the moisture resistance of wood-plastic composites. Balt For 16:126–131 Huuhilo T, Martikka O, Butylina S, Kärki T (2010b) Mineral fillers for wood–plastic composites. Wood Mater Sci Eng 5:34–40 Iavicoli S, Rondinone BM, Boccuni F (2009) Occupational safety and health’s role in sustainable, responsible nanotechnology: gaps and needs. Hum Exp Toxicol 28:433–443 Iijima S (1991) Helical microtubules of graphitic carbon. Nature 354:56–58 Izadyar S, Hamzezadeh R, Efhamisisi D, Karimi Mazraeshahi A (2019) The evaluation of decay resistance and dimentional stability of poplar wood treated with Styrene/Nano wellastonite. Iran J Wood Paper Ind 10:445–455 Izadyar S, Hamzezadeh R, Efhamisisi D (2020) Fire resistance and mechanical properties of nano-­ wollastonite/styrene-treated poplar wood. Iran J Wood Paper Sci Res 35:46–60 Kačíková D, Kubovský I, Eštoková A, Kačík F, Kmeťová E, Kováč J, Ďurkovič J (2021) The influence of nanoparticles on fire retardancy of pedunculate oak wood. Nano 11:3405 Karaman A, Yıldırım MN, Yaşar ŞŞ (2019) Determination of modulus of elasticity and bending strength of wood material impregnated with nanoparticle silicon dioxide (SiO2). Turk J For 20:50–56 Karimi A, Taghiyari HR, Fattahi A, Karimi S, Ebrahimi G, Tarmian A (2013) Effects of wollastonite nanofibers on biological durability of poplar wood (Populus nigra) against Trametes versicolor. Bioresources 8:4134–4141 Kashiwagi T, Grulke E, Hilding J, Groth K, Harris R, Butler K, Shields J, Kharchenko S, Douglas J (2004) Thermal and flammability properties of polypropylene/carbon nanotube nanocomposites. Polymer 45:4227–4239 Kawalerczyk J, Dziurka D, Mirski R, Grześkowiak W (2019) The effect of veneer impregnation with a mixture of potassium carbonate and urea on the properties of manufactured plywood. Drewno 62:107–116 Kawalerczyk J, Dziurka D, Mirski R, Siuda J, Szentner K (2020) The effect of nanocellulose addition to phenol-formaldehyde adhesive in water-resistant plywood manufacturing. Bioresources 15:5388–5401 Kawalerczyk J, Dziurka D, Mirski R, Siuda J, Babicka M (2021a) Possibility of use of NCC-­ reinforced melamine-urea-formaldehyde adhesive in plywood manufacturing. Drvna Ind 72(3):279–289 Kawalerczyk J, Dziurka D, Mirski R, Siuda J (2021b) The reduction of adhesive application in plywood manufacturing by using nanocellulose-reinforced urea-formaldehyde resin. J Appl Polym Sci 138:49834

90

J. Kawalerczyk et al.

Kaymakci A (2020) Effect of sepiolite clay nanofibers on physical, mechanical, and thermal properties of wood-plastic nanocomposites. J Thermoplast Compos Mater. https://doi. org/10.1177/0892705720939171 Kaymakci A, Birinci E, Ayrilmis N (2019) Surface characteristics of wood polypropylene nanocomposites reinforced with multi-walled carbon nanotubes. Compos Part B-Eng 157:43–46 Khan ZI, Habib U, Mohamad ZB, Rahmat ARB, Abdullah NASB (2022) Mechanical and thermal properties of sepiolite strengthened thermoplastic polymer nanocomposites: a comprehensive review. Alex Eng J 61:975–990 Khojasteh Khosro S, Taghipour Javy M (2018) The effect of nano wollastonite on the fire resistance and the adhesion properties of water based acrylic coating in wood surface. Iran J Wood Paper Sci Res 33:166–178 Kiaei M, Kord B, Samariha A, Moghdam YR, Farsi M (2017) Mechanical, flammability, and morphological properties of nano-composite plastic based on hardwood flour high-density polyethylene embedding by nano-zinc oxide. Bioresources 12:6518–6528 Kim H, Park J-W, Kim H-J, Di Sia P (2017) Flame retardant nano-composites containing nano-­ fillers. Sci Appl Tailored Nanostruct 2017:2–24 Kizilkaya A, Aydemir D, Sm O, Istek A (2020) Effects of different nano fillers on the physical and mechanical properties of medium density fiberboards (MDF). J Bartin Fac For 22:878–885 Kryuchkova M, Danilushkina A, Lvov Y, Fakhrullin R (2016) Evaluation of toxicity of nanoclays and graphene oxide in vivo: a Paramecium caudatum study. Environ Sci Nano 3:442–452 Kuan CF, Chiang CL, Lin SH, Huang WG, Hsieh WY, Shen MY (2018) Characterization and properties of graphene nanoplatelets/XNBR nanocomposites. Polym Polym Compos 26:59–68 Kumar N, Kumbhat S (2016) Carbon-based nanomaterials. In: Essentials in nanoscience and nanotechnology. Wiley, pp 189–236 Kumar V, Tyagi L, Sinha S (2011) Wood flour–reinforced plastic composites: a review. De Gruyter. https://doi.org/10.1515/REVCE.2011.006 Kumar A, Gupta A, Sharma KV (2015) Thermal and mechanical properties of urea-formaldehyde (UF) resin combined with multiwalled carbon nanotubes (MWCNT) as nanofiller and fiberboards prepared by UF-MWCNT. Holzforschung 69:199–205 Lakshmi MS, Narmadha B, Reddy BSR (2008) Enhanced thermal stability and structural characteristics of different MMT-clay/epoxy-nanocomposite materials. Polym Degrad Stabil 93:201–213 Lei H, Du G, Pizzi A, Celzard A (2008) Influence of nanoclay on urea-formaldehyde resins for wood adhesives and its model. J Appl Polym Sci 109:2442–2451 LeVan SL, Winandy JE (1990) Effects of fire retardant treatments on wood strength: a review. Wood Fiber Sci 22:113–131 Lewandowska M, Zagorski A, Kurzydlowski KJ (2010) Mechanical and physical properties of nano-metals. In: Materials science forum. Trans Tech Publ, pp 1110–1113 Li X, Li J, Li J, Gao Q (2015) Effect of sepiolite filler in malamine-urea-formaldehyde resin on the properties of three-ply plywood. BioRes 10:6624–6634 Li S, Wang X, Xu M, Liu L, Wang W, Gao S, Li B (2021) Effect of a biomass based waterborne fire retardant coating on the flame retardancy for wood. Polym Adv Technol 32:4805–4814 Lidén G (2011) The European commission tries to define nanomaterials. Ann Occup Hyg 55:1–5 Liu M, Pu M, Ma H (2012) Preparation, structure and thermal properties of polylactide/sepiolite nanocomposites with and without organic modifiers. Compos Sci Technol 72:1508–1514 Liu C, Mei C, Xu B, Jiang M, Chen W, Zhou G, Wang K (2019) Effect of the nanosilica content in the shell of coextruded wood-plastic composites to enhance the ultraviolet aging resistance. Polym Adv Technol 30:162–169 Liu R, Liu X, Zhang Y, Liu J, Gong C, Dong Y, Li J, Shi J, Wu M (2020) Paraffin pickering emulsion stabilized with nano-SiO2 designed for wood impregnation. Forests 11:726 Łukawski D, Lekawa-Raus A, Lisiecki F, Koziol K, Dudkowiak A (2018a) Towards the development of superhydrophobic carbon nanomaterial coatings on wood. Prog Org Coat 125:23–31

Nanomaterials to Improve Fire Properties in Wood and Wood-Based Composite Panels

91

Łukawski D, Lisiecki F, Dudkowiak A (2018b) Coating cellulosic materials with graphene for selective absorption of oils and organic solvents from water. Fiber Polym 19:524–530 Łukawski D, Grześkowiak W, Dukarska D, Mazela B, Lekawa-Raus A, Dudkowiak A (2019) The influence of surface modification of wood particles with carbon nanotubes on properties of particleboard glued with phenol-formaldehyde resin. Drewno 62:93–105 Łukawski D, Hochmańska-Kaniewska P, Janiszewska D, Wróblewski G, Patmore J, Lekawa-Raus A (2022) Enriching WPCs and NFPCs with carbon nanotubes and graphene. Polymers 14:745 Luyt AS, Dramićanin MD, Antić Ž, Djoković V (2009) Morphology, mechanical and thermal properties of composites of polypropylene and nanostructured wollastonite filler. Polym Test 28:348–356 Maisanaba S, Pichardo S, Puerto M, Gutierrez-Praena D, Camean AM, Jos A (2015) Toxicological evaluation of clay minerals and derived nanocomposites: a review. Environ Res 138:233–254 Marzbani P, Mohammadnia-afrouzi Y (2014) Investigation on leaching and decay resistance of wood treated with nano-titanium dioxide. Adv Environ Biol 8(10):974–979 Marzbani P, Afrouzi YM, Omidvar A (2015) The effect of nano-zinc oxide on particleboard decay resistance. Maderas-Cienc Tecnol 17:63–68 Maxim LD, McConnell EE (2005) A review of the toxicology and epidemiology of wollastonite. Inhal Toxicol 17:451–466 Maxim LD, Niebo R, Utell MJ et  al (2014) Wollastonite toxicity: an update. Inhal Toxicol 26:95–112 Mazaheri M, Moghimi H, Taheri RA (2022) Urea impregnated multiwalled carbon nanotubes; a formaldehyde scavenger for urea formaldehyde adhesives and medium density fiberboards bonded with them. J Appl Polym Sci 139:51445 Mazela B, Batista A, Grześkowiak W (2020) Expandable graphite as a fire retardant for cellulosic materials—a review. Forests 11:755 Milewski JV, Katz HS (1987) Handbook of reinforcements for plastics. Van Nostrand Reinhold, New York Mirski R, Dziurka D, Łęcka J (2011) Potential of shortening pressing time or reducing pressing temperature for plywood resinated with PF resin modified using alcohols and esters. Eur J Wood Wood Prod 69:317–323 Mirski R, Dziurka D, Chuda-Kowalska M, Wieruszewski M, Kawalerczyk J, Trociński A (2020) The usefulness of pine timber (Pinus sylvestris L.) for the production of structural elements. Part I: evaluation of the quality of the pine timber in the bending test. Materials 13:3957 Mishra AK, Luyt AS (2008) Effect of sol–gel derived nano-silica and organic peroxide on the thermal and mechanical properties of low-density polyethylene/wood flour composites. Polym Degrad Stabil 93:1–8 Mohd Zaini NA, Ismail H, Rusli A (2017) Short review on sepiolite-filled polymer nanocomposites. Polym-Plast Technol 56:1665–1679 Muñoz F, Moya R, Muñoz F, Moya R (2018) Effect of nanoclay-treated UF resin on the physical and mechanical properties of plywood manufactured with wood from tropical fast growth plantations. Maderas-Cienc Tecnol 20:11–24 Napierska D, Thomassen LC, Lison D, Martens JA, Hoet PH (2010) The nanosilica hazard: another variable entity. Part Fibre Toxicol 7:1–32 Nazir MS, Mohamad Kassim MH, Mohapatra L, Gilani MA, Raza MR, Majeed K (2016) Characteristic properties of nanoclays and characterization of nanoparticulates and nanocomposites. In: Jawaid M, Qaiss A, Bouhfid R (eds) Nanoclay reinforced polymer composites. Springer Singapore, Singapore, pp 35–55 Nemati M, Khademieslam H, Talaiepour M, Bazyar B, Khakifirooz A (2013) Studying the effect of nanoclay on thermal properties of wood flour/recycled polystyrene composite. J Basic Appl Sci Res 3:789–794 Nikolaeva M, Kärki T (2013) Influence of mineral fillers on the fire retardant properties of wood-­ polypropylene composites. Fire Mater 37:612–620

92

J. Kawalerczyk et al.

Nine MJ, Cole MA, Tran DN, Losic D (2015) Graphene: a multipurpose material for protective coatings. J Mater Chem A 3:12580–12602 Nkeuwa WN, Riedl B, Landry V (2014) Wood surfaces protected with transparent multilayer UV-cured coatings reinforced with nanosilica and nanoclay. Part I: morphological study and effect of relative humidity on adhesion strength. J Coat Technol Res 11:283–301 Norani AK, Hashim R, Sulaiman O, Hiziroglu S, Ujang S, Wan Nadhari WNA (2017) Biodegradation behaviour of particleboard bonded with modified PVOH/oil palm starch and nano silicon dioxide. Iran J Energy Environ 8:269–273 Novoselov KS, Geim AK, Morozov SV, Jiang DE, Zhang Y, Dubonos SV, Grigorieva IV, Firsov AA (2004) Electric field effect in atomically thin carbon films. Science 306:666–669 Nur Izreen Farah A, Zaidon A, Anwar UMK, Rabiatol-Adawiah MA, Lee SH (2021) Improved performance of wood polymer nanocomposite impregnated with metal oxide nanoparticle-­ reinforced phenol formaldehyde resin. J Trop For Sci 33:77–87 Okada A, Usuki A (2006) Twenty years of polymer-clay nanocomposites. Macromol Mater Eng 291:1449–1476 Olawoyin R (2018) Nanotechnology: the future of fire safety. Saf Sci 110:214–221 Olivato JB, Marini J, Pollet E, Yamashita F, Grossmann MVE, Avérous L (2015) Elaboration, morphology and properties of starch/polyester nano-biocomposites based on sepiolite clay. Carbohyd Polym 118:250–256 Olivato JB, Marini J, Yamashita F, Pollet E, Grossmann MVE, Avérous L (2017) Sepiolite as a promising nanoclay for nano-biocomposites based on starch and biodegradable polyester. Mater Sci Eng C-Mater 70:296–302 Ozcifci A, Kara ME, Kaymakci A (2018) Impact of PF and MUF adhesives modified with TiO2 and SiO2 on the adhesion strength. Wood Res 63:75–84 Özdemir F, Çot A, Alma H (2018) Effect of sepiolit mineral on thermal properties and thermal conductivity of wood plastic composite materials. Turk J Forestry 19:205–209 Papadopoulos AN (2020) Advances in wood composites. Multidisciplinary Digital Publishing Institute Patra A, Lalhriatpuii M (2020) Progress and prospect of essential mineral nanoparticles in poultry nutrition and feeding—a review. Biol Trace Elem Res 197:233–253 Pielichowski K, Michalowski S (2014) Nanostructured flame retardants: performance, toxicity, and environmental impact. In: Health and environmental safety of nanomaterials. Elsevier, pp 251–277 Pofit-Szczepańska M, Jaskółowski W, Mazela B (2014) Palność drewna i wyrobów lignocelulozowych: teoretyczne podstawy mechanizmów rozkładu termicznego, sposobów spalania się, modyfikacji przeciwogniowych oraz europejskich wymagań klasyfikacji pożarowej. Fundacja Edukacja i Technika Ratownictwa Poole CP Jr, Owens FJ (2003) Introduction to nanotechnology. Wiley Popescu C-M, Pfriem A (2020) Treatments and modification to improve the reaction to fire of wood and wood based products—an overview. Fire Mater 44:100–111 Poshtiri AH, Taghiyari HR, Karimi AN (2014) Fire-retarding properties of nano-wollastonite in solid wood. Philipp Agric Sci 97:52–59 Pour MF, Mehdinia M, Kiamahalleh MV, Hoseini KD, Hatefnia H, Dorieh A (2021) Biological durability of particleboard: fungicidal properties of Ag and Cu nanoparticles against Trametes versicolor white-rot fungus. Wood Mater Sci Eng:1–8. https://doi.org/10.1080/1748027 2.2021.1977996 Prakash Sharma V, Sharma U, Chattopadhyay M, Shukla VN (2018) Advance applications of nanomaterials: a review. Mater Today Proc 5:6376–6380 Rabajczyk A, Zielecka M, Popielarczyk T, Sowa T (2021) Nanotechnology in fire protection -application and requirements. Materials 14:7849 Rahayu I, Darmawan W, Zaini LH, Prihatini E (2020) Characteristics of fast-growing wood impregnated with nanoparticles. J For Res 31:677–685

Nanomaterials to Improve Fire Properties in Wood and Wood-Based Composite Panels

93

Rajan R, Näkki J, Layek R, Rainosalo E (2021) Wood plastic composites with improved electrical and thermal conductivity. Wood Sci Technol 55:719–739 Raji M, Mekhzoum MEM, Rodrigue D, Bouhfid R (2018) Effect of silane functionalization on properties of polypropylene/clay nanocomposites. Compos Part B-Eng 146:106–115 Rana HT, Gupta RK, GangaRao HV, Sridhar LN (2005) Measurement of moisture diffusivity through layered-silicate nanocomposites. AICHE J 51:3249–3256 Rangavar H, Nourbakhsh A, Haji Hatmlo S (2016) The effect of nano-wollastonite on physical and mechanical properties of wood plastic composites made with sunflower stem waste and alder. Iran J Wood Paper Sci Res 31:684–694 Rassam GH, Taghiyari HR, Jamnani B, Khaje MA (2010) Effect of nano-silver treatment on densified wood properties. Part one: swelling, recovery set, bending strength. In: 41st Annual Meeting of the International Research Group on Wood Protection, Biarritz, France, 9–13 May 2010. IRG Secretariat Roumeli E, Papadopoulou E, Pavlidou E, Vourlias G, Bikiaris D, Paraskevopoulos KM, Chrissafis K (2012) Synthesis, characterization and thermal analysis of urea–formaldehyde/nanoSiO2 resins. Thermochim Acta 527:33–39 Salari A, Tabarsa T, Khazaeian A, Saraeian A (2013) Improving some of applied properties of oriented strand board (OSB) made from underutilized low quality paulownia (Paulownia fortunie) wood employing nano-SiO2. Ind Crop Prod 42:1–9 Salma U, Chen N, Richter DL, Filson PB, Dawson-Andoh B, Matuana L, Heiden P (2010) Amphiphilic core/shell nanoparticles to reduce biocide leaching from treated wood, 1–leaching and biological efficacy. Macromol Mater Eng 295:442–450 Schirp A, Schwarz B (2021) Influence of compounding conditions, treatment of wood particles with fire-retardants and artificial weathering on properties of wood-polymer composites for façade applications. Eur J Wood Wood Prod 79:821–840 Sedliacik J, Bekhta P, Potapova O (2010) Technology of low-temperature production of plywood bonded with modified phenol-formaldehyde resin. Wood Res 55:123–130 Sengul AB, Asmatulu E (2020) Toxicity of metal and metal oxide nanoparticles: a review. Environ Chem Lett 18:1659–1683 Seo J, Cha J, Kim S, Kim S, Huh W (2014) Development of the thermal performance of wood-­ flooring by improving the thermal conductivity of plywood. J Biobased Mater Bioenergy 8:170–174 Seo HJ, Hwang W, Lee MC (2017) Fire properties of Pinus densiflora utilizing fire-retardant chemicals based on borated and phosphorus (I)–combustion characteristics. BioRes 12:5417–5427 Sharma V, Goyat MS, Hooda A, Pandey JK, Kumar A, Gupta R, Upadhyay AK, Prakash R, Kirabira JB, Mandal P, Bhargav PK (2020) Recent progress in nano-oxides and CNTs based corrosion resistant superhydrophobic coatings: A critical review. Prog Org Coat 140:105512 Shenoy AV, Saini DR (1986) Wollastonite reinforced polypropylene composites: dynamic and steady state melt flow behaviour. J Reinf Plast Comp 5:62–73 Sheshmani S, Ashori A, Fashapoyeh MA (2013) Wood plastic composite using graphene nanoplatelets. Int J Biol Macromol 58:1–6 Shi J, Li J, Zhou W, Zhang D (2007) Improvement of wood properties by urea-formaldehyde resin and nano-SiO2. Front For China 2:104–109 Soltani A, Hosseinpourpia R, Adamopoulos S, Taghiyari HR, Ghaffari E (2016) Effects of heat-­ treatment and nano-wollastonite impregnation on fire properties of solid wood. Bioresources 11:8953–8967 Song P-A, Yang H-T, Fu SY, Wu Q, Ye JW, Lu FZ, Jin YM (2011) Effect of carbon nanotubes on the mechanical properties of polypropylene/wood flour composites: reinforcement mechanism. J Macromol Sci B 50:907–921 Song K, Ganguly I, Eastin I, Dichiara A (2020) High temperature and fire behavior of hydrothermally modified wood impregnated with carbon nanomaterials. J Hazard Mater 384:121283 Suárez M, García-Romero E (2012) Variability of the surface properties of sepiolite. Appl Clay Sci 67:72–82

94

J. Kawalerczyk et al.

Taghiyari HR (2011) Study on the effect of nano-silver impregnation on mechanical properties of heat-treated Populus nigra. Wood Sci Technol 45:399–404 Taghiyari HR (2012) Fire-retarding properties of nano-silver in solid woods. Wood Sci Technol 46:939–952 Taghiyari HR, Farajpour Bibalan O (2013) Effect of copper nanoparticles on permeability, physical, and mechanical properties of particleboard. Eur J Wood Wood Prod 71:69–77 Taghiyari HR, Nouri P (2015) Effects of nano-wollastonite on physical and mechanical properties of medium-density fiberboard. Maderas-Cienc Tecnol 17:833–842 Taghiyari HR, Sarvari Samadi Y (2016) Effects of wollastonite nanofibers on fluid flow in medium-­ density fiberboard. J For Res 27:209–217 Taghiyari HR, Karimi A, Tahir PM (2013a) Nano-wollastonite in particleboard: physical and mechanical properties. Bioresources 8:5721–5732 Taghiyari HR, Mobini K, Sarvari-Samadi Y et al (2013b) Effects of nano-wollastonite on thermal conductivity coefficient of medium-density fiberboard. J Nanomater Mol Nanotechnol 2(1). https://doi.org/10.4172/2324-­8777.1000106 Taghiyari HR, Rangavar H, Nouri P (2013c) Fire-retarding properties of nanowollastonite in MDF. Eur J Wood Wood Prod 71:573–581 Taghiyari HR, Majidi R, Jahangiri A (2016a) Adsorption of nanowollastonite on cellulose surface: effects on physical and mechanical properties of medium-density fiberboard (MDF). Cerne 22:215–222 Taghiyari HR, Mohammad-Panah B, Morrell JJ (2016b) Effects of wollastonite on the properties of medium-density fiberboard (MDF) made from wood fibers and camel-thorn. Maderas-Cienc Tecnol 18:157–166 Taghiyari HR, Hosseinpourpia R, Adamopoulos S, Jahangiri A, Rabie D (2017a) Effects of nano-wollastonite impregnation on fire properties of some thermally-treated solid wood species. In: IRG48 Scientific Conference on Wood Protection, Ghent, Belgium, 4–8 June 2017. International Research Group on Wood Protection Taghiyari HR, Norton J, Tajvidi M (2017b) Effects of nano-materials on different properties of wood-composite materials. In: Bio-based wood adhesives: preparation, characterization, and testing. CRC Press, pp 310–339 Taghiyari HR, Kalantari A, Kalantari A, Avramidis S (2019) Effect of wollastonite nanofibers and exposure to Aspergillus niger fungus on air flow rate in paper. Measurement 136:307–313 Taghiyari HR, Hosseini SB, Ghahri S, Ghofrani M, Papadopoulos AN (2020a) Formaldehyde emission in micron-sized wollastonite-treated plywood bonded with soy flour and urea-­ formaldehyde resin. Appl Sci 10:6709 Taghiyari HR, Soltani A, Esmailpour A, Hassani V, Gholipour H, Papadopoulos AN (2020b) Improving thermal conductivity coefficient in oriented strand lumber (OSL) using sepiolite. Nano 10:599 Taghiyari HR, Tajvidi M, Taghiyari R, Mantanis GI, Esmailpour A, Hosseinpourpia R (2020c) Nanotechnology for wood quality improvement and protection. In: Nanomaterials for agriculture and forestry applications. Elsevier, pp 469–489 Taghiyari HR, Militz H, Antov P, Papadopoulos AN (2021a) Effects of wollastonite on fire properties of particleboard made from wood and chicken feather fibers. Coatings 11:518 Taghiyari HR, Tajvidi M, Soltani A, Esmailpour A, Khodadoosti G, Jafarzadeh H, Militz H, Papadopoulos AN (2021b) Improving fire retardancy of unheated and heat-treated fir wood by nano-sepiolite. Eur J Wood Wood Prod 79:841–849 Teng T-J, Arip MNM, Sudesh K, Nemoikina A, Jalaludin Z, Ng EP, Lee HL (2018) Conventional technology and nanotechnology in wood preservation: a review. BioRes 13:9220–9252 Terzi E, Kartal SN, Yılgör N, Rautkari L, Yoshimura T (2016) Role of various nano-particles in prevention of fungal decay, mold growth and termite attack in wood, and their effect on weathering properties and water repellency. Int Biodeterior Biodegradation 107:77–87 Thomas A, Moinuddin K, Zhu H, Joseph P (2021) Passive fire protection of wood using some bio-­ derived fire retardants. Fire Safety J 120:103074

Nanomaterials to Improve Fire Properties in Wood and Wood-Based Composite Panels

95

Tichi AH, Bazyar B, Khademieslan H, Rangavar H, Taleipour M (2016) The effect of nano-­ wollastonite on biological, mechanical, physical and microstructural properties of the composite made of wood-cement fiber. Int J Fundam Appl 8:1466–1479 Tichi AH, Bazyar B, Khademieslam H, Rangavar H, Talaeipour M (2019) Is wollastonite capable of improving the properties of wood fiber-cement composite? Bioresources 14:6168–6178 Treusch O, Hofenauer A, Tröger F, Fromm J, Wegener G (2004) Basic properties of specific wood-­ based materials carbonised in a nitrogen atmosphere. Wood Sci Technol 38:323–333 Uddin I, Poddar P, Kumar U, Phogat N (2013) A novel microbial bio-milling technique for the size reduction of micron sized Gd2O3 particles into nanosized particles. J Green Sci Technol 1:48–53 Ullah S, Ahmad F, Shariff AM, Raza MR, Masset PJ (2017) The role of multi-wall carbon nanotubes in char strength of epoxy based intumescent fire retardant coating. J Anal Appl Pyrolysis 124:149–160 Wan C, Jiao Y, Li J (2015) In situ deposition of graphene nanosheets on wood surface by one-pot hydrothermal method for enhanced UV-resistant ability. Appl Surf Sci 347:891–897 Wang F, Wang Q, Wang X (2010a) Progress in research on fire retardant–treated wood and wood-­ based composites: a Chinese perspective. Forest Prod J 60:668–678 Wang Z, Han E, Liu F, Ke W (2010b) Fire and corrosion resistances of intumescent nano-coating containing nano-SiO2 in salt spray condition. J Mater Sci Technol 26:75–81 Wang W, Zhu Y, Cao J, Liu R (2014) Improvement of dimensional stability of wood by in situ synthesis of organo-montmorillonite: preparation and properties of modified Southern pine wood. Holzforschung 68:29–36 Wang X, Kalali EN, Wan J-T, Wang D-Y (2017) Carbon-family materials for flame retardant polymeric materials. Prog Polym Sci 69:22–46 Wang H, Zhang X, Guo S, Liu T (2021) A review of coextruded wood–plastic composites. Polym Compos 42:4174–4186 Waychunas GA, Zhang H (2008) Structure, chemistry, and properties of mineral nanoparticles. Elements 4:381–387 Wieruszewski M, Lis W, Mirski R (2015) A qualitative and dimensional characterisation of round wood vs sawmill costs. Intercathedra 1(31):97–104 Wong JF, Chan JX, Hassan AB (2021) Thermal and flammability properties of wollastonite-filled thermoplastic composites: a review. J Mater Sci 56:8911–8950 Wu L, Liao L, Lv G (2015) Influence of interlayer cations on organic intercalation of montmorillonite. J Colloid Interf Sci 454:1–7 Wu Q, Miao W, Gao H, Hui D (2020) Mechanical properties of nanomaterials: a review. Nanotechnol Rev 9:259–273 Xu Q, Chen L, Harries KA, Zhang F, Liu Q, Feng J (2015) Combustion and charring properties of five common constructional wood species from cone calorimeter tests. Constr Build Mater 96:416–427 Xu Z, Liu D, Yan L, Xie X (2020a) Synergistic effect of sepiolite and polyphosphate ester on the fire protection and smoke suppression properties of an amino transparent fire-retardant coating. Prog Org Coat 141:105572 Xu Z, Zhou H, Yan L, Jia H (2020b) Comparative study of the fire protection performance and thermal stability of intumescent fire-retardant coatings filled with three types of clay nano-­ fillers. Fire Mater 44:112–120 Xue F, Zhao G (2008) Optimum preparation technology for Chinese fir wood/Ca-montmorillonite (Ca-MMT) composite board. For Stud China 10:199–204 Xue Q, Sun W, Fagerstedt K, Guo X, Dong M, Wang W, Cao H (2018) Effects of wood rays on the shrinkage of wood during the drying process. Bioresources 13(3):7086–7095 Yadav R (2021) Development of low formaldehyde emitting particle board by nano particle reinforcement. J Appl Nat Sci 13:1187–1197

96

J. Kawalerczyk et al.

Yaghoobi H, Fereidoon A (2018) Evaluation of viscoelastic, thermal, morphological, and biodegradation properties of polypropylene nano-biocomposites using natural fiber and multi-walled carbon nanotubes. Polym Compos 39:E592–E600 Yamanaka S, Magara K, Hirabayashi Y, Fujimoto T, Kuga Y (2017) Reduction of formaldehyde emission from plywood using composite resin composed of resorcinol–formaldehyde and urea-modified scallop shell nanoparticles. Wood Sci Technol 51:297–308 Yan Q-L, Gozin M, Zhao FQ, Cohen A, Pang SP (2016) Highly energetic compositions based on functionalized carbon nanomaterials. Nanoscale 8:4799–4851 Yan L, Xu Z, Wang X (2017) Influence of nano-silica on the flame retardancy and smoke suppression properties of transparent intumescent fire-retardant coatings. Prog Org Coat 112:319–329 Yan L, Xu Z, Wang X (2018) Synergistic effects of organically modified montmorillonite on the flame-retardant and smoke suppression properties of transparent intumescent fire-retardant coatings. Prog Org Coat 122:107–118 Yang F, Wu Y, Zhang S, Zhang H, Zhao S, Zhang J, Fei B (2020) Mechanical and thermal properties of waterborne polyurethane coating modified through one-step cellulose nanocrystals/ graphene materials sols method. Coatings 10:40 Ye X, Wang H, Tian X, Zhang Y (2019) Potential features of a 3D compatible polyethyleneimine-­ graphene oxide interface in WPCs via nano-self-assembly-modification. Polym Compos 40:3233–3241 Yu Y, Qi S, Zhan J, Wu Z, Yang X, Wu D (2011) Polyimide/sepiolite nanocomposite films: preparation, morphology and properties. Mater Res Bull 46:1593–1599 Yu G, Bu Q, Cao Z, Du X, Xia J, Wu M, Huang J (2016) Brominated flame retardants (BFRs): a review on environmental contamination in China. Chemosphere 150:479–490 Zhang H, Zhang W, Jin C, Li S (2016a) Inorganic antiflaming wood caused by a-decorated ZnO nanorod arrays coating prepared by a facile hydrothermal method. J Nanomater 2016. https:// doi.org/10.1155/2016/2358276 Zhang S, Chen Z, Xu Z, Gang S, Bai H, Liu X (2016b) Hydrophobic, transparent waterborne UV-curable polyurethane nanocomposites based on polycarbonate and PCL-PDMS-PCL reinforced with colloidal silica. J Coat Technol Res 13:1021–1033 Zhang P, Wan J, Wang K, Li Q (2017) Influence of nano-SiO2 on properties of fresh and hardened high performance concrete: a state-of-the-art review. Constr Build Mater 148:648–658 Zhang X, Hao X, Hao J, Wang Q (2018) Thermal and mechanical properties of wood-plastic composites filled with multiwalled carbon nanotubes. J Appl Polym Sci 135:46308 Zhang X, Zhang J, Wang R (2019) Thermal and mechanical behavior of wood plastic composites by addition of graphene nanoplatelets. Polymers 11:1365 Zhang L, Xu J, Shen H, Xu J, Cao J (2021) Montmorillonite-catalyzed furfurylated wood for flame retardancy. Fire Saf J 121:103297 Zhao J, Shao Q, Ge S, Zhang J, Lin J, Cao D, Wu S, Dong M, Guo Z (2020) Advances in template prepared nano-oxides and their applications: polluted water treatment, energy, sensing and biomedical drug delivery. Chem Rec 20:710–729 Zheng Y, Zheng Y (2006) Study on sepiolite-reinforced polymeric nanocomposites. J Appl Polym Sci 99:2163–2166 Zhou L, Fu Y (2020) Flame-retardant wood composites based on immobilizing with chitosan/ sodium phytate/nano-TiO2-ZnO coatings via layer-by-layer self-assembly. Coatings 10:296 Zhou J, Tan Z, Liu Z, Jing M, Liu W, Fu W (2017) Preparation of transparent fluorocarbon/TiO2-­ SiO2 composite coating with improved self-cleaning performance and anti-aging property. Appl Surf Sci 396:161–168 Zhuang C, Chen Y (2019) The effect of nano-SiO2 on concrete properties: a review. Nanotechnol Rev 8:562–572

Wood Plastic Composites (WPCs): Applications of Nanomaterials Mustafa Zor, Fatih Mengeloğlu, Deniz Aydemir, Ferhat Şen, Engin Kocatürk, Zeki Candan, and Orhan Ozcelik

Contents 1  I ntroduction 2  A  n Overview of Wood Plastic Composite Technology and the Latest Developments in Wood Plastic Composites 3  Nanomaterial Reinforcements Used in Wood Plastic Composites 3.1  The Effects of Nano-fillers on the Physical Properties and Durability of the WPCs

 98  100  101  102

M. Zor (*) Department of Forestry, Zonguldak Bulent Ecevit University, Zonguldak, Turkey Biomaterials and Nanotechnology Research Group & NanoTeam, Istanbul, Turkey e-mail: [email protected] F. Mengeloğlu Department of Forest Industrial Engineering, Kahramanmaraş Sütçü İmam University, Avşar, Turkey D. Aydemir Department of Forest Industrial Engineering, Bartın University, Bartın, Turkey F. Şen Department of Food Proccesing, Zonguldak Bulent Ecevit University, Zonguldak, Turkey E. Kocatürk Biomaterials and Nanotechnology Research Group & NanoTeam, Istanbul, Turkey Department of Nanotechnology Engineering, Zonguldak Bulent Ecevit University, Zonguldak, Turkey Z. Candan Biomaterials and Nanotechnology Research Group & NanoTeam, Istanbul, Turkey Department of Forest Industrial Engineering, Istanbul University Cerrahpasa, Istanbul, Turkey O. Ozcelik Department of Aerospace Engineering, Ankara Yildirim Beyazit University, Ankara, Turkey © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 H. R. Taghiyari et al. (eds.), Emerging Nanomaterials, https://doi.org/10.1007/978-3-031-17378-3_4

97

98 3.2  The Effects of Nano-fillers on the Mechanical Properties of the WPCs 3.3  The Effects of Nano-fillers on the Thermal Properties of the WPCs 4  Lignocellulosic Nanocomposite Materials 4.1  Lignocellulosic Materials 4.2  Cellulose-Based Nanomaterials (CNMs) 4.3  Lignin and Hemicellulose-Based Nanomaterials 4.4  Application Areas of Lignocellulosic Nanomaterials 4.5  Lignocellulosic Nanomaterials as Reinforcements in Composites 5  Conclusion References

M. Zor et al.  104  107  108  108  109  111  113  117  120  120

1 Introduction Wood plastic composite (WPC) and thermoplastic polymers with lignocellulosic material as filler are referred to as a combination (Özmen et al. 2014). In other words, it can also be named as materials consisting of different types of materials or phases that are combined to obtain superior properties by ameliorating each other’s weaknesses (Mengeloglu and Karakus 2008). WPC is an important engineered material that uses wood powder among industrially important cellulosic filler reinforced plastic composites. WPCs, which were fully involved in the industry in the early 1990s, have a 30-year history of industrialization from recyclable plastics, including building materials (Gardner et al. 2015a, b; Watanabe 2012). First industrial applications of phenol were carried out with thermosetting resins such as formaldehyde. The use of thermoplastics began in the late 1960s, and today the popularity of WPCs, which are widely used in the industrial field, is rapidly increasing. It has found widespread use in outdoor environments, especially because its mechanical properties are relatively high compared with similar materials. These composite materials are highly resistant to humidity and environmental changes thanks to the hydrophobic polymers in their structures (Kaymakcı and Ayrılmış 2014; Özmen et al. 2014). Due to the increasing environmental concerns and health issues, natural fibers have received significant attention as alternative reinforcements in composites (Antov et al. 2020, 2021a, b; Taghiyari et al. 2020a, b; Savov et al. 2021). Natural fibers have higher strength-to-weight ratio compared with synthetic fibers. Compared with structures reinforced with glass fibers, the use of renewable fibers decreases the cost and weight by 5–10%, while reducing energy requirements by about 80%. The use of lignocellulosic waste wood materials and natural fibers has gained significant importance both in academy and industry (Hassanin et al. 2016; Merzoug et  al. 2020; Yildirim et  al. 2020). WPCs have attracted the attention of industry engineers due to their structural properties (El-Haggar and Kamel 2011). Due to their high durability, low maintenance cost, low cost, and low biodegradation rate, the WPCs are especially preferred in outdoor applications (decking, fencing, floor coating, roof tiles, window joinery, garden furniture, auto parts, etc.) (Clemons and Caulfi 2005; Zor et al. 2016). Since WPCs are harder than plastic materials, they stand out as the advanced engineering materials with the highest performance

Wood Plastic Composites (WPCs): Applications of Nanomaterials

99

(Marutzky 2004; Bledzki et al. 2002; Riedel and Nickel 2003; Aydemir et al. 2014a, b, 2015a, b). However, the low production capacity, high energy costs, and high density compared with wooden materials are the main disadvantages of WPCs (Principia Partners 2002; Karakuş 2008). WPCs are generally produced in two stages. The raw materials that will form the composite material are mixed and combined homogeneously using a mixer. The resulting mixture goes through a second process. At this stage, the material is given its final shape by injection, extrusion, or pressure molding methods. Alternatively, the mixture obtained after the initial processing can be melted under heat and pressed into the shape of final product (Aslan 2008). Nano-sized fillers with a large surface area can significantly increase the interfacial interactions in the composite at the molecular level, leading to materials with novel properties. The production of WPCs has been termed “green technology” because of the possibility of using the recycled plastic and waste wood. However, the primary issue in the production of WPCs is that the hygroscopic wood is not naturally compatible with the hydrophobic polymer matrix. Incompatible matrix reinforcement interface inevitably results in poor mechanical properties in the fabricated composite material (Turku and Karki 2014). Properties such as low cost, low density, high strength, low abrasion, and biodegradability of lignocellulosic fibers make their use attractive in the production of WPCs (Chen 2009). Lignocellulosic biomass consists of nanometer-sized particles and blocks that add value to wood or other renewable lignocellulosic materials. These building blocks owe their high strength and optical properties to the nanoscale miracle of their structures (Sarikaya et al. 2003). On the other hand, nanostructured nature of cellulose, lignin, or their derivatives provide the advanced engineering materials (paper, cardboard, OSB, plywood, LVL, CLT, GLULAM, etc.) with high strength and stability (Klemm et al. 2005). For example, the paper material is an organic material produced from fibers that have been “pulped” and refined to release fibrils, microfibrils/nanofibrils, and nanocrystalline cellulose originating from the natural structure of wood (Brown et al. 1987). It can be seen that the relationship between nanotechnology and lignocellulosic biomass is rather weak. However, it is very important to understand the miracle that took place here. While the relative masses of nanofibrils and nanocrystalline cellulose are small, their surface areas increase with nanotechnology, and it is seen that they contribute to important application areas in the industry with their significant surface energies.

100

M. Zor et al.

2 An Overview of Wood Plastic Composite Technology and the Latest Developments in Wood Plastic Composites Wood plastic composite technology continues to mature with improvements being made in manufacturing processes (extrusion, injection, and compression molding); material advances in novel polymers matrices, treatments, and additives; profiles and parts for construction, automobiles, and furniture; durability from weather, fire, and biological attack; and the development of product standards for building construction. New developments are being made especially in the area of nano-­additives for WPCs including nano-cellulose. Patent activity in WPCs continues to increase with the development of new product types and market application areas (Gardner et al. 2015a, b). Since first introduced in the 1980s, the WPCs have a long, fulfilling, changing, and challenging adventure over the years. Changes in people’s perspectives and demands generated new and changing application potentials for WPC. Although WPCs were used mainly in decking applications when first introduced, nowadays, they are used in various applications from packaging to the automotive industry. The future seems even more promising as far as the utilization and development of the WPCs are considered. Prospects for the application areas of the WPCs are briefly discussed below. Thanks to the recent developments in the WPCs technology, they have become more eligible to be utilized in 3-D printing. Three-dimensional printing, also known as additive manufacturing (AM), rapid prototyping (RP), or solid-freeform (SFF), is a manufacturing technique, which is used to produce parts through the deposition of raw material in multiple layers. Entire process requires an elaborate software that converts the 3-D computer-aided design (CAD) model of the part into a set of instructions used to control and direct the 3-D printer (Pervaiz et al. 2021). Fused deposition modeling (FDM) is a widely used 3-D printing process in which a thermoplastic filament is extruded through a heated orifice (die), thereby depositing a layer of polymer melt. The fact that wood is highly susceptible to thermal effects delayed its utilization in 3-D printing processes based on the FDM or other techniques employing a heat source. It is well known that the wood ingredients such as cellulose, hemicellulose, and lignin burn instead of melting when heated. Therefore, wood needs to be chemically or mechanically modified and/or blended with other materials to be utilized in 3-D printing (FDM or other AM processes employing heat). Commercial utilization of wood in 3-D printing applications is available for a limited number of polymers like polylactic acid (PLA) and co-polyesters (Brownell 2021). WPCs are subjected to several different environmental conditions during their life cycle. These environmental effects may induce physical, mechanical, or chemical damage in the WPCs. Quite often the adverse environmental effects reveal themselves as the cracks, splits, or discolorations on the surface of the WPCs. Studies showed that different additives might be used in the formulation of WPC to improve its durability (Chaochanchaikul and Sombatsompop 2011; Chaochanchaikul et al.

Wood Plastic Composites (WPCs): Applications of Nanomaterials

101

2011). On the other hand, coextrusion technology may effectively prevent these damages from occurring and offer novelties in the manufacturing of WPCs. In the coextrusion technique, a WPC is used as a core material, which is covered (shielded) by a shell (cap) layer made out of the same polymer as the WPC or a different one with improved formulation against environmental degradation. A number of research efforts showed that utilization of nano-carbon black and nano-TiO2 lessens the discoloration and reduces the amount of surface cracks on the WPCs. It was also reported that their synergistic effect retarded the photooxidative aging of PE-based WPCs (Wang et  al. 2017). Mengeloğlu and Çavuş (2021) also reported similar results for PP-based WPCs produced with micro- and nano-sized TiO2. It seems that the coextrusion technology utilizing shell layers with nanomaterial additives for protection against harsh environmental conditions has a great potential in future applications of the WPCs. Nowadays, recycling is a common issue encountered in the manufacturing of the WPCs. It is quite common, especially in North America, to use a recycled polymer or a recycled wood material, or both, in the manufacturing of the WPCs. The use of recycled material in the WPC manufacturing has recently become popular also in Europe. However, recovering a clean raw material with predictable homogeneous properties remains as a major challenge to achieve a recycled material. On the other hand, recycling the end-of-life WPCs is a daunting task that the sector has been facing over the years. Since, in general, the recyclate needs to be obtained from a waste stream containing a wide variety of WPC compositions, the selection of material, which is worth recycling, is a highly challenging task (Zhou et al. 2022). Obviously, further research needs to be done toward achieving effective and efficient recycling of the WPCs. Among the previously mentioned topics, the utilization of organic or inorganic nanomaterials in the WPCs has received considerable attention recently. In the following sections, the subjects of “Nanomaterial Reinforcements Used in Wood Plastic Composites” and “Lignocellulosic Nanocomposite Materials” will be discussed in detail.

3 Nanomaterial Reinforcements Used in Wood Plastic Composites Because of the inherently delicate structures of the natural lignocellulosic materials, achieving high mechanical properties and maintaining structural stability in the wood polymer composites (WPCs) are known to be very challenging in many application areas (Taghiyari 2014; Taghiyari et al. 2020b; Crowther et al. 2015; Cornwall 2016). Various additives including UV stabilizers or fillers including synthetic or natural fibers/particles, etc. have been used to improve mechanical properties, dimensional stability, and color stability for a long time (Taghiyari 2014; Taghiyari et  al. 2020b; Montanari et  al. 2021). Although WPCs have been used in many

102

M. Zor et al.

applications including construction panels, indoor/outdoor deck flooring, outdoor furniture, landscaping applications, etc., the technological development of the WPCs has not fully utilized the advantages of nanotechnology to broaden the application spectrum. Nano-fillers are the particles having at least one dimension in the nanometer range, i.e., roughly 1–100  nm. When incorporated into the polymer matrix domain of the traditional composites, the nano-fillers can significantly improve the properties such as structural durability, dimensional stability, strength, stiffness, toughness, and thermal stability, while enabling to produce environmentally friendly composite materials with reduced toxic reactants and low CO2 emissions (Candan 2012; Candan and Akbulut 2013, 2014, 2015; Montanari et al. 2021; Ramesh et al. 2022). Since the nano-fillers have very high surface-to-volume and aspect ratios, they are capable of establishing strong contact with the polymer matrix at the molecular level through an ultralarge interfacial area. The strong molecular interaction between the nano-filler and the polymer matrix is known to be responsible for the improved properties that traditional composites do not possess (Guz 2012; Li 2012; Drobny 2014; Koo 2006). Therefore, the use reinforcing nanofillers has also received great attention in the research field of WPCs (Aydemir et al. 2015; Sözen et al. 2018). Over the last decade, there have been a significant number of research efforts aiming at improving the mechanical, physical, and thermal properties of WPCs by using the nano-fillers, as depicted in Fig.  1. We will summarize these research efforts in the following three subsections, which focus on the effects of nano-fillers on the physical, mechanical, and thermal properties of the WPCs, respectively.

3.1 The Effects of Nano-fillers on the Physical Properties and Durability of the WPCs WPCs are commonly used in outdoor applications, which include residential deck boards, window and door frames, and garden furniture, to name but a few. To withstand adverse environmental effects (i.e., high temperature, humidity, and ultraviolet radiation), the WPCs should possess high physical properties and durability. The previous studies show that the reinforcing nano-fillers generally led to significant improvements in the physical properties and durability of WPCs due to strong interaction between the polymer matrix and the nano-filler (Cai et  al. 2010; Ismaeilimoghadam et al. 2016; Ghalehno et al. 2020). Devi and Maji (2012) studied UV stability and some physical properties of the WPCs with the reinforcement of nano-ZnO.  The addition of ZnO to the WPCs resulted in improved dimensional stability, water resistance, and UV stability, which were attributed to good dispersion of nanoparticles in the WPCs at the molecular level. Several researchers have reported that the ZnO nanoparticles improved the photostability, UV stability, and outdoor performance of WPCs (Yu et  al. 2010; Weichelt et al. 2010).

Wood Plastic Composites (WPCs): Applications of Nanomaterials

103

Fig. 1  Scientific papers related to WPCs with nano-fillers published in SCI-indexed journals. (Source: Web of Science)

Ghalehno et al. (2020) studied the effects of nano-TiO2 on the physical properties and UV stability of the WPCs, and their results showed that the incorporation of nano-TiO2 resulted in improvements in the dimensional stability, water absorption, and UV stabilization. The improved UV stabilization was attributed to high refractive index and ultraviolet filtration capacity of the TiO2 nanoparticles. Similar results have been reported in a number of articles focusing on the effects of nano-TiO2 particles on the properties of WPCs (Hayle and Gonfa 2014; Prasad et  al. 2018; Wang et al. 2019, 2020). Yadav and Yusoh (2015) studied the effects of nanoclays on the physical properties of the WPCs. The results showed that the addition of nanoclay decreased the water uptake of the composite by as much as 13%, which was obtained at the loading of 3.5 wt. %. Dimensional stability, water absorption, flame retardation, water vapor resistance, fungal resistance, and UV stability of the WPCs were found to increase linearly with the addition of clay, SiO2, and ZnO by Deka et al. (2012), Morrell and Silva Guzman (2006), Devi and Maji (2007), and Kaymakci (2020). Bari et al. (2015) investigated the effects of nanoclay on the biological durability of WPCs against five wood-deteriorating fungi. The addition of nanoclays yielded an improvement in the biological properties of the WPCs. The improvements were

104

M. Zor et al.

found to vary in magnitude depending on the fungi species. At the nanoclay content of 6%, and the highest (3.2%) and lowest (0.2%) mass losses were produced by Trametes versicolor and Physisporinu vitreus, respectively. Although weight losses were extremely low, nanoclay considerably inhibited the growth of wood-­ deteriorating fungi. Mass loss was determined to correlate with water absorption. Similar results were found by DePolo and Baird 2009 and Haghighi Poshtiri et al. (2013). In summary, the studies show that since the polymer constituent of the WPCs are generally resistant to biological attacks and water degradation, it is the wood constituent that needs to be treated for improved durability and dimensional stability. The literature review shows that the nano-filler reinforcements have many advantages to improve the physical properties and durability of the WPCs.

3.2 The Effects of Nano-fillers on the Mechanical Properties of the WPCs The WPCs are the engineering composite materials that have been commonly used in the applications of transportation, load-bearing outdoor structures, and building construction. Although their usage has increased steadily over the past decade and they have gradually replaced the conventional wood-based panels, their use is still quite limited to the abovementioned applications. To broaden the application areas of the WPCs, their mechanical properties must be improved. For this purpose, various types of nano-fillers at different loading levels have been tested in many research efforts (Mondal 2018; Ghalehno et  al. 2020). Difficulty in obtaining a well-dispersed nano-filler in the matrix domain has been a major obstacle to achieve improved mechanical properties. The addition of nano-fillers into the host matrix has been generally found to increase the elastic moduli and the strength of the composite. As their amount (wt %) is increased beyond a certain threshold, however, the nano-fillers start agglomerating rather than dispersing into the polymer matrix, resulting in loss of adhesion at the matrix-nano-filler interface and, thus, significant reductions in mechanical properties (Devi and Maji 2012; Ismaeilimoghadam et al. 2016; Mondal 2018; Ghalehno et al. 2020). In recent years, many research efforts have been carried out to investigate the effects of nano-fillers on the mechanical properties of WPCs. Ismaeilimoghadam et al. (2016) investigated the effects of nano-TiO2 and nano-SiO2 on the mechanical properties of WPCs. The effect of nano-fillers on mechanical properties is shown in Fig. 2. Their results showed that the composites containing nano-SiO2 resulted in more favorable bending and tensile properties (strength and modulus) compared with those containing nano-TiO2. While increasing the nanoparticles from 0 to 3 wt % led to an increase in tensile strength, the addition of more nanoparticles up to 5 wt % resulted in a significant decrease in tensile strength, which was attributed to aggregation of the nanoparticles on the composite substrate, as shown in Fig. 3b.

Wood Plastic Composites (WPCs): Applications of Nanomaterials

105

Fig. 2  The effects of the nano-fillers on the mechanical properties (Ismaeilimoghadam et al. 2015)

Deka and Maji (2012) examined the effects of nano-fillers including silica and nanoclay on the mechanical properties of WPCs. The results showed that adding both nano-filler at a loading rate of 3% increased flexural and tensile strength, as well as flexural and tensile moduli. However, when the loading rate was increased from 3% to 5%, the mechanical properties decreased because of the agglomeration of the nano-fillers in the polymer matrix. Similar findings were obtained in a number of studies conducted with SiO2, TiO2, or nanoclays (Altan and Yildirim 2010; Ashori 2013; Kord and Taghizadeh Haratbar 2016; Ismaeilimoghadam et al. 2015; Kaymakci 2020). Devi and Maji (2012) prepared a WPC via impregnation of styrene-acrylonitrile polymer (SAN) and ZnO nanoparticles into Simul wood (Bombax ceiba L.). They studied the effect of nano-ZiO on the tensile and flexural properties of the WPC. The results indicated that the addition of ZnO nanoparticles at the loadings of 0.2 and 5% increased both strength and modulus of the WPC specimens tested for bending and tensile properties. On the other hand, several studies showed that natural nanofibers and nanoparticles can be used to improve the mechanical properties of WPCs. Li et al. (2014a, b) added cellulose nanofibers (CNFs) synthesized from poplar flour into the matrix of

106

M. Zor et al.

Fig. 3  The good dispersion and aggregation of the nano-fillers on the mechanical properties (Mondal 2018)

high-density polyethylene (HDPE) and wood flour. Maleic anhydride-grafted polyethylene (MAPE) was used as the coupling agent to improve the interfacial bonding. They were able to obtain well-dispersed ultralong CNFs in the WPC; as a result, the bending strength, bending modulus, and impact strength of the WPCs with 20 wt% CNF increased by 93, 154, and 117%, respectively, compared with WPC without CNF.  The results revealed that natural nanofibers can be used as a costeffective alternative to the synthetic nanofibers in the WPCs. Nikmatin et al. (2017) studied the effect of natural rattan (classified under the palm family, Palmae or Arecaceae) nanoparticles on mechanical properties of polypropylene (PP) composites. The coupling agent maleic anhydride (MA) was used to improve the interfacial adhesion between the hydrophilic natural nano-fillers (rattan) and the hydrophobic polymer matrix PP. Their results indicated that natural nanoparticles, when treated properly for interfacial adhesion, can improve the mechanical properties of polymer composites at the same level as the improvement achieved by using the glass fibers. These studies show that adhesion at the interface of the nano-fillers and the matrix can be improved by using coupling agents such as maleic anhydride or silane. It can be concluded that the mechanical properties of WPCs can be improved significantly through the use of nano-fillers as reinforcements provided that the nano-fillers are dispersed well in the matrix domain.

Wood Plastic Composites (WPCs): Applications of Nanomaterials

107

3.3 The Effects of Nano-fillers on the Thermal Properties of the WPCs Besides fire, which is known to be a major threat to wood and wood-based materials, time-varying thermal effects of the environment degrade the structural integrity and dimensional stability of WPCs in many applications (e.g., decking, fencing, building construction, garden furniture, and automotive industry). Therefore, in recent years, many research efforts have been devoted to improve the thermal properties of the WPCs by using nanoparticles. Ndiaye et al. (2013) studied the effect of nanoclay on the thermal behavior of polypropylene-based WPCs. The results obtained from a differential scanning calorimetry (DSC) showed that adding nanoclay increased both the melting temperature (Tm) and the crystallization temperature (Tc) of the WPC, compared with those of WPC without nanoclay. Zhong et al. (2007) studied the effect of nanoclay content on the heat deflection temperature (HDT) and thermal expansion coefficient (TEC) of polyethylene-based WPCs. As the nanoclay content was increased from 0 to 3 wt %, the HDT increased by 10 °C, and the TEC decreased by as much as 60%, compared with the WPC without clay. Increasing the clay content from 3 to 5 wt % did not reveal any change in the HDT, whereas it slightly increased the value of TEC. The slight increase in the TEC was explained as a harbinger of possible clay dispersion limit for the same compatibilizer content. Besides nanoclay, nanoparticles of titanium and boron compounds were considered in a number of recent studies (Sözen et al. 2018; Al et al. 2018; Karakuş et al. 2017). Sözen et al. (2018) investigated the effects nano-titanium dioxide (TiO2) and nano-boron nitride (BN) on the thermal stability of polypropylene-based WPCs. Thermogravimetric analyses (TG and derivative-TG) showed that nanoparticle-­ reinforced WPCs did not reveal any significant difference when melting and degradation temperatures are considered. The TG/DTG results gathered from the nanoparticle-reinforced WPCs were found to be slightly less than those of neat polypropylene. Al et al. (2018) studied the effects of nano-boron nitride (NBN) on the thermal properties of polylactic acid (PLA) and polyhydroxybutyrate (PHB)-based WPCs. Thermogravimetric analyses showed that adding NBN generally improved the thermal stability of the WPCs, and, when the NBN loading rates are increased, the thermal stability of the WPCs generally increased. The degradation temperatures corresponding to the weight loss values of 10%, 50%, and 85% were found to increase with the filler loading rates. In derivative thermal gravimetry (DTG) curves, the maximum degradation temperature was determined to increase with the filler loading rates. The melting and crystallization temperatures, Tm and Tc, were found to increase with NBN loadings, whereas crystallinity (Xc) decreased with BN loadings in the PLA-based WPCs. Karakuş et al. (2017) found similar results change values for the WPCs with nano-boron nitride. The literature review shows that the thermal properties of the WPCs generally improve with the addition of nano-fillers into the matrix domain.

108

M. Zor et al.

4 Lignocellulosic Nanocomposite Materials 4.1 Lignocellulosic Materials Lignocellulosic biomaterials are popular raw materials used in the sustainable production of high value-added products (Ballesteros et  al. 2018). Lignocellulosic materials are the most abundant, natural, renewable, and biodegradable raw materials available for the development and maintenance of industrial societies, and thus, they play a critical role in the development of a sustainable global economy. Large quantities of lignocellulosic material are produced from many sources including lumber processes, pulp and paper production, industrial and household waste, and diverse agricultural processes (Iqbal et al. 2013). The properties such as low density, low cost, and energy consumption, being applicable to composite and nanocomposite manufacturing, being recyclable, and having reactive surfaces make the lignocellulosic materials preferable to synthetic materials. Today, there is an increase in the use of lignocellulosic biomass in advanced applications such as chemicals and advanced materials (Mohanty et al. 2002; Carmichael et al. 2020; Guo et al. 2020). Examples of lignocellulosic materials are shown in Fig. 4. Lignocellulosic biomass consists of nanoscale building blocks and provides valuable properties to lignocellulosic biomaterials, wood, and other cellulosic materials. Lignocellulosic nanomaterials derived from natural lignocellulosic biomass contain three main components: cellulose (35–50% by weight), lignin (5–30% by

Fig. 4  Examples of lignocellulosic materials (Anwar et al. 2014)

Wood Plastic Composites (WPCs): Applications of Nanomaterials

109

weight), and hemicellulose (20–35% by weight) (Kumar et  al. 2009; Iqbal et  al. 2011; Malherbe and Cloete 2002; Tozluoglu et al. 2017, 2018a, b). Cellulose is the main structural component of cell walls in plants and responsible for the mechanical strength. Cellulose, which has a fibrous structure, is a semicrystalline polymer. Its broad chain structure and microfibrillar morphology aid in its load-carrying capacity. It has a high molar mass and is inexpensive. It has the feature of being the most abundant biopolymer in the world (Olad et al. 2020; Wang et al. 2021; Calvo-Flores and Dobado 2010; Berglund 2005; Klemm et  al. 2011; Poyraz et  al. 2017a). Syringyl, guaiacyl, and p-hydroxyphenyl are the units of lignin, an aromatic polymer, while xylosyl, arabinosyl, glucuronosyl, glucopyranosyl, and acetyl groups are the units of hemicellulose, a branched polymer type (Kumar et al. 2017; Agustin et al. 2019). Hemicellulose, a cell-wall polysaccharide, is tightly bound to cellulose microfibers within the cell walls of plants (Liu et al. 2020, 2021; Carvalheiro et al. 2008). Lignocellulosic micro-/nanomaterial classification and chemical structures are shown in Fig. 5.

4.2 Cellulose-Based Nanomaterials (CNMs) Cellulose, a natural polymer produced by photosynthesis, is the main structural component of cell walls in all plants. Algae, fungi, bacteria, and invertebrates are other examples of living things that contain cellulose (Missoum et al. 2013; Khalil et al. 2014; Moon et al. 2011; Bayer et al. 2014; Raquez et al. 2013). The cellulose-­ based nanomaterials (CNMs) are the cellulose-containing materials with at least one dimension at the nanoscale. In other words, they are cellulose-based materials that have both crystalline and amorphous regions with diameters less than 100 nm, less than a few microns or equal lengths (Pennells et  al. 2020). Because of their

Fig. 5 Lignocellulosic micro-/nanomaterial classification and chemical structures (Wijaya et al. 2021)

110

M. Zor et al.

unique properties (e.g., high elastic modulus, low thermal expansion coefficient, dimensional stability, reinforcing potential, and transparency), the CNMs have received considerable attention recently (Hussin et  al. 2019). The CNMs can be classified according to their size and appearance, as shown in Fig. 6. Moreover, the CNMs can be classified into three categories based on the preparation methods and the raw materials: cellulose microfibrils (CMFs) or nanofibrils (CNFs), nanocrystalline cellulose (CNC), and bacterial nanocellulose (BNC) (Candan et  al. 2022; Foroughi et al. 2021; Li et al. 2013a, b; Kargarzadeh et al. 2018). Table 1 shows the classification of cellulosic nanomaterials according to preparation methods and raw materials. Meanwhile, it has been reported in the literature that different forms of nanocellulose are also produced (Salimi et  al. 2019; Trache et  al. 2017; Pires et al. 2019). Cellulose nanocrystals (CNCs) are a derivative of cellulose that can be obtained from wood, industrial waste biomass of abundant natural biopolymer, or agricultural waste; they often have a rod, needle, or spherical morphologies. CNC can be obtained by acid hydrolysis. The CNCs are composed of about 85% crystalline structure. The CNCs are biodegradable, biocompatible, and nontoxic materials with excellent surface charge and mechanical properties. These merits make the CNCs potentially eligible for being used in many diverse application areas. In addition, it has been reported in the literature that CNC lignocellulosic material can be produced by treating with biological enzymes in addition to reagents such as tetramethyl-­ piperidin-1-oxyl (TEMPO) and ammonium persulfate (APS). Furthermore, the CNC can be obtained by enzymatic hydrolysis. Studies on modification and application areas for nanocellulose production have been reported in the literature (Park et  al. 2019; Moohan et  al. 2020; Phanthong et  al. 2018; Shojaeiarani et al. 2019; He et al. 2019a; Tong et al. 2020; Kim et al. 2019; Miao

Fig. 6  Classification of CNMs by size and appearance (Foroughi et al. 2021)

Wood Plastic Composites (WPCs): Applications of Nanomaterials

111

Table 1  Classification of CNMs according to preparation methods and raw materials Nanocellulose type Cellulose nanocrystals (CNCs) Cellulose nanofibers (CNFs) Bacterial nanocellulose (BNC)

Description and dimensions Short rod-like shape/whiskers, varying from 5 to 70 nm in diameter to 100 to 250 nm in length A long fibril ranging from 5 to 60 nm in diameter to 500 nm to several μm in length Twisted strip/needle-shaped crystallites ranging in diameter from 20 to 100 nm to several μm in length

References Zhao et al. (2017), El-Samahy et al. (2017), Metreveli et al. (2014) Gopakumar et al. (2018), Tarrés et al. (2017), Hänninen et al. (2018) Xu et al. (2018), Millon et al. (2008), Kim et al. (2010)

and Hamad 2019; Poyraz et al. 2017b, 2018; Younas et al. 2019). Many different methods (e.g., mechanical treatment, enzymatic hydrolysis, chemical, acid hydrolysis, and oxidation methods) are used for the production of CNCs. CNCs are widely used in pharmaceutical products, civil engineering, food packaging, optical devices, plastics, coatings, additives, and catalysts (Prasanna and Mitra 2020; Calvino et al. 2020; Olad et al. 2020; Gao et al. 2020; Doh et al. 2020). Cellulose nanofibers (CNFs) are the nanoscale cellulose fibrils having both crystalline and amorphous regions. A typical CNF measures 5–60 nm in width and a few micrometers in length. The CNFs possess several features, which distinguish them from other materials. These features include superior mechanical properties, large surface area, and low density. CNFs are produced via mechanical and chemical methods. CNF production is possible by applying homogenization and ultrasonication from grinding materials such as cotton, wood, and fiber. Of these, homogenization is the most commonly known method for the CNF production (Hoeng et al. 2016; Siró and Plackett 2010; Habibi et al. 2010; Zhu et al. 2016; Lavoine et al. 2012; Moon et al. 2011). Different methods used in the production of CNFs and CNCs are illustrated in Fig. 7.

4.3 Lignin and Hemicellulose-Based Nanomaterials Lignin nanoparticles (LNPs), a lignin-derived biopolymer, form nano-sized structured aggregations. LNPs are polymers that exhibit both hydrophilic and hydrophobic properties, as well as negative surface charges. Lignin nanoparticles are not soluble in water. The outstanding properties of lignin nanoparticles are their biocompatibility, renewability, sustainability, and biodegradability. LNPs can be synthesized via various methods, which depend on the parameters used and on the further application of the LNPs. Ultrasonication, homogenization, acid precipitation, solvent shifting, and direct dialysis are some of the synthesis methods used in the production of LNPs (Alqahtani et al. 2020; Beisl et al. 2020; Agustin et al. 2019; Dai et al. 2017; Chen et al. 2020; Bertolo et al. 2019). The increase in the number of articles and patents related to the conversion of macro-lignin into lignin

112

M. Zor et al.

Fig. 7  CNC and CNF production in different ways (Rajinipriya et al. 2018)

nanoparticles (LNPs) in recent years is worth noting (Kai et al. 2016). LNPs with different morphologies (smooth colloidal, hollow, spherical, and hemispherical) have been successfully synthesized (Kumar et al. 2018, 2019; Fu et al. 2019). The synthesis of LNPs is simple and controllable and allows for the production of nanoparticles of different morphologies (Tian et al. 2017a). When the LNPs were first introduced to the market, the dialysis and acid precipitation methods were the only ones known for the production of LNPs. New methods have been developed

Wood Plastic Composites (WPCs): Applications of Nanomaterials

113

for the production of LNPs over the last decade. These methods include antisolvent precipitation, solvent exchange, ultrasonication, interfacial cross-linking, polymerization, and biological methods (Kim et al. 2013; Lievonen et al. 2016; Figueiredo et al. 2018; Chauhan 2020; Frangville et al. 2012; Jiang et al. 2013; Kumar et al. 2017; Yiamsawas et al. 2014; Rangan et al. 2017). Hemicellulose is the second most abundant polymer in the world. It is the second of the vital components in wood. By weight, 20–35% of dry wood is hemicellulose. Xylan is a basic type of hemicellulose. There are several techniques used in the production of nanohemicellulose. Studies suggest different ways to synthesize nanohemicellulose particles, including the use of nanocellulose-metal nanocomposites in addition to metallic, metal oxide, and carbon nanoparticles. Nanohemicelluloses reveal very interesting properties such as the possibility of separation by chromatography, drug release, and dynamic compound formulation. In the studies, xylan nanoparticles (XNPs) were produced by using corncob and wheat straw powder. XNPs play an active role in the development of target drug carriers in pharmacology. The XNPs are known for their biodegradability, biocompatibility, nontoxicity, and high fracture resistance. These outstanding properties allow them to be used as additives (in the manufacturing of textiles), drug carriers, adhesives, thickeners (in wound dressings), emulsifiers, stabilizers, and magnetite particle carriers. The most common methods used in the synthesis of XNPs are the precipitation and dialysis. Supercritical antisolvent micronization and dissolution of xyloglucans in dimethyl sulfoxide, acetone, and emulsions are among the other methods used in nanohemicellulose production (Terrett and Dupree 2019; Fu et al. 2019; Ghofrani-Isfahani et al. 2020; Li et al. 2013a, b; Yoo et al. 2012; Habibi and Lucia 2012; Oun et al. 2020; Lin et al. 2016; Perez et al. 2018; Kumar and Negi 2012; Daus and Heinze 2010; Kumar et al. 2018). Usage areas of lignocellulosic nanomaterials are shown in Fig. 8.

4.4 Application Areas of Lignocellulosic Nanomaterials Lignocellulosic nanomaterials are widely used in electronics, food coatings, batteries, supercapacitors, textiles, adhesives, biomedical applications, and cosmetics. They are also used as additives in paper- and cement-based products (Nurani et al. 2017; Lavoine et al. 2012; Maeda et al. 2006; Aulin and Ström 2013; Jeong et al. 2012; Carpenter et al. 2015; Plackett et al. 2014; Domingues et al. 2014; Song and Rojas 2013; Kojima et al. 2015; Lee and Oh 2013; Fornué et al. 2011; Klemm et al. 2011; Zhu et al. 2014; Markstedt et al. 2015; De Windt et al. 2014; Basu et al. 2017; Mertaniemi et  al. 2016). There is a high demand for recyclable and inexpensive green-energy storage devices. The lignocellulosic nanomaterials can be used in energy storage devices as an ideal material to meet these demands. It has been proposed to use a biodegradable lignocellulosic nanomaterial as an electrolyte material and an electrode binder in lithium-ion batteries (Jeong et al. 2012). In a study on batteries, a CNF network was placed around the graphite platelets as a binder to

114

M. Zor et al.

Fig. 8  Usage areas of lignocellulosic nanomaterials (Mokhena and John 2020)

improve the properties of the graphite anode (Jabbour et al. 2010). The resulting highly flexible electrodes had an electrochemical performance comparable with that of conventional electrodes. In another study, dispersed nanofibrillated cellulose was used as the electrode binder (Zolin et  al. 2014). The obtained bonding quality showed similar properties to commonly used polyvinylidene fluoride (PVDF) binder. Wang et al. (2015) fabricated a flexible Si-/CNT-/CNC-based anode, a triple system (nanocellulose, carbon nanotubes, and silicon nanoparticle). It was strongly coupled to the porous CNC-CNT matrix of Si particles. The resulting flexible battery comprised of a Si/CNT/CNC electrode was found to exhibit similar capacities and identical charge and discharge curves for both the flat and the bent configurations of the battery. The Si/CNT/CNC electrode was found to be a viable alternative for flexible battery systems. Jabbour et al. (2013) determined that the black CNF carbon with cellulose-based electrodes obtained by the filtration technique had a high elastic modulus. Leijonmarck et  al. (2013) proposed an environmentally friendly battery cell by adding CNF to a single sheet of paper. Tests proved that the resulting films had acceptable loop performance. Hakkarainen et al. (2016) tested the CNF dressing on burnt skin for wound dressing purposes and determined that

Wood Plastic Composites (WPCs): Applications of Nanomaterials

115

CNF-dressing-covered wound sites heal faster (on average 4 days earlier) than those treated with ordinary lactocapromer dressing. The addition of CNC to the collagen-­ based composite resulted in increased biocompatibility (Li et al. 2014a, b). Another study found that the mechanical properties of CNCs significantly increased when added to poly (D, L-lactic-co-glycolic acid) (PLGA) (Mo et al. 2015). The adhesion properties of CNF have been used for anti-metastatic/anti-cancer (Nurani et  al. 2017). CNF-based hydrogels have been used as carriers for cancer therapy drugs (Bhandari et al. 2017). CNFs have been considered as an environmentally friendly binder in laminate and particulate composite systems (Tajvidi et al. 2016). Herrera et al. (2014) prepared CNC-poly (allylamine hydrochloride) nanocomposite films that can be considered for gas separation and barrier applications. CNF was used to attach the clay to paper surfaces. The CNF-clay layer caused a significant increase in surface smoothness and print density (Hamada and Bousfield 2010). CNFs were used to bond graphite to cellulose nanocomposites. The results showed that the addition of CNF to the paper coating increased the impact resistance (Jabbour et al. 2010). Ghasemi et al. (2017) produced filaments from different CNF suspensions via dry-spun technique and studied the effect of process parameters (different CNF recipes and drying temperatures) on the mechanical properties of the CNF-filaments. Lignin, which is one of the most abundant natural polymers on Earth, has received limited attention despite its remarkable physical and chemical properties and abundance in nature. The heterogeneous molecular structure of lignin material supports the idea of ​​converting lignin material into LNPs. The potential of the LNPs for being utilized in the synthesis of nanostructured materials with enhanced thermal stability, mechanical properties, and barrier performance has been discovered in recent years (Low et al. 2021). The fact that LNPs have high surface-to-volume ratio, improve material properties when added to polymers, have many functional groups, have antioxidant activities, and have properties (e.g., antibacterial properties, protection against ultraviolet radiation, resistance to oxidation, and biocatalytic features) not found in many other natural nanomaterials makes LNPs to attract considerable interest. There are, however, limitations on the development of LNPs and on their use in broader application areas. These limitations are due to the fact that the heterogeneous chemical structure of lignin depends strongly on its extraction method and source. These issues have been addressed in recent studies (Yan et al. 2021; Figueiredo et al. 2018; Zhao et al. 2016). In addition to being applied as precursors for functional materials, the LNPs are now widely used in engineering materials, carbon fibers and composites, antioxidants, thermal/light stabilizers, reinforced materials, and nanomicrocarriers (Rico-García et al. 2020; Liang et al. 2020; Xu et  al. 2021; Salami et  al. 2017; Stojanovska et  al. 2018, 2019; Oveissi et  al. 2018; Amini et al. 2020; Zhang et al. 2020a, b). A list of examples for the application areas of lignin nanomaterials is given in Table 2. Nanohemicellulose materials are known to have superior biocompatibility, bioactivity, and low toxicity. Owing to these features, these lignocellulosic nanomaterials are used in biomedical, food packaging, energy, and environmental applications. In biomedical applications, nanohemicellulose is used in drug delivery, biosensors,

116

M. Zor et al.

Table 2  Application areas of lignin nanomaterials Research area Lignin film based on cellulose fibril

Applied area Reinforcement element

Nanocomposite films of lignin nanoparticles (LNPs), chitosan (CH), and polyvinyl alcohol (PVA)

Antibacterial effect

Nanolignin-based composite

Antibacterial effect

Lignin nanoparticles and poly(methyl methacrylate)(PMMA) nanocomposite

Food packaging films

Lignin/nanocellulose film Reinforcement element

Lignin nanoparticles and polylactidine (PLA) composite film

Reinforcement element

Nanolignin/PLA bionanocomposite

Reinforcement element

Lignin nanoparticles/ PVA nanocomposite films

Food packaging films

Lignin-based sunscreens

Cosmetic

Conclusion Lignin improved the thermal properties and hydrophobicity of the cellulose fibril-based film Showed that dual (PVA/LNP and CH/LNP) and triple (PVA/ CH/LNP) nanocomposite films can significantly inhibit the growth of bacterial plant pathogens The nanolignin-based composite was found to have better bacterial and protective effects on the samples

References Jiang et al. (2019) Yang et al. (2016a, b)

Gîlca et al. (2011), Gîlcă and Popa (2013), Popa et al. (2011) The results showed that the light Yang et al. (2018) transmittance of nanocomposites decreased significantly and the transparency of the layers decreased significantly as the nanolignin content increased Rojo et al. The mechanical properties of (2015) lignocellulose nanofibrils are preserved due to the uniform distribution of lignin Lintinen et al. The results of the tensile tests (2018) confirmed that the composite films have improved mechanical properties due to nanolignin loading Yang et al. When the nanolignin addition (2015a, b) was increased from 1% by weight to 3% by weight, the elongation at break of the melt extruded films increased while the tensile strength and modulus decreased The enhanced thermal stability Tian et al. (2017) of nanocomposite films has been associated with interfacial interaction and compatibility between nanolignin and PVA matrix Compared to commercial Trevisan and sunscreens, creams containing Rezende 10% lignin nanoparticles (2020) exhibited lower light transmission (continued)

Wood Plastic Composites (WPCs): Applications of Nanomaterials

117

Table 2 (continued) Research area Lignin microcapsules

Lignin-based catalyst

Investigation of antioxidant activities between nanolignin and microlignin Hybrid phase change material containing nanolignin

Applied area Conclusion Biocompatibility Proved that lignin microcapsules are noncytotoxic and biocompatible Catalyst The developed catalytic system had high efficiency and recyclability Antioxidant The reducing power of nano effect lignin was found to be higher

References Tortora et al. (2014)

Energy storage

Sipponen et al. (2020)

The material showed higher enthalpy retention values of 99.7% and 98.1% compared with the initial enthalpies for solidification and melting enthalpies after 290 cycles

Pua et al. (2011) Kabir et al. (2019)

and disease therapy. Nanohemicelluloses are produced from microcrystalline cellulose, corn starch, or hemp fiber (Balli et al. 2019). Silica nanoparticles with high hemicellulose content can be synthesized from rice husk and used in various biomedical applications (Athinarayanan et al. 2015). Ma et al. (2018) have reported that quaternized xylan-iron oxide nanoparticles can be used for drug delivery for cancer treatment. Another application area of ​​nanohemicelluloses is environmental cleaning. Membranes and filters can be obtained from hemicellulose-based nanoparticles and nanocomposites. While nanohemicelluloses are used to remove heavy metals from wastewater, nano-biocomposites fibers formed from hemicellulose-­ nano-­iron particles can be used in wastewater treatment in textiles (Irawan et  al. 2017). The strength, abrasion resistance, and favorable barrier properties of nanohemicelluloses allow them to be used as food packaging materials, thereby replacing traditional petroleum-based films (Balli et al. 2019).

4.5 Lignocellulosic Nanomaterials as Reinforcements in Composites Polymer nanocomposites are a class of composite materials composed of a polymer matrix and a reinforcing (filler) nanomaterial that has at least one dimension in the range 1–100  nm (Koo 2006). The green polymer nanocomposites, on the other hand, exhibit unique properties from the combination of both natural fillers and organic polymers. The nano-size effect furnishes nanocomposites with unique properties that cannot be obtained by traditional “macro-” composite materials. Studies with polymer nanocomposites are generally non-synthetic and biodegradable (Gopalan and Dufresne 2003). CNCs were used as fillers for the PVA-CNC

118

M. Zor et al.

nanocomposite matrix. The resulting PVA nanocomposite was water resistant (Fortunati et al. 2013) (Peresin et al. 2014). Dahman and Oktem (2012) reported transparent modified BNC-poly (hydroxyethyl methacrylate) (PHEMA) bionanocomposites. Nanocellulose and boron compounds were used to develop novel hybrid urea formaldehyde polymers and biocomposites (Yildirim and Candan 2021; Yildirim et al. 2021). Another study presents BNC/PVA nanocomposite hydrogels (Yang et al. 2012). Sanna et al. (2013) synthesized a nanocomposite of poly(N-vinyl caprolactam) hydrogels containing CNC. Thanks to its thermoresponsive behavior, the resulting PNVCL-NCC nanocomposite is promising to be used in biomedical applications. Khan et  al. (2013) fabricated CNC-reinforced poly(caprolactone) (PCL) nanocomposite films via compression molding. Compared with the properties of neat PCL films, an addition of 5 wt % NCC resulted in a 62% increase in the strength and an 18% reduction in the CO2 transmission rate. Based on their findings, Khan et al. (2013) suggested that the CNC-PLC nanocomposite films are viable for use in modified atmospheric packaging applications. NCC-­poly(vinylidene fluoride-co-hexafluoropropylene) nanocomposite films have been reported for being used as separators in lithium-ion batteries (Lalia et al. 2012). Candan et al. (2016) developed CNF/nanoclay/pMDI nanocomposites and determined their DMTA characteristics. The production of the polyurethane/CNC nanocomposite was carried out by Rueda et al. (2013). They determined that the nanocomposites are suitable for use in biomedical applications (Rueda et al. 2013). Fahma et al. (2013) synthesized poly(methyl methacrylate) (PMMA)/CNF nanocomposites via immersion precipitation method; the resulting nanocomposites were translucent. Because of its low cost, renewability, and abundance in nature, lignin has been the subject of many research efforts on the green nanocomposites. Saito et al. (2012) used lignin as an additive in polymer matrices. Poly (vinyl alcohol) (PVA) is a nontoxic, water-soluble, polar structure and biodegradable polymer type (Xiong et al. 2018). One study presents the use of modified lignin nanoparticles (LNPs) as reinforcing agents in PVA.  In addition to being transparent, the modified LNP-PVA nanocomposite had superior antioxidant properties. Moreover, its thermal properties were higher compared with the unmodified LNP-reinforced nanocomposite (He et al. 2019b). Lee et al. (2019) synthesized lignin/PVA nanocomposites via electrospinning method. The synthesized composites were found to have UV protective and antimicrobial properties. LNP-PVA nanocomposites for use in UV protection were produced by Ju et al. (2019). The permeability of nanocomposites obtained from LNPs with high surface area was found to be lower (Ju et al. 2019). In another study, LNP-CNC-PVA nanocomposites were introduced (Yang et al. 2016a, b). The compatibility of CNC and LNPs increased transparency and UV resistance in nanocomposites. Xiong et al. (2018) prepared LNP-PVA nanocomposite via solvent. The nanocomposite offered excellent UV absorption properties and exhibited transparency in the visible region. In a similar study, Zhang et al. (2020a, b) synthesized PVA/lignin nanocomposites with excellent UV protection and water vapor barrier properties. In the literature, LNPs have been used as additives in matrix materials such as poly(vinyl alcohol) (PVA), poly (lactic acid) (PLA), rubber, poly (methyl

Wood Plastic Composites (WPCs): Applications of Nanomaterials

119

methacrylate) (PMMA), and polyethylene (PE) to form lignin-based nanocomposites (Wang et al. 2016). Solvent casting and melt extrusion methods were used as two different techniques for the production of PLA-LNP bionanocomposites. Although there was an increase in the mechanical properties of nanocomposites produced by the melt extrusion method, the situation was opposite in nanocomposites produced by solvent casting (Yang et  al. 2015a, b). Jiang et  al. (2020) used nano-sized biochar from waste lignin as a renewable reinforcing filler for styrenebutadiene rubber (SBR). The elongation at the break of the obtained nanocomposite increased 2.4 times, and the tensile strength increased 7.1 times (Jiang et al. 2020). Jiang et  al. (2013) incorporated the lignin nanoparticles into the natural rubber matrix. The effect of lignin nanoparticles was of great importance in improving the mechanical and thermal properties of the nanocomposite. Yang et  al. (2015a, b) fabricated wheat gluten (WG)-LNPl bio-nano-composites using WG and LNPs. LNPs added to WG caused an increase in water sensitivity and UV spectrum absorption. The inclusion of LNPs as additives in the poly(methyl methacrylate) (PMMA) matrix improves thermal stability and provides UV resistance, in addition to showing excellent mechanical properties (Yang et al. 2018). The production of hemicellulose-based nanocomposites and various processing methods are among the current topics of recent times. Various materials such as silver and palladium have been reported in the literature for use in the production of hemicellulose-based nanocomposites (Shah et al. 2015; Du et al. 2019). The xylan-­ silver nanocomposite films were produced by the solution casting method. It has been shown that nanocomposite films can be used in new green food packaging applications thanks to their specially designed multifunctional barrier activity (Haafiz et al. 2019). Bionanocomposite films with mechanical and UV inhibitory properties were produced by using hemicellulose as an additive to nano-sized cellulose fiber films (Yu et al. 2019). In another study, freeze-thaw nanohemicellulose composite films were reported as a result of combinations of CNFs with xylan films (Peng et  al. 2011). Cationic chitosan-nanohemicellulose-based nanocomposites were produced by Chen et al. (2016). The produced hemicellulose-based nanocomposites had excellent thermal properties, low oxygen and water vapor permeability, and superior mechanical strength. It has been reported in a number of studies that the nanocomposites produced with nanohemicellulose nanofibers have superior mechanical properties for food packaging applications (Chen et al. 2016; Peng et al. 2011; Mikkonen and Tenkanen 2012). The addition of nanohemicellulose in modified organic–inorganic nanocomposite films caused an increase in the barrier properties of nanocomposites (Guan et al. 2014a, b). Another study took the proposal of a new hybrid hydrogel. Hemicellulose, polyvinyl alcohol, and nanochitin were used in the study (Guan et al. 2014a, b).

120

M. Zor et al.

5 Conclusion The nanotechnology, which is one of the major technological developments of the twenty-first century, reveals itself in diverse fields of natural sciences and engineering. Nanoscience and nanotechnology offer numerous opportunities to increase the durability of engineered composites. In the development of large-scale structural materials from sustainable wood-based nanomaterials, a number of problems emerge. These problems include the need for improving mechanical properties, minimizing moisture uptake, and obtaining novel features associated with optical, magnetic, and electrical properties. It is possible to address these problems with the aid of nanotechnology. Since wood material (lignocellulosic structure) consists of both organic and biologically degradable components, the threat of depletion of energy resources and the deterioration of the natural cycle have increasingly raised awareness in people and led them to seek for environmentally friendly materials (green materials). With these constructive effects on the environment and human health, nanoscience/nanotechnology applications have been integrated into the composition of a wide variety of commercial products. There is a great demand for non-petroleum, green, and sustainable composite materials. Because of low toxicity, carbon neutral structure, wide range availability, biodegradability, and superior properties, lignocellulosic green nanomaterials have a huge potential to be used in wood plastic composites with enhanced properties.

References Agustin MB, Penttilä PA, Lahtinen M, Mikkonen KS (2019) Rapid and direct preparation of lignin nanoparticles from alkaline pulping liquor by mild ultrasonication. ACS Sustain Chem Eng 7:19925–19934 Al G, Aydemir D, Ayrilmis N, Kaygin B, Gunduz G (2018) The effect of nanoboron nitride on some properties of biopolymer nanocomposites with cellulose nanofibrils and nanoclays. Drvna Industrija 69:43–48 Alqahtani MS, Alqahtani A, Kazi M, Ahmad MZ, Alahmari A, Alsenaidy MA, Syed R (2020) Wound-healing potential of curcumin loaded lignin nanoparticles. J Drug Deliv Sci Technol 60:102020 Altan M, Yildirim H (2010) Mechanical and morphological properties of polypropylene and high-­ density polyethylene matrix composites reinforced with surface modified Nanosized TiO2 particles. World Acad Sci Eng Technol 4:246–251 Amini S, Saudi A, Amirpour N, Jahromi M, Najafabadi SS, Kazemi M, Rafienia M, Salehi H (2020) Application of electrospun polycaprolactone fibers embedding lignin nanoparticle for peripheral nerve regeneration: in vitro and in vivo study. Int J Biol Macromol 159:154–173 Antov P, Jivkov V, Savov V, Simeonova R, Yavorov N (2020) Structural application of eco-­ friendly composites from recycled wood fibres bonded with magnesium lignosulfonate. Appl Sci 10:7526 Antov P, Savov V, Krišt’ák L, Réh R, Mantanis GI (2021a) Eco-friendly, high-density fiberboards bonded with urea-formaldehyde and ammonium lignosulfonate. Polymers 13:220 Antov P, Savov V, Trichkov N, Krišťák Ľ, Réh R, Papadopoulos AN, Taghiyari HR, Pizzi A, Kunecová D, Pachikova M (2021b) Properties of high-density fiberboard bonded with

Wood Plastic Composites (WPCs): Applications of Nanomaterials

121

urea–formaldehyde resin and ammonium lignosulfonate as a bio-based additive. Polymers 13(16):2775 Anwar Z, Gulfraz M, Irshad M (2014) Agro-industrial lignocellulosic biomass a key to unlock the future bio-energy: a brief review. J Radiat Res Appl Sci 7:163–173 Ashori A (2013) Effects of nanoparticles on the mechanical properties of rice straw/polypropylene composites. J Compos Mater 47:149–154 Aslan M (2008) Odun plastik kompozitlerinde geri dönüşüm ve atık malzeme kullanımı.VI. Ulusal orman fakülteleri öğrencileri kongresi. 63–67 Athinarayanan J, Periasamy VS, Alhazmi M, Alatiah KA, Alshatwi AA (2015) Synthesis of biogenic silica nanoparticles from rice husks for biomedical applications. Ceram Int 41(1):275–281 Aulin C, Ström G (2013) Multilayered alkyd resin/nanocellulose coatings for use in renewable packaging solutions with a high level of moisture resistance. Ind Eng Chem Res 52:2582–2589 Aydemir D, Kiziltas A, Gardner DJ, Han Y, Gunduz G (2014a) Morphological characterization of foamed natural filler-reinforced styrene-maleic anhydride (SMA) composites. J Porous Mater 21:1059–1067 Aydemir D, Kiziltas A, Gardner DJ, Han Y, Gunduz G (2014b) Influence of micro- and nanonatural fillers on mechanical and physical properties of foamed SMA composites. Polym-Plast Technol Eng 53:1825–1831 Aydemir D, Kiziltas A, Kiziltas EE, Gardner DJ, Gunduz G (2015) Heat-treated wood–nylon 6 composites. Compos Part B Eng 68:414–423 Aydemir D, Kiziltas A, Gardner DJ, Han Y, Gunduz G (2015a) Thermal analysis of micro- and nano lignocellulosic reinforced styrene maleic anhydride composite foams. Int J Polym Anal Charact 20:231–239 Aydemir D, Kiziltas A, Gunduz G, Han Y, Gardner DJ (2015b) Natural fillers-filled styrene maleic anhydride copolymer composites. Wood Res 60:167–174 Ballesteros LF, Michelin M, Vicente AA, Teixeira JA, Cerqueira MÂ (2018) Use of lignocellulosic materials in bio-based packaging. In: Lignocellulosic materials and their use in bio-based packaging. Springer, Cham, pp 65–85 Balli B, Calimli MH, Kuyuldar E, Sen F (2019) Synthesis, characterization, and applications of hemicellulose based eco-friendly polymer composites. In: Inamuddin, Thomas S, Kumar Mishra R, Asiri A (eds) Sustainable polymer composites and nanocomposites. Springer, Cham Bari E, Taghiyari HR, Schmidt O, Ghorbani A, Aghababaei H (2015) Effects of nano-clay on biological resistance of woodplastic composite against five wood-deteriorating fungi. Maderas Cienc Tecnol 17(1):205–212 Basu A, Lindh J, Ålander E, Strømme M, Ferraz N (2017) On the use of ion-crosslinked nanocellulose hydrogels for wound healing solutions: physicochemical properties and application-­ oriented biocompatibility studies. Carbohydr Polym 174:299–308 Bayer IS, Guzman-Puyol S, Heredia-Guerrero JA, Ceseracciu L, Pignatelli F, Ruffilli R, Cingolani R, Athanassiou A (2014) Direct transformation of edible vegetable waste into bioplastics. Macromolecules 47:5135–5143 Beisl S, Adamcyk J, Friedl A (2020) Direct precipitation of lignin nanoparticles from wheat straw organosolv liquors using a static mixer. Molecules 25:1388 Berglund L (2005) Cellulose-based nanocomposites. In: Natural fibers, biopolymers and biocomposites. CRC Press, pp 835–858 Bertolo MRV, Brenelli de Paiva LB, Nascimento VM, Gandin CA, Neto MO, Driemeier CE, Rabelo SC (2019) Lignins from sugarcane bagasse: renewable source of nanoparticles as Pickering emulsions stabilizers for bioactive compounds encapsulation. Ind Crop Prod 140:111591 Bhandari J, Mishra H, Mishra PK, Wimmer R, Ahmad ZJ, Talegaonkar S (2017) Cellulose nanofiber aerogel as a promising biomaterial for customized oral drug delivery. Int J Nanomedicine 12:2021–2031 Bledzki AK, Sperber VE, Faruk O (2002) Natural and wood fibre reinforcement in polymers. Rapra Review Reports, vol. 13, No. 8, Report 152

122

M. Zor et al.

Brown BJ, Hanson ME, Liverman DM, Merideth RW (1987) Global sustainability: toward definition, environmental management, vol 11. Springer, New York, pp 713–719 Brownell B (2021) Control or affect? The paradox of 3D-printed wood. Technol Arch Des 5(1):112–115 Cai X, Riedl B, Wan H, Zhang SY (2010) Montmorillonite nanoparticle distribution and morphology in melamine-urea-formaldehyde resin-impregnated wood nanocomposites. Wood Fiber Sci 42:285–291 Calvino C, Macke N, Kato R, Rowan SJ (2020) Development, processing and applications of bio-­ sourced cellulose nanocrystal composites. Prog Polym Sci 103:101221 Calvo-Flores FG, Dobado JA (2010) Lignin as renewable raw material. ChemSusChem 3:1227–1235 Candan Z (2012) Nanoparticles use in manufacture of wood-based sandwich panels and laminate flooring and its effects on technological properties. Ph.D.  Dissertation, Istanbul University, Istanbul Candan Z, Akbulut T (2013) Developing environmentally friendly wood composite panels by nanotechnology. Bioresources 8:3590–3598 Candan Z, Akbulut T (2014) Nano-engineered plywood panels: performance properties. Compos Part B 64:155–161 Candan Z, Akbulut T (2015) Physical and mechanical properties of nanoreinforced particleboard composites. Maderas Cienc Tecnol 17(2):319–334 Candan Z, Gardner DJ, Shaler SM (2016) Dynamic mechanical thermal analysis (DMTA) of cellulose nanofibril/nanoclay/pMDI nanocomposites. Compos Part B 90:126–132 Candan Z, Tozluoglu A, Gonultas O, Yildirim M, Fidan H, Alma MH, Salan T (2022) Nanocellulose: sustainable biomaterial for developing novel adhesives and composites. In: Industrial applications of nanocellulose and its nanocomposites. Elsevier, United Kingdom, pp 49–137 Carmichael E, Ghassemieh E, Lyons G (2020) Biorefining of lignocellulosic feedstock and waste materials using ionic liquid. Mater Sci Eng B 262:114741 Carpenter AW, de Lannoy CF, Wiesner MR (2015) Cellulose nanomaterials in water treatment technologies. Environ Sci Technol 49(9):5277–5287 Carvalheiro F, Duarte LC, Girio FM (2008) Hemicellulose biorefineries: a review on biomass pretreatments. J Sci Ind Res 67:849–864 Chaochanchaikul K, Sombatsompop N (2011) Stabilizations of molecular structures and mechanical properties of PVC and wood/PVC composites by Tinuvin and TiO2 stabilizers. Polym Eng Sci 7:1354–1365 Chaochanchaikul K, Rosarpitak V, Sombatsompop N (2011) Structural and thermal stabilizations of PVC and wood/PVC composites by metal stearates and organotin. Bioresources 6(3):3115–3131 Chauhan PK (2020) Lignin nanoparticles: eco-friendly and versatile tool for new era. Bioresour Technol Rep 9:100374 Chen L (2009) Extrudable relamine resin for wood plastic composite, Master of Science Civil Engineering. Washington State Unıversity/ Department of Civil and Environmental Engineering, 8–9 Chen GG, Qi XM, Guan Y, Peng F, Yao CL, Sun RC (2016) High strength hemicellulose-based nanocomposite film for food packaging applications. ACS Sustain Chem Eng 4(4):1985–1993 Chen L, Shi Y, Gao B, Zhao Y, Jiang Y, Zha Z, Xue W, Gong L (2020) Lignin nanoparticles: green synthesis in a γ-valerolactone/water binary solvent and application to enhance antimicrobial activity of essential oils. ACS Sustain Chem Eng 8:714–722 Clemons CM, Caulfi DF (2005) Natural fibers. Functional fillers for plastics. Wiley-VCH, Weinheim, pp 195–220 Cornwall W (2016) Tall Timber. Science 353:1354–1356 Crowther TW, Glick HB, Covey KR, Bettigole C, Maynard D, Thomas SM et al (2015) Mapping tree density at a global scale. Nature 525:201–205

Wood Plastic Composites (WPCs): Applications of Nanomaterials

123

Dahman Y, Oktem AT (2012) Optically transparent nanocomposites reinforced with modified biocellulose nanofibers. J Appl Polym Sci 126(S1):E188–E196 Dai L, Liu R, Hu LQ, Zou ZF, Si CL (2017) Lignin nanoparticle as a novel green carrier for the efficient delivery of resveratrol. ACS Sustain Chem Eng 5:8241–8249 Daus S, Heinze T (2010) Xylan-based nanoparticles: prodrugs for ibuprofen release. Macromol Biosci 10(2):211–220 De Windt TS, Hendriks JAA, Zhao X, Vonk LA, Creemers LB, Dhert WJA, Randolph MA, Saris DBF (2014) Concise review: Unraveling stem cell cocultures in regenerative medicine: which cell interactions steer cartilage regeneration and how? Stem Cells Transl Med 3:723–733 Deka BK, Maji TK (2012) Effect of SiO2 and nano clay on the properties of wood polymer nanocomposite. Polym Bull 10:60–75 Deka BK, Mandal M, Maji TK (2012) Effect of nanoparticles on flammability, UV resistance, biodegradability, and chemical resistance of wood polymer nanocomposite. Ind Eng Chem Res 51:11881–11891 DePolo JL, Baird DG (2009) Particulate reinforced PC/PBT composites. II.  Effect of nano-­ clay particles on dimensional stability and structure-property relationships. Polym Compos 30:200–213 Devi RR, Maji TK (2007) Effect of glycidyl methacrylate on the physical properties of wood− polymer composites. Polym Compos 28:1 Devi RR, Maji TK (2012) Effect of nano-ZnO on thermal, mechanical, UV stability, and other physical properties of wood polymer composites. Ind Eng Chem Res 51:10 Doh H, Lee MH, Whiteside WS (2020) Physicochemical characteristics of cellulose nanocrystals isolated from seaweed biomass. Food Hydrocoll 102:105542 Domingues RM, Gomes ME, Reis RL (2014) The potential of cellulose nanocrystals in tissue engineering strategies. Biomacromolecules 15(7):2327–2346 Drobny JG (2014) Additives. Handbook of thermoplastic elastomers. Elsevier. 2014:17–32. Du F, Zhang L, Ma J, Peng X (2019) Hemicelluloses supported palladium/xylan nanocomposites containing N and O ligands: highly-performance heterogeneous catalysts for Suzuki reaction. Carbohydr Polym 217:224–231 El-Haggar SM, Kamel MA (2011) Wood plastic composites. Adv Compos 13:325–343 El-Samahy MA, Mohamed SA, Rehim MHA, Mohram ME (2017) Synthesis of hybrid paper sheets with enhanced air barrier and antimicrobial properties for food packaging. Carbohydr Polym 168:212–219 Fahma F, Hori N, Iwata T, Takemura A (2013) The morphology and properties of poly (methyl methacrylate)-cellulose nanocomposites prepared by immersion precipitation method. J Appl Polym Sci 128(3):1563–1568 Figueiredo P, Lintinen K, Hirvonen JT, Kostiainen MA, Santos HA (2018) Properties and chemical modifications of lignin: towards lignin-based nanomaterials for biochemical applications. Prog Mater Sci 93:233–269 Fornué E, Graham Allan G, Héctor J, González G, Saucedo J (2011) Fundamental aspects of adhesion between cellulosic surfaces in contact—a review. O Pap 72:85–90 Foroughi F, Rezvani Ghomi E, Morshedi Dehaghi F, Borayek R, Ramakrishna S (2021) A review on the life cycle assessment of cellulose: from properties to the potential of making it a low carbon material. Mater Basel 14:714 Fortunati E, Puglia D, Monti M, Santulli C, Maniruzzaman M, Kenny JM (2013) Cellulose nanocrystals extracted from okra fibers in PVA nanocomposites. J Appl Polym Sci 128(5):3220–3230 Frangville C, Rutkevicius M, Richter AP, Velev OD, Stoyanov SD, Paunov VN (2012) Fabrication of environmentally biodegradable lignin nanoparticles. Chemphyschem 13:4235–4243 Fu GQ, Su LY, Yue PP, Huang YH, Bian J, Li MF, Peng F, Sun RC (2019) Syntheses of xylan stearate nanoparticles with loading function from by-products of viscose fiber mills. Cellulose 26:7195–7206

124

M. Zor et al.

Gao A, Chen H, Tang J, Xie K, Hou A (2020) Efficient extraction of cellulose nanocrystals from waste Calotropis gigantea fiber by SO42-/TiO2 nano-solid superacid catalyst combined with ball milling exfoliation. Ind Crop Prod 152:112524 Gardner DJ, Han Y, Wang L (2015a) Forestry report wood–plastic composite. Technology 1:139–150 Gardner DJ, Han Y, Wang L (2015b) Wood–plastic composite technology. Curr For Rep 1:139–150 Ghalehno MD, Kord B, Sheshkal BN (2020) Mechanical and physical properties of wood/polyethylene composite reinforced with TiO2 nanoparticles. Cerne 26:474–481 Ghasemi S, Tajvidi M, Bousfield D, Gardner D, Gramlich W (2017) Dry-spun neat cellulose nanofibril filaments: influence of drying temperature and nanofibril structure on filament properties. Polymers 9:392 Ghofrani-Isfahani P, Baniamerian H, Tsapekos P, Alvarado-Morales M, Kasama T, Shahrokhi M et al (2020) Effect of metal oxide based TiO2 nanoparticles on anaerobic digestion process of lignocellulosic substrate. Energy 191:116580 Gîlcă IA, Popa VI (2013) Study on biocidal properties of some nanoparticles based on epoxy lignin. Cellul Chem Technol 47:239–245 Gîlca IA, Capraru AM, Grama S, Popa VI (2011) Agents for wood bioprotection based on natural aromatic compounds and their complexes with copper and zinc. Cellul Chem Technol 45:227 Gopakumar DA, Pai AR, Pottathara YB, Pasquini D, Carlos de Morais L, Luke M, Kalarikkal N, Grohens Y, Thomas S (2018) Cellulose nanofiber-based polyaniline flexible papers as sustainable microwave absorbers in the X-band. ACS Appl Mater Interfaces 10:20032–20043 Gopalan NK, Dufresne A (2003) Crab shell chitin whisker reinforced natural rubber nanocomposites. 1. Processing and swelling behavior. Biomacromolecules 4:657–665 Guan Y, Zhang B, Bian J, Peng F, Sun RC (2014a) Nanoreinforced hemicellulose-based hydrogels prepared by freeze–thaw treatment. Cellulose 21(3):1709–1721 Guan Y, Zhang B, Tan X, Qi XM, Bian J, Peng F, Sun RC (2014b) Organic–inorganic composite films based on modified hemicelluloses with clay nanoplatelets. ACS Sustain Chem Eng 2(7):1811–1818 Guo J, Cao R, Huang K, Xu Y (2020) Comparison of selective acidolysis of xylan and enzymatic hydrolysability of cellulose in various lignocellulosic materials by a novel xylonic acid catalysis method. Bioresour Technol 304:122943 Guz IA (2012) Continuum solid mechanics at nano-scale: how small can it go? J Nanomater Mol Nanotechnol 1:1 Haafiz KM, Taiwo OF, Razak N, Rokiah H, Hazwan HM, Rawi NFM, Khalil HA (2019) Development of green MMT-modified hemicelluloses based nanocomposite film with enhanced functional and barrier properties. Bioresources 14(4):8029–8047 Habibi Y, Lucia LA (2012) Polysaccharide building blocks: a sustainable approach to the development of renewable biomaterials. Wiley, Hoboken Habibi Y, Lucia LA, Rojas OJ (2010) Cellulose nanocrystals: chemistry, self-assembly, and applications. Chem Rev 110:3479–3500 Haghighi Poshtiri A, Taghiyari HR, Karimi AN (2013) The optimum level of nano-wollastonite consumption as a fire-retardant in poplar wood (Populus nigra). Int J Nano Dimens 4:141–151 Hakkarainen T, Koivuniemi R, Kosonen M, Escobedo-Lucea C, Sanz-Garcia A, Vuola J, Valtonen J, Tammela P, Mäkitie A, Luukko K et al (2016) Nanofibrillar cellulose wound dressing in skin graft donor site treatment. J Control Release 244:292–301 Hamada H, Bousfield D (2010) Nanofibrillated cellulose as a coating agent to improve print quality of synthetic fiber sheets. TAPPI J 9:25–29 Hänninen A, Sarlin E, Lyyra I, Salpavaara T, Kellomäki M, Tuukkanen S (2018) Nanocellulose and chitosan based films as low cost, green piezoelectric materials. Carbohydr Polym 202:418–424 Hassanin AH, Hamouda T, Candan Z, Kilic A, Akbulut T (2016) Developing high-performance hybrid green composites. Compos Part B 92:384–394 Hayle ST, Gonfa GG (2014) Synthesis, and characterization of titanium oxide nanomaterials using sol-gel method. Am J Nanosci Nanotechnol 2:1–7

Wood Plastic Composites (WPCs): Applications of Nanomaterials

125

He X, Deng H, Hwang H (2019a) The current application of nanotechnology in food and agriculture. J Food Drug Anal 27:1–21 He X, Luzi F, Hao X, Yang W, Torre L, Xiao Z et al (2019b) Thermal, antioxidant and swelling behaviour of transparent polyvinyl (alcohol) films in presence of hydrophobic citric acidmodified lignin nanoparticles. Int J Biol Macromol 127:665–676 Herrera MA, Mathew AP, Oksman K (2014) Gas permeability and selectivity of cellulose nanocrystals films (layers) deposited by spin coating. Carbohydr Polym 112:494–501 Hoeng F, Denneulin A, Bras J (2016) Use of nanocellulose in printed electronics: a review. Nanoscale 8:13131–13154 Hussin MH, Trache D, Chuin CTH, Fazita MN, Haafiz MM, Hossain MS (2019) Extraction of cellulose nanofibers and their eco-friendly polymer composites. In: Sustainable polymer composites and nanocomposites. Springer, Cham, pp 653–691 Iqbal HMN, Ahmed I, Zia MA, Irfan M (2011) Purification and characterization of the kinetic parameters of cellulase produced from wheat straw by Trichoderma viride under SSF and its detergent compatibility. Adv Biosci Biotechnol 2:149–156 Iqbal HMN, Kyazze G, Keshavarz T (2013) Advances in the valorization of lignocellulosic materials by biotechnology: an overview. Bioresources 8:3157–3176 Irawan C, Nata IF, Putra MD, Elma M, Hanisa KF (2017) Biocomposite materials of eleocharis dulcis fibers with iron (III) nanoparticles and its potential for Sasirangan textile wastewater treatment. Int J Adv Sci Eng Inf Technol 7(4):1234–1240 Ismaeilimoghadam S, Shamsian M, Bayat Kashkoli A, Kord B (2015) Evaluation of effect of nano SiO2 on the physical, mechanical and morphological properties of hybrid nanocomposite from polypropylene-wood flour. Iran J Wood Pap Sci Res (Persian) 30:266–277 Ismaeilimoghadam S, Masoudifar M, Nosrati B, Shamsian M (2016) Effects of inorganic nanoparticles on mechanical and morphological properties of wood flour-polypropylene nanocomposites. Drewno 59:127–137 Jabbour L, Gerbaldi C, Chaussy D, Zeno E, Bodoardo S, Beneventi D (2010) Microfibrillated cellulose–graphite nanocomposites for highly flexible paper-like Li-ion battery electrodes. J Mater Chem 20:7344 Jabbour L, Destro M, Chaussy D, Gerbaldi C, Penazzi N, Bodoardo S, Beneventi D (2013) Flexible cellulose/LiFePO4 paper-cathodes: toward eco-friendly all-paper Li-ion batteries. Cellulose 20:571–582 Jeong SS, Böckenfeld N, Balducci A, Winter M, Passerini S (2012) Natural cellulose as binder for lithium battery electrodes. J Power Sources 199:331–335 Jiang C, He H, Jiang H, Ma L, Jia DM (2013) Nano-lignin filled natural rubber composites: preparation and characterization. Express Polym Lett 7(5) Jiang Y, Liu X, Yang Q, Song X, Qin C, Wang S, Li K (2019) Effects of residual lignin on composition, structure and properties of mechanically defibrillated cellulose fibrils and films. Cellulose 26:1577–1593 Jiang C, Bo J, Xiao X, Zhang S, Wang Z, Yan G et al (2020) Converting waste lignin into nanobiochar as a renewable substitute of carbon black for reinforcing styrene-butadiene rubber. Waste Manag 102:732–742 Ju T, Zhang Z, Li Y, Miao X, Ji J (2019) Continuous production of lignin nanoparticles using a microchannel reactor and its application in UV-shielding films. RSC Adv 9:24915–24921 Kabir AS, Yuan ZS, Kuboki T, Xu CC (2019) Development of lignin-based antioxidants for polymers. In: Production of materials from sustainable biomass resources. Springer, Singapore, pp 39–59 Kai D, Tan MJ, Chee PL, Chu YK, Yap YL, Loh XJ (2016) Towards lignin-based functional materials in a sustainable world. Green Chem 18:1175–1200 Karakuş K (2008) Üniversitemizdeki Polietilen ve Polipropilen atıkların Polimer Kompozit Üretiminde Değerlendirilmesi. Yüksek Lisans Tezi. Kahramanmaraş Sütçü İmam Üniversitesi Fen Bilimleri Enstitütüsü. Kahramanmaraş

126

M. Zor et al.

Karakuş K, Aydemir D, Öztel A, Gunduz G, Mengeloglu F (2017) Nanoboron nitride-filled heat-­ treated wood polymer nanocomposites: comparison of different multicriteria decision-making models to predict optimum properties of the nanocomposites. J Compos Mater 51:4205–4218 Kargarzadeh H, Mariano M, Gopakumar D, Ahmad I, Thomas S, Dufresne A, Huang J, Lin N (2018) Advances in cellulose nanomaterials. Cellulose 25:2151–2189 Kaymakci A (2020) Effect of sepiolite clay nanofibers on physical, mechanical, and thermal properties of wood-plastic nanocomposites. J Thermoplast Compos Mater 0892705720939171 Kaymakcı A, Ayrılmış N (2014) Waste chestnut shell as a source of reinforcing fillers for polypropylene composites. J Thermoplast Compos Mater 27:1054–1064 Khalil HPSA, Davoudpour Y, Islam MN, Mustapha A, Sudesh K, Dungani R, Jawaid M (2014) Production and modification of nanofibrillated cellulose using various mechanical processes: a review. Carbohydr Polym 99:649–665 Khan RA, Beck S, Dussault D, Salmieri S, Bouchard J, Lacroix M (2013) Mechanical and barrier properties of nanocrystalline cellulose reinforced poly (caprolactone) composites: effect of gamma radiation. J Appl Polym Sci 129(5):3038–3046 Kim J, Cai Z, Chen Y (2010) Biocompatible bacterial cellulose composites for biomedical application. J Nanotechnol Eng Med 1:011006 Kim S, Fernandes MM, Matama T, Loureiro A, Gomes AC, Cavaco-Paulo A (2013) Chitosan–lignosulfonates sono-chemically prepared nanoparticles: characterisation and potential applications. Colloids Surf B Biointerfaces 103:1–8 Kim JH, Lee D, Lee YH, Chen W, Lee SY (2019) Nanocellulose for energy storage systems: beyond the limits of synthetic materials. Adv Mater 31:1804826 Klemm D, Fink HP et al (2005) Cellulose: fascinating biopolymer and sustainable raw material. Angew Chem Int Ed 44:3358–3393 Klemm D, Kramer F, Moritz S, Lindström T, Ankerfors M, Gray D, Dorris A (2011) Nanocelluloses: a new family of nature-based materials. Angew Chem Int Ed 50:5438–5466 Kojima Y, Ishino A, Kobori H, Suzuki S, Ito H, Makise R, Higuchi I, Okamoto M (2015) Reinforcement of wood flour board containing ligno-cellulose nanofiber made from recycled wood. J Wood Sci 61:492–499 Koo JH (2006) Polymer nanocomposites: processing, characterization, and applications. McGraw-Hill Kord B, Taghizadeh Haratbar D (2016) Influence of fiber surface treatment on the physical and mechanical properties of wood flour-reinforced polypropylene bionanocomposites. J Thermoplast Compos Mater 29:979–992 Kumar S, Negi YS (2012) Corn cob xylan-based nanoparticles: Ester prodrug of 5-aminosalicylic acid for possible targeted delivery of drug. J Pharm Sci Res 4:1995–2003 Kumar P, Barrett DM, Delwiche MJ, Stroeve P (2009) Methods for pretreatment of lignocellulosic biomass for efficient hydrolysis and biofuel production. Ind Eng Chem Res 48:3713–3729 Kumar SU, Gopinath P, Negi YS (2017) Synthesis and bio-evaluation of xylan-5-fluorouracil-1-acetic acid conjugates as prodrugs for colon cancer treatment. Carbohydr Polym 157:1442–1450 Kumar SU, Kumar V, Priyadarshi R, Gopinath P, Negi YS (2018) pH-responsive prodrug nanoparticles based on xylan-curcumin conjugate for the efficient delivery of curcumin in cancer therapy. Carbohydr Polym 188:252–259 Kumar V, Kumar B, Deeba F, Bano S, Kulshreshtha A, Gopinath P, Negi YS (2019) Lipophilic 5-fluorouracil prodrug encapsulated xylan-stearic acid conjugates nanoparticles for colon cancer therapy. Int J Biol Macromol 128:204–213 Lalia BS, Samad YA, Hashaikeh R (2012) Nanocrystalline-cellulose-reinforced poly (vinylidenefluoride-­co-hexafluoropropylene) nanocomposite films as a separator for lithium ion batteries. J Appl Polym Sci 126(S1):E442–E448 Lavoine N, Desloges I, Dufresne A, Bras J (2012) Microfibrillated cellulose—its barrier properties and applications in cellulosic materials: a review. Carbohydr Polym 90:735–764

Wood Plastic Composites (WPCs): Applications of Nanomaterials

127

Lee BR, Oh ES (2013) Effect of molecular weight and degree of substitution of a sodium-­ carboxymethyl cellulose binder on Li4Ti5O12 anodic performance. J Phys Chem C 117:4404–4409 Lee E, Song Y, Lee S (2019) Crosslinking of lignin/poly (vinyl alcohol) nanocomposite fiber webs and their antimicrobial and ultraviolet-protective properties. Text Res J 89:3–12 Leijonmarck S, Cornell A, Lindbergh G, Wågberg L (2013) Single-paper flexible Li-ion battery cells through a paper-making process based on nano-fibrillated cellulose. J Mater Chem A 1:4671–4677 Li D (2012) Nanostructuring materials towards conventionally unachievable combination of desired properties. J Nanomater Mol Nanotechnol 1:1 Li F, Ren S, Zhang W, Xu Z, Xie G, Chen Y, Peng L (2013a) Arabinose substitution degree in xylan positively affects lignocellulose enzymatic digestibility after various NaOH/H2SO4 pretreatments in Miscanthus. Bioresour Technol 130:629–637 Li Q, McGinnis S, Sydnor C, Wong A, Renneckar S (2013b) Nanocellulose life cycle assessment. ACS Sustain Chem Eng 1:919–928 Li J, Li D, Song Z, Shang S, Guo Y (2014a) Preparation and properties of wood plastic composite reinforced by ultralong cellulose nanofibers. Polym Compos 37:1206–1215 Li W, Guo R, Lan Y, Zhang Y, Xue W, Zhang Y (2014b) Preparation and properties of cellulose nanocrystals reinforced collagen composite films. J Biomed Mater Res A 102:1131–1139 Liang R, Zhao J, Li B, Cai P, Loh XJ, Xu C, Chen P, Kai D, Zheng L (2020) Implantable and degradable antioxidant poly (ε-caprolactone)-lignin nanofiber membrane for effective osteoarthritis treatment. Biomaterials 230:119601 Lievonen M, Valle-Delgado JJ, Mattinen ML, Hult EL, Lintinen K, Kostiainen MA, Paananen A, Szilvay GR, Osterberg M (2016) A simple process for lignin nanoparticle preparation. Green Chem 18:1416 Lin X, Zhao J, Wu M, Kuga Sh HY (2016) Green synthesis of gold, platinum and palladium nanoparticles by lignin and hemicellulose. J Microbiol Biotechnol 5(4):14–18 Lintinen K, Xiao Y, Ashok RB, Leskinen T, Sakarinen E, Sipponen M, Muhammad F, Oinas P, Österberg M, Kostiainen M (2018) Closed cycle production of concentrated and dry redispersible colloidal lignin particles with a three solvent polarity exchange method. Green Chem 20:843–850 Liu W, Du H, Zhang M, Liu K, Liu H, Xie H et al (2020) Bacterial cellulosebased composite scaffolds for biomedical applications: a review. ACS Sustain Chem Eng 8:7536–7562 Liu K, Du H, Zheng T, Liu H, Zhang M, Zhang R, Li H, Xie H, Zhang X, Ma M, Si C (2021) Recent advances in cellulose and its derivatives for oilfield applications. Carbohydr Polym 259:117740 Low LE, Teh KC, Siva SP, Chew IML, Mwangi WW, Chew CL, Goh B-H, Chan ES, Tey BT (2021) Lignin nanoparticles: the next green nanoreinforcer with wide opportunity. Environ Nanotechnol Monit Manag 15:100398 Ma J, Li D, Zhong L, Du F, Tan J, Yang J, Peng X (2018) Synthesis and characterization of biofunctional quaternized xylan-Fe2O3 core/shell nanocomposites and modification with polylysine and folic acid. Carbohydr Polym 199:382–389 Maeda H, Nakajima M, Hagiwara T, Sawaguchi T, Yano S (2006) Bacterial cellulose/silica hybrid fabricated by mimicking biocomposites. J Mater Sci 41:5646–5656 Malherbe S, Cloete TE (2002) Lignocellulose biodegradation: fundamentals and applications. Rev Environ Sci Biotechnol 1:105–114 Markstedt K, Mantas A, Tournier I, Martínez Ávila H, Hagg D, Gatenholm P (2015) 3D bioprinting human chondrocytes with nanocellulose–alginate bioink for cartilage tissue engineering applications. Biomacromolecules 16(5):1489–1496 Marutzky R (2004) Fifth global wood and natural fiber composites symposium, 27–28 April, Kassel Mengeloğlu F, Çavuş V (2021) Long term natural weathering of PP based WPCs: the effect of TiO2 on selected color, physical, mechanical, morphological and chemical properties. In:

128

M. Zor et al.

Mavinkere Rangappa S, Parameswaranpillai J, Kumar MH, Siengchin S (eds) Wood polymer composites, Composites science and technology. Springer, Singapore Mengeloglu F, Karakus K (2008) Polymer-composites from recyled high density polyethylene and waste lignocellulosic materials. Fresenius Environ Bull 17-211-217 Mertaniemi H, Escobedo-Lucea C, Sanz-Garcia A, Gandía C, Mäkitie A, Partanen J, Ikkala O, Yliperttula M (2016) Human stem cell decorated nanocellulose threads for biomedical applications. Biomaterials 82:208–220 Merzoug A, Bouhamida B, Sereir Z, Bezazi A, Kilic A, Candan Z (2020) Quasi-static and dynamic mechanical thermal performance of date palm/glass fiber hybrid composites. J Ind 51 (5_suppl):7599S–621S Metreveli G, Wågberg L, Emmoth E, Belák S, Strømme M, Mihranyan AA (2014) A size-­exclusion nanocellulose filter paper for virus removal. Adv Healthc Mater 3:1546–1550 Miao C, Hamad WY (2019) Critical insights into the reinforcement potential of cellulose nanocrystals in polymer nanocomposites. Curr Opin Solid State Mater Sci 23:100761 Mikkonen KS, Tenkanen M (2012) Sustainable food-packaging materials based on future biorefinery products: Xylans and mannans. Trends Food Sci Technol 28(2):90–102 Millon LE, Guhados G, Wan W (2008) Anisotropic polyvinyl alcohol—bacterial cellulose nanocomposite for biomedical applications. J Biomed Mater Res B Appl Biomater 86:444–452 Missoum K, Martoïa F, Belgacem MN, Bras J (2013) Effect of chemically modified nanofibrillated cellulose addition on the properties of fiber-based materials. Ind Crop Prod 48:98–105 Mo Y, Guo R, Liu J, Lan Y, Zhang Y, Xue W, Zhang Y (2015) Preparation and properties of PLGA nanofiber membranes reinforced with cellulose nanocrystals. Colloids Surf B Biointerfaces 132:177–184 Mohanty AK, Misra M, Drzal LT (2002) Sustainable bio-composites from renewable resources: opportunities and challenges in the green materials world. J Polym Environ 10:19–26 Mokhena T, John M (2020) Cellulose nanomaterials: new generation materials for solving global issues. Cellulose 27:1149–1194 Mondal S (2018) Review on nanocellulose polymer nanocomposites. Polym-Plast Technol Eng 57:1377–1391 Montanari C, Olsén P, Berglund LA (2021) Sustainable wood nanotechnologies for wood composites processed by InSitu polymerization. Front Chem 9:682883 Moohan J, Stewart SA, Espinosa E, Rosal A, Rodríguez A, Larrañeta E et  al (2020) Cellulose nanofibers and other biopolymers for biomedical applications. Rev Appl Sci 10:65 Moon RJ, Martini A, Nairn J, Simonsen J, Youngblood J (2011) Cellulose nanomaterials review: structure, properties and nanocomposites. Chem Soc Rev 40:3941–3994 Morrell JJ, Silva Guzman A (2006) Laboratory methods for assessing the resistance of wood plastic composites to fungal attack; IRG/WP/06-20340. Stockholm, International Research Group on Wood Protection Ndiaye D, Verney V, Askanian H, Commereuc S, Tidjani A (2013) Morphology, thermal behavior and dynamic rheological properties of wood polypropylene composites. Mater Sci Appl 4:730–738 Nikmatin S, Syafiuddin A, Hong Kueh AB, Maddu A (2017) Physical, thermal, and mechanical properties of polypropylene composites filled with rattan nanoparticles. J Appl Res Technol 15:386–395 Nurani M, Akbari V, Taheri A (2017) Preparation and characterization of metformin surface modified cellulose nanofiber gel and evaluation of its anti-metastatic potentials. Carbohydr Polym 165:322–333 Olad A, Doustdar F, Gharekhani H (2020) Fabrication and characterization of a starch-based superabsorbent hydrogel composite reinforced with cellulose nanocrystals from potato peel waste. Colloids Surf Physicochem Eng Asp 601:124962 Oun AA, Shankar S, Rhim JW (2020) Multifunctional nanocellulose/metal and metal oxide nanoparticle hybrid nanomaterials. Crit Rev Food Sci Nutr 60(3):435–460

Wood Plastic Composites (WPCs): Applications of Nanomaterials

129

Oveissi F, Naficy S, Le TYL, Fletcher DF, Dehghani F (2018) Tough and processable hydrogels based on lignin and hydrophilic polyurethane. ACS Appl Bio Mater 1(6):2073–2081 Özmen N, Çetin NS, Narlıoğlu N, Çavuş V, Altuntaş E (2014) Utilisation of MDF waste for wood plastic composites production. SDÜ Fac For J 15:65–71 Park NM, Choi S, Oh JE, Hwang DY (2019) Facile extraction of cellulose nanocrystals. Carbohydr Polym 223:115114 Peng BL, Dhar N, Liu HL, Tam KC (2011) Chemistry and applications of nanocrystalline cellulose and its derivatives: a nanotechnology perspective. Can J Chem Eng 89(5):1191–1206 Pennells J, Godwin ID, Amiralian N, Martin DJ (2020) Trends in the production of cellulose nanofibers from non-wood sources. Cellulose 27:575–593 Peresin MS, Vesterinen AH, Habibi Y, Johansson LS, Pawlak JJ, Nevzorov AA, Rojas OJ (2014) Crosslinked PVA nanofibers reinforced with cellulose nanocrystals: water interactions and thermomechanical properties. J Appl Polym Sci 131(11) Perez RF, Soares OS, de Farias AMD, Pereira MFR, Fraga MA (2018) Conversion of hemicellulose-­ derived pentoses over noble metal supported on 1D multiwalled carbon nanotubes. Appl Catal B Environ 232:101–107 Pervaiz S, Qureshi TA, Kashwani G, Kannan S (2021) 3D printing of fiber-reinforced plastic composites using fused deposition modeling: a status review. Materials (Basel) 14:4520 Phanthong P, Reubroycharoen P, Hao X, Xu G, Abudula A, Guan G (2018) Nanocellulose: extraction and application. Carbon Resour Convers 1:32–43 Pires JR, Souza VG, Fernando AL (2019) Valorization of energy crops as a source for nanocellulose production–current knowledge and future prospects. Ind Crop Prod 140:111642 Plackett D, Letchford K, Jackson J, Burt HA (2014) Review of nanocellulose as a novel vehicle for drug delivery. Nord Pulp Pap Res J 29:105–118 Popa VI, Capraru AM, Grama S, Malutan T (2011) Nanoparticles based on modified lignins with biocide properties. Cellul Chem Technol 45:221 Poyraz B, Tozluoglu A, Candan Z, Demir A (2017a) Matrix impact on the mechanical, thermal and electrical properties of microfluidized nanofibrillated cellulose composites. J Polym Eng 37(9):921–931 Poyraz B, Tozluoglu A, Candan Z, Demir A, Yavuz M (2017b) Influence of PVA and silica on chemical, thermo-mechanical and electrical properties of celluclast-treated nanofibrillated cellulose composites. Int J Biol Macromol 104:384–392 Poyraz B, Tozluoglu A, Candan Z, Demir A, Yavuz M, Buyuksari U, Unal HI, Fidan H, Saka RC (2018) TEMPO-treated CNF composites: pulp and matrix effect. Fibers Polym 19(1):195–204 Prasad V, Suresh D, Joseph MA, Sekar K, Ali M (2018) Development of flax fiber reinforced epoxy composite with nano TiO2 addition into the matrix to enhance mechanical properties. Mater Today Proc 5:11569–11575 Prasanna NS, Mitra J (2020) Isolation and characterization of cellulose nanocrystals from Cucumis sativus peels. Carbohydr Polym 247:116706 Principia Partners (2002) Natural & wood fiber composites. Principiam Newsl:1–1 Pua F, Fang Z, Zakaria S, Guo F, Chia C (2011) Direct production of biodiesel from high-acid value Jatropha oil with solid acid catalyst derived from lignin. Biotechnol Biofuels 4:56 Rajinipriya M, Nagalakshmaiah M, Robert M, Elkoun S (2018) Importance of agricultural and industrial waste in the field of nanocellulose and recent industrial developments of wood based nanocellulose: a review. ACS Sustain Chem Eng 6:2807–2828 Ramesh M, Rajeshkumar L, Sasikala G, Balaji D, Saravanakumar A, Bhuvaneswari V, Bhoopathi R (2022) A critical review on wood-based polymer composites: processing, properties, and prospects. Polymers 14:589 Rangan A, Manchiganti MV, Thilaividankan RM, Kestur SG, Menon R (2017) Novel method for the preparation of lignin-rich nanoparticles from lignocellulosic fibers. Ind Crop Prod 103:152–160 Raquez JM, Habibi Y, Murariu M, Dubois P (2013) Polylactide (PLA)-based nanocomposites. Prog Polym Sci 38:1504–1542

130

M. Zor et al.

Rico-García D, Ruiz-Rubio L, Pérez-Alvarez L, Hernández-Olmos SL, Guerrero-Ramírez GL, Vilas-Vilela JL (2020) Lignin-based hydrogels: synthesis and applications. Polymers 12(1):81 Riedel U, Nickel J (2003) Seventh international conference on wood fiber-plastic composites, 19–20 May, Madison Rojo E, Peresin MS, Sampson WW, Hoeger IC, Vartiainen J, Laine J, Rojas OJ (2015) Comprehensive elucidation of the effect of residual lignin on the physical, barrier, mechanical and surface properties of nanocellulose films. Green Chem 17:1853–1866 Rueda L, Saralegi A, Fernández-d’Arlas B, Zhou Q, Alonso-Varona A, Berglund LA, Mondragon I, Corcuera MA, Eceiza A (2013) In situ polymerization and characterization of elastomeric polyurethane-cellulose nanocrystal nanocomposites. Cell response evaluation. Cellulose 20(4):1819–1828 Saito T, Brown RH, Hunt MA, Pickel DL, Pickel JM, Messman JM et al (2012) Turning renewable resources into value-added polymer: development of lignin-based thermoplastic. Green Chem 14:3295–3303 Salami MA, Kaveian F, Rafienia M, Saber-Samandari S, Khandan A, Naeimi M (2017) Electrospun polycaprolactone/lignin-based nanocomposite as a novel tissue scaffold for biomedical applications. J Med Signals Sens 7(4):228 Salimi S, Sotudeh-Gharebagh R, Zarghami R, Chan SY, Yuen KH (2019) Production of nanocellulose and its applications in drug delivery: a critical review. ACS Sustain Chem Eng 7:15800–15827 Sanna R, Fortunati E, Alzari V, Nuvoli D, Terenzi A, Casula MF, Kenny JM, Mariani A (2013) Poly (N-vinylcaprolactam) nanocomposites containing nanocrystalline cellulose: a green approach to thermoresponsive hydrogels. Cellulose 20(5):2393–2402 Sarikaya M et  al (2003) Molecular biomimetics: nanotechnology through biology. Nat Mater 2:577–585 Savov V, Antov P, Trichkov N (2021) Properties of high-density fiberboards bonded with urea-­ formaldehyde and phenol-formaldehyde resins. Innov Wood Ind Eng Des 2(20):17–26 Shah T, Gupta C, Ferebee RL, Bockstaller MR, Washburn NR (2015) Extraordinary toughening and strengthening effect in polymer nanocomposites using lignin-based fillers synthesized by ATRP. Polymer (Guildf) 72:406–412 Shojaeiarani J, Bajwa D, Shirzadifar A (2019) A review on cellulose nanocrystals as promising biocompounds for the synthesis of nanocomposite hydrogels. Carbohydr Polym 216:247–259 Sipponen MH, Henn A, Penttilä P, Österberg M (2020) Lignin-fatty acid hybrid nanocapsules for scalable thermal energy storage in phase-change materials. Chem Eng J 393:124711 Siró I, Plackett D (2010) Microfibrillated cellulose and new nanocomposite materials: a review. Cellulose 17:459–494 Song J, Rojas OJ (2013) Paper chemistry: approaching super-hydrophobicity from cellulosic materials: a review. Nord Pulp Paper Res J 28(2):216–238 Sözen E, Zor M, Aydemir D (2018) The effect of nano TiO2 and nano boron nitride on mechanical, morphological, and thermal properties of WF/PP composites. Drvna Industrija 69:13–22 Stojanovska E, Kurtulus M, Abdelgawad A, Candan Z, Kilic A (2018) Developing lignin-based bio-nanofibers by centrifugal spinning technique. Int J Biol Macromol 113:98–105 Stojanovska E, Pampal ES, Kilic A, Quddus M, Candan Z (2019) Developing and characterization of lignin-based fibrous nanocarbon electrodes for energy storage devices. Compos Part B 158:239–249 Taghiyari HR (2014) Nanotechnology in wood and wood-composite materials. J Nanomater Mol Nanotechnol 3:1–2 Taghiyari HR, Hosseini SB, Ghahri S, Ghofrani M, Papadopoulos AN (2020a) Formaldehyde emission in micron-sized wollastonite-treated plywood bonded with soy flour and urea-­ formaldehyde resin. Appl Sci 10:6709 Taghiyari HR, Tajvidi M, Taghiyari R, Mantanis GI, Esmailpour A, Hosseinpourpia R (2020b) Nanotechnology for wood quality improvement and protection. In: Husen A, Jawaid M (eds) Nanomaterials for agriculture and forestry applications. Elsevier, Amsterdam, pp 469–489

Wood Plastic Composites (WPCs): Applications of Nanomaterials

131

Tajvidi M, Gardner DJ, Bousfield DW (2016) Cellulose nanomaterials as binders: laminate and particulate systems. J Renew Mater 4:365–376 Tarrés Q, Deltell A, Espinach FX, Pèlach MÀ, Delgado-Aguilar M, Mutjé P (2017) Magnetic bionanocomposites from cellulose nanofibers: fast, simple and effective production method. Int J Biol Macromol 99:29–36 Terrett OM, Dupree P (2019) Covalent interactions between lignin and hemicelluloses in plant secondary cell walls. Curr Opin Biotechnol 56:97–104 Tian D, Hu J, Bao J, Chandra RP, Saddler JN, Lu C (2017) Lignin valorization: lignin nanoparticles as high-value bio-additive for multifunctional nanocomposites. Biotechnol Biofuels 10:192 Tian D, Hu J, Chandra RP, Saddler JN, Lu C (2017a) Valorizing recalcitrant cellulolytic enzyme lignin via lignin nanoparticles fabrication in an integrated biorefinery. ACS Sustain Chem Eng 5:2702–2710 Tong X, Shen W, Chen X, Jia M, Roux JC (2020) Preparation and mechanism analysis of morphology-­controlled cellulose nanocrystals via compound enzymatic hydrolysis of eucalyptus pulp. J Appl Polym Sci 137:48407 Tortora M, Cavalieri F, Mosesso P, Ciaffardini F, Melone F, Crestini C (2014) Ultrasound driven assembly of lignin into microcapsules for storage and delivery of hydrophobic molecules. Biomacromolecules 15:1634–1643 Tozluoglu A, Poyraz B, Candan Z, Yavuz M, Arslan R (2017) Biofilms from micro/nanocellulose of NaBH4-modified kraft pulp. Bull Mater Sci 40(4):699–710 Tozluoglu A, Poyraz B, Candan Z (2018a) Examining the efficiency of mechanic/enzymatic pretreatments in micro/nanofibrillated cellulose production. Maderas Cienc Tecnol 20(1):67–84 Tozluoglu A, Poyraz B, Mcdonald AG, Candan Z (2018b) Developing nanocellulose-based biofilms from kraft and NaBH4-modified kraft pulp. Cellul Chem Technol 52(3–4):223–237 Trache D, Hussin MH, Haafiz MM, Thakur VK (2017) Recent progress in cellulose nanocrystals: sources and production. Nanoscale 9:1763–1786 Trevisan H, Rezende CA (2020) Pure, stable and highly antioxidant lignin nanoparticles from elephant grass. Ind Crops Prod 145:112105 Turku I, Karki T (2014) Research progress in wood-plastic nanocomposites: a review. J Thermoplast Compos Mater 27:180–204 Wang Z, Xu C, Tammela P, Huo J, Strømme M, Edström K, Gustafsson T, Nyholm L (2015) Flexible freestanding Cladophora nanocellulose paper based Si anodes for lithium-ion batteries. J Mater Chem A 3:14109–14115 Wang S, Feng N, Zheng J, Yoon K, Lee D, Qu M et al (2016) Preparation of polyethylene/lignin nanocomposites from hollow spherical lignin- supported vanadium- based Ziegler–Natta journal pre-proof catalyst. Polym Adv Technol 27:1351–1354 Wang X, Song K, Ou R (2017) Effects of carbon black and titanium dioxide on ultraviolet weathering of wood flour-HDPE/lumber composites using multi-phase co-extrusion technology. Bioresources 12(3):6173–6186 Wang D, Xuan L, Han G, Wong AH, Wang Q, Cheng W (2019) Preparation and characterization of foamed wheat straw fiber/polypropylene composites based on modified nano-TiO2 particles. Compos Part A 128:1–10 Wang S, Yu S, Li J, Li S (2020) Effects of functionalized nanoTiO2 on the molecular motion in epoxy resin-based nanocomposites. Materials 13:1–10 Wang F, Ouyang D, Zhou Z, Page SJ, Liu D, Zhao X (2021) Lignocellulosic biomass as sustainable feedstock and materials for power generation and energy storage. J Energy Chem 57:247–280 Watanabe A (2012) History of wood plastics. Wood Ind 67:466–469 Weichelt F, Emmler R, Flyunt R, Beyer E, Buchmeiser MR, Beyer M (2010) ZnO-based UV nanocomposites for wood coatings in outdoor applications. Macromol Mater Eng 295:130–136 Wijaya CJ, Ismadji S, Gunawan S (2021) A review of lignocellulosic-derived nanoparticles for drug delivery applications: lignin nanoparticles, xylan nanoparticles, and cellulose nanocrystals. Molecules 26:676

132

M. Zor et al.

Xiong F, Wu Y, Li G, Han Y, Chu F (2018) Transparent nanocomposite films of lignin nanospheres and poly (vinyl alcohol) for UV-absorbing. Ind Eng Chem Res 57:1207–1212 Xu T, Jiang Q, Ghim D, Liu KK, Sun H, Derami HG, Wang Z, Tadepalli S, Jun YS, Zhang Q (2018) Catalytically active bacterial nanocellulose-based ultrafiltration membrane. Small 14:1704006 Xu J, Xu JJ, Lin Q, Jiang L, Zhang D, Li Z, Ma B, Zhang C, Li L, Kai D, Yu HD, Loh XJ (2021) Lignin-incorporated nanogel serving as an antioxidant biomaterial for wound healing. ACS Appl Bio Mater 4:3–13 Yadav SM, Yusoh KB (2015) Mechanical and physical properties of wood-plastic composites made of polypropylene, wood flour and nanoclay. Int J Agric For Plantat 1:52–58 Yan Z, Song B, Fang G, Wu T, Chen N, Zhao M, Zou X, Liao G (2021) Bringing material concepts into conventional biorefineries: considerations of sources, preparations, and applications of lignin nanomaterials. ACS Sustain Chem Eng 9:10403–10423 Yang L, Zhang HY, Yang Q, Lu DN (2012) Bacterial cellulose–poly (vinyl alcohol) nanocomposite hydrogels prepared by chemical crosslinking. J Appl Polym Sci 126(S1):E245–E251 Yang W, Fortunati E, Dominici F, Kenny JM, Puglia D (2015a) Effect of processing conditions and lignin content on thermal, mechanical and degradative behavior of lignin nanoparticles/polylactic (acid) bionanocomposites prepared by melt extrusion and solvent casting. Eur Polym J 71:126–139 Yang W, Kenny JM, Puglia D (2015b) Structure and properties of biodegradable wheat gluten bionanocomposites containing lignin nanoparticles. Ind Crop Prod 74:348–356 Yang W, Fortunati E, Dominici F, Giovanale G, Mazzaglia A, Balestra GM et al (2016a) Synergic effect of cellulose and lignin nanostructures in PLA based systems for food antibacterial packaging. Eur Polym J 79:1–12 Yang W, Owczarek JS, Fortunati E, Kozanecki M, Mazzaglia A, Balestra GM, Kenny JM, Torre L, Puglia D (2016b) Antioxidant and antibacterial lignin nanoparticles in polyvinyl alcohol/ chitosan films for active packaging. Ind Crop Prod 94:800–811 Yang W, Rallini M, Wang DY, Gao D, Dominici F, Torre L, Kenny JM, Puglia D (2018) Role of lignin nanoparticles in UV resistance, thermal and mechanical performance of PMMA nanocomposites prepared by a combined free-radical graft polymerization/masterbatch procedure. Compos Part A Appl Sci Manuf 107:61–69 Yiamsawas D, Baier G, Thines E, Landfester K, Wurm FR (2014) Biodegradable lignin nanocontainers. RSC Adv 4:11661–11663 Yildirim M, Candan Z (2021) Performance properties of particleboard panels modified with nanocellulose/boric acid. Bioresources 16:1 Yildirim M, Negawo TA, Kilic A, Candan Z (2020) Development and characterization of hybrid composites from sustainable green materials. Green Mater:1–10 Yildirim M, Candan Z, Gonultas O (2021) Chemical performance analysis of nanocellulose/boron compounds reinforced hybrid UF resin. Green Mater:1–8 Yoo HD, Kim D, Paek SH (2012) Plant cell wall polysaccharides as potential resources for the development of novel prebiotics. Biomol Ther 20(4):371 Younas M, Noreen A, Sharif A, Majeed A, Hassan A, Tabasum S et al (2019) A review on versatile applications of blends and composites of CNC with natural and synthetic polymers with mathematical modeling. Int J Biol Macromol 124:591–626 Yu Y, Jiang Z, Wang G, Song Y (2010) Growth of ZnO nanofilms on wood with photostability. Holzforschung 64:385–390 Yu J, Zhu Y, Ma H, Liu L, Hu Y, Xu J, Wang Z, Fan Y (2019) Contribution of hemicellulose to cellulose nanofiber-based nanocomposite films with enhanced strength, flexibility and UV-blocking properties. Cellulose 26(10):6023–6034 Zhang X, Liu W, Liu W, Qiu X (2020a) High performance PVA/lignin nanocomposite films with excellent water vapor barrier and UV-shielding properties. Int J Biol Macromol 142:551–558 Zhang X, Morits M, Jonkergouw C, Ora A, Valle-Delgado JJ, Farooq M, Ajdary R, Huan S, Linder M, Rojas O, Sipponen MH, Osterberg M (2020b) Threedimensional printed cell culture model based on spherical colloidal lignin particles and cellulose nanofibril-alginate hydrogel. Biomacromolecules 21(5):1875–1885

Wood Plastic Composites (WPCs): Applications of Nanomaterials

133

Zhao Y, Gao G, Liu D, Tian D, Zhu Y, Chang Y (2017) Vapor sensing with color-tunable multilayered coatings of cellulose nanocrystals. Carbohydr Polym 174:39–47 Zhao W, Simmons B, Singh S, Ragauskas A, Cheng G (2016) From lignin association to nano-/ micro-particle preparation: extracting higher value of lignin. Green Chem 18(21):5693–5700 Zhong Y, Poloso T, Hetzer M, De Kee D (2007) Enhancement of wood/polyethylene composites via compatibilization and incorporation of organoclay particles. Polym Eng Sci 47:797–803 Zhou H, Li W, Hao X, Zong G, Yi X, Xu J, Ou R, Wang Q (2022) Recycling end-of-life WPC products into ultra-high-filled, high-performance wood fiber polyethylene composites a sustainable strategy for clean and cyclic processing in the WPC industry. J Mater Res Technol 18:1–14 Zhu H, Luo W, Ciesielski PN, Fang Z, Zhu JY, Henriksson G, Himmel ME, Hu L (2016) Wood-­ derived materials for green electronics, biological devices, and energy applications. Chem Rev 116:9305–9374 Zhu H, Fang Z, Preston C, Li Y, Hu L (2014) Transparent paper: fabrications, properties, and device applications. Energy Environ Sci 7(1):269–287 Zolin L, Destro M, Curtil D, Chaussy D, Penazzi N, Beneventi D, Gerbaldi C (2014) Flexible cellulose-­ based electrodes: towards eco-friendly all-paper batteries. Chem Eng Trans 41:361–366 Zor M, Tankut N, Gardner DJ, Yazici H (2016) Feasibility of using foamed styrene maleic anhydride (SMA) co-polymer in wood based composites. Drvna Industrija 67:399–407

Nanomaterials to Improve Properties in Wood-Based Composite Panels Viktor Savov

Contents 1  Introduction 2  Improvement of the Properties of Wood-Based Composite Panels by Nanomaterials 3  Conclusion References

 135  137  149  150

1 Introduction In the contemporary dynamic world, the development of modern materials is fundamental to human society. Production of wood-based composite panels is one of the developing woodworking industries with a steady growth rate of production quantity (FAO Stat.), that is due to the diverse application of these materials in the industry and everyday life. In this type of material, trim and lower quality wood can be used as raw material. Therefore, these materials do not threaten the development of forests but, on the contrary, lead to the development of forest resources (Igaz et al. 2016). Concerning the environmental friendliness of wood-based composite panels, significant progress has been made in recent years to reduce formaldehyde emissions and to utilize secondary, waste, bio-based products as binders for the boards (Valyova et  al. 2017; Ružiak et  al. 2017; Ghahri and Pizzi 2018; Ghahri et  al. V. Savov (*) Department of Mechanical Wood Technology, Faculty of Forest Industry, University of Forestry, Sofia, Bulgaria e-mail: [email protected]

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 H. R. Taghiyari et al. (eds.), Emerging Nanomaterials, https://doi.org/10.1007/978-3-031-17378-3_5

135

136

V. Savov

2018; Pizzi 2019; Pizzi and Papadopulus 2020; Antov et al. 2021a, b). The next considerable impetus in the technology and development of wood-based panels is expected to incorporate nanomaterials and to introduce nanotechnology in woodbased panels production (Gao et  al. 2015; Bayani et  al. 2019; Lu et  al. 2019; Esmailpour et al. 2020; Liu et al. 2020). In this way, wood-based composite panels will be able to meet the growing demands of consumers in terms of waterproofness, strength, thermal conductivity, electrical resistance, biostability of materials and so on (Taghiyari and Schmidt 2014; Zhang et  al. 2020; Vahabi et al. 2022). As mentioned in recent years, there has been an increased use of wood and natural fibres of plant origin to produce wood-based composite panels used both in-­ home and industry—automotive, housing, aircraft, etc., that is because wood and its primary component, namely celluloses, are reproducible materials in nature and the constant depletion of non-renewable organic raw materials such as oil, gas and others (Ninikas et  al. 2021). A significant amount of research is related to polymer composites from different materials, synthetic polymers and those using different binders. Polymers can be made of wood, vegetable fibres, wood flour and sawdust. Wood-based composite panels are particularly interested as they can be with specific properties and various applications. Nanoscience and nanotechnology provide unique opportunities to create revolutionary new combinations of materials based on wood and wood derivatives with specific properties (Taghiyari et  al. 2015, 2017a, b; Papadopoulos and Taghiyari 2019; Shi and Avramidis 2021; Slabohm et al. 2022; Lubis et al. 2022). These new materials have significant advantages in quality and unique properties over the classic ones. (Taghiyari et al. 2013a, 2020b). According to the definition of EC, nanomaterials are natural, incidental or manufactured materials containing particles in an unbound state or as an aggregate or as an agglomerate and where, for 50% or more of the particles in the number size distribution, one or more external dimensions is in the size range 1/100 nm (European Commission – Environment n.d.). By derogation from the above, fullerenes, graphene flakes and single-wall carbon nanotubes with one or more external dimensions below 1 nm should be considered nanomaterials. The in-depth study of the physiochemistry of the nanoscale state of ligand nanoparticles has led to increased stability of nanocomposites and control of reversible transitions in these systems. In this aspect, polymers, including natural ones, are essential for stabilizing the nanoscale state. However, the synthesis of nanocomposites is complex and multistage. This chapter provides an overview, without claiming to be exhaustive, of the main directions and achievements in using nanomaterials for wood-based composite panels.

Nanomaterials to Improve Properties in Wood-Based Composite Panels

137

2 Improvement of the Properties of Wood-Based Composite Panels by Nanomaterials Wood-based composite panels are usually described as a wide range of products that combine wood elements held together by a binder (Hosseinpourpia et al. 2019; Jasmani et  al. 2020; Kristak et  al. 2022). Among the advantages of wood-based composites are that they can be designed for specific qualities or performance requirements at different thicknesses, degrees and sizes. Wood composites are manufactured to take advantage of the natural strength characteristics of wood (and sometimes lead to more significant structural strength and stability than ordinary wood). On the other hand, wood composites also have disadvantages, requiring more primary energy for production than solid wood. Therefore, wood composites are not suitable for outdoor use as they can absorb water and are more susceptible to distortion caused by moisture than solid wood. The adhesives are used to release toxic formaldehyde into the final product. Nanotechnologies can be used to improve the quality of wood-based composites to meet the growing demand for existing products and new products to be used in new applications. The main disadvantages of wood are its sensitivity and biodegradability by microorganisms and dimensional instability when subjected to different moisture content. They are mainly due to the basic polymers of the cell wall and their great abundance of hydroxyl groups (OH) (Papadopoulos 2010). Wood is naturally hygroscopic, and the moisture absorption from wood is directly related to the exposed surface. The addition of inorganic nanoparticles to wood composites has been reported to improve the antimicrobial properties of composites. Zinc oxide (ZnO) nanoparticles exhibit good antimicrobial activity. These nanoparticles were added to melamine-­ urea formaldehyde (MUF) resin before being used to produce particleboard (Reinprecht et al. 2018). The findings show an increase in the resistance of particleboards against the gram-positive bacterium Staphylococcus aureus, the gram-­ negative bacterium Escherichia coli, the moulds Aspergillus niger and Penicillium brevicompactum, as well as the fungus Coniophora puteana. Silver nanoparticles, well-known biocidal additives, also show similar antibacterial and antimould effects when applied to melamine-laminated wood particleboard surfaces (Nosal and Reinprecht 2019). The combination of nanoscale oxide and an alkane surfactant has also been confirmed to improve treated plywood samples’ water and termite resistance (Gao and Du 2015). The modified starch-based adhesive has been studied as another option to increase the rot resistance of particleboards. Particleboards with modified PVA/palm oil starch added with nanosilicon oxide (SiO2) and boric acid are more resistant to rot than particleboard associated with their natural starch (Abd Norani et al. 2017). The addition of nano-SiO2 and boric acid as waterproof and antifungal agents, respectively, prevented the activity of the microorganism in the final wood-based composite panel. The production of wood-­ based composite panels can be improvised by developing methods to reduce the curing time of the resin during hot-pressing, which could speed up production or improve the overall quality of the board. The heat transfer that affects the pressing

138

V. Savov

time of a wood-based composite panel varies depending on the thickness, hot-­ pressing temperature, closing speed and substrate moisture distribution. Adding ZnO nanoparticles increases the heat transfer in the centre of the particleboards during hot-pressing, leading to a higher degree of resin hardening and improving the physical and mechanical properties of the panels (Silva et  al. 2019). High-­ conductivity nanoparticles such as multi-walled carbon nanotubes (CNTS) and alumina (Al2O3) have also been shown to improve the thermal and mechanical properties of medium-density fibreboards (Gupta et  al. 2018). The study also reported that although activated carbon nanoparticles did not significantly affect the physical and mechanical properties of the panels, they had a faster effect on hardening urea-formaldehyde (UF) resin and reducing formaldehyde emissions compared to the other two nanofillers. Mantanis and Papadopoulos have studied the potential for improving the thickness swelling of the wood-based panels by applying a new nanotechnology compound (Mantanis and Papadopoulos 2010b). The study shows that the application of SurfaPore™, an aqueous wood waterproof repellent agent, led to a significant improvement in the thickness swelling of the panels. That nanomaterial is a water-­ based formula designed to harness the power of nanotechnology to reduce the absorption of wood surfaces. The formula consists of three nanoparticles specially designed to penetrate the wood. The finest nanoparticles are designed to penetrate capillaries and bind to the hydroxyl groups of the cellulose. Larger nanoparticles penetrate to the appropriate depth and react with wood polymers. Finally, the formulation is completed with a nano-emulsion of wax, designed to provide surface protection. Three types of wood-based composite panels were used: particleboards, medium-density fibreboards (MDF) and oriented strand board (OSB). The density of the boards was 0.66, 0.70 and 0.63 gr/cm3 for particleboards, MDF and OSB, respectively, while the thickness was 18, 16 and 15 mm. The study proves that applying nanotechnology has improved dimensional stability. Statistical analysis revealed that the improvement was significant at a probability level of 0.05 for all tested panels. However, the degree of thickness swelling reduction was not the same for the three panels tested. More significant improvement was observed for MDF (13.6%), lower for OSB (9.9%), and an intermediate value was found for particleboards (12.1%). The higher improvement observed in fibreboards can be explained because MDF is a harder and more homogeneous panel than particleboards and OSB. Therefore, small nanoparticles can penetrate the panel more efficiently, resulting in higher protection against moisture. On the other hand, the higher pressure required to consolidate the OSB mat leads to an increased spring, partly explaining the lower improvement of thickness swelling observed in this study. Results clearly show that the extended period does not significantly affect dimensional stability. It was impossible to find comparable data in the literature on the use of such compounds to improve the dimensional stability of wood-based panels. From the data presented in this study, it can be concluded that nanotechnology compounds may be an option to reduce the thickness swelling of wood-based composite panels.

Nanomaterials to Improve Properties in Wood-Based Composite Panels

139

The metal-containing nanomaterials, particularly polymer nanocomposites, are currently of great interest due to their unique physical and chemical properties and application possibilities (Miyafuji and Saka 1997; Chen et al. 2009; Sun et al. 2010; Mantanis and Papadopoulos 2010a; Nenkova et al. 2011; Salari et al. 2013; Palanti et  al. 2012; Petya et  al. 2014; Wang et  al. 2015; Wu et  al. 2019; Papadopoulos et al. 2019). Electrically conductive polymeric and fibre materials with microwave absorption properties can be precious for practical application (Nenkova et  al. 2010, 2012; Garvanska et al. 2012). By adding mineral fillers, metals and fibres to polymers, composites with improved strength, heat resistance and other specific properties can be fabricated (Candan and Akbulut 2014; Chang et al. 2015; Chen et al. 2021). In recent years, significant progress has been made by creating nanocomposite materials with a highly developed inner surface compared to traditional composites and correspondingly improved performance with a low percentage of filler (Chen et al. 2021). A significant advantage of nanocomposite materials is that the technologies and techniques used to obtain them are not complicated and could be relatively cheap (Hu et al. 2013; Ismita and Lokesh 2017; Gul et al. 2021). Many studies are also conducted in hybrid organic/inorganic nanocomposites to produce materials with new properties other than the starting materials. Therefore, nanocomposites provide excellent opportunities for new applications of lightweight reinforcement components. It should be noted that nanocomposites make it possible to fabricate products with superconducting properties (Dragnevska et al. 2011). Studies in this direction are promising and can lead to the development of new materials with unique properties. The conducted studies and their results showed the relevance, importance and need for in-depth research on creating a new type of metal-containing nanocomposite materials with high electrical conductivity for use in technology and household as products for electromagnetic wave protection. The nanomaterials in wood-based composite panels could include metal-­ containing nanocomposites based on copper sulphide complexes, which are coordinatively related to the lignocellulose matrix of wood materials. On that base could be developed a modified with nanomaterials fibreboards with specific properties such as electrical conductivity, bactericidal, microbial, microbial–mechanical properties with high content of the wood component. The theoretical basis for developing methods for the production of cuprous sulphide lignocellulosic nanocomposites is based on the fact that cuprous sulphide as an additive to polymers gives high electrical conductivity as an indirect indicator of relevant dielectric losses, leads to new materials with microwave absorption properties. A significant increase in the effect is achieved if the cupro-sulphide is in the nanostate and coordinated as a network in the polymer lignocellulose matrix. In this sense, the development of methods is based on chemical modification of different lignocellulosic materials with water solutions of the copper-containing compound and sulphur-containing reducer in appropriate quantities and ratios at specific process parameters like temperature and hot-pressing time. Under such conditions, an

V. Savov

140

opportunity is created for a process of reduction of copper to cuprous and subsequent coordinative deposition in the lignocellulose matrix. The research conducted by Dragnevska et al. with a three-component reduction system unequivocally shows that if wood fibres specific in composition and structure are used, cuprous sulphide-containing lignocelluloses with only a sulphur-­ containing reducer can be obtained, thus avoiding the use of an additional reducing agent (e.g. glyoxal) which it would be very profitable from an environmental point of view (Dragnevska et al. 2011). These data determine the direction of the following research related to developing and optimizing a method for modification with a two-component reduction system CuSO4-Na2S2O3. The scheme of the oxidation-reduction process is:

Cu 2  1e   Cu 1



2S2  2.2e   2S4



2CuSO 4  2 Na 2 S2 O3  Cu 2 S  2 Na 2 SO 4  3SO

The study showed that in the infrared spectra of modified wood flour and fibres, a peak was observed at ~400 cm−1, characteristic of the metal-oxygen bond (Fig. 1). This connection is probably due to the coordination of copper ions with oxygen atoms from the OH groups of the cellulose and the aromatic nucleus of the lignin macromolecule. Coordinate binding of vanillin via the oxygen methoxy atom and the deprotonated hydroxyl oxygen atom in the aromatic nuclei was observed that confirms the binding of copper ions to lignin (Fig. 2). Lignocellulosic materials may also exhibit physical adsorption to copper ions (Fig. 3).

Fig. 1  Infrared spectra: (a) unmodified-1 and modified-wood flour with a three-component system in the amount of 40% of the flour; (b) unmodified-1 and modified-2 wood fibres with a two-­ component system in the amount of 30% straight fibres; (c) unmodified-1 and modified-2 with a two-component wood fibre system in the amount of 40% of the fibres (Dragnevska et al. 2011)

Nanomaterials to Improve Properties in Wood-Based Composite Panels

141

Fig. 2  Copper sulphide cellulose nanocomposites (Dragnevska et al. 2011) Fig. 3  Copper sulphide lignin nanocomposites (Dragnevska et al. 2011)

To visualize the morphology and determine the size and shape of the obtained cuprous sulphide particles, some studies were carried out. It was found that the fibres were covered with clusters of the formed cuprosulphide nanoparticles. It has been observed that they are below 100 nm, and their shape varies from spherical to elliptical. The main conclusions of this study are that the treatment with a three-­ component reduction system CuSO4:Na2S2O3:(CHO)2 by intermittent method at standard pressure and temperature 90 °C is particularly promising for the modification of waste cellulose fibres and, to a lesser extent, for lignocellulosic material under the form of wood flour. The modification method with a two-component CuSO4 reduction system: Na2S2O3, is preferred for wood fibres. The optimal parameters of the modification process of wood fibres with a two-component system in saturated steam conditions are specified—40% of a two-component system compared to the wood material; modulus 1:6 and ratio of CuSO4:Na2S2O3 = 1:2. The data from the IR spectra give grounds to claim the coordination of copper ions with oxygen atoms from the OH groups of cellulose and the aromatic nucleus of the lignin macromolecule. The modified fibrous materials obtained in this study

142

V. Savov

can be used to make wood-polymer composites with specific properties for electromagnetic wave protection. A study was also performed for the modification of the wood fibre material with the three-component reduction system under the following predetermined conditions: ratios of the components CuSO45H2O:Na2S2O35H2O:(CHO)2 = 1.6:1.4:1 in 40% of the lignocellulosic material in module 1:12, temperature 90 °C for 30 min. The modification of the wood fibre material with the two-component reduction system was initially performed in a saturated steam thermal chamber at 110  °C for 30 min at ratios of CuSO4 5H2O:Na2S2O3 5H2O = 1:1 and 1:2 components in 20% and 40% relative to the lignocellulosic material at a constant modulus M = 1:12. The obtained results are satisfactory in reducing the specific electrical resistance by about two orders of magnitude, but with a significant content of copper and sulphur in wastewater. Therefore, the modification process was further optimized at a lower modulus—M = 1:6, a ratio of CuSO4 5H2O:Na2S2O3 5H2O = 1:2 and variation of the content of the components, relative to the wood fibre material, in the range of 20% to 40%. The results of the measurements have shown that (1) the sulphur content in the modified wood fibres is almost zero when using a three-component system, which speaks of a substantial reduction process. When using wood fibres characterized by a specific structure, cuprous sulphide-containing lignocelluloses can be obtained only with a sulphur-containing reducing agent, which would be economically and environmentally advantageous. With a low modulus of modification, the amount of wastewater is meagre without disturbing the ordinary course of the modification process. The data showed that the electrical resistance values decreased by approximately two orders of magnitude in the samples modified by 20%, 30% and 40%, which significantly improved the electrical conductivity of the treated wood. In 40% of the two-component system to the wood material, an optimal ratio between the modifying components (copper: sulphur) was achieved compared to the samples obtained at 20% and 30%. It should be pointed out that with the application of nanomaterials in wood-based composite panels, the antibacterial and antimould properties of these materials can be significantly improved (Zhang et al. 2008; Lin et al. 2008; Mantanis et al. 2014; Taghiyari 2014; Okyay et al. 2015; Xie et al. 2018; Li et al. 2020). A study was also conducted to evaluate the antibacterial properties of Cu-modified fibreboard panels (Nenkova et al. 2011). Five types of wood-based composite panels with different Cu content were used for the analysis. It was found that the growth of Bacillus subtilis is slower; i.e., copper ions inhibit G + bacteria to a greater extent than Escherichia coli K12 (G-bacteria). The obtained results show that the modified cuprous sulphide fibreboards have a more substantial antibacterial effect against G + than G-bacteria due to the different structures of the bacterial cell wall. In a study by Lin et al., Ag/TiO2 nanocomposites of solid wood were fabricated by ultrasonic impregnation and vacuum impregnation methods (Fig. 4). The aim is to improve the antimould properties of the material (Lin et al. 2020). The samples were characterized by field emission scanning electron microscopy (FESEM), energy dispersion spectroscopy (EDS), Fourier transforms infrared

Nanomaterials to Improve Properties in Wood-Based Composite Panels

143

Fig. 4  Mould infection of (a) original wood, (b) wood sample impregnated with Ag/TiO2 nanoparticles via ultrasound (UW) and (c) wood sample impregnated with Ag/TiO2 nanoparticles via vacuum assistance (VW) (Lin et al. 2020)

spectroscopy (FTIR), mercury penetration porosimetry (MIP) and water contact angles (WCAs). The antimould properties of Ag/TiO2 wood-based nanocomposites have been improved 14 times compared to those of the original wood. Nano-Ag/ TiO2, which was impregnated in the trachea and attached to the cell walls, was able to form a two-stage coarse structure and reduce the number of hydroxyl functional groups on wooden surfaces (Fig. 5). The resulting decrease in wood‘s hydrophobic and equilibrium moisture content (EMC) destroys the moisture necessary for mould survival. Ag/TiO2 is deposited in the wood’s pores, reducing the number and volume of pores and blocking infection with mould. Thus, the antimould properties of the wood/AgO TiO2 nanocomposite were improved by cutting out the water source and blocking the mould infection pathway. In conclusion of that research, wood-based Ag/TiO2 nanocomposites with antimould functions have been successfully prepared by ultrasonic impregnation and vacuum impregnation. Nano-Ag/TiO2 can form a two-stage rough structure on wooden surfaces and introduce long-chain alkanes to make the wood hydrophobic,

144

V. Savov

Fig. 5 Nano-Ag/TiO2 prevented wood infection by mould (Lin et al. 2020)

Fig. 6  γ-(2,3-Epoxypropoxy) propytrimethoxysilane (KH560) bonding the wood surfaces (Lin et al. 2020)

thus destroying the moist environment in the wood, which allows mould to survive. At the same time, as mentioned, Ag/TiO2 is deposited in the pores, reducing their number and total volume and blocking the path of infection with mould. That study revealed the antimould mechanism of Ag/TiO2 wood-based nanocomposites in terms of moisture content and infection pathway and potentially provided a viable path for wood-based nanocomposites with antimould properties (Fig. 6). Sepiolite can also be successfully used as a nanomaterial for improving the properties of wood-based composite panels (Olivato et al. 2017; Li et al. 2019). A study by Taghiyari et al. has improved the thermal conductivity of oriented strand lumber (OSL) using sepiolite (Taghiyari et al. 2020a) (Fig. 7). A problem with engineered wood products, such as OSL, is the material’s low thermal conductivity, which

Nanomaterials to Improve Properties in Wood-Based Composite Panels

145

Fig. 7  Flow diagram of resin–sepiolite mixture preparation (Taghiyari et al. 2020a)

prevents the rapid transfer of heat to the core of the composite. The cited study aimed to investigate the effect of sepiolite on a nanoscale with an aspect ratio of 1:15, mixed with urea-formaldehyde resin (UF) and its impact on the thermal conductivity of the end panel (Fig. 8). Sepiolite was mixed with UF resin for 20 min before spraying on wooden strips in a rotating drum. Ten percent sepiolite was added to the resin. OSL panels with two resin contents, namely 8% and 10%, were produced. The temperature was measured in the central part of the mat at intervals of 5 s using a digital thermometer. The coefficient of thermal conductivity of OSL samples is calculated based on Fourier’s law of thermal conductivity. Regarding the fact that the improved thermal conductivity will eventually turn into more efficient resin polymerization, the hardness of the panel was measured at different depths of penetration of the Janka ball to determine how the improved conductivity affects the hardness of the produced composite panels. Measurement of the core temperature in OSL panels revealed that panels treated with sepiolite with 10% resin content had a higher core temperature than those containing 8% resin. In addition, the addition of sepiolite was found to increase the thermal conductivity of OSL panels made with 8% and 10% resin content by 36% and 40%, respectively. The study shows that the addition of sepiolite significantly increases the hardness values at all depths of penetration. The hardness increases with increasing sepiolite content. Given that the amount of sepiolite content is meagre and therefore cannot physically affect the increase in hardness, the significant increase in hardness values is due to the improved thermal conductivity of the panels and the subsequent, more complete curing of the resin. Hardness values at five penetration depths were measured to verify the effect of improved thermal conductivity on at least one mechanical property. Measurement of the core temperature in OSL revealed that panels treated with sepiolite with 10% resin content had a higher core temperature than those containing 8% resin. The results show a significant increase in the thermal conductivity of the panels treated with sepiolite. The increased thermal conductivity is converted

146

V. Savov

Fig. 8  SEM image showing sepiolite nanostrands (Taghiyari et al. 2020a, b)

into more effortless heat transfer to the core of the mats, which ultimately increases the hardness values. Given that the amount of sepiolite used in the panels is meagre and therefore cannot physically affect the increase in hardness, the significant increase in hardness is due to improved thermal conductivity and subsequent more complete curing of the resin. However, additional specific resin curing studies should be performed to clarify why the effect of sepiolite on hardness values is not comparable to other nanofillers. A significant positive direct relationship was found between accelerated heat transfer versus hardness values at higher penetration depths. As the results show that an adhesive content of 8% and 10% does not significantly affect the hardness of the control OSL panels (panels without sepiolite content), a lower adhesive content of 8% was recommended for the saving industry. Lowering the resin content will result in a more competitive price. However, a higher sepiolite content is recommended to achieve maximum hardness values in panels treated with sepiolite. Nanocomposites can also be used to accelerate the hot-pressing process in the production of wood-based composite panels. For example, in a study by Taghiyari et al. 2013b, the effect of silver nanoparticles on the rate of heat transfer to the core of a medium-sized fibre substrate was investigated (Fig. 9). In this study, an aqueous

Nanomaterials to Improve Properties in Wood-Based Composite Panels

147

Fig. 9  SEM micrograph showing silver nanoparticles scattered all over the fibres (Taghiyari et al. 2013b)

suspension of a nanosilver 400 ppm was used at three levels of consumption of 100, 150 and 200 mL/kg based on dry fibres (Taghiyari et al. 2013b). The results were compared with control MDF panels. The size range of silver nanoparticles is 30–80 nm. The results show that nanoparticles‘uniform distribution throughout the MDF matrix contributes to faster heat transfer to the core. As for the loss of moisture content of the mat after the first 3–4 min of hot pressing, the core temperature decreased slightly in the control panels. However, the heat transfer property of silver nanoparticles contributed to maintaining the core temperature relatively constant. The nanosilver suspension was applied at three levels of consumption of 100, 150 and 200 mL/kg based on the dry fibres. The results proved a significantly higher heat transfer rate to the substrate’s core in NS-treated panels. It has been found that some of the improved physical and mechanical properties in nanosilver-treated composite panels reported in previous studies are related to better resin polymerization in the central part of the composite panels due to the high thermal conductivity of metal nanoparticles. However, the high heat transfer rate is also due to the depolymerization of resin bonds in the surface layers of the panels. Therefore, it can be concluded that the addition of metal nanoparticles to increase the heat transfer rate to the core of composite mats does not necessarily improve all physical and mechanical properties; in addition, the optimal consumption of metal nanoparticles in wood-based panels depends on the temperature of hot pressing, the duration of hot pressing, the thermal conductivity of metal nanoparticles and the type and density of composite panels. Nanomaterials can be used to improve the thermal conductivity of wood-based composite panels. A study by Taghiyari et al. (2014) found an effect of improving the thermal conductivity of nano-wollastonite (NW) on the properties of MDF

148

V. Savov

(Fig. 10). In this study, nanowollastonite was applied at 2, 4, 6 and 8 g/kg, based on the dry weight of sawdust, and compared with control samples (Taghiyari et  al. 2014). The size range of wollastonite was from 30 to 110 nm. The results show that NW significantly increases thermal conductivity. Increased thermal conductivity leads to better curing of the resin. Therefore, the mechanical properties have been improved considerably. In addition, the formation of bonds between wood fibres and wollastonite contributes to the strengthening of MDF. The NW content of 2 g/ kg does not significantly improve the overall properties and therefore cannot be recommended to the industry. As the properties of NW-6 and NW-8 are very similar, an NW content of 6 g/kg can be recommended to the industry to improve the properties of MDF panels significantly. Taghiyari et al. (2020b) studied the shear strength of three types of heat-treated solid wood (beech, poplar and fir) associated with NW-reinforced polyvinyl acetate (PVA) adhesive (Taghiyari et al. 2020b) (Fig. 11). The specimens were heat-treated at 165  °C and 185  °C and then bonded with PVA reinforced with 5% and 10% NW. The results show that the shear strength is significantly dependent on the density of the samples. Heat treatment substantially reduces the shear strength of the bonded specimens. That is due to several factors, such as a reduction in polar groups in the cell wall, increased cell wall hardness after heat treatment and decreased wettability of the treated wood. However, NW acts as a reinforcing agent or expander in the complex and ultimately improves the shear strength of the bond. In addition, functional density theory (DFT) has proven the formation of a bond between the calcium atoms in NW and the hydroxyl groups of cell wall polymers. The overall results show the potential of NW to improve the bond strength of heat-treated wood. Promising results were also reported for graphene to improve shear strength of PVA resin (Taghiyari et al. 2022).

Fig. 10  SEM image showing nano-wollastonite (arrow) on wood fibre (Taghiyari et al. 2014)

Nanomaterials to Improve Properties in Wood-Based Composite Panels

149

Fig. 11  Schematic representation of bond formation between calcium atoms of NW and oxygen atoms of cell wall cellulose chains (Taghiyari et al. 2020b)

Nano-wollastonite can be used to improve other properties of wood-based composite panels (Taghiyari et al. 2017b, 2021).

3 Conclusion The presented studies in this chapter unequivocally outlined the significant advantages of nanotechnology and nanomaterials as a way for the present wood-based composite panel industry to step up to the next level of development. It has been found that metal and mineral nanomaterials can significantly improve the heat transfer coefficient of wood carpets during production and the wood panels themselves. That will accelerate production cycles, leading to reduced production costs and significant new applications for this type of materials. New methods have been developed to fabricate wood-based composite panels with nanomaterials, which have a specific role in electromagnetic and wave protection. The significant advantages of wood panels with nanomaterials in fabricated products with increased biostability and antibacterial protection were also outlined. Nanomaterials can also be successfully used to produce wood panels with increased waterproofness and dimensional stability. The presented studies have shown that the introduction of materials in the production of wood-based panels is inevitable and only a matter of time. Of course,

150

V. Savov

for this to become a widespread production practice, the routine and rigidity of wood panel manufacturers must first be overcome.

References Abd Norani K, Hashim R, Sulaiman O, Hiziroglu S, Ujang S, Noor W et al (2017) Biodegradation behaviour of particleboard bonded with modified PVOH/oil palm starch and nano silicon dioxide. Iran J Energy Environ 8(4):269–273 Antov P, Savov V, Krišták L, Réh R, Mantanis GI (2021a) Eco-friendly, high-density fiberboards bonded with urea-formaldehyde and ammonium lignosulfonate. Polymers 13(2):220 Antov P, Savov V, Trichkov N, Krišťák Ľ, Réh R, Papadopoulos AN, Taghiyari HR, Pizzi A, Kunecová D, Pachikova M (2021b) Properties of high-density fiberboard bonded with urea–formaldehyde resin and ammonium lignosulfonate as a bio-based additive. Polymers 13(16):2775 Bayani S, Taghiyari HR, Papadopoulos AN (2019) Physical and mechanical properties of thermally-­modified beech wood impregnated with silver nano-suspension and their relationship with the crystallinity of cellulose. Polymers 11(10):1538 Candan Z, Akbulut T (2014) Nano-engineered plywood panels: performance properties. Compos Part B 64:155–161 Chang H, Tu K, Wang X, Liu J (2015) Fabrication of mechanically durable superhydrophobic wood surfaces using polydimethylsiloxane and silica nanoparticles. RSC Adv 5:30647–30653 Chen F, Yang X, Wu Q (2009) Antifungal capability of TiO2 coated film on moist wood. Build Environ 44(5):1088–1093 Chen C, Berglund L, Burgerd B, Hu L (2021) Wood nanomaterials and nanotechnologies. Adv Mater 33(28):2006207 Dragnevska M, Velev P, Nenkova S, Garvanska R (2011) Development of a continuous method for production of copper-sulphide wood-polymer plate nanocomposite materials. J Univ Chem Technol Metall 46(4):349–356 Esmailpour A, Taghiyari HR, Hosseinpourpia R, Adamopoulos S, Zereshki K (2020) Shear strength of heat-treated solid wood bonded with polyvinyl-acetate reinforced by nanowollastonite. Wood Res 65(2):183–194 European Commission  – Environment. (n.d.). Available at: https://ec.europa.eu/environment/ chemicals/nanotech/faq/definition_en.htm. Last accessed 16 Apr 2022 FAO Stat. Forestry Production and Trade, [online] Available at: https://www.fao.org/faostat/ en/#data/FO. Accessed Mar 2022 Gao W, Du G (2015) Physico-mechanical properties of plywood bonded by nano cupric oxide (CuO) modified pf resins against subterranean termites. Maderas Cienc Tecnol 17(1):129–138 Gao L, Lu Y, Zhan X, Li J, Sun Q (2015) A robust, anti-acid, and high-temperature–humidity-­ resistant superhydrophobic surface of wood based on a modified TiO2 film by fluoroalkyl silane. Surf Coat Technol 262:33–39 Garvanska R, Velev P, Dragnevska M, Lekova Sv, Parvanov Sv (2012) Modified nanocomposite wood fibrous materials with electromagnetic wave protection. In: 14th international symposium Materials, Methods & Technologies (MMT), 11–15 June 2012, Sunny Beach, Bulgaria, Proceeding, pp 41–50 Ghahri S, Pizzi A (2018) Improving soy-based adhesives for wood particleboard by tannins addition. Wood Sci Technol 52:261–279 Ghahri S, Mohebby B, Pizzi A, Mirshokraie A, Mansouri HR (2018) Improving water resistance of soy-based adhesives by vegetable tannins. J Polym Environ 26:1881–1890

Nanomaterials to Improve Properties in Wood-Based Composite Panels

151

Gul W, Shah SRA, Khan A, Pruncu CI (2021) Characterization of zinc oxide-urea formaldehyde Nano resin and its impact on the physical performance of medium-density fiberboard. Polymers 13:371 Gupta A, Kumar A, Sharma KV, Gupta R (2018) Application of high conductive nanoparticles to enhance the thermal and mechanical properties of wood composite. Mater Today Proc 5(1):3143–3149. [120] Hosseinpourpia R, Adamopoulos S, Mai C, Taghiyari HR (2019) Properties of medium-density fiberboards bonded with dextrin-based wood adhesives. Wood Res 64:185–194 Hu J, Shen Y, Pang S, Gao Y, Xiao G, Li S, Xu Y (2013) Application of hinokitiol potassium salt for wood preservative. J Environ Sci 25:32–35 Igaz R, Krišťák L, Ružiak I, Réh R, Danihelová Z (2016) Heat transfer during pressing of 3D molded veneer plywood composite material. Key Eng Mater 688:131–137 Ismita N, Lokesh C (2017) Effects of different nanoclay loadings on the physical and mechanical properties of Melia composite particle board. Bois Et For Des Trop 334:7–12 Jasmani L, Rusli R, Khadiran T, Jalil R, Adnan S (2020) Application of nanotechnology in wood-­ based products industry: a review. Nanoscale Res Lett 15:207 Kristak L, Antov P, Bekhta P, Lubis MAR, Iswanto AH, Reh R, Sedliacik J, Savov V, Taghiayri H, Papadopoulos AN, Pizzi A, Hejna A (2022) Recent progress in ultra-low formaldehyde emitting adhesive systems and formaldehyde scavengers in wood-based panels: a review. Wood Mater Sci Eng. https://doi.org/10.1080/17480272.2022.2056080 Li X, Gao Q, Xia C, Li J, Zhou X (2019) Urea formaldehyde resin resultant plywood with rapid formaldehyde release modified by tunnel-structured sepiolite. Polymers 11:1286 Li W, Chen M, Li Y, Sun J, Liu Y, Guo H (2020) Improving mildew resistance of soy meal by nano­Ag/TiO2, zinc pyrithione and 4-cumylphenol. Polymers 12:169 Lin L, Yang Y, Via BK, Liu Y, Guo H, Zhang F (2008) Modification and characterization of nano-­ Ag/TiO2 antimould agent for wood materials. Forest Prod J 68:70–77 Lin L, Cao G, Zhang J, Cui Q, Liu Y (2020) Enhanced anti-mold property and mechanism description of Ag/TiO2 wood-based nanocomposites formation by ultrasound – and vacuum-­ impregnation. Nano 10(4):682 Liu Yu, Zhu X, Yuan D, Wang W, Gao L (2020) Preparation and characterization of TiO2 based on wood templates. Sci Rep. [online]. Available at: https://www.nature.com/articles/ s41598-­020-­69440-­x. Last accessed 17 Apr 2022 Lu P, Yun H, Zhang W, Tu D, Hu C, Cherdchim B (2019) A facile method of superhydrophobic coating on rubberwood to improve its anti-mildew performance. Bioresources 14(3):7111–7121 Lubis MAR, Handika SO, Sari RK, Iswanto AH, Antov P, Kristak L, Seng-Hua L, Pizzi A (2022) Modification of ramie fiber via impregnation with low viscosity bio-polyurethane resins derived from lignin. Polymers 14(11):2165 Mantanis GI, Papadopoulos AN (2010a) The sorption of water vapour of wood treated with a nanotechnology compound. Wood Sci Technol 44:515–522 Mantanis GI, Papadopoulos AN (2010b) Reducing the thickness swelling of wood based panels by applying a nanotechnology compound. Eur J Wood Wood Prod, Springer, Verlag 68(2):237–239 Mantanis GI, Terzi E, Kartal SN, Papadopoulos AN (2014) Evaluation of mold, decay and termite resistance of pine wood treated with zinc and copper based nanocompounds. Int Biodeterior Biodegrad 90:140–144 Miyafuji H, Saka S (1997) Fire-resisting properties in several TiO2 wood-inorganic composites and their topochemistry. Wood Sci Technol 31:449–455 Nenkova S, Garvanska R, Velev P, Parvanov Sv, Dragnevska M, Kulevski M, Ilieva C, Behrendt G, Herzog M (2010) Method for production of electrically conductive wood-polymer composite materials for electromagnetic wave protection – Patent, reg. № 110663 / 26.05.2010 Nenkova S, Velev P, Dragnevska M, Nikolova D, Dimitrov K (2011) Lignocellulose nanocomposite containing copper sulfide. Bioresources 6(3):2356–2365

152

V. Savov

Nenkova S, Dragnevska M, Lekova Sv, Parvanov Sv, Radikolova T (2012) Nanocomposite wood fibrous materials for electromagnetic wave protection. In: 14th international symposium Materials, Methods & Technologies (MMT), Sunny Beach, Bulgaria, 11–15 June Ninikas K, Mitani A, Koutsianitis D, Ntalos G, Taghiyari HR, Papadopoulos AN (2021) Thermal and mechanical properties of green insulation composites made from cannabis and bark residues. J Compos Sci 5:132 Nosal E, Reinprecht L (2019) Anti-bacterial and anti-mold efficiency of silver nanoparticles present in melamine-laminated particleboard surfaces. Bioresources 14(2):3914–3924 Okyay TO, Bala RK, Nguyen HN, Atalay R, Bayam Y, Rodrigues DF (2015) Antibacterial properties and mechanisms of toxicity of sonochemically grown ZnO nanorods. RSC Adv 5:2568–2575 Olivato JB, Marini J, Yamashita F (2017) Sepiolite as a promising nanoclay for nano-­biocomposites based on starch and biodegradable polyester. Mater Sci Eng C 70:296–302 Palanti S, Feci E, Predieri G, Francesca V (2012) Copper complexes grafted to amino-­ functionalized silica gel as wood preservatives against fungal decay: mini-blocks and standard test. Bioresources 7:5611–5621 Papadopoulos AN (2010) Chemical modification of solid wood and wood raw materials for composites production with linear chain carboxylic acid anhydrides: a brief review. Bioresources 5(1):499–506 Papadopoulos AN, Taghiyari HR (2019) Innovative wood surface treatments based on nanotechnology. Coatings 9:866 Papadopoulos AN, Bikiaris DN, Mitropoulos AC, Kyzas GZ (2019) Nanomaterials and chemical modification technologies for enhanced wood properties: a review. Nano 9:607 Petya P, Antonio F, Margarida MF, Ernest M, Ilana P, Aharon G, Tzanko T (2014) Sonochemical coating of textiles with hybrid ZnO/chitosan antimicrobial nanoparticles. ACS Appl Mater Interfaces 6:1164–1172 Pizzi A (2019) Tannins: prospectives and actual industrial applications. Biomol Ther 2019(9):344 Pizzi A, Papadopulus A (2020) Wood composites and their polymer binders. Polymers 2020(12):1115 Reinprecht L, Iždinsky J, Vidholdova Z (2018) Biological resistance and application properties of particleboards containing nano-zinc oxide. Adv Mater Sci Eng 2018:1–9 Ružiak I, Igaz R, Krišťák L, Réh R, Mitterpach J, Očkajová A, Kučerka M (2017) Influence of urea-formaldehyde adhesive modification with beech bark on chosen properties of plywood. Bioresources 12(2):3250–3264 Salari A, Tabarsa T, Khazaeian A, Saraeian A (2013) Improving some of applied properties of oriented strand board (OSB) made from underutilized low quality Paulownia (Paulownia fortunei) wood employing nano-SiO2. Ind Crop Prod 42:1–9 Shi J, Avramidis S (2021) Nanopore-level wood-water interactions—a molecular simulation study. Forests 12(3):356 Silva LCL, Lima FO, Chahud E, Christoforo AL, Lahr FAR, Favarim HR et al (2019) Heat transfer and physical-mechanical properties analysis of particleboard produced with ZnO nanoparticles addition. Bioresources 14(4):9904–9915 Slabohm M, Mai C, Militz H (2022) Bonding acetylated veneer for engineered wood products—a review. Materials 10:3665 Sun Q, Yu H, Liu Y, Li J, Cui Y, Lu Y (2010) Prolonging the combustion duration of wood by TiO2 coating synthesized using cosolvent-controlled hydrothermal method. J Mater Sci 45:6661–6667 Taghiyari HR (2014) Nanotechnology in wood and wood-composite materials. J Nanomater Mol Nanotechnol 3(1): 1–2 Taghiyari HR, Schmidt O (2014) Nanotechnology in wood-based composite panels. Int J Bio-­ Inorg Hybr Nanomater 3(2):65–73

Nanomaterials to Improve Properties in Wood-Based Composite Panels

153

Taghiyari HR, Mobini K, Sarvari Samadi Y, Doosti Z, Karimi F, Asghari M, Jahangiri A, Nouri P (2013a) Effects of nano-wollastonite on thermal conductivity coefficient of medium-density fiberboard. J Mol Nanotechnol 2(1):1–5 Taghiyari HR, Moradiyan A, Farazi A (2013b) Effect of nanosilver on the rate of heat transfer to the core of the medium density fiberboard mat. Int J Bio-Inorg Hybrid Nanomater 2:303–308 Taghiyari HR, Ghorbanali M, Tahir PMD (2014) Effects of the improvement in thermal conductivity coefficient by nano-wollastonite on physical and mechanical properties in medium-density fiberboard (MDF). Bioresources 9:4138–4149 Taghiyari HR, Karimi A, Tahir PMD, Choo ACY (2015) Effects of nanotechnology on fluid flow. In: Hakeem KR, Jawaid M, Alothman OY (eds) Agricultural and wood-based composites materials. In: Agricultural biomass based potential materials. Springer, Cham. isbn:978-3-319-13846-6 Taghiyari HR, Norton J, Tajvidi M (2017a) Effects of nanomaterials on different properties of wood-composite materials. In: Bio-based wood adhesives: preparation, characterization, and testing. CRC Press/Taylor & Francis Group, Boca Raton, pp 310–339 Taghiyari HR, Hassani V, Maleki S, Eckelman CA (2017b) Effects of nano-wollastonite on screw withdrawal capacity of oriented strand lumber. J Nanomater Mol Nanotechnol 6:4 Taghiyari HR, Soltani A, Esmailpour A, Hassani V, Gholipour G, Papadopoulos AN (2020a) Improving thermal conductivity coefficient in Oriented Strand Lumber (OSL) using Sepiolite. Nano 10:599 Taghiyari HR, Esmailpour A, Adamopoulos S, Zereshki K, Hosseinpourpia R (2020b) Shear strength of heat-treated solid wood bonded with polyvinyl-acetate reinforced by nanowollastonite. Wood Res 65(2):183–194 Taghiyari HR, Militz H, Antov P, Papadopoulos AN (2021) Effects of wollastonite on fire properties of particleboard made from wood and chicken feather fibers. Coatings 11(5):518 Taghiyari HR, Majidi R, Mohseni Armaki SM, Haghighatparast M (2022) Graphene as reinforcing filler in polyvinyl acetate resin. Int J Adhes Adhes 113. https://doi.org/10.1016/j. ijadhadh.2021.103075 Vahabi H, Brosse N, Abd Latif NH, Fatriasari W, Solihat NN, Hashim R, Hussin MH, Laoutid F, Saeb MR (2022) Nanolignin in materials, science and technology – does flame retardancy matter? In: Biopolymeric nanomaterials. Elsevier, Amsterdam, pp 515–557 Valyova M, Ivanova Y, Koynov D (2017) Investigation of free formaldehyde quantity in production of plywood with modified urea-formaldehyde resin. Int J Wood Des Technol 6:72–76 Wang X, Yu R, Wang K, Yang G, Yu H (2015) Facile template-induced synthesis of Ag-modified TiO2 hollow octahedra with high photocatalytic activity. Chin J Catal 36:1211–2218 Wu Z, Huang D, Wei W, Wang W, Wang X, Wei Q, Niu M, Lin M, Rao J, Xie Y (2019) Mesoporous aluminosilicate improves mildew resistance of bamboo scrimber with CuBP anti-mildew agents. J Clean Prod 209:273–282 Xie G, Zhou Y, Cao Y, Li L (2018) Anti-mildew properties of copper cured heat-treated wood. Bioresources 13:5643–5655 Zhang X, Su H, Zhao Y, Tan T (2008) Antimicrobial activities of hydrophilic polyurethane/titanium dioxide complex film under visible light irradiation. J Photochem Photobiol A 199:123–129 Zhang X, Xiao F, Feng Q, Zheng J, Chen C, Chen H, Yang W (2020) Preparation of SiO2 nanoparticles with adjustable size for fabrication of SiO2/PMHS ORMOSIL superhydrophobic surface on cellulose-based substrates. Prog Org Coat 138:105384

Nanomaterials to Improve the Strength of Wooden Joints Roger Moya

and Carolina Tenorio

Contents 1  I ntroduction 2  Adhesives and Nanomaterials Used in Wood Joints 3  Adhesion Theory in Wood Joint and Its Implication in Adhesives Improve with Nanomaterials 4  Evaluation of Glue Line with the Adhesive Nanomodified Present in the Wood Joint 5  Evaluation for Glue Line with the Nanomodified Adhesive Present in the Wood Joint 6  Conclusions and Outlook References

 155  161  163  167  168  172  173

1 Introduction The wood joint is a fundamental and the most crucial part of woodworking, whose purpose is to maintain two pieces of wood together (Fleming 2020), or sometimes wood with other materials, such as plastic, metal and glass, known to create wood composites (Conrad et al. 2014; Wang et al. 2020). The purpose of wood joints is to maintain the mated and mechanically to interlock the manufacture of a more complex piece (Conrad et al. 2014) of higher strength (Baldan 2012) and design (Noll 2002) or to manufacture more attractive elements (Fleming 2020). This bonding can be done with a fastener (nail, screw or other material) and binding or adhesives (Fleming 2020). In the case of adhesive, the two wood pieces (two subtracts) are maintained together with the glue, forming a glued line (Wang et al. 2020), which is complex and is detailed later part of the present manuscript. R. Moya (*) · C. Tenorio Escuela de Ingeniería Forestal, Instituto Tecnológico de Costa Rica, Cartago, Costa Rica e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 H. R. Taghiyari et al. (eds.), Emerging Nanomaterials, https://doi.org/10.1007/978-3-031-17378-3_6

155

156

R. Moya and C. Tenorio

Fig. 1  Basic orientation of boards in wood joint: (a) parallel orientation, (b) I-orientation, (c) crossed orientation, (d) L-orientation, (e) T-orientation and (f) angled orientation

As the wood joint is fabricated with two different pieces of wood, there can be different configurations concerning the position (angle) formed between the two pieces of wood, specifically (Noll 2002): parallel orientation (Fig. 1a), I-orientation (Fig.  1b), crossed orientation (Fig.  1c), L-orientation (Fig.  1d), T-orientation (Fig. 1e) and angled orientation (Fig. 1f). These can be used in the production of furniture or large structural elements (Bedon and Fragiacomo 2019). Although these configurations are described, different geometries can be found in each type of configuration (Frihart and Hunt 2010). Though different materials are used to join the wood pieces having different orientations of boards in the wood joint, this chapter is focused only on the use of adhesives (adhesively bonded joints), since adhesives are one of the main and highly preferred nanomaterials for wood (Jasmani et al. 2020), apart from its application on surface enhancement (Papadopoulos and Kyzas 2019; Papadopoulos and Taghiyari 2019), as a preservative (Teng et al. 2018). Likewise, the reinforcement of structural elements also possesses a wide variety of applications in the wood joint as an important nanomaterial application. However, it is not considered in the present study as the effects of these are extensively summarized and reviewed by Bertolini-Cestari and Marzi (2021), Marzi (2015a, b), Yang et  al. (2020). Zhang et al. (2019) and Oke et al. (2017). Although applications of nanomaterials have emerged several years ago, during ancient times, human beings unknowing used nanomaterials for different purposes (Baig et al. 2021) while the earliest research was reported about nanoindentation by Moon et al. (2006). The use of nanocomposites (adhesives with different materials) emerged at the beginning of the present century (Marzi 2015a). Nanomaterials were earlier used only for reinforcement of wood joints as an adhesive but after 2006 it has also been used in other wood composites such as plywood, medium-density fibre (MDF), fibreboards or oriented strand board (OSB) (Ahmad et  al. (2006). These authors studied the influence of nanofillers on the thermal and mechanical behaviour of DGBA-based adhesives for timber connections. It is important to note that the application of nanomaterials in wood composites such as fibreboards,

Nanomaterials to Improve the Strength of Wooden Joints

157

Table 1  Different analytical and chemical tests were tested in adhesive modified with nanoparticles or nanofillers and mechanical and miscellaneous tests were applied in the wood joint (wood-adhesive-wood)

Reference Ahmad et al. (2006) Ahmad et al. (2010a) Ahmad et al. (2010b)

Analytical and Adhesive test and nanomaterial chemical testing used EP + nanosilica TEM, DMTA EP + nanosilica and Viscosity, nanorubber contact angle EP + nanosilica

Ahmad et al. (2010c)

EP + nanosilica and nanorubber

Ahmad et al. (2011a) Ahmad et al. (2011b) Ahmad et al. (2011c)

EP + nanosilica and nanoceramic EP + nanosilica

Ahmad et al. (2012a) Ahmad et al. (2012b) Amran and Ali (2015)

EP + nanosilica and nanorubber EP + nanorubber

Ayrilmis et al. (2016) Azamian Jazi et al. (2020) Bardak et al. (2016)

PVAc + cellulose nanofibrils and nanoclay PVAc + nanosilica PVAc + nanosilicon dioxide and titanium dioxide

Bardak et al. (2017)

PVAc + nanosilicon dioxide and titanium dioxide

EP + nanosilica and nanoceramic

pMDI and nanoclay fillers

TEM

DMTA, DSC Viscosity, contact angle TEM DMTA, TEM FTIR, contact angle TGA

Mechanical testing and miscellaneous test SB with EN 178 SS with ASTM D 905 and pull out test TT with ASTM D638, SS with ASTM D 198 and WA TT with ASTM D638, Charpy impact test BS ISO 179 and fracture toughness and strain energy test with ASTM D5045 WA and diffusion

Penetration test SEM SEM

SEM

SEM SS with ASTM D905

SEM

SB and creep test with EN178) Creep test with EN178 SS D906

SEM

TT with TS 392 and SEM ISO 12579 FTIR, TST and TT, China FESEM TGA, DCS Industrial Standard TGA, SS with ASTM XRD, TEM D905 and ASTM 7247 Bending test, tenon joints and tension test in the orientation of boards in wood joint (continued)

158

R. Moya and C. Tenorio

Table 1 (continued)

Reference Bardak et al. (2018)

Analytical and Adhesive test and nanomaterial chemical testing used XRD, viscosity

Mechanical testing and miscellaneous test SB with EN 302, The Turkish Standards Institute used was TS 2474 Three-point bending test

Penetration test

Bertolini-­ Cestari et al. (2013) Cazotti et al. (2021)

EP + multiwall carbon nanotubes and nanoclay

FEM

SEM

PVAc + nanoclay

Chaabouni and Boufi (2017) Chen et al. (2019)

PVAc + cellulose nanofillers

SEM DLS, XRD, TSS-L-J with EN 205 and DMA, TGA, TEM classification by EN 204 DMA, TSS-L-J with EN viscosity 205

SEM, SS with ASTM D5868, cold water CFSLM soaking test and boiled water soaking test Product Standard PS 1–95. Cheng et al. Cottonseed protein-based wood FTIR, TGA TST of the adhesive water exposition (2019) adhesives + cellulose with ASTM D1151 nanofibers Chen et al. Cottonseed protein-based wood DSC L-J with ASTM (2020) adhesives D5868 Damásio et al. UF + cellulose nanocrystals TEM, AFM TST with ASTM D (2017) 2339 SEM L-J with ASTM XRD, Deka and Hyperbranched polyurethane D3165 and TST TEM, Karac (2011) with organically modified with ASTM D906 FTIR, nanoclay DSC, TGA Fernandes UF + nanoclay TST with ASTM D et al. (2017) 2339 TST with ASTM Gadhave et al. PVAc + microcrystalline FTIR, D906 (2021) cellulose DMA, DSC, water contact angle SS with ASTM Góral et al. PVAc + nanoceramic fillers TG-DSC, D905, pyrolysis (2021) viscosity, combustion flow pH, calorimetry, horizontal burning test pMDI adhesive + lignin-­ containing cellulose nanofibril

FTIR, DSC,

(continued)

Nanomaterials to Improve the Strength of Wooden Joints

159

Table 1 (continued)

Reference Ismita et al. (2019a, b) Jawad et al. (2020) Jiang et al. (2018) Kaboorani and Riedl (2011) Kaboorani et al. (2012)

Analytical and Adhesive test and nanomaterial chemical testing used UF + nanoclay PVAc + nanotitanium dioxide PVAc + cellulose nanofibrils PVAc + nanoclay

PVAc + nanocrystal cellulose

Mechanical testing and miscellaneous test SB on finger joint Kumar et al., 2017 Viscosity TST with ASTM D2339 TSS-L-J with EN 205 TGA, SS with ASTM XRD, TEM 7247

AFM, SS with ASTM TGA, TEM D905 and ASTM D7247 Kaboorani PVAc + nanoclay XRD, SS with ASTM et al. (2013) AFM, TEM D905 and ASTM 7247 FT-IR, SS with EN 314–1 Kawalerczyk PF + nanocellulose and SB with EN et al. (2020a, UF + nanocellulose 310 b, 2021) Kwon et al. UF + micro fibrillated cellulose TSS-L-J with EN (2015) 205 Impact toughness Li et al. PF + nanocupper TEM, ISO 13061-10, (2021) AFM, Compressive ESEM, strength ISO 3129 FTIR Liu et al. PF + cellulose nanofiber AFM Hardness and (2014, 2018) PF + nanocrystalline cellulose elasticity module with NI Lopes et al. UF + nanolignin kraft TEM, SEM SS dry with ASTM (2020) D2339 and SS wet with NBR ISO 12466-1 López-Suevos PVAc + cellulose nanofibrils DMA, TSS-L-J with EN et al. (2010) 205 Marini et al. PVAc or MUF + cellulose UVF TSS-L-J with EN (2020) nanocrystals 205 SS with ASTM D AFM, Moya et al. PVAc or UF + nanoclay 905 TEM, (2015a, b) PVAc or UF + multiwall TGA, carbon nanotubes colour Nautiyal et al. UF + nanoclay SB (2020) TGA, FTIR TST with ASTM Oh et al. Aein-and gluten-based D2339 and SB with (2019) adhesives + cellulose ASTM D1037 nanofibers

Penetration test

NI

SEM

SEM

NI, SEM

SEM

SEM SEM SEM

SEM

(continued)

160

R. Moya and C. Tenorio

Table 1 (continued)

Reference Olad et al. (2021) Ozcifci et al. (2018) Peruzzo et al. (2014) Podlena et al. (2021) Raabe et al. (2016) Rigg-Aguilar et al. (2020) Tankut et al. (2016) Veigel et al. (2011) Vineeth et al. (2020)

Analytical and Adhesive test and nanomaterial chemical testing used PVAc + nanosilica XDR, FTIR, TGA PF or MUF + nanosilicon dioxide and titanium dioxide PVAc + nanoclay TEM, WAXD, TGA Soy protein-based adhesives + cellulose nanofibrils RF + nanosilicon dioxide PVAc or UF + nanofibrillated cellulose PVAc or MUF + nanosilicon dioxide and titanium dioxide UF + cellulose nanofibrils Cellulose nanofibrils + microcrystalline cellulose

Wang et al. (2011)

Starch-based wood adhesive + nanosilicon dioxide

Wang et al. (2017)

PF + nanoclay

Wibowo et al. UF + cellulose nanofibrils (2021) Yang et al. PRF + nanosized lignin and (2019) microlignin Younesi-­ Kordkheili (2017)

Glyoxalated lignin- urea-­ glyoxal adhesive + nanoclay

Zhang et al. (2011)

UF + nanocrystalline cellulose

Mechanical testing and miscellaneous test L-J with ASTM D1002 TSS-L-J with EN 205 TSS-L-J with EN205 and EN 1425 SS with ASTM D905

TST with ASTM D 2339 AFM, SS with ASTM TGA, FTIR D905 L-J with DIN EN 302–1 XRD FTIR, DMA, DSC, contact angle FTIR, TGA

FTIR, TEM, TGA, XRD FTIR, XRD

Penetration test SEM SEM

SEM

SEM, NI

Pencil hardness test with ASTM D3363, and TST with ASTM D906 SEM TST with the industry standard of HG/T 2727 from China SB and TST with China National Standard TST by Korean Standard TSS-L-J with EN 205

DSC, TGA, TMA, XPS, FTIR XRD SS with ASTM D906, SB with EN-310 and WA with ASTM D1037 XRD, TGA SS with Chinese National Standard GB/T 17657

(continued)

161

Nanomaterials to Improve the Strength of Wooden Joints Table 1 (continued)

Reference Zhang et al. (2015) Zidanes et al. (2021)

Analytical and Adhesive test and nanomaterial chemical testing used UF + nanofibrillated cellulose

Tannin-based adhesives + cellulose nanofibrils

FTIR, raman, TGA, viscosity

Mechanical testing and miscellaneous Penetration test test NI, SEM SS without information about standards utilized. TST with ASTM D2339 and SS with EN 314–1

plywood or nanocomposites, is very wide due to the high adhesive consumption in these products.

2 Adhesives and Nanomaterials Used in Wood Joints Before focusing on the effects of nanomaterials on wood adhesion theories, it is important to look at the types of nanomaterials that are used in the wood joint (Table 1). There are several types of adhesives: a predominance polyvinyl acetate (PVAc), urea-formaldehyde (UF) and epoxy adhesives (EP), followed by resorcinol formaldehyde (RF), urea melamine-formaldehyde (MUF), polymeric diphenylmethane diisocyanate (pMDP) and phenol-formaldehyde (PF). More recently, natural adhesives such as cottonseed protein-based (Cheng et al. 2019; Chen et al. 2020), soy protein (Podlena et al. 2021), zein-and gluten-based (Oh et al. 2019), tannin-­ based adhesives or lignin derivatives (Yang et al. 2019; Younesi-Kordkheili 2017) are also modified with nanomaterials (Table 1). Although there is a wide variety of adhesives tested in the wood joint from a significant number of adhesives available (Stoeckel et al. 2013), it is observed that most of them are oriented to non-structural adhesives, such as PVAc and UF (Fig. 2). Thus, the potential for these adhesives is oriented in non-structural elements, such as in the fabrication of furniture and light-frame structures/articles, in particleboard, medium-density board (MDF) or plywood fabrication. Other less used adhesives are EP, pMDP, RF, PF and MUF (Fig. 2), which are structural adhesives but there are only a few studies that are found on them, for example, Ahmad et  al. (2006, 2010a, b, c, 2011a, b, c, 2012a, b) and Bertolini-­ Cestari et al. (2013) with EP, Amran and Ali (2015) and Chen et al. (2019) with pMDI, Kawalerczyk et  al. (2020a, b), Liu et  al. (2014, 2018) and Ozcifci et  al. (2018) with PF and Tankut et al. (2016) with MUF.

162

R. Moya and C. Tenorio

Fig. 2  Distribution in the percentage of different adhesives modified with nanomaterials (a) and different tests utilized (b) in the wood joint

Fig. 3  Different parts of wood joint: glue line and subtracts or wood pieces

Regarding nanomaterials, it was observed that nanocellulose derivatives (nanocrystals, nanofillers or others) are the most used when adhesives are nanomodified for wood joints (Table 1). Recently, lignin derivatives are being tested while nanoclay, nanosilicon dioxide (nano-SiO2), nanotitanium dioxide (nano-TiO2), nanowollastonite, graphene and nanosilica are of minor importance to modifying adhesive in the wood joint (Azamian Jazi et  al. 2020; Raabe et  al. 2016; Jawad et  al. 2020; Ozcifci et al. 2018; Taghiyari et al., 2020, 2022).

163

Nanomaterials to Improve the Strength of Wooden Joints Table 2  Different testing methods for adhesive and wood joint evaluation Analytical and chemical testing Spectroscopy Gel permeation chromatography (GPC) Differential scanning calorimetry (DSC) Dynamic mechanical analysis (DMA) Torsional-braid analysis (TBA) Atomic force microscope (AFM) Fourier transform infrared spectroscopy (FT-IT) Thermal gravimetric analysis (TGA) Differential Thermal Analysis (DTA) Dynamic mechanical analysis (DMA) Dynamic mechanical thermal analyser Transmission electron microscope (TEM) Viscosity Contact angle pH Adhesive colour

Penetration test Microscopy (visible light, UV, IR) Nanoindentation (NI) Scanning electron microscope (SEM) Epifluorescence microscopy (EPI) High-resolution episcopic microscopy (HREM) X-ray computed tomography (XCT) Optical projection tomography (OPT) Magnetic resonance imaging (MRI) Nuclear magnetic resonance (NMR) X-ray photoelectron spectroscopy (XFS) Confocal laser scanning microscopy (CLSM)

Mechanical testing Shear Tension Spot adhesion Cleavage Peel Ageing Accelerated Ageing Delamination Lap-joint Tension Flexure Heat and moisture resistance Chemical, light, radiation, and organism exposition

3 Adhesion Theory in Wood Joint and Its Implication in Adhesives Improve with Nanomaterials Two parts can be distinguished in wood joint geometry (Fig.  3): the first corresponds to the bond line or glue line which would be the adhesive layer and the second part corresponds to the wood pieces or the substrate. As for the adhesive, there are two types of penetration into the wood: a region of wood where the adhesive penetrates, i.e. the empty spaces of the cell (lumens or cell spaces), and the second region of penetration where the adhesive penetrated in the cell wall (Ülker 2016). The first type of penetration is easily observed with the help of visual techniques (Modzel et  al. 2011), while the second type of penetration requires other types of techniques such as X-ray, AFM and nanoindentation (Table 2). Hunt et al. (2018) and a review of the literature indicate the different forces involved in the adhesion theories or mechanisms can be determined using nanoindentation techniques (Gardner et al. 2014; Schultz and Nardin 1994; Hunt et al. 2018) (Fig. 4). Glue line is an important part of adhesively bonded joints, and it is the one that allows giving strength to the joint; consequently, it plays a crucial role in designing safe and durable wooden structures (Clerc et al. 2019). Therefore, the adhesive must

164

R. Moya and C. Tenorio

Fig. 4  Visual penetration in cross section of wood joints bonded by pMDI adhesives using confocal laser scanning microscopy (CLSM). (a) illustrates the penetration of pMDI without nanomodification into the wood substrate. Here, here the penetration up to 8–9 partly filled vessels on one side of the bondline and adhesive filled a large portion of the fibre lumens which were close to the wood surface. (b) the adhesive modified lignin-containing cellulose nanofibril at 3% penetrated similarly to adhesive without modification. (c) shows that the adhesive modified lignin-containing cellulose nanofibril at 10% penetrated to a less degree due to its much higher viscosity (Chen et al. 2019)

Fig. 5  Common link established or presented in glue line of wood joint: (1) layer adhesive link, (2 and 3) boundary adhesive link, (4 and 5) link in adhesion mechanism, (6 and 7) link of interphase subtracts and adhesive and (8 and 9) unadulterated wood link

penetrate and distribute the stresses efficiently to achieve increased strength and stiffness of the joint (Frihart and Hunt 2010). Moreover, the incorporation of a nanocomposite in the adhesive must maintain the same principle in glued line and consequently in wood joints too. The effective transfer of strength and stiffness from one part to the other in the wood joint depends on the links established within the adhesive itself and at the wood-adhesive interface (Collett 1972; Frihart and Hunt 2010). There are nine mechanical links defined in glue line in two pieces in the wood joint (Fig. 5): layer adhesive link, boundary adhesive link, link in adhesion mechanism, link of interphase subtracts and adhesive and unadulterated wood link, which has a specific localization in the glue line (Marra 1992).

Nanomaterials to Improve the Strength of Wooden Joints

165

The theories of adhesion in the glue line of the wood joints must be fully understood, as various factors are involved and must be considered when using nanomaterials (Baldan 2012). For example, the anisotropy of the wood can influence the different parts of the wood joint geometry, in the wood joint with parallel and crossed orientation (Fig. 1a, c), the two pieces of wood are placed longitudinally, so the penetration can be in the radial or tangential direction. In the case of joint wood with I-orientation, the glue line occurs in the transverse direction of the two pieces of wood (Fig. 1b), while in other orientations the transverse direction of one piece of wood intervenes with the longitudinal direction of the other piece of wood (Fig. 1d–f). Accordingly, the adhesion can be different in each of the different configurations of the wood joints and the influence of nanomaterials, which will have different effects as the joints mainly affect the penetration of the adhesive into the wood (Sanghvi Malav et al. 2022). It is well accepted that seven different adhesion mechanisms interfere between the adhesive and the wood joint (Gardner et al. 2014), which must be fully understood when improving the behaviour of the joint wood with the use of a nanomaterial: 1. Mechanical interlocking theory represents the basic adhesion theory and is based on the fact that the wood surface presents irregularities, pores or cavities where adhesives penetrate and mechanically adhere; thus, the adhesive can flow into the lumen of the cells and provide high strength 2. Electronic or electrostatic theory: In this theory, the wood-adhesive interface is considered analogous to the plates of an electrical capacitor through which charge transfer occurs and the adhesion strength is attributed to electrostatic forces 3. Adsorption (thermodynamic) or wetting theory: Thermodynamic adhesion or wetting refers to the atomic and molecular interactions between adhesives and adherents 4. Diffusion theory is based on the concept that two materials are soluble or compatible with each other, and if placed in close contact, they dissolve into each other and form an interface that is a solution of both materials in between; therefore, it does not form a discontinuity of physical properties between the two materials 5. Chemical (covalent) bonding theory is based on a covalent bond being formed, where two atoms share a pair of electrons and are believed to improve the durability of the bond between the wood and an adhesive 6. Acid-base theory: An acid (electron-acceptor) is bonded to a base (electron-­ donor) by sharing the electron pair offered by the latter, which forms a coordinate bond 7. Theory of weak boundary layers: In this model, three weak boundary layers are present: air bubbles, impurities at the interface and reactions between components and the medium. It is pointed out that the interface is the place where the failure of a bonded assembly occurs when a weak boundary layer is present

166

R. Moya and C. Tenorio

As with the effects of nanomaterials on the different wood joint configurations, the effects of nanomodified products on the different adhesion theories or common links established or presented in the glue line of the wood joint (Fig. 1) are poorly known. Imperative reviews have been published on the interaction of nanomaterials in adhesives, the most important being cellulose derivatives (nanocrystals or nanofiller). Recently, lignin-derived nanoproducts in the different adhesives used in a wood joint or other wood compositions are also worked out (Trache et al. 2020). For example, Gardner and Tajvidi (2016) and Tajvidi et al. (2016) while studying the importance of hydrogen bonding in cellulose nanocomposites indicate that cellulose nanofillers establish enlaced hydrogen bonding and wood particles, thus suggesting the effect of these nanofillers on link 6 and 7 presented in the glue line. However, the effects of nanoparticles or nanofiller added wood adhesive on the links of interphase subtract and adhesive (links 6 and 7 of Fig. 1) or unadulterated wood link (links 8 and 9 of Fig.  1) are less known and are poorly understood. More recently, Trache et al. (2020) and Lengowski et al. (2019) refer again to the adhesion of nanocellulose with adhesive and the change in adhesive properties and strength but describe little about the interaction of nanocellulose with wood components or the different links interacting with the substrate. In contrast to the research conducted by Fritz and Olivera (2022) who detailed the mechanisms of adhesion and different links associated of nanocellulose adhesion with wood components. Very recently, significant research has also been developed on the application of lignin nanoderivatives on wood joint behaviour (Chen et al. 2019, 2020; Lopes et al. 2020; Yang et al. 2019). Karthäuser et al. (2021) specified that lignin derivatives are of interest for various applications in wood products and most of the research has been carried out on the application of lignin as an adhesive. However, according to the authors (Karthäuser et  al. 2021), this use should be evaluated more carefully because the material must enter and diffuse into the cell walls from the lumen through micropores, which after swelling have a maximum diameter of 2–4 nm in a water-saturated state, while the lignin molecules are too large to enter, so applications for nanoderivatives to wood modifications that improve dimensional stability, moisture resistance and biodegradation, etc., are recommended. Kamel (2007), for the first time, reviewed the effects of the use of nanomaterials in adhesives and their interactions with different types of materials or substrates, but again the interference in the different links 6–7 or 8–9 present in the glue line is little explored. Dorieh et al. (2022) studied the effects of nanomaterials, such as silver nanoparticles, silica (SiO2), titanium oxide (TiO2) or alumina oxide (Al2O3), on the strength, curing time and emissions of urea-formaldehyde resins without emphasizing the effects of these nanoparticles with wood components. Regarding the use of silver nanoparticles, Joo and Baldwin (2009) described different adhesion mechanisms of these particles on different types of substrates used in printed electronics applications; however, this examination was focused on the adhesion of NPS to organic materials like widely used polyimide Kapton HN and Kapton FPC dry films. Another important aspect to highlight is the importance of nanofillers in wood adhesives that are widely used (Sanghvi Malav et al. 2022) that have implications for the wood joint. In general, fillers in the wood adhesives can increase viscosity,

Nanomaterials to Improve the Strength of Wooden Joints

167

control the rheology, achieve higher thermal and dimensional stability, get better mechanical properties, etc. This improvement in properties is attributed to these fillers sealing the pores present on the wood surface, which leads to lower the unwanted adhesive flow, better bonding between the components and less resin penetration into the pores (Sanghvi Malav et al. 2022). In this review, reference is made to the diffusion penetration of the adhesive into the wood joint, which is important in the structural performance of the adhesive (Baldan 2012), but a little description is provided on the cross-link effects of the adhesives and the nanofillers.

4 Evaluation of Glue Line with the Adhesive Nanomodified Present in the Wood Joint The behaviour of the adhesive in wood joints must be tested to ensure that the wood pieces remain bonded for the long-term existence of the structure (Frihart and Hunt 2010), especially when the wood joints are enhanced with nanomaterials. Methods for testing wood joint strength must predict the strength under shear, tensile or other loads at a specific temperature and humidity conditions for a given time (Pizzo and Smedly 2015). Glue line in the wood joint testing is classified as short-term and is based on the chemical, mechanical and rheological laboratory testing of polymers in the adhesive and the glue line assembly of the two substrates. In contrast, medium-term tests of glue line products are carried out in pilot operations and field experiments, in which short-term laboratory tests are extrapolated (DeVries and Adams 2002). For this purpose, some wood joints are evaluated in long-term tests under real environmental exposures, but this information will take time and will be available after 10–30 years. Therefore, short-term tests are widely used to predict the long-term performance of the wood joint (Frihart and Hunt 2010).

Fig. 6  A creep long-term test setup can be utilized for materials adhesive nanomodified with nanoparticles

168

R. Moya and C. Tenorio

Long-term tests on wood joints are generally associated with creep (Holzer et al. 1989) but studies on nanomaterial-enhanced wood joints there are limited. In this connection, Ahmad et al. (2012a) conducted a creep test for epoxy-based adhesive reinforced with 2% in weight of nanoparticles of nanorubber [carboxyl-terminated butadiene and acrylonitrile (CTBN)] for bonding in timber connection. A three-­ point bend test by placing the specimens on a custom-made test rig placed in an environmental chamber was conducted in creep tests and Fig. 6 can be represented the way to creep determination. These authors indicated that based on the results of the creep test, the addition of nanoparticles allowed to show the adhesive improvement. Other tests that can be applied to improve the wood joint with nanomaterial accelerated ageing tests that are considered equivalent to the medium-term tests, for which ASTM D-1183, ASTM D-3434 and ASTM D-3632 standards can be used. However, information on wood joints fabricated with nanomaterials is neglected and limited information is available on this aspect. Chen et al. (2019) applied accelerated testing of the wood joint using plywood standards (Voluntary products Standard PS 1–95) in polymeric diphenylmethane diisocyanate (pMDI) adhesives that were modified with lignin-containing cellulose nanofibril and the obtained results showed that accelerated testing is a good indicator to define the behaviour of nanomodified adhesive.

5 Evaluation for Glue Line with the Nanomodified Adhesive Present in the Wood Joint There are different testing methods to evaluate the adhesives that are used in the wood joint and that can be applied when the wood joint is enhanced with nanomaterials. These methods are classified as analytical and chemical, penetration and mechanical testing (Table 3). There are several types of testing (Table 1); the former type (i.e. analytical and chemical) analyses the adhesives in the wood joint for evaluating the penetration of the adhesive into the substrate and each of them has its advantages or disadvantages (Shirmohammadi and Leggate 2021). Analytical and chemical testing is the most used techniques that are employed in the different studies that are involved with the wood joint improvement using nanomaterials (Table 1). Perhaps many of these can explain the effect of the modification or new link presented in the adhesive itself. Specifically, these links are the layer adhesive link (link 1 in Fig. 1), boundary adhesive link (links 2 and 3 in Fig. 1) and link in adhesion mechanism (links 4 and 5  in Fig.  1). Various studies show the effects of improvement of wood joints by using nanomaterials. These studies have mostly used a technique for evaluating the changes in the adhesive. However, these studies are variable for both types of adhesives as well as for the analytical and chemical tests (Table 2). As shown in Fig. 1, there are other bonds involved in the wood joint. The formation of chemical cross-linking bonds (van der Waals,

Nanomaterials to Improve the Strength of Wooden Joints

169

Table 3  Selected ASTM test methods can be used for the evaluation of wood joints using adhesives improved with nanomaterials Test Tension

Shear

Peel

ASTM assignation and description D-906 Standard test method for strength properties of adhesives in plywood type construction in shear by tension loading D-0897 Standard test method for tensile properties of adhesive bonds D-2094 Standard practice for preparation of bar and rod specimens for adhesion tests D-2339 Standard test method for strength properties of adhesives in two-plywood construction in shear by tension loading D-1002 Standard test method for apparent shear strength of single-lap-joint adhesively bonded metal specimens by tension loading (metal-to-metal) D-1344 Standard method of testing cross-lap specimens for tensile properties of adhesives (discontinued) D-2095 Standard test method for tensile strength of adhesives by employing bar and rod specimens D-3808 Standard test method for qualitative determination of adhesion of adhesives to substrates by spot adhesion D-4688 Standard test method for evaluating structural adhesives for finger jointing lumber C-0297 Standard test method for flatwise tensile strength of sandwich constructions D-905 Standard test method for strength properties of adhesive bonds in shear by compression loading D-3165 Standard test method for strength properties of adhesives in shear by tension loading of single-lap-joint laminated assemblies D-3528 Standard test method for strength properties of double lap shear adhesive joints by tension loading D- 3931 Standard test method for determining the strength of gap-filling adhesive bonds in shear by compression loading D- 3983 Standard test method for measuring strength and shear modulus of nonrigid adhesives by the thick-adherend tensile-lap specimen D- 4027 Standard test method for measuring shear properties of structural adhesives by the modified-rail test D-4501 Standard test method for shear strength of adhesive bonds between rigid substrates by the block-shear method D-4896 Standard guide for use of adhesive-bonded single lap-joint specimen test results E-229 Standard test method for shear strength and shear modulus of structural adhesives D-7247 Standard test method for evaluating the shear strength of adhesive bonds in laminated wood products at elevated temperatures D-1876 Standard test method for peel resistance of adhesives (t-peel test) D-3167 Standard test method for floating roller peel resistance of adhesives D-1781 Standard test method for climbing drum peel for adhesives D-0903 Standard test method for peel or stripping strength of adhesive bonds (continued)

hydrogen bond, etc.) is very complex and depends on many factors and are not only associated with the type of adhesive (Hunt et al. 2018), but also with factors related to the preparation of the substrates or the two different pieces of wood (Frihart and Hunt 2010).

R. Moya and C. Tenorio

170 Table 3 (continued) Test Other and miscellaneous

ASTM assignation and description D-0950 Standard test method for impact strength of adhesive bonds D-1151 Standard practice for the effect of moisture and temperature on the adhesive bond D-1183 Standard practices for resistance of adhesives to cyclic laboratory ageing conditions D-2559 Standard specification for adhesives for bonded structural wood products for use under exterior exposure conditions D-3434 Standard test method for the multiple-cycle accelerated ageing test (automatic boil test) for exterior wet use wood adhesives D-3632 Standard test method for accelerated ageing of adhesive joints by the oxygen-pressure method D-4502 Standard test method for heat and moisture resistance of wood-­ adhesive joints G-53 Standard practice for operating light-and water-exposure apparatus (fluorescent UV-condensation type) for exposure of non-metallic materials (discontinued) D-1828 Standard practice for atmospheric exposure of adhesive-bonded joints and structures D-1879 Standard practice for exposure of adhesive specimens to ionizing radiation D-3310 Standard test method for determining corrosivity of adhesive materials D-4680 Standard test method for creep and time to failure of adhesives in static shear by compression loading (wood-to-wood) D-2918 Standard test method for durability assessment of adhesive joints stressed in peel D-2919 Standard test method for determining the durability of adhesive joints stressed in shear by tension loading D-4300 Standard test methods for the ability of adhesive films to support or resist the growth of fungi D-4783 Standard test methods for resistance of adhesive preparations in the container to attack by bacteria, yeast, and fungi D-1383 Standard test method for susceptibility of dry adhesive films to attack by laboratory rats D-896 Standard practice for resistance of adhesive bonds to chemical reagents

Mechanical testing is diverse but the most widely used values are the American Society for Testing and Material (ASTM) standards (Pocius 2012). There are other standards such as the International Standards Organization (ISO), the European Committee of Standardization-EN standard, or standards from development for different countries that are also used in the wood joint. The case of ASTM contemplates a series of standards (Table 3) that can be applied to wood joints (DeVries and Adams 2002; Pocius 2012) and in wood joints fabricated with adhesives improved with nanomaterials. The tests applied to different wood joints using nanomaterials in adhesives are detailed in Table 1. ASTM standards are the most applied, among which ASTM D-905, ASTM D-906 and ASTM D-2339 stand out (Fig.  2b), followed by EN 205 from EN standards, while less frequently used are ASTM D638,

Nanomaterials to Improve the Strength of Wooden Joints

171

Fig. 7  Non-typical mechanical testing performance by Bardak et al. (2017) in mortise and tenon wood joint with adhesive nanomodified

ASTM D7247, ASTM D5868, ASTM D1151, ASTM D638, EN 302, EN 314 (Fig.  2b). Other standards from different countries are also used to evaluate the wood joint that is fabricated by using the adhesive modified with nanomaterials (Table 3). Other information that emerges from the investigation performed on the wood joints related to tensile and shear stresses test comes from the nanomodified adhesives (Table 2), specifically shear test (SS), tensile shear test (TST), lap joint tensile shear strength (TSS-L-J), lap joint shear strength (L-J) and tension test (TT). Other mechanical tests (static bending, impact strength or compressive strength) also can be used on nanomodified wood joint adhesives. For example, studies conducted on the static bending test with nanomodified adhesives by different researchers (Bardak et al. 2017, 2018; Bertolini-Cestari et al. 2013; Kawalerczyk et al. 2020a, b; Wang et al. 2017; Younesi-Kordkheili 2017) showed the increase in the mechanical property with modifications of the adhesives with different nanomaterials. Li et  al. (2021) conducted impact and compressive strength tests to evaluate nanocomposite-­ modified FPs and reported that these mechanical properties increase by 21% by adding 1% nanocupper. Non-typical tests of different wood joints were tested by Bardak et al. (2017), who prepared mortise-and-tenon wood joints (Fig. 7) with PVAc adhesive and silicon dioxide and titanium dioxide nanofillers using beech and oak wood. They showed that the addition of nanoparticles (1% or 2%  w/w) improved the performance of both joints, but the addition of 4% nanoparticles decreased the strength. The authors concluded that nanoparticles in the adhesive provide a means to achieve a strong bond for furniture applications.

172

R. Moya and C. Tenorio

6 Conclusions and Outlook The wood joint presents a variety of configurations involving different orientations of the wood pieces, which can have different behaviour when the adhesive is modified with nanomaterials. However, the most used tests are performed in parallel orientation (Fig. 1a), leaving other important orientations and configurations of the wood joint. Despite this problem, some special tests for wood joints fabricated with nanomaterials had begun to be implemented. For example, Bardak et  al. (2017) reported a positive effect on resistance in mortise and teno wood joint PVAc adhesive modified with nanosilicon dioxide and nanotitanium dioxide nanofillers. The theories of adhesion and a common link established in glue line of wood joints although they are well known in different adhesives (Gardner et al. 2014), the effects on modified adhesives are limited. Considerable information is available on nanomaterial and resin type, specifically on layer adhesive link and boundary adhesive link; however, little has been explored about the adhesion mechanism link of interphase subtract and adhesive, and unadulterated wood link, though these links are important for glue line performance. Adhesives have a wide variety of uses; among them, they have important applications in structural elements since they are often associated with the wood joint. Although different nanomodified adhesives have emerged, many of them are oriented to non-structural adhesives (PVAc and UF adhesives). Therefore, it is an urgent need to enhance research on the use of nanomaterials in structural adhesives along with the use of mechanical testing oriented to structural uses. Adhesives modified with nanomaterials from cellulose, nanosilicon dioxide (nano-SiO2), nano-titanium dioxide (nano-TiO2) and nanosilica have shown improved strength properties in the wood joint; however, these are based on limited tests measuring shear and tensile strength, yet with uncertainty in strength modification for long-term duration tests or other miscellaneous testing applied to adhesives are warranted further. Many potential standards can be used for the evaluation of wood joints using adhesives improved with nanomaterials in the wood joint (Table  3). However, although many adhesives, nanomaterials or mechanical testing had been applied for wood joint evaluation, limited standards have been used for wood joint assessment, and they are mainly oriented to measure shear and tension resistance. Therefore, it is necessary to expand the amount of testing for the different adhesives modified with nanomaterials especially those oriented to evaluate the long-term effects, specific situations such as water resistance, temperature and microorganisms, among others. Acknowledgements  The authors wish to thank the Vicerrectoria de Investigación y Extensión at the Instituto Tecnológico de Costa Rica (ITCR).

Nanomaterials to Improve the Strength of Wooden Joints

173

References Ahmad Z, Ansell MP, Smedley D (2006) Influence of nanofillers on the thermal and mechanical behavior of DGEBA-based adhesives for bonded-in timber connections. Mech Comp Mat 42(5):419–430 Ahmad Z, Ansell MP, Smedley D (2010a) Epoxy adhesives modified with nano  – and micro-­ particles for in-situ timber bonding: effect of microstructure on bond integrity. Int J Mech Mater Eng 5:59–67 Ahmad Z, Ansell MP, Smedley D (2010b) Epoxy adhesives modified with nano-and microparticles for in situ timber bonding: effect of environment on mechanical properties and moisture uptake. J Eng Mater Technol 132(3):031916 Ahmad Z, Ansell MP, Smedley D (2010c) Thermal properties of epoxy-based adhesive reinforced with nano and micro-particles for in-situ timber bonding. Int J Eng Technol 10(2):32–38 Ahmad Z, Ansell MP, Smedley D (2011a) Moisture absorption characteristics of epoxy-based adhesive reinforced with CTBN and ceramic particles for bonded-in timber connection: fickian or non-Fickian behaviour. IOP Conf Series: Mat Sci Eng 17(1):012011 Ahmad Z, Ansell MP, Smedley D (2011b) Epoxy adhesives modified with nano-and microparticles for in situ timber bonding: fracture toughness characteristics. J Eng Mater Technol 133(3):031016 Ahmad Z, Ansell MP, Smedley D (2011c) Bonding strength properties of adhesively-timber joint with thixotropic and room temperature cured epoxy-based adhesive reinforced with nano-and micro-particles. IOP Conf Series: Mat Sci Eng 17(1):012007 Ahmad Z, Ansell M, Smedley D, Tahir PM (2012a) Creep behavior of epoxy-based adhesive reinforced with nanoparticles for bonded-in timber connection. J Mat Civil Eng 24(7):825–831 Ahmad Z, Ansell MP, Smedley D, Tahir PM (2012b) Effect of environments on the thermal properties of epoxy adhesives modified with nano-and micro-particles for in-situ timber bonding. Indian J Eng Mat Sci 19:343–356 Amran MAF, Ali SA (2015) Green polyurethane adhesives for wood bonding. Adv Mater Res 1115:331–336 Ayrilmis N, Kwon JH, Lee SH, Han TH, Park CW (2016) Microfibrillated-cellulose-modified urea-formaldehyde adhesives with different F/U molar ratios for wood-based composites. J Adhes Sci Technol 30(18):2032–2043 Azamian Jazi M, Ramezani SA, Haddadi SA, Ghaderi S, Azamian F (2020) In situ emulsion polymerization and characterization of pvac nanocomposites including colloidal silica nanoparticles for wood specimens bonding. J Appl Polym Sci 137(15):48570 Baig N, Kammakakam I, Falath W (2021) Nanomaterials: A review of synthesis methods, properties, recent progress, and challenges. Materials Adv 2(6):1821–1871 Baldan A (2012) Adhesion phenomena in bonded joints. Int J Adhes Adhes 38:95–116 Bardak T, Tankut AN, Tankut N, Sozen E, Aydemir D (2016) The effect of nano-TiO2 and SiO2 on bonding strength and structural properties of poly(vinyl acetate) composites. Measurement 93:80–85 Bardak T, Tankut AN, Tankut N, Aydemir D, Sozen E (2017) The bending and tension strength of furniture joints bonded with polyvinyl acetate nanocomposites. Mad Cien Tecn 19(1):51–62 Bardak T, Sozen E, Kayahan K, Bardak S (2018) The impact of nanoparticles and moisture content on bonding strength of urea formaldehyde resin adhesive. Drvna industrija 69(3):247–252 Bedon C, Fragiacomo M (2019) Numerical analysis of timber-to-timber joints and composite beams with inclined self-tapping screws. Compos Struct 207:13–28 Bertolini-Cestari C, Marzi T (2021) Nanocomposites as reinforcement for timber structural elements. In: Branco J, Dietsch P, Tannert T (eds) Reinforcement of timber elements in existing structures. RILEM State-of-the-Art Reports, vol 33. Springer, Cham, pp 79–98 Bertolini-Cestari C, Invernizzi S, Marzi T, Tulliani JM (2013) The reinforcement of ancient timber-­ joints with carbon nano-composites. Meccanica 48(8):1925–1935

174

R. Moya and C. Tenorio

Cazotti JC, Alves GM, Santos AM (2021) Surfactant-free hybrid adhesives based on poly (vinyl acetate) and commercial montmorillonite nanoclays. Polym Bull:1–19. (in press). https://doi. org/10.1007/s00289-­021-­03787-­7 Chaabouni O, Boufi S (2017) Cellulose nanofibrils/polyvinyl acetate nanocomposite adhesives with improved mechanical properties. Carbohydr Polym 156:64–70 Chen H, Nair SS, Chauhan P, Yan N (2019) Lignin containing cellulose nanofibril application in pMDI wood adhesives for drastically improved gap-filling properties with robust bondline interfaces. Chem Eng J 360:393–401 Chen H, Gnanasekar P, Nair SS, Xu W, Chauhan P, Yan N (2020) Lignin as a key component in lignin-containing cellulose nanofibrils for enhancing the performance of polymeric diphenylmethane diisocyanate wood adhesives. ACS Sustain Chem Eng 8(46):17165–17176 Cheng HN, Kilgore K, Ford C, Fortier C, Dowd MK, He Z (2019) Cottonseed protein-based wood adhesive reinforced with nanocellulose. J Adhes Sci Technol 33(12):1357–1368 Clerc G, Brunner AJ, Josset S, Niemz P, Pichelin F, Van de Kuilen JW (2019) Adhesive wood joints under quasi-static and cyclic fatigue fracture Mode II loads. Int J Fatigue 123:40–52 Collett BM (1972) A review of surface and interfacial adhesion in wood science and related fields. Wood Sci Techn 6(1):1–42 Conrad MPC, Smith GD, Fernlund G (2014) Fracture of wood composites and wood-adhesive joints: a comparative review. Wood Fiber Sci 36(1):26–39 Damásio R, Carvalho A, Gomes F, Carneiro A, Ferreira J, Colodette J (2017) Interação de nanocristais de celulose com o adesivo ureia-formaldeído em juntas coladas de Eucalyptus sp. Effect of CNC interaction with urea-formaldehyde adhesive in bonded joints of Eucalyptus sp. Interação 45:169–176 Deka H, Karac N (2011) Bio-based hyperbranched polyurethane/clay nanocomposites: adhesive, mechanical, and thermal properties. Polymers Adv Techn 22(6):973–980 DeVries KL, Adams DO (2002) Chapter 6: Mechanical testing of adhesive joints. In: Pocius AV, Dillard DA (eds) Adhesion science and engineering: surfaces, chemistry and applications. Elsevier, Amsterdam, pp 193–234 Dorieh A, Selakjani PP, Shahavi MH, Pizzi A, Movahed SG, Pour MF, Aghaei R (2022) Recent developments in the performance of micro/nanoparticle-modified urea-formaldehyde resins used as wood-based composite binders: a review. Int J Adhes Adhes 114:103106 Fernandes MF, Da Silva CB, Dornelas J, Junqueira L, Duque B, De Freitas B, Olieira A (2017) Effect of the addition of nanoclay (Na+ montmorillonite) on the urea formaldehyde adhesive in wood bonded joints of Eucalyptus sp. Australian J basic Applied Sci 11(12):51–56 Fleming S (2020) Wood joinery for beginners handbook: the essential joinery guide with tools, techniques, tips and starter projects. USA p 112 Frihart CR, Hunt CG (2010) Adhesives with wood materials: bond formation and performance. In: Wood handbook: wood as an engineering material: chapter 10. Centennial ed. General technical report FPL; GTR-190. US Dept. of Agriculture, Forest Service, Forest Products Laboratory, 2010, Madison, pp 10.1–10.24 Fritz C, Olivera JF (2022) Nanocellulose in heterogeneous water-based polymerization for wood adhesives. Polysaccharides 3(1):219–235 Gadhave RV, Vineeth SK, Mahanwar PA, Gadekar PT (2021) Effect of addition of boric acid on thermo-mechanical properties of microcrystalline cellulose/polyvinyl alcohol blend and applicability as wood adhesive. J Adhes Sci Technol 35(10):1072–1086 Gardner DJ, Tajvidi M (2016) Hydrogen bonding in wood-base materials: an update. Wood Fiber Sci 48(4):234–244 Gardner DJ, Blumentritt M, Wang L, Yildirim N (2014) Adhesion theories in wood adhesive bonding. Rev Adhes Adhes 2(2):127–172 Góral Z, Mastalska-Popławska J, Izak P, Rutkowski P, Gnyla J, Majka TM, Pielichowski K (2021) Impact of melamine and its derivatives on the properties of poly (vinyl acetate)-based composite wood adhesive. Eur J Wood Prod 79(1):177–188

Nanomaterials to Improve the Strength of Wooden Joints

175

Holzer SM, Loferski JR, Dillard DA (1989) A review of creep in wood: concepts relevant to develop long-term behavior predictions for wood structures. Wood Fiber Sci 21(4):376–392 Hunt CG, Frihart CR, Dunky M, Rohumaa A (2018) Understanding wood bonds–going beyond what meets the eye: a critical review. Rev Adhes Adhes 6(4):369–440 Ismita N, Pandey S, Naveen Kumar CK, Khali DP, Kishan Kumar VS, Gupta S (2019a) Exploratory studies on bending strength enhancement of finger jointed timber sections using high nanoclay concentrations in the adhesive. Int J Chem Stud 7(6):1064–1068 Ismita N, Rawat I, Khali DP, Kishan Kumar VS, Gupta S (2019b) Effect of nanoclay addition to urea formaldehyde resin on bending properties of finger jointed timber sections. Int J Recent Sci Res 10:35853–35857 Jasmani L, Rusli R, Khadiran T, Jalil R, Adnan S (2020) Application of nanotechnology in wood-­ based products industry: a review. Nanoscale Res Lett 15(1):1–31 Jawad AJ, Jassim AE, Hadi NJ (2020) Effect of titanium dioxide nanoparticles (TiO2 NPs) on rheological characteristics behavior of poly vinyl acetate (PVAc). NanoWorld J 6(3):61–65 Jiang W, Tomppo L, Pakarinen T, Sirviö JA, Liimatainen H, Haapala AT (2018) Effect of cellulose nanofibrils on the bond strength of polyvinyl acetate and starch adhesives for wood. BioRes 13(2):2283–2292 Joo S, Baldwin DF (2009) Adhesion mechanisms of nanoparticle silver to substrate materials: identification. Nanotechnology 21(5):055204 Kaboorani A, Riedl B (2011) Effects of adding nano-clay on performance of polyvinyl acetate (PVA) as a wood adhesive. Compos A Appl Sci Manuf 42(8):1031–1039 Kaboorani A, Riedl B, Blanchet P, Fellin M, Hosseinaei O, Wang S (2012) Nanocrystalline cellulose (NCC): a renewable nano-material for polyvinyl acetate (PVA) adhesive. Eur Polym J 48(11):1829–1837 Kaboorani A, Riedl B, Blanchet P (2013) Ultrasonication technique: a method for dispersing nanoclay in wood adhesives. J Nanomat (2013):341897 Kamel S (2007) Nanotechnology and its applications in lignocellulosic composites, a mini review. Express Polym Lett 1(9):546–575 Karthäuser J, Biziks V, Mai C, Militz H (2021) Lignin and lignin-derived compounds for wood applications—a review. Molecules 26(9):2533 Kawalerczyk J, Dziurka D, Mirski R, Siuda J, Szentner K (2020a) The effect of nanocellulose addition to phenol-formaldehyde adhesive in water-resistant plywood manufacturing. BioRes 15(3):5388–5401 Kawalerczyk J, Dziurka D, Mirski R, Szentner K (2020b) Properties of plywood produced with urea-formaldehyde adhesive modified with nanocellulose and microcellulose. Drvna industrija 71(1):61–67 Kawalerczyk J, Dziurka D, Mirski R, Siuda J (2021) The reduction of adhesive application in plywood manufacturing by using nanocellulose-reinforced urea-formaldehyde resin. J Appl Polym Sci 138(7):49834 Kwon JH, Lee SH, Ayrilmis N, Han TH (2015) Tensile shear strength of wood bonded with urea– formaldehyde with different amounts of microfibrillated cellulose. Int J Adhes Adhes 60:88–91 Lengowski EC, Bonfatti Júnior EA, Kumode MMN, Carneiro ME, Satyanarayana KG (2019) Nanocellulose-reinforced adhesives for wood-based panels. In: Thomas S, Mishra RK, Asiri AM (eds) Sustainable polymer composites and nanocomposites. Springer, Cham, pp 1001–1025 Li F, Ye C, Huang Y, Liu X, Fei B (2021) Incorporation of in situ synthesized nano-copper modified phenol-formaldehyde resin to improve the mechanical properties of Chinese fir: a preliminary study. Polymers 13(6):876 Liu C, Zhang Y, Wang S, Meng Y, Hosseinaei O (2014) Micromechanical properties of the interphase in cellulose nanofiber-reinforced phenol formaldehyde bondlines. BioRes 9(3):5529–5541 Liu C, Cheng Z, Wang S, Zhang Y, Hosseinaei O (2018) Effects of nanocrystalline cellulose on the micro-creep properties of phenol formaldehyde resin. Mat Res Express 5(12):125019 Lopes TA, Lopes NF, Portilho GR, Andrade FA, de Jesus Silva LB, Castro RVO, Tonoli GHD, Carneiro ADCO (2020) Nanopartículas de lignina e seus efeitos nas propriedades do adesivo

176

R. Moya and C. Tenorio

ureia-formaldeído para colagem de madeira. Engenharia Industrial Madeireira::. Tecnologia, Pesquisa e Tendências, Brasil, pp 218–242 López-Suevos F, Eyholzer C, Bordeanu N, Richter K (2010) DMA analysis and wood bonding of PVAc latex reinforced with cellulose nanofibrils. Cellulose 17(2):387–398 Marini F, Zikeli F, Corona P, Vinciguerra V, Manetti MC, Portoghesi L, Scarascia Mugnozza G, Romagnoli M (2020) Impact of bio-based (Tannins) and nano-scale (CNC) additives on bonding properties of synthetic adhesives (PVAc and MUF) using chestnut wood from young coppice stands. Nano 10(5):956 Marra AA (1992) Technology of wood bonding: principles in practice. Springer, Berlin, p 494 Marzi T (2015a) Nanostructured materials for protection and reinforcement of timber structures: a review and future challenges. Construct Build Mater 97:119–130 Marzi T (2015b) Nanotechnologies for reinforcement and protection of timber structures: innovative nano-coatings. In: Reinforcement of timber structures a state-of-the-art report. Shaker Verlag, Herzogenrath, p 209 Modzel G, Kamke FA, De Carlo F (2011) Comparative analysis of a wood: adhesive bondline. Wood Sci Tech 45(1):147–158 Moon RJ, Frihart CR, Wegner T (2006) Nanotechnology applications in the forest products industry. For Prod J 56(5):4–10 Moya R, Rodríguez-Zúñiga A, Vega-Baudrit J, Álvarez V (2015a) Effects of adding nano-clay (montmorillonite) on performance of polyvinyl acetate (PVAc) and urea-formaldehyde (UF) adhesives in Carapa guianensis, a tropical species. Int J Adhes Adhes 59:62–70 Moya R, Rodríguez-Zúñiga A, Vega-Baudrit J (2015b) Effects of adding multiwall carbon nanotubes on performance of polyvinyl acetate and urea-formaldehyde adhesives in tropical timber species. J Nanomater 16(1):895650 Nautiyal I, Tamkeen Z, Prasad KD, Kishan Kumar VS, Sachin G (2020) Bending strength enhancement of finger joints by inclusion of nanoclay in low concentrations into Urea formaldehyde adhesive. World J Adv Res Rev 5(3):074–080 Noll T (2002) The joint book: the complete guide to wood joinery. Popular Woodworking Books. Charwell Book Inc., New Jersey Oh M, Ma Q, Simsek S, Bajwa D, Jiang L (2019) Comparative study of zein-and gluten-based wood adhesives containing cellulose nanofibers and crosslinking agent for improved bond strength. Int J Adhes Adhes 92:44–57 Oke A, Aigbavboa C, Semenya K (2017) Review of the application of nanotechnology for sustainable construction materials. Adv Eng Res 102:364 Olad A, Anarchi M, Nosrati R (2021) The effect of silica/zeolite-a nanocomposite on the polyvinyl acetate wood adhesive. Scientia Iranica 28(3):1953–1961 Ozcifci A, Kara ME, Kaymakci A (2018) Impact of PF and MUF adhesives modified with TiO2 and SiO2 on the adhesion strength. Wood Res 63(1):75–84 Papadopoulos AN, Kyzas GZ (2019) Nanotechnology and wood science. In: Park SJ, Seo MK (eds) Interface science and technology, vol 30. Academic Press, Cambridge, pp 199–216 Papadopoulos AN, Taghiyari HR (2019) Innovative wood surface treatments based on nanotechnology. Coatings 9(12):866 Peruzzo PJ, Bonnefond A, Reyes Y, Fernández M, Fare J, Ronne E, Paulis M, Leiza JR (2014) Beneficial in-situ incorporation of nanoclay to waterborne PVAc/PVOH dispersion adhesives for wood applications. Int J Adhes Adhes 48:295–302 Pizzo B, Smedly D (2015) Adhesives for on-site bonding: characteristics, testing and prospects. Construct Build Mater 97(30):67–77 Pocius AV (2012) Mechanical tests of adhesive bond performance. In: Pocius (ed) Adhesion and adhesives technology: an introduction. Hanser Publishers, Munich, pp 43–77 Podlena M, Böhm M, Saloni D, Velarde G, Salas C (2021) Tuning the adhesive properties of soy protein wood adhesives with different coadjutant polymers, nanocellulose and lignin. Polymers 13(12):1972

Nanomaterials to Improve the Strength of Wooden Joints

177

Raabe J, Costa TG, Mori FA, Henrique G, Tonoli D, Del Menezzi CHS (2016) Resistance of bonded joints of eucalyptus sp. with resorcinol-formaldehyde resin modified by the addition of silica nanoparticles (Nano-SiO4). WCTE 2016. World Conference on Timber Engineering. Viena Rigg-Aguilar P, Moya R, Oporto-Velásquez GS, Vega-Baudrit J, Starbird R, Puente-Urbina A, Méndez D, Potosme LD, Esquivel M (2020) Micro-and nanofibrillated cellulose (MNFC) from pineapple (Ananas comosus) stems and their application on polyvinyl acetate (PVAc) and urea-­ formaldehyde (UF) wood adhesives. J Nanomat 2020:1393160 Sanghvi Malav R, Tambare O, More AP (2022) Performance of various fillers in adhesives applications: a review. Polym Bull 2022:1–63 Schultz J, Nardin M (1994) Theories and mechanisms of adhesion. In: Pizzi A, Mittal KL (eds) Handbook of adhesive technology. Marcel Dekker, New York, pp 19–33 Shirmohammadi M, Leggate W (2021) Review of existing methods for evaluating adhesive bonds in timber products. In: Engineered wood products for construction. IntechOpen, Vienna, p 30 Stoeckel F, Konnerth J, Gindl-Altmutter W (2013) Mechanical properties of adhesives for bonding wood—a review. Int J Adhes Adhes 45:32–41 Taghiyari HR, Majidi R, Esmailpour A, Sarvari Samadi Y, Jahangiri A, Papadopoulos AN (2020) Engineering composites made from wood and chicken feather bonded with UF resin fortified with wollastonite: a novel approach. Polymers 12:857 Taghiyari HR, Majidi R, Mohseni Armaki SM, Haghighatparast M (2022) Graphene as reinforcing filler in polyvinyl acetate resin. Int J Adhes Adhes 113:103075 Tajvidi M, Gardner DJ, Bousfield DW (2016) Cellulose nanomaterials as binders: laminate and particulate systems. J Renew Mat 4(5):365–376 Tankut N, Bardak T, Sozen E, Tankut AN (2016) The effect of different nanoparticles and open time on bonding strength of poly (vinyl acetate) adhesive. Measurement 81:80–84 Teng TJ, Mat AMN, Sudesh K, Nemoikina A, Jalaludin Z, Ng EP, Lee HL (2018) Conventional technology and nanotechnology in wood preservation: a review. BioRes 13(4):9220–9252 Trache D, Tarchoun AF, Derradji M, Hamidon TS, Masruchin N, Brosse N, Hussin MH (2020) Nanocellulose: from fundamentals to advanced applications. Front Chem 8:392 Ülker O (2016) Chapter 14: Wood adhesives and bonding theory. In: Rudawska (ed) Adhesives– applications and properties. InTech open Books, London, pp 271–288 Veigel S, Müller U, Keckes J, Obersriebnig M, Gindl-Altmutter W (2011) Cellulose nanofibrils as filler for adhesives: effect on specific fracture energy of solid wood-adhesive bonds. Cellulose 18(5):1227–1237 Vineeth SK, Gadhave RV, Gadekar PT (2020) Glyoxal cross-linked polyvinyl alcohol-­ microcrystalline cellulose blend as a wood adhesive with enhanced mechanical, thermal and performance properties. Mater Int 2:0277–0285 Wang Z, Gu Z, Hong Y, Cheng L, Li Z (2011) Bonding strength and water resistance of starch-­ based wood adhesive improved by silica nanoparticles. Carbohydr Polym 86(1):72–76 Wang X, Wang S, Xie X, Zhao L, Deng Y, Li Y (2017) Multi-scale evaluation of the effects of nanoclay on the mechanical properties of wood/phenol formaldehyde bondlines. Int J Adhes Adhes 74:92–99 Wang Z, Li H, Lorenzo R, Corbi I, Corbi O, Fang C (2020) Review on bond properties between wood and fiber reinforced polymer. J Renew Mater 8(8):993 Wibowo ES, Lubis MAR, Park BD (2021) In-situ modification of low molar ratio urea–formaldehyde resins with cellulose nanofibrils for plywood. J Adhes Sci Tech 35(22):2452–2465 Yang W, Rallini M, Natali M, Kenny J, Ma P, Dong W, Torre L, Puglia D (2019) Preparation and properties of adhesives based on phenolic resin containing lignin micro and nanoparticles: a comparative study. Mater Des 161:55–63 Yang R, Sun Y, Zhang X (2020) Application and progress of reinforcement technology for Chinese ancient buildings with wood structure. Geotech Geo Eng 38(6):5696–5701 Younesi-Kordkheili H (2017) Improving physical and mechanical properties of new lignin-urea-­ glyoxal resin by nanoclay. Eur J Wood Wood Prod 75(6):885–891

178

R. Moya and C. Tenorio

Zhang H, Zhang J, Song S, Wu G, Pu J (2011) Modified nanocrystalline cellulose from two kinds of modifiers used for improving formaldehyde emission and bonding strength of urea-­ formaldehyde resin adhesive. BioRes 6(4):4430–4438 Zhang Y, Liu C, Wang S, Wu Y, Meng Y, Cui J, Zhou Z, Ma L (2015) The influence of nanocellulose and silicon dioxide on the mechanical properties of the cell wall with relation to the bond interface between wood and urea-formaldehyde resin. Wood Fiber Sci 47(3):249–257 Zhang X, Sun Y, Liu M, Yang R (2019) Research progress on repair and reinforcement of beams in timber building. InMATEC Web of Conferences EDP Sci 275: 01019 Zidanes UL, Dias MC, Lorenço MS, da Silva AE, Silva MJF, Sousa TB, Mori FA (2021) Preparation and characterization of tannin-based adhesives reinforced with cellulose nanofibrils for wood bonding. Holzforschung 75(2):159–167

Application of Nanomaterials for Wood Protection Tumirah Khadiran, Latifah Jasmani, and Rafeadah Rusli

Contents 1  2  3  4  5 

Introduction  iocide Delivery System for Wood Protection B Metal-Based Nanoparticles for Wood Protection Green Compounds and Nanominerals for Wood Protection Wood Coatings 5.1  Durability Improvement Using Nanocoating 5.2  UV Absorption Using Nanocoating 6  Fire Resistance Improvement Using Nanomaterials 7  Conclusion References

 179  181  183  185  187  188  188  189  191  191

1 Introduction Wood, an anisotropic material, consists of several natural polymers such as cellulose, hemicellulose and lignin (Rowell 2012). The natural polymers become a source of food for biodeterioration agents such as termites, insect borers and decay fungi. The damage of wood caused by the biodeterioration agents leads to immeasurable losses each year. Wood is also susceptible to some external environmental factors like weathering, UV radiation and rainwater. Besides that, wood must also be protected from abrasion, chemicals and fire in order to extend its service life. Figure 1 summarizes the factors affecting the service life of wood.

T. Khadiran (*) · L. Jasmani · R. Rusli Forest Products Division, Forest Research Institute Malaysia (FRIM), Kepong, Selangor, Malaysia e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 H. R. Taghiyari et al. (eds.), Emerging Nanomaterials, https://doi.org/10.1007/978-3-031-17378-3_7

179

180

T. Khadiran et al.

Factors affecting service life of wood

Organisms

Water

Oxygen

Temperature

Fire

Chemicals

Note: Organisms –termites, insect borers, decay fungi, virus, bacteria Fig. 1  Factors affecting the service life of wood

There have been several techniques to preserve wood in order to maintain its quality and expand its service life. Introduction of water repellent agents into the wood structure is one of the simplest techniques. Other techniques include sealing of wood surface structure to prevent the access of air, moisture and organisms. In addition, impregnation of wood structure with biocides (termiticides, insecticides and fungicides) using vacuum-pressure treatment is also an effective technique to protect wood from termites, insect borers and decay fungi attack. This technique is also suitable to impregnate fire retardant chemicals to protect wood from fire hazard. Various wood preservatives have been developed for the purpose of wood protection. Conventional wood preservatives using small-molecule compounds such as creosote, halogenated carbamates, thiazoles and salt-based chemicals, i.e. borates, naphthenates of copper and chromated copper arsenate-based preservatives, have been widely used for wood protection (Krzyzewsky 1987; Betts 2005). However, those conventional wood preservatives are highly toxic and bioaccumulative (Song et al. 2006). They could also be leached out from the treated wood by rainwater, thus contaminating the environment (Hingston et  al. 2001). Furthermore, the presence of the above-mentioned preservatives in wood could limit their recycling perspectives due to it being toxic to human and environment (Adam et  al. 2009; Lin et  al. 2009). Moreover, some of them may negatively affect metal wood connectors, like screws and hinges. Extending the service life of wood using nanomaterials as wood preservatives and fire retardants currently represents an attractive approach for wood protection (Papadopoulos Antonios et  al. 2019). These advanced materials show a good potential to be used as an alternative to the conventional wood preservatives and fire retardants (Hassani et al. 2019; Esmailpour et al. 2020a, b; Taghiyari et al. 2015, 2021a, b). Nanomaterials can protect wood from various factors that affect its quality including organisms, weathering and UV radiation. The potential applications of nanomaterials in extending the service life of wood need to be explored. The present chapter therefore attempts to shed more light on the types of nanomaterials and their potential and role to preserve wood from different perspectives.

Application of Nanomaterials for Wood Protection Fig. 2  Types of supporting materials for preparation of biocides delivery system

181

Synthetic polymer

Support materials Silica

Biopolymer

2 Biocide Delivery System for Wood Protection Biocides are crucial chemicals for the protection of wood from biodeterioration agents, weathering and UV radiation. However, their uncontrolled use and repeated applications have led to non-target effects due to their bioaccumulation in soil and groundwater (Aktar et  al. 2009). Looking for more efficient and safer biocides, controlled-released strategies using biocide delivery systems have been developed as an alternative to conventional approaches. This system functions as carrier for transporting biocides using techniques such as encapsulation. Encapsulation technology offers simple, intelligent and smart technique for designing biocide delivery system with tuned delivery rate and responsive action that able to combat wood biodeterioration in a very efficient manner. Encapsulation protects biocide against leaching and provides a potential environmentally acceptable approach (Sørensen et al. 2010). Biocides inside the small capsules can easily penetrate deeper into the wood structure that is able to prolong the wood protection. Many encapsulation methods using various supporting materials have been extensively developed to prepare biocide delivery system (Fig. 2). Basically, encapsulation is carried out by mixing the biocides with the supporting materials, followed by suspension in water and impregnation of the capsule (polymeric nanoparticles) containing biocides into wood via vacuum-pressure treatment. The polymeric nanoparticle containing biocides is transported into the wood through xylem or phloem. The polymeric nanoparticle acting as carrier releases the biocides slowly into the wood. The nanoparticle also functions as a store for biocides from being directly exposed to the environment. The stability of the polymer nanoparticle suspension is influenced by the charge on the surface, chemical formulation and surfactant selection. On the other hand, the stability of the polymeric nanoparticles is dependent on the polymer matrix. Hydrophobic polymer is inversely proportional to the biocides release rate. As polymer becomes more polar, the release rate of the biocides can be controlled to much

182

T. Khadiran et al.

Table 1  Previous research findings on the development of biocides delivery systems for wood protection Supporting materials Polyvinylpyridine (PVP) PVP-co-styrene, blends of PVP and hyperbranched polyesters (HBPs) Polyethylene glycol

Gelatine-grafted MMA

Silica

Polystyrene/ polycaprolactone homopolymers Alumina

Polystyrene–soybean oil copolymer Β-cyclodextrin derivatives

Biocides Tebuconazole, Chlorothalonil, Kathon 930

Findings The mass loss of treated southern yellow pine exposed to brown rot, Gloeophyllum trabeum and white rot, Trametes versicolor is in the range of 5% to 11% depending on the type of polymer used Garlic essential oil The control efficacy against termite, Tribolium castaneum remained over 80% after 5 months Tebuconazole Nanoparticles afforded protection to treated wood. However, it needs slightly faster release rate to improve the protection performance of treated wood 3-Iodoprop-2-ynyl Accelerated weathering test N-butylcarbamate indicates the capsule containing (IPBC) biocides can prolong the biocidal effect 3-Iodo-2-propynyl Antifouling test indicates the N-butylcarbamate biocides capsules have good protection performance against moulds Carbendazim The carbendazim capsule retention of 0.4 kg/m3 in pinewood is sufficient to increase in 10 times of the decay resistance. However, carbendazim capsules are tended to concentrated on the treated pinewood surface Silver nanoparticles The treated scots pine wood has antifungal properties Allyl isothiocyanate Wood treated with the AITC (AITC) capsules exhibits decrease in mass loss from 45% to 25% and no visible cell wall damage after exposure to white – and brown-rot fungi

References Liu et al. (2001a, c, 2002, 2003), Liu et al. (2001b)

Yang et al. (2009)

Salma et al. (2010)

Sørensen et al. (2010)

Pelto et al. (2014)

Mattos and Magalhaes (2017)

Can et al. (2018) Cai et al. (2019)

slower rate. Nevertheless, if polymer nanoparticles become bigger in size, the suspension becomes less stable. Biocides can be encapsulated in supporting materials through various means like coagulation, precipitation and emulsification. Some studies on the use of chlorothalonil and tebuconazole via polymeric nanoparticle system into solid wood have been

Application of Nanomaterials for Wood Protection

183

reported (Liu et al. 2001a, b). The polymeric nanoparticle matrices used include polyvinylpyridine (PVP), copolymers of PVP and styrene (PVP-co-St), and blends of PVP and hyperbranched polyesters (HBPs). They observed that wood treated with fungicides containing nanoparticles was protected against fungal attack at low dosage of fungicide. Interestingly, the blending of polymer matrices between PVP and HBP showed increased resistance to fungal attack. Table 1 summarizes previous research findings related to the development of biocide delivery system for wood protection.

3 Metal-Based Nanoparticles for Wood Protection Nanoparticles of some of inorganic metals are reported to delay degradation process related to decay fungi or bacteria attack and UV radiation. The use of metal-based nanoparticles is advantageous owing to their high penetration into wood as a result of size and surface area. Higher penetration leads to increased wood protection. A homogeneous distribution and complete penetration of metal-based nanoparticles inside the woods are achievable provided the nanoparticle size is smaller than the pit diameter in the cell wall of the wood. Penetration of metal-based nanoparticles can be further down into capillary of wood if treatment was carried out using pressure treatment technique (Bi et al. 2021). Metal-based nanoparticles that are commonly and extensively used for wood protection include copper, silver and gold. The reason for this common usage is because of their performance and stability after application. Interestingly, the use of copper nanoparticles for wood impregnation leads to increased resistance against termite (Akhtari and Nicholas 2013; Akhtari et al. 2015). Not only that, impregnation work using copper oxide nanoparticles also reported improvement of wood dimensional stability (Jafari et al. 2018). Moya et al. (2014) also reported the advantage of applying silver nanoparticles in which metal-impregnated wood has improved resistance against fungi, water absorption capacity and also dimensional stability. Bak and Nėmeth (2018) conducted studies on various metal nanoparticles (e.g. zinc oxide, zinc borate, copper borate, silver and copper) effect on wood protection and they found that only zinc oxide can solely protect wood after impregnation and leaching. Similar findings were also observed by another author (Mantanis et al. 2014) that compared the influence of zinc – and copper-based nanoparticles on protection against termite and fungi. Nano-zinc oxide was found to have good resistance against both termite and fungi. In another study, wood impregnated with zinc oxide, titanium oxide and silica has improved durability as well as fire resistance (Francés Bueno et al. 2014). Silica nanoparticle has also been typically used for wood impregnation because it is cheap and easily available and gives good silica-impregnated wood performance. Silica nanoparticle is usually incorporated into wood via direct application of sol-gel method as well as chemical grafting. Sol-gel is achieved by mixing silica nanoparticles with solvent to produce transparent dispersion. The silica sol having high surface to weight ratio could penetrate deeper into the wood resulting in better

184

T. Khadiran et al.

silica-­wood composite properties. Impregnation time influences the impregnation performance as longer immersion improves the quantity of silica inside the wood composite material interacting with the hydroxyl group in the wood. The process is similar to covalent modification as briefly mentioned earlier in which the silica sol creates a covalent bond with hydroxyl group abundantly available in the cell wall. The silica-modified wood has good mechanical as well as thermal properties. Another method of incorporating silica nanoparticles into wood is via two-step grafting. For instance, a study by Han et al. (2018) reported that silica nanoparticle-­ grafted wood has improved properties in terms of dimensional stability, low water absorption and increased cell wall thickness. The grafting was achieved by modifying the wood first with itaconic acid followed by grafting silica nanoparticles on itaconic acid-modified wood. In activation step or first step grafting, the anchor chemical, i.e. itaconic acid, was first introduced into the cell wall through reaction with hydroxyl groups. In the second step of grafting, the modified cell wall could easily react with silica nanoparticles forming hydrophobic wood. Although the use of metal-based nanoparticles such as zinc, copper, silver and boron greatly enhances the wood resistance against fungi, the protection against mould is still weak (Lykidis et al. 2016). Interestingly, the use of titanium dioxide on wood has shown promising outcome in which it acts as antibacterial and antifungal (Derakhshankhah et al. 2020). According to Filpo De et al. (2013); Lykidis et al. (2016) and Bak and Nėmeth (2018), titanium oxide (TiO2), zinc oxide (ZnO), zinc borate, metallic silver and copper borate are effective for the protection of wood against white-rot and brown-rot fungi. Titanium oxide (TiO2), cerium oxide (CeO2) and zinc oxide (ZnO) also can be used to protect wood against UV radiation. Titanium oxide (TiO2) and zinc oxide (ZnO) nanoparticles are multifunctional compounds whereby it can function as self-cleaning building material and at the same time can be used to protect wood against white-rot fungi and environment effects (Dong et al. 2017; Harandi et al. 2016). Harandi et al. (2016) studied the antifungal properties of Poplar wood treated with TiO2 and ZnO nanoparticles in polyvinyl butyral nanocomposites. They found that wood treated with 1% nanocomposites did not show antifungal properties, while wood treated with 2% nanocomposites provides protection against fungal. The findings also showed treated wood has a protective effect against ageing factor. Others advantages of TiO2 nanoparticles are that it can decompose the pollutant materials and disinfect the microorganism (Sequeira et  al. 2012). Salla et  al. (2012) used ZnO nanoparticle dispersed in maleic anhydride modified polypropylene to improve the UV-resistant properties of wood surface. The wood coated with polymer containing ZnO exhibited protection against UV light. Janesch et al. (2020) used CeO2 to protect wood from UV light. They developed a simple technique of CeO2 nanoparticle deposition on wood surfaces by using bio-­ based polymer namely chitosan and cationic starch as buildings blocks in a layer-­by-­ layer approach. The result showed that CeO2 offered a significant UV protection effect. Tomak et al. (2018) studied the durability of wood coated with tannin containing zinc and CeO2 nanoparticles against weathering. Colour measurement indicated

Application of Nanomaterials for Wood Protection

185

the combination of tannin and nanometal oxides nanoparticles ensured more colour stability in comparison with reference and coating containing nanometal oxides alone. Semi-inorganic metal such as selenium nanoparticles is also promising as wood preservatives due to their significant antifungal effect and antimicrobial properties (Vrandečić et al. 2020; Pekārkovā et al. 2021). Gablech et al. (2022) used selenium nanoparticles with boron salt-based compound to preserved wood from brown rot, Serpula lacrymans attack. The results obtained indicate selenium nanoparticles have synergistic effect on inhibiting fungi growth. Various approaches can be performed to apply metal-based nanomaterials into wood. A combination of conventional and new modification pathways can be carried out. For example, wood can be first impregnated with silver nanoparticles followed by thermal modification. The purpose of technique combination is to have better modification as thermal modification is known to give adverse effect on mechanical strength. The silver-impregnated wood can increase the amorphous part of cellulose with more crystalline region leading to better end product properties. Another interesting approach is to have multiple nanoparticle impregnation pathway. Cristea et al. (2011) found that a slight improvement in mechanical strength and water vapour diffusion resistance can be observed by mixing zinc oxide with copper nanoparticles. A study by Mohammadnia-afrouzi et al. (2014) also reported that weathering property such as UV ray was also improved through mixed nanoparticles approach. Application of metal-based nanomaterials in wood impregnation leads to increase of wood durability via three (3) possible mechanisms. The first mechanism is related to dissolution of nanometals into fungi cell wall upon entry and causing disturbance to the steady state process of fungal cells which ends up with toxic effect. This behaviour and situation keep the wood intact. Second mechanism involves around interaction of bacteria with nanometals during dispersion process. The interaction results in the deactivation of bacteria or enzyme essential for wood degradation process. The dispersion process needs to be monitored so as to avoid the separation of nanoparticle from the substrate which could make the material become less functional. Last one is related to the inability of the fungi to detect the presence of nanometal. This is particularly happened when copper nanoparticle is used for wood impregnation in which when copper nanoparticles approach the cell wall of the fungus, reactive oxygen species are produced. As a result, these compounds inhibit the fungus attack on wood.

4 Green Compounds and Nanominerals for Wood Protection Preservation of wood using green compounds has gained increasing attention due to their biocide’s properties, sustainability and lower impact on human and environment. Table 2 lists previous research findings on the performance of wood treated with green compounds materials.

186

T. Khadiran et al.

Table 2  Previous research findings on wood treated with green compounds materials Eco-friendly material Essential oil and plant extract (cinnamaldehyde, cinnamic acid, cassia oil, wood tar oil and dodecanal compounds) Plant extract (Acacia mollissima, Schinopsis lorentzii and pinus brutia)

Findings Cinnamaldehyde and cassia acid are effective against brown-rot and white-rot fungi, cinnamic acid only effective against white-rot fungi

The plant extracts can be utilized as alternative wood preservatives against white-rot fungi (Trametes versicolor and Pleurotus ostreatus) and brown-rot fungi (Fomitopsis palustris and Gloeophyllum trabeum) Tannin extract The performance of wood-treated tannin extract showed similar to wood-treated CCB against white-rot fungus (Pycnoporus sanguineus) Wood extractives and linseed Treated wood exhibited higher termite mortality oil (83–100%) Methyl-β-cyclodextrin-­ Treated wood exhibited a significant reduction in essential oil complexes the mass loss from 16–36% to 2–18% after four-week fungi exposure Caffeine Treated Norway spruce wood lasted for 16 weeks against the rot attack and 6 weeks against termite attack. Caffein is leachable (leach from treated wood by water) even in the present of an additional hydrophobic protective layer Tannin acid and tung oil Tannin acid acted as a good UV absorber and free radical scavenger during UV exposure, while tung oil provides a barrier for the penetration of UV light and water on surface of treated wood. It also provided protection against brown-rot fungi (Gloeophyllum trabeum) Metabolic extracts from plant Wood treated with metabolic extracts of PGPR growth-promoting shows a significant inhibition of fungal growth rhizobacteria (PGPR) against decay fungi Konjac flying powder The konjac flying powder showed better activity (by-product produced during against the brown-rot fungi (Gloeophyllum mechanical processing of trabeum) than the white-rot fungi (Trametes konjac flour) versicolour)

References Kartal et al. (2006)

Tascioglu et al. (2013)

Da Silveira et al. (2017) Hassan et al. (2018) Cai et al. (2020) Šimůnkovā et al. (2021)

Peng et al. (2021)

García-Ortiz et al. (2020)

Bi et al. (2019)

Nanominerals such as nano-wollastonite and nano-clay have been shown to improve the resistance of wood against microbial attack (Taghiyari et al. 2014; Bari et  al. 2015). Efhamissi et  al. (2017) were studied the penetration, durability and dimensional stability of poplar wood treated with nano-wollastonite. The results showed that treated wood partially resistant against white-rot fungi. Unfortunately, the efficacy was lost after a short-time leaching. Further finding shows nano-­ wollastonite could not penetrate into the xylem since wood structure serves as a

Application of Nanomaterials for Wood Protection

187

filter against it. However, they found impregnation of nano-wollastonite into wood can improve dimensional stability of wood. Nano-wollastonite can increase the mechanical and physical properties of wood composites. Hassanpoor Tichi et al. (2019) investigated the mechanical, physical and microstructural properties of a wood fibre–cement composite incorporated with different concentration of wollastonite. They found the mechanical properties of wood fibre–cement composites were improved by the 9% wollastonite. Further, the fire resistance of the composite board was improved by increasing the wollastonite concentration. Besides that, the presence of wollastonite in the composite board led to lower water absorption.

5 Wood Coatings Employing traditional coating on wood could relatively improve its strength but at the same time the flexibility and transparency could be affected as well. Other issues related to this could include poor adhesion, durability and so on. One of possible solutions to the existing issue is to incorporate nanoparticles into coating. The use of nanoparticles in coating could lead to exceptionally thin coating end product due to its high surface area characteristic. Furthermore, nanomaterials with unique properties can enhance the performance of wood coatings against biodeterioration agents such as mould and stain fungi, and bacteria, thereby increasing the service life of the wood products. Besides that, properties such as fire resistance, UV resistance, water absorption and mechanical strength are enhanced as well (Bi et al. 2021; Hincapié et al. 2015). The addition of nanoparticles to coating is one way to improve its functionality and end-user value. Due to their morphology, these nanoparticles have extremely high surface-to-volume ratios, allowing them to interact intensely with their environment while maintaining transparency. Incorporation of nanoparticles into coating commonly achieved via two techniques namely mixing and in situ mixing (Zhang et al. 2013). The first technique was relatively a straightforward process in which the nanoparticles are dissolved in a solvent and subjected to mechanical stirring to obtain homogeneous coating. The resulting nanocoating was then used accordingly on wood via brushing or dipping method. On the other hand, in situ mixing usually involves synthesis method where chemicals are mixed and polymerized. Methods such sol-gel deposition and hydrothermal reaction are usually adopted on wood. The latter technique is reported to produce good wood coating adhesion. A study focused on making a superhydrophobic coating was achieved by Wu et al. (2020) on wood that leads to increased dimensional stability. Besides that, the reported work was also claimed as green and environmentally friendly process.

188

T. Khadiran et al.

5.1 Durability Improvement Using Nanocoating The aim of adding nanoparticles in coating is to prevent the growth of various microorganisms like fungi and bacteria by making changes at the molecular level of the products. Many studies have been published to improve the properties of coatings containing nanoparticles (Peres et al. 2019; Weththimuni et al. 2019). Nanosized metal oxides, such as ZnO (Okyay et al. 2015), TiO2 (Chakra et al. 2017) and cerium oxide (CeO2) (Tomak et al. 2018), were described to exhibit strong antimicrobial properties. Nanoadditive layered silicates, layered double hydroxides and nanostructured carbon are also defined as substances with a high surface area. The protective effects of nanostructured ZnO combined with shellac varnish have increased the resistance of wood to UV-induced ageing and growth of common fungal agents. Using a two-step hydrothermal procedure, a homogeneous layer of nanosized ZnO was able to be produced on the wood surface (Weththimuni et al. 2019). The effect of different nanoparticle treatments namely zinc oxide, zinc borate, silver, copper and copper borate on the decay resistance of wood has been investigated (Bak and Nėmeth 2018). Although the most effective treatment was from zinc borate and copper borate, however they also showed a low resistance to leaching. The zinc oxide was found to have the highest concentration (5% m/m) provided effective protection after leaching for against brown and white rot.

5.2 UV Absorption Using Nanocoating It is naturally difficult to avoid wood from being exposed to ultraviolet (UV) rays from solar radiation especially when it is used as outdoor products. As a result, exposed wood surfaces can easily weather, resulting in colour change, cracking, dirt uptake and damage to the wood microstructure. The construction of a coating with UV-resistant properties is an effective way to prevent or lessen the problem of weathering. Several inorganic metal oxides such as ZnO and TiO2 are able to operate as UV stabilizers via light absorption or dispersion (Bi et al. 2021). By decreasing the size of these metal oxides to nanometre scale will enhance the light absorption due to the increase of surface area. Coating wood with these inorganic nanoparticles has been proven to significantly increase UV resistance. The utilization of UV-stabilizing substances can enhance the durability of transparent exterior coatings. Hence, a study on using benzotriazoles, HALS, ZnO and TiO2 nanoparticles and their combinations was conducted to oak wood (Pánek et al. 2019). Surface modification, specifically a combination of benzotriazoles, HALS and ZnO nanoparticles, has been shown to have a good effect on all types of coatings, with the highest benefits being seen in thick-film aqueous acrylic coatings. Similarly, the use of ZnO nanodispersion to coat unmodified and modified wood surfaces reduced photo-discoloration and degradation of wood polymers (Nagarajappa et al. 2020). Photo-bleaching of chemically modified wood caused by

Application of Nanomaterials for Wood Protection

189

light irradiation was increased by applying a nanocoating to the wood’s surfaces. The hydrophobicity and colour stability are among the significant properties for wood to be used outdoor. A two-step spray coating method to apply an epoxy/ZnO coating was found to significantly enhance these properties (Tuong et al. 2019). The enhanced UV absorption capability of the wurtzite hexagonal structure of ZnO found in the epoxy/ZnO coating can be linked to the improved hydrophobicity and colour stability of wood after being coated with epoxy-ZnO coating.

6 Fire Resistance Improvement Using Nanomaterials One of the disadvantages of wood is it has high level of combustibility. Consequently, their use has been limited, with fire safety being a prominent problem in a variety of applications. The flame-retardant characteristics must be seriously considered in order to overcome the inherent flaws as to ensure wood can be utilized in a safe manner. Recently, nanoparticles have been widely used to improve fire resistance properties in wood coating. These particles are used to lower the ignitability of wood, either alone or in combination with conventional fire retardants. Nanoparticles are more effective at low concentrations than other conventional chemicals due to their size and high surface area, which is a huge industrial and economic benefit. The utilization of nanoparticles as coating materials is able to attain high opacity, enhance interaction between the coating and surface, more resilience from combustible and flammable materials and improvise the mechanical, thermal and electrical properties of the materials (Arao and Visakh 2015). Titanium dioxide (TiO2) nanoparticles have been manufactured via various methods to improve TiO2’s efficiency as a non-combustible filler (Nyamukamba et al. 2018). TiO2 have been widely used as fire retardant due to their strong oxidation power, non-toxicity, environmental friendliness, high photo stability, chemical inertness and high thermal stability, as opposed to other conventional fire retardant such as halogenated, phosphorus and nitrogen, which can all be toxic to the environment in the long run (Araby et al. 2021). When compared to the uncoated sample, the TiO2−coated wood was found to be capable of reducing the flammability of the wood and the spread of the flame (Deraman and Chandren 2019). Another metal oxide nanoparticle which has attracted as a good heat-protective barrier for wood is zinc oxide. The addition of ZnO nanoparticle into the intumescent flame-retardant coating of plywood has significantly increased the limited oxygen index values (Nageswara Rao et al. 2020). Inorganic nanomaterial composite coatings are promising materials for endowing wood with flame retardancy behaviour. Chitosan/sodium phytate/TiO2-ZnO nanoparticle (CH/SP/nano-TiO2-ZnO) composite coatings were coated on wood surface through layer-by-layer self-assembly and became an effective flame-­ retardant composite coating on a wood surface without changing the appearance of the wood (Zhou and Yanchun 2020). In an in situ one-step process, nanomagnesium aluminium layered double hydroxide (Mg–Al LDH) was applied to bamboo and

190

T. Khadiran et al.

discovered that total heat release and total smoke production were reduced by 33.3% and 88.9%, respectively, when compared to samples without Mg–Al LDH (Yao et al. 2019). Zinc-aluminium layered double hydroxide (Zn–Al LDH) nanostructures were also applied to wood and the findings showed that the peak heat release rate (PHRR) and total smoke production were reduced by 55% and 47%, respectively, compared to those of the pristine wood (Wang et  al. 2018). Hu and Sun (2021) used nano-CaAlCO3-layered double hydroxide (LDH)-doped intumescent fire-retardant coating for mitigating wood fire hazards. They were carried out fire tests, cone tests and thermogravimetry analysis to investigate the fire-retardant performance of the coating. They found that coating containing 2.2  wt% CaAlCO3-­ LDH exhibited the fire resistance by more than 20 min. Nano-wollastonite and nano-clay were reported to successfully improved the durability of wood against fire (Haghighi Poshtiri et al. 2013, 2014; Taghiyari et al. 2013). Previous study shows that both nano-wollastonite and nano-clay were harmless to human and environment (Padil et al. 2022). They are also not corrosive to metal fasteners and did not have negative effects on hygroscopicity of wood. They are able to protect wood against fire via two main characteristics, i.e. (i) improve thermal conductivity of wood thus can help in preventing fast accumulation of heat in one spot which will eventually prolong the time needed for wood to burn, and (ii) act as passive insulator by providing insulating layer towards penetration of fire into the wood structure; thus, ignition of wood can be delayed (Esmailpour et al. 2019; Taghiyari et al. 2020). Furthermore, they are sustainable and flexible materials that can be used for various applications (Padil et al. 2022). Soltani et al. (2016) investigated the effects of Beech, Poplar and Fir wood impregnated with nano-wollastonite against fire. The woods were heat-treated at two temperatures of 180 °C and 200 °C, respectively. The impregnation process was carried out at a pressure of 3 bars for 30 min. The results indicate that a combination of thermal modification and impregnation with nano-wollastonite improved the fire properties of woods. Nanostructured carbon compounds, such as graphene, have also been shown to have a high potential for application as a fire retardant in wood and wood composites for surface fire protection (Chen et al. 2019; Esmailpour et al. 2020a; Santos et al. 2021). Graphene has received extensive attention over the last decade due to its special structure and exceptional properties (Esmailpour et  al. 2020a). Many studies on graphene as fire retardant materials for wood protection against fire hazards have been previously carried out. Chen et al. (2020) developed hydrophobic aluminophosphate adhesive containing reduced graphene oxide for improvement of water resistance of wood-based board as well as their mechanical properties and fire resistance. The results exhibited an excellent fire resistance properties and smoke suppression ability. Esmailpour et al. (2020a) treated Beech wood using graphene to improve the fire retardancy. The wood treatment was carried out by mixed graphene with water-based paint and followed by brushing on the front and back surface of Beech wood. Six fire tests, i.e. onset on ignition, time to onset of glowing, back-­ darkening time, back-holing time, burn area and weight loss, were performed. The findings demonstrated significant improvement of effects on times to onset of ignition. Besides that, graphene drastically decreased the burnt area. Other study

Application of Nanomaterials for Wood Protection

191

performed by Nine Md et al. (2017) demonstrated that graphene composites with multiple functionalities were successfully developed by growing sodium metaborate (NaBO2.xH2O) crystals into graphene oxide layer. The functionalities make graphene composites work synergistically as a surface binder, a flame-retardant additive and an antibacterial agent. The results of the coating performance tests revealed an outstanding mechanical robustness and the decrease in bacterial colonization up to 99.92%. The flame-retardant performance showed non-flammability, strong intumescent effect and self-extinguishing ability during fire. Fire retardancy impact of graphene was attributed to its very low reaction ability with oxygen, high thermal conductivity in in-plane direction as well as low thermal conductivity in cross-sectional direction (Esmailpour et al. 2020a).

7 Conclusion Nanomaterials for wood protection were extensively studied and developed through various approaches in order to enhance the performance and service life of wood. Based on various research findings, they can be used as alternatives to conventional wood preservatives. Impregnation of wood with nanomaterials makes wood less susceptible to attack from a large variety of biodeterioration agent organisms including decay fungi and insects. Addition of nanomaterials or mixture of nanomaterials can enhance wood protection against weathering (UV radiation and rainwater) and fire hazard. Nanomaterials for wood preservation must satisfy particular characteristics, such as not being readily leached from wood, being toxic to biodeterioration agents but non-toxic or less hazardous to humans and the environment and being able to recycle the wood at the end of its life cycle. Thus, further research is still required to address the above-mentioned areas in order to develop nanomaterial compounds that are industrially applicable.

References Adam O, Badot PM, Degiorgi F, Crini G (2009) Mixture toxicity assessment of wood preservative pesticides in the freshwater amphipod Gammarus pulex (L). Ecotoxicol Environ Saf 72:442–449 Akhtari M, Nicholas D (2013) Evaluation of particulate zinc and copper as wood preservatives for termite control. Eur J Wood Wood Prod 71(3):395–396. https://doi.org/10.1007/ s00107-­013-­0690-­7 Akhtari M, Ghorbani M, Taghiyari HR (2015) Study on the physical and mechanical properties of paulownia wood impregnated with nanosilver and nanocopper. J.  Wood For Sci Technol 21(4):1–13 Aktar MW, Sengupta D, Chowdhury A (2009) Impact of pesticides use in agriculture: their benefits and hazards. Interdiscip Toxicol 1:1–12. https://doi.org/10.2478/v10102-­009-­0001-­7 Araby S, Philips B, Meng Q, Ma J, Laoui T, Wang CH (2021) Recent advances in carbon-based nanomaterials for flame retardant polymers and composites. Compos Part B Eng 212:108675

192

T. Khadiran et al.

Arao Y, Visakh PM (2015) Flame retardancy of polymer nanocomposite. In: Flame retardants : polymer blends, composites and nanocomposites. Springer, Cham, pp 15–44 Bak M, Nėmeth R (2018) Effect of different nanoparticles treatments on the decay resistance of wood. Bioresources 13(4):7886–7899 Bari E, Taghiyari HR, Schmidt O, Ghorbani A (2015) Effects of nano-clay on biological resistance of wood-plastic composite against five wood-deteriorating fungi. Maderas: Ciencia y Tecnologia J 17(1):205–212 Betts WD (2005) The properties and performance of coal-tar creosote as wood preservative. In: Thomson R (ed) The chemistry of wood preservation. Woodhead Publishing, Elsevier, Amsterdam, pp 117–135 Bi Z, Yang F, Lei Y, Morrell JJ, Yan L (2019) Identification of antifungal compounds in konjac flying powder and assessment against wood decay fungi. Ind Crops Prod 140:111650 Bi W, Haitao L, David H, Milan G, Rodolfo L, Ileana C, Ottavia C, Ashraf M (2021) Effects of chemical modification and nanotechnology on wood properties. Nanotechnol Rev 10(1):978–1008. https://doi.org/10.1515/ntrev-­2021-­0065 Cai L, Jeremic D, Lim H, Kim Y (2019) β-Cyclodextrins as sustained-release carriers for natural wood preservatives. Ind Crop Prod 130:42–48 Cai L, Lim H, Nicholas SS, Kim Y (2020) Bio-based preservatives using methyl-β-cyclodextrin-­ essential oil complexes for wood protection. Int J Biol Macromol 147:420–427 Can A, Sivrikaya H, Hazer B (2018) Fungal inhibition and chemical characterization of wood treated with novel polystyrene-soybean oil copolymer containing silver nanoparticles. Int Biodeterior Biodegradation 133:210–215 Chakra C, Raob K, Rajendar V (2017) Nanocomposites of ZnO and TiO2 have enhanced antimicrobial and antibacterial properties than their disjoint counterparts. J Nanomater Biostruct 12:185–193 Chen X, Li J, Gao M, Yue L, Zhou X (2019) Fire protection properties of wood in waterborne epoxy coatings containing functionalized graphene oxide. J Wood Chem Technol 39:1–16 Chen T, Wu Z, Hu X, Aladejana JT, Niu M, Liu Z, Wei Q, Peng X, Xie Y, Wu B (2020) Constructing hydrophobic interfaces in aluminophosphate adhesives with reduced graphene oxide to improve the performance of wood-based boards. Compos Part B 198:108168 Cristea MV, Riedl B, Blanchet P (2011) Effect of addition of nanosized UV absorbers on the physico-mechanical and thermal properties of an exterior waterborne stain for wood. Prog Org Coat 72(4):755–762 Da Silveira AG, Santini EJ, Kulczynsk SM, Trevisan R, Wastowski AD, Gatto DA (2017) Tannic extract potential as natural wood preservative of Acacia mearnsii. Anais da Academia Brasileira de Ciĕncias 89(4):3031–3038 De F, Palermo AM, Rachiele F, Nicoletta FP (2013) Preventing fungal growth in wood by titanium dioxide nanoparticles. Int Biodeterior Biodegrad 85:217–222 Derakhshankhah H, Sajadimajd S, Jafari S, Izadi Z, Sarvari S, Sharifi M, Falahati M, Moakedi F, Muganda WCA, Müller M, Raoufi M, Presley JF (2020) Novel therapeutic strategies for Alzheimer’s disease: implications from cell-based therapy and nanotherapy. Nanomed Nanotechnol Biol Med 24:102149. https://doi.org/10.1016/j.nano.2020.102149 Deraman AF, Chandren S (2019) Fire-retardancy of wood coated by Titania nanoparticles. AIP Conf Proc 2155(1):020022. https://doi.org/10.1063/1.5125526 Dong Y, Yan Y, Ma H, Zhang S, Li J, Xia C, Shi SQ, Cai L (2017) In-situ chemosynthesis of ZnO nanoparticles to endow wood with antibacterial and UV-resistance properties. J Mater Sci Technol 33(3):266–270 Efhamissi D, Ghazan M, Oladi R, Karimimazraehshahi A (2017) Penetrability of nano-­wollastonite into the poplar wood and its effect on wood durability and dimensional stability. Iranian J Wood Pap Ind 8(2):267–282 Esmailpour A, Taghiyari HR, Majidi R, Morrell JJ, Mohammad-Panah B (2019) Nano-wollastonite to improve fire retardancy in medium-density fibreboard (MDF) made from wood fibers and camel-thorn. Wood Mater Sci Eng:1–5. https://doi.org/10.1080/17480272.2019.1641838

Application of Nanomaterials for Wood Protection

193

Esmailpour A, Majidi R, Taghiyari H, Ganjkhani M, Armaki MSM, Papadopoulos A (2020a) Improving fire retardancy of beechwood by graphene. Polymers 12(2):303 Esmailpour A, Taghiyari HR, Majidi R, Babaali S, Morrell JJ, Mohammadpanah B (2020b) Effects of adsorption energy on air and liquid permeability of nanowollastonite-treated medium-density fiberboard (MDF). IEEE Trans Instrum Meas 70:1. https://doi.org/10.1109/TIM.2020.3009355 Francés Bueno AB, Navarro Bañón L, de Morentín M, Moratalla García J (2014) Treatment of natural wood veneers with nano-oxides to improve their fire behaviour. Mater Sci Eng 64(1):12021 Gablech E, Fohlerovā Z, Švec K, Zaleš F, Benada O, Kofroňovā O, Pekārkovā J, Caha O, Gablech I, Gabriel J, Drbohlavovā J (2022) Selenium nanoparticles with boron salt-based compound act synergistically against the brown-rot Serpula lacrymans. Int Biodeter Biodegr 169:105377 García-Ortiz V, Hernández-Soberano C, Martínez-Pacheco M, Ambriz-Parra E, Velázquez Becerra C (2020) Protective effect on wood by metabolic extracts from plan growth-promoting rhizobacteria against decay fungi. Revista Argentina De Microbiologia 52(2):164–166 Haghighi Poshtiri A, Taghiyari HR, Karimi AN (2013) The optimum level of nanowollastonite consumption as fire-retardant in poplar wood (Populus nigra). Int J Nano Dimen 4:141–151 Haghighi Poshtiri A, Taghiyari HR, Karimi AN (2014) Fire-retarding properties of nano-­ wollastonite in solid wood. Philipp Agric Sci 97(1):52–59 Han X, Yin Y, Zhang Q, Li R, Junwen P (2018) Improved wood properties via two-step grafting with itaconic acid (IA) and nano-SiO2. Holzforschung 72(6):499–506. https://doi.org/10.1515/ hf-­2017-­0117 Harandi D, Ahmadi H, Achachluei MM (2016) Comparison of TiO2 and ZnO nanoparticles for the improvement of consolidated wood with polyvinyl butyral against white rot. Int Biodeter Biodegr 108:142–148 Hassan B, Ahmed S, Kirker G, Mankowski ME, ul Misbah Haq M (2018) Synergistic effect of heartwood extracts in combination with linseed oil as wood preservatives against subterranean termite Heterotermes indicola (Blattodea: Rhinotermitidae). Environ Sci Pollut Res 27:3076–3085. https://doi.org/10.1007/s11356-­019-­07202-­7 Hassani V, Taghiyari HR, Schmidt O, Maleki S, Papadopoulos A (2019) Mechanical and physical properties of oriented strand lumber (OSL): the effect of fortification level of nanowollastonite on UF resin. Polymers 11:1884. https://doi.org/10.3390/polym11111884 Hassanpoor Tichi A, Bazyar B, Khademieslam H, Rangavar H, Talaeipour M (2019) Is wollastonite capable of improving the properties of wood-cement composite? Bioresoures 14(3):6168–6178 Hincapié I, Künniger T, Hischier R, Cervellati D, Nowack B, Som C (2015) Nanoparticles in facade coatings: a survey of industrial experts on functional and environmental benefits and challenges. J Nanopart Res 17(7):287 Hingston JA, Collins CD, Murphy RJ, Lester JN (2001) Leaching of chromated copper arsenate wood preservatives: a review. Environ Pollut 111:53–66 Hu X, Sun Z (2021) Nano CaAlCO3-layered double hydroxide-doped intumescent fire-retardant coating for mitigating wood fire hazards. J Build Eng 44:102987 Jafari A, Omidvar A, Rasouli D (2018) The effect of nano copper oxide on physical properties and leaching resistance of wood-polystyrene polymer. J Wood For Sci Technol 25(1):49–59 Janesch J, Czabany I, Hansmann C, Mautner A, Rosenau T, Gindl-Altmutter W (2020) Transparent layer-by layer coatings based on biopolymers and CeO2 to protect wood from UV light. Prog Org Coat 138:105409 Kartal SN, Hwang W-J, Imamura Y, Sekine Y (2006) Effect of essential oil compounds and plant extracts on decay and termite resistance of wood. Eur J Wood Wood Prod 64(6):445–461 Krzyzewsky J (1987) Arsenic creosote wood preservatives. US 4656060 A. Lin LD, Chen YF, Wang SY, Tsai MJ (2009) Leachability, metal corrosion, and termite resistance of wood treated with copper-based preservatives. Int Biodeter Biodegr 63:553–538 Liu Y, Laks P, Heiden P (2001a) Controlled release of biocides in solid wood. I – Efficacy against brown rot wood decay fungus (Gloeophyllum trabeum). J Appl Polym Sci 86:596–607 Liu Y, Laks P, Heiden P (2001b) Controlled release of biocides in solid wood. II  – Efficacy against Trametes versicolor and Gloeophyllum trabeum wood decay fungi. J Appl Polym Sci 86:608–614

194

T. Khadiran et al.

Liu Y, Yan L, Heiden P, Laks P (2001c) Use of nanoparticles for controlled release of biocides in solid wood. J Appl Polym Sci 79(3):458–465 Liu Y, Laks P, Heiden P (2002) Controlled release of biocides in solid wood. III. Preparation and characterization of surfactant-free nanoparticles. J Appl Polym Sci 86(3):615–621. https://doi. org/10.1002/app.10898 Liu Y, Laks P, Heiden P (2003) Nanoparticles for the controlled release of fungicides in wood: soil jar studies using G. Trabeum and T. Versicolor wood decay fungi. Holzforschung 57:135–139 Lykidis C, Bak M, Mantanis G, Nėmeth R (2016) Biological resistance of pine wood treated with nano-sized zinc oxide and zinc borate against brown-rot fungi. Eur J Wood Wood Prod 74:909–911 Mantanis G, Terzi E, Nami Kartal S, Papadopoulos AN (2014) Evaluation of mold, decay and termite resistance of pine wood treated with zinc- and copper-based nanocompounds. Int Biodeter Biodegr 90:140–144. https://doi.org/10.1016/j.ibiod.2014.02.010 Mattos BD, Magalhaes WLE (2017) Design and preparation of carbendazim-loaded alumina nanoparticles as a controlled-release biocide for wood protection. Int Biodeter Biodegr 123:174–181 Mohammadnia-afrouzi Y, Marzbani P, Ahmadinejad A (2014) Investigation on the weathering resistance of poplar wood impregnated with nano ZnO-AgO mixture. Adv Environ Biol 8(10):979–984 Moya R, Berrocal A, Rodriguez-Zuñiga A, Vega-Baudrit J, Noguera SC (2014) Effect of silver nanoparticles on white-rot wood decay and some physical properties of three tropical wood species. Wood Fiber Sci 46(4):527–538 Nagarajappa GB, Rao ANS, Pandey KK (2020) Photostability of acetylated wood coated with nano zinc oxide. Maderas. Ciencia y tecnología 22(3):365–374 Nageswara Rao T, Naidu TM, Kim MS, Parvatamma B, Prashanthi Y, Heun KB (2020) Influence of zinc oxide nanoparticles and char forming agent polymer on flame retardancy of intumescent flame retardant coatings. Nanomater 10(1):42. https://doi.org/10.3390/nano10010042 Nine Md J, Tran Diana NH, ElMekawi A, Losic D (2017) Interlayer growth of borates for highly adhesive graphene coatings with enhanced abrasion resistance, fire-retardant and antibacterial ability. Carbon 117:252–262 Nyamukamba P, Okoh O, Mungondori H, Taziwa R, Zinya S (2018) Synthetic methods for titanium dioxide nanoparticles: a review. In: Itanium dioxide – material for a sustainable environment. IntechOpen, Rijeka, pp 151–1755 Okyay T, Bala R, Nguyen H, Atalay R, Bayam Y, Rodrigues D (2015) Antibacterial properties and mechanisms of toxicity of sonochemically grown ZnO nanorods. RSC Adv 5(4):2568–2575 Padil VVT, Akshay Kumar KP, Murugesan S, Torres-Mendieta R, Waclawek S, Cheong JY, Cernik M, Varma RS (2022) Sustainable and safer nanoclay composites for multifaceted applications. Green Chem 24(8):3081–3114 Pánek M, Hýsek Š, Dvořák O, Zeidler A, Oberhofnerová E, Šimůnková K, Šedivka P (2019) Durability of the exterior transparent coatings on nano-photostabilized English oak wood and possibility of its prediction before artificial accelerated weathering. Nanomater 9(11):1568 Papadopoulos Antonios N, Bikiaris DN, Mitropoulos AC, Kyzas GZ (2019) Nanomaterials and chemical modifications for enhanced key wood properties: a review. Nanomater 9(4):607 Pekārkovā J, Gablech I, Fialovā T, Bīlek O, Fohlerovā Z (2021) Modifications of Parylene by microstructures and selenium nanoparticles: evaluation of bacterial and mesenchymal stem cell viability. Front Bioeng Biotechnol 9:782799 Pelto JM, Virtanen S, Munter T, Larismaa J, Jämsä S, Nikkola J (2014) Encapsulation of 3-iodo-­2propynyl N-butylcarbamate (IPBC) in polystyrene-polycaprolactone (PS/PCL) blends. J Microencapsul 31(5):415–421 Peng Y, Wang Y, Zhang R, Wang W, Cao J (2021) Improvement of wood against UV weathering and decay by using plant origin substances: tannin acid and tung oil. Ind Crop Prod 168:113606

Application of Nanomaterials for Wood Protection

195

Peres ML, de Delucis R, de Amico A, Sandro Campos Gatto Darci A (2019) Zinc oxide nanoparticles from microwave-assisted solvothermal process: photocatalytic performance and use for wood protection against xylophagous fungus. Nanomater Nanotechnol 9:1–8 Rowell RM (2012) Handbook of wood chemistry and wood composites. Taylor & Francis, Boca Raton Salla J, Pandey KK, Srinivas K (2012) Improvement of UV resistance of wood surfaces by using ZnO nanoparticles. Polym Degrad Stab 97:592–596 Salma U, Chen N, Richter DI, Filson PB, Dawson-Andoh B, Matuana L, Heiden P (2010) Amphiphilic core/shell nanoparticles to reduce biocide leaching from treated wood 1 – leaching and biological efficacy. Macromol Mater Eng 295:442–450 Santos L, da Silva D, Morari T, Galembeck F (2021) Environmentally friendly, high-performance fire retardant made from cellulose and graphite. Polymers (Basel) 13(15):2400 Sequeira S, Cabrita EJ, Macedo MF (2012) Antifungals on paper conservation  – overview. Int Biodeterior Biodegrad 74:67–86 Šimůnkovā K, Reinprect L, Nābĕlkova J, Hysek S, Kindl J, Borůvka V, Liskova T, Sabotnik J, Panek M (2021) Caffein – perspective natural biocide for wood protection against decaying fungi and termites. J Clean Prod 304:127110 Soltani A, Hosseinpourpia R, Adamopoulos S, Taghiyari HR, Ghaffari E (2016) Effects of heat-­ treatment and nano-wollastonite impregnation on fire properties of solid wood. Bioresources 11(4):8953–8967 Song J, Dubey B, Jang Y-C, Townsend T, Solo-Gabriele S (2006) Implication of chromium specification on disposal of discarded CCA-treated wood. J Hazard Mater 128(2–3):280–288 Sørensen G, Nielsen AL, Pedersen MM, Poulsen S, Nissen H, Poulsen M, Nygaard SD (2010) Controlled release of biocide from silica microparticles in wood paint. Prog Org Coat 68(4):229–306 Taghiyari HR, Rangavar H, Nouri P (2013) Fire-retarding properties of nanowollastonite in MDF. Eur J Wood Wood Prod 71:537–581 Taghiyari HR, Bari E, Schmidt O (2014) Effects of nanowollastonite on biological resistance of medium density fibreboard against antrodia vaillantii. Eur J Wood Prod 72:399–406 Taghiyari HR, Kalantari A, Ghorbani M, Bavaneghi F, Akhtari M (2015) Effects of fungal exposure on air and liquid permeability of nanosilver – and nano zinc oxide-impregnated Paulownia wood. Int Biodeterior Biodegradation 105:51–57 Taghiyari HR, Esmailpour A, Majidi R, Morrell JJ, Mallaki M, Militz H, Papadopoulos AN (2020) Potential use of wollastonite as a filler in UF resin based medium-density fiberboard (MDF). Polymers 12:1435 Taghiyari HR, Militz H, Antov P, Papadopoulos AN (2021a) Effects of wollastonite on fire properties of particleboard made from wood and chicken feather fibers. Coatings 11(5):518. https:// doi.org/10.3390/coatings11050518 Taghiyari HR, Tajvidi M, Soltani A, Esmailpour A, Khodadoosti G, Jafarzadeh H, Militz H, Papadopoulos AN (2021b) Improving fire retardancy of unheated and heat-treated fir wood by nano-sepiolite. Eur J Wood Wood Prod 79(4):841–849. https://doi.org/10.1007/ s00107-­021-­01679-­1 Tascioglu C, Yalcin M, Sen S, Akcay C (2013) Antifungal properties of some plant extracts used as wood preservatives. Int Biodeterior Biodegradation 85:23–28 Tomak ED, Yazici OA, Sam ED, Gonultas O (2018) Influence of tannin containing coatings on weathering resistance of wood: combination with zinc and cerium oxide nanoparticles. Polym Degrad Stab 152:289–296 Tuong VM, Huyen N, Van Kien NT, NVan D (2019) Durable epoxy/ZnO coating for improvement of hydrophobicity and color stability of wood. Polymers 11:1388 Vrandečić K, Ćosić J, Ilić J, Ravnjak B, Selmani A, Galić E, Pem B, Babir R, Vinković Vrček I, Vinković T (2020) Antifungal activities of silver and selenium nanoparticles stabilized with different surface coating agents. Pest Manag Sci 76(6):2021–2029

196

T. Khadiran et al.

Wang X, Kalali EN, Xing W, Wang D (2018) CO2 induced synthesis of Zn-Al layered double hydroxide nanostructures towards efficiently reducing fire hazards of polymeric materials. Nano Adv 3:12–17 Weththimuni M, Capsoni D, Malagodi M, Licchelli M (2019) Improving wood resistance to decay by nanostructured ZnO-based treatments. J Nanomater 2019:1–11 Wu Y, Wu X, Yang F, JYe (2020) Preparation and characterization of waterborne UV lacquer product modified by zinc oxide with flower shape no title. Polymers 12(3):668 Yang F-L, Li X-G L, Zhu F, Lei C-L (2009) Structural characterization of nanoparticles loaded with garlic essential oil and their insecticidal activity against Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae). J Agric Food Chem 57:10156–10162 Yao X, Du C, Hua Y, Zhang J, Peng R, Huang Q, Liu H (2019) Flame-retardant and smoke suppression properties of nano MgAl-LDH coating on bamboo prepared by an in situ reaction. J Nanomater 1:12 Zhang Z, James M, Hom ND, Jovana R, Constandinos H, Miltiadis T, Nick B (2013) Biofouling resistance of titanium dioxide and zinc oxide nanoparticulate silane/siloxane exterior facade treatments. Build Environ 59:47–55. https://doi.org/10.1016/j.buildenv.2012.08.006 Zhou L, Yanchun F (2020) Flame-retardant wood composites based on immobilizing with chitosan/sodium phytate/nano-TiO2-ZnO coatings via layer-by-layer self-assembly. Coatings 10(3):296. https://doi.org/10.3390/coatings10030296

Nanocellulose in Paper and Board Coating Ayhan Tozluoglu, Saim Ates, Ekrem Durmaz, Selva Sertkaya, Recai Arslan, Orhan Ozcelik, and Zeki Candan

Contents 1  I ntroduction 2  N  anocellulose 2.1  Production Methods of Nanocellulose 2.2  Characterization and Properties of Nanocellulose 2.3  Surface Modification of Nanocelluloses 2.4  Effect of Nanocellulose in Paper and Board Coatings 2.5  Effect of Nanocellulose in Paper and Board Production as an Additive 2.6  Application Drawbacks of Nanocellulose in Paper and Board Production and Coating References

 198  200  201  217  231  254  263  274  275

A. Tozluoglu (*) · R. Arslan Department of Forest Industrial Engineering, Duzce University, Duzce, Turkey Biomaterials and Nanotechnology Research Group & NanoTeam, Istanbul, Turkey e-mail: [email protected] S. Ates · E. Durmaz Department of Forest Industrial Engineering, Kastamonu University, Kastamonu, Turkey S. Sertkaya Department of Forest Industrial Engineering, Duzce University, Duzce, Turkey O. Ozcelik Department of Aerospace Engineering, Ankara Yildirim Beyazit University, Ankara, Turkey Z. Candan Biomaterials and Nanotechnology Research Group & NanoTeam, Istanbul, Turkey Department of Forest Industrial Engineering, Istanbul University Cerrahpasa, Istanbul, Turkey © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 H. R. Taghiyari et al. (eds.), Emerging Nanomaterials, https://doi.org/10.1007/978-3-031-17378-3_8

197

198

A. Tozluoglu et al.

1 Introduction Cellulose, being the most abundant natural polymer on earth, is obtained from plants, microorganisms, bacteria, and some special kind of animals. The annual global production of cellulose is estimated to be 180 million tons. It was determined by Payen in 1838 that 44–45% of cellulose is carbon, 6–6.5% is hydrogen, and the remainder is oxygen (Granström 2009). Cellulose is a linear homopolysaccharide composed of glucose units bonded end to end through carbons C1 and C4 by β-1,4-­ glycosidic linkage (Klemm et al. 2005). Two glucopyranose units, namely cellobiose, constitute the repeating units of this polymer, and the length of cellobiose is approximately 1.03 nm (Fengel and Wegener 1989). Thus, cellulose has a multiscale fibrillated and complex structure which involves crystalline and amorphous regions as morphological (Klemm et al. 2011). The two main resources of cellulose are wood and cotton. For many years, they have been utilized as source of heat, as construction materials, or as raw materials in the manufacturing of specific products in textile and paper industry. Furthermore, cellulose is a versatile material for different products obtained via chemical modification, as witnessed by the variety of commercial cellulose derivatives (Nechyporchuk and Belgacem 2016; Antov et  al. 2020, 2021; Ninikas et  al. 2021; Kristak et  al. 2022). Over the last three decades or so, cellulose has also been used in the production of bio-­based nanomaterials which have at least one dimension in the nanoscale range (i.e., between 1 and 100 nm). Nanocellulose has found many applications in different industrial areas thanks to its high aspect ratio, low density, large surface area, crystallinity, and advanced thermal and mechanical properties (Siró and Plackett 2010). Nanocellulose is generally classified into two basic categories: cellulose nanofibril (CNF) and cellulose nanocrystal (CNC). CNF is produced by mechanical disintegration whereas CNC is obtained via acid hydrolysis (Fig.  1). CNF has a fiber-like structure which includes not only amorphous regions but also crystalline regions of cellulose. Whereas, CNC is in the form of a rod-like structure which consistes only of crystalline regions (Du et al. 2019). Nanocellulose has been used in various applications including optical materials, biomedical materials, reinforcing fillers, and electroconductive materials (Du et al. 2019). On the other hand, the use of nanocellulose in many nonpolar solvents suffers from agglomeration problems because of high hydroxyl groups contained in the structure of the nanocellulose (Kalia et al. 2014). Therefore, various chemical modification treatments and physical interactions are applied in order to convert hydrophilic nanocellulose into a hydrophobic one. Homogeneous dispersibility of nanocellulose in suspension, reactive conjugation of nanocellulose surface, and physical bonding are known to be essential to ensure quality and efficiency of surface modification of nanocellulose. When an organic solvent is especially used for suspension medium, it is used as an effective way of moving from the aqueous medium to the organic solvent because of the hydrophilic properties of nanocellulose surfaces. Whereas, intensive separation treatments such as ultrasonication, high-speed shear are required to homogenize nanocellulose suspension (Eyley and Thielemans 2014). As a consequence, modification of nanocellulose is of considerable importance to

Nanocellulose in Paper and Board Coating

199

Fig. 1  Cellulose nanofibrils (CNF) and cellulose nanocrystals (CNC). (Adapted from Du et al. 2019)

obtain a hydrophobic nanocellulose. In this chapter, different chemical modification methods of nanocellulose are discussed comprehensively. Thanks to their outstanding properties including eco-friendliness, renewability, ease in availability, advanced physical, thermal, and mechanical properties, the nanocelluloses have attracted great attention in pulp and paper industry (Balea et al. 2020). Nanocelluloses have been used in the production of paper/paperboard as a substrate material, as an additive, and in coating of the paper/paperboard. The paper and paperboards which were produced or coated with nanocelluloses exhibit improved properties such as optical clarity, surface smoothness, high impermeability and resistance, high wet and dry strength, low thermal expansion, and high thermal stability (Barbash and Yashchenko 2020). On the other hand, the use of nanocellulose in the production of paperboard as a reinforcement material or as a coating material has been an attractive research topic for researchers. Studies showed that some surface properties like abrasion and scratch resistance, hardness, contact angle, and color stability increased with coating of nanocellulose suspensions (Vardanyan et al. 2014, 2015; Cataldi et al. 2017). In addition, beneficial effects of the use of nanocellulose in the production of wood-based panels have been observed. Nanocelluloses have been generally used as reinforcements in adhesives/bioadhesives, as binders between wood particles, or as powders, or as wood veneers in the production of wood-based composite panels (Candan et  al. 2022; Vineeth et al. 2019; Yildirim and Candan 2021; Yildirim et al. 2021, 2022). It was seen that the boards reinforced with nanocelluloses responded requirements of different industries adequately with regards to physical and mechanical properties such as water absorption, shrinkage/swelling, internal bonding, modulus of rupture,

200

A. Tozluoglu et al.

and modulus of elasticity (Amini et al. 2017; Kojima et al. 2013; Kaboorani et al. 2012; Cheng et al. 2019). In this chapter, the production methods of different nanocellulose types are explained in detail. The characterization and properties of nanocelluloses are clarified and the modification methods of nanocelluloses are introduced comprehensively. Additionally, the effects of nanocelluloses in paper and board coating as well as in paper and board production as additive are explained. Finally, drawbacks of nanocellulose use in the applications of paper and board production and coating are discussed.

2 Nanocellulose Cellulose is one of the most significant chemical components which form the structure of lignocellulosic biomasses and it has been used in different industries such as paper, cardboard and packaging (Jonoobi et al. 2015), textiles and food (Mansouri et al. 2015; Ilies et al. 2022), glue (Khiari et al. 2011), pharmaceuticals, and cosmetics (Olaru et al. 1998) for many years. However, cellulose has gone out of its traditional usage with the discovery of nanocellulose in the last 15–20 years (Kallel et al. 2016). Nanocelluloses are nano-sized cellulosic particles which have properties like high aspect ratio, large surface area, high crystallinity, advanced hydrophobicity as well as optical transparency, low production cost, renewability, sustainability, and biodegradability (Candan et al. 2022; Moon et al. 2011; Shah et al. 2013). Nanocelluloses can be used not only alone but also in combination with different matrix types in nanocomposite films, paper, packaging, textiles, automotive, electronics, biomedical, energy, bioprinting, food, cosmetics, tissue engineering etc. (Candan et  al. 2016; Jasim et  al. 2017; Poyraz et  al. 2017a, b, 2018; Tozluoglu et  al. 2017, 2018a, b; Ul-Islam et al. 2016; Yan et al. 2014; Yildirim and Candan 2021; Yildirim et al. 2021). Cellulose particles with at least one dimension in nanoscale (1–100  nm) are referred to as nanocellulose (Nechyporchuk and Belgacem 2016). Nanocellulose is a general term used to describe nano-sized cellulosic particles. Based on the method of production, the nanocellulose can be classified into two groups: cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs). According to ISO/TS 20477, cellulose nanofibrils are also termed as nanofibrillar cellulose (NFC), cellulose nanofiber (CNF), or nanofibrillated cellulose (NFC). Cellulose nanocrystals are also called nanocrystalline cellulose (NCC) or cellulose nanowhisker (CNW). CNFs are manufactured from purified and bleached pulps via mechanical processes performed with a high-pressure homogenizer, microfluidizer, or grinder. These processes are then followed by mechanical, chemical, or enzymatic pretreatments to facilitate the fibering. On the other hand, CNCs are generally acquired via strong acid hydrolysis from purified and bleached pulps under specific production conditions. As a result of these processes, CNFs containing both amorphous and crystalline regions of cellulose display a reticulated structure, while CNCs containing only the crystalline regions of cellulose have a needle-shaped structure (Jonoobi et al. 2015; Osong et al. 2016). The dimensions of CNCs may vary depending on the cellulose source and hydrolysis conditions (acid type and acid concentration, process time and process

Nanocellulose in Paper and Board Coating

201

temperature, etc.). Nonetheless, CNCs usually have a width of 3–50 nm and a length of 100  nm to several micrometers. In addition, the aspect ratio of CNCs varies between 5 and 50. Similarly, the dimensions and aspect ratios of CNFs also vary with the production procedure. However, according to ISO standard, CNFs generally have a higher aspect ratio (over 10) compared to the CNCs. The width of CNFs varies between 3 and 100  nm and their length can reach up to 100  μm (ISO/TS 20477 2017). Almost all of the natural fiber types can be used as raw materials in the production of nanocellulose. The properties of nanocellulose (e.g., morphological, chemical, and thermal properties and crystallinity) depend on the fiber sources where they are obtained (Jonoobi et al. 2015). The researches have shown that not only wood and woody plants but also annual plants, agricultural wastes, some animals, and bacteria are suitable for being used as raw material in the production of nanocellulose (Hubbe et al. 2008). The use of wood and different types of wood pulp as raw material in the production of nanocellulose is a common practice. The researchers have mostly used bleached kraft pulp (Kekäläinen et al. 2014a, b; Taipale et al. 2010), bleached sulphide pulp (Pääkkö et  al. 2007), sulphide pulp (Wågberg et  al. 2008), and wood powder (Uetani and Yano 2011) as a wood-based raw material in the nanocellulose production. Although wood is an important raw material for nanocellulose production, the use of low-cost raw materials such as annual plant, agricultural waste, some bacteria, and animal sources in nanocellulose production has increased due to the increasing demands of the paper industry, constructional works, and furniture industry. These materials, with their reasonable properties, can be considered as an alternative raw material source to wood in the production of nanocellulose. As such, annual plant and agricultural waste which include wheat stalk, cotton, sugarcane bagasse, jute, coconut shell, bamboo, sisal, pea husk, hemp, rice straw, rutabaga root, kenaf, banana rachis, and soybean hull; bacteria such as Rhizobium, Agrobacterium, Salmonella, Achromobacter, Aerobacter, Sarcina, Acetobacter, Escherichia, and Azotobacter; and marine animals such as tunicate are used in CNF and CNC production (García et al. 2016; Huang et al. 2019; Hubbe et al. 2008). Compared to wood, these sources have some advantages such as low lignin and hemicellulose content as well as low cost. Besides, their usage in the production of nanocellulose remedies to the problem of disposal of these wastes, which are released in excess quantities.

2.1 Production Methods of Nanocellulose 2.1.1 Production of Cellulose Nanofibrils (CNFs) CNFs contain both regular (crystalline) and irregular (amorphous) regions of cellulose microfibers and they are generally obtained from cellulosic sources with different mechanical processes with high shear strength. However, purified and/or bleached cellulose sources are used as raw materials for the production of CNFs. CNF production was introduced in 1983 by Turbak et al. (1983) and Herrick et al.

202

A. Tozluoglu et al.

(1983) by treating a coniferous wood pulp suspension several times in a high-­ pressure homogenizer for the first time. Mechanical processes with high shear strength crumble the cellulose fibers in the transverse direction and, thus, provide the formation of strong fiber networks with nanoscale (Isogai et al. 2011). For separating of cellulose fibers effectively, the shear force applied to the fibers must be higher than the intermolecular hydrogen bond strength. Therefore, CNF production is commonly performed in an aqueous medium to loosen the hydrogen bonds between the fibers and to provide delamination. In addition, cellulose fibers must be treated at very low concentrations (less than 5%) owing to their high capacity of water absorption and hydrophilic properties. Otherwise, suspensions with high viscosity are obtained as a result of the process (Nechyporchuk and Belgacem 2016). 2.1.1.1  Biological and Chemical Pretreatments CNF production by using only mechanical methods leads to high energy consumption. From the 1980s, when the CNF production started first, through the beginning of the 2000s, the high energy consumption was not considered as a major problem. However, in recent years, the applicability of various enzymatic and chemical pretreatments to the production of CNFs has been intensively investigated in order to reduce the high energy requirement and to improve the fibrillation of raw fibers. Nevertheless, such pretreatments affect the structure of the obtained CNFs significantly (Tejado et al. 2012). Figure 2 shows the suspension images of CNFs produced by using different pretreatment methods. 2.1.1.1.1  Enzymatic Hydrolysis It is known that some types of enzymes facilitate the hydrolysis of cellulose and improve fibrillation. Therefore, the enzymatic hydrolysis process has been applied as a pretreatment in CNF production for many years. A group of enzymes called cellulases are used to facilitate the hydrolysis and fibrillation of cellulose fibers in the enzymatic hydrolysis process. Cellulases ((i) endoglucanase, (ii) cellobiohydrolase, and (iii) β-glucosidase) can easily penetrate the crystalline and amorphous regions of cellulose (Fig. 3). As a result of this pretreatment, a decrease in the degree of polymerization of the samples and an increase in the crystallinity index occur (Nechyporchuk and Belgacem 2016). Pääkkö et al. (2007) proposed the following process to separate cellulose fibers: (i) refining process to facilitate the penetration of the enzyme by increasing the swelling and accessibility of the fibers; (ii) enzymatic hydrolysis to facilitate delamination of cellulose fibers; (iii) washing and re-refining processes; and (iv) homogenization process by passing through a microfluidizer 2% concentration fiber suspension with eight repetitions.

Nanocellulose in Paper and Board Coating

203

Fig. 2  CNF suspensions produced with different mechanical methods and pretreatments. (Adapted from Nechyporchuk and Belgacem 2016)

Fig. 3  Schematic representation of the effect of different cellulase types on cellulose. (Adapted from Nechyporchuk and Belgacem 2016)

204

A. Tozluoglu et al.

2.1.1.1.2  Carboxylation with TEMPO-Oxidation Compared to enzymatic pretreatment, chemical pretreatments affect the surface chemistry of the cellulose chain by modifying the internal and external hydrogen bonds. It is known that putting of negatively charged ions on the surfaces of cellulose fibers with carboxylation and carboxymethylation processes significantly facilitates the separation of fibers with electrostatic repulsion or osmotic pressure effect (Bäckström et  al. 2012). Since Davis and Flitsch (1993) reported the use of the 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) for the oxidation of primary alcohol groups of monosaccharides, this method has been one of the most interesting subjects among the researches about oxidation of cellulose. TEMPO ((2,2,6,6-Tetramethylpiperidine-N-oxyl) oxidation is a local oxidation process that converts primary alcohol groups on the cellulose surface to carboxyl groups in slight alkaline conditions (Isogai et al. 2011). De Nooy et al. (1994) investigated the oxidation of polysaccharide primary alcohol groups to carboxylates by using TEMPO, hypobromide, and hypochlorite at basic pH. With this approach, Saito et al. (2006) produced CNF by oxidizing cellulose at carboxyl content up to 1.52 mmol/g. The oxidation reaction was performed with different cellulose sources (bleached sulfite pulp, cotton, tunicate, and bacterial cellulose) at room temperature during a few hours and uniform CNFs of 3–5  nm width were obtained. It was stated that as a result of TEMPO oxidation, not only the production of well separated, individual and fine CNFs but also a significant reduction in energy consumption was noted. For example, when CNF production performed with an energy of 1400 MJ/kg in a highpressure homogenizer was combined with TEMPO oxidation, it was determined that the energy consumption diminished up to 7 MJ/kg (Isogai et al. 2011). The basic principle in the TEMPO/NaBr/NaClO process is the oxidation of cellulose fibers with nitrosonium ion (+N = O), which is formed as a result of the reaction of the TEMPO radical with oxidants (Fig. 4a). As a result of this process, the primary alcohol groups of cellulose are converted to aldehydes which are oxidized to carboxylic groups. It was determined that depolymerization of cellulose occurred during the oxidation reaction. Two phenomena were thought to be related to the depolymerization of cellulose: (i) β-elimination due to the presence of C6 aldehyde groups in alkaline conditions and (ii) separation of anhydroglucose units due to the presence of hydroxyl radicals happened as a side reaction (Isogai et  al. 2011). Various approaches were introduced to prevent the depolymerization which occurs during TEMPO/NaBr/NaClO reaction. Zhao et  al. (1999) reported that TEMPO/ NaClO/NaClO2 system was used for the oxidation of primary alcohol groups of different organic compounds. Saito et al. (2009) applied a similar method for the oxidation of cellulose successfully (Fig. 4). The reaction was conducted under neutral or weak acidic conditions at 60 °C for up to 72 hours. During TEMPO/NaClO/ NaClO2 reaction, initial DP was mostly preserved. Some unconverted aldehyde groups that appear during drying in the oven and cause yellowing of CNFs remain after TEMPO oxidation. These aldehyde groups prevent determination of DP properly from viscosity measurements in copper ethylenediamine (CED) suspension which causes depolymerization of cellulose. Therefore, it was suggested that these steps could be followed: (i) carry out a reduction reaction by using sodium borohydride to convert residual aldehyde groups to alcohols, or (ii) an advanced

Nanocellulose in Paper and Board Coating

205

Fig. 4  Schematic representation of the regional selective oxidation of primary alcohol groups of cellulose: (a) TEMPO/NaBr/NaClO reaction at basic pH, (b) TEMPO/NaClO/NaClO2 reaction at neutral or slightly acidic pH. (Adapted from Nechyporchuk and Belgacem 2016)

oxidation reaction by using sodium chloride to convert aldehyde groups to carboxyls (Mishra et al. 2012; Shinoda et al. 2012). On the other hand, due to the decrease in the friction coefficient between the fibers during the oxidation reaction, a decrease in the strength of the network structure of CNFs was detected (Bäckström et al. 2012). 2.1.1.1.3  Carboxylation with Periodate Chlorite Oxidation Sequential periodate-chloride oxidation of cellulose is used to convert the secondary alcohols of cellulose to carboxyl groups (Kim and Kuga 2001). This method was tried by Liimatainen et al. (2012) as a pretreatment to facilitate the mechanical separation of cellulose in CNF production. During the reaction, the secondary alcohols of cellulose are firstly oxidized to aldehyde groups by using sodium periodate, then they are converted to carboxyl groups by using sodium chloride (Fig.  5). Liimatainen et al. (2012) produced oxidized cellulose containing up to 1.75 mmol/g of carboxyl. Afterwards, the samples were washed, dispersed again in water, and CNFs with 3–5  nm width were gained by passing four times through the high-­ pressure homogenizer. However, it should be noted that this method leads to the opening of the glucopyranose ring which results in 2,3-dicarboxylic acid cellulose. On the other hand, it was determined that the ring opening did not reduce the strength properties of CNFs. On the contrary, the tensile strength and modulus of elasticity of such the films produced with CNF and talc were much higher than the previously stated values for similar materials (Liimatainen et al. 2013a). 2.1.1.1.4 Carboxymethylation In the carboxymethylation process, which is another method applied as a pretreatment in the production of CNF, monochloroacetic acid treatment is performed in the presence of isopropanol to place anionic groups on the cellulose surface. CNF production from carboxymethylated cellulose, which is accepted as a new type of material, was reported by Wågberg et  al. (2008). CNF was produced from

206

A. Tozluoglu et al.

Fig. 5  Carboxylation of cellulose with periodate-chlorite oxidation. (Adapted from Nechyporchuk and Belgacem 2016)

Fig. 6 Carboxymethylation with chloroacetic acid. (Adapted from Nechyporchuk and Belgacem 2016)

carboxymethylated cellulose fibers with a high-pressure homogenizer, and after this process, ultrasonication and centrifugation were applied to remove the remaining fibers that could not be separated (Fig. 6). It was determined that the diameters of obtained CNFs were 5–15 nm, and their lengths were 1 μm. It was stated that carboxymethylated CNFs had lower and more homogeneous dimensions compared to enzymatically pretreated CNFs (Aulin et al. 2009). 2.1.1.1.5 Quaternization In contrast to the carboxymethylation or carboxylation processes used to coat the cellulose with an anionic surface charge, the quaternization process is carried out to cationize the cellulose (Song et al. 2008). This process has been applied as a pretreatment to facilitate the production of CNFs with mechanical methods in recent years. After quaternization, the separation of the fibers becomes easier because of the electrostatic repulsion between the quaternary ammonium cations on the surface of the CNFs (Aulin et al. 2010a). Aulin et al. (2010a) performed the quaternization of bleached sulfide pulp by using (2-3-epoxypropyl) trimethylammonium chloride in the presence of water, isopropanol, and sodium hydroxide (Fig. 7). After washing with distilled water, the fiber suspension at 2% concentration was separated by passing it through a microfluidizer six times. In this study, procured cationic CNFs were used together with anionic homologue, made by carboxymethylation, to produce polyelectrolyte multilayer coatings by using layer-by-layer deposition technique. Quaternized CNF production has also been tried with the help of different chemicals. Ho et  al. (2011) obtained quaternized fibers by using (2-chloroethyl)

Nanocellulose in Paper and Board Coating

207

Fig. 7  Quaternization with (2–3-epoxypropyl) trimethylammonium chloride. (Adapted from Nechyporchuk and Belgacem 2016)

trimethylammonium chloride (chlorocholine chloride) in dimethyl sulfoxide (DMSO) and sodium hydroxide medium, whereas Liimatainen et al. (2014) obtained quaternized fibers by forming a reaction with sequential periodate oxidation and (2-hydrazinyl-­ 2-oxoethyl)-trimethylazanium chloride (Girard’s reagent T), and then they produced CNF by applying mechanical methods to these fibers. 2.1.1.2  Mechanical Treatments High pressure homogenization, microfluidization, and grinding are the most widely used three-step methods with high shear strength in the production of CNF. Because of the changes in the mechanical stresses applied to the fibers, it is thought that CNFs produced with these three different mechanical methods will have different morphological and physical properties. The cellulose suspension moves through a thin gap between the homogenizer valve and the impact ring in the high-pressure homogenizer (Iwamoto et al. 2005), while the cellulose suspension in the microfluidizer passes through a geometric chamber of 100–400 μm width and Z or Y shape with high pressure (Nechyporchuk and Belgacem 2016). On the other hand, the cellulose suspension is subjected to a shear force between a rotating corrugated disc and a fixed disc in the grinder (Hu et al. 2015). The method applied in CNF production was summarized in Fig. 8. High pressure homogenization is used to dismember cellulose fibers mechanically in the production of CNF. CNF production by using a high-pressure homogenizer was first implemented by Turbak et al. (1983) and Herrick et al. (1983). This process was conducted via a Manton-Gaulin homogenizer and with a wood pulp suspension at 2% concentration. Before this process, the cellulosic pulp was treated in a PFI mill at 10000 rpm and the obtained cellulosic material was passed through the homogenizer under 8000 psi pressure at constant temperature at 70–80 °C. As a result, CNFs with diameter less than 100  nm were obtained. The high-pressure homogenization process has been widely used in the production of CNF without any biochemical pretreatment (Wang and Sain 2007) or after different pretreatments

208

A. Tozluoglu et al.

Fig. 8  Three-step method most commonly used in CNF production. (Adapted from Durmaz 2021)

such as enzymatic hydrolysis (Henriksson et al. 2007), carboxylation (Liimatainen et al. 2012), and quaternization (Liimatainen et al. 2014). As an alternative to high-pressure homogenizers, Zimmermann et al. (2004) suggested the use of microfluidizer (Microfluidics Inc., USA) in the production of CNF. With this method, the first application was tried with sulfide pulp suspension by using M-100Y microfluidizer for 60 minutes and at 1000 bar pressure. Previously, the pulp suspension was treated with an Ultra-Turrax (FA IKA) at 24,000 rpm during 8 hours. It was determined that the diameters of obtained CNFs were 20–100 nm and their lengths were a few micrometers. Microfluidizers have been used in the production of CNF without any biochemical pretreatment (Taipale et al. 2010) or after pretreatments like enzymatic hydrolysis (Siqueira et al. 2010a), carboxymethylation (Eyholzer et al. 2010), and quaternization (Ho et al. 2011). The major drawback of the commercial use of high-pressure homogenizers and microfluidizers is the high energy consumption which can reach as high as 70  MW  h/t (Eriksen et  al. 2008). Another disadvantage of these two equipment (especially for microfluidizer) is the clogging problem of the system when cellulosic pulps with long fiber are used (Spence et al. 2011a). Such problems slow down the updating and improvement of CNF production systems consisting of a high-­ pressure homogenizer or a microfluidizer. The grinding process is one of the commonly used methods in the production of CNFs. In this method, Supermasscolloider (MasukoSangyo Co. Ltd., Japan) type grinders are usually preferred. Taniguchi and Okamura (1998) prepared a fiber suspension at 5–10% concentrations from different natural sources and produced CNFs with a diameter of 20–90 nm by passing the suspension through a grinder 10 times. During this process, cellulose pulp is passed between stable and rotating grinding

Nanocellulose in Paper and Board Coating

209

stones. The distance between these stones can be arranged in order to eliminate the clogging problem which may happen in the grinder. The cell wall is separated to its layers with the shear forces between the stones and, thereby, individual CNFs are obtained. The grinding process is very similar to the double stones refining process. However, the main difference is that the distance between the stones is less in the grinding method. Wang et al. (2012) suggested that the gap between the grinding stones be reduced from the zero position to −100 μm to increase fibering efficiency. The zero-movement position of the grinder is the contact position between the two stones before the fiber suspension is placed in the device, and the position is arranged as negative gap after the fiber suspension is loaded to the device. There is no direct contact between the stones even in the negative position of the stones due to the presence of fiber suspension. The refining, which is commonly used in the paper industry, provides separation of the fibers in the aqueous medium by swelling their cell wall. The refining process increases the surface area and volume of the fibers and also makes the microfibrils more accessible for the next biological or chemical processes. Therefore, this process is widely used in the production of large amount of CNFs. However, the refining method reduces the fiber length by shearing and, thus, increases the amount of fine fibers. In the first stages of CNF production, various devices such as disc refiners (Hamada et al. 2012), PFI mills (Henriksson et al. 2007), and Valley-type beaters (Joseleau et  al. 2012) are used to beat cellulosic pulps. Although the refining is desired to be used alone in the production of CNF, the materials obtained via this method are usually a mixture of micro/nanofibril cellulose with a heterogeneous structure. Therefore, refining is generally accepted as a mechanical pretreatment in the first stages of CNF production (Nechyporchuk and Belgacem 2016). Another method used in CNF production is twin screw extrusion method. In this method, cellulose pulp becomes fibrous via interlocking and corotating two screw systems mounted in a closed cylinder. The extrusion method has some advantages compared to high pressure homogenization, microfluidization, and grinding. For example, it is possible to produce CNFs with high solid content of 25–40% with this method (Ho et al. 2015). This can provide various advantages in the storage and transportation of materials produced in high concentrations. In addition, the extrusion method has also been used in the production of nanocomposite materials by obtaining CNF in situ. For instance, Cobut et al. (2014) produced nanocomposite materials with TEMPO-oxidized CNF and thermoplastic starch by using a single screw extruder. It was determined that the average diameter of the CNFs obtained from the extrusion was approximately 30  nm. The disadvantage of the extrusion method is that it is difficult to optimize the profiles of the screws and other production parameters. Optimum screw profiles and process parameters are needed to prevent the degradation of cellulose and to determine the sufficient mechanical force required to separate the fibers. Blending method is generally preferred as a mechanical pretreatment prior to high-pressure homogenization, microfluidization, or grinding processes in the CNF production. It has been noted, however, in the literature that the blending method can be used directly in the CNF production. Uetani and Yano (2011) produced CNFs

210

A. Tozluoglu et al.

with diameters of 15–20 nm from never-dried bleached softwood pulp by using a high-speed blender. When this method was used in CNF production, it was determined that the optimal production conditions were 0.7% for fiber density and 37,000 rpm for mixing speed. Blending for 30 minutes resulted in the same degree of fibrillation and induced less damage on the CNFs when compared to those of ground in Supermasscolloider for one pass. In a similar study, Jiang and Hsieh (2013) applied this method in the production of CNFs from rice straws. They blended bleached rice straw pulps at 37,000 rpm for different times up to 2 hours. The obtained CNFs showed two different size distributions: (i) 2.7 nm diameter and 100–200 nm length, (ii) 8.5 nm diameter and a few micrometers length. Ultrasonication, another method tested in CNF production, is performed by exposing a suspension to ultrasonic waves (greater than 20 kHz). This allows for the change of low- and high-pressure waves; however, it causes formation of small vacuum bubbles and collapse (Wang and Cheng 2009). The ultrasonication process generates strong hydrodynamic shear forces that can be used to delaminate the cell walls of the fibers. Some researchers have used this method to produce CNF without any biochemical pretreatment (Wang and Cheng 2009) or after TEMPO oxidation (Saito et al. 2006). After ultrasonication, the cellulose suspensions are centrifuged and CNFs are recovered from the supernatant. Another method, called “Cryocrushing,” used in the production of CNFs was introduced by Dufresne et al. (1997). In this method, cellulosic pulp is frozen by using liquid nitrogen and it is compressed by applying high shear force. Ice crystals under mechanical effect exert pressure to the cell walls, and thus they cause disintegration of these layers. Dufresne et al. (1997) produced CNFs at 500 bar pressure with a high-pressure Manton-Gaulin homogenizer from cryocrushed sugar beet pulp as a pretreatment. This method has been mostly tried for the fibrillation of agricultural products (Alemdar and Sain 2008a, b; Wang et al. 2007a). The steam explosion method is used as a pulp preparation process for the extraction of cellulose fibers from lignocellulosic materials. However, CNF production has also been conducted with this method from natural resources such as pineapple leaves, banana fibers, wheat stalk, and jute. During the steam explosion process, cellulosic pulp is exposed to pressurized steam for a short time. This process is followed by a rapid release of pressure and it provides disintegration of the cell walls of the fibers. Besides, this application results in hydrolysis of significant amounts of hemicellulose to essential sugars and water-soluble oligomers and depolymerization of some lignin (Nechyporchuk and Belgacem 2016). Ball milling is yet another technique emerged recently for the production of CNFs. In this method, the cellulose suspension is put in a cylindrical container filled with ceramic, zirconia (zirconium dioxide), or metal balls. As the container rotates, the cellulose is crumbled by the high-energy collisions between the balls. Kekäläinen et al. (2015) produced CNFs with high solid content (≥50%) from TEMPO-oxidized bleached hardwood kraft pulp via ball milling. In this study, the effects of grinding time, moisture content, and carboxylic charge on the pulp separation process and the morphology of CNFs were investigated. With this method, individual CNFs with a diameter of 3.2 nm and nanofibril bundles with diameters of 10–150 nm were

Nanocellulose in Paper and Board Coating

211

obtained. Therefore, the quality and homogeneity of produced CNFs remain as a major problem for this method. In “Aqueous Counter Collision” (ACC) method, which is another method in CNF production, cellulosic aqueous suspensions coming out of two different nozzles under high-pressure collide and crumble, and thus form into moist CNF powders. Kose et al. (2011) produced individual CNFs with a diameter of 30 nm from a suspension of bacterial cellulose at concentrations of ≤0.4% by using the ACC method (in 80 times pass and 200 MPa pressure). After this treatment, the cellulose Iα crystal phase gets converted into cellulose Iβ phase, while the crystallinity index remained above 70%. The disadvantage of this method is that the dimensions of the cellulosic material to be processed must be smaller than the nozzle diameter of the device (150 μm) in order to prevent clogging. CNF production with traditional mechanical methods is a process requiring high energy (Tejado et al. 2012). Many studies have been performed to reduce the energy consumption in CNF production. The most viable option to date is considered to be the application of mechanical treatments in combination with either a chemical or an enzymatic pretreatment. In this way, the energy consumption can be decreased from ≈100 kWh/kg to 1–2 kWh/kg (Siró and Plackett 2010). While these physicochemical pretreatments contribute to the reduction of total energy consumption significantly, they can also increase the production cost and result in chemical modification of cellulose. This situation may lead to changes in the structure of CNFs and, thus, cause them to gain properties which are not desirable in their application areas (Tejado et al. 2012). Therefore, it can be stated that the use of available equipment efficiently and applying the combination of different mechanical methods properly are very important in order not to degrade the structure of CNFs (Naderi et al. 2015). 2.1.2 Production of Cellulose Nanocrystals (CNCs) Cellulose nanocrystals (CNCs) are generally obtained from a purified cellulose resource under certain production conditions by removing the amorphous regions in the cellulose via acid hydrolysis method and retaining the nano-sized crystalline regions. After this process, centrifugation and dialysis steps are carried out respectively in order to clean the obtained suspensions, and then ultrasonication is performed to provide the distribution of CNCs in water. However, minor changes can be made in the procedure especially during the acid hydrolysis process depending on the used raw material source (Dufresne 2017; Habibi et al. 2010). The procedure used in CNC production is summarized in Fig. 9. CNCs are obtained from cellulose fibers generally via acid hydrolysis method and, rarely, via enzymatic hydrolysis method. Acid hydrolysis process requires harsh hydrolysis conditions involving a high concentration of acid treatment, while enzymatic hydrolysis requires a longer processing time. During the hydrolysis process, the amorphous regions of cellulose are more easily destroyed than the

212

A. Tozluoglu et al.

Fig. 9  General procedure applied in CNC production. (Adapted from Durmaz 2021)

crystalline regions. This ends up in removal of the amorphous regions and preservation of the crystalline regions, and thus rice-shaped CNCs were obtained (Fig. 10). In retrospect, the first production of CNCs was carried out by Nickerson and Habrle (1947) with hydrolysis of cellulose with hydrochloric acid and sulfuric acid. In 1951, Rånby prepared colloidal CNC suspensions from wood fibers via sulfuric acid hydrolysis (Rånby 1951). Mukherjee and Woods (1953) determined that the dimensions of needle-shaped particles obtained via sulfuric acid hydrolysis were nano-sized with the help of X-ray dispersion and electron microscopy. In another study, Marchessault et al. (1959) found that CNC suspension showed birefringence. In the later years, new and different methods such as enzymatic hydrolysis, ionic liquid, solid acid hydrolysis, organic acid hydrolysis, oxidation, and subcritical hydrolysis were tried in the production of CNCs. 2.1.2.1  Mineral Acid Hydrolysis Hydrolysis with mineral acids is the most common method used in the production of CNCs. Many different cellulose sources such as tomato peel, palm waste, rice husk, and waste fabric scraps have been used in this process. The hydrolysis process is usually conducted in the presence of strong mineral acids (6–8 M) at a suitable temperature, treatment time, and acid/cellulose ratio. The mineral acids used in the process include sulfuric acid, hydrochloric acid, phosphoric acid, hydrobromic acid, and their mixtures (Kargarzadeh 2017; Xie et al. 2018). Hydrolysis involves the penetration of acid hydronium ions into amorphous regions of the cellulose chain. The obtained CNCs have a high resistance to acid treatment (Dufresne 2017). Compared to other acid types, the use of hydrochloric acid (HCl) in CNC production causes aggregation of CNCs more easily in the water (Araki et  al. 2001). Sulfuric acid is the most widely used type of acid, as it creates negative particle charges on the surface of CNCs, which in turn facilitates the formation of more

Nanocellulose in Paper and Board Coating

213

Fig. 10 (a) Amorphous and crystalline regions of cellulose microfibril chain, (b) Cellulose nanocrystals obtained after acid hydrolysis treatment. (Adapted from Xie et al. 2018)

stable suspensions. When sulfuric acid is used as a hydrolysis agent, it grafts anionic sulfate half ester groups (OSO3–) onto the surface of the cellulose (Habibi et al. 2010). The colloidal stability of the aqueous suspension prevents aggregation of the CNCs (Lu et al. 2014a). In general, the hydrolysis process is performed at an acid concentration of 60–65%, at a reaction temperature of 40–50 °C, and a reaction time of 30–60 minutes. The yield, morphological, thermal, and crystallinity properties of the CNCs can be improved by changing the reaction conditions such as acid concentration, reaction time, and temperature (Xie et  al. 2018). Hydrochloric acid, another type of mineral acid, is also a common acid type used in the production of CNCs. Acid concentration, reaction temperature, and reaction time are 60 ml g−1, 110  °C, and 2 to 4  hours, respectively (Yu et  al. 2013). Because the surfaces of CNCs are uncharged, CNCs obtained with hydrochloric acid hydrolysis easily agglomerate in water. However, their thermal stability is higher than that of CNCs obtained with sulfuric acid. Phosphoric acid (pKa = 2.12), which is accepted as a medium-strong acid, can be used in the production of CNCs with high thermal stability and stable suspension properties (Camarero Espinosa et al. 2013). Similarly, hydrobromic acid hydrolysis was applied before ultrasonication in the production of CNCs with high crystallinity (Sucaldito and Camacho 2017). Spherical CNCs with good suspension stability and advanced thermal properties were produced with different acid systems such as sulfuric acid/hydrochloride (Zhang et  al. 2007) and hydrochloric acid/nitric acid (Cheng et al. 2017). Mineral acid hydrolysis is usually accepted as a simple method in CNC production and there are many pilot-scale production facilities (e.g., CelluForce Canada (1 ton/day)). However, this method still has some disadvantages. Corrosion occurs in the equipment used in production owing to high acid concentration, and this leads to increased production costs. Another problem is that high amounts of waste acids and other polluting chemicals are released during hydrolysis and their disposal and recovery are very difficult. Due to these reasons, the development of eco-friendly

214

A. Tozluoglu et al.

and low-cost CNC production methods is of vital importance from the perspective of nanomaterials science (Zhu et al. 2016). 2.1.2.2  Solid Acid Hydrolysis Solid acid hydrolysis method is another method that has been utilized in the CNC production. In this method, cation exchange resin, phosphotungstic acid, phosphotungstic acid/acetic acid, etc., systems have been applied. Research efforts showed that the crystallinity values of CNCs obtained via cation exchange resin hydrolysis were higher than those obtained via sulfuric acid hydrolysis. Besides, the recoverability of cation exchange resins reveals that this hydrolysis method can be a promising approach in CNC production. Similarly, phosphotungstic acid can also be recovered with ethyl ether extraction. Because solid acid hydrolysis method is a three-stage solid/liquid/solid process, reaction efficiency is low and reaction time is relatively longer compared to mineral acid hydrolysis method. However, the reaction efficiency can be increased with specific physical applications (e.g., microwave or ultrasonication) or with suitable catalysts. Because solid acid hydrolysis is conducted in mild conditions, corrosion in equipment is low and solid acids are recycled. In addition, the efficiency of CNCs obtained by this method was found to be higher. However, CNC production via solid acid hydrolysis method has been exclusively at the level of laboratory-scale research efforts (Xie et al. 2018). 2.1.2.3  Organic Acid Hydrolysis Recently, organic acids have been playing a key role in the CNC production due to their moderate, recyclable, eco-friendly, and low corrosive properties. However, because organic acids are included in the weak acid group, high reaction temperature and time should be preferred in order to increase the efficiency of the hydrolysis process. In this method, different types of organic acids such as formic acid, dicarboxylic acid, maleic acid, citric acid/hydrochloric acid, 2-bromopropionic acid, 3-mercaptopropionic acid, 4-pentenoic acid, and 2-propinoic acid are used. Generally, organic acid hydrolysis in CNC production is considered more sustainable and environmentally friendly than mineral acid hydrolysis. Therefore, the belief that CNC production will be industrialized with organic acid hydrolysis has been increasing day by day (Xie et al. 2018). 2.1.2.4  Enzymatic Hydrolysis Enzymatic hydrolysis is one of the methods used in the production of CNCs. Cellulase is a multicomponent enzyme system and its active components are endoglucanase, cellobiohydrolase, and 𝛽-glucosidase. Endoglucanase affects the amorphous regions of cellulose to hydrolyze the 𝛽-1,4 glycosidic bond. Thus, long chain

Nanocellulose in Paper and Board Coating

215

cellulose molecules are converted into short cellulose molecules. Cellobiohydrolase influences the ends of linear cellulose molecules to destroy the crystalline regions of cellulose, while 𝛽-glucosidase is used to hydrolyze cellulose to glucose (Lynd et al. 2002). The destruction of the crystalline regions of cellulose by cellobiohydrolase should be avoided as much as possible in the production of CNC via enzymatic hydrolysis. Therefore, three components of cellulase must be separated from each other. It was determined that CNCs obtained by enzymatic hydrolysis showed excellent distribution and homogeneity. Besides, it was observed that spherical CNCs can also be produced from the enzymatic hydrolysis method combined with the ultrasonication process (Meyabadi et al. 2014). In short, when it is compared to mineral acid hydrolysis, enzymatic hydrolysis method is considered as an eco-­ friendly practice. However, the production conditions of this method are very challenging, the reaction time is long, and the production efficiency is low. Nevertheless, CNC production with enzymatic hydrolysis is considered a promising method (Xie et al. 2018). 2.1.2.5  Oxidation Degradation The hydroxyl groups on cellulose are highly reactive, and these groups are easily oxidized to aldehyde, ketone, and carboxyl groups via strong oxidants in oxidative degradation process. Thus, their structure is destroyed and the degree of polymerization decreases. Therefore, some researchers have successfully produced CNC by using the oxidation method. Yang et al. (2013a) applied a two-step oxidation process in the production of CNCs. First, softwood pulp was oxidized with sodium periodate and then second oxidation process with sodium chloride was applied. Finally, CNCs were obtained by applying the centrifugation step. It was determined that CNCs with carboxyl groups on their surface had high crystallinity index and high charge density. Ammonium persulfate is a chemical used as an oxidation agent in the production of carboxylated CNCs (Kasiri and Fathi 2018). It was determined that CNCs produced via ammonium persulfate process had higher charge density, crystallinity index, suspension clarity, and permeability compared to CNCs produced via sulfuric acid hydrolysis (Mascheroni et al. 2016). In addition, CNCs obtained via this method are spherical and their crystal structures are in the form of cellulose II (Cheng et  al. 2014). With ammonium persulfate process, CNC can be obtained without any pretreatment to remove lignin from agricultural raw materials such as hemp, flax, and straw. The reason for this is that in addition to the oxidative property of ammonium persulfate, it also has the ability to remove lignin. Another chemical used in the production of carboxylated CNC with oxidation method is TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl) (Peyre et al. 2015). However, only the subfractions of the raw materials were converted to CNC, while the remaining oxidized cellulose remained in large dimensions in this method. These results revealed that TEMPO oxidation was not as effective as ammonium persulfate oxidation in CNC production. However, CNCs obtained with TEMPO oxidation were highly

216

A. Tozluoglu et al.

carboxylated (Okita et  al. 2010) and this enabled the functionalization of CNCs (Ifuku et al. 2009). Consequently, it was determined that CNCs obtained via oxidation method had a higher yield compared to mineral acid hydrolysis and enzymatic hydrolysis. However, a large amount of oxidant is consumed in the reaction process and the reaction time is too long. Besides, large amounts of water and energy are consumed. This makes the production costs of CNCs to be very high (Xie et al. 2018). 2.1.2.6  Ionic Liquid Method Ionic liquids are a kind of organic salt solution with a low melting point (less than 100  °C) consisting of organic cations and other anions. Ionic liquids have some advantages in terms of chemical and thermal stability, nonflammability, low vapor pressure when compared with conventional solvents. Ionic liquids are also called as “green solvent” (Earle and Seddon 2000). Because of such unique properties, ionic liquids have been commonly used in the separation of cellulose and CNC production recently. In studies with this method, ionic liquids such as [BMIM]HSO4, [BMIM]Cl, [EMIM][OAc], and TBAA/DMAc were tested. The method consists of three main steps. First, CNCs are produced with sulfuric acid hydrolysis, then CNCs are dispersed in an organic solvent, and finally CNCs are modified hydrophobically. Ionic liquids are regarded to have a great potential in the production of CNCs due to their reusability and their role in the preparation of functional CNCs. However, the most important disadvantage of ionic liquids is that they are expensive and have some toxic properties (Xie et al. 2018). 2.1.2.7  Other Methods Apart from the above-mentioned hydrolysis methods, there are also other methods which have been successfully used in the production of CNCs. For instance, CNCs with high thermal stability and good dispersion properties were obtained from mechanically treated wood microfibers by using a deep eutectic solvent (DES) produced with choline chloride and oxalic acid. Compared to the production yield obtained from sulfuric acid hydrolysis, the CNCs obtained via DES method were found to have a higher yield (68–78%). Besides, these solvents are recyclable, biodegradable, and eco-friendly materials. Nonetheless, the reaction steps proceed slowly in this method. For this reason, DES method needs to be followed by a mechanical separation process, and today this method is performed only on a laboratory scale (Sirviö and Visanko 2017). In another study, Nelson et al. (2016) stated that different types of nanocellulose can be produced from lignocellulosic materials at low costs with the AVAP (American Value Added Pulping) technology developed by API (American Process Inc.). Besides, hydrophilic/hydrophobic CNCs and CNFs with lignin content at certain amount can be prepared with this method. In the AVAP method, sulfur dioxide (SO2) and ethanol were used as a pretreatment and, thus, lignin, hemicellulose as

Nanocellulose in Paper and Board Coating

217

well as amorphous regions of cellulose were removed from cellulosic biomass. SO2 was used as a delignification agent, whereas ethanol was used to dissolve resin and extractives and also to reduce the degradation of crystalline regions of cellulose. In addition, this method did not cause any swelling or destruction in the crystal region of cellulose. With the AVAP method, hydrophobic and dimensionally adjustable CNCs can be produced and these products can be evaluated in many different areas. In addition to these chemicals, transition metals such as Fe(III), Al(III), Ni(II), Co(II), and Mn(II) have been tested in the CNC production from lignocellulosic biomass, but they have not been discussed in detail (Xie et al. 2018). The type of cellulose source is regarded as the main factor affecting the properties of CNCs, whereas the production method is considered as the main factor affecting the properties of CNFs. Although there are some problems that need to be solved in the production of nanocellulose, industrial companies have already achieved large-scale production and taken important steps towards the commercialization of the nanocellulose. Researchers and various companies have initiated to move nanocellulose production from laboratory scale to industrial scale in recent years. Table  1 displays the production capacities and methods used by different companies that produce CNC and CNF for 2018.

2.2 Characterization and Properties of Nanocellulose Nanocelluloses are produced as suspensions with very low solid content (less than 5%). Therefore, nanocelluloses have appearance of high viscosity gel or suspension depending on dimensions and concentration of the material (Fig.  11). However, nanocelluloses are commercially sold in powder form or in suspensions of high concentrations. CNCs are sold as 6–12% suspension or freeze-dried powder, while CNFs are commercially sold as high-concentration gels or pulps at 1–25% concentration. However, CNFs cannot be sold as freeze-dried or spray-dried form due to redispersibility problem (Foster et al. 2018). Determining the properties of nanocellulose in suspension form is important, but it is very difficult. Determining the properties of dry nanocellulose is comparably easier. On the other hand, the moisture content of 2–5% can influence the measurement of certain properties such as surface area of nanocellulose. Different methods have been used to determine the properties of nanocellulose, but most of these methods involve the conversion of suspended nanocellulose species into other dry types of nanocellulosic materials such as film or foam (Foster et al. 2018).

218

A. Tozluoglu et al.

Table 1  Production methods and capacities of companies producing CNC and CNF (2018, tons/ year, dry matter) (TAPPI, Cellulose Nanomaterials Production Update, 2018) Producer CNC CelluForce, Canada American Process, USA Melodea, Sweden Alberta Innovates, Canada U.S. Forest Products Lab, USA Blue Goose Biorefineries, Canada FPInnovations, Canada Hangzhou Yeuha Technology Co., China Sweetwater Energy, USA Tianjin Haojia Cellulose Co., Ltd., China CNF Nippon Paper, Japan University of Maine, USA American Process, USA CelluComp, United Kingdom Chuetsu Pulp and Paper, Japan Oji Paper, Japan Sugino Machine, Japan Seiko PMC, Japan SAPPI, Netherlands VTT, Finland Tianjin Haojia Cellulose Co., Ltd., China Dai-ichi Kyogo (DKS), Japan U.S. Forest Products Lab, USA

Process

Capacity

Sulfuric acid hydrolysis SO2 fractionation Sulfuric acid hydrolysis Acid hydrolysis Sulfuric acid hydrolysis Catalytic conversion Sulfuric acid hydrolysis Proprietary Reactive extrusion Modified and unmodified

260 130 35 5 3 2 Pilot Pilot Pilot Pilot

TEMPO, carboxylated Mechanical SO2 fractionation Chemical pretreatment Aqueous counter collision Phosphate esterification Oblique collision Modified hydrophobic Chemical Chemical, enzymatic TEMPO, carboxylated TEMPO TEMPO, mechanical

560 260 130 100 100 40 26 24 5 5 3 1  C2-OH (Fig. 14). During esterification, because of the stearic hindrance of the nanocellulose surfaces, all of the C3-OH and C2-OH bounds are not modified completely. Also because of the mild condition, crystalline structure of cellulose molecules is not degraded and degree of substitution would be higher. (Gan et al. 2017). According to Wang et al. (2018), the main esterification reactions are divided into five groups; (1) norganic esterification: uses inorganic acids such as sulphuric and phosphoric acids, as esterification agents. Due to the negatively charged ester groups, this process produces stable dispersibility of nanocelluloses in water, (2) Fischer esterification: some acids such as acetic acid, butyric acid, citric acid, malic acid, and malonic acid were used with hydrochloric acid catalyst, (3) Mechanochemical esterification: as esterification agent succinic anhydride, n-dodecyl succinic anhydride, hexanoyl chloride, and pentafluorobenzoyl chloride+pyridine were used, it aims to ball mill fibers in organic solvents such as dimethylformamide (DMF) or (Tetrahydrofuran) THF and to produce CNFs with tunable properties using esterifying agents such as chloride or anhydride derivatives (Huang et al. 2019). (4) Transesterification: vinyl acetate, vinyl cinnamate, or canola oil fatty acid methyl ester was used with potassium carbonate catalyst. A new approach for the acetylation of NCCs is transesterification of vinyl acetate with DMF at 95 °C, which was studied by Cetin et al. (2009). They reported that increasing the reaction time resulted in the higher ratio of acetylation, smaller particle dimensions, and lower crystallinity in the modified NCCs. (5) Solvent-free esterification: in this processes palmitoyl chloride, iso-octadecenyl succinic anhydride, n-tetradecenyl succinic anhydride, and aromatic carboxylic acids were used as esterification agents. Berlioz et al. (2009) reported a highly efficient solvent-free synthetic method for surface esterification of nanocelluloses. The reaction of fatty acids such as palmitoyl chloride was carried out on freeze-­dried or supercritical carbon dioxide dried nanocellulose substrates at a temperature ranging from 160 °C to 190 °C and at low pressure. Esterification proceeds from the surface of the substrate towards the center of the crystal region. Among the esterification reactions, acetylation of the nanoparticle surfaces is the most effective and the simplest method due to the fact that chemicals used in this method are very common and not too expensive (Lee and Bismarck 2014). Acetylation of the nanocellulose surfaces was studied by a number of researchers (Ajdary et al. 2019; Yang et al. 2018; Yan et al. 2013; Ifuku et al. 2007; Jonoobi et al. 2009; Lin et al. 2011). Acetylation is called as the introduction of the acetyl group –COCH3 onto the surface of nanocellulose. Acetic anhydride is the most commonly used

Nanocellulose in Paper and Board Coating

235

reagent for acetylation for getting more hydrophobic surfaces (Beaumont et al. 2020; Zimmermann et al. 2017; Shang et al. 2021). But at the same time different objectives such as enhancing dispersivity (Dong et al. 2017; Achtel and Heinze 2016; Yuan et al. 2006; Zhou et  al. 2015; Mashkour et  al. 2015), increasing mechanical properties (Zhang et al. 2016), improving thermal properties (Yang et al. 2018), and making better barrier properties (Rodionova et al. 2011) are sought. Acetylation reaction of nanocelluloses occurs in the presence of catalysts such as sulphuric and perchloric acids, with gradual addition of acetic acid and acetic anhydride. In the presence of acetic acid with sulphuric acid as a catalyst, acetylation reaction occurs in one of the two routes, namely, homogeneous and heterogeneous routes. In homogeneous route, the hydroxyl groups on the fiber surfaces react with the acetyl groups and trigger the esterification of the three reactive hydroxyl groups (Ashori et al. 2014). Overall, the homogeneous route has some advantages such as completely dissolving the cellulose in the solvent, the better control of degree of substitution, ease in recovery of the dissolved products, and reproducibility (Achtel and Heinze 2016). If the optimal process conditions can be established, the products show homogeneous and more uniform properties (Pakharenko et al. 2017). The use of acetic anhydride and sulfuric acid as catalysts, and pyridine as a solvent diluent in the heterogeneous acetylation of NCs slightly affect the morphological and crystal structures of the samples even after 5 hours at 80 °C (Lin et al. 2011). Acetylation processes include two-step hydrolyses with a strong acid and acetylation (Zhao et  al. 2016b; Ávila Ramírez et  al. 2017). Because of the damage it induces in the crystalline structure and long reaction times, the two-step acetylation process is not cost-effective (Wu et al. 2018; Habibi et al. 2010). On the other hand, one-step acetylation processes have been studied by a number of researchers (Braun and Dorgan 2009; Sobkowicz et al. 2009; Yan et al. 2013; Xu et al. 2020). In the one-step acetylation process of nanocelluloses, the hydrolyses and acetylation processes are carried out in one pot at the same time, called “one pot reaction” (Chin et al. 2018). The resulting acetylated nanomaterial has high crystallinity index and is obtained in a shorter period of time (Xu et al. 2020). The combinations of HCl and acetic acid (Braun and Dorgan 2009), H2SO4 and acetic anhydride (Xu et al. 2020), and phosphoric/polyphosphoric acid and acetic anhydride (Yan et al. 2013) have been used for acetylation of nanocelluloses. Menezes et al. (2009) studied the esterification of NCCs by grafting organic acid chlorides exhibiting different lengths of the aliphatic chains. The reaction was carried out with triethylamine (TEA) as the catalyst and the neutralizing agent for hydrochloric acid (HCl). The crystallinity of the particles was not changed by the modification, but it was noted that the covalently bonded chains were able to crystallize on the cellulose surface when the C18 agent was used. Shang et al. (2021) papered super hydrophobicity with good adsorbing capacity processing with the freeze drying and after esterification. The reaction was environmentally friendly and easy. Beaumont et al. (2020) used acyl imidazole as an acylation agent and achieved wet surface esterification of never-dried (wet), water-swollen

236

A. Tozluoglu et al.

Fig. 15  Acetylation of cellulose fiber with acetic acid and acetic anhydride (Fischer esterification). (Adapted from Xu et al. 2020)

cellulose fibers. With this method cellulose fibers gained higher hydrophobicity in a simple and mild process. Eyholzer et al. (2012) used hexane-alcohol medium and sulfuric acid catalyst for esterifying the nanocellulose. Through the carboxymetylation, it was seen that hexyl monomers replaced the carboxymethyl groups. Curvelo et al. (2009) esterified the nanocellulose particles with organic fatty acid chlorides of different hydrocarbon lengths. They obtained high substitution degrees and high graft densities. Yuan et al. (2006) performedacetylation of the NCs particles with alkenyl succinic anhydride and found an increase in the hydrophobicity of the nanoparticles and dispersibility in the polar solvents with different electric configurations. Berlioz et  al. (2009) reacted the bacterial NCs with hexadecyl chloride vapor and they stated that the efficiency of this reaction is as high as the efficiency of solvent-free esterification. Moreover, they found that the crystal structure of the nanoparticles was not changed significantly. Spinella et al. (2015) mixed lactic acid and nanocellulose with Fischer esterification procedure (see Fig.  15) and they showed a good dispersion of the nanocellulose in a polymer matrix and increased the hydrophobicity of the product. Ajdary et al. (2019) studied the effect of the acetylation of the nanocelluloses on the production of bio-inks. Acetylated nanocellulose produces dimensionally stable monolithic scaffolds that support drying and rewetting, which are needed in applications such as packaging and sterilization. Nanocellulose particles subjected to acetylation treatment reveal a number of preferable features. Accordingly, they reveal high contact angles, hydrophobic surface character, reduced moisture absorption, slightly higher roughness, increased thermal and heat resistances, decreased crystallinity, more porous structure, shorter length and diameter (Cunha et  al. 2014; Ashori et  al. 2014; Abdelmouleh et  al. 2002). Also, recovering and reusing of the ionic liquids are other advantages that the acetylation process offers (Chin et al. 2018). 2.3.2 Etherification As a highly efficient surface modification method, etherification uses epoxylated molecules as the modification agent together with organic solvent-containing heating system (Huang et al. 2019). Several publications have been reported on the use of aqueous–organic solvent mixture as a solvent for etherification (Zaman et  al.

Nanocellulose in Paper and Board Coating

237

Fig. 16 Etherification of NCs with epoxypropyltrimethylammonium chloride (EPTMAC). (Adapted from Habibi 2014)

2012; Ayoub and Bliard 2003; Ayouba et al. 2004). Although the effect of this process is somewhat reduced by polymerization, it still has a high degree of substitution. As is known, the epoxy group reacts with the OH groups on the nanocellulose surface and forms ether bonds. Thus, polymerization occurs on the particle surfaces. This pattern can be enhanced by changing reaction conditions (Zaman et al. 2012). Etherification has been applied for making the nanoparticle surfaces cationic. For example, epoxypropyltrimethylammonium chloride (EPTMAC) was grafted successfully onto the CNC surfaces through etherification (Hasani et al. 2008). This kind of surface cationazition occurs via a nucleophilic addition of the alkali-­ activated cellulose hydroxyl groups to the epoxy portion of EPTMAC. This reaction leads to tixotropic anocellulose suspension (Habibi 2014) (Fig. 16). Although some etherification reactions have known disadvantages such as the use of toxic reactants, yielding more hydrophilic nanoparticles, consumed energy during mechanical treatment after etherification has been over (Olszewska et  al. 2011) and facilitating the dispersion of fillers or dyes (Ho et al. 2011). 2.3.3 Amidation Because most biomolecules have amine groups, surface modification of the NCs via amidation under mild conditions can be regarded as the most effective way. Generally, an amidation reaction is a carbodiimide-mediated reaction and EDAC (C8H17N3) or N-ethyl-N-(3-(dimethylamino)-propyl) carbodiimide hydrochloride are the most widely used carbodiimides for the amidation of the NCs(Thomas et al. 2018). Because coupling reaction is very sensitive to pH it should be conducted at the pH levels of 7–10. Amidation process probably targets the carboxylic groups (–COOH) on the preoxidized nanocellulosic substrates. Naturally there is no – COOH groups on the surface of the NC particles. Therefore, prior to any amidation

238

A. Tozluoglu et al.

modification, oxidation reaction such as TEMPO process should be applied on the NC surfaces (Huang et al. 2019). Some amine derivatives such as 4-amino-TEMPO, benzylamine, hexylamine, dodecylamine and Jeffamine were attached to the surfaces of NCCs or CNFs in carbodiimide-media. N-Ethyl-N-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDAC) is the mostly used carbodiimide derivative that has been reported in the literature for the amidation of nanocellulose without alteration of their native morphological and crystalline attributes (Habibi 2014). Because many biomolecules have amine groups, amidation modification is considered to be a moderate and effective way of modifying nanocellulose surfaces. The amidation reaction occurs both in organic solvents such as dimethyl formamide (DMF) and in aqueous suspensions to conjugate two molecules with carboxyl groups. Since there are generally no carboxyl or amine groups on the surface of a nanocellulose, these groups are applied to the nanocellulose surface before amidation, for example, using TEMPO oxidation. Then, in the aqueous reaction system, the carboxylated nanocellulose reacts with N-hydroxysuccinimide (NHS) with its amide group, which improves the reactivity of the carboxyl groups on the nanocellulose surface. The final step of amidation modification is the mixing of NHS-­ activated carboxylated nanocellulose with amide-containing molecules. The amine groups of the molecules can directly react with the NHS-activated carboxylated nanocellulose and conjugate the molecules to the surface of NC via connection of amide bonds (Cao et al. 2014; Kim et al. 2015a, b). However, if an organic solvent such as DMF is used, instead of aqueous media, the amine-containing molecules can be directly conjugated to the carboxylated surface of nanocellulose (Huang et al. 2019). Palomero et  al. (2015) covalently bonded β-cyclodextrin to amine-modified nanocellulose via amidation and this novel nanocavities were successfully applied to the selective recognition of danofloxacin (DAN), an antibiotic used to treat animal diseases. Le Gars et al. (2020) studied a two-step amidation modification of the NCs. In the first step, the NCC were modified through a TEMPO process and then the preoxidized NCCs were subjected to amidation process with 1-methyl-3-­ phenylpropylamine (1-M-3-PP). In the second step, the amidation process gave rise to the formation of peptide amide bonds and aromatic rings on the surface of the NCC. Amidated NCCs have better dispersion and adhesion in polymers and they

Fig. 17  Silylation of NC surface. (Adapted from Puspasari 2018)

Nanocellulose in Paper and Board Coating

239

can be utilized in food industry and in the production of packaging materials (Raza and Abu-Jdayil 2022). 2.3.4 Silylation Silylation modification is a widely used method for conjugating small molecules to the surfaces of the nanocelluloses. Different silane reagents have been used for modifying both NCCs and CNFs (Gadhave et al. 2021). Silanes have the ability to react with a few free hydroxyl groups present in the cellulose surfaces, as shown in Fig.  17. The modification of the NC surfaces through the silylation method is a simple way to increase the hydrophobicity of the particle surfaces by silane surface functionalization (Thakur et al. 2021). Also, silylation improves the thermal properties and reinforcement characteristics (Zhang et al. 2015). Silane coupling reagents constitute silanol groups on the NC surfaces and caused hydrophobicity of the particle surfaces. Chlorodimethyl isopropylsilane, alkyl-­ dimethylchlorosilanes, alkyl moieties of isopropyl, n-butyl, v octyi and n dodecyl, isocyanatepropyltriethoxysilane (IPTS), and hexamethyldisilazane (HMDS) are used as silylating agents (Jankauskaitė et al. 2020; Andresen et al. 2006; Abdelmouleh et  al. 2002; Goussé et  al. 2002, 2004; Mormann 2003). Hexamethyldisilazane (HMDS) is easy to handle, stable, inexpensive, and is widely used as a silylaton agent for the surface modification of the NCs. In order to enhance the low silylation power and eliminate the problem of long reaction times of the HMDS, some catalysts such as saccarin (Mormann 2003) and formamide (Grunert and Winter 2002) can be used for activating the reagent. The surface modification of the NCs using a silylation process can be achieved via one of the two methods. One is the liquid-phase procedure in which a good immersion of the NCs in the silylation suspension is essential (Andresen et  al. 2006). The second method is the vapor-phase procedure in which the modification is conducted by vaporizing the silane agents at a controlled temperature to get more stable and smooth surfaces (Soliveri et al. 2014; Zhang et al. 2010). Jankauskaitė et al. (2020) observed the differences of vapor-phase and liquid-phase procedures used in the silylation of CNFs with HMDS. Modified CNFs by the vapor phase of HMDS showed smoother surfaces, more hydrophobic behavior, and a greater improvement in the mechanical properties with higher concentrations of Si-containing groups. Besides, in order to enhance the wetting properties of the CNF aerogels, perfluorodecyltrichlorosilane (PFOTS) and octyltrichlorosilane were used for grafting by a chemical vapor deposition method at increased temperature (Cervin et al. 2011; Aulin et al. 2010a, b). Chlorodimethyl isopropyl silane was also used for the silylation of the surface of CNFs and to increase the dispersivity in the polar solvents (Andresen et al. 2006). In another study, Zhang et al. 2010 showed that silylation of the NC surfaces ensures the removal of oil from water. The alkali treatment before silylation is more effective in increasing the silylation efficiency than the original NCs (Abdul Khalil et al. 2014a, b). Silylation of the NC

240

A. Tozluoglu et al.

particles increased the mechanical properties of the composite materials produced with silylated NCs (Pakharenko et al. 2017). Gardner et al. (2008) stated that using methacryloxypropyltrimethoxysilane (MPS) as coupling agent for silylation of NCs, tensile strength and modulus of the composed materials increased by 26% and 17%, respectively. In order to eliminate some disadvantages of the conventional silylation procedure such as complicated solvent exchange procedure and dependence on the organic solvents (Chin et al. 2018), aminosilane compounds such as 3-aminopropyl trimethoxysilane (APTES), 2-aminoethyl 3-aminopropyl trimethoxysilane, and 3-2-(2-aminoethylamino) ethylamino propyl-trimethoxysilane (TAMS) were used for NCCs silylation. Khanjanzadeh et al. (2018) demonstrated the improvement of the hydrophobicity of modified NCC by using APTES and TAMS. You et al. (2019) developed ultra-fast and economically effective sililation by using poly(methylhydrogen)siloxane (PMHS) as a modifier. They found that PMHS chains were covalently grafted onto NCC and that the PMHS modification improved the thermal stability of NCCs. Robles et al. (2018) studied the effect of nine different silane surface modifications on the nanofibrillated cellulose (NFC). They stated that the surface modification increased in direct proportion to silane ration and the aggregation and hydrophobicity of nanofibrils was also increased. Although, during the silylation, degree of substitution between 0.6 and 1 causes an increase in the dispersivity of the NCs on low polarity solvents such as tetrahydrofuran (THF), higher silylation ratio, even in the core of the crystals, results in better dispersion and disintegration but the NC particles lose the original morphologies (Islam et al. 2013; Goussé et al. 2002). Goussé et al. (2004) applied silylation to CNFs produced from parenchymal cell cellulose with isopropyl dimethylchlorosilane. They determined that the morphological properties of the modified NFSs did not change considerably, and that these materials were homogeneously dispersed in nonpolar solvents, resulting in stable non-aggregating suspensions. Andresen and Stenius (2007) silylated the NFSs with chlorodimethyl isopropylsilane (CDMIPS) and found that the modified hydrophobic NFSs with mild degree of substitution (0.6–1) saved their morphological integrity and were able to stabilize water-in-oil emulsions. The silylation process has also been used as an intermediate step in further processes. Aminosilanes were first grafted onto NCCs and used as reactive agents to covalently link fluorescent moieties (Qiang and Pan 2010). In another study, alkene thiol-functionalized silanes were covalently bonded onto NFC-based nanocomposite films and transferred to appropriate sites via the thiol-ene chemistry (Tingaut et al. 2011).

Nanocellulose in Paper and Board Coating

241

Fig. 18  NCCs surface carbanylation. (Adapted from Habibi 2014)

2.3.5 Urethanization The carbanylation method, also known as urethanization and carbamation, refers to the reaction of isocyanate (R–N-C-O) with hydroxyl groups (-OH) on the surfaces of nanocelluloses to form covalent bonds (Thakur et al. 2021; Thomas et al. 2018). The first stated use of isocyanates to modify cellulose nanocrystals was the grafting of polycaprolactone (PCL) to cellulose nanocrystals using tolylene-2,4-­diisocyanate (TDI) (Eyley and Thielemans 2014). Urethanization reaction perfomed on the NCCs or CNFs with N-octadecyl isocyanate (C18H37NCO) at 100–110  °C for 30 minutes in toluene without any catalyst significantly increased the hydrophobicity and dispersivity of NCs (Siqueira et al. 2009; Siqueira et al. 2010a, b). Celebi et al. (2021) studied modification of NCs with n-octadecyl isocyanate and produced composite materials using poly(epsilon-caprolactone) (PCL) by solvent casting method. Surface chemical modification with n-octadecyl isocyanate (C18H37NCO) improved distribution of NCs in PCL matrix and enhanced the rheological and dynamic mechanical properties of the neat PCL. Missoum et  al. (2012a) reported that using n-butyltindilaurate as a catalyst decreases the consumption of isocynate during the reaction time. Thermoplastic polyurethane elastomers were combined with 1,6 hexametylene diisocynate (HDI) modified NCCs at 80 °C with different NCC/HDI mol ratios. Modified NCCs were well dispersed in matrix and obtained materials showed enhanced rigidity and dimensional stability (Rueda et al. 2011). Stenstad et al. (2008) used hexamethylene diisocyanate (HDI) to modify the surface characteristics of NFC. Water from the NFC suspension was replaced by acetone and then by Tetrahydrofuran (THF). At the end of the reaction, which lasted for 2 hours at 50 °C, the strength properties and solubility of the NFC were not changed significantly. Habibi (2014) produced NCCs coated with a molecular polysylsesquioxane layer via coupling of NCCs with 3-isocyanatepropyltriethoxysilane (IPTS) in DMF followed by cross-linking of silane groups with the addition of water (see Fig. 18). Recently, Biyani et  al. (2013) reported the isocyanate-mediated coupling to NCCs with H-bonded ureidopyrimidione (C5H6N4O2), and Navarro and Bergström (2014) modified CNFs with Butyl 4-(Boc-aminomethyl) phenyl isothiocyanate using DMSO as solvent.

242

A. Tozluoglu et al.

2.3.6 Sulfonation Sulfonation means making anionic charge on the nanocellulose surfaces. The nanocrystalline cellulose (NCC) is treated with concentrated H2SO4 (sulphuric acid) and in this process sulfate half-esters are formed from the hydroxyl groups (-OH) of the nanoparticle surfaces that lead to hydrolysis of sulfuric acid. While the ionic strength increases, the pitch of the resulting chiral neumatic structure decreases during the process (Thakur et al. 2021; Dong et al. 1996). At the end of the sulfonation, NCC colloidal suspension is stable (Thomas et al. 2018). Formed negative electrostatic charge on surface of the nanocellulose facilitates the dispersion of the particles in water. Decreasing the sulphate group increases the thermal stability of NCCs (Thomas et al. 2018). Thermal stability of the H2SO4 isolated NCCs can be increased by applying neutralization with NaOH (Mu and Gray 2014). For obtaining sulfonated CNFs with width between 10 and 60  nm, Liimatainen et  al. (2012) added NaIO4 (periodate) and NaHSO3 (bisulfite) to nanofibrillated hardwood pulp. For the precise control of the amount of sulfate groups, it should be noted that the degree of esterification depends on various factors such as hydrolysis time, temperature, and acid concentration (Abitbol et al. 2013). In order to keep the formation of ester groups under control, it has been proposed to post-treat NCCs produced by hydrochloric acid hydrolysis with sulfuric acid. (Araki et al. 1999). The NCCs produced by hydrochloric acid hydrolysis and subsequently treated with sulfuric acid have the same particle dimensions as those produced directly by sulfuric acid hydrolyses. Using ultrasonication with the presence of sulfuric acid and hydrochloric acid resulted in the production of NCCs with spherical shape instead of rod-like NCCs (Daud and Lee 2017; Wang et al. 2008). The main disadvantage of the sulfonation of nanocelluloses is the poor thermal stability which limits their use in, for example, nanocomposite production (Camarero Espinosa et al. 2013). Because of the less amount of sulfate group on the particle surfaces, spherical shaped particles have better thermal properties than the NCCs produced from sulfuric acid hydrolyses (Wang et  al. 2007b). On the other hand, there are several areas where high thermal stability of nanomaterials is not desired such as purification agent for removing the heavy metals (Suopajärvi et al. 2015), stabilization of pH (Naderi et al. 2017), and thickening agent (Sirviö et al. 2019). Lin and Dufresne (2014) explored the sulfonation method (chlorosulfonic acid) to introduce sulfate groups on the surface of NCCs and studied the surface chemistry, physical properties, and particle morphologies. Liimatainen et al. (2013b) used a sulfonation process consisting of oxidation and sulfonation steps on the surface of NCCs. Although oxidation and sulfonation processes occur sequentially in adjacent hydroxyl groups at positions 2 and 3 of the glucose unit, CNFs that trigger the opening of the glucopyranose ring preserved their natural crystal structures even at high sulfate ratios thanks to this modification (Liimatainen et al. 2013a, b). As easy-to-handle and environmentally friendly chemical, the reactive deep eutectic solvent (DES) based on sulfamic acid and urea was found to be an efficient sulfonation agent for cellulose fibers. Owing to their high viscosity, even at low concentrations, sulfonated NCCs exhibit the potential to be used as a rheology

Nanocellulose in Paper and Board Coating

243

modifier, for example, in hygienic and food applications or as reinforcing additives (Sirviö et al. 2019). 2.3.7 TEMPO-Oxidation TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) is a water soluble, commercially available, and stable nitroxyl radical. With catalytic oxidation using TEMPO, an efficient and selective conversion of alcoholic hydroxyl groups to aldehydes, ketones, and carboxyl groups under mild conditions is possible. (Isogai et al. 2011). Because the conversion of C6-OH groups on the surfaces of the NCs to sodium carboxylate can easily be achieved via TEMPO oxidation, it has been used for carboxylation of NCs (de Nooy et al. 1996). The use of TEMPO-oxidation at mild reaction conditions (i.e., at room temperature and pH:7–10 with the presence of NaClO/NaBr) formed C6-carboxylates on the nanocellulose surfaces (Isogai et al. 2018; Hirota et al. 2010). On the other hand, prolonged reaction time and high TEMPO concentration can break down the chemical bonds between glucosidic units and, thus, it can lead to nanoparticles with nonuniform chemical structure and surface (Perez et al. 2003). The most commonly used TEMPO oxidation system is TEMPO/NaClO/NaBr at alkaline pH for high oxidation yield. An alternative system is the sodium chlorite catalyzed TEMPO oxidation system: TEMPO/NaClO/NaClO2 in a buffer at pH 4.8–6.8 (Zhao et al. 1999). The latter system, although susceptible to acid hydrolyses, yielded relatively stable cellulose under alkaline conditions (Isogai et  al. 2011) (see Fig. 19).

Fig. 19  Schematic ilustration of the TEMPO oxidation of cellulose primary alcohol groups by: TEMPO/NaBr/NaClO in water at basic pH and TEMPO/NaClO/NaClO2 in water at neutral or slightly acidic pH. (Adapted from Isogai et al. 2011)

244

A. Tozluoglu et al.

In general, TEMPO oxidation is used to facilitate the isolation of the fibers before mechanical treatment. Highly crystalline tempo-oxidized nanoparticles can be easily blended and mechanically sheared (Habibi 2014). Araki et al. (2001) studied the TEMPO oxidation of NCCs produced with HCl hydrolyses. They showed that the TEMPO-oxidized NCCs preserved their original morphologies and when dispersed in water they formed a homogeneous suspension. Carboxyl groups formed on the NCC surfaces after oxidation are negatively charged and provide the cotton linter NCCs with thermal stabilization. During TEMPO oxidation, crystal dimensions of the NCCs were decreased and dispersion properties of the suspension were increased (Montanari et  al. 2011). Nanoparticle dimensions and charge density directly affect the rheological properties of the NC suspensions (Saito et al. 2007). Elastic modulus of the NC suspensions by TEMPO-­mediated oxidation of pulp is higher. For this reason, some researchers ascribe this to the higher charge density of the fiber surfaces (Mavelil-Sam et  al. 2017). PVA films reinforced by TEMPO-oxidized NCs showed higher strength and elastic modulus than unfilled polymer (Deepa et al. 2013). TEMPO oxidation is usually applied as a pretreatment stage for the production of nanofibrillated celluloses (CNFs). There are two main advantages of using TEMPO-oxidized NCs in the industrial applications. The main characteristics of the original fibrous material are preserved on the particles even though great number of hydrophilic sodium carboxylate groups are formed after TEMPO oxidization of celluloses (Saito et  al. 2007). Another advantage is that the inexpensive pulps such as bleached kraft and sulphite pulps can be effectively used in the production of TEMPO-oxidized NCs. On the other hand, the major drawbacks of TEMPO oxidation include high cost, difficulty in separation of nanofibers and contaminants, and relatively low degradation temperatures of the TEMPO-oxidized NCs (Isogai et  al. 2011; Pakherenco et al. 2017). Another oxidation agent for the NCs is ammonium persulfate (APS). Compared to TEMPO ozidation method, APS oxidation produces a low surface charge (Culsum et al. 2021). The surface charge of NCs is generated during the isolation or surface modification process (Marwanto et al. 2021). Because of the higher oxidative properties of the APS, dimensions of the NCs are shorter and thinner than those obtained via traditional oxidation procedures (Leung et al. 2011). 2.3.8 Carboxymethylation Carboxymethylation is the substitution reaction of hydroxyl groups (-OH), located on the NC surfaces, with carboxymethyl groups. Carboxymethylation has long been applied to the cellulose. Recently, this modification method has also been used in the production of NCs. Ryu et al. (2019) studied the production of carboxylated NFC-polyacrylamide (PAM) films. They obtained eco-friendly functional materials with high thermal and mechanical performance in emerging application areas of NCs such as papermaking, coating, gas barrier, food packaging, and optical films.

Nanocellulose in Paper and Board Coating

245

Siró et  al. (2011) produced solvent cast films from carboxylated CNFs. They stated that the transparency increases with increasing homogenizatition. Past research efforts have shown that the carbxymethilated NCs have stronger fibers, better mechanical and barrier properties, enhanced dispersibility in water, improved network structure of the NFC, and higher water retention value (Yi et al. 2020; Naderi et al. 2016). Also, Oun and Rhim (2017) produced NC-based nanofilms using amonium persulphate-oxydized NCCs obtained from cotton linters and NFC-based NCCs. Cotton linter-based NCCs showed a more uniform particle size distribution, higher crystallinity, transparency, thermal stability, and better mechanical strength compared with the NCF-based NCCs. Major drawbacks of carboxymethylation procedure include the use of toxic chemicals in the pretreatment stage, complex and slow reaction steps, and low transparency and poor mechanical properties because of the intensive fiber fragments in NFC (Raza and Abu-Jdayil 2022; Yi et al. 2020). 2.3.9 Phosphorylation Surface modification via phosphorylation is a reaction between the phosphate and nitrogen containing organic substances. Modification of NC surface via phosphorylation is a reaction with phosphate and nitrogen containing organic substances. The widely used substance for phosphorylation is urea (CH4N2O) in its high oxidation media. Phosphoric acid (H3PO4) is used during the phosphorylation stage of NCs to gain heat resistance and flame retardancy. Different phosphor compounds such as

Fig. 20  Cellulose phosphorylation using POCl3 and P3N3Cl6 reagents. (Adapted from Blilid et al. 2019)

246

A. Tozluoglu et al.

phosphorous acid (H3PO4) (Suflet et  al. 2006; Inagaki et  al. 1976) and diamoniumphosphate ((NH4)2HPO4) (Ghanadpour et al. 2015), and different ionic forms of phosphoric groups (H2PO4−, HPO4−2, PO4−3) (Messa et al. 2021) are also used for NC surface modification processes. After modification, the nanocellulose surfaces become negatively charged (Naderi et  al. 2016) and show enhanced dispersion properties. Also, nanopaper samples produced from phosphorylated NFC showed self-extinguishing properties because of the presence of the phosphate groups in the NFC (Ghanadpour et al. 2015). Phosphorylated microcrystalline cellulose (MCC) and nanocrystalline cellulose (NCC) have been prepared and used as reinforcing fillers to produce transparent and flexible cellulose-filled chitosan nanostructured films by Blilid et al. (2020). As a result, phosphorylated cellulose fillers (P-CNC and P-MCC) also showed interesting antibacterial and intercellular catalase activities. Blilid et al. (2019) also functionalized MCC and CNC using two phosphorus derivatives (phosphoryl chloride-POCl3 and hexachlorocyclotriphosphazene-P3N3Cl6), under acid-free, urea-free, and corrosive-­free gentle experimental conditions. The presence of phosphorus fragments enabled the anchoring of ultra-stable metal oxide clusters on the NC surface through metal-­phosphonate (P-O-Ti) bridges (see Fig. 20). Liu et al. (2015) studied enzymatic phosphorylation of the NCs and reported that introduction of phosphate groups onto nanocelluloses significantly improved the metal sorption velocity and that the phosphorylated nanocelluloses are highly efficient materials for scavenging multiple metal ions from industrial wastes. Phosphorylation method is favored for a number of reasons: to obtain improved fire

Fig. 21  Three approach for grafting of nanocellulose. (Adapted from Thomas et al. 2018)

Nanocellulose in Paper and Board Coating

247

retardancy, higher mechanical strength, and enhanced biological properties; better recovery of the nontoxic reagent of NC dispersions and scavenging metal ions. 2.3.10 Grafting of Nanocellulose Grafting of NCs is applied for achieving improved physical and mechanical properties (Roy et al. 2009; Lizundia et al. 2016) such as surface hydrophilicity/hydrophobicity, absorbency, elasticity, thermal resistance, and self-cleaning surfaces (Thomas et al. 2018). Due to their enhanced mechanical and biocompatible properties, the grafted NC materials can be used for producing some surgical repair applications (Hansson et al. 2013; Tzanov et al. 2002). Grafting of polymers onto NC surfaces can be realized via three approaches: grafting onto, grafting from, and grafting through (Thakur et al. 2020) (Fig. 21). 2.3.10.1  Grafting Onto In the “grafting onto” approach, a previously synthesized polymer such as polypropylene ((C3H6)n), polystyrene ((C8H8)n), poly(lactic acid) ((C3H4O2)n), poly(caprolactone)((CH10O2)n) or peptite chains carrying reactive end groups attach to the modified -OH groups on the NC surfaces by using coupling agents. The steric hindrance may prevent optimal bonding from occurring during the grafting process because the polymer chains must be able to pass through the readily bonded layers to reach the reactive sites present on the surface. Therefore, a reduced surface grafting density is usually achieved using the “grafting on” modification method (Zhu and Lin 2019). Maleated polypropylene (PPgMA) was used by Ljungberg et  al. (2005) for grafting onto the surface of tunicate CNFs. Obtained CNFs showed compatibility and high adhesion when dispersed in a tactic polypropylene. Wang and Sain (2007) treated the CNFs using five different chemicals including ethylene acrylic acid, styrene maleic anhydride, guanidine hydrochloride, Kelcoloids® HVF, LVF stabilizers (propylene glycol alginate), and then prepared bio-nanocomposites using PLA and PHB as matrices. Grafted nanoparticles were dispersed only partially and mechanical properties were not found to be satisfying, as estimated before. Because of the hydrophobic character and having simple structure, poly(ethylene glycol) (PEG) and polyoxyethylene (PEO) are generally used as agents for grafting onto the NC surfaces. Araki et al. (2001) performed amine-terminated PEG grafting of TEMPO-NCC suspensions using an aqueous method of carbodiimide-catalyzed amidation at room temperature. Redispersibility properties of the modified NCC particles in water and chloroform were enhanced significantly. Labet et al. (2007) performed the grafting of polycaprolactones (PCL) of different molecular weights onto the surface of NKSs in a three-step process using isocyanate. The resulting graft density was found to be high enough that grafted PCL chains could crystallize on NCC surfaces. With continuous addition of coupling

248

A. Tozluoglu et al.

agent and catalyst for 7 days at 80 °C, grafting density can be increased and also for better dispersion, high amount of toluene should be used. Similarly, water-based polyurethane (WPU) polymers were grafted onto NKS surfaces by catalyzing with isocyanate in DMF medium. These grafted polymers formed a crystalline structure on the surface of NCCs and, thus, crystallization of a continuous phase-forming matrix was achieved (Cao et al. 2009). Pei et al. (2011) prepared polyurethane – NCC nanocomposites to increase the mechanical properties of the polyurethane. 2.3.10.2  Grafting From “Grafting from” approach involves direct polymerization of monomers on the NC surfaces. The polymer chains are formed by in situ surface-initiated polymerization from the immobilized initiators on the NC surfaces. Polymer densities and polydispersities are greater than the grafting onto processes, but it is difficult to characterize the resulting polymers (Habibi et  al. 2010; Habibi 2014; Daud and Lee 2017). Moreover, the “grafting trough” route ensures functionalization of the NCs by using vinyl bearing polymerizable monomers and, then, in order to start the polymerization reaction, modified NC is mixed with a co-monomer (Thakur et al. 2020; Kumar et al. 2019; Thomas et al. 2018). “Grafting from” involving ring opening polimerization is known as the mostly used method. In addition, the grafting onto procedures runs with many approaches

Fig. 22  Ring opening polymerization of PCL, PLA, and PCL-b-PLA initiated from NCC surfaces. (Adapted from Habibi 2014)

Nanocellulose in Paper and Board Coating

249

such as ring opening polymerization (ROP), free radical polimerization (FRP), and living free radical polymerization (LFRP) (Kedzior et al. 2018). 2.3.10.2.1  Ring-Opening Polymerization (ROP) The ring-opening polymerization (ROP) method is used to graft and polymerize cyclic monomers, especially lactones. Habibi and Vignon (2008) applied ROP as the first grafting from procedure. Goffin et al. (2011) grafted polycaprolactone onto the surface of NCFs via ring-opening polymerization (ROP) using stannous octoate (Sn(Oct)2) as a polymerization agent at 95 °C in toluene media. After grafting modification, the original crystalline structure and morphologies were protected but the length of grafting chain in the modified products was short due to the crystallization of PLA on the surface of nanocellulose (Goffin et al. 2011). As can be seen from Fig. 22, in another notable study, Goffin et al. (2012) used Sn(Oct)2-catalyzed ring-­ opening polymerization to graft PCL and then PLA onto the surfaces of NCCs. Despite the long reaction time under metal-catalyzed ring-opening polymerization conditions, the morphologies and crystal structures of NCCs were preserved. These NCCs grafted with PCL-b-PLA copolymer exhibited different crystallization behavior and dispersion when combined with a mixture of PCL and PLA.  For obtaining a high molecular weight in the grafted PLA chains, Braun et al. (2012) suggested the use of partially acetylated NCCs followed by the Fischer esterification pathway. With this method, high-molecular-weight chains were covalently attached to the NCC surface. Significant enhancement of the mechanical properties was obtained. To enhance the grafting effect, Chen et al. (2009), Lin et al. (2009) carried out the grafting reactions under microwave irradiation without using any solvent. PCL grafted long chains were entangled during thermoforming, thereby producing molded sheets with good mechanical properties. In order to decrease the use of metal-based catalysts, Labet and Thielemans (2012) used natural citric acid under conditions proper for the ROP. This kind of natural and harmless chemicals have been approved for producing environmentally friendly materials. Lönnberg et al. (2008, 2011) studied the wood extracted NFC modification with different poly- caprolactone (PCL) polymers in toluene solvent with Sn(Oct)2 catalyst. They found an impact on the mechanical properties with respect to the PCL graft lengths, and the strongest biocomposites were obtained after reinforcement with CMF (cellulose microfibril) grafted with the longest PCL graft length. 2.3.10.2.2  Free Radical Polymerization (FRP) Free radical polymerization route does not require a pre-step to attach surface initiators for grafting from NCCs. In order for polymer to grow from the NCC surfaces, water soluble radical initiators are used for reacting with the cellulose backbone or surface –OH groups. Free radical polymer grafting from NCCs has been successfully carried out with ceric ammonium nitrate (CAN), potassium persulfate (KPS) and ammonium persulfate (APS), and a range of water-soluble monomers as

250

A. Tozluoglu et al.

initiators (Kedzior et al. 2018). This approach yields a stable, green NCC suspension having enhanced compatibility with NC polymers and increased colloidal stability. Kan et al. (2013) used CAN to graft from NCCs with pH responsive hydrophilic poly(4-vinylpyridine) (P4VP). It is demonstrated that the grafted nanomaterial has a good potential for being used as a reversible flocculant. Tang et al. (2016) studied poly (oligoethylene glycol) methacrylate (POEGMA) for grafting from CNCs by using CAN. Furthermore, CAN has been used with poly(methacrylic acid) (PMAA) to graft NCC surfaces for getting hydrophobic NCCs (Kedzior et  al. 2016), poly(glycidyl methacrylate) for improving NCC compatibility in nanomaterials (Pracella et al. 2014), and poly(acrylamide) for obtaining hydrogels (Li et al. 2018). In order to prevent formation of locally aggregated zones during the grafting and polymerization processes with water soluble salts, sonication has been recommended for better energy efficiency and mass transfer in the suspension. (Kan et al. 2013; Kedzior et al. 2016; Tang et al. 2016). Some hydrophilic polymers such as poly(acrylamide) (Zhou et al. 2011; Yang et al. 2013b), poly(acrylic acid) (Wu et al. 2017), poly(methacrylic acid-co-ethylene sulfonic acid) (Anirudhan et al. 2013), the hydrogen bonding moiety 2-ureido-­4[1H]pyrimidone (Liu et al. 2017), and recently hydrophobic poly(styrene) (PS) (EspinoPérez et al. 2016) were used with KPS for grafting from NCCs. APS was used with grafted poly [2- (dimethylamino)ethyl methacrylate] (PDMAEMA) by Tang et  al. (2014) from NCCs. The modified NCC solutions showed pH- and thermo-responsive characteristics as a Pickering emulsion. Also APS with poly(N-isopropylacrylamide) (PNIPAM) was used by Zubik et al. (2017) for getting thermoresponsive hydrogels. Although the free radical graft polymerization method generally causes high polydispersity, it is very difficult to control the length of the grafted polymers and grafting density. Another disadvantage of the free radical polymer grafting method is production of “side” homopolymer chains during grafting reaction other than the grafting chains on NCCs. Therefore, it has some favorable properties such as working in water media under mild conditions and the yield of polymer-grafted NCCs is low (Kedzior et al. 2018). 2.3.10.2.3  Living Free Radical Polymerization (LFRP) Because of the relative tolerance for moisture and some purities, living free radical polymerization (LFRP) method has been a popular approach. In order to establish optimum conditions in a living free radical polymerization, the following requirements need to be satisfied: For optimum living free radical polymerization, the following requirements are seen: (i) the concentration of radicals is constant and low; (ii) the chain transfer and chain termination reactions are negligible due to the low concentration of radicals; (iii) the initiation of radicals is much faster than the propagation step; (iv) the molecular weight of polymers increases proportionally with the monomer (Zhang et al. 2021). Many kinds of LFRP have been studied thus far. These include atom transfer radical polymerization (ATRP) (Matyjaszewski 2012), reversible addition-fragmentation chain transfer (RAFT) polymerization (Moad

Nanocellulose in Paper and Board Coating

251

2017), and nitroxide -mediated polymerization (NMP) (Zhang and Maric 2011). The term of LFRP was replaced with reversible deactivation of radical polymerization (RDRP) by the International Union of Pure and Applied Chemistry (IUPAC) (Zhang et  al. 2021). The controlled radical polymerization (CRP) is yet another term used by Kedzior et al. (2018). Atom transfer radical polymerization (ATRP), first developed by Wang and Matyjaszewski (1995), is the most widely used living free radical polimerization method. ATRP has been described as the reaction of surface hydroxyl groups with 2-bromoisobutyryl bromide, used to initiate the ATRP polymerization of methyl acrylate (Carlmark and Malmström 2002). In the other simple description, ATRP grafting of NC is a free radical polymerization process applied to styrenes (C8H8), methyl-acrylates (C4H6O2), (meth)acrylamides (C4H7NO), and acrylonitriles (C3H3N) (Thomas et al. 2018; Hansson et al. 2009). Obtained cellulosic material gains more hydrophobic character and the contact angle is around 133° (Thomas et al. 2018). The ATRP process can also be catalyzed through a redox mechanism via transition of metal complexes (see URL 1). The grafted NCC showed improved dispersivity in some solvents such as dioxane, tetrahydrofuran, dimethylformamide (DMF), ethanol, and water while retaining the natural rod-like structures of the ungrafted NCC.  To vary the dispersion characteristics of the grafted NCCs, the lower critical solution temperature (LCST) can be adjusted between 34 °C and 66 °C by changing the feed ratio of different comonomers (Chin et al. 2018). The polymer chains grow by the addition of the monomers to the radicals like a conventional radical polymerization propagation process (Zhang et al. 2021). Some successfully polymerized monomers with the ATRP include styrene, (meth) acrylates, (meth) acrylamides, dienes, acrylonitrile, and other monomers that can stabilize the propagating radicals (Fantin et al. 2016). The grafting reaction of polyolefin chains on NCCs with the ATRP method takes place in two steps. In the first step, an initiator is fixed to the nanoparticles and a macromolecular initiator (commonly used NCC-Br) is obtained for the formation of the initial sites of living radical polymerization (LRP). In the second step, the reaction of the modified nanoparticles with monomers (C = C alkene molecules) occurs for polymerization. In recent years, surface-initiated ATRP (SI-ATRP) was developed for grafting of polymer brushes from the NC surfaces in a controlled manner and with higher grafting density. High amount of grafted nanomaterials with well-defined structure suitable for different applications can be obtained with SI-ATRP method (Zhang et al. 2018; Yan et al. 2016). The first step is to introduce brominated ATRP initiating sites on the surface of the nanoparticles (Br-NCC). The amount of ATRP initiating sites on brominated NCs directly affect the maximum polymer grafting density (Zhang et al. 2019). The amount of the –OH groups directly affects the surface modification by covalent bonding (Zhang et  al. 2021; Brand et  al. 2017). Therefore, reacting chemicals with -OH groups on the surface can be used for the modification of the NCs.

252

A. Tozluoglu et al.

Prior to the grafting by SI-ATRP through esterification of the surface hydroxyl groups -OH on the NC, the method of α-bromoisobutyryl bromide (BIBB) is used in general. The BIBB method works for bonding the Br on NC surface prior to SI-ATRP process (Zhang et al. 2021; Morandi and Thielemans 2012; Yu et al. 2014; Hansson et al. 2015). Although different solvents such as water, dimethylformamide (DMF), or dimethyl sulfoxide (DMSO) can be used for the esterification of NCCs with BIBB, the DMF is the most frequently used solvent. But the use of excess amount of DMF increases the cost and makes the process less environmentally friendly (Zhang et al. 2021). Xu et al. (2008) and Yi et al. (2008) used Br-NCC (poly)styrene (PSt) for grafting NCC surfaces by SI-ATRP method and NCC surfaces were esterified with BIBB in tetrahydrofuran (THF) in the presence of 4-dimethylaminopyridine (DMAP) and triethylamine (TEA). Different polymers have been studied for grafting NCs. These include polystyrene (PS) (Yi et  al. 2008), poly [2-(N, N-dimethyl amino) ethylmethacrylate] (PDMAEMA) (Yi et al. 2009)], poly{6-[4-(4-methoxyphenylazo) phenoxy] hexyl methacrylate} (PMMAZO) (Xu et al. 2008), poly(4-vinylpyridine) (P4VP) (Zhang et  al. 2018), poly (n-butyl acrylate), poly(2-(dimethyl amino) ethylmethacrylate (Morits et al. 2017), polymethylmethacrylate (PMMA) (Meng et al. 2009; Yin et al. 2016), poly(N-isopropylacrylamide) (PNIPAM) (Zoppe et al. 2010; Wu et al. 2016), N,N,N′,N″,N″-pentamethyl-diethylenetriamine (PMDETA) (Hansson et al. 2015), N,N,N′,N′-tetramethyl-O-(1H-benzotriazol-1-yl)uronium hexafluorophosphate (HBTU) (Werner et  al. 2019), poly(N-isopropylacrylamide) (PNIPAM) (Risteen et al. 2018), poly(butyl acrylate) (PBA) (Li et al. 2011), and butyl acrylate (BA) (Xiao et al. 2011). Zoppe et  al. (2010) reported that NCCs were grafted with thermosensitive poly(N-isopropylacrylamide) using the SI-SET-LRP (surface-initiated single electron transfer-living radical polymerization) method under different conditions at room temperature. In this method, Cu(I) was rapidly converted to Cu(0) and Cu(II) by a simple catalyst removal process. It was determined that the molecular mass of the branches in the polymer increased as the initiating charge increased. Although it can be controlled and has higher grafting density, some drawbacks related to the operational difficulties (e.g., freezing-pumping-melting or vacuum-nitrogen cycle issues) and hard conditions under anaerobic circumstances make this process less favorable (Huang et al. 2019). Reversible addition fragmentation chain transfer (RAFT) route of grafting is one of the most versatile and convenient living free radical polymerization methods to obtain soluble cellulose (Roy et al. 2007; Thakur et al. 2021). The most commonly used RAFT agents are dithioesters, dithiocarbamates, trithiocarbonates, and xanthates (Braunecker and Matyjaszewski 2007). A macro chain transfer agent was created by attaching dithioesters to the primary alcohol(-CH2OH) at the C6 position of the cellulose backbone, followed by polymerization of either ethyl acrylate (C5H8O2) or N-isopropylacrylamide (NIPAM) (Thomas et  al. 2018). Poly(2(dimethylamino) ethyl methacrylate) or p-DMAEMA (C8H15NO2) is modified with grafting on the cellulosic surface using the RAFT method (Roy et al. 2008; Roy

Nanocellulose in Paper and Board Coating

253

Fig. 23  Vinyl acetate grafting from chain transfer agent (CTA)-modified NCCs with RAFT approach (AIBN: 2,2′-azobis(2-methylpropionitrile as initiator, ETOAc: ethyl acetate as free chain transfer agent). (Adapted from Kedzior et al. 2018)

et al. 2007; Thomas et al. 2018). RAFT approach has also been used to obtain antimicrobial NCC surfaces. Alkyl bromides with 8, 12, or 16 carbon atoms were used to quaternize poly(2-(dimethylamino) ethyl methacrylate) chains on the cellulose surface (Roy et al. 2008). Longer alkyl chains on the surface of the NCs amounts to more resistance to the water and the less interaction with the bacteria in the solution (Thomas et al. 2018). Boujemaoui et al. (2016) used two-stage RAFT process for improving mechanical properties of the NC material. In the first stage, the NCCs were treated with chain transfer agent and in the second stage, the vinyl acetate was polymerized from CTE-NCCs for obtaining polymer-grafted NCCs (see Fig. 23). Nitroxide-mediated polymerization (NMP)is a polymerization process based on the reversible activation/deactivation of growing polymer chains by a nitroxide radical (Barbey et al. 2009). As with the ATRP process, this approach allows for the synthesis of well-defined polymeric structures derived from monomers such as styrene, acrylates, and methacrylates (Roeder et al. 2016). The NMP process is known to be one of the simplest radical polymerization techniques as it does not involve reversible redox processes or chain transfer reactions. Moreover, the NMP process does not require a post-treatment for the removal of transition metals, or color- or odor-causing endgroups. On the other hand, the major disadvantages of the NMP process include low polymerization rates, requirement for higher temperatures, and a rather limited range of monomers suitable for the process (Roeder et al. 2016). NMP is also used for surface-initiated polymerizations and for grafting from NC surfaces. While applying the NMP process via grafting from approach, a substrate

254

A. Tozluoglu et al.

Fig. 24  Mechanism of NMP. (Adapted from Braunecker and Matyjaszewski 2007)

is functionalized with a nitroxide moiety, producing an alkoxyamine that is able to initiate and mediate the polymerization from the surface of the substrate (Roeder et al. 2016). General mechanism of NMP process is shown in Fig. 24. In one of the few studies that are concerned about grafting from NCC using NMP method, Roeder et al. (2016) produced CNC-g-PMMA and CNC-g-PMA in the first stage treating with 4-(chloromethyl) styrene in DMSO, followed by N-(2-­ m e t h y l p r o p y l ) - N - ( 1 - d i e t h y l p h o s p h o n o - 2 , 2 - i m e t h y l p r o p y l ) - O - ( 2 -­ carboxylprop-­2-yl) hydroxylamine in t-butanol, and then polymerized with methyl methacrylate (MMA) or methacrylate (MA). Polymer-grafted NC showed good solubility property in organic solutions. Also, using the same procedure Garcia-­ Valdez et  al. (2017) applied CO2-responsive polymers for grafting from NCCs. Obtained polymer grafted NC has attained reversible CO2-responsible properties in water.

2.4 Effect of Nanocellulose in Paper and Board Coatings 2.4.1 Properties of Nanocellulose Coated Paper and Boards 2.4.1.1  Physical Properties Thickness, density, bulk, air permeability, and smoothness are the physical properties of the paper. 2.4.1.1.1 Thickness The thickness of the paper is the mm value of the distance between the top and bottom surfaces of a single paper sheet. The viscosity and depth of penetration of the coating materials used in the size press and rod coating applications affect the thickness of paper (Boissard 2017). The use of CNF/CNC/CMF/CMC as coating material in paper generally increases the thickness. As the weight of nanocellulose used as a coating material increases, the thickness of the paper increases. Beneventi et al. (2014) showed that when different types of paper substrates (abaca pulp, abaca pulp and wood pulp mixture, softwood kraft pulp) were coated with microfibrillated cellulose (CMF) at different amounts (mass per unit area), the thickness of the paper substrates increased with increasing amount of CMF. The fact that the coating has one or more layers also affects the thickness of the paper. According to Afra et al. (2016), when they

Nanocellulose in Paper and Board Coating

255

examined the physical properties of the paper covered with 1.5% and 3% CNF as single and double layers, they found that the paper coated with 1.5% by weight of double-layer CNF was thicker than the paper coated with 3% by weight of single-­ layer CNF. In a similar study, the thickness increased by 25% by applying CMF coating on cardboard 10 times (Lavoine et al. 2014a). Pego et al. (2020) added 10% CNF as an additive and coating to the papers produced from different fiber sources including Eucalyptus, Sisal, and Pine. The highest values in thickness measurements were determined in the coating method. This result is attributed to the fact that there is surface accumulation and no loss of nanocellulose in the coating method compared to the additive method during layer formation. There are also studies in which the thickness of paper either decreased or not affected by the use of CNF/CNC/CMF/CMC as a coating material on paper. Fidan et al. (2021) observed that the thickness decreased when 0.5% CNF and 4% starch were added to the paper in a size press process. They also found that when 1% CNF was used, the thickness did not change appreciably. This result was attributed to the proportionally higher proportion of starch at low CNF ratios (0.5% and 1%). During the size press application on the paper surface, starch suspensions penetrate into the surface more easily than the CNFs. It was determined that the thickness increased when the CNF ratio was more than 1% (Fidan et al. 2021). 2.4.1.1.2 Density Density of paper indicates the amount of mass per unit volume. Density, which affects the strength properties, is one of the most important physical properties of paper (Hollertz et al. 2017). The use of CNF/CNC/CMF/CMC as coating material in paper generally increases the density. Tarrés et al. (2016) used the CNF produced by TEMPO oxidation as a coating material on paper and determined that the density of paper increased with increasing CNF concentration. In a similar study, the increase in the ratio of CMF used as a coating material in paper increased the density (Beneventi et  al. 2014). Tarrés et  al. (2022) coated the paper surface with endoglucanase-­hydrolyzed micro-/nanofibers (CMNF) at different loadings (wt%), based on dry pulp weight. To facilitate the adhesion, they also utilized cationic starch and silica at 0.8 wt% and 0.5 wt%, respectively. It was determined that the density of paper slightly increased with increasing CMNF concentration and coating number (Tarrés et al. 2022). On the other hand, a number of studies have reported that the use of CNF/CNC/ CMF/CMC as a coating material either decreased or did not change the density of paper specimens (Fidan et al. 2021; Pego et al. 2020). Fidan et al. (2021) studied the effect of CNFs as a reinforcing agent on paper and determined that the paper samples processed via size pressing experience reduction in density. The reduction in density was attributed to the precipitation of the suspension on the surface as a layer and thus to the increase in CNF concentration on the surface. In another study, when 10% CNF was added as additive and coating to papers prepared from different fiber sources, it was determined that the apparent density values decreased in the coating

256

A. Tozluoglu et al.

method compared to the additive method (Pego et al. 2020). The result was attributed to the increase in thickness which occurs during the coating process. 2.4.1.1.3 Bulk The bulk is a property of paper and defined as the the volume of paper per unit weight. The use of CNF/CNC/CMF/CMC as a coating material in paper generally increases the bulk of paper. Lavoine et al. (2014a) applied CMF coating on the cardboard samples and determined that the bulk value of the samples coated with 10 layers of CMF coating increased by as much as 20% compared to the bulk of uncoated control sample. Pego et  al. (2020) added 10% CNF as an additive and coating to the papers produced from different fiber sources including Eucalyptus, Sisal, and Pine and determined that the increase in volume is more significant in the coating method compared to that in the additive method. 2.4.1.1.4  Air Permeability Air permeability is defined as the amount of air in cm3 passing through a unit area in unit time. Air permeability gives an information about the porosity of the paper. The use of CNF/CNC/CMF/CMC as coating material generally decreases the air permeability of the coated paper. Hassan et al. (2016) studied the effect of CMF and chitosan nanoparticles as coating materials on paper and observed that the air permeability of the coated specimens dropped by as much as 44%, as revealed by the specimen containing 5% chitosan nanoparticle. Aulin et al. (2010b) found that as the weight of CMF coating is increased the air permeability of coated pulps decreased in both oil-bleached and unbleached specimens. In another study, it was stated that the air permeability decreased as the CNF-pigment coating rate increased (Xu et al. 2016). The number of coating layers affects the air permeability more than the concentration. Afra et al. (2016) found that increasing the number of layers of CNF coatings and increasing the CNF concentration from 1.5  wt% to 3  wt% increased the air resistance of paper. It was stated that 1.5 wt% double-CNF-layer paper has higher air resistance than 3  wt% single-CNF-layer paper. Hult et  al. (2010) applied CMF coatings on paper samples in single and multiple layers and found that the air permeability decreases as more layers of coating is applied. Tyagi et al. (2019) prepared a double-layer coating which consists of CNF and CNC as individual layers. The air resistance of the coated paper was found increase 300 times compared to that of uncoated paper samples. Also, double-layer coating was found to be more effective in improving the oil and grease resistance and reducing the oxygen tranmission rate. Charani et al. 2013 coated paper samples with CMF by using two methods and found that the coating method was more effective in reducing air permeability compared to the additive method. On the other hand, a couple of studies reported that the air permeability of paper is not affected or even increased after the application of CNF/CNC/CMF/CMC coatings (Lavoine et al. 2014a; Pego et al. 2020; Hubbe et al. 2017). Lavoine et al. (2014a) applied CMF coating on paper substrates in multiple layers, and did not

Nanocellulose in Paper and Board Coating

257

found any significant change in air permeability as the number of coating layers is increased up to ten. This result was attributed to the very low air resistance of the reference cardboard due to its coated front surface for printing and also to the very low weight of the CMF coating compared to the cardboard. Pego et al. (2020) evaluated the air permeability of paper subjected to CNF coating via two approaches, namely, additive and coating methods. They found that the air permeability of paper samples treated by the coating method did not decrease much compared to those subjected to additive method. The result was attributed to the permeable nature of the superficial film layer which forms during the coating method (Pego et al. 2020). Similar findings on the increase in air permeability were also noted by Hubbe et al. (2017). 2.4.1.1.5 Smoothness One of the most important physical properties of paper is the smoothness, which is measured based on the roughness of paper (Afra et al. 2016). Surface smoothness is a desired property in both pirnting and barrier applications (Brodin et al. 2014). The use of CNF/CNC/CMF/CMC as coating material generally increases the smoothness. Cellulose nanofibrils used in the coating process fill the surface pores and form a dense and stable layer on the paper surface (Rezayati Charani et  al. 2013; Afra et al. 2016). Therefore, as the concentration of the coating material and the number of coating layers increases, the smoothness increases. It has been reported that precoating applied before CNF coating increases the surface smoothness of paper (Ridgway and Gane 2012). Afra et  al. (2016) determined that, the smoothness increases as the number of layers and CNF concentration increase. Xu et al. (2016) used CNF as a component in a mineral pigment coating and applied the coating formulation on the paper samples of the Eucalyptus pulps. They determined that smoothness of the coated paper samples improved. Similarly, Beneventi et al. (2014) determined an increase in surface smoothness of the CMF-coated kraft pulp by an average of 27% when the CMF weight was increased from 4 to 40 g/m2. In some studies, the use of CNF/CNC/CMF/CMC as a coating material resulted in either reduction or no change in the smoothness of paper. For example, Tarrés et al. (2022) did not find any change in the smoothness of paper coated with formulation containing CNFM up to 1.5 wt%, while they determined a decrease for the CNFM concentrations of 3 wt% and 4.5 wt%. This results were attributed to the bulk addition of micro- and nanocelluloses together (Tarrés et al. 2022) Pego et al. (2020) determined reduction in the smoothness of papers coated with 10 wt% CNF via the so-called coating method. They speculated that the decrease in smoothness might be due to the differences in paper formation and the uneven distribution of nanocellulose during coating. 2.4.1.2  Mechanical Properties The tensile index, tear index, burst index, internal bond, and crush tests (SCT, CMT, RCT, CCT) are the mechanical properties of the paper.

258

A. Tozluoglu et al.

2.4.1.2.1  Tensile Index Tensile index is used to measure the resistance of fibrous web structure of paper to breaking. Factors such as fiber length, fiber direction, fiber strength, fiber thinning degree, and the filler used are the main factors affecting the tensile strength of paper (Xu et al. 2016). The use of CNF/CNC/CMF/CMC as coating material in paper generally increases the tensile index. Thanks to the high bonding ability of micro/nanofibrils, a strong bonding occurs between the substrate (paper surface) and thus, hard nanofibril layers are formed on the porous cellulosic substrates in the paper. Thanks to this layer, the tensile index value increases (Beneventi et al. 2014; Afra et al. 2016). Afra et al. (2016) stated that 3% CNF coating applied as a double layer increased the tensile index value by 11 Nm/g. Hassan et al. (2016) used CNF and chitosan nanoparticles in increasing concentrations in a coating formulation and determined that the tensile index values increase by 6–40%. The highest increase was determined in the samples coated with formulation containing 10  wt% nanomaterial. Syverud and Stenius (2009) used CNF/starch suspension as a coating material and observed that the coating applied to the paper surface in the range of 2–8  g/m2 slightly increased the tensile index value. Fidan et al. (2021) determined that the pulp slurries containing CNFs which are produced via periodate oxidation showed lower viscosity than the slurries containing other CNF types (TEMPO and PINO oxidation). Due to low viscosity, The low viscosity helps CNF to provide a homogeneous distribution in the starch-based medium. In this way, CNF easily penetrates into the surface, fills the pores, and thus, the tensile index values increase with increasing bond amount (Fidan et al. 2021). A number of studies reported that the tensile index of the paper samples decreased or remained the same when CNF/CNC/CMF/CMC are used as coating materials on paper. Xu et al. (2016) used CNF as a component in a mineral pigment coating and applied the coating formulation on the paper samples. They determined that the tensile index of the paper samples was not affected by the increase in the CNF-­ pigment ratio. Lavoine et al. (2014b) observed that the tensile strength of the specimens decreased in both fiber directions (i.e., machine direction and cross-direction) when CMF coating was applied 5 and 10 times via bar coating and size press applications. Pego et  al. (2020) determined that the tensile index values of the paper samples coated with the slurry of 10-wt% CNF were lower than those of the uncoated samples. 2.4.1.2.2  Tear Index Tear index shows the tearing resistance of the paper sheet. It depends on the fiber length, fiber bonding, fiber strength, fiber thinning degree, and the quality and amount of the filler. Long fibers increase the tear strength by distributing the tension over more bonds, while short fibers decrease it. It is known that the tear strength decreases with the use of filler.

Nanocellulose in Paper and Board Coating

259

The use of CNF/CNC/CMF/CMC as coating material in paper generally decreases or not affect the tear index (Campano et al. 2018; Pego et al. 2020).The mechanical and rheological properties of nanocellulose, the distribution of nanocellulose and the difference in coating methods can affect the mechanical properties of the paper. During coating, agglomeration problems caused by hydrogen bonds and incorrect dispersion may not provide any improvement in the mechanical properties of the paper and may even reduce some properties (tensile strength, tear strength, burst strength, etc.) (Campano et al. 2018). Pego et al. (2020) determined that the tear index of CNF-coated paper samples were lower than the uncoated paper and additive paper. It has been stated that this result may be related to the dispersion of nanocellulose in the coating. 2.4.1.2.3  Burst Index Burst index is known as the minimum hydrostatic pressure required to tear the paper. Parameters such as paper property, fiber type, fiber length, chemical additives, and weight affect burst index. In general, the use of CNF/CNC/CMF/CMC in the coating of paper increases the burst index of paper. Lavoine et al. (2014b) determined that the burst index of the CMF-coated paper specimens were higher than that the uncoated specimens. They also found that the paper samples exhibiting more elongation showed higher burst strength. Fidan et al. (2021) reported that paper samples coated with CNF/starch suspensions via size pressing exhibit burst indices in the range of 2.04–2.65 kPa m2/g. They claimed that the use of starch improved the bonding between the fibers and that the size press application gradually increased the burst index of the paper samples (Fidan et al. 2021). CNF was effective in increasing the burst index by strengthening the interfibrillar connection and forming a tighter network structure (Kumar et al. 2016). The burst index of paper was determined to decrease when it was coated with CNF/CNC/CMF/CMC containing slurries (Lavoine et al. 2014b; Pego et al. 2020). Lavoine et al. (2014b) determined that as the number of CMF-based coating layers on the paper was increased, the burst index of the paper decreased compared to the baseline value given by the uncoated specimen. Considering the expectation that the cellulose microfibrils should strengthen the paper surface, this unexpected decrease in burst index was attributed to the heterogeneity of the CMF layers (the absence of a specific fiber direction). Similarly, Pego et al. (2020) measured lower burst index values on the specimens coated with the slurry of 10-wt% CNF. 2.4.1.2.4  Internal Bond The internal bond measures the amount of force required to delaminate a paper sample. Internal bond, which has an important place among the paper properties, is directly related to the interfiber bond strength and bond amount (Fidan et al. 2021). In the coating processes of paper, poor internal bond causes delamination and seperation (Koubaa and Koran 1995).

260

A. Tozluoglu et al.

The use of CNF/CNC/CMF/CMC as coating material in paper generally increases the internal bond. In the size press application of CNF produced by TEMPO oxidation method, it was observed that the addition of 0.45% CNF and 2.5% starch increased the Scott Bond value by 116% (Tarrés et al. 2016). In a similar study, it was stated that the internal bond values of the papers coated with CNF/ starch suspension increased. Starch helps CNF increase the rate of internal bonding. At the same time, increasing CNF concentration also provides more hydrogen bonding between the fibers, which increases the internal bond value (Fidan et al. 2021). On the other hand, Beneventi et al. (2014) determined a significant decrease in the internal bond values of various paper samples that are treated by CMF coating up to 6 g/m2. The samples with higher amounts of CMF coating, i.e., exceeding 6 g/ m2, did not reveal any significant change in the internal bond values and, thus, reaching an equilibrium in terms of internal bonding (Beneventi et al. 2014). 2.4.1.2.5  Crush Tests (SCT, CMT, RCT, CCT) There are four types of crush tests: short-span compression test (SCT), concora medium test (CMT), ring crush test (RCT), and concora crush test (CCT). These tests are applied mostly on the fabricated papers. Therefore, in the literature, there are few number of studies that investigate the crush tests of nanofibrillated cellulose-­ coated papersheets (Fidan et al. 2021). The use of CNF/CNC/CMF/CMC in the coating of paper generally increases its crush strength. Fidan et  al. (2021) determined that the SCT values of the CNF-­ coated paper specimens increase as ratio of the CNF in the coating slurry increases. The increase in the crush resistance of the samples was attributed to the reduction of the overall strength of the secondary fibers. Fidan et al. (2021) determined that the specimen coated with 4% CNF produced via periodate oxidation revealed the highest increase in the crush resistance measured in the SCT. In the same study, it was stated that the CMT values of the specimens coated with 4% CNF coating were found to increase by 206.8% compared to the papers that were not subjected to the size press. The high water content of CNF suspensions causes water to penetrate into the paper sheet during coating and break the bonds.However, the specific surface area of the CNF allows it to penetrate into the paper and increases the bonds on the inner surface. CMT values increased thanks to the size press of the starch/CNF suspension despite the expected ruptures of bonds. Similarly, the RCT and CCT values of the papers coated with the highest rate (4%) of CNFs were increased by 221.2% and 44.1%, respectively (Fidan et al. 2021). Lavoine et al. (2014a) determined that the short-span compression strength of the water-treated cardboard specimens coated with multiple layers of CMF coating decreased by as much as 20% compared to the SCT value of the reference cardboard. Successive wetting and drying processes reduce cohesion and break hydrogen bonds by opening the fibers. Therefore, the CMF coating combined with water treatment reduces the short-span compression strength of cardboard (Lavoine et al. 2014a).

Nanocellulose in Paper and Board Coating

261

2.4.1.3  Optical Properties The major optical properties of paper are whiteness, brightness, and opacity. These optical properties depend mainly on how paper absorbs and reflects the incident light beams. The use of CNF/CNC/CMF/CMC as coating material in paper generally increases the optical properties of paper. It is known that the addition of thin and small-sized structures to the paper and, thereby, forming a well-structured layer increases its opacity by not allowing light to pass through (Pego et al. 2020). Pego et al. (2020) added 10% CNF as an additive and coating to paper samples prepared from Eucalyptus, Sisal, and Pine fiber sources in different percentages. Higher brightness and lower opacity values were determined in the coating method compared to the additive method. This result is attributed to the nanofilm layer formed on the paper surface and its interaction with light. In general, paper made from coarse fibers is opaque, while paper made from nanofibers is transparent (Zhu et al. 2014). Campano et al. (2018) stated that the brightness of paper generally increases with soaking and pulping time. These two operations, i.e., soaking and pulping, cause swelling of the fibers which in turn makes impurities to be more in contact with water. As a result, these impurities are removed and carried away from the paper by drain water filtered off in paper production. Brodin et al. (2014) stated that the effect of nanocellulose on the optical properties of paper can be predicted. Since nanocellulose is made from bleached pulp, the light adsorption coefficient is generally low. Nanocellulose increases the layer density and bonding area, reduces the specific surface area of the layers, and, thus, reduces the light scattering coefficient of the layer. This result affects the reduction of brightness and opacity. The type of pulp used for the production of nanocellulose, which is used as a coating material, may reduce the brigthness. At the same time, thanks to the translucent nature of the nanocellulose, the gloss and whiteness properties of the paper may not be affected in coating applications (Pego et al. 2020). In a study using CNF-pigment coating material, it was stated that there was no significant change in whiteness when the CNF-pigment ratio is increased. This is attributed to the fact that CNF being colorless (Xu et al. 2016). 2.4.1.4  Barrier (Drainage) Properties The barrier performance of paper is evaluated based on its permeability of water vapor, oxygen, gas, and oil (Dury-Brun et al. 2006). In general, the use of CNF/CNC/CMF/CMC as coating material on paper increases its surface and barrier properties (Ridgway and Gane 2012). It is known that the use of nanocellulose coating material in paper mills has increased recently due to its strong binding effect on paper (Sharma et al. 2020). Oil-proof papers are obtained by applying synthetic polymers with high hydrophobic properties as coatings on paper (Houde et  al. 2006). Aulin et  al. (2010b) used carboxymethylated cellulose nanofibrils as coating material on paper to improve its oxygen and oil

262

A. Tozluoglu et al.

barrier properties. When they tested paper samples for turpentine and castor oil permeability, they determined that the carboxy methylated cellulose nanofibrils play a significant role in making paper oil-proof. Hassan et al. (2016) prepared a coating film containing CNF and chitosan nanoparticles and determined that the paper samples coated with the film reveal excellent oil-proof performance, and this result was attributed to a very tight and closed surface structure with nano-sized pores. Hult et al. (2010) applied Shellac and CMF coating on paper and determined that the oxygen transmission rate decreases and water vapor transmission rate reaches the values (6.5 g/m2, 24 hours) considered as a high barrier in food packaging applications. In another study, it was stated that CNF mixed with clay, as a coating material, improved the print quality properties of the paper, such as print density and ink absorption rate (Hamada et  al. 2010). Tyagi et  al. (2019) used CNF and CNC in paper coatings and determined that the single-layer coating containing CNF exhibited better barrier properties compared to that containing CNC. Oxygen and water vapor permeability of the coating containing CNF decreased more than that containing CNC. The use of CNF and CNC as a double coating on paper was more effective, and the permeability of oxygen and water vapor decreased even further. On the other hand, oil and grease resistance has increased approximately 11 times compared to that of uncoated paper. Based on their findings, Tyagi et  al. (2019) stated that the coating prepared with CNF and CNC will provide a great opportunity for the paper and cardboard industry as an alternative to fluorocarbons used in the food packaging applications. Lavoine et al. (2014a, b) determined no change in the oxygen permeability and grease resistance of paper samples when the samples are treated with a single-layer CMF coating. When the CMF coating was apllied in multiple layers (up to 10 times), however, the oxygen permeability and grease resistance of the coated samples increased slightly (Lavoine et al. 2014a, b). Tyagi et al. (2018) used three different papers with different properties (highest smoothness, highest water absorption and air resistance, most hydrophobic) to examine the barrier performance of CNC-­ based coatings. Besides CNC, montmorillonite (MMT), kaolin clay (K), soy protein (S), and alkyl flax dimer (AKD) were used as ingredients in the coating formulation. They determined that the coating recipe including CNC and K did not yield any significant decrease in the water vapor transmission rate due to the tendency of kaolin particles to come out of the matrix. When MMT, S, and AKD are used along with CNC, however, the water vapor transmission rate decreased (Tyagi et al. 2018).

Nanocellulose in Paper and Board Coating

263

2.5 Effect of Nanocellulose in Paper and Board Production as an Additive 2.5.1 Properties of Nanocellulose Added Paper and Boards 2.5.1.1  Physical Properties 2.5.1.1.1 Thickness The thickness, also known as caliper, is one of the important basic physical properties of paper and paperboard. For a given basis weight, the thickness of paper depends on several parameters such as refined stock, fiber type, dryer temperature, press force, load on the calendars, moister content, and filler content, to name but a few. Thickness is related to the bulk or density of paper. (see URL 2). A well beaten/ refined short-fiber pulp (e.g., hard wood or straw pulps), highly filled or loaded paper will show lower thickness for a given basis weight (see URL 3). As the thickness of paper decreases its opacity increases (Petroudy et al. 2017). The compacted structure of the thinnest handsheet containing CNF is attributed to high adhesion between fiber–fiber, fiber–fibril, and fibril–fibril contacts due to high hydrogen bonding and their ability to form homogeneous, low porosity structures, which leads to less light transmittance capability and thus lowering the opacity of the handsheet (Petroudy et al. 2017). Since the nanopapers are very thin materials, the thickness has a critical effect on the structure, transparency, mechanical and thermomechanical properties, and processing cost of the nanopapers (Li et  al. 2016a, b). Delgado-Aguilar et  al. (2015) determined that as the CNFs obtained from Eucalyptus pulp were mixed with the recycled paper pulp at 4.5 wt%, the thickness of paper decreases from 116.4 to 106.9 μm. González et al. (2013) investigated the effects of enimatic treatment and nanocellulose addition on the mechanical and physical properties of pulp. They observed that the thickness of paper decreased by as much as 15% as the CNF was added to the enzymatic treated and untreated pulps. 2.5.1.1.2 Density In a typical papermaking process, beating increases the density of paper and, thus, decreases the air permeability (Lumiainen 2000). This is mainly related to the increased fibrillation, fiber flexibility, and fines. A similar effect can also be observed by increasing the CMF/CNF content (Taipale et al. 2010). Ämmälä et  al. (2013) studied effect of tempo and periodate-chlorite oxidized nanofibrils on ground calcium carbonate flocculation and retention in sheet forming and on the physical properties of sheets. They found that the sheets with CNF are slightly denser (except for the TEMPO 2%) compared to the sheets without CNF.  The experiments were carried out with sheets produced from refined kraft fibers and ground calcium carbonate (GCC) with the addition of TEMPO and DCC (periodate-chlorite oxidized) nanofibrils at various doses. The results showed that,

264

A. Tozluoglu et al.

for the same filler content, the sheets with CNF are slightly denser and they reveal slightly better internal bonding ability compared to the reference sheet. Delgado-Aguilar et al. (2015) studied the use of CNF as an alternative to mechanical beating to improve the properties of paper produced from a deinked recycled pulp (DIP). They found that the paper produced from CNF-reinforced DIP exhibits significantly higher strength than that produced from mechanically beaten DIP of similar density. CNF-reinforced papers were stiffer, denser, and less porous compared to those produced from the beaten DIP. 2.5.1.1.3 Bulk The basic aim in the papermaking industry is to be able to use larger amounts of filler in paper without adversely affecting the other mechanical properties (e.g., strength) and bulk (Lourenço et al. 2017). Lourenço et al. (2019) studied on the production of cellulose nanofibrils (CNF) from bleached Eucalyptus kraft pulp by carboxymethylation and TEMPO-mediated oxidation followed by high pressure homogenization. The addition of nanocellulose filling material to the papers using different filling materials (containing only precipitated calcium carbonate in the reference and precipitated calcium carbonate, cationic starch, alkenyl succinic anhydride, cationic polyacrylamide in the reference) decreased the bulk values. Delgado-Aguilar et al. (2015) determined reduction in the bulk values of paper handsheets as the concentration of TEMPO-CNF added to recycled paper pulp increased. 2.5.1.1.4  Air Permeability and Smoothness For papermakers, the apparent density and air permeability of paper are two important parameters. Rasi (2013) studied the permeability properties of paper materials and determined that the air permeability of paper increases after many cycles of rewetting and redrying during the production process. Compared to water permeability, however, the air permeability was moderate. The air permeability of paper indicates not only the porosity (void volume/total volume) of paper but also the complexity of its network structure (He et al. 2017). It has been reported in many studies that the density of paper increased while the air permeability of the paper decreased with the addition of CNF (Eriksen et  al. 2008; Taipale et al. 2010). Lourenço et al. (2019) determined that the addition of nanocellulose filling material to the papers significantly increased the air permeability and smoothness values. Kasmani and Samariha (2019) added nanocelluloses produced by the super-­ pounding method to the paper at different ratios. They determined that the nanocellulose added at the rate of 8% increased the air resistance and smoothness of paper by as much as 23.6% and 11.1%, respectively. Adnan et al. (2018) stated that the air permeability of a paper can be reduced by 50% by adding 10  wt% of nanocellulose to the paper pulp. The reduction in air

Nanocellulose in Paper and Board Coating

265

permeability reduces bacterial activities and, thus, prevents the deterioration of food and pharmaceutical products in their packaging. In another study, it was stated that porosity values ​​decreased when two different nanocelluloses obtained from Eucalyptus Kraft pulp and bleached pine pulp by TEMPO oxidation and homogenization processes were added to the paper at the rates of 3%, 4.5%, and 6% (Balea et al. 2016a). In the paper production process, nanofibrils are positioned on the fibers and block the pores. Subramanian et al. (2007) examined the precipitation of PCC – pulp composite fillers with varying crystal habits and their effects on the papermaking properties of printing and writing paper. Colloidal (c-PCC), rhombohedral (r-PCC), and scalenohedral types (s-PCC) of composite PCCs were produced and compared with commercial reference PCCs. As a reference filler, however, the addition of s-PCC caused a significant increase in the air permeability and a decrease in density of paper. Addition of colloidal PCC resulted in a minimal increase in the air permeability of the paper (Subramanian et al. 2007). 2.5.1.2  Mechanical Properties

2.5.1.2.1  Tensile Index The tensile index is an indicator of the resistance of paper under tensile stress. The most important factor which affects this resistance is the fiber connections (González et al. 2012). CNF offers some interesting properties for papermaking such as large specific surface area and high aspect ratio, and also this material has an ability to form a cross-linked network with pseudoplastic behavior (Taipale et  al. 2010). Because of this reason, when CNF is used in fiber slurries it enhances the tensile strength and reduces porosity of the final paper sheet (Ahola et al. 2008a; Eriksen et al. 2008; Yoo and Hsieh 2010; Sehaqui et al. 2011b; Taipale et al. 2010; González et al. 2012). In addition, the enlargement in the number and the frequency of fiber-­ to-­fiber bonds plays a major role in the enhancement of tensile strength of paper (Dasgupta 1994). Kasmani and Samariha (2019) used CMP pulp, cationic starch, and nanocellulosic gel to prepare 60 g/m2 handsheets. The fiber suspension was placed in a mixer, 1% cationic starch was added, and then various concentrations (0%, 2%, 4%, 6%, and 8%) of CNF were added to the mixture of CMP pulp. The highest value for tensile strength (33.6 Nm/g) was observed in the samples containing 8% CNF and the lowest tensile strength (30.3 Nm/g) was observed in the neat samples (i.e., with the 0% CNF treatment). Delgado-Aguilar et al. (2015) studied the use of CNF as an alternative to mechanical beating to improve the properties of paper produced from a deinked recycled pulp (DIP). The tensile strength and Young’s modulus increased linearly with increasing CNF concentration. Accordingly, the samples containing 9  wt% CNF revealed improvements in tensile strength and Young’s modulus up to 150% and

266

A. Tozluoglu et al.

60%, respectively. Such improvements were attributed to four main factors: the presence of nanofibrils with high intrinsic mechanical properties, high specific surface area in the slurry that boosts the number of hydrogen bonds, uniform stress distribution across the paper structure, and reduction of voids between the fibers (Delgado-Aguilar et al. 2015). Considering the paper obtained from the pulp beaten at 1500 revolutions as a reference, the addition of only 0.5  wt% CNF was sufficient to match the tensile index obtained from the reference sample. The tensile index of the beaten pulp was observed as 36.93 Nm/g, and the addition of 1.5 wt% CNF increased the tensile index up to 45.62 Nm/g. The tensile strength, however, decreased almost linearly with increasing filler content in some experiments (Ämmälä et al. 2013). This quite well-known behavior is attributed to the fact that the filler material deposited on the fibers prevents hydrogen bonds from forming in the deposition sites. 2.5.1.2.2  Tear Index Tear strength is affected by various factors and many research efforts demonstrated that tear strength is mainly affected by the fiber length and the level of hydrogen bonding. Increment of lignocellulosic nanofibers increases the level of hydrogen bonding and decreases the mean length of the fibers; therefore, the tear strength rises and falls irregularly. On the other hand, increasing the CNF content can lead to the reduction of tear strength because of enhancement of the level of hydrogen bonding. (Kasmani and Samariha 2019). Hadilam et al. (2013) reported that addition of cellulosic nanofibers can reduce the tear strength and the lowest measurements can be obtained from the samples of nanopapers and nanoboards. Kasmani and Samariha (2019) observed that the addition of CNF at 8  wt% resulted in a 10.4% reduction in the tear strength compared to the tear strength of pristine specimen (0% CNF). Delgado-Aguilar et al. (2015) observed the tear index as a function of the fiber strength, fiber length, and bonding degree between cellulosic components. They determined that the tear index of the deinked recycled pulp (DIP)suspensions showed a slight decrease during the first beating step and dropped rather significantly in the subsequent beating levels. Pulps with a low degree of bonding generally show increase in the tear index upon mechanical beating since the process gives rise to hydration and swelling. ​However, the tear index declined with the addition of 1.5 wt% CNF, then stayed stable with the subsequent CNF additions. The tear index of mechanically beaten pulp (1500 rev.) was observed to be 7.1 mN.m2/g and the addition of 1.5 wt% CNF decreased the tear index to 6.2 mN.m2/g (Delgado-­Aguilar et al. 2015). On the other hand, Berrocal et al. (2004) reported a different behavior in the tear index such that the pretreatment of wheat straw with Streptomyces cyaneus and soda cooking had an improving effect on the tear index of the handsheets.

Nanocellulose in Paper and Board Coating

267

2.5.1.2.3  Burst Index Burst strength depends on the fiber length and the bond between the fibers. The burst index is proportional to the square of the average fiber length (Ashori and Raverty 2007). In general, the breaking length, tear index, and the burst index all improve with the addition of CNF (Espinosa et al. 2017). Kasmani and Samariha (2019) investigated the effect of nanofibrillated cellulose (CNF) relative to the strength of chemi-mechanical pulp (CMP) and paper within the scope of their work. According to their results, the addition of CNF at the 8% level increased the burst strength by 12.5% compared to the neat sample containing 0% CNF.  The highest bursting strength was recorded in the control sample (1.4 kPa/g) and the lowest bursting strength was observed in the sample with 0% CNF treatment (1.2 kPa/g). The burst index, which measures the maximum perpendicular pressure that paper is able to resist before rupture, was increased by around 16% with beating, a minor improvement than what is achieved by pristine pulps beaten at the same density. According to Delgado-Aguilar et al. (2015), the burst index increased upon addition of the CNF. The effect of 1.5% CNF addition on the burst index was equivalent to the burst index of reference paper subjected to mechanical beating. Balea et  al. (2016b) added two different nanocelluloses (CNF-E and CNF-P), which are obtained from bleached Eucalyptus Kraft pulp and bleached pine pulp after TEMPO oxidation and homogenization processes, to paper at the rates of 3%, 4.5%, and 6%. Addition of 4.5% CNF-E to the paper increased its burst index by more than 50%, and after this rate, slight increases in burst value were observed. Addition of 4.5% CNF-P resulted in an increase of close to 46%. In another study, it was determined that the burst index value increased when the nanocellulose obtained by enzymatic treatment was added to the paper at the rates of 0%, 1.5%, 3%, and 4.5%. Espinosa et al. (2017) stated that the nanocelluloses produced by mechanical and enzymatic pretreatments increased the burst index value with the increase in their concentration. Nanocellulose produced by TEMPO oxidation decreased the burst index value after loading of 3 wt%. In a similar study, nanocelluloses obtained by carboxymethylation and TEMPO oxidation decreased the burst index (Lourenço et al. 2019). 2.5.1.2.4  Internal Bond The internal bond (Scott bond) is closely related to the bonding capacity of paper components which are external fibrils and fines primarily (González et al. 2012). The Scott bond test indicated an improvement in both the number of bonds and the bonded area between the fibers (Kang and Paulapuro 2006). This means that higher energy is required for the delamination of the testing sheet (Delgado-Aguilar et  al. 2015). González et  al. (2012) have compared CNF-reinforced bleached Eucalyptus pulps with traditional beaten pulps used for producing writing/printing and offset printing papers. In this study, they used dried, bleached Eucalyptus pulp as the primary material. First, the fiber slurry (10% wt) was mechanically beaten at

268

A. Tozluoglu et al.

1000, 1250, 2500, and 3750 revolutions. Silica colloidal and cationic starch were added to the beaten slurry as retention agents in amounts of 0.8% and 0.5% wt after the stirring process. Secondly, for the CNF-reinforced papers, the TEMPO-mediated CNF (3%, 6% and 9% wt) was added to the unbeaten slurry during the disintegration process. As a third approach, Eucalyptus slurry was slightly beaten and reinforced with the CNF up to 6% wt. According to the Scott bond test results obtained from the handsheets, the samples beaten at 1250 revolutions showed increases of 393%, rising to 905% at 2500 revolutions, and to 1409% at 3750 revolutions compared with the unbeaten samples. The slurry reinforced with 9% CNF demonstrated an internal cohesion (469 J/m2) of almost 6.5 times more than that of suspension without any reinforcement. The internal cohesion or Scott bond of slightly beaten and CNF-reinforced handsheets showed the highest value (976.8 J/m2) at the dose of 6% wt CNF. In their study, González et al. (2013) used dried bleached Eucalyptus pulp as a raw material for the preparation of CNF and paper sheets. TEMPO oxidation process was performed as reported by Besbes et al. (2011). Then, as a biobeating process, an enzymatic treatment was applied. As retention agents, colloidal silica and cationic starch were then added into enzyme-treated pulp in amounts of 0.8 and 0.5 wt%. Finally, CNF was added to handsheets with 0, 1.5, 3, 4.5% wt. The test result of the paper sheets (75 g/m2) show that the scott bond of enzymatic-treated and 4.5%-CNF-added sample (356 J/m2) was nearly 7 times higher than that of the untreated pulp (51.9 J/m2). Delgado-Aguilar et al. (2015) investigated the effect of addition of CNF into a deinked recycled pulp (DIP) suspension obtained from disintegration and flotation of a mixture formed by old newspapers (ONP) and old magazines (OMG). The present work studied the suitability of CNF as an additive in papermaking suspensions based on the recycled newspapers and magazines, and its effects were compared with soft mechanical beating. The increase in the strength of paper was significantly higher compared to the beaten DIP with similar density. According to their results, four different levels of beating were analyzed (0, 500, 1000, 1500 rev) and four different concentrations of CNF (0, 1.5, 3, 4.5 wt%) were used as a comparison parameter. Their results show that the scott bond values associated with the out-of-plane strength increased linearly with the addition of CNF, as it occurred with beating DIP. Fibers on OMP presented a less directed orientation and greater resistance in Z-direction, i.e., Scott bond value, than ONP. The same results show that while beating DIP at 1500 revolutions increased the scott bond by around 22.63%, the addition of 1.5 wt% CNF increased the scott bond (24.38%) by nearly the same rate of beating. 2.5.1.2.5  Crush Tests (SCT, CMT, RCT, CCT)

Short Span Compression Test (SCT)

The short span compression test (SCT) was developed to measure the compressive strength of paperboard and corrugated board which are intended to be used as

Nanocellulose in Paper and Board Coating

269

packaging material. The result from the test is referred to as the SCT-value (Psct), which is the maximum force measured during the test divided by the width of the specimen. (Hämäläinen et al. 2017). Balea et al. (2016c) found an increase of up to 40% in the SCT value when they added 4.5% CNFs produced from bleached eucalyptus kraft pulp and bleached pine pulp to pulp fibers obtained from waste cardboard papers. Also, Balea et al. (2019) increased SCT value up to 20% when they added the CNFs obtained after TEMPO oxidation from these fiber sources to waste newsprint and old corrugated cardboard fibers at the rate of 1, 2, and 3 wt%. Ehman et al. (2020) obtained CNFs from pine kraft pulp fibers and the CNFs to the chemical-mechanical pulp fibers at the rate of 3%. They observed a 23.0% increase in the SCT values ​​(21.9 Nm/g) of the paper produced in 125 g/m2 weight compared to the SCT of the control sample (17.8 Nm/g). Sanchez-Salvador et al. (2020), on the other hand, added the CNF obtained from bleached coniferous kraft pulp fibers to waste cardboard pulp fibers at the rate of 1.5%, 3%, 4.5%, and 6%, and observed that the SCT value increased by 12.3%, 16.3%, 19.0%, and 23.4%. Concora Medium Test (CMT) The concora medium test (CMT) allows the evaluation of corrugating medium before it is fabricated into the final product. The edgewise compression strength of corrugated board is a principal element in determining the dynamic compression strength of the container made from a board. Since the corrugated cardboards are frequently subjected to loads which are resisted by compression strength, the CMT is a main measure of the performance characteristic of corrugated cardboards and is useful in measuring the quality of the finished product (Ghasemian et  al. 2012; Biricik and Atik 2012). Sheikhi et al. (2013) examined the CMT value as 64.5 N in the papers they produced from old corrugated cardboard with a weight of 120 g/m2. Within the scope of the study, CMT values obtained from control fluting papers were found to be similar to the values reported in other studies in the literature (Sarkhosh Rahmani and Talaeipoor 2011; Ghasemian et al. 2012). There are also studies in which higher CMT values (145 N) were obtained by using waste paper fibers (Masrol et al. 2016). Ehman et  al. (2020) added the CNFs obtained from pine kraft pulp fibers by TEMPO oxidation to the leafy wood chemical mechanical pulp at a rate of 3 wt%. They found that the CMT of the paper samples weighing 125 g/m2is higher than the CMT of control sample by as much as 27.4%. Ring Crush Test (RCT). The ring crush test is regarded as an effective method to evaluate the contribution of materials to the compressive strength of corrugated boxes. The RCT index in pulps with nanofibers is generally higher than that of the control samples without nanofibers.

270

A. Tozluoglu et al.

Ehman et al. (2020) measured the RCT index of the papers containing 3 wt% CNF and determined an increase of 28.2% compared to the RCT index of the control samples. Fidan et al. (2021) reported the effects of CNF on the mechanical and physical properties of the recycled pulp papers. Accordingly, they found that the control coreboard papers (4.58 Nm/g) exhibited lower RCT values than the control fluting papers (5.67 Nm/g). The results of this study were in parallel with the previous studies. For example, Tutuş et al. (2016) obtained the RCT values falling into the range of 4.44–8.07 Nm/g in fluting papers of different basis weights (90–175 g/m2). On the other hand, the addition of CNF/CNF-OX to the bulk suspensions of the control coreboard and control fluting pulp fibers increased the RCT values. The RCT values of the handsheets produced with different types of CNF/CNF-OX to the bulk suspensions of the control coreboard papers (4.58  Nm/g) and control fluting papers (5.67  N  m/g) at 0.5%, 1%, 2%, 3%, and 4% (oven dried) ranged from 4.63 to 5.39 Nm/g and 5.86 to 6.88 Nm/g, respectively. Corrugated Crush Test (CCT). Corrugated (or “Concora”) crush test is used to measure the edgewise compression strength of a laboratory-fluted strip of a corrugating medium. The CCT measures the compressive performance of corrugated box (see URL 4). Hietala et  al. (2016) have prepared nanofibrillated dicarboxyl acid cellulose (DCC-CNF) by using sequential periodate–chlorite oxidation followed by nanofibrillation using either microfluidization or high-pressure homogenization. The compression strength of the specimens was analyzed using the corrugated crush test, CCT. According to their results, the CCT values of the specimens increased when the DCC-CNFs were added. The greatest increase in the compression strength properties was obtained in the specimens containing the homogenized DCC (32% increase with 2 wt% DCC-H). When the microfluidized DCC CNF (DCC-M) was added, the increase in the CCT index was somewhat lower (22% with 2 wt% DCC-­ M). Moreover, higher DCC-M CNF content (1 wt%) in the handsheets was required to obtain a definite increase in the CCT strength properties. Fidan et al. (2021), as mentioned before, studied the effects of the CNF (isolated from wheat straw via chemically and enzymatically) on the mechanical and physical properties of the recycled pulp papers. The results show that the control coreboard papers (6.41  Nm/g) indicated lower CCT values than the control fluting papers (6.60  Nm/g). The results of this study corroborated the previous studies. Tutuş et  al. (2016) reported CCT values between 10.4 and 16.2  Nm/g in fluting papers of different basis weights (90–175 g/m2) with the addition of starch in the bulk suspensions of waste paper fibers. On the other hand, the addition of different types of CNF/CNF-OX to the pulp suspensions of the control coreboard and control fluting pulp fibers increased the CCT values. The CCT values of the handsheets with the addition of different types of CNF/CNF-OX in the pulp suspensions of the control coreboard papers (6.41  Nm/g) and control fluting papers (6.60  Nm/g) at 0.5%, 1%, 2%, 3%, and 4% (oven dried) ranged from 6.57 to 8.31 Nm/g and 7.23 to 9.52 Nm/g, respectively. The highest increase in CCT values occurred with the addition of 4% of AHn (29.6%) to the control coreboard pulp fibers and 4% of AHEn4 (44.1%) to the control fluting pulp fibers.

Nanocellulose in Paper and Board Coating

271

2.5.1.3  Optical Properties

2.5.1.3.1 Brightness Brightness is a paper property that is associated with the light beams reflected by fibers, fines, and fillers in the sheet. The nanofibrils, however, are too small to reflect or disperse high amounts of visible radiation (λ > 600 nm). Therefore, nanofibrils are transparent to visible radiation and high amount of CNFs with such small dimensions lead to reduced brightness. Balea et al. (2016b) used the CNFs extracted from eucalyptus kraft pulp (E-CNF) as reference. Addition of 0.5% wt. CNF produced from corn organosolv pulp (C-CNF) to recycled paper slightly reduced brightness as expected by its higher Kappa index. The C-CNF contains some residues of colored compounds which reduce the brightness. On the other hand, low doses of E-CNF did not decrease the brightness because it does not have impurities. But when the samples containing high doses of E-CNF were tested, the brightness was found to reduce more than the reduction obtained in the samples containing C-CNF. When high doses of E-CNF are added, their distribution in the pulp may be very slow due to its high viscosity. As a result, less bright and more transparent regions with higher E-CNF concentration will increase in number. Low doses of C-CNF have not affected the brightness greatly (Balea et al. 2016b). Latifah et al. (2020) used CNF prepared from bleached kelempayan (Neolamarckia cadamba) pulp in their study. The resulting CNF was added into laboratory handsheets (60  g/m2) at 2, 4, 6, 8, and 10  wt%. The results showed that addition of 2–10 wt% CNF did not have much effect on the brightness as the change was too small to detect. In another study, the effect of nanofibrillated cellulose (CNF) was investigated relative to the strength of chemi-mechanical pulp (CMP) and paper. The CNF was added at five levels: 0%, 2%, 4%, 6%, and 8%. Handsheets with a basis weight of 60 g/m2 were prepared and the brightness was measured according to TAPPI standards. By increasing the CNF content, the brightness increased by 3.5% compared to the brightness of the control (0% CNF) samples (Kasmani and Samariha 2019). 2.5.1.3.2 Opacity Opacity of a paper is a quantitative measure of how effectively the paper blocks the transmission of light through itself. In other words, opacity is the ability of paper to hide or mask a color or object in the back of the sheet. It is an essential property in printing papers since a high opacity in printed paper allows one to read the front side of the page without being distracted by print images on the back side (Bajpai 2018). Opacity is affected by thickness, fillers, and extent of beating and bleaching. The higher the opacity the lower the visibility of an object through the paper. In their study, Latifah et al. (2020) used CNFs prepared from bleached kelempayan (Neolamarckia cadamba) pulp. The resulting CNF was added into laboratory

272

A. Tozluoglu et al.

handsheets (60 g/m2) at 2, 4, 6, 8, and 10 wt%. According to standard method MS ISO 2471:2010 the results showed that the addition of CNF into the paper pulp did not change the opacity value considerably. According to Bharimalla et al. (2017) the optical properties of a paper are sensitive to its internal structure and depend on the scattering of light from the exposed fiber surfaces on the sheet. For optical properties, the most important structural aspect is the number of pores along the photon flight path. González et al. (2012) reported that the physical and mechanical properties of bleached Eucalyptus pulp reinforced with nanofibrillated cellulose (CNF) were compared with traditional beaten pulp used in the making of writing/printing and offset printing papers. In this study, three different types of hardwood slurries were prepared: beaten pulps, unbeaten pulps reinforced with CNF, and slightly beaten pulps also reinforced with CNF. According to optical tests on handsheets from these different slurries; the best results were obtained in slurries previously beaten under slight conditions and subsequently reinforced with CNF. The results obtained in the samples containing 9 wt% CNF (subjected to beating at 2500 and 3750 revolutions) showed that the addition of CNF resulted in a reduction in beating intensity without decreasing the preferred properties for this specific purpose. As a consequence, several recent studies have verified the suitability of applying CNF to pulp slurries as a way to improve strength and opacity of the paper (González et al. 2012). 2.5.1.4  Barrier (Drainage) Properties Drainage is a critical parameter in papermaking process as it limits the production efficiency of the paper machine (Norell et al. 1999). In papermaking, it is a very challenging task to improve the physical properties of paper without degenerating drainage properties (Hubbe and Heitmann 2007). The water connected to the fibers usually exists in three forms: free, absorbed, and bound water. Removal of absorbed and bound water requires an increased difference in both pressure and temperature, which can be achieved in the press and dryer sections of the paper machine (Unbehend and Britt 1982; Britt et al. 1986). As studied earlier; dry strength additives (starch) and chemical pulp fines are used to reduce the energy required for beating or fibrillation of pulp and also to produce cellulose fibers. According to the hypotheses of the researchers and the research results, it was claimed that CMF and CNF could be added to the pulp suspension to improve the physical properties of the paper. In general, the addition of CMF to the pulp suspension reduces the drainage rate. Micro- or nanofibrils (Wågberg et  al. 1987, 2008; Henriksson et al. 2008; Ahola et al. 2008a, b; Aulin et al. 2009), which have improved anionic character swelling properties as well as smaller and uniform dimensions, have been used to reduce the energy necessity of beating or fibrillation of pulp and to produce cellulose fibers. In industrial applications, CMF’s strong water retention can outweigh the benefits achieved. Therefore, it is important to

Nanocellulose in Paper and Board Coating

273

comprehensively investigate the relationship between the drainage properties and the strength increase to facilitate the use of this biomaterial. In a study conducted by Taipale et al. (2010), the ECF (elemental chlorine free) bleached softwood kraft pulp was beated for 10 and 30  minutes to have an idea about the effect of beating and to compare results with the samples containing CMF and CS (Taipale et al. 2010). Optimum CMF content in this experiment was found to be 30  mg/g-pulp. At this concentration, a significant improvement in paper strength was observed without having a considerable loss in the drainage rate. Further increase in the CMF content resulted in a significant increase in the drainage time. It should be noted that the optimum concentration depends on the degree of beating, properties of CMF, or ionic strength. It was also stated that the addition of CS and CMF increases the paper strength. As it was found that the addition of CMF broke down the drainage properties of pulp suspension, the effect of CS and CMF addition and the type of CMF on the drainage and strength properties also studied further. For the 30-minute beaten pulp, the drainage rate was strongly dependent on the type of CMF used but the strength properties were not affected by the CMF type. The drainage rate obtained in the 10-minute beaten pulp was less affected by the CMF type but a large difference in the strength properties was found between the different types of CMFs. Balea et al. (2016c) investigated the effect of nanocellulose on the retention and drainage of recycled paper in the presence of different adhesion agents (cationic starch, polyacrylamide, polyvinylamine). They obtained the nanocellulose from organosolv corn stalk pulp via TEMPO oxidation method. It was stated that in the presence of cationic starch, the drainage time first increased as the CNF concentration was increased up to 1.5 wt% and then decreased at the CNF concentration of 3 wt%. It was stated that the drainage time decreased with increasing concentration of CNF in the presence of polyacrylamide and polyvinylamine. The drainage of a CMF containing pulp suspension is strongly influenced by the prevailing conditions such as pH, salt concentration, cationic polyelectrolyte type, CMF content, and beating level of the pulp. The properties of CMF vary according to its raw material, production method, and possible modifications. Under stationary conditions, the type of CMF has a strong influence on both the drainage of pulp suspension and the strength properties of paper. Optimal use of CMF materials and processing conditions can improve the strength properties of the paper without adversely affecting the drainage properties of the pulp suspension (Taipale et al. 2010).

274

A. Tozluoglu et al.

2.6 Application Drawbacks of Nanocellulose in Paper and Board Production and Coating CNF is usually extracted from the lignocellulosic biomass, mostly obtained from wood pulps. High-pressure homogenizers are effectively used in the extraction CNFs. The main disadvantage of the homogenizers is the necessity of high energy and the clogging problems during its production (Thomas et al. 2020). Last few years, many researchers studied on different mechanical instruments, such as ultrasonication, steam explosion, microfluidizers, and ball milling for extracting cellulose from biomass (Abdul Khalil et al. 2014a, b; Kim et al. 2015a, b; Jonoobi et al. 2015; Nechyporchuk and Belgacem 2016). Although these techniques have better processing capabilities, the demand for high energy necessities and the presence of larger fragments cause some problems. The significant challenges related to industrialization and commercialization of the nanocellulose are mainly associated with transportation, which is a major issue for wet CMF/CNF. The low solid content of commercialized CNF limits the commercial exchange and affects product quality because CNF suspension should be used immediately or there is a requirement to add an agent for keeping the material good (Oksman et al. 2014). Therefore, it is difficult to estimate the end-user price of the nanocellulose products. It is, however, estimated to be in the range of US$7 to 12 per kg of dried material (Chauve and Bras 2014). Nonetheless, the CNF-based materials still have disadvantages such as high cost, water content, and brittle nature, creating barriers for the industrial-scale production. Humidity plasticizes the amorphous regions in the cellulose and causes reduction in the strength and stiffness (Benítez et al. 2013). In addition to these drawbacks, when we look at the production processes, the main problem of the implementation of CNFs in paper making process is the reduction of dewatering (Brodin and Eriksen 2015). The main reasons of the dewatering problem are the plugging of interfiber pores, length of capillaries required for water flow, and reduction of sheet’s air permeability (Taipale et al. 2010; Rantanen and Maloney 2013). The carboxymethylated nanofibers are known to contribute to the reduction of drainability (Boufi et al. 2016). Drainage can be improved by selecting appropriate type and correct dosing of retention agents so that nanofibers can be adsorbed onto the fiber’s surface (Taipale et al. 2010; Ahola et al. 2008b; Su et al. 2014). To overcome the problem of high energy consumption, enzymatic or chemical pretreatment methods before mechanical treatment has been proposed by researchers (Isogai 2013; Chinga-Carrasco 2014). On the other hand, one of the major drawbacks of using CNF in paper making slurry is the adverse effect of the CNF on the drainability of paper. In a review article, Boufi et  al. (2016) discussed the role of CNF as an additive material in papermaking processes. The use of retention agent supporting the slurry was put forth as a solution to drainability issue. On the other hand, the retention agent was found to have a negative impact on the mechanical properties of the final paper product.

Nanocellulose in Paper and Board Coating

275

Many researchers have strived to reduce the amount of energy required in different segments the overall production system. Aracri et al. (2012) reported TEMPO-­ mediated oxidation as an effective tool to improve paper strength produced from sisal fiber. Besides enzymatic treatment methods, there are other known methods including periodate-chlorite oxidation, carboxymethylation, and acetylation. Weak retention of CNFs on the fibers has been reported as another disadvantage of using nanocellulose in the paper production. Because of the abovementioned drawbacks, the use of nanocellulose in papermaking has been limited to pilot-scale productions, rather than commercial-scale (Al-ahmed and Inamuddin 2020). Consequently, the development of sustainable applications depends on end-to-­ end issues such as raw material selection, extraction methods, product design, and life cycle. Many different applications contain the integration of functional and advanced properties of these materials in order to promote environmental and economic benefits. The productive design process for the development of useful products from nanocellulose materials suitable for different fields depends on the classification and resolution of actual problems. This also requires multidisciplinary research efforts on the use of nanocellulose for sustainable applications. Commercial production of nanocellulose-based materials aiming at different end-user applications will be realized in the near future thanks to the development in global technology and strong collaboration between industries and academia (Reshmy et al. 2020).

References Abdelmouleh M, Boufi S, Salah AB, Belgacem MN, Gandini A (2002) Interaction of silane coupling agents with cellulose. Langmuir 18:3203–3208 Abdul Khalil HPS, Davoudpour Y, Islam MN, Mustapha A, Sudesh K, Dungani R, Jawaid M (2014a) Production and modification of nanofibrillated cellulose using various mechanical processes: a review. Carbohydr Polym 99:649–665 Abdul Khalil HPS, Davoudpour Y, Sri Aprilia NA, Mustapha A, Hossain S, Islam N, Dungani R (2014b) Nanocellulose-based polymer nanocomposite: isolation, characterization and applications. In: Thakurpp VK (ed) Nanocellulose polymer nanocomposites: fundamentals and applications. Wiley, Hoboken, NJ, pp 290–292 Abe K, Yano H (2011) Formation of hydrogels from cellulose nanofibers. Carbohydr Polym 85(4):733–737 Abe K, Yano H (2012) Cellulose nanofiber-based hydrogels with high mechanical strength. Cellulose 19(6):1907–1912 Abitbol T, Kloser E, Gray DG (2013) Estimation of the surface sulfur content of cellulose nanocrystals prepared by sulfuric acid hydrolysis. Cellulose 20(2):785–794 Achtel C, Heinze T (2016) Homogeneous acetylation of cellulose in the new solvent triethyloctylammonium chloride in combination with organic liquids. Macromol Chem Phys 217:2041–2048 Adnan S, Azhar AH, Jasmani L, Samsudin MF (2018) Properties of paper incorporated with nanocellulose extracted using microbial hydrolysis assisted shear process. IOP Conf Ser Mater Sci Eng 368:012022 Afra E, Mohammadnejad S, Saraeyan A (2016) Cellulose neanofibils as coating material and its effects on paper properties. Pro Org Coat 101:455–460

276

A. Tozluoglu et al.

Ahmadi M, Madadlou A, Saboury AA (2016) Whey protein aerogel as blended with cellulose crystalline particles or loaded with fish oil. Food Chem 196:1016–1022 Ahola S, Österberg M, Laine J (2008a) Cellulose nanofibrils adsorption with poly(amide -amine) epichlorohydrin studied by QCM-D and application as a paper strength additive. Cellulose 15:303–314 Ahola S, Salmi J, Johansson L-S, Laine J, Österberg M (2008b) Model films from native cellulose nanofibrils, preparation, swelling, and surface interactions. Biomacromolecules 9(4):1273–1282 Ajdary R, Huan S, Ezazi NZ, Xiang W, Grande R, Santos HA, Orlando J (2019) Rojas acetylated nanocellulose for single-component bioinks and cell proliferation on 3D-printed scaffolds. Biomacromolecules 20(7):2770–2778 Al-ahmed A, Inamuddin (2020) Advanced applications of polysaccharides and their composites. Mater Res Forum LLC 73:248 Alemdar A, Sain M (2008a) Biocomposites from wheat straw nanofibers: morphology, thermal and mechanical properties. Compos Sci Technol 68:557–565 Alemdar A, Sain M (2008b) Isolation and characterization of nanofibers from agricultural residues-­ wheat straw and soy hulls. Bioresour Technol 99(6):1664–1671 Amini E, Tajvidi M, Gardner DJ, Bousfield DW (2017) Utilization of cellulose nanofibrils as a binder for particleboard manufacture. Bioresources 12:4093–4110 Ämmälä A, Liimatainen H, Burmeister C, Niinimaki J (2013) Effect of TEMPO and periodate-­ chlorite oxidized nanofibrils on ground calcium carbonate flocculation and retention in sheet forming and the physical properties of sheets. Cellulose 20:2451–2460 Andresen M, Stenius P (2007) Water-in-oil emulsions stabilized by hydrophobized microfibrillated cellulose. J Dispers Sci Technol 28(6):837–844 Andresen M, Johansson LS, Tanem BS, Stenius P (2006) Properties and characterization of hydrophobized microfibrillated cellulose. Cellulose 13:665–677 Anirudhan TS, Rejeena SR, Binusree J (2013) Adsorptive separation of myoglobin from aqueous solutions using iron oxide magnetic nanoparticles modified with functionalized nanocrystalline cellulose. J Chem Eng Data 58(5):1329–1339 Antov P, Jivkov V, Savov V, Simeonova R, Yavorov N (2020) Structural application of eco-­ friendly composites from recycled wood fibres bonded with magnesium lignosulfonate. Appl Sci 10:7526 Antov P, Savov V, Trichkov N, Krišťák Ľ, Réh R, Papadopoulos AN, Taghiyari HR, Pizzi A, Kunecová D, Pachikova M (2021) Properties of high-density fiberboard bonded with urea–formaldehyde resin and ammonium lignosulfonate as a bio-based additive. Polymers 13(16):2775 Aracri E, Valls C, Vidal T (2012) Paper strength improvement by oxidative modification of sisal cellulose fibers with laccase—TEMPO system: influence of the process variables. Carbohydr Polym 88:830–837 Araki J, Wada M, Kuga S, Okano T (1999) Influence of surface charge on viscosity behavior of cellulose microcrystal suspension. J Wood Sci 45(3):258–261 Araki J, Wada M, Kuga S (2001) Steric stabilization of a cellulose microcrystal suspension by poly(ethylene glycol) grafting. Langmuir 17:21–27 Ashori A, Raverty WD (2007) Printability of sized Kenaf (Hibiscus cannabinus) papers. Polym-­ Plast Technol Eng 46(7):683–687 Ashori A, Babaee M, Jonoobi M, Hamzeh Y (2014) Solvent-free acetylation of cellulose nanofibers for improving compatibility and dispersion. Carbohydr Polym 102:369–375 Aulin C (2009) Novel oil resistant cellulosic materials. Doctoral Thesis, KTH Royal Institute, Stockholm Aulin C, Ahola S, Josefsson P, Nishino T, Hirose Y, Österberg M, Wagberg L (2009) Nanoscale cellulose films with different crystallinities and mesostructures-their surface properties and interaction with water. Langmuir 25:7675–7685 Aulin C, Johansson E, Wågberg L, Lindström T (2010a) Self-organized films from cellulose I nanofibrils using the layer-by-layer technique. Biomacromolecules 11(4):872–882

Nanocellulose in Paper and Board Coating

277

Aulin C, Gallstedt M, Lindström T (2010b) Oxygen and oil barrier properties of microfibrillated cellulose films and coatings. Cellulose 17:559–574 Ávila Ramírez JA, Fortunati E, Kenny JM, Torre L, Foresti ML (2017) Simple citric acid-catalyzed surface esterification of cellulose nanocrystals. Carbohydr Polym 157:1358–1364 Ayoub A, Bliard C (2003) Cationisation of glycerol plasticised wheat starch under microhydric molten conditions. Starch 55(7):297–303 Ayouba A, Berzin F, Tighzert L, Bliard C (2004) Study of the thermoplastic wheat starch cationisation reaction under molten condition. Starch 56(11):513–519 Bäckström M, Bolivar S, Paltakari J (2012) Effect of ionic form on fibrillation and the development of the fibre network strength during the refining of the kraft pulps. OPAP 73:57–65 Bajpai P (2018) Chapter 2: Paper and its properties. In: Bajpai P (ed) Biermann’s handbook of pulp and paper, Paper and board making, vol 2. Elsevier, Amsterdam, Holland, p 60 Balea A, Blanco A, Monte MC, Merayo N, Negro C (2016a) Effect of bleached Eucalyptus and Pine cellulose nanofibers on the physico-mechanical properties of cartonboard. Bioresources 11(4):8123–8138 Balea A, Merayo N, Fuente E, Delgado-Aguilar M, Mutje P, Blanco A, Negro C (2016b) Valorization of corn stalk by the production of cellulose nanofibers to improve recycled paper properties. Bioresources 11(2):3416–3431 Balea A, Merayo N, Seara M, Fuente E, Blanco A, Negro C (2016c) Effect of CNF from organosolv corn stalk pulp on retention and drainage during papermaking. Cellul Chem Technol 50(3–4):377–383 Balea A, Sanchez-Salvador JL, Monte MC, Merayo N, Negro C, Blanco A (2019) In situ production and application of cellulose nanofibers to improve recycled paper production. Molecules 24(9):1800 Balea A, Campano C, Negro C, Blanco A (2020) Industrial application of nanocelluloses in solutions, and market perspectives. Molecules 25:526–556 Barbash VA, Yashchenko OV (2020) Preparation and application of nanocellulose from non wood plants to improve the quality of paper and cardboard. Appl Nanosci 10:2705–2716 Barbey R, Lavanant L, Paripovic D, Schuwer N, Sugnaux C, Tugulu S, Klok HA (2009) Polymer brushes via surface-initiated controlled radical polymerization: synthesis, characterization, properties, and applications. Chem Rev 109:5437–5527 Beaumont M, Winklehner S, Veigel S, Mundigler N, Gindl-Altmutter W, Potthast A, Rosenau T (2020) Wet esterification of never-dried cellulose: a simple process to surface-acetylated cellulose nanofibers. Green Chem 22:5605–5609 Beck S, Bouchard J, Berry R (2011) Controlling the reflection wavelength of iridescent solid films of nanocrystalline cellulose. Biomacromolecules 12:167–172 Beck S, Bouchard J, Berry R (2012) Dispersibility in water of dried nanocrystalline cellulose. Biomacromolecules 13:1486–1494 Bendahou D, Bendahou A, Seantier B, Grohens Y, Kaddami H (2015) Nano-fibrillated cellulose-­ zeolites based new hybrid composites aerogels with super thermal insulating properties. Ind Crop Prod 65:374–382 Beneventi D, Chaussy D, Curtil D, Zolin L, Gerbaldi C, Penazzi N (2014) Highly porous paper loading with microfibrillated cellulose by spray coating on wet substrates. Ind Eng Chem Res 53:10982–10989 Benítez AJ, Torres-Rendon J, Poutanen M, Walther A (2013) Humidity and multiscale structure govern mechanical properties and deformation modes in films of native cellulose nanofibrils. Biomacromolecules 14:4497–4506 Berlioz S, Molinaboisseau S, Nishiyama Y, Heux L (2009) Gas-phase surface esterification of cellulose microfibrils and whiskers. Biomacromolecules 10(8):2144–2151 Berrocal MM, Rodriguez J, Hernández M, Pérez MI, Roncero MB, Vidal T, Ball AS, Arias ME (2004) The analysis of handsheets from wheat straw following solid substrate fermentation by Streptomyces cyaneus and soda cooking treatment. Bioresour Technol 94(1):27–31

278

A. Tozluoglu et al.

Besbes I, Alila S, Boufi S (2011) Nanofibrillated cellulose from TEMPO-oxidized eucalyptus fibres: Effect of the carboxyl content. Carbohydrate Polymers 84(3):975-983 Bharimalla A, Deshmukh S, Patil PG, Nadanathangam V (2017) Micro/nano-fibrillated cellulose from cotton linters as strength additive in unbleached kraft paper: experimental, semi-­ empirical, and mechanistic studies. Bioresources 12(3):5682–5696 Bhattacharjee S (2016) DLS and zeta potential—what they are and what they are not? J Control Release 235:337–351 Biricik Y, Atik C (2012) Effect of cellulase treatment of long fiber fraction on strength properties of recycled corrugated medium. Afr J Biotechnol 11(58):12199–12205 Biyani MV, Foster EJ, Weder C (2013) Light-healable supramolecular nanocomposites based on modified cellulose nanocrystals. ACS Macro Lett 2:236–240 Blilid S, Katir N, El Haskouri J, Lahcini M, Royer S, El Kadib A (2019) Phosphorylated micro- vs nano-cellulose: a comparative study on their surface functionalisation, growth of titanium-oxo-­ phosphate clusters and removal of chemical pollutants. New J Chem 43(39):15555 Blilid S, Kędzierska M, Miłowska K, Wrońska N, El Achaby M, Katir N, Belamie E, Alonso B, Lisowska K, Lahcini M, Bryszewska M, El Kadib A (2020) Phosphorylated micro- and nanocellulose-­filled chitosan nanocomposites as fully sustainable, biologically active bioplastics. ACS Sustain Chem Eng 8(50):18354–18365 Boissard Y (2017) MFC for paper surface treatment. Master of Science Thesis. Luleå University of Technology, Luleå, Sweden Boluk Y, Lahiji R, Zhao L, McDermott MT (2011) Suspension viscosities and shape parameter of cellulose nanocrystals (CNC), Colloids Surf A Physicochem Eng Asp. 377(1–3):297–303 Boufi S, González I, Delgado-Aguilar M, Tarrès Q, Pèlach MÀ, Mutjé P (2016) Nanofibrillated cellulose as an additive in papermaking process: a review. Carbohydr Polym 154:151–166 Boujemaoui A, Mazières S, Malmström E, Destarac M, Carlmark A (2016) SIRAFT/MADIX polymerization of vinyl acetate on cellulose nanocrystals for nanocomposite applications. Polymer 99:240–249 Brand J, Pecastaings G, Sebe G (2017) A versatile method for the surface tailoring of cellulose nanocrystal building blocks by acylation with functional vinyl esters. Carbohydr Polym 169:189–197 Braun B, Dorgan JR (2009) Single-step method for the isolation and surface functionalization of cellulosic nanowhiskers. Biomacromolecules 10:334–341 Braun B, Dorgan JR, Hollingsworth LO (2012) Supra-molecularecobionanocomposites based on polylactide and cellulosic nanowhiskers:synthesis and properties. Biomacromolecules 13(7):2013–2019 Braunecker WA, Matyjaszewski K (2007) Controlled/living radical polymerization: features, developments, and perspectives. Prog Polym Sci 32:93–146 Britt KW, Unbehend JE, Shridharan R (1986) Observations on water removal in papermaking. TAPPI J 69:76–79 Brodin FW, Eriksen Ø (2015) Preparation of individualised lignocellulose microfibrils based on thermomechanical pulp and their effect on paper properties. Nord Pulp Pap Res J 30:443–451 Brodin FW, Gregersen ØW, Syverud K (2014) Cellulose nanofbrils: challenges and possibilities as a paper additive or coating material—a review. Nord Pulp Pap Res J 29:156–166 Camarero Espinosa S, Kuhnt T, Foster EJ, Weder C (2013) Isolation of thermally stable cellulose nanocrystals by phosphoric acid hydrolysis. Biomacromolecules 14:1223–1230 Campano C, Merayo N, Balea A, Tarrés Q, Delgado-Aguilar M, Mutjé P, Negro C, Blanco A (2018) Mechanical and chemical dispersion of nanocelluloses to improve their reinforcing efect on recycled paper. Cellulose 25:269–280 Candan Z, Gardner DJ, Shaler SM (2016) Dynamic mechanical thermal analysis (DMTA) of cellulose nanofibril/nanoclay/pMDI nanocomposites. Compos Part B 90:126–132 Candan Z, Tozluoglu A, Gonultas O, Yildirim M, Fidan H, Alma MH, Salan T (2022) Nanocellulose: sustainable biomaterial for developing novel adhesives and composites. In: Industrial applications of nanocellulose and its nanocomposites. Elsevier, pp 49–137

Nanocellulose in Paper and Board Coating

279

Cao X, Habibi Y, Lucia LA (2009) One-pot polymerization, surface grafting, and processing of waterborne polyurethane-cellulose nanocrystal nanocomposites. J Mater Chem 19(38):7137–7145 Cao SL, Li XH, Lou WY, Zong MH (2014) Preparation of a novel magnetic cellulose nanocrystal and its efficient use for enzyme immobilization. J Mater Chem B 2(34):5522–5530 Carlmark A, Malmström E (2002) Atom transfer radical polymerization from cellulose fibers at ambient temperature. J Am Chem Soc 124:900–901 Carlsson DO, Nyström G, Zhou Q, Berglund LA, Nyholm L, Strømme M (2012) Electroactive nanofibrillated cellulose aerogel composites with tunablestructural and electrochemical properties. J Mater Chem 22:19014–19024 Cataldi A, Corcione CE, Frigione M, Pegoretti A (2017) Photocurable resin/nanocellulose composite coatings for wood protection. Prog Org Coat 106:128–136 Celebi H, Ilgar M, Seyhan AT (2021) Evaluation of the effect of isocyanate modification on the thermal and rheological properties of poly(epsilon-caprolactone)/cellulose composites. Polym Bull Cervin NT, Aulin C, Larsson PT, Waagberg L (2011) Ultra porous nanocellulose aerogels as separation medium for mixtures of oil/water liquids. Cellulose 19:401–410 Cervin NT, Andersson L, Ng JBS, Olin P, Bergström L, Wågberg L (2013) Lightweight and strong cellulose materials made from aqueous foams stabilized by nanofibrillated cellulose. Biomacromolecules 14(2):503–511 Cervin NT, Johansson E, Larsson PA, Wågberg L (2016) Strong, water-durable, and wet-­ resilient cellulose nanofibril-stabilized foams from oven drying. ACS Appl Mater Interfaces 8(18):11682–11689 Cetin NS, Tingaut P, Ozmen N, Henry N, Harper D, Dadmun M, Sèbe G (2009) Acetylation of cellulose nanowhiskers with vinyl acetate under moderate conditions. Macromol Biosci 9(10):997–1003 Charani PR, Dehghani-Firouzabadi M, Afra E, Blademo A, Naderi A, Lindstrom T (2013) Production of microfibrillated cellulose from unbleached kraft pulp of Kenaf and Scotch pine and its effect on the properties of hardwood kraft: microfibrillated cellulose paper. Cellulose 20(5):2559–2567 Chauve G, Bras J (2014) Chapter 14  – Industrial point of view of nanocellulose materials and their possible applications. In: Oksman K, Mathew AP, Bismarck A, Rojas O, Sain M (eds) Handbook of green materials. World Scientific Publishing Co Pte Ltd, Singapore, pp 233–252 Chen G, Dufresne A, Huang J, Chang PR (2009) A novel thermoformable bionanocomposite based on cellulose nanocrystal-graft-poly(epsilon-caprolactone). Macromol Mater Eng 294(1):59–67 Chen W, Li Q, Wang Y, Yi X, Zeng J, Yu H, Liu Y, Li J (2014) Comparative study of aerogels obtained from differently prepared nanocellulose fibers. ChemSusChem 7(1):154–161 Cheng M, Qin Z, Liu Y, Qin Y, Li T, Chen L, Zhu M (2014) Efficient extraction of carboxylated spherical cellulose nanocrystals with narrow distribution through hydrolysis of lyocell fibers by using ammonium persulfate as an oxidant. J Mater Chem A2(1):251–258 Cheng M, Qin Z, Chen Y, Liu J, Ren Z (2017) Facile one-step extraction and oxidative carboxylation of cellulose nanocrystals through hydrothermal reaction by using mixed inorganic acids. Cellulose 24:3243–3254 Cheng HN, Kilgore K, Ford C, Fortier C, Dowd MK, He Z (2019) Cottonseed protein-based wood adhesive reinforced with nanocellulose. J Adhes Sci Technol 33:1357–1368 Chin KM, Ting SS, Ong HL, Omar M (2018) Surface functionalized nanocellulose as a veritable inclusionary material in contemporary bioinspired applications: a review. J Appl Polym Sci 135:46065 Chinga-Carrasco G (2014) Nanocellulose as a biomaterial—characteristics and bio applications. In: 5th recent advances in cellulose nanotechnology research seminar Cobut A, Sehaqui H, Berglund LA (2014) Cellulose nanocomposites by meltcompounding of TEMPO-treated wood fibers in thermoplastic starch matrix. Bioresources 9(2):3276–3289

280

A. Tozluoglu et al.

Cranston ED, Gray DG (2006) Morphological and optical characterization of polyelectrolyte multilayers incorporating nanocrystalline cellulose. Biomacromolecules 7:2522–2530 Culsum NTU, Melinda C, Leman I, Wibowo A, Budhi YW (2021) Isolation and characterization of cellulose nanocrystals (CNCs) from industrial denim waste using ammonium persulfate. Mater Today Commun 26:101817 Cunha AG, Zhou Q, Larsson PT, Berglund LA (2014) Topochemical acetylation of cellulose nanopaper structures for biocomposites: mechanisms for reduced water vapour sorption. Cellulose 21:2773–2787 Curvelo A, Menezes A, Dufresne A, Siqueira G (2009) Extrusion and characterization of functionalized cellulose whiskers reinforced polyethylene nanocomposites. Polymer 50(19):4552–4563 Dai L, Long Z, Chen J, An X, Cheng D, Khan A, Ni Y (2017) Robust guar gum/cellulose nanofibrils multilayer films with good barrier properties. ACS Appl Mater Interfaces 9(6):5477–5485 Dasgupta S (1994) Mechanism of paper tensile-strength development due to pulp beating. TAPPI J 77(6):158–164 Daud JB, Lee KY (2017) Chapter – 3 Surface modification of nanocellulose. In: Kargarzadeh H, Ahmad I, Thomas S, Dufresne A (eds) Handbook of nanocellulose and cellulose nanocomposites, 1st edn. Wiley-VCH Verlag GmbH & Co. KGaA Davis NJ, Flitsch SL (1993) Selective oxidation of monosaccharide derivatives touronic acids. Tetrahedron Lett 34(7):1181–1184 de Nooy AEJ, Besemer AC, van Bekkum H (1994) Highly selective TEMPO mediated oxidation of primary alcohol groups in polysaccharides. Recueil des Travaux Chimiques des Pays Bas 113(3):165–166 de Nooy AEJ, Besemer AC, van Bekkum H, van Dijk JAPP, Smit JAM (1996) TEMPO-mediated oxidation of pullulan and influence of ionic strength and linear charge density on the dimensions of the obtained polyelectrolyte chains. Macromolecules 29:6541–6547 Deepa B, Pillai SS, Pothan LA, Thomas S (2013) Chapter – 19 Mechanical properties of cellulose-­ based bionanocomposites. In: Dufresne A, Thomas S, Pothen LA (eds) Biopolymer nanocomposites. Wiley, New York Delgado-Aguilar M, González I, Pélach MA, De La Fuente E, Negro C (2015) Improvement of deinked old newspaper/old magazine pulp suspensions by means of nanofibrillated cellulose addition. Cellulose 22:789–802 Deville S (2013) Ice-templating, freeze casting: beyond materials processing. J Mater Res., Cambridge University Press (CUP) 28(17):2202–2219 Dlouhá J, Suryanegara L, Yano H (2012) The role of cellulose nanofibres in supercritical foaming of polylactic acid and their effect on the foam morphology. Soft Matter 8:8704–8713 Dong XM, Kimura T, Revol JF, Gray DG (1996) Effects of ionic strength on the phase separation of suspensions of cellulose crystallites. Langmuir 12:2076–2082 Dong F, Yan M, Jin C, Li S (2017) Characterization of type-II acetylated cellulose nanocrystals with various degree of substitution and its compatibility in PLA films. Polymers 9(8):346 Du H, Liu W, Zhang M, Si C, Zhang X, Li B (2019) Cellulose nanocrystals and cellulose nanofibrils based hydrogels for biomedical applications. Carbohydr Polym 209:130–144 Dufresne A (2013) Nanocellulose: a new ageless bionanomaterial. Mater Today 16:220–227 Dufresne A (2017) Nanocellulose: from nature to high performance tailored material. In: Nanocellulose. De Gruyter, Berlin/Boston Dufresne A, Cavaille JY, Vignon MR (1997) Mechanical behavior of sheets prepared from sugar beet cellulose microfibrils. J Appl Polym Sci 64(6):1185–1194 Durmaz E (2021) Ayçiçeği Saplarından Bazı Nanoselüloz Türevlerinin Üretimi, Karakterizasyonu ve Farklı Uygulama Alanlarında Değerlendirilmesi, Doktora Tezi, Kastamonu Üniversitesi, Fen Bilimleri Enstitüsü, Kastamonu Dury-Brun C, Jury V, Guillard V, Desobry S, Voilley A, Chalier P (2006) Water barrier properties of treated-papers and application to sponge cake storage. Food Res Int 39:1002–1011 Earle MJ, Seddon KR (2000) Ionic liquids. Green solvents for the future. Pure Appl Chem 72(7):1391–1398

Nanocellulose in Paper and Board Coating

281

Ehman NV, Felissia FE, Tarrés Q, Vallejos ME, Delgado-Aguilar M, Mutjé P, Area MC (2020) Effect of nanofiber addition on the physical–mechanical properties of chemimechanical pulp handsheets for packaging. Cellulose 27:10811–10823 Eriksen Ø, Syverud K, Gregersen Ø (2008) The use of microfibrillated cellulose produced from kraft pulp as strength enhancer in TMP paper. Nord Pulp Pap Res J 23(3):299–304 Espino-Pérez E, Gilbert RG, Domenek S, Brochier-Salon MC, Belgacem MN, Bras J (2016) Nanocomposites with functionalised polysaccharide nanocrystals through aqueous free radical polymerisation promoted by ozonolysis. Carbohydr Polym 135:256–266 Espinosa E, Dominguez-Robles J, Sanchez R, Tarres Q, Rodriguez A (2017) The effect of pre-­ treatment on the production of lignocellulosic nanofibers and their application as a reinforcing agent in paper. Cellulose 24:2605–2618 Eyholzer C, Bordeanu N, Lopez-Suevos F, Rentsch D, Zimmermann T, Oksman K (2010) Preparation and characterization of water-redispersible nanofibrillated cellulose in powder form. Cellulose 17:19–30 Eyholzer C, Tingaut P, Zimmermann T, Oksman K (2012) Dispersion and reinforcing potential of carboxymethylated nanofibrillated cellulose powders modified with 1-hexanol in extruded poly (lactic acid)(PLA) composites. J Polym Environ 20:1052–1062 Eyley S, Thielemans W (2014) Surface modification of cellulose nanocrystals. Nanoscale 6:7764–7779 Fantin M, Isse AA, Venzo A, Gennaro A, Matyjaszewski K (2016) Atom transfer radical polymerization of methacrylic acid: a won challenge. J Am Chem Soc 138(23):7216–7219 Fengel D, Wegener G (1989) Cellulose, vol 4. Walter de Gruyter, Berlin/New York, pp 66–69 Fidan H, Tozluoğlu A, Tutuş A, Arslan R, Sertkaya S, Poyraz B, Küçük SD, Sözbir T, Yemşen B, Gücüş MO (2021) Reinforcement potential of modified nanofibrillated cellulose in recycled paper production. Bioresources 16(1):911–941 Foster EJ, Moon RJ, Agarwal UP, Bortner MJ, Bras J, Camarero-Espinosa S, Chan JK, Clift MJD, Cranston ED, Eichhron SJ, Fox DM, Hamad WY, Heux L, Jean B, Korey M, Nieh W, Ong KJ, Reid MS, Renneckar S, Roberts R, Shatkin JA, Simonsen J, Stinson-Bagby K, Wanasekara N, Youngblodd J (2018) Current characterization methods for cellulose nanomaterials. Chem Soc Rev 47(8):2609–2679 French AD (2014) Idealized powder diffraction patterns for cellulose polymorphs. Cellulose 21:885–896 Frka-Petesic B, Sugiyama J, Kimura S, Chanzy H, Maret G (2015) Negative diamagnetic anisotropy and birefringence of cellulose nanocrystals. Macromolecules 48(24):8844–8857 Fujisawa S, Okita Y, Fukuzumi H, Saito T, Isogai A (2011) Preparation and characterization of TEMPO-oxidized cellulose nanofibril films with free carboxyl groups. Carbohydr Polym 84(1):579–583 Fukuzumi H, Saito T, Iwata T, Kumamoto Y, Isogai A (2009) Transparent and high gas barrier films of cellulose nanofibers prepared by TEMPO-mediated oxidation. Biomacromolecules 10(1):162–165 Gadhave RV, Dhawale PV, Sorate CS (2021) Surface modification of cellulose with silanes for adhesive application: review. Open J Polym Chem 11:11–30 Gan L, Liao J, Lin N, Hu C, Wang H, Huang J (2017) Focus on gradientwise control of the surface acetylation of cellulose nanocrystals to optimize mechanical reinforcement for hydrophobic polyester-based nanocomposites. ACS Omega 2(8):4725–4736 García A, Gandini A, Labidi J, Belgacem N, Bras J (2016) Industrial and crop wastes: a new source for nanocellulose biorefinery. Ind Crop Prod 93:26–38 Garcia-Valdez O, Brescacin T, Arredondo J, Bouchard J, Jessop PG, Champagne P, Cunningham MF (2017) Grafting CO2-responsive polymers from cellulose nanocrystals via nitroxide-­ mediated polymerisation. Polym Chem 8:4124–4131 Gardner DJ, Oporto GS, Mills R, Samir MASA (2008) Adhesion and surface issues in cellulose and nanocellulose. J Adhes Sci Technol 22:545–567

282

A. Tozluoglu et al.

Garvey CJ, Parker IH, Simon GP (2005) On the interpretation of X-ray diffraction powder patterns in terms of the nanostructure of cellulose I fibres. Macromol Chem Phys 206(15):1568–1575 Gawryla MD, van den Berg O, Weder C, Schiraldi DA (2009) Clay aerogel/cellulosewhisker nanocomposites: a nanoscale wattle and daub. J Mater Chem 19:2118–2124 Ghanadpour M, Carosio F, Larsson PT, Wågberg L (2015) Phosphorylated cellulose nanofibrils: a renewable nanomaterial for the preparation of intrinsically flame-retardant materials. Biomacromolecules 16:3399–3410 Ghasemian A, Ghaffari M, Ashori A (2012) Strength-enhancing effect of cationic starch on mixed recycled and virgin pulps. Carbohydr Polym 87:1269–1274 Gibson LJ, Ashby MF (1999) Cellular solids: structure and properties. Cambridge University Press Goffin AL, Raquez JM, Duquesne E, Siqueira G, Habibi Y, Dufresne A, Dubois P (2011) From interfacial ring-opening polymerization to melt processing of cellulose nanowhisker-filled polylactide-based nanocomposites. Biomacromolecules 12(7):2456–2465 Goffin AL, Habibi Y, Raquez JM, Dubois P (2012) Polyester-grafted cellulose nanowhiskers: a new approach for tuning the microstructure of immiscible polyester blends. ACS Appl Mater Interfaces 4(7):3364–3371 González I, Boufi S, Pèlach MA, Alcalá M, Vilaseca F, Mutjé P (2012) Nanofibrillated cellulose as paper additive in eucalyptus pulps. BioRes 7(4):5167–5180 González I, Vilaseca F, Alcalá M, Pélach MA, Boufi S, Mutjè P (2013) Effect of the combination of biobeating and CNF on the physico-mechanical properties of paper. Cellulose 20:1425–1435 Gordeyeva KS, Fall AB, Hall S, Wicklein B, Bergström L (2016) Stabilizing nanocellulose-­ nonionic surfactant composite foams by delayed Ca-induced gelation. J Colloid Interface Sci 472:44–51 Goussé C, Chanzy H, Excoffier G, Soubeyrand L, Fleury E (2002) Stable suspensions of partially silylated cellulose whiskers dispersed in organic solvents. Polymer 43(9):2645–2651 Goussé C, Chanzy H, Cerrada ML, Fleury E (2004) Surface silylation of cellulose microfibrils: preparation and rheological properties. Polymer 45(5):1569–1575 Granström M (2009) Cellulose derivatives: synthesis, properties and applications. Master Thesis, University of Helsinki, Finland Gray DG (2016) Recent advances in chiral nematic structure and iridescent color of cellulose nanocrystal films. Nano 6(11):213 Grunert M, Winter WT (2002) Nanocomposites of cellulose acetate butyrate reinforced with cellulose nanocrystals. J Polym Environ 10:27–30 Habibi Y (2014) Key advances in the chemical modification of nanocelluloses. Chem Soc Rev 43:1519–1542 Habibi Y, Vignon MR (2008) Optimization of cellouronic acid synthesis by TEMPO-mediated oxidation of cellulose III from sugar beet pulp. Cellulose 15:177–185 Habibi Y, Lucia LA, Rojas OJ (2010) Cellulose nanocrystals chemistry, self assembly, and applications. Chem Rev 110:3479–3500 Hadilam MM, Afra E, Yousefi H (2013) Effect of cellulose nanofibers on the properties of bagasse paper. J For Wood Prod (Iran J Nat Resour) 66(3):351–366 Hamada H, Beckvermit J, Busfield DW (2010) Nanofibrillated cellulose with fine clay as a coating agent to improve print quality. TAPPI Coting Conference Hamada H, Tahara K, Uchida A (2012) The effects of nano-fibrillated cellulose as a coating agent for screen printing. 12th TAPPI Advanced Coating Fundamentals Symposium Hämäläinen P, Hallbäck N, Gåård A, Lestelius M (2017) On the determination of transverse shear properties of paper using the short span compression test. Mech Mater 107:22–30 Hamedi M, Karabulut E, Marais A, Herland A, Nyström G, Wågberg L (2013) Nanocellulose aerogels functionalized by rapid layer-by-layer assembly for high charge storage and beyond. Angew Chem 125(46):12260–12264 Hanif Z, Jeon H, Tran TH, Jegal J, Park SA, Kim SM, Park J, Hwang SY, Oh DX (2017) Butanol-­ mediated oven-drying of nanocellulose with enhanced dehydration rate and aqueous re-­ dispersion. J Polym Res 25:191

Nanocellulose in Paper and Board Coating

283

Hansson S, Östmark E, Carlmark A, Malmström E (2009) ARGET ATRP for versatile grafting of cellulose using various monomers. ACS Appl Mater Interfaces 1(11):2651–2659 Hansson S, Trouillet V, Tischer T, Goldmann AS, Carlmark A, Barner-Kowollik C, Malmström E (2013) Grafting efficiency of synthetic polymers onto biomaterials: a comparative study of grafting-from versus grafting-to. Biomacromolecules 14(1):64–74 Hansson S, Carlmark A, Malmström E, Fogelström L (2015) Toward industrial grafting of cellulosic substrates via ARGET ATRP. J Appl Polym Sci 132(6):41434 Hasani M, Cranston ED, Westman G, Gray DG (2008) Cationic surface functionalization of cellulose nanocrystals. Soft Matter 4:2238–2244 Hassan EA, Hassan ML, Abou-zeid RE, El-Wakil NA (2016) Novel nanofibrillated cellulose/ chitosan nanoparticles nanocomposites films and their use for paper coating. Ind Crop Prod 93:219–222 Hayase G, Kanamori K, Abe K, Yano H, Maeno A, Kaji H, Nakanishi N (2014) Polymethylsilsesquioxane–cellulose nanofiber biocomposite aerogels withhigh thermal insulation, bendability, and superhydrophobicity. ACS Appl Mater Interfaces 6(12):9466–9471 He M, Yang G, Cho B, Lee YK, Won J (2017) Effects of addition method and fibrillation degree of cellulose nanofibrils on furnish drainability and paper properties. Cellulose 24:5657–5669 Henriksson M, Henriksson G, Berglund LA, Lindström T (2007) An environmentally friendly method for enzyme-assisted preparation of microfibrillated cellulose (MFC) nanofibers. Eur Polym J 43(8):3434–3441 Henriksson M, Berglund LA, Isaksson P, Lindström T, Nishino T (2008) Cellulose nanopaper structures of high toughness. Biomacromolecules 9:1579–1585 Herrick FW, Casebier RL, Hamilton JK, Sandberg KR (1983) Microfibrillated cellulose: morphology and accessibility. J Appl Polym Sci Appl Polym Symp 37:797–813 Hietala M, Ämmälä A, Silvennoinen J, Liimatainen H (2016) Fluting medium strengthened by periodate–chlorite oxidized nanofibrillated celluloses. Cellulose 23:427–437 Hirota M, Furihata K, Saito T, Kawada T, Isogai A (2010) Glucose/glucuronic acid alternating copolysaccharide prepared from TEMPO-oxidized native celluloses by surface-peeling. Angew Chem Int 49:7670–7672 Ho TT, Zimmermann T, Hauert R, Caseri W (2011) Preparation and characterization of cationic nanofibrillated cellulose from etherification and high-shear disintegration processes. Cellulose 18(6):1391–1406 Ho T, Abe K, Zimmermann T, Yano H (2015) Nanofibrillation of pulp fibersby twin-screw extrusion. Cellulose 22:421–433 Hollertz R, Durán VL, Larsson PA, Wågberg L (2017) Chemically modifed cellulose micro- and nanofbrils as paper-strength additives. Cellulose 24(9):3883–3899 Houde M, Martin JW, Letcher RJ, Solomon KR, Muir DCG (2006) Biological monitoring of polyfluoroalkyl substances: a review. Environ Sci Technol 40:3463–3473 Hu C, Zhao Y, Li K, Zhu YJ, Gleisner R (2015) Optimizing cellulose fibrillation for the production of cellulose nanofibrils by a disk grinder. Holzforschung 69(8):993–1000 Huang J, Dufresne A, Lin N (2019) Nanocellulose: from fundamentals to advanced materials. Willey-WCH, Weinheim, Germany Hubbe M, Heitmann J (2007) Review of factors affecting the release of water from cellulosic fibers during paper manufacture. Bioresources 2(3):500–533 Hubbe MA, Rojas OJ, Lucia LA, Sain M (2008) Cellulosic nanocomposites: a review. Bioresources 3(3):929–980 Hubbe M, Ferrer A, Tyagi P, Yin Y, Salas C, Pal L, Rojas OJ (2017) Nanocellulose in in thin flms, coatings, and plies for packag- ing applications: a review. Bioresources 12:2143–2233 Hult EL, Lotti M, Lenes M (2010) Efficient approach to high barrier packaging using microfibrillar cellulose and shellac. Cellulose 15:575–586 Ifuku S, Nogi M, Abe K, Handa K, Nakatsubo F, Yano H (2007) Surface modification of bacterial cellulose nanofibers for property enhancement of optically transparent composites-dependence on acetyl-group DS. Biomacromolecules 8:1973–1978

284

A. Tozluoglu et al.

Ifuku S, Tsuji M, Morimoto M, Saimoto H, Yano H (2009) Synthesis of silver nanoparticles templated by TEMPO-mediated oxidized bacterial cellulose nanofibers. Biomacromolecules 10(9):2714–2717 Ilies DC, Zlatev Z, Ilies A, Zharas B, Pantea E, Hodor N, Indrie L, Turza A, Taghiyari HR, Caciora T, Costea M, Safarov B, Lucian BT (2022) Interdisciplinary research to advance digital imagery and natural compounds for eco-cleaning and for preserving textile cultural heritage. Sensors 22:4442. https://doi.org/10.3390/s22124442 Inagaki N, Nakamura S, Asai H, Katsuura K (1976) Phosphorylation of cellulose with phosphorous acid and thermal degradation of the product. J Appl Polym Sci 20:2829–2836 Ishida O, Kim DY, Kuga S, Nishiyama Y, Brown RM (2004) Microfibrillar carbon from native cellulose. Cellulose 11:475–480 Islam MT, Alam MM, Zoccola M (2013) Review on modification of Nanocellulose for application in composites. Int J Innov Res Sci Eng Technol 2(10):5444–5451 ISO/TS 20477 (2017) Nanotechnologies  – standard terms and their definition for cellulose nanomaterial Isogai A (2013) Wood nanocelluloses: fundamentals and applications as new bio-based nanomaterials. J Wood Sci 59:449–459 Isogai A, Saito T, Fukuzumi H (2011) TEMPO-oxidized cellulose nanofibers. Nanoscale 3:71–85 Isogai A, Hänninen T, Fujisawa S, Saito T (2018) Review: catalytic oxidation of cellulose with nitroxyl radicals under aqueous conditions. Prog Polym Sci 86:122–148 Iwamoto S, Nakagaito AN, Yano H, Nogi M (2005) Optically transparent composites reinforced with plant fiber-based nanofibers. Appl Phys A 81:1109–1112 Iwamoto S, Nakagaito AN, Yano H (2007) Nano-fibrillation of pulp fibers for the processing of transparent nanocomposites. Appl Phys A 89:461–466 Jang JH, Lee SH, Endo T, Kim NH (2013) Characteristics of microfibrillated cellulosic fibers and paper sheets from Korean white pine. Wood Sci Technol 47:925–937 Jankauskaitė V, Balčiūnaitienė A, Alexandrova R, Buškuvienė N, Žukienė K (2020) Effect of cellulose microfiber silylation procedures on the properties and antibacterial activity of polydimethylsiloxane. Coatings 10(6):567 Jasim A, Ullah MW, Shi Z, Lin X, Yang G (2017) Fabrication of bacterial cellulose/polyaniline/ single-walled carbon nanotubes membrane for potential application as biosensor. Carbohydr Polym 163:62–69 Jiang F, Hsieh YL (2013) Chemically and mechanically isolated nanocellulose and their self-­ assembled structures. Carbohydr Polym 95(1):32–40 Jonoobi M, Harun J, Mathew AP, Hussein MZB, Oksman K (2009) Preparation of cellulose nanofibers with hydrophobic surface characteristics. Cellulose 17(2):299–307 Jonoobi M, Oladi R, Davoudpour Y, Oksman K, Dufresne A, Hamzeh Y, Davoodi R (2015) Different preparation methods and properties of nanostructured cellulose from various natural resources and residues: a review. Cellulose 22:935–969 Joseleau JP, Chevalier-Billosta V, Ruel K (2012) Interaction between microfibrillar cellulose fines and fibers: influence on pulp qualities and papersheet properties. Cellulose 19:769–777 Kaboorani A, Riedl B, Blanchet P, Fellin M, Hosseinaei O, Wang S (2012) Nanocrystalline cellulose (NCC): a renewable nano-material for polyvinyl acetate (PVA) adhesive. Eur Polym J 48:1829–1837 Kalia S, Boufi S, Celli A, Kango S (2014) Nanofibrillated cellulose: surface modification and potential applications. Colloid Polym Sci 292:5–31 Kallel F, Bettaieb F, Khiari R, García A, Bras J, Chaabouni SE (2016) Isolation and structural characterization of cellulose nanocrystals extracted from garlic straw residues. Ind Crop Prod 87:287–296 Kan KHM, Li J, Wijesekera K, Cranston ED (2013) Polymer-grafted cellulose nanocrystals as pH-­ responsive reversible flocculants. Biomacromolecules 14(9):3130–3139 Kang T, Paulapuro H (2006) Effect of external fibrillation onpaper strength. Pulp Paper Can 107(7/8):51–54

Nanocellulose in Paper and Board Coating

285

Kargarzadeh H (2017) Handbook of nanocellulose and cellulose nanocomposites. Wiley-VCH Verlag GmbH & Co, KGaA, Weinheim Kargarzadeh H, Huang J, Lin N, Ahmad I, Mariano M, Dufresne A, Thomas S, Gałęski A (2018) Recent developments in nanocellulose-based biodegradablepolymers, thermoplastic polymers, and porous nanocomposites. Prog Polym Sci 87:197–227 Kasiri N, Fathi M (2018) Production of cellulose nanocrystals from pistachio shells and theirapplication for stabilizing Pickering emulsions. Int J Biol Macromol 106:1023–1031 Kasmani J, Samariha A (2019) Effect of nano-cellulose on the improvement of the properties of paper newspaper produced from chemi-mechanical pulping. Bioresources 14(4):8935–8949 Kedzior SA, Graham L, Moorlag C, Dooley BM, Cranston ED (2016) Poly(methyl methacrylate)grafted cellulose nanocrystals: one-step synthesis, nanocomposite preparation, and characterization. Can J Chem Eng 94(5):811–822 Kedzior SA, Zoppe JO, Berry RM, Cranston ED (2018) Recent advances and an industrial perspective of cellulose nanocrystal functionalization through polymer grafting. Curr Opinion Solid State Mater Sci 23(2):74–91 Kekäläinen K, Liimatainen H, Illikainen M, Maloney TC, Niinimäki J (2014a) The role of hornification in the disintegration behaviour of TEMPO-oxidized bleached hardwood fibres in a high-shear homogenizer. Cellulose 21(3):1163–1174 Kekäläinen K, Liimatainen H, Niinimäki J (2014b) Disintegration of periodate–chlorite oxidized hardwood pulp fibres to cellulose microfibrils: kinetics and charge threshold. Cellulose 21:3691–3700 Kekäläinen K, Liimatainen H, Biale F, Niinimäki J (2015) Nanofibrillation of TEMPO-oxidized bleached hardwood kraft cellulose at high solids content. Holzforschung 69(9):1077–1088 Khanjanzadeh H, Behrooz R, Bahramifar N, GindlAltmutter W, Bacher M, Edler M, Griesser T (2018) Surface chemical functionalization of cellulose nanocrystals by 3-­aminopropyltriethoxysilane. Int J Biol Macromol 106:1288–1296 Khiari R, Mauret E, Belgacem MN, Mhemmi F (2011) Tunisian date palm rachis used as an alternative source of fibres for papermaking applications. Bioresources 6:265–281 Kim UJ, Kuga S (2001) Ion-exchange chromatography by dicarboxyl cellulosegel. J Chromatogr A919(1):29–37 Kim HJ, Park S, Kim SH, Kim JH, Yu H, Kim HJ, Yang YH, Kan E, Kim YH, Lee SH (2015a) Biocompatible cellulose nanocrystals as supports to immobilize lipase. J Mol Catal B Enzym 122:170–178 Kim JH, Shim BS, Kim HS, Lee YJ, Min SK, Jang D, Abas Z, Kim J (2015b) Review of nanocellulose for sustainable future materials. Int J Precis Eng Manuf Technol 2:197–213 Klemm D, Heublein B, Fink H-P, Bohn A (2005) Cellulose: fascinating biopolymer and sustainable raw material. Angew Chem Int Ed 44(22):3358–3393 Klemm D, Kramer F, Moritz S, Lindström T, Ankerfors M, Gray D, Dorris A (2011) Nanocelluloses: a new family of nature-based materials. Angew Chem Int Ed 50(24):5438–5466 Kobayashi Y, Saito T, Isogai A (2014) Aerogels with 3D ordered nanofiber skeletons of liquid-­ crystalline nanocellulose derivatives as tough and transparent insulators. Angew Chem Int Ed 53:10394–10397 Köhnke T, Lin A, Elder T, Theliander H, Ragauskas AJ (2012) Nanoreinforced xylan–cellulose composite foams by freeze-casting. Green Chem 14:1864–1869 Kojima Y, Minamino J, Isa A, Suzuki S, Ito H, Makise R, Okamoto M (2013) Binding effect of cellulose nanofibers in wood flour board. J Wood Sci 59:396–401 Kose R, Mitani I, Kasai W, Kondo T (2011) Nanocellulose as a single nanofiberprepared from pellicle secreted by Gluconacetobacter xylinus using aqueouscounter collision. Biomacromolecules 12(3):716–720 Koubaa A, Koran Z (1995) Measure of the internal bond strength of paper/board. TAPPI J 78(3):103–111 Kristak L, Antov P, Bekhta P, Lubis MAR, Iswanto AH, Reh R, Sedliacik J, Savov V, Taghiyari H, Papadopoulos AN, Pizzi A, Hejna A (2022) Recent progress in ultra-low formaldehyde emit-

286

A. Tozluoglu et al.

ting adhesive systems and formaldehyde scavengers in wood-based panels: a review. Wood Mater Sci Eng:1. https://doi.org/10.1080/17480272.2022.2056080 Kumar V, Bollström R, Yang A, Chen Q, Chen G, Salminen P, Bousfield D, Toivakka M (2014) Comparison of nano- and microfibrillated cellulose films. Cellulose 21:3443–3456 Kumar V, Elfving A, Koivula H, Bousfeld D, Toivakka M (2016) Roll-to-roll processed cellulose nanofber coatings. Ind Eng Chem Res 55(12):3603–3613 Kumar R, Sharma RK, Singh AP (2019) Grafting of cellulose with N-isopropylacrylamide and glycidyl methacrylate for efficient removal of Ni(II), Cu(II) and Pd(II) ions from aqueous solution. Sep Purif Technol 219:249–259 Labet M, Thielemans W (2012) Citric acid as a benign alternative to metal catalysts for the production of cellulose-grafted-polycaprolactone copolymers. Polym Chem 3(3):679–684 Labet M, Thielemans W, Dufresne A (2007) Polymer grafting onto starch nanocrystals. Biomacromolecules 8(9):2916–2927 Lakovaara M, Sirvi JA, Ismail MY, Liimatainen H, Sliz R (2021) Hydrophobic modification of nanocellulose and all-cellulose composite films using deep eutectic solvent as a reaction medium. Cellulose 28:5433–5447 Latifah J, Nurrul-Atika M, Sharmiza A, Rushdan I (2020) Extraction of nanofibrillated cellulose from kelempayan (Neolamarckia Cadamba) and its use as strength additive in papermaking. J Trop For Sci 32(2):170–178 Lavoine N, Bras J, Desloges I (2014a) Mechanical and barrier properties of cardboard and 3D packaging coated with microfibrillated cellulose. J Appl Polym Sci 131(8):40106 Lavoine N, Desloges I, Khelifi B, Bras J (2014b) Impact of different coating processes of microfibrillated cellulose on the mechanical and barrier properties of paper. J Mater Sci 49:2879–2893 Le Gars M, Delvart A, Roger P, Belgacem MN, Bras J (2020) Amidation of TEMPO-oxidized cellulose nanocrystals using aromatic aminated molecules. Colloid Polym Sci 298:603–617 Lee KY, Bismarck A (2014) Chapter 2 – Green chemical modifications of Nanocellulose for use in composites. In: Oksman K, Mathew AP, Bismarck A, Rojas O, Sain M (eds) Handbook of green materials: processing, characterization and properties. World Scientific Publishing Co Pte Ltd, Singapore, pp 7–18 Lee J, Deng Y (2011) The morphology and mechanical properties of layer structured cellulose microfibril foams from ice-templating methods. Soft Matter 7:6034–6040 Leung ACW, Hrapovic S, Lam E, Liu Y, Male KB, Mahmoud KA, Luong JHT (2011) Characteristics and properties of carboxylated cellulose nanocrystals prepared from a novel one-step procedure. Small 7(3):302–305 Li S, Xiao M, Zheng A, Xiao H (2011) Cellulose microfibrils grafted with pba via surface-initiated atom transfer radical polymerization for biocomposite reinforcement. Biomacromolecules 12(9):3305–3312 Li MC, Mei C, Xu X, Lee S, Wu Q (2016a) Cationic surface modification of cellulose nanocrystals: toward tailoring dispersion and interface in carboxymethyl cellulose films. Carbohydr Polym 107:200–210 Li Q, Chen W, Li Y, Guo X, Song S, Wang Q, Liu Y, Li J, Yu H, Zeng J (2016b) Comparative study of the structure, mechanical and thermomechanical properties of cellulose nanopapers with different thickness. Cellulose 23:1375–1382 Li B, Zhang Y, Wu C, Guo B, Luo Z (2018) Fabrication of mechanically tough and selfrecoverable nanocomposite hydrogels from polyacrylamide grafted cellulose nanocrysta and poly(acrylic acid). Carbohydr Polym 198:1–8 Liimatainen H, Visanko M, Sirviö JA, Hormi OEO, Niinimaki J (2012) Enhancement of the nanofibrillation of wood cellulose through sequential periodate–chlorite oxidation. Biomacromolecules 13(5):1592–1597 Liimatainen H, Ezekiel N, Sliz R, Ohenoja K, Sirviö JA, Berglund L, Hormi O, Niinimäki J (2013a) High-strength nanocellulose-talc hybrid barrier films. ACS Appl Mater Interfaces 5(24):13412–13418

Nanocellulose in Paper and Board Coating

287

Liimatainen H, Visanko M, Sirviö J, Hormi O, Niinimaki J (2013b) Sulfonated cellulose nanofibrils obtained from wood pulp through regioselective oxidative bisulfite pre-treatment. Cellulose 20(2):741–749 Liimatainen H, Suopajärvi T, Sirviö J, Hormi O, Niinimäki J (2014) Fabrication of cationic cellulosic nanofibrils through aqueous quaternization pretreatment and their use in colloid aggregation. Carbohydr Polym 103:187–192 Lin N, Dufresne A (2014) Surface chemistry, morphological analysis and properties of cellulose nanocrystals with gradiented sulfation degrees. Nanoscale 6:5384–5393 Lin N, Chen G, Huang J, Dufresne A, Chang PR (2009) Effects of polymer-grafted natural nanocrystals on the structure and mechanical properties of poly(lactic acid): a case of cellulose Whisker-graft-polycaprolactone. J Appl Polym Sci 113(5):3417–3425 Lin N, Huang J, Chang PR, Feng J, Yu J (2011) Surface acetylation of cellulose nanocrystal and its reinforcing function in poly(lactic acid). Carbohydr Polym 83(4):1834–1842 Lin N, Bruzzese C, Dufresne A (2012) TEMPO-oxidized nanocellulose participatingas crosslinking aid for alginate-based sponges. ACS Appl Mater Interfaces 4(9):4948–4959 Lin N, Chen Y, Hu F, Huang J (2015) Mechanical reinforcement of cellulose nanocrystals on biodegradable microcellular foams with melt compounding process. Cellulose 22:2629–2639 Liu A, Walther A, Ikkala O, Belova L, Berglund LA (2011) Clay nanopaper with tough cellulose nanofiber matrix for fire retardancy and gas barrier functions. Biomacromolecules 12(3):633–641 Liu D, Ma Z, Wang Z, Tian H, Gu M (2014) Biodegradable poly(vinyl alcohol) foams supported by cellulose nanofibrils: processing, structure, and properties. Langmuir 30:9544–9550 Liu P, Borrell PF, Bozic M, Kokol V, Oksman K, Mathew AP (2015) Nanocelluloses and their phosphorylated derivatives for selective adsorption of Ag+, Cu2+ and Fe3+ from industrial effluents. J Hazard Mater 294:177–185 Liu S, Jin M, Chen Y, Gao H, Shi X, Cheng W, Ren L, Wang Y (2017) High internal phase emulsions stabilised by supramolecular cellulose nanocrystals and their application as cell-adhesive macroporous hydrogel monoliths. J Mater Chem B 5(14):2671–2678 Lizundia E, Meaurio E, Vilas JL (2016) Chapter 3 – Grafting of cellulose nanocrystals. In: Puglia D, Fortunati E, Kenny JM (eds) Multifunctional polymeric nanocomposites based on cellulosic reinforcements. Elsevier Inc, Amsterdam, Holland, pp 61–113 Ljungberg N, Bonini C, Bortolussi F, Boisson C, Heux L, Cavaille JY (2005) New nanocomposite materials reinforced with cellulose whiskers in atactic polypropylene: effect of surface and dispersion characteristics. Biomacromolecules 6(5):2732–2739 Lönnberg H, Fogelström L, Berglund L, Malmström E, Hult A (2008) Surface grafting of microfibrillated cellulose with poly(𝜀-caprolactone)-synthesis and characterization. Eur Polym J 44(9):2991–2997 Lönnberg H, Larsson K, Lindström T, Hult A, Malmström E (2011) Synthesis of polycaprolactone-­ grafted microfibrillated cellulose for use in novel bionanocomposites – influence of the graft length on the mechanical properties. ACS Appl Mater Interfaces 3(5):1426–1433 Lourenço AF, Gamelas JAF, Nunes T, Amaral JL, Mutjè P, Ferreira PJT (2017) Influence of TEMPO-oxidised cellulose nanofibrils on the properties of filler-containing papers. Cellulose 24:349–362 Lourenço AF, Godinho D, Gamelas JAF, Sarmento P, Ferreira PJT (2019) Carboxymethylated cellulose nanofibrils in papermaking: influence on filler retention and paper properties. Cellulose 26:3489–3502 Lu Q, Lin W, Tang L, Wang S, Chen X, Huang B (2014a) A mechanochemical approach to manufacturing bamboo cellulose nanocrystals. J Mater Sci 50:611–619 Lu T, Li Q, Chen W, Yu H (2014b) Composite aerogels based on dialdehyde nanocellulose and collagen for potential applications as wound dressing and tissue engineering scaffold. Compos Sci Technol 94:132–138

288

A. Tozluoglu et al.

Lumiainen J (2000) Chapter 4: Refining of chemical pulp. In: Paulapuro H (ed) Papermaking science and technology, papermaking part 1: stock preparation and wet end. Fapey Oy, Helsinki, Finland, pp 86–122 Lynd LR, Weimer PJ, van Zyl WH, Pretorius IS (2002) Microbial cellulose utilization: fundamentals and biotechnology. Microbiol Mol Biol Rev 66(3):506–577 Macosko CW (1994) Rheology: principles, measurements, and applications, vol 41. VCH Publishers Inc, p 10 Mansouri S, Khiari R, Bettaieb F, El-Gendy AA, Mhenni F (2015) Synthesis and characterization of carboxymethyl cellulose from Tunisian vine stem Study of water absorption and retention capacities. J Polym Environ 23:190–198 Marchessault RH, Morehead FF, Walter NM (1959) Liquid crystal systems from fibrillar polysaccharides. Nature 184:632–633 Martoïa F, Cochereau T, Dumont PJJ, Orgéas L, Terrien M, Belgacem MN (2016) Cellulose nanofibril foams: links between ice-templating conditions, microstructures and mechanical properties. Mater Des 104:376–391 Marwanto M, Maulana MI, Febrianto F, Wistara NJ, Si N, Masruchin N, Zaini LH, Lee SH, Kim NH (2021) Effect of oxidation time on the properties of cellulose nanocrystals prepared from balsa and kapok fibers using ammonium persulfate. Polymers (Basel) 13(11):1894 Mascheroni E, Rampazzo R, Ortenzi MA, Piva G, Bonetti S, Piergiovanni L (2016) Comparison of cellulose nanocrystals obtained by sulfuric acid hydrolysis and ammonium persulfate, to be used as coating on flexible food-packaging materials. Cellulose 23(1):779–793 Mashkour M, Afra E, Resalati H, Mashkour M (2015) Moderate surface acetylation of nanofibrillated cellulose for the improvement of paper strength and barrier properties. RSC Adv 5(74):60179–60187 Masrol SR, Ibrahim MHI, Adnan S, Tajudin MSAA, Raub RA, Razak SNAA, Md Zain SNF (2016) Characteristics of linerboard and corrugated medium paper made from durian rinds chemi-mechanical pulp. MATEC Web Conf 51:1–10 Matyjaszewski K (2012) Atom transfer radical polymerization (ATRP): current status and future perspectives. Macromolecules 45(10):4015–4039 Mavelil-Sam R, Deepa B, Koshy RR, Mary SK, Pothan LA, Thomas S (2017) Rheological properties of nanocomposites based on cellulose nanofibrils and cellulose nanocrystals. In: Kargarzadeh H, Ahmad I, Thomas S, Dufresne A (eds) Handbook of nanocellulose and cellulose nanocomposites, 1st edn. Wiley-VCH Verlag GmbH & Co. KGaA Menezes AJD, Siqueira G, Curvelo AAS, Dufresne A (2009) Extrusion and characterization of functionalized cellulose whiskers reinforced polyethylene nanocomposites. Polymer 50(19):4552–4563 Meng T, Gao X, Zhang J, Yuan J, Zhang Y, He J (2009) Graft copolymers prepared by atom transfer radical polymerization (ATRP) from cellulose. Polymer 50(2):447–454 Messa LL, Faez R, Hsieh Y (2021) Phosphorylated cellulose nanofibrils from sugarcane bagasse with pH tunable gelation. Carbohydr Polym Technol Appl 2:100085 Meyabadi TF, Dadashian F, Sadeghi GMM, Asl HEZ (2014) Spherical cellulose nanoparticles preparation from waste cotton using a green method. Powder Technol 261:232–240 Michal BT, Brenn WA, Nguyen BN, McCorkle LS, Meador MAB, Rowan SJ (2016) Thermoresponsive shape-memory aerogels from thiol–ene networks. Chem Mater 28(7):2341–2347 Mishra SP, Manent AS, Chabot B, Daneault C (2012) The use of sodium chloritein post-oxidation of TEMPO-oxidized pulp: effect on pulp characteristics and nanocellulose yield. J Wood Chem Technol 32:137–148 Missoum K, Bras J, Belgacem MN (2012a) Organization of aliphatic chains grafted on nanofibrillated cellulose and influence on final properties. Cellulose 19:1957–1973 Missoum K, Bras J, Belgacem MN (2012b) Water redispersible dried nanofibrillated cellulose by adding sodium chloride. Biomacromolecules 13:4118–4125

Nanocellulose in Paper and Board Coating

289

Missoum K, Belgacem MN, Bras J (2013) Nanofibrillated cellulose surface modification: a review. Materials (Basel) 6:1745–1766 Moad G (2017) RAFT polymerization to form stimuli-responsive polymers. Polim Chem 8:177–219 Moon RJ, Martini A, Nairn J, Simonsen J, Youngblood J (2011) Cellulose nanomaterials review: structure, properties and nanocomposites. Chem Soc Rev 40(7):3941–3994 Montanari S, Roumani M, Laurent Heux A, Vignon MR (2011) Topochemistry of carboxylated cellulose nanocrystals resulting from tempomediated oxidation. Macromolecules 38(5):1665–1671 Morandi G, Thielemans W (2012) Synthesis of cellulose nanocrystals bearing photocleavable grafts by ATRP. Polym Chem 3:1402–1407 Morits M, McKee JR, Majoinen J, Malho JM, Houbenov N, Seitsonen J, Laine J, Gröschel AH, Ikkala O (2017) Polymer brushes on cellulose nanofibers: modification, SI-ATRP, and unexpected degradation processes. Chem Eng 5(9):7642–7650 Mormann W (2003) Silylation of cellulose with hexamethyldisilazane in ammonia—activation, catalysis, mechanism properties. Cellulose 10(3):271–281 Mu X, Gray DG (2014) Formation of chiral nematic films from cellulose nanocrystal suspensions is a two-stage process. Langmuir 30(31):9256–9260 Mukherjee SM, Woods HJ (1953) X-ray and electron microscope studies of the degradation of cellulose by sulphuric acid. Biochim Biophys Acta 10:499–511 Naderi A, Lindström T, Sundström J (2015) Repeated homogenization, a route for decreasing the energy consumption in the manufacturing process of carboxymethylated nanofibrillated cellulose. Cellulose 22:1147–1157 Naderi A, Sundström J, Lindström T, Erlandsson J (2016) Enhancing the properties of carboxymethylated nanofibrillated cellulose by inclusion of water in the pretreatment process. Nord Pulp Pap Res J 31(3):372–378 Naderi A, Koschella A, Heinze T et al (2017) Sulfoethylated nanofibrillated cellulose: production and properties. Carbohydr Polym 169:515–523 Nair SS, Zhu J, Deng Y, Ragauskas AJ (2014) High performance green barriers based on nanocellulose. Sustain Chem Process 2(23):1–7 Navarro JRG, Bergström L (2014) Labelling of N-hydroxysuccinimide-modified Rhodamine B on cellulose nanofibrils by the amidation reaction. RSC Adv 4:60757–60761 Nechyporchuk O, Belgacem MN (2016) Production of cellulose nanofibrils: a review of recent advances. Ind Crop Prod 93:2–25 Nelson K, Retsina T, Iakovlev M, van Heiningen A, Deng Y, Shatkin JA, Mulyadi A (2016) Chapter 9 – American process: production of low cost nanocellulose for renewable, advanced materials applications. In: Madsen LD, Svedberg EB (eds) Materials research for manufacturing: an industrial perspective of turning materials into new products. Springer, pp 267–302 Nemoto J, Saito T, Isogai A (2015) Simple freeze-drying procedure for producing nanocellulose aerogel-containing, high-performance air filters. ACS Appl Mater Interfaces 7(35):19809–19815 Nguyen BN, Cudjoe E, Douglas A, Scheiman D, McCorkle L, Meador MAB, Rowan SJ (2016) Polyimide cellulose nanocrystal composite aerogels. Macromolecules 49(5):1692–1703 Nickerson RF, Habrle JA (1947) Cellulose intercrystalline structure. Ind Eng Chem 39(11):1507–1512 Ninikas K, Mitani A, Koutsianitis D, Ntalos G, Taghiyari HR, Papadopoulos AN (2021) Thermal and mechanical properties of green insulation composites made from cannabis and bark residues. J Compos Sci 5:132 Nogi M, Iwamoto S, Nakagaito AN, Yano H (2009) Optically transparent nanofiber paper. Adv Mater 21(16):1595–1598 Norell M, Johansson K, Persson M (1999) Retention and drainage. In: Papermaking Science and Technology, Book 4: Papermaking Chemistry (Ed. Neimo L) Fapet Oy, Helsinki, Finland 43-81 Okita Y, Saito T, Isogai A (2010) Entire surface oxidation of various cellulose microfibrils by TEMPO-mediated oxidation. Biomacromolecules 11(6):1696–1700

290

A. Tozluoglu et al.

Oksman K, Mathew AP, Bismarck A, Rojas O, Sain M (2014) Handbook of green materials. World Scientific Publishing Co Pte Ltd, Singapore, 233–252 Olaru N, Olaru L, Stoleriu A, Timpu D (1998) Carboxymethylcellulose synthesis in organic media containing ethanol and/or acetone. J Appl Polym Sci 67:481–486 Olszewska A, Eronen P, Johansson LS, Malho JM, Ankerfors M, Lindstrom T, Ruokolainen J, Laine J, Österberg M (2011) The behaviour of cationic Nanofibrillar Cellulose in aqueous media. Cellulose 18(5):1213–1226 Osong SH, Norgren S, Engstrand P (2016) Processing of wood-based microfibrillar celluloseand nanofibrillated cellulose and applications relating to papermaking: a review. Cellulose 23:93–123 Österberg M, Vartiainen J, Lucenius J, Hippi U, Seppälä J, Serimaa R, Laine J (2013) A fast method to produce strong NFC films as a platform for barrier and functional materials. ACS Appl Mater Interfaces 5(11):4640–4647 Oun AA, Rhim JW (2017) Characterization of carboxymethyl cellulose-based nanocomposite films reinforced with oxidized nanocellulose isolated using ammonium persulfate method. Carbohydr Polym 174(15):484–492 Pääkkö M, Ankerfors M, Kosonen H, Nykänen A, Ahola S, Österberg M, Ruokolainen J, Laine J, Larsson PT, Ikkala O, Lindström T (2007) Enzymatic hydrolysis combined with mechanical shearing and high-pressure homogenization for nanoscale cellulose fibrils and strong gels. Biomacromolecules 8(6):1934–1941 Paës G, Chabbert B (2011) Characterization of arabinoxylan/cellulose nanocrystals gels to investigate fluorescent probes mobility in bioinspired models of plant secondary cell wall. Biomacromolecules 13:206–214 Pakherenco V, Pervaiz M, Pande H, Sain M (2017) Chemical and physical techniques for surface modification of nanocellulose reinforcements. In: Netravali AN, Mittal KL (eds) Interface/ interphase in polymer nanocomposites. Scrivener Publishing LLC, Beverly, pp 283–310 Palomero CR, Soriano ML, Valcárce M (2015) β-Cyclodextrin decorated nanocellulose: a smart approach towards the selective fluorimetric determination of danofloxacin in milk samples. Analyst 140(10):34313438 Pan ZZ, Nishihara H, Iwamura S, Sekiguchi T, Sato A, Isogai A, Kang F, Kyotani T, Yang QH (2016) Cellulose nanofiber as a distinct structure-directing agent for xylem-like microhoneycomb monoliths by unidirectional freeze-drying. ACS Nano 10(12):10689–10697 Pego MFF, Bianchi ML, Yasumura PK (2020) Nanocellulose reinforcement in paper produced from fber blending. Wood Sci Technol 54:1587–1603 Pei A, Malho JM, Ruokolainen J, Zhou Q, Berglund LA (2011) Strong nanocomposite reinforcement effects in polyurethane elastomer with low volume fraction of cellulose nanocrystals. Macromolecules 44(11):4422–4427 Peng Y, Gardner DJ, Han Y (2012) Drying cellulose nanofibrils: in search of a suitable method. Cellulose 19:91–102 Perez DD, Montanari S, Vignon MR (2003) TEMPO-mediated oxidation of cellulose III. Biomacromolecules 4(5):1417–1425 Petroudy SRD, Sheikhi P, Ghobadifar P (2017) Sugarcane bagasse paper reinforced by Cellulose Nanofiber (CNF) and Bleached Softwood Kraft (BSWK). Pulp J Polym Environ 25:203–213 Peyre J, Pääkkönen T, Reza M, Kontturi E (2015) Simultaneous preparation of cellulose nanocrystals and micron-sized porous colloidal particles of cellulose by TEMPO-mediated oxidation. Green Chem 17:808–811 Poyraz B, Tozluoglu A, Candan Z, Demir A (2017a) Matrix impact on the mechanical, thermal and electrical properties of microfluidized nanofibrillated cellulose composites. J Polym Eng 37(9):921–931 Poyraz B, Tozluoglu A, Candan Z, Demir A, Yavuz M (2017b) Influence of PVA and silica on chemical, thermo-mechanical and electrical properties of Celluclast-treated nanofibrillated cellulose composites. Int J Biol Macromol 104:384–392. https://doi.org/10.1016/j.ijbiomac.2017.06.018

Nanocellulose in Paper and Board Coating

291

Poyraz B, Tozluoglu A, Candan Z, Demir A, Yavuz M, BuyuksariU UHI, Fidan H, Saka RC (2018) TEMPO-treated CNF composites: pulp and matrix effect. Fibers Polymers 19(1):195–204. https://doi.org/10.1007/s12221-­018-­7673-­y Pracella M, Haque MMU, Puglia D (2014) Morphology and properties tuning of PLA/cellulose nanocrystals bio-nanocomposites by means of reactive functionalization and blending with PVAc. Polymer 55(16):3720–3728 Prakobna K, Berthold F, Medina L, Berglund LA (2016) Mechanical performance and architecture of biocomposite honeycombs and foams from core–shell holocellulose nanofibers. Compos A: Appl Sci Manuf 88:116–122 Puspasari T (2018) Versatile high-performance regenerated cellulose membranes prepared using trimethylsilyl cellulose as a precursor. Doctoral Thesis, University of King Abdullah, Saudi Arabia Qiang Y, Pan X (2010) A facile approach for fabricating fluorescent cellulose. J Appl Polym Sci 117:3639–3644 Rånby BG (1951) Fibrous macromolecular systems. Cellulose and muscle. The colloidal properties of cellulose micelles. Discuss Faraday Soc 11:158–164 Rantanen J, Maloney TC (2013) Press dewatering and nip rewetting of paper containing nano- and microfibril cellulose. Nord Pulp Pap Res J 28:582–587 Rasi M (2013) Permeability properties of paper materials. Doctoral Thesis, University of Jyväskylä, Finland Raza M, Abu-Jdayil B (2022) Cellulose nanocrystals from lignocellulosic feedstock: a review of production technology and surface chemistry modification. Cellulose 29:685–722 Rees A, Powell LC, Chinga-Carrasco G, Gethin DT, Syverud K, Hill KE, Thomas DW (2015) 3D bioprinting of carboxymethylated-periodate oxidized nanocellulose constructs for wound dressing applications. BioMed Res Int 2015:925757 Reid MS, Villalobos M, Cranston ED (2017) Benchmarking cellulose nanocrystals: from the laboratory to industrial production. Langmuir 33:1583–1598 Reshmy R, Philip E, Paul SA, Madhavan A, Raveendran S, Parameswaran B, Pandey A, Sirohi R (2020) Nanocellulose-based products for sustainable applications-recent trends and possibilities. Rev Environ Sci Biotechnol 19:779–806 Revol JF, Bradford H, Giasson J, Marchessault RH, Gray DG (1992) Helicoidal self-ordering of cellulose microfibrils in aqueous suspension. Int J Biol Macromol 14(3):170–172 Revol JF, Godbout L, Dong XM, Gray DG, Chanzy H, Maret G (1994) Chiral nematic suspensions of cellulose crystallites; phase separation and magnetic field orientation. Liq Cryst 16(1):127–134 Rezayati Charani P, Dehghani-Firouzabadi M, Afra E, Blademo A, Naderi A, Lindström T (2013) Production of microfbrillated cellulose from unbleached kraft pulp of Kenaf and Scotch Pine and its efect on the properties of hardwood kraft: microfbrillated cellulose paper. Cellulose 20:2559–2567 Ridgway CJ, Gane PAC (2012) Constructing NFC-pigment composite surface treatment for enhanced paper stiffness and surface properties. Cellulose 19:547–560 Risteen B, Delepierre G, Srinivasarao M, Weder C, Russo P, Reichmanis E, Zoppe J (2018) Thermally switchable liquid crystals based on cellulose nanocrystals with patchy polymer grafts. Small 14(46):1802060 Robles E, Csóka L, Labidi J (2018) Effect of reaction conditions on the surface modification of cellulose nanofibrils with aminopropyl triethoxysilane. Coatings 8(4):139 Rodionova G, Lenes M, Eriksen Ø, Gregersen Ø (2011) Surface chemical modification of microfibrillated cellulose: improvement of barrier properties for packaging applications. Cellulose 18:127–134 Roeder RD, Garcia-Valdez O, Whitney RA, Champagne P, Cunningham MF (2016) Graft modification of cellulose nanocrystals via nitroxide-mediated polymerisation. Polym Chem 7:6383–6390

292

A. Tozluoglu et al.

Roy D, Guthrie JT, Perrier S (2007) Nanocellulose, a versatile green platform: from biosources to materials and their applications. Soft Matter 4:145–155 Roy D, Knapp JS, Guthrie JT, Perrier S (2008) Antibacterial cellulose fiber via RAFT surface graft polymerization. Biomacromolecules 9:91–99 Roy D, Semsarilar M, Guthrie JT, Perrier S (2009) Cellulose modification by polymer grafting: a review. Chem Soc Rev 38:2046–2064 Rueda L, d’Arlas BF, Zhou Q, Berglund LA, Corcuera MA, Mondragon I, Eceiza A (2011) Isocyanate-rich cellulose nanocrystals and their selective insertion in elastomeric polyurethane. Compos Sci Technol 71(16):1953–1960 Ryu JH, Han NK, Lee JS, Jeong YG (2019) Microstructure, thermal and mechanical properties of composite films based on carboxymethylated nanocellulose and polyacrylamide. Carbohydr Polym 211:84–90 Saito T, Nishiyama Y, Putaux JL, Vignon M, Isogai A (2006) Homogeneous suspensions of individualized microfibrils from TEMPO-catalyzed oxidation of native cellulose. Biomacromolecules 7(6):1687–1691 Saito T, Kimura S, Nishiyama Y, Isogai A (2007) Cellulose nanofibers prepared by TEMPO-­ mediated oxidation of native cellulose. Biomacromolecules 8(8):2485–2491 Saito T, Hirota M, Tamura N, Kimura S, Fukuzumi H, Heux L, Isogai A (2009) Individualization of nano-sized plant cellulose fibrils by direct surface carboxylation using TEMPO catalyst under neutral conditions. Biomacromolecules 10(7):1992–1996 Saito T, Uematsu T, Kimura S, Enomae T, Isogai A (2011) Self-aligned integration of native cellulose nanofibrils towards producing diverse bulk materials. Soft Matter 7(19):8804–8809 Sakai K, Kobayashi Y, Saito T, Isogai A (2016) Partitioned airs at microscale and nanoscale: thermal diffusivity in ultrahigh porosity solids of nanocellulose. Sci Rep 6:20434–20441 Sanchez-Salvador JL, Balea AM, Monte C, Negro C, Miller M, Olson J, Blanco A (2020) Comparison of mechanical and chemical nanocellulose as additives to reinforce recycled cardboard. Sci Rep 10(1):3778 Sarkhosh Rahmani F, Talaeipoor M (2011) Study on production of fluting paper from wheat straw soda – AQ pulp and OCC pulp blends. Iranian J Wood Pap Sci Res 26:387–397 Segal L, Creely JJ, Martin AE, Conrad CM (1959) An empirical method for estimating the degree of crystallinity of native cellulose using the X-ray diffractometer. Text Res J 29(10):786–794 Sehaqui H, Allais M, Zhou Q, Berglund L (2011a) Wood cellulose biocomposites with fibrous structures at micro- and nanoscale. Compos Sci Technol 71:382–387 Sehaqui H, Zhou Q, Berglund LA (2011b) High-porosity aerogels of high specific surface area prepared from nanofibrillated cellulose (NFC). Compos Sci Technol 71(13):1593–1599 Shah N, Ul-Islam M, Khattak WA, Park JK (2013) Overview of bacterial cellulose composites: a multipurpose advanced material. Carbohydr Polym 98:1585–1598 Shang Q, Chen J, Hu Y, Yang X, Zhou Y (2021) Facile fabrication of superhydrophobic cross-­ linked nanocellulose aerogels for oil–water separation. Polymers 13(4):625 Sharma M, Aguado R, Murtinho D, Valente AJM, Mendes De Sousa A, Ferreira PHT (2020) A review on cationic starch and nanocellulose as paper coating components. Int J Biol Macromol 162:578–598 Sheikhi P, Asadpour G, Zabihzadeh SM, Amoee N (2013) An optimum mixture of virgin bagasse pulp and recycled pulp (OCC) for manufacturing fluting paper. BioRes 8(4):5871–5883 Shimizu M, Saito T, Nishiyama Y, Iwamoto S, Yano H, Isogai A, Endo T (2016) Fast and robust nanocellulose width estimation using turbidimetry. Macromol Rapid Commun 37(19):1581–1586 Shinoda R, Saito T, Okita Y, Isogai A (2012) Relationship between length and degree of polymerization of TEMPO-oxidized cellulose nanofibrils. Biomacromolecules 13(3):842–849 Siqueira G, Bras J, Dufresne A (2009) Cellulose whiskers versus microfibrils: influence of the nature of the nanoparticle and its surface functionalization on the thermal and mechanical properties of nanocomposites. Biomacromolecules 10:425–432 Siqueira G, Bras J, Dufresne A (2010a) New process of chemical grafting of cellulose nanoparticles with a long chain isocyanate. Langmuir 26:402–411

Nanocellulose in Paper and Board Coating

293

Siqueira G, Tapin-Lingua S, Bras J, da Silva PD, Dufresne A (2010b) Morphological investigation of nanoparticles obtained from combined mechanical shearing, and enzymatic and acid hydrolysis of sisal fibers. Cellulose 17:1147–1158 Siró I, Plackett D (2010) Microfibrillated cellulose and new nanocomposite materials: a review. Cellulose 17:459–494 Siró I, Plackett D, Hedenqvist M, Ankerfors M, Lindström T (2011) Highly transparent films from carboxymethylated microfibrillated cellulose: the effect of multiple homogenization steps on key properties. J Appl Polym Sci 119(5):2652–2660 Sirviö JA, Visanko M (2017) Anionic wood nanofibers produced from unbleached mechanical pulp by highly efficient chemical modification. J Mater Chem A 5(41):21828–21835 Sirviö JA, Ukkola J, Liimatainen H (2019) Direct sulfation of cellulose fibers using a reactive deep eutectic solvent to produce highly charged cellulose nanofibers. Cellulose 26:2303–2316 Smith DK, Bampton RF, Alexander WJ (1963) Use of new solvents for evaluating chemical cellulose for the viscose process. Ind Eng Chem Process Des Dev 2(1):57–62 Sobkowicz MJ, Braun B, Dorgan JR (2009) Decorating in green: surface esterification of carbon and cellulosic nanoparticles. Green Chem 11(5):680–682 Soliveri G, Meroni D, Cappelletti G, Annunziata R, Aina V, Cerrato G, Ardizzone S (2014) Engineered organic/inorganic hybrids for superhydrophobic coatings by wet and vapour procedures. J Mater Sci 49:2734–2744 Song Y, Sun Y, Zhang X, Zhou J, Zhang L (2008) Homogeneous quaternization of cellulose in NaOH/urea aqueous solutions as gene carriers. Biomacromolecules 9(8):2259–2264 Spence KL, Venditti RA, Rojas OJ, Habibi Y, Pawlak JJ (2011a) A comparative study of energy consumption and physical properties of microfibrillated cellulose produced by different processing methods. Cellulose 18:1097–1111 Spence KL, Venditti RA, Rojas OJ, Pawlak JJ, Hubbe MA (2011b) Water vapor barrier properties of coated and filled microfibrillated cellulose composite films. Bioresources 6(4):4370–4388 Spinella S, Giada LR, Liu B, John D, Youssef H, Jane-Marie R, Philippe D, Richard AG (2015) Modification of cellulose nanocrystals with lactic acid for direct melt blending with pla. AIP Conf Proc 1664:070019 Spinella S, Maiorana A, Qian Q, Dawson NJ, Hepworth V, McCallum SA, Ganesh M, Singer KD, Gross RA (2016) Concurrent cellulose hydrolysis and esterification to prepare a surface-­ modified cellulose nanocrystal decorated with carboxylic acid moieties. ACS Sustain Chem Eng 4(3):1538–1550 Stelte W, Sanadi AR (2009) Preparation and characterization of cellulose nanofibers from two commercial hardwood and softwood pulps. Ind Eng Chem Res 48(24):11211–11219 Stenstad P, Andresen M, Tanem BS, Stenius P (2008) Chemical surface modifications of microfibrillated cellulose. Cellulose 15:35–45 Su J, Zhang L, Batchelor W, Garnier G (2014) Paper engineered with cellulosic additives: effect of length scale. Cellulose 21:2901–2911 Subramanian R, Fordsmand H, Paulapuro H (2007) Precipitated calcium carbonate (PCC)—cellulose composite fillers: effect of PCC particle structure on the production and properties of uncoated fine paper. Bioresources 2(1):571–576 Sucaldito MR, Camacho DH (2017) Characteristics of unique HBr-hydrolyzed cellulose nanocrystals from freshwater green algae (Cladophora rupestris) and its reinforcement in starch-based film. Carbohydr Polym 169:315–323 Suflet DM, Chitanu GC, Popa VI (2006) Phosphorylation of polysaccharides: new results on synthesis and characterisation of phosphorylated cellulose. React Funct Polym 66:1240–1249 Suopajärvi T, Liimatainen H, Karjalainen M, Upola H, Niinimäki J (2015) Lead adsorption with sulfonated wheat pulp nanocelluloses. J Water Process Eng 5:136–142 Svagan AJ, Jensen P, Dvinskikh SV, Furó I, Berglund LA (2010) Towards tailored hierarchical structures in cellulose nanocomposite biofoams prepared by freezing/freeze-drying. J Mater Chem 20:6646–6654 Syverud K, Stenius P (2009) Strength and barrier properties of MFC films. Cellulose 16:75–85

294

A. Tozluoglu et al.

Taipale T, Österberg M, Nykänen A, Ruokolainen J, Laine J (2010) Effect of microfibrillated cellulose and fines on the drainage of kraft pulp suspension and paper strength. Cellulose 17:1005–1020 Tang J, Lee MFX, Zhang W, Zhao B, Berry RM, Tam KC (2014) Dual responsive pickering emulsion stabilized by poly[2-(dimethylamino) ethyl methacrylate] grafted cellulose nanocrystals. Biomacromolecules 15:3052–3060 Tang J, Berry RM, Tam KC (2016) Stimuli-responsive cellulose nanocrystals for surfactant-free oil harvesting. Biomacromolecules 17:1748–1756 Taniguchi T, Okamura K (1998) New films produced from microfibrillated natural fibres. Polym Int 47(3):291–294 Tarrés Q, Delgado-Aguilar M, Pelach MA, Gonzalez I, Boufi S, Mutje P (2016) Remarkable increase of paper strength by combining enzymatic cellulose nanofibers in bulk and TEMPO-­ oxidized nanofibers as coating. Cellulose 23(6):3939–3950 Tarrés Q, Aguado R, Àngels Pèlach M, Mutjé P, Delgado-Aguilar M (2022) Electrospray deposition of cellulose nanofibers on paper: overcoming the limitations of conventional coating. Nano 12:79 Tejado A, Alam MN, Antal M, Yang H, van de Ven TGM (2012) Energy requirements for the disintegration of cellulose fibers into cellulose nanofibers. Cellulose 19:831–842 Thakur V, Sharma E, Guleria A, Sangar S, Singh K (2020) Modification and management of lignocellulosic waste as an ecofriendly biosorbent for the application of heavy metal ions sorption. Mater Today Proc 32:608–619 Thakur V, Guleria A, Kumar S, Sharmad S, Singj K (2021) Recent advances in nanocellulose processing, functionalization and applications: a review. Mater Adv 2(6):1872–1895 Thomas B, Raj MC, Athira KB, Rubiyah MH, Joy J, Moores A, Drisko GL, Sanchez C (2018) Nanocellulose, a versatile green platform: from biosources to materials and their applications. Chem Rev 118(24):11575–11625 Thomas P, Duolikun T, Rumjit NP, Moosavi S, Lai CW, Bin Johan MR, Fen LB (2020) Comprehensive review on nanocellulose: recent developments, challenges and future prospects. J Mech Behav Biomed Mater 110:103884 Tingaut P, Hauert R, Zimmermann T (2011) Highly efficient and straightforward functionalization of cellulose films with thiol-ene click chemistry. J Mater Chem 21(40):16066–16076 Tozluoglu A, Poyraz B, Candan Z, Yavuz M, Arslan R (2017) Biofilms from micro/nanocellulose of NaBH4-modified kraft pulp. Bull Mater Sci 40(4):699–710. https://doi.org/10.1007/ s12034-­017-­1416-­y Tozluoglu A, Poyraz B, Candan Z (2018a) Examining the efficiency of mechanic/enzymatic pretreatments in micro/nanofibrillated cellulose production. Maderas-Ciencia Tecnol 20(1):67–84. https://doi.org/10.4067/S0718-­221X2018005001601 Tozluoglu A, Poyraz B, Mcdonald AG, Candan Z (2018b) Developing nanocellulose-based biofilms from kraft and NaBH4-modified kraft pulp. Cellul Chem Technol 52(3–4):223–237 Turbak AF, Snyder FW, Sandberg KR (1983) Microfibrillated cellulose, a new cellulose product: properties, uses, and commercial potential. J Appl Polym Sci Appl Polym Symp 37:815–827 Tutuş A, Gültekin S, Çiçekler M (2016) Effects of using starch at size press on physical and optical properties of some packing papers. 1st International Conference on ngineering Technology and Applied Sciences, Afyon-Turkey, pp 111–115 Tyagi P, Hubbe MA, Lucia LA, Pal L (2018) High performance nanocellulose-based composite coatings for oil and grease resistance. Cellulose 25:3377–3391 Tyagi P, Lucia LA, Hubbe MA, Pal L (2019) Nanocellulose-based multilayer barrier coatings for gas, oil, and grease resistance. Carbohydr Polym 206:281–288 Tzanov T, Stamenova M, Cavaco-Paulo A (2002) Phosphorylation of cotton cellulose with Baker’s yeast hexokinase. Macromol Rapid Commun 23(16):962–964 Uetani K, Yano H (2011) Nanofibrillation of wood pulp using a high-speed blender. Biomacromolecules 12(2):348–353

Nanocellulose in Paper and Board Coating

295

Uetani K, Yano H (2012) Zeta potential time dependence reveals the swelling dynamics of wood cellulose nanofibrils. Langmuir 28:818–827 Ul-Islam M, Ullah MW, Khan S, Kamal T, Ul-Islam S, Shah N, Park JK (2016) Recent advancement in cellulose based nanocomposite for addressing environmental challenges. Recent Pat Nanotechnol 10:169–180 Unbehend JE, Britt KW (1982) Retention, drainage, and sheet consolidation. Ind Eng Chem Prod Res Dev 21:150–153 URL 1. Fundamentals of an ATRP Reaction – Matyjaszewski Polymer Group – Carnegie Mellon University. https://www.cmu.edu/maty/chem/fundamentals-­atrp/ URL 2. Paper Properties. http://www.pulppapermill.com/category/paper-­properties URL 3. Properties of Paper. https://paperonweb.com/paperpro.htm URL 4. Smithers, Crush Tests. https://www.smithers.com/industries/packaging/ manufacturers-­­a nd-­u sers/packaging-­m aterials-­t esting/paper-­t esting-­p hysical-­p roperties/ crush-­tests Vardanyan V, Poaty B, Chauve G, Landry V, Galstian T, Riedl B (2014) Mechanical properties of UV-waterborne varnishes reinforced by cellulose nanocrystals. J Coat Technol Res 11(6):841–852 Vardanyan V, Galstian T, Riedl B (2015) Effect of addition of cellulose nanocrystals to wood coatings on color changes and surface roughness due to accelerated weathering. J Coat Technol Res 12(2):247–258 Vineeth SK, Gadhave RV, Gadekar PT (2019) Nanocellulose applications in wood adhesives— review. Open J Polym Chem 9:63–75 Wågberg L, Winter L, Ödberg L, Lindström T (1987) On the charge stoichiometry upon adsorption of a cationic polyelectrolyte on cellulosicmaterials. Colloids Surf 27:163–173 Wågberg L, Decher G, Norgren M, Lindström T, Ankerfors M, Axnas K (2008) The build-up of polyelectrolyte multilayers of microfibrillated cellulose and cationic polyelectrolytes. Langmuir 24(3):784–795 Wan J, Zhang J, Yu J, Zhang J (2017) Cellulose aerogel membranes with a tunable nanoporous network as a matrix of gel polymer electrolytes for safer lithium-ion batteries. ACS Appl Mater Interfaces 9(29):24591–24599 Wang S, Cheng Q (2009) A novel process to isolate fibrils from cellulose fibers byhigh-intensity ultrasonication, part 1: process optimization. J Appl Polym Sci 113(2):1270–1275 Wang JS, Matyjaszewski K (1995) Controlled/"living" radical polymerization. Halogen atom transfer radical polymerization promoted by a Cu (I)/Cu (II) redox process. Macromolecules 28:7901–7910 Wang B, Sain M (2007) The effect of chemically coated nanofiber reinforcement on biopolymer based nanocomposites. Bioresources 2(3):371–388 Wang B, Sain M, Oksman K (2007a) Study of structural morphology of hemp fiberfrom the micro to the nanoscale. Appl Compos Mater 14:89–103 Wang N, Ding E, Cheng R (2007b) Thermal degradation behaviors of spherical cellulose nanocrystals with sulfate groups. Polymer 48(12):3486–3493 Wang N, Ding E, Cheng R (2008) Preparation and liquid crystalline properties of spherical cellulose nanocrystals. Langmuir 24(1):5–8 Wang QQ, Zhu JY, Gleisner R, Kuster TA, Baxa U, McNeil SE (2012) Morphological development of cellulose fibrils of a bleached eucalyptus pulp by mechanical fibrillation. Cellulose 19:1631–1643 Wang Y, Wang X, Xie Y, Zhang K (2018) Functional nanomaterials through esterification of cellulose: a review of chemistry and application. Cellulose 25:3703–3731 Werner A, Schmitt V, Sèbe G, Héroguez V (2019) Convenient synthesis of hybrid polymer materials by AGET-ATRP polymerization of pickering emulsions stabilized by cellulose nanocrystals grafted with reactive moieties. Biomacromolecules 20:490–501

296

A. Tozluoglu et al.

Wicklein B, Kocjan A, Salazar-Alvarez G, Carosio F, Camino G, Antonietti M, Bergstrom L (2015) Thermally insulating and fireretardant lightweight anisotropic foams based on nanocellulose and graphene oxide. Nat Nanotechnol 10(3):277–283 Wu W, Li J, Zhu W, Jing Y, Dai H (2016) Thermo-responsive cellulose paper via ARGET ATRP. Fibers Polym 17(4):495–501 Wu Y, Wang L, Qing Y, Yan N, Tian C, Huang Y (2017) A green route to prepare fluorescent and absorbent nano-hybrid hydrogel for water detection. Sci Rep 7:1–11 Wu Z, Xu J, Gong J, Li J, Mo L (2018) Preparation, characterization and acetylation of cellulose nanocrystal allomorphs. Cellulose 25:4905–4918 Xiao M, Li S, Chanklin W, Zheng A, Xiao H (2011) Surface-initiated atom transfer radical polymerization of butyl acrylate on cellulose microfibrils. Carbohydr Polym 83(2):512–519 Xie H, Du H, Yang X, Si C (2018) Recent strategies in preparation of cellulose nanocrystals and cellulose nanofibrils derived from raw cellulose materials. Int J Polym Sci 5:1–25 Xu Q, Yi J, Zhang X, Zhang H (2008) A novel amphotropic polymer based on cellulose nanocrystals grafted with azo polymers. Eur Polym J 44(9):2830–2837 Xu Y, Kuang Y, Salminen P, Chen G (2016) The influence of nano-fibrillated cellulose as a coating component in paper coating. Bioresources 11(2):4342–4352 Xu J, Wua Z, Wua Q, Kuanga Y (2020) Acetylated cellulose nanocrystals with high-crystallinity obtained by one-step reaction from the traditional acetylation of cellulose. Carbohydr Polym 229:115553 Yamamoto H, Horii F, Odani H (1989) Structural changes of native cellulose crystals induced by annealing in aqueous alkaline and acidic solutions at high temperatures. Macromolecules 22:4130–4132 Yan M, Li S, Zhang M, Li C, Dong F, Li W (2013) Characterization of surface acetylated nanocrystalline cellulose by single-step method. Bioresources 8(4):6330–6341 Yan C, Wang J, Kang W, Cui M, Wang X, Foo CY, Chee KJ, Lee PS (2014) Highly stretchable piezoresistive graphene–nanocellulose nanopaper for strain sensors. Adv Mater 26:2022–2027 Yan J, Pan X, Schmitt M, Wang Z, Bockstaller MR, Matyjaszewski K (2016) Enhancing initiation efficiency in metal-free surface-initiated atom transfer radical polymerization (SI-ATRP). ACS Macro Lett 5:661–665 Yang X, Cranston ED (2014) Chemically cross-linked cellulose nanocrystal aerogels with shape recovery and superabsorbent properties. Chem Mater 26(20):6016–6025 Yang H, Nur Alam M, van de Ven TGM (2013a) Highly charged nanocrystalline cellulose and dicarboxylated cellulose from periodate and chlorite oxidized cellulose fibers. Cellulose 20:1865–1875 Yang J, Han CR, Duan JF, Ma MG, Zhang XM, Xu F, Sun RC (2013b) Synthesis and characterization of mechanically flexible and tough cellulose nanocrystals-polyacrylamide nanocomposite hydrogels. Cellulose 20:227–237 Yang S, Xie Q, Liu X, Wu M, Wangab S, Xueping S (2018) Acetylation improves thermal stability and transmittance in FOLED substrates based on nanocellulose films. RSC Adv 8(7):3619–3625 Yi J, Xu Q, Zhang X, Zhang H (2008) Chiral-nematic self-orderingof rodlike cellulose nanocrystals grafted with poly(styrene) in both thermotropic and lyotropic states. Polymer 49(20):4406–4412 Yi J, Xu Q, Zhang X, Zhang H (2009) Temperature-induced chiral nematic phase changes of suspensions of poly(N,N-dimethylaminoethyl methacrylate)-grafted cellulose nanocrystals. Cellulose 16(6):989–997 Yi T, Zhao H, Mo Q, Pan D, Liu Y, Huang L, Xu H, Hu B, Song H (2020) From cellulose to cellulose nanofibrils—a comprehensive review of the preparation and modification of cellulose nanofibrils. Materials 13(22):1–32 Yildirim M, Candan Z (2021) Performance properties of particleboard panels modified with nanocellulose/boric acid. Bioresources 16:1 Yildirim M, Candan Z, Gonultas O (2021) Chemical performance analysis of nanocellulose/boron compounds reinforced hybrid UF resin. Green Mater:1–8

Nanocellulose in Paper and Board Coating

297

Yildirim M, Candan Z, Aksoy B, Dundar T (2022) Physico-mechanical properties and formaldehyde emission of plywood panels by lignosulfonate-reinforced urea-formaldehyde adhesive. Green Mater:1–10 Yin Y, Tian X, Jiang X, Wang H, Gao W (2016) Modification of cellulose nanocrystal via SI-ATRP of styrene and the mechanism of its reinforcement of polymethylmethacrylate. Carbohydr Polym 142:206–212 Yoo S, Hsieh JS (2010) Enzyme-assisted preparation of fibrillated cellulose fibers and its effect on physical and mechanical properties of paper sheet composites. Ind Eng Chem Res 49(5):2161–2168 You X, Hu Q, Hu X, Chen H, Yang W, Zhang X (2019) An effective, economical and ultra-fast method for hydrophobic modification of NCC using poly(methylhydrogen)siloxane. Polymers 11(6):963 Yu H, Qin Z, Liang B, Liu N, Zhou Z, Chen L (2013) Facile extraction of thermally stable cellulose nanocrystals with a high yield of 93% through hydrochloric acid hydrolysis under hydrothermal conditions. J Mater Chem A 1(12):3938–3944 Yu J, Liu Y, Liu X, Wang C, Wang J, Chu F, Tang C (2014) Integration of renewable cellulose and rosin towards sustainable copolymers by “grafting from” ATRP. Green Chem 16:1854–1864 Yuan H, Nishiyama Y, Wada M, Kuga S (2006) Surface acylation of cellulose whiskers by drying aqueous emulsion. Biomacromolecules 7:696–700 Zaman M, Xiao H, Chibante F, Ni Y (2012) Synthesis and characterization of cationically modified nanocrystalline cellulose. Carbohydr Polym 89(1):163–170 Zhang C, Maric M (2011) Synthesis of stimuli-responsive, water-soluble poly[2-(dimethylamino) ethyl methacrylate/styrene] statistical copolymers by nitroxide mediated polymerization. Polymer 3(3):1398–1422 Zhang J, Elder TJ, Pu Y, Ragauskas AJ (2007) Facile synthesis of spherical cellulose nanoparticles. Carbohydr Polym 69(3):607–611 Zhang F, Sautter K, Larsen AM, Findley DA, Davis RC, Samha H, Linford MR (2010) Chemical vapour deposition of three aminosilanes on silicon dioxide: surface characterization, stability, efects of silane concentration, and cyanine dye adsorption. Langmuir 26:14648–14654 Zhang Z, Tingaut P, Rentsch D, Zimmermann T, Sèbe G (2015) Controlled silylation of nanofibrillated cellulose inwater: reinforcement of amodel polydimethylsiloxane network. ChemSusChem 8:2681–2690 Zhang X, Ma P, Zhang Y (2016) Structure and properties of surface-acetylated cellulose nanocrystal/poly(butylene adipate-co-terephthalate) composites. Polym Bull 73:20732085 Zhang Z, Tam KC, Sèbe G, Wang X (2018) Convenient characterization of polymers grafted on cellulose nanocrystals via SI-ATRP without chain cleavage. Carbohydr Polym 199:603–609 Zhang Z, Wang X, Tam KC, Sèbe G (2019) A comparative study on grafting polymers from cellulose nanocrystals via surface-initiated atom transfer radical polymerization (ATRP) and activator re-generated by electron transfer ATRP. Carbohydr Polym 205:322–329 Zhang Z, Sèbe G, Hou Y, Wang J, Huang J, Zhou G (2021) Grafting polymers from cellulose nanocrystals via surface-initiated atom transfer radical polymerization. J Appl Polym Sci 138:e51458 Zhao M, Li J, Mano E, Song Z, Tschaen DM, Grabowski EJJ, Reider PJ (1999) Oxidation of primary alcohols to carboxylic acids with sodium chlorite catalyzed by TEMPO and bleach. J Org Chem 64(7):2564–2566 Zhao D, Huang J, Zhong Y, Li K, Zhang L, Cai J (2016a) High-strength and high-toughness double-­cross-linked cellulose hydrogels: a new strategy using sequential chemical and physical cross-linking. Adv Funct Mater 26(34):6279–6287 Zhao J, Zhao Y, Wang Z, Peng Z (2016b) Effect of polymorphs of cellulose nanocrystal on the thermal properties of poly(lactic acid)/cellulose nanocrystal composites. Eur Phys J E 39:118–125 Zhou C, Wu Q, Zhang Q (2011) Dynamic rheology studies of in situ polymerization process of polyacrylamide-cellulose nanocrystal composite hydrogels. Colloid Polym Sci 289:247–255

298

A. Tozluoglu et al.

Zhou S, Wang M, Chen X, Xu F (2015) Facile template synthesis of microfibrillated cellulose/ polypyrrole/silver nanoparticles hybrid aerogels with electrical conductive and pressure responsive properties. ACS Sustain Chem Eng 3(12):3346–3354 Zhu G, Lin N (2019) Chapter 5 – Surface chemistry of nanocellulose. In: Huang J, Dufresne A, Lin N (eds) Nanocellulose from fundamentals to advanced materials. Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany Zhu H, Fang Z, Preston C, Li Y, Hu L (2014) Transparent paper: fabrications, properties, and device applications. Energy Environ Sci 7:269–287 Zhu H, Luo W, Ciesielski PN, Fang Z, Zhu JY, Henriksson G, Himmel ME, Hu L (2016) Wood-­ derived materials for green electronics, biological devices, and energy applications. Chem Rev 116(16):9305–9374 Zimmermann T, Pöhler E, Geiger T (2004) Cellulose fibrils for polymer reinforcement. Adv Eng Mater 6(9):754–761 Zimmermann MVG, da Silva MP, Zattera AJ, Campomanes Santana RMJ (2017) Effect of nanocellulose fibers and acetylated nanocellulose fibers on properties of poly(ethylene-co-vinyl acetate) foams. Appl Polym Sci 134(17):44760 Zoppe JO, Habibi Y, Rojas OJ, Venditti RA, Johansson LS, Efimenko K, Österberg M, Laine J (2010) Poly(N-isopropylacrylamide) brushes grafted from cellulose nanocrystals via surface-­initiated single-electron transfer living radical polymerization. Biomacromolecules 11:2683–2691 Zubik K, Singhsa P, Wang Y, Manuspiya H, Narain R (2017) Thermo-responsive poly(Nisopropylacrylamide)-cellulose nanocrystals hybrid hydrogels for wound dressing. Polymers (Basel) 9(4):119

Green Materials for Radiation Shielding: An Overview Ertuğrul Demir, Zeki Candan, Ning Yan, Araz Rajabi-Abhari, Özlem Vural, Matlab Mirzayev, Evgeni Popov, S. İpek Karaaslan, and Bülent Büyük

Contents 1  I ntroduction 2  G  reen Materials 2.1  Lignocellulosic Biomaterials 2.2  Lignin-Containing Nanocellulose 3  Radiation 3.1  Radiation Types 3.2  Interactions of Radiation with Matter 3.3  Important Parameters for Radiation Shielding 3.4  Conventional Radiation Shielding Materials 4  Green Materials for Radiation Shielding Applications 4.1  Green Materials for X-Rays, Gamma-Rays, and Neutrons Shielding Applications 4.2  Green Materials for Electromagnetic Interference Shielding Applications 5  Conclusion References

 300  301  301  304  306  307  308  309  311  313  313  318  323  324

E. Demir (*) Yeditepe University, Faculty of Arts and Sciences, Physics Department, Istanbul, Turkey Biomaterials and Nanotechnology Research Group & Nano Team, Istanbul, Turkey Department of Nuclear Engineering, North Carolina State University, Raleigh, USA e-mail: [email protected] Z. Candan Biomaterials and Nanotechnology Research Group & Nano Team, Istanbul, Turkey Department of Forest Industrial Engineering, Istanbul University Cerrahpasa, Istanbul, Turkey N. Yan · A. Rajabi-Abhari Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 H. R. Taghiyari et al. (eds.), Emerging Nanomaterials, https://doi.org/10.1007/978-3-031-17378-3_9

299

300

E. Demir et al.

1 Introduction X-rays, gamma-rays, and neutrons are members of the ionizing radiation family that can give rise to chemical, biological, and microstructural harmful effects. As nuclear applications become more widely utilized in various fields such as the food industry, aviation, energy, space exploration, and diagnosis and therapy in medicine, the necessity for shielding materials to ensure safety and reduce radiation exposure is expanding. Hence, it is an undeniable fact that there is a need for environmentally friendly, low-cost materials with good radiation shielding properties to be protected from the harmful effects of ionizing radiation used in many different fields. Due to their increased photon interaction probability, materials with a high atomic number (Z) have a superior X- and gamma-ray shielding efficiency than materials with a lower Z. Lead, stainless steel, copper, and other high-Z materials have traditionally been used as radiation shielding materials to reduce the unwanted effects of X-ray and gamma radiation. Traditional shielding materials, which are discussed in the previous paragraph on the other hand, are rigid solids, heavy, and frequently hazardous to the environment. When it comes to the neutrons, they are a kind of particle radiation that has no net electric charge and hence cannot be halted by electric forces and are commonly utilized at nuclear power facilities to produce nuclear energy. However, most radiation shielding materials are inflexible solids and that is why they do not provide comfy radiation protection services in the radiation shielding applications. Despite the fact that polymer matrices are less effective in radiation shielding than metals, they have some significant properties like low cost, flexibility, chemical stability, and process ability. Adding nanomaterials into the polymer matrix is one of the methods in order to improve the radiation shielding capability of the materials. However, it is to be noted that finding a suitable polymer matrix for equally dispersing nanoparticles with radiation shielding characteristics in the polymer is a challenge. Green-based materials have good properties to fabricate novel, flexible, eco-friendly, and green radiation shielding materials.

Ö. Vural · S. İ. Karaaslan Yeditepe University, Faculty of Arts and Sciences, Physics Department, Istanbul, Turkey M. Mirzayev Azerbaijan State Oil and Industry University, Scientific-Research Institute Geotechnological Problems of Oil, Gas and Chemistry, Baku, Azerbaijan Joint Institute For Nuclear Research, Dubna, Moscow, Russia E. Popov Joint Institute For Nuclear Research, Dubna, Moscow, Russia Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia, Bulgaria B. Büyük Faculty of Engineering and Natural Sciences, Bandırma Onyedi Eylül University, Bandırma, Balıkesir, Turkey

Green Materials for Radiation Shielding: An Overview

301

This chapter presents the applications and radiation protection properties of green-based materials against different types of radiation. In this context, green-­ based materials produced for shielding against X-ray, gamma, neutron, and electromagnetic interference (EMI) radiations obtained from studies in the literature are evaluated and discussed in the following subsections.

2 Green Materials Before investigating the use of bio-based materials in radiation applications, the structure and types of these materials are intended to be discussed in this section. Petroleum-based polymers are extensively used in modern society due to their relative ease of synthesis, extreme durability, and inexpensiveness. However, the harmful environmental impact of plastic pollution around the globe is well-­ acknowledged. The public environmental awareness, plastic waste management legislation by governments, and depletion of fossil resources have caused reasonable restriction against the application of synthetic petroleum-based polymers. Therefore, efforts have been made to find alternative resources for environmentally friendly materials. In this regard, the application of nature-driven biodegradable materials has attracted significant research interest to develop a green society (Cywar et al. 2022). Bio-based materials are produced by renewable natural resources and exhibit excellent biocompatibility. While discarded in the environment, bio-based materials can be easily degraded by microorganisms. Bio-based materials are widespread and can be obtained from plant residues such as bark, straw, rice husks, bagasse, corn stover, and even marine products including shellfish and seaweed (De Corato et al. 2018; Antov et al., 2020, 2021; Aristri et al. 2021; Kristak et al. 2022). Hence, bio-­ based materials would be better alternatives to petroleum-based polymers by not imposing significant environmental impacts and contributing to the construction of a low-carbon society. Bio-based materials are generally abundant and can be obtained from different sources from land to sea. In contrast with petroleum-based polymers, bio-based materials are generally produced through simple and green processes with a less negative impact on the environment. Compared with complex and high-cost recycling processes of synthetic polymers, the recycling methods of the bio-based materials are simple, green, and less expensive. Opposite to the synthetic plastics which remain in nature for a very long period of time, nature-based materials are biodegradable in a short time after being exposed in the environment.

2.1 Lignocellulosic Biomaterials Lignocellulosic biomaterials can be described as a 3D biopolymer structure formed by bonding cellulose, lignin, and hemicellulose with small amounts of extractives and inorganic materials. Bio-based materials can be extracted from various sources of natural organisms from land to sea. In this section, some of the bio-based materials will be introduced.

302

E. Demir et al.

2.1.1 Cellulose Cellulose, the most abundant natural polymer can be extracted from plants, bacteria, algae, and animals (Dufresne 2013; Klemm et  al. 2005; Poyraz et  al. 2017a, b). Cellulose is a linear polymer constructed by repeating units of D-glucopyranosyl linked by β-1,4-glycosidic bonds. The glucose units are linked together to produce elementary fibrils, microfibrils, and finally, form cellulosic fibers (Fig. 1a). In the lignocellulosic cellulose, characteristics such as hydrophilicity, insolubility in most organic solvents, and chemical modifiability are closely governed by the degree of polymerization (DP) and supramolecular structure of cellulose (Klemm et al. 2005). The cellulose chain contains both crystalline and amorphous domains. The crystallinity of cellulose is dependent on the source and extraction process. In some sources such as bacterial cellulose or seeds of cotton, cellulose can be found in almost pure form. In the lignocellulosic sources, however, cellulose forms a composite with lignin, hemicellulose, and extractive compounds. Cellulose can be obtained through the elimination of non-cellulosic components by delignification and bleaching (Klemm et al. 2005). Application of mechanical or chemical treatments can isolate nanocellulose including cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs), as shown in Fig. 1b (Habibi et al. 2010; Poyraz et al. 2018; Tozluoglu et al. 2017, 2018a; Zhang et al. 2013). CNFs contain crystalline and amorphous regions in their supramolecular structure and can be obtained only by mechanical treatment through physical

Fig. 1  Wood-based materials (a) schematic illustration of cellulose microfibrils and chemical structure of cellulose. (Adapted from: Tian et al. 2019). (b) SEM micrographs of cellulose nanofibrils (left) and TEM image of cellulose nanocrystals (right). (Adapted from: Chauhan and Yan 2015; Tian et  al. 2019) (c) Lignin and its structure, sinapyl alcohol (blue), coniferyl alcohol (green), and coumaryl alcohol (red). (Adapted from: Ma et al. 2021a) (d) SEM image of lignin-­ containing cellulose nanofibrils. (Adapted from: C. wei Zhang et al. 2020b)

Green Materials for Radiation Shielding: An Overview

303

disintegration with or without pretreatments and can be produced through only physical disintegration of fibrils by mechanical treatment (Zhang et  al. 2013). On the other hand, strong acid hydrolysis is the primary method to obtain CNCs by the dissolution of the amorphous regions of cellulose fibers, which functionalizes the CNC surfaces by ester groups on the CNC surfaces (Habibi et al. 2010). Hence, compared with CNFs, CNCs carry more negative charges on the surface that provides better chemical stability in an aqueous environment. In comparison with synthetic polymers, cellulose and its derivatives show excellent biodegradation and biocompatibility. Very unique and outstanding characteristics, including very high mechanical strength, biocompatibility, high surface area, high aspect ratio, transparency, and being chemically modifiable, propose nanocellulose as a promising candidate for a variety of uses (Dufresne 2013). Nanocellulose materials in form of nanofibrils, nanowhiskers, nanocomposites, hydrogels, or aerogels have been used for a wide range of fields and applications such as papermaking additives, barrier packaging, adhesive, biocomposite materials, energy storage, energy harvesting, actuators, sensors, electromagnetic interference (EMI) shielding, X-ray shielding, and biomedical applications (Candan et al. 2016, 2022; Hubbe et al. 2017; Kim et al. 2015; Tozluoglu et al. 2018b; Li et al. 2021; Nair et al. 2019; Oh et al. 2017; Rajabi-Abhari et al. 2021; Wan et al. 2021; Yildirim and Candan 2021; Yildirim et al. 2021; Zhang et al. 2018). 2.1.2 Lignin Lignin, an amorphous and randomly branched polymer, is the second most abundant compound in wood structure after cellulose. Lignin is composed of three monomers, i.e., coniferyl alcohol, p-coumaryl alcohol, and sinapyl alcohol (Fig. 1c). The frequency of these monomers varies depending on the origin and separation methods of lignin (Ma et al. 2021a). Thereby, different types of bonds are formed during the polymerization process. This in turn results in the formation of woods with different physical and mechanical properties. Softwoods’ lignin mainly contains coniferyl alcohol, while sinapyl alcohol and coniferyl alcohol form the hardwood lignin. The lignin in grasses has all three monomers (Ma et al. 2021a). Lignin can be separated during various processes from different natural sources by depolymerization of lignin polymer into low molecular weight lignin fragments. Different parameters of the lignin separation method including temperature, pH, and solvents have a crucial influence on the structure of the final product (Chen et al. 2019; D’Souza et al. 2017; Yang et al. 2012). According to the separation process, commercial lignin can be classified into five main categories: kraft lignin, lignin sulfonate, organosolv lignin, alkaline lignin, and enzymatic lignin (Fig. 1c). Kraft pulping process accounts for the majority of global lignin production (Yu and Kim 2020). In this process, the ether bonds of lignin are broken by sodium hydroxide and sodium sulfide, and the lignin is dissolved into the black liquor. Then, under acidic conditions, the kraft lignin precipitated from the black liquor (Ma et  al. 2021a). Isolated lignin from the sulfite pulping process contains significant amounts of sulfur in the form of sulfonate groups, which is called lignin sulfonate and is widely available (Yu and Kim 2020). Alkaline lignin is formed by heating wood at about 160 °C in sodium hydroxide solution to allow the breakage of the ether bond and

304

E. Demir et al.

release of free aromatic compounds. Compared with kraft lignin, alkaline lignin has less impurity and lower molecular weight (Ma et al. 2021a). Lignin obtained from the degradation of wood by the catalytic action of enzymes is known as enzymatic lignin. The preparation of such lignin is relatively easy, but it usually contains some impurities, such as polysaccharides. Organosolv Lignin with high purity can be isolated from cellulose and hemicellulose using organic solvents. Compared to other methods, such as kraft pulping, Organosolv extraction of lignin is more environmentally friendly. The high cost and difficulty of solvent recovery, however, limit its application for commercial production. Lignin has been widely used for a variety of uses such as flocculants, adhesives, wood-based composite panels, concrete additives, bio-based foams and composites, pharmaceutical, biomedical, and energy applications (Ma et al. 2021a, b; Stojanovska et al. 2018, 2019; Tang et al. 2020; Yu and Kim 2020; Yildirim et al. 2022).

2.2 Lignin-Containing Nanocellulose Despite the excellent above-mentioned characteristics and performance of nanocellulose, elimination of lignin and nanocellulosic components dramatically reduces the yield of the production. Moreover, nanocellulose liberation from the hierarchical structure of cellulose fibers is an extremely energy-consuming process and usually needs chemical or enzymatic pretreatments (Im et al. 2018; Spence et al. 2011). In addition, the utilization of nanocellulose for various composite applications is restricted due to its hydrophilic nature, and poor thermal stability of pure cellulose. On contrary, preserving covalently bonded lignin with cellulose offers significant beneficial effects. The nanofibrillation process with the presence of lignin provides advantages such as high production yields, low costs, and reduced chemical waste (Fig. 1d). Non-polar hydrocarbons together with benzene groups on the lignin structure prevent hydrogen bonding between cellulose fibers and water molecules and consequently improve the hydrophobicity and water vapor barrier of cellulose (Huang et al. 2019). Furthermore, lignin provides additional benefits including thermal stability, thermoplasticity, antioxidant activity, and enhanced mechanical properties at high humidity (Huang et al. 2019; Nair and Yan 2015; Solala et al. 2020). Lignin-­ containing nanocellulose (LCNF) has been recently used for various advanced applications such as barrier packaging (Zhang et al. 2020b, 2022), bio-composites (Wang et al. 2020a), adhesive (Chen et al. 2020), gas sensing (Tanguy et al. 2022a), energy storage (Tanguy et al. 2021), and energy harvesting (Tanguy et al. 2022b). 2.2.1 Starch Starch is a high molecular abundant biopolymer and is formed naturally in various plants such as corn, potato, wheat, and rice through photosynthesis. Starch granules are composed of linear amylose (10–30%) and highly branched amylopectin (70–90%). Starch has high biodegradability, processability, and film formation properties. Starch films are brittle and blending with plasticizers can decrease the

Green Materials for Radiation Shielding: An Overview

305

brittleness and enhance the mechanical properties. Polylactic acid (PLA) is a derivative of starch that is fermented by microorganisms and chemically synthesized from starch, and exhibits excellent biodegradability, biocompatibility, transparency, heat resistance, and plasticity. Besides its utilization in the food industry, starch has been widely used in the papermaking, coating, and packaging industries (Abhari et al. 2018; Bergman and Bao 2004; Maurer 2009). Starch and its derivatives have been also used for other important fields such as adhesive, textiles, cosmetics, and paint (Hebeish et  al. 2005; Tratnik et  al. 2020; Wang et al. 2020b), or other advanced applications including water treatments, drug delivery, self-healing polymers, energy storage, X-ray, and EMI-shielding applications (Ogunsona et al. 2018; Qi et al. 2021; Zhang et al. 2020a). 2.2.2 Chitosan Chitosan is an abundant natural amino-rich biopolymer that is obtained by deacetylation of chitin. Chitin is driven from the shell of marine crustaceans, basically phones and crabs, and is widely available in nature. Chitosan has excellent biocompatibility, biodegradability, and mechanical strength and its properties change with the molecular weight and degree of acetylation. Chitosan has been used in various fields of applications such as papermaking, textile, water treatment, pharmaceutical, cosmetics, food, chemistry, biomedical engineering, energy storage, energy harvesting, and EMI shielding (Kim et al. 2020; Morin-Crini et al. 2019; Tan et al. 2022). 2.2.3 Natural Proteins Natural proteins can be classified into two major group’s animal and plant proteins. Silk fiber, collagen, wool, gelatin, egg white, and keratin are considered major animal proteins and exhibit excellent biocompatibility and biodegradability. Fruit of cereals, soy protein, and rice protein are easy to obtain, inexpensive, sustainable, and abundant plant proteins and are attracting great interest due to their biodegradability, easy processing, and excellent film formation. Natural polymers are widely applied in medicine, drug delivery, wearable electronics, implantable medical devices, energy harvesting, and EMI shielding (Babu et al. 2013; Hou et al. 2019; Lee et al. 2013; Li et al. 2020a; Tan et al. 2022). 2.2.4 Synthetic Biopolymers Recently, extensive efforts have been made to synthesize biopolymers with advanced functionalities. Synthetic biopolymers should demonstrate identical or superior properties over existing products to be substituted with the existing petroleum-­ based polymers. To produce these bio-based polymers, the natural biopolymers are deconstructed into the building blocks (monomers) including fatty acids, amino acids, monomeric sugars, and lignin monomers. Bio-derived monomers then can be directly polymerized into synthetic bio-based polymers.

306

E. Demir et al.

If the monomers are not directly polymerizable, they can be first transformed into precursors for synthesizing bio-based polymers such as polyurethanes, polycarbonates, polyamides, and epoxy resins and then polymerized to biopolymers (Babu et al. 2013; Cywar et al. 2022; Ma et al. 2021a; Wang et al. 2020a). These synthetic bio-based polymers exhibit outstanding properties such as high mechanical strength, tunability, high Tg, biodegradability, and less toxicity and have been used for various uses including coatings, biomedical materials, energy applications, and EMI shielding (Cywar et al. 2022). The use of materials such as cellulose, nanocellulose, lignin, starch, and chitosan, which are introduced under the title of green materials in this section, in the field of radiation is very limited. In this context, studies to be conducted with these materials will not only contribute to the literature but also create topics that are expected to be explored in nuclear studies in the future. In the following sections, first of all, the definition of radiation, its types, interaction with the material, and traditionally used radiation shielding materials will be introduced. Afterward, radiation armor materials developed on the basis of conventionally used radiation shielding materials or with green-based materials in the form of composites will be mentioned.

3 Radiation Until around 1900, electromagnetic waves were referred to as radiation. Electrons, X-rays, and natural radioactivity were found at the turn of the century and were grouped together under the word “radiation”. In contrast to electromagnetic radiation, which was viewed as a wave, the newly found radiation had particle properties. Today, the term “radiation” encompasses the whole electromagnetic spectrum as well as all known atomic and subatomic particles. Ionizing and non-ionizing radiation is one of the various ways in which different forms of radiation are classified. The capacity of radiation to ionize an atom or molecule in the medium it passes through is referred to as ionization. Nonionizing radiation is electromagnetic radiation having a wavelength of at least 10 nanometers (nm). Radio waves, microwaves, visible light (A = 770–390 nm), and UV light (A = 390–10 nm) are all part of the electromagnetic spectrum. The rest of the electromagnetic spectrum (X-rays, A = 0.01–10 nm) and γ-rays with wavelengths shorter than X-rays are considered ionizing radiation. It also contains electrons, positrons, protons, alphas, neutrons, heavy ions, and mesons, among other atomic and subatomic particles (Tsoulfanidis 1995). In this section, as a first, radiation types will be discussed in order to understand the characteristics of these radiations.

Green Materials for Radiation Shielding: An Overview

307

3.1 Radiation Types Radiation originates from atomic or nuclear processes that can be categorized as charged particle radiation-heavy charged particles, fast electrons and uncharged radiation-electromagnetic radiation and neutrons. Heavy particles include all the energetic ions with mass such as alpha particles, protons, and nuclear fission fragments. Alpha particles consist two protons and two neutrons. Heavy nuclei undergo spontaneous alpha decay ( 24 He ) as a result of their instability. The decay process is as follows: A Z



X

A4 Z 2

Y  24

X and Y are the parent and daughter nucleus, respectively (Knoll 2000). A radioisotope that decays through beta-minus emission is the most prevalent source of fast electrons in radiation measurements. A neutron-rich radioactive nucleus transforms from a neutron into a proton and ejects an antineutrino and beta particle (Podgorsak 2006). The procedure is depicted as follows in the diagram:

A Z

X

Y    

A Z 1

X and Y are the parent and daughter nucleus, respectively. υ is the antineutrino. Gamma-rays are high-energy photons with very short wavelengths and thus very high frequency. They have an energy higher 100 keV and their wavelength is less than 10 pm (Al-Tersawy et al. 2021). An excited nuclei emit gamma-rays when they move from higher to lower energy levels. A form of beta decay causes the population of the excited state in the descendant nucleus. When a gamma-ray photon emits with an energy about equal to the difference in energy between the starting and final nuclear states, this is known as de-excitation. General equation of gamma decay is given by:

A Z

X   ZA X  00

Neutrons are indirectly ionizing particles due to having no charge and they move through a material without any interaction (Sabry et al. 2022). When studying neutrons, it is easier to classify them according to their energies. They can be in thermal equilibrium with their environment at the low end of the scale. The Maxwell– Boltzmann formula is then used to disperse their energy. A thermal neutron has an energy of 0.025 eV at room temperature a, which is the most likely energy in the distribution at ambient temperature (20  °C). Thermal neutrons have an average energy of 0.038 eV at room temperature. It is not necessary for thermal–neutron distributions to conform to room temperature. Some facilities create “cold” neutrons with lower “temperatures,” whereas others produce neutrons with energy distributions typical of temperatures far over 20  °C.  Through elastic scattering in

308

E. Demir et al.

materials, thermal neutrons gain and lose only modest quantities of energy. They disperse until they are caught by atomic nuclei. Higher-energy neutrons, up to roughly 0.01  MeV or 0.1  MeV (the convention is not exact), are referred to as “slow,” “intermediate,” or “resonance.” Neutrons of the next higher-energy category, up to roughly 10 MeV or 20 MeV, are referred to be “fast.” Neutrons that are “relativistic” have even greater energy (Balasundar et al. 2021; Dunning et al. 1935). Heavy-ion beams are widely used in industrial and nuclear technology including radiation damage investigations in nuclear reactors and radiotherapy (Kurudirek 2016). These ions interact with the electrons in the target material, causing it to be excited and ionized. The material’s reaction to these processes is determined by its thermal and mechanical characteristics, and the formation of ion tracks as heavy ions enter a solid can change some of these features (Demir et al. 2022).

3.2 Interactions of Radiation with Matter Photon interactions are mediated by three mechanisms which are elastic or inelastic photon scattering, photoelectric effect, and pair production. Because no energy is permanently taken up by the irradiated substance, elastic scattering (or Rayleigh scattering) is an attenuation without an absorption process. Inelastic scattering (or Compton scattering) is another kind of photon scattering in which the photon transmits some of its energy to the electron and scatters with less energy and increased wavelength. With the energy lost by the incoming photon, the electron recoils, and the photon scatters with a new longer wavelength. In Compton scattering, the incident photon disappears and some of its energy is used to eject an electron from the atom and the rest is to emit characteristic radiation. When a photon with an energy equal to or more than the mass of two electrons (i.e., 2 × 511 keV = 1.02 MeV) interacts with a nucleus or an electron from the target, an electron-positron pair is produced which is called pair production. The electron is absorbed by a positive ion and becomes a neutral atom, while the positron interacts with another electron in the target, resulting in two annihilation photons of equal energy (511 keV) (Barabash et al. 2019). Radiation interaction mechanisms that are directly related to the absorption of the radiation in the material vary according to the radiation type; thus, effective radiation shielding differs for radiation type as well (Alzahrani et al. 2022). Alpha particles have a short range in tissue about 40–90  μ m and high linear energy transfer (LET) (Sgouros 2008). Most of the time, one to three particle tracks across the cell nucleus are enough to sterilize the cell, indicating that alpha density has a significant influence on living cells. Only when alpha particles are inhaled, digested, or absorbed via a wound are they harmful (Ismail and Sola 2022). Beta particles have two external hazards which are beta particles themselves and the production of Bremsstrahlung radiation when they interact with matter. The shielding of beta particles can be achieved by using a thicker material than their range. Since bremsstrahlung occurs with materials with high atomic numbers, thick

Green Materials for Radiation Shielding: An Overview

309

enough and low atomic number substances can be used to minimize the hazard (Turner 2007). Ionizing radiation such as X – and gamma-rays is extremely hazardous to the human body thus needing effective shielding (Turner 2007). The linear attenuation coefficient defines the penetration of gamma-ray in the matter. Because the photoelectric effect is the most dominant for high-Z materials, lead (Pb), tungsten (W), and iron (Fe) are used to shield X and gamma radiation (Mehrara et al. 2021). Lead has been the most used gamma radiation shield thanks to its high atomic number and high density (Jamal AbuAlRoos et al. 2020). Since neutron sources produce a vast range of energy, shielding against neutrons is a difficult undertaking. Due to the low neutron absorption cross-sectional values, fast neutrons become more problematic. As a result, a methodology for attenuating fast neutrons via elastic or inelastic scattering followed by thermal neutron absorption is required. Hydrogen-rich materials are well known for their ability to moderate thermal neutrons. The presence of scattering and secondary photon generation is an extra phenomenon that must be considered during the design of shielding materials (Balasundar et al. 2021).

3.3 Important Parameters for Radiation Shielding In order to properly evaluate the radiation shielding properties of materials, the following parameters should be known. In this context, density, effective atomic number, linear and mass attenuation coefficients, half-value layer (HVL), and tenth-value layer (TVL) thicknesses of the material are determinative parameters for radiation shielding properties. To be able to compute the radiation attenuation properties of mixtures and compounds, their atomic number is needed. In such circumstances, the effective atomic number (Zeff) is calculated based on the assumption that the compound or mixture contains just one type of particle. The atomic number provided by many elements present in the substance is equivalent to the effective atomic number (Prabhu et al. 2020). When electromagnetic radiation interacts with matter, the intensity of radiation is reduced. This attenuation is given by Beer–Lambert’s law:

I  I0e x

Where I and I0 are the initial and final intensity of the radiation, x is the thickness of the absorbing material and μ is the linear attenuation coefficient. A high linear attenuation coefficient means effective radiation shielding. The linear attenuation coefficient depends on the energy of the incident photon, the atomic number, and the density of the material. The mass attenuation coefficient determines the amount of energy absorbed in the material. It is a fundamental quantity used in medical and health physics to assess the energy deposition in a material by X-ray or gamma-ray photons, and it is crucial in determining the absorbed dose (Singh et al. 2018).

310



E. Demir et al.

 

 

Where μρ and μ are are the mass and linear attenuation coefficients, respectively. The density of the material is denoted ρ. The half-value layer is the thickness that reduces the radiation intensity by half. The fact that the HVL of the material is small denotes that it has excellent gamma-­ ray shielding qualities (Dong et al. 2017; Kavaz et al. 2022). HVL is inversely proportional to the mass attenuation coefficient of the material and can be given as: HVL 

ln 2 

The thickness of a given substance that attenuates X-ray or gamma radiation to the degree that the intensity of radiation is lowered to one-tenth of the value measured without the material is referred to as a tenth-value layer or “TVL” (Hosseini et al. 2022). TVL 

ln10 

While evaluating the radiation shielding properties of materials, some theoretical programs are also used. In this context, XCOM and Monte Carlo GATE simulation stand out as frequently encountered studies in the literature. Many scientific, technical, and medical applications require knowledge of photon scattering and absorption. In this context, there is an increase in materials whose photon cross sections need to be known. However, not all materials have photon cross sections in the tables. In the fields of the atomic nucleus and atomic electrons, the XCOM program calculates total cross sections, attenuation coefficients, and partial cross sections for the following processes: photoelectric absorption, incoherent scattering, coherent scattering, and pair production. The partial and total mass interaction coefficients, which are equal to the product of the relevant cross sections times the number of target molecules per unit mass of the material, are listed for compounds. The mean free paths between photoelectric absorption events and pair production events are the reciprocals of these interaction coefficients. The overall attenuation coefficient is equal to the sum of the interaction coefficients for the separate processes. Moreover, XCOM generates the cross sections and attenuation coefficients efficiently for any element, compound, or combination at energies ranging from 1 keV to 100 GeV. XCOM has two output options: (a) tables that are formatted similarly to those seen in the literature; (b) graphical representations of tabular data (Gerward et al. 2004). GATE (Geant4 Application for Emission Tomography) is an open-source Monte Carlo simulation program and a macro language which uses Geant4 in the background. Commands should be input as macro files that include an organized batch

Green Materials for Radiation Shielding: An Overview

311

of commands to create a simulation in GATE. The input file includes source, detector, and material geometry as well as physics processes. The root is a data analysis software created by CERN. Obtained Root output files from the simulation are used to determine monoenergetic gamma attenuation coefficients of the samples for certain energies. Gate uses standard energy physics modules to define the physics process. Rayleigh scattering, photoelectric effect, Compton scattering, pair production, and electron interactions such as Bremsstrahlung, electron ionization, and multiple scattering are among the simulation modules (Ozyurt et al. 2018).

3.4 Conventional Radiation Shielding Materials In this subsection, elements/materials that are frequently utilized in radiation shielding applications will be discussed. The purpose of this section is to provide information about the materials to be used as additives during the development of bio-based materials. Depending on the type of radiation to which the strategic site is exposed, the protection materials are diverse and cover different parts of the protection spectrum. Some of the protective materials are used due to their high density and high atomic number, lack of nuclear reactions, others due to their ability to capture irradiated particles and subsequently rapid nuclear decay. Here, it will be discussed to classify shielding materials according to their specific radiation protection properties. In general, radiation shielding properties are associated with the atomic number of a particular element. For this reason, combined protections often use materials—alloys or composites, of several different elements. In this part, we will make a preliminary division of the elements into three groups: light (the beginning of the Mendelian table), in the middle, and heavy elements. As an example of high-energy photons, X-rays and gamma-rays are used as standards to protect concrete blocks with lead additives. However, as it is well known, when it comes to some types of radiation, in the standard situation, it is mostly accompanied by at least one other type of radiation such as beta + together with gamma, and neutrons together with gamma-rays. Here, it will be mentioned that the improvement of radiation shielding properties of materials by using materials or composites that are similar to lead atomic numbers but will provide good protection against X- and gamma-rays. Tungsten is an element that is widely considered a potential candidate for material in the areas subject to high temperature and radiation dynamics. However, many questions arise related to the possibility of optimizing its thermo-mechanical, radiation, and activation properties (El-Atwani et al. 2019; Ni et al. 2021; Nogami et al. 2021a; Oliver et al. 2020; Pintsuk et al. 2019). To overcome the disadvantages of tungsten (Katoh et al. 2019; M mohammadreza et al. 2020), alloying with suitable elements/materials can be made which will compensate for its thermo-mechanical disadvantages (Nogami et  al. 2021a; Wen et  al. 2017). Therefore, new alloys or ceramic composites have been tested for their resistance to radiation under various experimental conditions (Kurishita et al. 2008; Nogami et al. 2021b; Wen et al. 2017).

312

E. Demir et al.

If a light carbon atom is added to the heavy tungsten atom, materials are obtained that can kinetically absorb the wide variety of electronic and nuclear reactions required to capture gamma-rays on the one hand and radiation from ions on the other. In this way, another promising material is emerging on the scene—tungsten carbide (WC), which, in addition to its thermo-physical advantages, also possesses a combination of favorable nuclear properties (high thermal absorption cross section, high atomic packing, etc.) (Humphry-Baker and Smith 2019; Oliver et al. 2020). For this material, there is some empirical information about its behavior on irradiation, summarized by Humphry-Baker and Smith (Humphry-Baker and Smith 2019). However, there are little available experimental data for the same material, but with the addition of cobalt (Co) as the binder component (Humphry-Baker and Smith 2019; Oliver et al. 2020). Also known as “hard metals,” cemented tungsten carbides with cobalt as a binder at different volume fractions (WC-wt% Co) are widely used in cutting tools, rock drilling, and machining tools due to their high strength and hardness, resistance to breakage and resistance at high temperatures (Fries et al. 2022; He et al. 2018b; Humphry-Baker and Smith 2019; Oliver et al. 2020). These attractive mechanical properties for WC–Co cemented carbides are a consequence of their complex material structure (Kanerva et  al. 2016; Lee et  al. 2015; Su et al. 2016; Yan et al. 2019). In addition, the increased ductility due to the presence of Co is expected to result in less sputtering of the material from the volume, which should lead to reduced secondary ionization. We would like to make a smooth transition to another material of this type, where again a combination of heavy and light elements is used. In this context, tungsten-based borides are of interest because, in addition to the desired beneficial properties, boron’s high cross section against neutrons offers additional advantages. Along with this, it will also be useful to mention the materials that are entirely in the group of “light elements”. Materials such as boron carbide (B4C) have a number of applications, such as in nuclear technology, solar energy, electronics, engineering optimization, refractory, and shock protection, based on their excellent properties such as high melting point, thermal stability, exceptional abrasion, high hardness, low density, and high thermal neutron absorption cross section (Checker et al. 2015; Domnich et al. 2011; Gunjishima et al. 2001; Luo et al. 2011). Their ability to resist change in variable temperatures makes them in exceptional demand. Numerous reports of heat treatment and irradiation (gamma, electron, neutron, and fast ion irradiation) of boron composites have been found (Mirzayev et  al. 2018, 2019, 2020; Zubov et al. 2005). As a representative of the materials that are a combination of the groups of light and medium elements, we will consider titanium carbide (TiC). It is from the transition metal series having a rock-salt crystal structure that has drawn in extensive considerations as a material for extreme environments due to its very high melting temperature, high hardness, and good thermal and electrical conductivities (Huber et al. 2003; Tjong and Ma 2011). This material is also widely used for the production of cutting tools, heat-resistant hard alloys, and abrasive and anti-wear materials (Azadi et al. 2014; Hedaiatmofidi et al. 2014; Mhadhbi 2020). TiC has high mechanical resistance, minimal fission products, and small neutron capture cross sections

Green Materials for Radiation Shielding: An Overview

313

(Rasaki et  al. 2018) and is therefore considered to be a promising candidate for reactor material (IAEA 2010) as well as first wall material for thermonuclear reactors and for components in nuclear technology (Wirth et al. 2011). So far, a brief overview of potential candidates for different types of radiation protection has been made. However, these are not all possible combinations of materials and chemical elements. In order to obtain some in-depth analysis of radiation materials, it should be noted that most of the materials mentioned so far are a kind of layered structures. In this context, morphological, structural, mechanical, optical, and radiation shielding properties of the aforementioned materials can be seen below: W—atomic number: 74, space group: 229, crystal system: body center cubic, melting point: 3422  °C, density: 19.25  g/cm3, decomposes to stable, suitable for gamma protection, alpha protection, and beta protection. WC-Co—alloy, hard metals, cemented tungsten carbides with cobalt as a binder at different volume fractions, suitable for gamma protection alpha protection, beta protection, and ion radiation protection. WB (W2B, W5B2, WB2)—hard metals, layered structures, suitable for gamma protection alpha protection, beta protection, ion radiation protection, and neutron protection. TiC—hard metals, rock-salt crystal structure, layered structures, melting point: 3160 °C, decomposes to stable, suitable for alpha protection, beta protection, ion radiation protection. TiB (Ti2B, Ti5B2, TiB2)—hard metals, layered structures, suitable for alpha protection, beta protection, ion radiation protection, and neutron protection. B4C—hard metals, trigonal crystal system with space group 166, there is having many allotropic forms, suitable for neutron protection.

4 Green Materials for Radiation Shielding Applications 4.1 Green Materials for X-Rays, Gamma-Rays, and Neutrons Shielding Applications For decades, X-rays/gamma-rays have been regarded as the most prevalent type of radiation utilized in medical and industrial applications, especially in medical diagnosis and therapy (Hilbert et  al. 2007; Huber-Wagner et  al. 2009; Klingenbeck-­ Regn et al. 1999; Sampson et al. 2006; Sierink et al. 2016). X-rays from medical diagnostics are the leading radiation source of public exposure, according to several studies (Noor Azman and Ramzun 2021). Even though X-rays have numerous benefits in the medical profession and other uses, without effective X-ray shielding, a human might be at severe risk when exposed to them directly or indirectly. Lead has largely been used as a shielding material to protect human beings and the environment from the destructive effects of X-rays. Nevertheless, lead (Pb) is one of the most harmful contaminants to creatures in farmland, including plants, animals, and people (Hamid et  al. 2019; Kelepertzis 2014; Meyers et  al. 2009). Natural and human processes such as sewage treatment, mining, and industrial

314

E. Demir et al.

disposal release it into the environment (Zhu et al. 2013). Pb may accumulate in plants through root absorption, inhibiting their growth and development and finally killing them (Gao et al. 2022; Pidatala et al. 2018). Traditional shielding materials for X-ray radiation shielding, on the other hand, include lead sheet, cement, alloy, and lead rubber. While lead and its derivatives provide good radiation shielding properties, the high toxicity, heavy, and low flexibility of these materials have negative consequences (Li et al. 2020b). Hence, their usage as a radiation shielding material is becoming increasingly important owing to its harmful nature. As a result, scientists have been concentrating their efforts in recent years on inventing innovative X-ray shielding materials that are harmless, safe, and inexpensive (Al-Hadeethi and Sayyed 2020; Dong et al. 2018). Recently, polymers, graphene, and carbon nanotubes as green and sustainable materials have been trying to replace conventionally used metals in radiation shielding applications. For this purpose, green materials and long-term solutions are developed and studies are carried out to use them as sustainable alternatives. Therefore, the use of polymers as an X-ray shielding material is being investigated as a viable material to overcome conventional derivatives of lead’s weakness. Due to its outstanding qualities such as low toxicity and cost efficiency, several researchers have been attempting to develop polymer composites to take the place of the lead as the X- and gamma-ray shielding material. Lead-free, ecologically sustainable, and innovative X/gamma-ray shielding materials are now possible because to advances in nanotechnology. Epoxy resin is a low-cost, flexible, long-lasting, and plentiful substance. It is a very valuable choice in a broad application field. Therefore, epoxy-based composites have been developed in recent years as new types of protective materials, especially in X- and gamma-ray applications. In addition, for radiation shielding, an epoxy matrix composite with large quantities of high-Z fillers has emerged as a promising candidate. However, most of the current research is on X-ray or low-­ energy gamma-ray shielding composites. It can also be said that there are fewer studies on neutron shielding compared to X- and gamma-rays in the literature. In this context, radiation shielding properties of new polymer and epoxy composites for X-rays, gamma-rays, and neutrons shielding applications are the emphasis of this section. Lopresti et  al. reported that outstanding polymer-based composites for X-ray shielding (Lopresti et al. 2020). The purpose of studying and developing composite lightweight materials for X-ray shielding applications was to replace standard lead and steel screens. Simulations using Geant4 software were used to create new epoxy-based composites with barium sulfate and bismuth oxide additives. According to the study, these novel materials have similar shielding properties to the traditional materials. Moreover, they are lighter, more readily made, more practical, have a lesser environmental effect, and are less harmful to humans comparatively against to traditional shielding materials. They were concluded that 20% epoxy/60% bismuth oxide/20% barite, which provides the best X-ray shielding performance, largely surpassing steel, but at a cost of around 60% higher and with a weight reduction of around 60%.

Green Materials for Radiation Shielding: An Overview

315

Because of its large neutron cross section, boron is the most often utilized material in neutron shielding. In 2002, Gwaily et al. (Gwaily et al. 2002) reported that thermal neutron radiation shielding was investigated using composites of conductive natural rubber (40 HAF/NR) loaded with varying amounts of boron carbide (B4C). For the composite containing 20  phr of B4C, the maximum result for the linear absorption coefficient was 0.34 cm−1. High-density polyethylene (HDPE) composites incorporating modified boron nitride (mBN) fillers were produced with an organosilane. These composites’ characteristics and performances were compared to those of composites with pristine BN and boron carbide (B4C) fillers. According to this work, authors claimed that the HDPE/mBN composites outperformed the virgin BN and B4C composites in terms of radiation shielding, thermoconductive, and mechanical characteristics (Shin et al. 2014). According to the study of Li et  al., lightweight, flexible, wearable, and high shielding effectiveness natural leather (NL)-based composite protection materials can significantly advance present X-ray protection material research. In this context, it has been manufactured a co-doped Bi/Ce-NL composite (taking advantages of environmentally friendly and high X-ray radiation shielding ability of bismuth and cerium) with excellent X-ray attenuation in the energy range of 20–120 keV. The composed Bi/Ce-NL with 1.4 mm thickness and 1.51 mmol cm−3 MNPs loading revealed superior performance with roughly 100% attenuation at energy range