Polymer Based Bio-nanocomposites: Properties, Durability and Applications (Composites Science and Technology) 9811685770, 9789811685774

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Composites Science and Technology

Chandrasekar Muthukumar Senthil Muthu Kumar Thiagamani Senthilkumar Krishnasamy Rajini Nagarajan Suchart Siengchin   Editors

Polymer Based Bio-nanocomposites Properties, Durability and Applications

Composites Science and Technology Series Editor Mohammad Jawaid, Laboratory of Biocomposite Technology, Universiti Putra Malaysia, INTROP, Serdang, Malaysia

Composites Science and Technology (CST) book series publishes cutting edge research monographs (both edited and authored volumes) comprehensively covering topics shown below: • Composites from agricultural biomass/natural fibres include conventional composites-Plywood/MDF/Fiberboard • Fabrication of Composites/conventional composites from biomass and natural fibers • Wood, and Wood based materials • Chemistry and biology of Composites and Biocomposites • Modelling of damage of Composites and Biocomposites • Failure Analysis of Composites and Biocomposites • Structural Health Monitoring of Composites and Biocomposites • Durability of Composites and Biocomposites • Thermal properties of Composites and Biocomposites • Flammability of Composites and Biocomposites • Tribology of Composites and Biocomposites • Bionanocomposites and Nanocomposites • Applications of Composites, and Biocomposites To submit a proposal for a research monograph or have further inquries, please contact springer editor, Ramesh Premnath ([email protected]).

More information about this series at https://link.springer.com/bookseries/16333

Chandrasekar Muthukumar · Senthil Muthu Kumar Thiagamani · Senthilkumar Krishnasamy · Rajini Nagarajan · Suchart Siengchin Editors

Polymer Based Bio-nanocomposites Properties, Durability and Applications

Editors Chandrasekar Muthukumar School of Aeronautical Sciences Hindustan Institute of Technology and Science Chennai, India Senthilkumar Krishnasamy Department of Mechanical Engineering Francis Xavier Engineering College Tirunelveli, Tamil Nadu, India

Senthil Muthu Kumar Thiagamani Department of Mechanical Engineering Kalasalingam Academy of Research and Education Krishnankoil, India Rajini Nagarajan Department of Mechanical Engineering Kalasalingam Academy of Research and Education Krishnankoil, Tamil Nadu, India

Suchart Siengchin Department of Materials and Production Engineering The Sirindhorn International Thai–German Graduate School of Engineering (TGGS) King Mongkut’s University of Technology North Bangkok Bangkok, Thailand

ISSN 2662-1819 ISSN 2662-1827 (electronic) Composites Science and Technology ISBN 978-981-16-8577-4 ISBN 978-981-16-8578-1 (eBook) https://doi.org/10.1007/978-981-16-8578-1 © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2022 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 Singapore Pte Ltd. The registered company address is: 152 Beach Road, #21-01/04 Gateway East, Singapore 189721, Singapore

We dedicate this book to our beloved parents

Preface

Technological inventions in nanotechnology and nanofillers have revolutionized the industrial sector in a number of ways. Polymer composites reinforced with the various nanofillers have found widespread use in applications ranging from construction, aerospace, automotive sector, biomedical and electronics. The threat to the environment from the disposal of synthetic materials which has limited recycling capabilities has put an emphasis on the sustainable materials from the renewable sources such as plants, trees and their extracts. Thus, fabrication and characterization of the novel bionanocomposites has been the focus of scientific community in the recent times. This book could be of significant interest to the scientific community, academicians such as undergraduate and postgraduate students, research scholars and professionals looking to gain technical knowledge on the morphological behavior, dispersion characteristics of nanofillers within the polymers, parameters influencing the properties of the Bionanocomposites, mechanism governing the enhancement of properties at various concentrations of the nanofiller and their failure behavior under various static and dynamic loads. It also provides insight on the latest research trends in the field of bionanocomposites. The chapters in this book are organized in the following ways: Chapters “Morphological Characterization of Bio-nanocomposites” and “Ballistic Impact Properties of the Bionanocomposites” emphasize on thermal properties, flammability characteristics, antimicrobial properties, static and dynamic response of the bionanocomposites under mechanical loads. The next two chapters will discuss about the utilization of wood fiber and agro-wastes in composite application. Chapters “Water Absorption and Thickness Swelling Characteristic of the Bionanocomposites” and “Soil Burial and Biodegradability of Bionanocomposites” provide detailed information on the durability of bionanocomposites under various aging conditions. Chapters “Life Cycle Assessment, Recycling and Re-Use of the Bionanocomposites” and “Computational Modeling of the Bio– nanocomposites” cover up the lifecycle assessment of the bionanocomposites and

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studies on computational modeling. Chapters “Bionanocomposites in the Automotive and Aerospace Applications” and “Nanofiber-Reinforced Bionanocomposites in Agriculture Applications” discuss the applications of bionanocomposites in various industrial sectors. Chennai, India Krishnankoil, India Tirunelveli, India Krishnankoil, India Bangkok, Thailand

Chandrasekar Muthukumar Senthil Muthu Kumar Thiagamani Senthilkumar Krishnasamy Rajini Nagarajan Suchart Siengchin

Acknowledgements We appreciate the cooperation and support from the acquisition editor of the Springer, Singapore, staff members of the publisher and typesetter associated with this project.

Contents

Morphological Characterization of Bio-nanocomposites . . . . . . . . . . . . . . . Sivanjineyulu Veluri, Dipjyoti Bora, Upendra Nath Gupta, Emmanuel Rotimi Sadiku, A. Babul Reddy, and J. Jayaramudu

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Thermal Properties of the Poly(Lactic Acid) Bionanocomposites . . . . . . . R. Z. Khoo and W. S. Chow

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Thermal Stabilities of Bionanocomposites at Elevated Temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Samuel Eshorame Sanni, Emmanuel Rotimi Sadiku, and Emmanuel Emeka Okoro Flammability Properties of the Bionanocomposites Reinforced with Fire Retardant Filler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ajinkya Satdive, Saurabh Tayde, and Aniruddha Chatterjee Antimicrobial Properties of Bionanocomposites . . . . . . . . . . . . . . . . . . . . . . Aswathy Jayakumar, Sabarish Radoor, Jasila Karayil, Indu C. Nair, Suchart Siengchin, Jyotishkumar Parameswaranpillai, and E. K. Radhakrishnan

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Barrier Properties of Bionanocomposite Films . . . . . . . . . . . . . . . . . . . . . . . 103 Martin A. Hubbe, Emily V. Piner, Nathalie Lavoine, and Lucian A. Lucia Tensile, Flexural and Compressive Properties of the Bionanocomposites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 S. J. Amith Kumar Ballistic Impact Properties of the Bionanocomposites . . . . . . . . . . . . . . . . . 141 Alcides Lopes Leao, Ivana Cesarino, Otavio Dias, Ryszard Koslowski, and Mohammad Jawaid

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Contents

Water Absorption and Thickness Swelling Characteristic of the Bionanocomposites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 Siti Hasnah Kamarudin, Mohd Nurazzi Norizan, Fatirah Fadil, Syaiful Osman, and So’bah Ahmad Soil Burial and Biodegradability of Bionanocomposites . . . . . . . . . . . . . . . 181 Shiji Mathew and E. K. Radhakrishnan Life Cycle Assessment, Recycling and Re-Use of the Bionanocomposites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205 W. K. Kupolati, Emmanuel Rotimi Sadiku, A. A. Eze, I. D. Ibrahim, and O. Agboola Computational Modeling of the Bio-nanocomposites . . . . . . . . . . . . . . . . . . 217 Oladipo Folorunso, Yskandar Hamam, Emmanuel Rotimi Sadiku, and Suprakas Sinha Ray Bionanocomposites in the Automotive and Aerospace Applications . . . . . 237 Nabila Ali and Md Enamul Hoque Bio Nanocomposite Films in the Food Packaging Applications . . . . . . . . . 255 Sabarish Radoor, Jasila Karayil, Sruthi Damodaran, Aswathy Jayakumar, Jyotishkumar Parameswaranpillai, and Suchart Siengchin Bio-nanocomposites in Biomedical Application . . . . . . . . . . . . . . . . . . . . . . . 275 Theivasanthi Thirugnanasambandan Bionanocomposites in the Construction and Building Applications . . . . . 293 Ajinkya Satdive, Saurabh Tayde, Shyam Tonde, Chinmay Hazra, Debasree Kundu, and Aniruddha Chatterjee Nanofiber-Reinforced Bionanocomposites in Agriculture Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311 Juliana Botelho Moreira, Suelen Goettems Kuntzler, Bruna Pereira Vargas, Allana Arcos Comitre, Jorge Alberto Vieira Costa, and Michele Greque de Morais

Contributors

O. Agboola Department of Chemical Engineering, College of Engineering, Covenant University, Ota, Nigeria So’bah Ahmad School of Industrial Technology, Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM), Shah Alam, Selangor, Malaysia Nabila Ali Department of Materials and Metallurgical Engineering, Bangladesh University of Engineering and Technology (BUET), Dhaka, Bangladesh S. J. Amith Kumar Department of Mechanical Engineering, J N N College of Engineering, Shivamogga, Karnataka, India Dipjyoti Bora Polymer Petroleum and Coal Chemistry Group, Materials Sciences and Technology Division, CSIR-North East Institute of Science and Technology, Jorhat, Assam, India; Academy of Scientific and Innovative Research, New Delhi, India Ivana Cesarino Department of Bioprocess and Bioengineering, School of Agriculture Sciences, UNESP – São Paulo State University, Botucatu, SP, Brazil Aniruddha Chatterjee Centre for Advanced Materials Research and Technology, Department of Plastic and Polymer Engineering, Maharashtra Institute of Technology, Aurangabad, Maharashtra, India W. S. Chow School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, Nibong Tebal, Penang, Malaysia Allana Arcos Comitre Laboratory of Microbiology and Biochemistry, College of Chemistry and Food Engineering, Federal University of Rio Grande (FURG), Rio Grande, RS, Brazil Jorge Alberto Vieira Costa Laboratory of Biochemical Engineering, College of Chemistry and Food Engineering, Federal University of Rio Grande (FURG), Rio Grande, RS, Brazil

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Contributors

Sruthi Damodaran Department of Biochemistry, Indian Institute of Science, Bangalore, India Michele Greque de Morais Laboratory of Microbiology and Biochemistry, College of Chemistry and Food Engineering, Federal University of Rio Grande (FURG), Rio Grande, RS, Brazil Otavio Dias University of Toronto, Toronto, Canada A. A. Eze Department of Chemical, Metallurgical and Materials Engineering, Institute for NanoEngineering Research (INER), Polymer Technology Unit, Tshwane University of Technology, Pretoria, South Africa Fatirah Fadil School of Industrial Technology, Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM), Shah Alam, Selangor, Malaysia Oladipo Folorunso Department of Electrical Engineering, French South African Institute of Technology (F’SATI), Tshwane University of Technology, Pretoria, South Africa; Centre for Nanostructures and Advanced Materials, DSI-CSIR Nanotechnology Innovation Centre, Council for Scientific and Industrial Research, Pretoria, South Africa Upendra Nath Gupta Polymer Petroleum and Coal Chemistry Group, Materials Sciences and Technology Division, CSIR-North East Institute of Science and Technology, Jorhat, Assam, India; Academy of Scientific and Innovative Research, New Delhi, India Yskandar Hamam Department of Electrical Engineering, French South African Institute of Technology (F’SATI), Tshwane University of Technology, Pretoria, South Africa; École Supérieure d’Ingénieurs en Électrotechnique Et Électronique, Noisy-le-Grand, Paris, France Chinmay Hazra Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal, India Md Enamul Hoque Department of Biomedical Engineering, Military Institute of Science and Technology (MIST), Dhaka, Bangladesh Martin A. Hubbe Department of Forest Biomaterials, North Carolina State University, Raleigh, NC, USA I. D. Ibrahim Department of Chemical, Metallurgical and Materials Engineering, Institute for NanoEngineering Research (INER), Polymer Technology Unit, Tshwane University of Technology, Pretoria, South Africa Mohammad Jawaid Universiti Putra Malaysia, Seri Kembangan, Malaysia Aswathy Jayakumar School of Biosciences, Mahatma Gandhi University, Kottayam, Kerala, India

Contributors

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J. Jayaramudu Polymer Petroleum and Coal Chemistry Group, Materials Sciences and Technology Division, CSIR-North East Institute of Science and Technology, Jorhat, Assam, India; Academy of Scientific and Innovative Research, New Delhi, India Siti Hasnah Kamarudin School of Industrial Technology, Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM), Shah Alam, Selangor, Malaysia Jasila Karayil Department of Chemistry, Government Women’s Polytechnic College, Kozhikode, Kerala, India R. Z. Khoo School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, Nibong Tebal, Penang, Malaysia Ryszard Koslowski Institute of Natural Fibers, Poznan, Poland Debasree Kundu Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal, India Suelen Goettems Kuntzler Laboratory of Microbiology and Biochemistry, College of Chemistry and Food Engineering, Federal University of Rio Grande (FURG), Rio Grande, RS, Brazil W. K. Kupolati Department of Civil Engineering, Institute for NanoEngineering Research (INER), Tshwane University of Technology, Pretoria, South Africa Nathalie Lavoine Department of Forest Biomaterials, North Carolina State University, Raleigh, NC, USA Alcides Lopes Leao Department of Bioprocess and Bioengineering, School of Agriculture Sciences, UNESP – São Paulo State University, Botucatu, SP, Brazil Lucian A. Lucia Department of Forest Biomaterials, North Carolina State University, Raleigh, NC, USA Shiji Mathew School of Biosciences, Mahatma Gandhi University, Kottayam, Kerala, India Juliana Botelho Moreira Laboratory of Microbiology and Biochemistry, College of Chemistry and Food Engineering, Federal University of Rio Grande (FURG), Rio Grande, RS, Brazil Indu C. Nair Department of Biotechnology, SAS SNDP Yogam College, Konni, Pathanamthitta, Kerala, India Mohd Nurazzi Norizan Centre for Defence Foundation Studies, Universiti Pertahanan Nasional Malaysia (UPNM), Kuala Lumpur, Malaysia Emmanuel Emeka Okoro Department of Petroleum Engineering, Covenant University, Ota, Ogun State, Nigeria

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Contributors

Syaiful Osman School of Physics and Materials Studies, Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM), Shah Alam, Selangor, Malaysia Jyotishkumar Parameswaranpillai Materials and Production Engineering, The Sirindhorn International Thai-German Graduate School of Engineering (TGGS), King Mongkut’s University of Technology North Bangkok, Bangkok, Thailand; Department of Mechanical and Process Engineering, The Sirindhorn International Thai-German Graduate School of Engineering (TGGS), King Mongkut’s University of Technology North Bangkok, Bangsue, Bangkok, Thailand; Department of Science, Alliance University, Bengaluru, Karnataka, India Emily V. Piner Department of Forest Biomaterials, North Carolina State University, Raleigh, NC, USA E. K. Radhakrishnan School of Biosciences, Mahatma Gandhi University, Kottayam, Kerala, India Sabarish Radoor Materials and Production Engineering, The Sirindhorn International Thai-German Graduate School of Engineering (TGGS), King Mongkut’s University of Technology North Bangkok, Bangkok, Thailand; Department of Mechanical and Process Engineering, The Sirindhorn International Thai-German Graduate School of Engineering (TGGS), King Mongkut’s University of Technology North Bangkok, Bangsue, Bangkok, Thailand Suprakas Sinha Ray Centre for Nanostructures and Advanced Materials, DSICSIR Nanotechnology Innovation Centre, Council for Scientific and Industrial Research, Pretoria, South Africa; Department of Chemical Sciences, University of Johannesburg, Doornfontein, Johannesburg, South Africa A. Babul Reddy Department of Chemical, Metallurgical and Materials Engineering (Polymer Division), Tshwane University of Technology, Pretoria, South Africa Emmanuel Rotimi Sadiku Department of Chemical, Metallurgical and Materials Engineering, Institute for NanoEngineering Research (INER), Polymer Technology Unit, Tshwane University of Technology, Pretoria, South Africa; Department of Metallurgy, Polymer and Chemical Engineering, Tshwane University of Technology, Pretoria, South Africa Samuel Eshorame Sanni Department of Chemical Engineering, Covenant University, Ota, Ogun State, Nigeria Ajinkya Satdive Centre for Advanced Materials Research and Technology, Department of Plastic and Polymer Engineering, Maharashtra Institute of Technology, Aurangabad, Maharashtra, India

Contributors

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Suchart Siengchin Materials and Production Engineering, The Sirindhorn International Thai-German Graduate School of Engineering (TGGS), King Mongkut’s University of Technology North Bangkok, Bangkok, Thailand; Department of Mechanical and Process Engineering, The Sirindhorn International Thai-German Graduate School of Engineering (TGGS), King Mongkut’s University of Technology North Bangkok, Bangsue, Bangkok, Thailand Saurabh Tayde Centre for Advanced Materials Research and Technology, Department of Plastic and Polymer Engineering, Maharashtra Institute of Technology, Aurangabad, Maharashtra, India Theivasanthi Thirugnanasambandan International Research Centre, Kalasalingam Academy of Research and Education (Deemed University), Krishnankoil, Tamilnadu, India Shyam Tonde Centre for Advanced Materials Research and Technology, Department of Plastic and Polymer Engineering, Maharashtra Institute of Technology, Aurangabad, Maharashtra, India Bruna Pereira Vargas Laboratory of Microbiology and Biochemistry, College of Chemistry and Food Engineering, Federal University of Rio Grande (FURG), Rio Grande, RS, Brazil Sivanjineyulu Veluri Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Łód´z, Poland

Abbreviations

AESO AFM AFNOR AgNPs Al2 O3 AM AMBER APE APP APS ASTM ATH ATR-FTIR B2 O3 BC BET BF BioPBS BMP BNC BPS BRS BSI C/L CaCO3 CAD CCG CES CF CFU CG

Arcylated epoxidized soybean oil Atomic forced microscopy French Association Française de Normalization Silver nanoparticles Aluminum oxide Additive manufacturing Assisted model building with energy reinforcement Aromatic polyesters Ammonium polyphosphate γ -aminopropyl triethoxy silane American Society for Testing Materials Aluminum trihydroxide Attenuated total reflectance spectroscopy Boron oxide Bacterial cellulose Brunauer, Emmett and Teller Banana fiber Bio-based poly(butylene succinate) Biochemical methane potential Bionanocomposites Biodegradable Plastics Society Boiled rice starch British Standards Institute Casting and leaching Calcium carbonate Computerized aided design Chemically converted graphene Committee for Standardization Carbon fiber Colony forming unit Chitosan-functionalized graphene xvii

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CHNF Ch-ZnO CLTE CMC CMNC CMR CNC CNF CNT COMPASS CT DIN DMA DMR DNA DOH DSC DTG Ea EDX EG EM EMF EVOH FAO FDA Fe2 O3 FEM FESEM FGNp FR FTIR FWO G GC GHG GMR GNp GNP GO GOCF GPC GRAS H2 O

Abbreviations

Chitin nanofiber Chitosan-zinc oxide nanocomposites Coefficient of linear thermal expansion Ceramic matrix nanocomposites Ceramic matrix nanocomposites Cumulative measurement respirometer Cellulose nanocrystals Cellulose nanofibers Carbon nanotube Condensed-phase Optimized Molecular Potentials for Atomistic Simulation Studies Computed tomography Deutsches Institut Für Normung Dynamic thermomechanical analysis Direct measurement respirometer Deoxyribonucleic acid Degree of hydration Differential scanning calorimeter Derivative of the thermogravimetry analysis Activation energy Energy dispersive X-ray spectroscopy Expanded graphite Electron microscope Electrolyte membrane fuel cells Ethylene vinyl alcohol Food and Agricultural Organization Federal Drug Administration Ferric oxide Finite element method Field emission scanning electron microscope Functionalization of GNp Flame retardants Fourier transform infrared spectroscopy Flynn–Wall–Ozawa Graphene flakes Gas chromatography Greenhouse gas Gravimetric measurement respirometer Graphene nanoplatelets Graphene/graphite nanoplatelet Graphene oxide Graphene oxide coated curaua fiber Gel permeation chromatography Generally recognized as safe Water

Abbreviations

H2 O2 H3 BO3 HA HDT HNT HPLC HRR ISO JIS LCA LDH LDPE MA MAESO MAPP MBAS MC MD MDS Mg(OH)2 MgO MI MMC MMNC MMT MNP MO MPEG MRI MS MW MWCNT NaCas NBC NC NCC NDIR NFC NFRC NG NIJ NMR NP NR O−

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Hydrogen peroxide Boric acid Hydroxyapatite Heat deflection temperatures Halloysite nanotube High performance liquid chromatography Heat release rate International Organization for Standardization Japanese Industrial Standards Life cycle assessment Layered double hydroxide Low density polyethylene Moisture absorption Methacrylated arcylated epoxidized soybean oil Microencapsulated ammonium polyphosphate Multilayered ballistic armor system Monte Carlo Molecular dynamics Molecular dynamics simulation Magnesium dihydroxide Magnesium oxide Methacryalted isosorbide Metal matrix composites Metal matrix nanocomposites Montmorillonite Magnetic Fe3 O4 nanoparticles Metal oxides Methoxy poly(ethylene glycol) Magnetic resonance imaging Mass spectroscopy Molecular weight Multiwalled carbon nanotube Sodium caseinate Nanobiocomposites Nanocellulose Nanocrystalline cellulose Non-dispersive infrared Nanofibrillated cellulose Natural fiber-reinforced composites Nanographene National Institute of Justice Nuclear magnetic resonance spectroscopy Nanoparticle Natural rubber Superoxide radical

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O2 OBP OH OM OMC OMLS OPA PA PALF PB PBAT PBS PCL PCM PDLA PE PEEK PEO PET PG PHA PHB PLA PLA-C PLA-M PLA-MA PLLA PMC PMNC PNC PO POM POSS PP PS PVA PVC PVDF PVP Rf RGD rGO RNA ROS Rr

Abbreviations

Singlet oxygen Oxygen barrier property Hydroxyl Optical microscopy Organically modified clay Organically modified layered silicate Oil palm ash Polyamide Pineapple leaf fibers Polybutylene Polybutyrate adipate terephthalate Polybutylene succinate Poly(caprolactone) Phase change material Poly(D-lactide) Polyethylene Polyetheretherketone Poly(ethylene oxide) Polyethylene terephthalate Polyglycolide Polyhydroxyalkanoate Poly(3-hydroxybutyrate) Polylactic acid Chloroform Methyl chloride Methylene chloride acetonitrile Poly(L-lactide) Polymer matrix nanocomposites Polymer matrix nanocomposites Polymer nanocomposites Polyolefins Polarized optical microscopy Polyhedral oligomeric silsesquioxane Polypropylene Polystyrene Polyvinyl acetate Polyvinyl chloride Poly(vinylidene fluoride) Poly(vinyl pyrrolidone) Strain fixity Arginylglycylaspartic acid Reduced graphene oxide Ribonucleic acid Reactive oxygen species Strain recovery

Abbreviations

RTM SCNF SEM SiB SiC SiO2 SPM SPNFC SPS Sria/CF-Ep S-SiC STM TBC T cc TCD Td TEM Tg TG TGA THR TiO2 T max T onset TPU TraPPE TTI UNI UP UV VYZ WHO WVP WVT WVTR XG xGNPs XPS XRD ZB ZnO ZnO-NPs ZnO-nr γ

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Resin transfer molding Silanized cellulose nanofiber Scanning electron microscopy Silane-treated banana fiber Silicon carbide Silicon dioxide Scanning probe microscopy Sugar palm nanofibrillated cellulose Sugar palm starch Sansevieria/carbon fiber-reinforced hybrid epoxy Starch-silicon carbide Scanning tunneling microscopy Tributyl citrate Cold-crystallization temperature Thermal conductivity detector End decomposition temperature Transmission electron microscopy Glass transition temperature Mass loss Thermogravimetric analysis Total heat release Titanium oxide Maximum temperature Onset of thermal decomposition temperature Thermoplastic polyurethane Transferable potentials for phase equilibria Time to ignition Italian Ente Nationale Italiano di Unificazione Unsaturated polyester Ultra-violet Vyazovkin World Health Organization Water vapor permeability Water vapor transmission water vapor transmission rate Xanthan gum Exfoliated graphite nanoplatelets X-ray photoelectron spectroscopy X-ray diffraction Zinc borate Zinc oxide Zinc oxide nanoparticles Zinc oxide nanorods Gamma

Morphological Characterization of Bio-nanocomposites Sivanjineyulu Veluri, Dipjyoti Bora, Upendra Nath Gupta, Emmanuel Rotimi Sadiku, A. Babul Reddy, and J. Jayaramudu

Abstract In recent years, with the aid of combining biological/bio-origin molecules with inorganic materials, has been found to be of considerable importance in optical, catalytic, electrochemical and magnetic devices. The materials developed, when combined together are called bio-nanocomposites (BNCs), which are eco-friendly, cost-effective and well-organized components. These materials are of huge interest in various scientific fields, ranging from the electronic industry to medical diagnostics. The use of BNCs in various fields of applications depends on the material morphology, feasibility, compatibility and performance. Consequently, these properties may vary for different BNCs, which may rely on the material composition, development/synthesis methods and crystal structure. The morphology (e.g., dimension and geometric shape) of BNCs has played a significant role in their physico-chemical properties. Therefore, it is very important to know the morphology of the developed BNCs by using microscopic techniques, such as: scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning probe microscopy (SPM), polarized optical microscopy (POM), etc. These techniques are widely used to study the nano-level morphology (e.g., shape, size, orientation, distribution of particles) at the atomic level. Therefore, the present chapter gives a brief information on the modern microscopy techniques for morphological characterization, which plays a very significant role on BNCs.

S. Veluri Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363 Łód´z, Poland D. Bora · U. N. Gupta · J. Jayaramudu (B) Polymer Petroleum and Coal Chemistry Group, Materials Sciences and Technology Division, CSIR-North East Institute of Science and Technology, Jorhat, Assam 785006, India D. Bora · U. N. Gupta Academy of Scientific and Innovative Research, New Delhi 110020, India E. R. Sadiku · A. B. Reddy (B) Department of Chemical, Metallurgical and Materials Engineering (Polymer Division), Tshwane University of Technology, Pretoria, South Africa © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2022 C. Muthukumar et al. (eds.), Polymer Based Bio-nanocomposites, Composites Science and Technology, https://doi.org/10.1007/978-981-16-8578-1_1

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Keywords Bio-nanocomposites · Morphology · SEM · TEM · AFM · STM · POM

1 Introduction Bio-nanocomposites (BNC) are a new class of hybrid materials, comprised of inorganic solids homogeneously dispersed in biopolymers. The term “bionanocomposites” resembles the words “green & eco-friendly”, which refers to renewable as well as biodegradable materials that and exhibit at least one dimension (1D) on the nanometer scale. Such biodegradable materials are evidence of valuable gifts for the present and future generations. According to the Scopus citation database, the number of publications that are related to BNCs, has been growing exponentially every year and it reaches the 19 K articles/publications mark in the year 2020 (see Fig. 1), which indicates a great interest on bio-based and green materials among researchers around the globe. Additionally, these materials are sometimes called “nano-biocomposites, nanocomposites, green composites, eco-friendly composites, bio composites, bio-hybrids or bio-based plastics, etc. The synthesis and characterization of materials play a significant role in material science & engineering technology and hence, in BNCs materials as well. Nanoparticles/nanofillers occur in different shapes and sizes, which in turn, rely on different synthetic methodologies. Therefore, the synthesized nanostructured materials displaying various morphologies, such as nanoparticles (Piekarska et al. 2017),

Fig. 1 Number of publications per year according to scopus up to october 2020. Keywords for search: bionanocomposites, biocomposites

Morphological Characterization of Bio-nanocomposites

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nanotubes (Chen et al. 2018), nanoflowers (Farbod and Mazloum-Ardakani 2019), nanocubes (Zhang et al. 2018), etc., have been widely studied and have shown critical technological values in numerous applications (Mayeen et al. 2018). The synthesis of nanostructured materials (e.g., BNCs) with certain physical and functional properties is important for modern materials sciences and engineering technologies. There is an increasing awareness in the field of BNCs, owing to their promising physical and functional properties and these materials have enthused, in recent years, an excessive deal of interactions among biologists, engineers, physicists and chemists. In order to understand the effect/use of these nanoparticles/nanomaterials and their influence on nanotechnology or nanoscience, a detailed morphological study regarding the structure, distribution of these nanostructures was required (Idumah and Obele 2021; Sanusi et al. 2020). The featured morphological characterization imparts on the information regarding the morphology of the different phases, chemical composition and crystallographic deficiencies (Sivanjineyulu et al. 2018). Numerous properties of nanomaterials can remarkably be modified, based on their morphology, therefore, a detailed study on the morphology of nanomaterials and their effect on: electrical, electronic, optical, magnetic, physical and thermal properties is required. In addition, microstructural details of nanomaterials, ranging from a few Å to 100 nm (nm) level, can be evaluated by using various microscopic techniques. Several microscopic techniques, amongst which are: Electron Microscopy (EM), Optical Microscopy (OM) and Scanning Probe Microscopy (SPM), play key roles in the characterization of BNCs morphology on various length scales. The resolution power of the various microscopic techniques, is clearly depicted in Table 1. It can be, observed that microscopic techniques retain a central position among all those modern nano-scale characterization methods/techniques, which implies that Table 1 Resolution of numerous microscopic techniques Size

0.1nm 1nm

Microscopic techniques with magnification

10nm

100nm

1μm

10μm

100μm

OM (10-100x) SEM (1,000x) FESEM (100,000x) TEM (100,000x) STM/SFM (10,000,000x)

1mm

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these techniques play important roles in order to elucidate the internal morphology and structure–property correlation of nanocomposites. Furthermore, the utmost influence of the microscopic techniques in the expansion of nanocomposites science and technology can be realized by the fact that almost all of the scientific literature devoted to BNCs, make a direct or an indirect reference to the use of these techniques. Thus, these techniques can play a vital role, especially in the optimization of material properties through structural characterization, which offers direct hints, not only about the structure of the guest itself, but also about the adhesion between host–guest-matrix, filler distribution/dispersion and the influence of the filler on the morphology and properties of the embedding host matrix. The literature shows that recently, with the help of various EM techniques, many researchers have investigated the morphology of BNCs (Khelifa et al. 2019; Wu and Qiao 2021). Predominantly, the encouraging results of electron tomography and low voltage experimental techniques, offer valuable information about the adhesion and distribution of filler within the matrix. However, the aim of this chapter is to elucidate the importance of the various EM and OM techniques, in the study of the morphological characteristics of some selected BNCs. Different morphological characterization methods, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), etc., have also been used to evaluate the particles/fillers in the nano regime. A detailed description of the different types of microscopic techniques, used for morphological study of the BNCs, is presented in this book chapter.

2 Electron Microscope (EM) Electron microscopes (EMs) differ from light microscopes in that they create an image of a substance by using a beam of electrons rather than a beam of light. Therefore, it leads to the identification of the substance at atomic resolution. This is due the fact that the electrons have a considerably shorter wavelength than the visible light and this permits EMs to generate high-resolution images than the standard light microscopes (Leng 2009; von Heimendahl et al. 1980). EMs can be, used to analyze, not just the whole specimen, but also the internal structures and molecules within them. Modern EMs can magnify a substance up to 2 million times and they are still built upon the Ruska’s prototype and the correlation between wavelength and resolution (Goodhew and Humphreys 2000). However, EM accompanied by other techniques, has played a vital role in the analysis of the morphology and structure–property correlations of materials. EM identifies the structure and properties of particular locations of a material and information is not limited to the average values (Adhikari and Michler 2009). The importance of EM in nanoscience and technology, rises predominantly for two reasons. Firstly, the information from EM is significantly, more vital than that from other sources. The morphology of polymer matrix as well as of the filler and the interaction between them can be concurrently evaluated within the nanometer scale by using an EM. Secondly, EM allows for the

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analysis of the response of all structural details of the materials towards an applied load, supporting the design of tailored materials. EM is the only technique, which provides very direct evidence of intercalation and exfoliation of the filler within the matrix, permitting a direct quantification of the morphological features of the bio-nanocomposites (Adhikari and Michler 2009). Usually, two different kinds of EMs are used to study the morphological characterization, which includes scanning electron microscopy (SEM) and transmission electron microscopy (TEM) (Flegler et al. 1993). In both techniques, the electron beams fall on the surface of the sample. In the SEM technique, the electron will directly interact only with the sample surface, which leads to providing information only about the surface of the sample and in contrast, the TEM measures the changes in the electron beam, scattered within the sample (Mayeen et al. 2018). The detailed studies about these two techniques are, discussed below.

2.1 Scanning Electron Microscopy (SEM) SEM is a surface analytical technique, in which, centered beam of energetic electrons scans in a raster scan pattern on the sample’s surface. The interaction between the energetic electron signals and the scanned specimen is, determined by the hastening rate of the incident electrons, which carry a considerable amount of kinetic energy. SEM is capable of resolution, ranging between 10 μm to 10 nm and it is one of the most reliable characterization techniques, often used to analyze the structure and surface properties and the specific locations of micro/nano polymers/particles on the various length scales. Additionally, SEM images appear in a three dimensional format, due to its having a large field of depth. However, SEM offers only information on whether the filler or particles are, dispersed uniformly over a large volume of the material. The literature sourced, refers to the fact that SEM is often used as a routine technique for the estimation of filler or particle distribution within the polymer matrix in BNCs (Amelinckx et al. 1996; Brandon and Kaplan 2008; Shindo and Oikawa 2002). Additionally, the SEM imaging is, carried out in three important signal modes, which are the backscattered electron (BSE) mode, secondary electron (SE) mode and X-ray mode. Often, there are two types of interactions, viz: elastic and inelastic interactions that can possibly occur during an examination. The elastic interaction happens when the primary deflection of the electron beam interacts with the samples of atomic electrons or the nucleus with relevant energy. During the elastic interaction, high energy BSEs are emitted from the substance depth of >1 μm. The deflection of the primary electrons scattered the angle at >90° and provide compositional contrast, which depends on the atomic number of the elements involved in the interaction to be used in samples imaging. On the other hand, the secondary electrons (SEs) are low-energy scattered electrons, which are emitted from the sample surface after being bombarded with the primary electron beam, where energy transformation will

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occur to the atom within the sample. The SEs are initially used for topography imaging of the samples (Abd Mutalib et al. 2017). In the SEM imaging process, the SE mode is the most common type of signal used. During the SEM imaging, a few nanometers of the sample surface can be detected due to the relatively low energy of the incident electrons. Therefore, the SE is comparatively accurate for the generation of the topological contrast of the sample, such as the surface roughness and texture. It is noteworthy to emphasize the fact that only the SEs reach the detector in order to generate the image with a dark contrast. Furthermore, it will accurately depict the comprehensive topographic information of the sample when the SEs (which are produced by low voltage electron in the primary beam) are from the utmost surface of the sample. The BSE mode of scanning comprises the detection of an incident electron with energy greater than 50 eV. The directional change of electrons will happen when the elastic collision of the electron at higher than 90°, results in almost half of the electrons bouncing back to the direction of the source and holding most of its initial energy (Egerton 2005). Usually, higher atomic number elements will deflect higher electrons due to a higher number of positive ions on its nucleus. For example, Gold (Au) with high atomic number, possesses ~50% of BSE yield, whereas Carbon (C) possesses a 6% yield due to a lower atomic number. Therefore, the BSE yields depend on the percentage of the reflected electrons generated by the sample. Finally, it is concluded that BSE electrons carry noticeable information regarding the structures under the surface of the samples.

2.1.1

Scanning Electron Microscopy for BNCs

A standard specimen for the SEM examination is a cryo-fractured surface of BNCs material. Additionally, a flat surface of the specimen can also be prepared by means of microtomy technique. Occasionally the specimens for SEM examination are prepared by etching with a suitable chemical on the fractured surface of the sample. Prior to the SEM examination, the specimens prepared (Figs. 2 and 3), often allow being coated with a thin conducting material, such as: carbon, platinum, silver, palladium, iridium, tungsten or gold sputter in order to avoid charging (Sivanjineyulu et al. 2017) and to improve conductivity. Figure 2 shows the SEM (BSE mode) images of the fractured surfaces of selected samples. The surface for the SEM imaging was prepared by cryogenically fracturing the sample after immersion of samples in liquid nitrogen for ~3 min. The changes in the phase morphology of poly(butylene succinate) (PBS) and polypropylene (PP) polymer phases after the addition of maleated PP (PPgMA), carbon nanotube (CNT), and Cloisite® 15A (C15A), can be easily identified as shown in Fig. 2. With the addition of 0.5 wt% and 3 wt% of CNT, the domain phase of PBS drastically reduced and no preferential localization of CNT was observed as shown in Fig. 2c, d. After the inclusion of sole C15A in the nanocomposites, the biodegradable PBS became evident and developed a quasi-co-continuous phase morphology, as illustrated in Fig. 2e. Figure 2f depicts the simultaneously added CNT/C15A into the nanocomposites and the significantly reduced domain phase was, observed

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Fig. 2 SEM fractured surfaces of represented samples: a PBS/PP, b PBS/PPGMA/PP, c 0.5 wt%, d 3 wt% of CNT, e 1 wt% clay (C15A) and f 1 wt% of each CNT and C15A in PBS/PPGMA/PP nanocomposites (Sivanjineyulu et al. 2017) (Reproduced with permission from Elsevier)

as well. Figure 3 illustrates the surface fractured and chemically etched, by using chloroform on the various samples. The specimens were treated with chloroform in order to etch out the biodegradable PBS phase from the matrix phase and was goldsputtered, prior to the examination. The filler dispersion and domain phase alteration can be, observed in Fig. 3.

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Fig. 3 SEM fractured surface of chloroform etched samples: a PBS/PPGMA/PP, b 2 wt% of CNT and c 1 wt% of each CNT and 15A in PBS/PPGMA/PP nanocomposites (Sivanjineyulu et al. 2017) (Reproduced with permission from Elsevier)

2.2 Field Emission Scanning Electron Microscopy (FESEM) FESEM provides a topographical image with elemental evidence at magnifications of between 10x and 100,000x with an unlimited depth of field, which also delivers clearer, less electrostatically distorted images with a spatial resolution in similar mode when compared to images provided by the conventional SEM, as illustrated in Fig. 4 (Sivanjineyulu et al. 2018). In Fig. 4a, b the dispersion status of the welldistributed CNTs throughout the PBS matrix phase and a minor amount of CNTs traces in the polylactide (PLA) domain phase as well, can be clearly seen. Figure 4c depicts the dispersion of sole 15A within the PLA domain phase, but not in the PBS phase. Both CNTs and 15A were, found selectively in different phases, as shown in Fig. 4d. This is, attributed to the fact that the CNTs were favored to locate in the PBS phase, whereas the 15A inclusion was favored for localization within the PLA domain phase, consequently an altered phase morphology occurred in BNCs. However, the typical working principles for the FESEM are the same as the conventional SEM, with the exception of employing a field emission electron source (Brodusch et al. 2017; Crewe 1966; Crewe et al. 1968). Additionally, SEM uses a thermionic electron source, whereas FESEM relies on a potential gradient to emit energetic electron beams. The field emission gun in the FESEM instrument, contains a specific tungsten filament with a sharp-pointed tip and this sharp tip is, used as the main electron source for FESEM. The electron probe, as small as 0.5 nm in FESEM, allows for a higher image resolution than in the conventional SEM. Moreover, the additional advantage of FESEM is that the surface topographic images with a high resolution, can also be generated at low acceleration voltage (10–9 Torr) during

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operation in order to ensure the stability of electron and inhibit cathode contamination as well. However, the field emission gun electron sources in FESEM, also endure low beam current stability (Reimer 1998). The chemical elements, which are mostly present on the sample surface, can be, detected by using standard energy dispersive X-ray spectroscopy (EDX), equipped in the FESEM. FESEM has the potential to analyze small area contamination spots, at electron accelerating voltages well-paired with EDX spectroscopy (Goldstein et al. 2018). EDX spectroscopy contributes to the detection of the elemental composition of a substance by utilizing the SEM. The application of the standard operating EDX spectroscopy, includes the evaluation and identification of material, identification of contaminants, spot detection analysis, screening of quality control, etc. Upon collision with the electron beam in an electron microscope, the samples interact with the beam and generate characteristic X-rays. Owing to the principle that none of the elements have the same X-ray emission spectrum, they can be varied and quantified for their concentration in the sample. The X-ray is the result of the interaction of the primary electron beam with the nucleus of the specimen atom. For instance, The EDX spectroscopy can detect silicon element (Si), which is a constituent of the layered silicate clay, abundantly present in the scanned area between the constituents of the polymer and the coating material, as shown in Fig. 4c, d (Sivanjineyulu et al. 2018).

2.2.1

Limitations

Usually, the SEM instrument is very large and requires a very special room without any magnetic, electric and vibration interference. The chamber size should be carefully considered before starting the analysis of the sample, where the water must be in a few inches’ diameter can be used. For example, if the large size samples are to be analyzed, then a large chamber size SEM is required. Another important limitation is that the secondary electrons, which are produced by the interaction between the sample and the primary electrons, can generate the image in SEM, which does not lead to the production of secondary electrons for very thin samples. In addition, a clean sample is mandatory for getting a high-quality image and for cleaning purposes, a buffer or distilled water is used in an ultrasonic bath.

2.3 Transmission Electron Microscopy (TEM) The transmission electron microscopy (TEM) is a highly sophisticated instrument that was developed, many years ago and has been used in many scientific disciplines. For instance, TEM was broadly, used for material characterization during World War—II. However, TEM is an essential instrument, designed for researchers who are interested in the understanding of the morphological properties of nanostructured materials and employing the performance of such materials, because the instrument

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Fig. 5 Modern transmission electron microscopy instrument and electron diffraction pattern

has the incomparable capability to deliver structural and chemical compositions at the nanoscale. The optical microscopy (OM) resolution is limited to the visible light wavelength region, hence, resulting in preventing atomic-scale imaging. Whereas, the TEM relies on electrons, which have a wavelength of less than 1 Å (where 1 Å = 10–10 m), hence, high-resolution images will be achieved. Additionally, the TEM instrument can afford considerably large magnifications, it is up to 50 million times or more, which makes the morphological feature visibility, even easier. Usually, image formation in TEM is further more complex when compared to optical microscopy (see the subsequent section). This might be due to the electrons taking a spiral trajectory by using the strong magnetic fields that are required for bombarding the electron beam. Due to unavoidable aberrations of the electron lenses, the performance of the microscope was limited. In order to overcome these, there is the need to compromise between small-angle diffraction effects and wide-angle spherical aberration boundaries and the resolution, d can be, approximately expressed by the following equation: 1/4

d = A CS λ3/4 where ‘A’ is a constant value between 0.43 and 0.7 and it depends, completely, on the nature of the imaging (e.g., coherent, incoherent, or phase contrast) (Wang 2001), Cs is the spherical aberration coefficient of the matter lens, λ is the electron wavelength. The values of d, typically ranges between 3.0 and 1.0 Å, as a result of the electron energies increasing from 100 to 1250 keV. An example of a modern TEM and electron

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diffraction, is shown in Fig. 5, which operates at either 200 or 300 keV and has its resolution, restricted to < 2.0 Å, which is identical to the gap between atoms.

2.4 TEM Imaging 2.4.1

Standard Operating Mode

In the standard operating mode, only a small fraction of electrons pass through the material and form a highly magnified image, which is commonly referred to as amplitude or diffraction-contrast imaging. Most of the scattered or diffracted electrons are prohibited by a small objective aperture (it serves to determine the image contrast), which is located in the back focal plane of the objective lens. In here, the diffraction pattern takes place according to the Bragg’s law; wherein the incident beam passes through the crystal lattice and diffraction occurs. Thus, it is easy to find the crystallographic orientation of the materials by using the diffraction patterns and the zone axis. Due to these conditions, many common structural defects are highly noticeable. If the electron diffraction pattern of the reference, material can be calibrated, which then makes it easy to find the spacing and angles between two crystalline planes (Wang 2000).

2.4.2

High-Resolution Operating Mode

Figure 6 shows a schematic illustration of the constituents of a TEM. As seen in Fig. 6, the electron gun is accelerated by means of the application of a high voltage ranging between 200 and 400 kV, following which, electrons are, emitted. The direction, size and diameters of the electron beam are controlled by the use of numerous types of lenses (such as condenser, objective and projector lens). In general, condenser lenses are used to focus the electron beam onto the sample, which then, interacts with the sample and produces secondary particles. Among the various secondary particles, diffracted and emitted electrons are important, which in turn, generate the diffraction and imaging modes of TEM. Furthermore, the diffraction mode plays an important role in TEM, since it can give information with regards to the structure, lattice parameters and structural properties (Reimer 1989). The diffracted beam is then focused by an objective lens, followed by a projector lens and the electrons are detected by the sensor, resulting in a spot pattern, as shown in Fig. 6. Whereas, in the case of the transmitted mode, the transmitted electrons are collected from the bottom of the sample and generate three types of imaging fields, which are, bright field, darkfield and high-resolution electron microscopy. In the bright field microscopy, the transmitted electrons produce contrast due to the structural defects in the sample; this might be due to the fact that there were, the scattering and diffraction from specific areas of the sample (Russell and Edington 1977). The high-resolution transmission electron modes involve two types of electrons, which are transmitted and diffracted electrons. The combination of these two phenomena at a certain point, produces an

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Fig. 6 Schematic diagram of transmission electron microscopy

image, in such a way that their amplitude and phase are, conserved. This mode is generally the most important and the broadly used in nano-research, owing to the fact that this mode generates an image resolution up to 0.2 nm.

2.4.3

Transmission Electron Microscopy for BNCs

A modern TEM technique provides valuable information about the particle size, inner structure and arrangement of crystals, morphology and the stress state of materials, e.g., BNCs. The transmitted electrons pass through the bionanocomposite material, generating an image (as seen in Fig. 7), which is the usefulness of the TEM. For instance, Piekarska et. al. (Piekarska et al. 2016) employed TEM micrographs of the PLA/organoclay (MMT) and PLA/MMT/cellulose nanofiber (CF) of hybrid BNCs to delineate the dispersion status of MMT platelets within the biodegradable PLA matrix, as shown in Fig. 7a, b. They concluded from the TEM images that the exfoliation of MMT platelets within the matrix is evident and furthermore, the exfoliation or intercalation of the MMT platelets was observed with the inclusion of CF in the BNCs. HRTEM also gives valuable information regarding the inner structure of the BNCs. Ekambaram and Doraisamy (Ekambaram and Doraisamy 2017) performed a high-resolution TEM procedure for carboxymethyl chitosan (CMC) and zinc oxide (ZnO) biodegradable nanocomposites and they found that ZnO was entrapped as

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Fig. 7 Transmission electron microscopy of: a PLA/MMT and b PLA/MMT/CF BNCs (Piekarska et al. 2016) (Reproduced with permission from Elsevier)

nanoparticles within CMC, forming CMC/ZnO BNCs, as illustrated in Fig. 8. In addition, they revealed that the nanocomposite formed was predominantly tubular in structure and the average diameter of the preferentially oriented ZnO was between 78 and 91 nm and the encircling layer of CMC was between 25 and 48 nm thick. Kumar et al. (Kumar et al. 2021) fabricated polyphenylsulfone (PPS)/cellulose acetate (CA) derivatives of hollow fiber membranes, filled with binary ZnO and magnesium oxide (MgO) for the decontamination of arsenic from drinking water. They employed the HR-TEM to study the morphology and dispersion status of ZnO and MgO nanoparticles within the PPS/CA composites, as depicted in Fig. 9. A small amount of ZnOMgO in ethanol solution was distributed and sonicated for 30 min in order to obtain a homogeneous blend solution. The solution was distributed over a copper grid and then, an incandescent lamp was employed to dry the copper grid for 24 h. Figure 9a–e demonstrates the HR-TEM of the dispersed ZnO-MgO particles and Fig. 9f shows

Fig. 8 High-resolution TEM images of CMC-ZnO bionanocomposites. (Ekambaram and Doraisamy 2017) (Reproduced with permission from Elsevier)

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Fig. 9 a to e: HR-TEM images and f SAED pattern of ZnO-MgO nanoparticles. (Kumar et al. 2021) (Reproduced with permission from Elsevier)

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the selected area for electron diffraction (SAED) profile of ZnO-MgO. Figure 9a–d shows that the nanosized and aggregated ZnO-MgO nanoparticles were evidenced, attributing this phenomenon to the fact that a significant agglomeration occurred due to the improper sonication of ZnO-MgO in the ethanol solution. The ultralight thin film of MgO was, decorated on ZnO particles, with sphere-like structure. From Fig. 9e, lattice projections were, exhibited and the lattice distance between one another was maintained at ~0.281 nm. The ZnO-MgO nanoparticle used, displayed an increased surface area-to-volume ratio by exhibiting crystalline and ferromagnetism behaviors from the fresh ZnO-MgO nanoparticle. From the results of the HR-TEM experiment, they also identified the crystalline structure of ZnO-MgO nanoparticles due to the presence of bright rings and spots.

2.4.4

Limitations

The sample preparation in TEM has played a significant role and subsequently, the quality of the output, strongly relies on the quality of the sample and its preparation for analysis. The ideal sample preparation for TEM studies must be, followed, since the sample must be small, very thin (10–100 nm) and stable in ionization radiation. The thinning of sample can be achieved by cutting/graining and the electron transparency can be improved by various methods. Thick samples are difficult to analyze with TEM due to the resultant poor transmitted electrons, passing through the sample. In addition, transmitted electrons must be strong in order to generate an image on the screen or photographic plate. The thickness of the sample can be calculated by using accelerated voltage and the average atomic number of the sample. It is strongly recommended that the thickness of the specimen must be