Frontiers of textile materials: polymers, nanomaterials, enzymes, and advanced modification techniques 9781119620365, 1119620368, 9781119620396, 1119620392, 9781119620419, 1119620414

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Frontiers of Textile Materials

Scrivener Publishing 100 Cummings Center, Suite 541J Beverly, MA 01915-6106 Publishers at Scrivener Martin Scrivener ([email protected]) Phillip Carmical ([email protected])

Frontiers of Textile Materials Polymers, Nanomaterials, Enzymes, and Advanced Modification Techniques

Edited by

Mohd Shabbir, Shakeel Ahmed and Javed N. Sheikh

This edition first published 2020 by John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, USA and Scrivener Publishing LLC, 100 Cummings Center, Suite 541J, Beverly, MA 01915, USA © 2020 Scrivener Publishing LLC For more information about Scrivener publications please visit www.scrivenerpublishing.com. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, except as permitted by law. Advice on how to obtain permission to reuse material from this title is available at http://www.wiley.com/go/permissions. Wiley Global Headquarters 111 River Street, Hoboken, NJ 07030, USA For details of our global editorial offices, customer services, and more information about Wiley products visit us at www.wiley.com. Limit of Liability/Disclaimer of Warranty While the publisher and authors have used their best efforts in preparing this work, they make no rep­ resentations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation any implied warranties of merchant-­ ability or fitness for a particular purpose. No warranty may be created or extended by sales representa­ tives, written sales materials, or promotional statements for this work. The fact that an organization, website, or product is referred to in this work as a citation and/or potential source of further informa­ tion does not mean that the publisher and authors endorse the information or services the organiza­ tion, website, or product may provide or recommendations it may make. This work is sold with the understanding that the publisher is not engaged in rendering professional services. The advice and strategies contained herein may not be suitable for your situation. You should consult with a specialist where appropriate. Neither the publisher nor authors shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages. Further, readers should be aware that websites listed in this work may have changed or disappeared between when this work was written and when it is read. Library of Congress Cataloging-in-Publication Data ISBN 978-1-119-62037-2 Cover image: Pixabay.Com Cover design by Russell Richardson Set in size of 11pt and Minion Pro by Manila Typesetting Company, Makati, Philippines Printed in the USA 10 9 8 7 6 5 4 3 2 1

Contents Preface xv 1 Introduction to Textiles and Finishing Materials Mohd Shabbir and Javed N. Sheikh 1.1 Introduction 1.2 Polymers 1.3 Nanomaterials 1.4 Enzymes 1.5 Plasma and Radiations for Textiles 1.6 Flexible Electronics References

1

2 Polymers for Textile Production Mohammad Tajul Islam, Md. Mostafizur Rahman and Nur-Us-Shafa Mazumder 2.1 Polymers 2.2 History of Polymer 2.3 Classification of Polymers 2.4 Polymerization 2.4.1 Chain Polymerization 2.4.2 Step Polymerization 2.5 Polymers in Textile Fibers 2.5.1 Natural Polymers 2.5.1.1 Cellulose 2.5.1.2 Cotton 2.5.1.3 Jute 2.5.1.4 Keratin 2.5.1.5 Wool 2.5.1.6 Fibroin 2.5.1.7 Silk 2.5.2 Synthetic Polymers 2.5.2.1 Polyethylene

13

1 2 3 4 6 7 8

13 15 16 19 19 21 23 24 24 25 26 26 27 28 28 29 29 v

vi  Contents 2.5.2.2 Polypropylene 2.5.2.3 Polytetrafluoroethylene 2.5.2.4 Poly Vinyl Chloride 2.5.2.5 Poly Vinylidene Chloride 2.5.2.6 Polyamide 2.5.2.7 Polyethylene Terephthalate 2.5.2.8 Polyacrylonitrile 2.5.2.9 Modacrylic Fiber 2.5.2.10 Spandex Fiber 2.6 Polymers in Textile Processing 2.6.1 Polyvinyl Alcohol 2.6.2 Starch 2.6.3 Sodium Alginate 2.7 Conclusion References 3 Advances in Polymer Coating for Functional Finishing of Textiles Asma Bouasria, Ayoub Nadi, Aicha Boukhriss, Hassan Hannache, Omar Cherkaoui and Said Gmouh 3.1 Introduction 3.2 Polymer Coating Methods 3.2.1 Dip Coating 3.2.2 Transfer Coating 3.2.3 Kiss Roll Coating 3.2.4 Gravure Roll Coating 3.2.5 Slot Die or Extrusion Coating 3.2.6 Powder Coating 3.2.7 Knife Coating 3.2.7.1 Choice of the Thickness 3.2.7.2 The Viscosity 3.2.7.3 Drying 3.2.7.4 Type of Knife 3.2.7.5 Knife Use Technologies 3.2.7.6 Type of Knife Coating 3.3 New Technologies in Polymer Coatings 3.3.1 Plasma Treatment Technology 3.3.2 Electrofluidodynamic Treatment Technology 3.3.3 Supercritical Carbon Dioxide-Based Method Technology 3.4 Coating Materials 3.4.1 Polyvinylchloride (PVC)

33 36 38 40 41 47 50 52 52 54 54 56 56 57 57 61 62 63 63 64 64 64 65 65 66 67 67 67 68 69 70 71 71 72 73 73 74

Contents  vii 3.4.2 Polyacrylics (PA) 3.4.3 Polyurethane (PU) 3.5 New Functionalities of Polymer Coatings 3.5.1 Application in Smart Textile 3.5.2 Flame Retardant 3.5.3 Water Repellence 3.5.4 Antibacterial Function 3.6 Conclusions and Future Outlook References 4 Functional Finishing of Textiles with β-Cyclodextrin Aminoddin Haji 4.1 Introduction 4.2 Properties of Cyclodextrins 4.3 Chemical Modification of Cyclodextrins 4.4 Methods for Attachment of β-CD on Textiles 4.5 Functional Properties Obtained by Attachment of β-CD on Textiles 4.5.1 Antimicrobial Activity and Drug Delivery 4.5.2 Fragrance Release and Anti-Odor Finishing 4.5.3 Improved Dyeing and Printing 4.5.4 Wastewater Treatment 4.5.5 Flame Retardant Finishing 4.6 Conclusion References 5 Synthesis of Nanomaterials and Their Applications in Textile Industry Rizwan Arif , Sapana Jadoun and Anurakshee Verma 5.1 Introduction 5.2 Synthesis of Nanomaterials 5.2.1 Preparation of Chitosan Nano-Fibers 5.2.2 Preparation of Polyethylene Glycol Capped Silver Nanoparticles (AgNPs) 5.2.3 Preparation of Silk Textile Nano-Composite Materials of TiO2 Nanoparticles 5.3 Synthesis of Nano-Fiber-Based Hydrogels (NFHGs) 5.3.1 Electrospinning 5.3.2 Weaving 5.3.3 Freeze Drying 5.3.4 3D Printing 5.4 Application of Nano Textiles

74 75 77 77 77 79 81 82 82 87 87 89 91 91 100 100 101 105 105 105 109 109 117 118 119 119 120 122 122 123 123 124 124 124

viii  Contents 5.5 Conclusion References

130 131

6 Modification of Textiles via Nanomaterials and Their Applications 135 Sapana Jadoun, Anurakshee Verma and Rizwan Arif 6.1 Introduction 136 6.2 Nanotextiles and Its Properties 137 6.3 Modification of Textiles via Nanoparticles 138 6.3.1 Modification via Silver Nanoparticle 139 6.3.2 Modification via Zinc Oxide Nanoparticle 143 6.3.3 Modification via Titanium Dioxide Nanoparticle 144 6.3.4 Modification via Magnesium Oxide (MgO) Nanoparticles 144 6.3.5 Modification via Polymer Nanoparticles 146 6.4 Applications 146 6.5 Conclusion 147 References 148 7 UV Protection via Nanomaterials Kunal Singha, Subhankar Maity and Pintu Pandit 7.1 Introduction 7.1.1 Different Types of Nano-Finishing on Textile Materials 7.1.1.1 UV Protection 7.1.1.2 Nano-Silver (Ag) (Antimicrobial Activity) 7.1.1.3 Water Repellence Finishing 7.1.1.4 Self-Cleaning or “Lotus Effect” 7.1.1.5 New-Age Nano-Finishing on Textile Materials Nano-Care 7.2 Zinc Oxide Particle (ZnO) Physical Properties 7.2.1 Chemical Properties 7.2.2 Nanophase ZnO 7.2.3 TiO2 Structure and Properties 7.2.3.1 TiO2 Nanoparticle 7.3 UV Protective Applications 7.3.1 Nanocoating of ZnO–TiO2 on Textile Fabric 7.3.2 Polymer Dispersion Methods of Nanocoating 7.4 Applications as UV Absorber and Sunscreen 7.4.1 Nanomaterials Used in UV Protective Finishing 7.5 Nano-ZnO-TiO2 Finishing 7.5.1 Mechanism of UV Protection

153 154 154 154 155 155 155 156 156 156 157 157 157 157 158 158 159 159 161 162

Contents  ix 7.5.2 UV Protection Through Nano-Finishing of Textiles 7.6 Evaluation of UV Protection Finishes 7.7 Conclusions References

162 163 164 165

8 Synthesis, Characterization, and Application of Modified Textile Nanomaterials 167 Anurakshee Verma, Rizwan Arif and Sapana Jadoun 8.1 Introduction of Textile Nanomaterials 167 8.2 Synthesis of Textiles Nanomaterials 168 8.2.1 Synthesis via Hydrothermal Method 169 8.2.2 Synthesis via Solvo-Thermal Method 169 8.2.3 Synthesis via Chemical Vapor Deposition (CVD) Method 169 8.2.4 Synthesis via Physical Vapor Deposition (PVD) Method 170 8.2.5 Synthesis via Template Method 170 8.2.6 Synthesis via Conventional Sol–Gel Method 170 8.2.7 Synthesis via Microwave Method 170 8.2.8 Synthesis via Fabrication Process 170 8.3 Characterization 171 8.3.1 Microscopic Characterization of Textile Nanomaterials 172 8.3.1.1 Transmission Electron Microscopy (TEM) 172 8.3.1.2 Atomic Force Microscope (AFM) 172 8.3.1.3 Scanning Electron Microscopy (SEM) 173 8.3.1.4 Scanning Tunneling Microscopy (STM) 174 8.3.2 Spectroscopic Characterization of Textile Nanomaterials 175 8.3.2.1 Ultraviolet-Visible (UV-VIS) Spectroscopy 175 8.3.2.2 Raman Spectroscopy 175 8.3.2.3 Infrared Spectroscopy (IR) 175 8.3.3 Characterization of Textile Nanomaterials by X-Ray 176 8.3.3.1 Energy Dispersive X-Ray Analysis (EDX) 176 8.3.3.2 Wide Angle X-Ray Diffraction 176 8.3.3.3 X-Ray Photoelectron Spectroscopy (XPS) 176 8.3.3.4 Particle Size Analyzer 177 8.3.4 Characterization of Textile Nanomaterial by Some Other Technique 178 8.3.4.1 Physical Testing 178

x  Contents 8.3.4.2 Determination of Recovery Angle and Tensile Properties 178 8.3.4.3 Determination of Absorbency by Wicking Test and Bending Length 179 8.3.4.4 Evaluation of Water and Air Permeability 179 8.4 Application of Textiles Nanomaterials 179 8.4.1 Application Based on Properties of Textile Material 179 8.4.1.1 Anti-Bacterial Properties of Textile Nanomaterial 179 8.4.1.2 UV Protective Properties of Textile Nanomaterial 180 8.4.1.3 Water Repellence Properties of Textile Nanomaterial 180 8.4.1.4 Anti-Static Properties of Textile Nanomaterial 180 8.4.1.5 Flame Retardant Properties of Textile Nanomaterial 180 8.4.1.6 Wrinkle-Free Properties of Textile Nanomaterial 181 8.4.1.7 Self-Cleaning Properties of Textile Nanomaterial 181 8.4.1.8 Economical and Environmental Aspects of Textile Nanomaterial 181 8.4.2 Application in Textile Industry 182 8.4.2.1 Textile Nanomaterial Used in Swimming Costume 182 8.4.2.2 Textile Nanomaterial Used in Sports Goods 182 8.4.2.3 Textile Nanomaterial Used Inflexible Electronic Circuit 182 8.4.2.4 Textile Nanomaterial Used in Lifestyle 182 8.5 Current Trends and Future Prospects 183 8.6 Conclusion 183 References 184 9 Biomaterials-Based Nanogenerator: Futuristic Solution for Integration Into Smart Textiles S. Wazed Ali, Satyaranjan Bairagi and Pramod Shankar 9.1 Introduction 9.2 Biomaterial-Based Piezoelectric Nanogenerator 9.2.1 Cellulose-Based

189 190 191 191

Contents  xi 9.2.2 Collagen-Based 9.2.3 Protein-Based 9.3 Conclusion Acknowledgment References 10 Textiles in Solar Cell Applications Khursheed Ahmad 10.1 Introduction 10.2 Basic Principle and Types of Solar Cells 10.3 Textiles in Solar Cells 10.3.1 Textiles in Perovskite Solar Cells 10.3.2 Textiles in Dye Sensitized Solar Cells 10.4 Conclusion References

194 197 198 199 199 203 203 205 206 206 210 212 213

11 Multifunctionalizations of Textile Materials Highlighted by Unconventional Dyeing 219 Vasilica Popescu 11.1 Introduction 220 11.2 Functionalization of Textile Materials: Functionalization Techniques 220 11.3 PAN: Functionalization/Multifunctionalization by Chemical Treatments 223 11.3.1 Dyeing of Functionalized Acrylic Fibers with Different Reagents 229 11.3.2 Functionalization of PAN-M with Basic Reagents 230 11.3.3 Dyeing of PAN-M Functionalized with Basic Reagents 238 11.4 Multi-Functionalization of Acrylic Fiber by Grafting with Polyfunctional Agents 244 11.4.1 Multifunctionalization of PAN Fiber with Chitosan 244 11.4.1.1 Multifunctionalization of PAN-M Fiber with Chitosan by Means of Electrostatical Bonding 245 11.4.1.2 Multifunctionalization PAN-M Fiber with Chitosan via Covalent Bonds 247 11.4.1.3 Multifunction of PAN Fiber with MCT-β-CD 248

xii  Contents 11.5 Polyethylene Terephthalate: Functionalization Ways 249 11.5.1 Functionalization of PET with Basic Reagents 250 11.5.1.1 Dyeing of PET Functionalized with Agents Having Basic Character 253 11.5.2 PET Functionalization with Alcohols 255 11.5.2.1 Multifunctionalized PET Dyeing with Alcohols 257 11.5.3 PET-Multifunctionalization with MCT-β-CD 260 11.5.4 Functionalization of the PET Surface with Plasma Treatment 261 11.5.4.1 Dyeing of PET Functionalized by Means of Plasma and Grafting with Polyfunctional Compounds 264 11.6 Cotton: Multifunctionalization Ways 266 11.6.1 Surface Activation with Plasma Followed by Grafting with Polyfunctional Compounds 267 11.6.1.1 Dyeing of Multifunctionalized Cotton by Plasma and Grafting Treatments 269 11.6.2 Alkyl Chitosan Grafting on Cotton 269 11.6.2.1 Dyeing of Cotton Grafted with Alkyl Chitosans 273 11.6.3 Multifunctionalization of Cotton with Polyfunctional Compounds and Unconventional Dyeing 275 11.6.3.1 Functionalization of Cotton with Tetronic 701 and Chitosan 275 11.6.3.2 Functionalization of Cotton with a Tetrol (Tetronic 701) and MCT-β-CD 277 11.6.3.3 Successive Functionalization of Cotton with a Tetrol (Tetronic 701), Chitosan, and MCT-β-CD 277 11.6.4 Multifunctionalization of Cotton with Carbonyl Compounds and MCT-β-CD 278 11.7 Conclusions 279 References 280 12 Advanced Dyeing or Functional Finishing Kunal Singha, Subhankar Maity and Pintu Pandit 12.1 Introduction 12.2 Mechanism of Dyeing by Phase Separation 12.3 Advanced Dyeing and Finishing Techniques

291 292 293 293

Contents  xiii 12.3.1 12.3.2 12.3.3 12.3.4 12.3.5 12.3.6 12.3.7 12.3.8

Ultrasound Technology Ultraviolet (UV) Technology Ozone Technology Plasma Technology/Ion Implantation Technology Gamma Radiation Technology Laser Technology Microwave Technology E-Beam Radiation Technology/ Mass-Analyzed Ion Implantation 12.3.9 Supercritical Carbon Dioxide (Sc. CO2) Technology 12.4 Applications of Ultrasonics in Textiles 12.4.1 Principle of Ultrasound Dyeing Technique 12.4.2 Basic Design of the Ultrasound Dyeing Instrument Developed by SASMIRA, India 12.4.3 Different Section of the Machine 12.4.4 K/S Value 12.4.5 Dye Uptake 12.4.6 Comparison of Ultrasound Dyeing Technique with the Conventional Dyeing Technique for Various Textile Materials 12.4.7 Dyeing of Polyester by Disperse Dye 12.5 Conclusions References 13 Plasma and Other Irradiation Technologies Application in Textile Kartick K. Samanta, S. Basak and Pintu Pandit 13.1 Introduction 13.2 Plasma Treatment of Textile 13.3 Optical Properties of Plasma 13.4 Improvement in Hydrophobic Attribute 13.4.1 Surface Chemistry of Hydrophobic Textile 13.5 Improvement in Liquid Absorbency and Coloration 13.6 Plasma Treatment of Protein Fiber 13.6.1 On Silk Fiber 13.6.2 On Wool Fabric 13.7 UV Irradiation 13.8 Laser Irradiation 13.9 Electron Beam Irradiation 13.10 Summary References

293 294 294 295 295 296 296 296 296 297 298 299 299 300 301 301 303 304 305 309 310 312 314 316 317 320 322 322 324 325 326 327 327 328

xiv  Contents 14 Bio-Mordants in Conjunction With Sustainable Radiation Tools for Modification of Dyeing of Natural Fibers Shahid Adeel, Shumaila Kiran, Tanvir Ahmad, Noman Habib, Kinza Tariq and Muhammad Hussaan 14.1 Natural Dyes 14.2 Health and Environmental Aspects 14.3 Isolation Process 14.3.1 Conventional Methods 14.3.2 Modern Methods 14.4 Role of US and MW in Isolation 14.5 Fabric Chemistry 14.6 Shade Development Process 14.6.1 Chemical Mordant 14.6.2 Bio-Mordant 14.7 Arjun 14.8 Neem 14.9 Coconut 14.10 Harmal 14.11 Recent Advances Acknowledgments References

335 336 336 336 337 337 337 338 338 339 339 340 340 340 340 341 344 344

Index 349

Preface Humans have been using textiles since prehistoric times. Although initially used only to protect the body from environmental changes, those with high scientific knowledge and awareness are now focusing on multidimensional applications of textiles. To meet the needs of modern mankind, various modifications have already been implemented on textiles, ranging from simple coloration to advanced energy applications, and researchers are continuously exploring new frontiers in this field. Advancing conventional techniques with green and sustainable products that replace the harmful compounds in textile processing and the quest for advanced materials for functionalization of textiles are currently very much underway. All these developments have motivated us to compile this reference book with the help of eminent authors from around the world with expertise in textiles-related research areas. The 14 chapters of Frontiers of Textile Materials: Polymers, Nanomaterials, Enzymes, and Advanced Modification Techniques cover various research areas dealing with modification of textile materials. Following an introductory chapter on materials (polymers, nanomaterials, enzymes, etc.) for textile modification, the initial chapters are devoted to the construction and functional finishing of textile materials using polymers. The first few chapters explore nanomaterials for the textile industry, fabrication and characterization of nanomaterials, application on textiles and functionalities achieved on them. Two of the chapters focus on flexible electronics dealing with the incorporation of nanogenerators and solar cells into the matrix of textiles to design wearables. Further chapters discuss advanced dyeing and dyeing materials (biomordants, plasma and radiations) for sustainable and eco-friendly coloration. This book contains informative chapters from authors specializing in fields encompassing materials, dyeing, functional finishing and flexible electronics. Thus, the editors hope that students, researchers and academicians of various fields, such as textiles chemistry and dyeing, chemical engineering, environmental science, and materials science, will find this xv

xvi  Preface book to be of great interest and useful in their curriculum. We expect this book will definitely be helpful in inspiring new ideas in textiles research, leading to interdisciplinary research collaborations. At this time, we would like to thank those who have been supportive of this book in any way. We acknowledge the great efforts of the eminent authors without whom this book would have been unimaginable. We also appreciate the support of the publisher in showing interest in the compilation of such a reference book. Mohd Shabbir Shakeel Ahmed Javed N Sheikh January 2020

1 Introduction to Textiles and Finishing Materials Mohd Shabbir1* and Javed N. Sheikh2† Department of Chemistry, NIET, Greater Noida, UP, India Department of Textile Technology, Indian Institute of Technology, New Delhi, India 1

2

Abstract

Textile is one of the basic needs of the human being, and the modern human being has a lot of choices for their clothing. Textiles have various characteristics depending on the fibers they are made from, such as wool, silk, cotton, viscose, nylon, polyester, etc. and the finishing applied on them via materials such as finishing chemicals, nanoparticles, polymers, enzymes, etc. Thus, so many materials are available which can be utilized in the development of functional and smart textiles. In the era of technology (miniaturization of this world), flexible electronics based on textiles are gaining momentum. The chapter presents the emerging materials in the field of textiles with a major focus on the functionalization of textiles. In the next chapters of this book, all these are reviewed in great detail. Keywords:  Textiles, viscose, polyester, polymers, nanomaterials

1.1 Introduction The textile industry is of great importance to the economies of every country in terms of trade, employment, investment, and revenue. Simultaneously, the chemical processes associated with textile production generate a lot of waste, greenhouse gases, and consume a large amount of water [1]. Innovative research and developments are very much needed *Corresponding author: [email protected] † Corresponding author: [email protected] Mohd Shabbir, Shakeel Ahmed, and Javed N. Sheikh (eds.) Frontiers of Textile Materials: Polymers, Nanomaterials, Enzymes, and Advanced Modification Techniques, (1–12) © 2020 Scrivener Publishing LLC

1

2  Frontiers of Textile Materials for the textile industry to minimize waste production and maximize clothing production simultaneously. A series of steps are involved from textiles manufacturing to finishing and dyeing, need the attention of textile chemists as well as environmentalists. Technological advancements for functional finishing have emerged in recent years. Textile materials from the natural origin such as cotton, wool, and silk are prone to microbes, so antimicrobial finishing technologies are developed via application of polymers, nanomaterials, and dyes [2, 3]. This chapter overviews the advanced structural and finishing materials for textiles. All textiles fibers are polymers e.g. silk and wool are proteins made up of polymeric chains of amino acids, cotton is made up of glucose monomeric units and synthetic fibers Nylon and polyesters are the synthetic polymers. Chitosan, sericin, and tannins are a few examples of natural polymers used for functional finishing of textiles. Nanomaterials are considered as both present and future of every technological advancement including textiles. Various conventional methods of finishing have been replaced with new and technologically advanced techniques. In the next chapters of this book, all these aspects of the textiles industry are reviewed in great detail.

1.2 Polymers Textiles and polymers are the interconnected materials and all textiles fibers are polymers. Apart from this, polymers play an important role in textile processing and are utilized for various applications like sizing agents, thickeners for textile printing, finishing chemicals, coating chemicals, etc. As far as applications of polymers in finishing are concerned, they are widely utilized in various finishing treatments ranging from softening finish, stiffening finish, repellent finishes, antimicrobial finishes, flame retardant finishes, and abrasion-resistant finish. The conventional silicones are widely consumed polymers in textile finishing. Silicone softeners show various advantages over other types of softeners and the proper chemistry of silicones can be selected to fine-tune the properties of finished textile materials. Fluorochemicals supported on acrylic backbones are used for imparting water repellent finishing to textile materials. Starch, polyvinyl alcohol, polyvinyl acetates are used for imparting stiffness. With the development of technical textiles, the demand for functional textiles is increased which resulted in the development of functional finishes for textiles. The properties of polymers were tailor-made by selecting the suitable monomers and such polymers were utilized in the functional finishing of textiles. Textile coating and lamination have opened a new area

Textiles and Finishing Materials  3 of modification of textiles which has further enhanced the scope of polymers in textile finishing. The polymers like polyvinylchloride (PVC), polyvinylidene chloride (PVDC), acrylic polymers, silicones, fluoro-­polymers, rubbers (both natural and synthetic) find applications in the functional coating of textiles. The resultant film of a coated polymer can also be suitably modified using the various layers of a coating or by addition of fillers. The coating has an added advantage of higher add-on of functional chemical on fabric which can show enhanced functionalities as compared to low add-on involved in the conventional padding-based finishing process. The increase in awareness regarding health and hygiene and the requirement of protection against pathogenic microbes resulted in development of various polymers, which can act as antimicrobial finishes for textiles. Such polymers include natural polymers like chitosan, sericin and tannins, synthetic polymers like quaternized polymers, polymers with N-halamine moieties, biguanide-based polymers, and conjugated polymers such as polypyrrole and polyaniline. Chitosan is an interesting functional biopolymer, which is widely researched for its applications in textile finishing. The various reports regarding application of chitosan and its derivatives in antimicrobial finishing, flame retar­dant finishing, and multifunctional finishing are available in the literature. Smart textile and apparels are developed in recent times and led to the development of stimuli-sensitive polymers (SSPs), which show a reversible transformation from one state to another as a response to various stimuli from the environment [4]. The stimulus includes temperature, electric field, pH, light, pressure, sound, etc. Shape memory polymer is another important class of polymers, which can be integrated into textile substrates to obtain thermal and moisture control, self-adaptability of shape, shape retention, and smart wettability [5]. Even though smart polymers are available for textile applications, their integration/application in/on textiles is a big challenge. A continuous research in this area is expected to solve the technical issues in the application of such smart materials on textiles.

1.3 Nanomaterials Nanomaterials are defined as the materials of size in the range 1–100 nm. Nanomaterials are expected to have a higher efficiency than bulk materials owing to their larger surface area–mass ratio. Size and shape are the primary characteristics of nanomaterials responsible for the efficacies of the functional properties imparted by them. Designing of nanomaterials is widely studied under nanotechnology. The way of synthesis or fabrication

4  Frontiers of Textile Materials methods and the reducing or stabilizing agents determine the shape and size of nanomaterials which lead to their specific characteristics [6]. Today nanotechnology plays an important role in almost every aspect of life, having a wide range of applications such as biomedical, environmental, and textiles. The demand for high-quality textiles is highly increased nowadays with the rising population and developed clothing sense of human being, and the textile industry is highly pressurized to manufacture the best quality textiles [7]. Nanoscience and nanotechnology play an important role not only for textile functionalization but also for the remediation of textile effluent to keep water ecosystem clean. Both metal (Ag, Au, Cu, etc.) and metal oxide (ZnO, TiO2, etc.) nanomaterials had been explored toward textile functionalization in recent past. Some of these nanoparticles like silver, gold, zinc oxide, and titanium dioxide are widely studied for imparting antimicrobial, self-­cleaning, hydrophobic, and UV protection abilities to textiles [8–10]. Various fabrication and application processes on textile materials have been developed to get optimum benefits from nanoparticles. Eco-friendly fabrication of nanoparticles was also reported via in situ synthesis and simultaneous application on textiles using various plant extracts as reducing and stabilizing agents. Fabrication methods, characterization of nanomaterials, and application on textiles are discussed in detail in the coming chapters of this book.

1.4 Enzymes Textile chemical processing is water-intensive and generates large quantities of effluent, which necessitates the shifting to more eco-friendly enzymatic processes. Some of the enzymes are commercially exploited, which offers numerous advantages in textile chemical processes. Although some technical issues were witnessed for complete shifting to enzyme-based processes, the ongoing collaborative research in the field of biotechnology and textile processing might answer such issues. The ideologies of Green Chemistry [11] are truly followed by enzyme technology which being sustainable and hence can be a prudent choice. In the quest of the development of eco-friendly chemicals and processes for chemical processing of textiles, the increased interest has been shown by the research community in the exploration of new products through industrial biotechnology [12–15]. This resulted in the replacement of harsh chemicals and the development of some new alternatives providing a reduction in manufacturing cost and ecological problems. Enzymes are widely utilized in textile chemical processing including pre-treatments for

Textiles and Finishing Materials  5 removal of impurities, denim finishing like bio-washing, and also in the treatment of the effluents arising from textile industries. The rate of enzymatic reactions is dependent on various factors including pH, temperature, concentrations of enzyme and substrate, and presence of any activators or inhibitors/retarder [16]. Enzymes are ideal for chemical reactions because of their specificity for the substrate as per the reaction [17]. Some of the dominant processes where enzymatic technology is already established are pre-treatments of denim, bio-washing of denim, desizing, scouring and bio-polishing of cotton. Denim is a popular textile substrate among the people of all age groups. The denim garments with faded–abraded look are widely demanded, which were traditionally produced using washing with pumice stones which can cause deterioration of treated garment along with the machine damages [18, 19]. Such issues can be solved by the use of a variety of cellulases, working at broad temperature ranges and pH, which can be used alone or in combination with other enzymes [20–22]. Two critical issues are associated with bio-washing of denim like degradation of cotton fiber in case of uncontrolled treatment and indigo back-­staining/ re-deposition on the uncolored back side of denim [23]. These issues can be solved by controlling the bio-washing to the surface and the selection of proper cellulase. The efficient after-wash using soap, soda, peroxide, and optical brightening agent is generally done to remove the back-staining [24]. Bio-polishing is another important finishing process, which reduces hairiness by removing the protruding micro hairs of cotton and pilling of cellulose fabric leading to velvety, slicker feel, and brighter color [25]. This can also be achieved by using cellulase, which can hydrolyze cellulosic micro-fibrils [22, 26–29]. Agitation is an important factor, which facilitates the cellulolytic attack, which necessitates the use of textile machineries capable of producing agitation, like jet dyeing machines [26, 27, 30, 31]. Both bio-washing and bio-polishing involve two important aspects, viz. removal of fibrils and their suspension in aqueous treatment media thus preventing redeposition on the fabric. The accurate control of parameters, suitable agitation, the use of suitable dispersing agents/anti-redeposition agents based on polyvinylpyrrolidone and acrylates are therefore necessary to prevent redeposition of fuzz on fabric and achieve efficient bio-polishing. Apart from the actual application of enzymes in finishing, several enzymes like amylase, pectinase, catalase, and glucose oxidase are used in preparatory processes. Even though these are not directly used in finishing, these are used to remove impurities from the fabric, which also affects the efficiency of further coloration and finishing processes. The functional finishing of textiles is an upcoming area where enzymes can be explored. Laccase-mediated grafting of polyphenols on textile fibers

6  Frontiers of Textile Materials for functionalization is reported widely in the literature. Immobilization of enzymes, use of advanced techniques like ultrasound, and combined textile processes using a mixture of enzymes are the latest developments in the area of enzymatic textile processing.

1.5 Plasma and Radiations for Textiles Plasma is considered to be the fourth state of matter and can be utilized for activation, cleaning, surface deposition and functionalization of textiles. Applications of radiations are widely researched for the performance enhancement of various processes used in textile processing. Natural dyeing of textiles goes through various steps from the extraction of dyes to the application on textile materials. The first step starts from extraction, which is of high importance in term of getting the higher quantity of dyeing compounds in the extracts which ultimately affects the color strength of dyed textiles. Dyers usually go for aqueous extraction, which needs higher time and energy. Researchers nowadays are focusing to find efficient and innovative techniques to obtain natural dye compounds, which could provide better yield, minimize extraction time and solvent consumption [32]. Microwave-assisted and ultrasound-assisted extraction techniques already have been utilized and proved to be highly efficient. Microwave energy is considered more efficient for heating as it provides uniform heating in a reaction mixture unlike the ordinary methods of heating. It enables the heating of all particles at the same time with its easy penetration property into the particles of the matter and thus the solution is regularly heated to quickly attain the high temperature [33]. Microwave-assisted extraction was carried on Eucalyptus robusta leaves to get an optimal yield of total phenolic compounds and results were in accordance to prove it as a good eco-friendly alternative to conventional extraction [34]. Response surface methodology (RSM) and artificial neural network (ANN) modelling were applied in association with microwave-assisted extraction of dyeing compounds from pomegranate rind and application of microwave irradiation method proved to be a rapid and improved technique for dye extraction with improved yield and significantly reduced extraction time [35]. Plasma and radiations further have been utilized for improving dye absorptivity, disinfestation and imparting other functionalities on textiles [36–39]. Drábková et al. [40] studied the influence of gamma radiations for disinfestation of paper and textiles (silk and cotton), but their results suggested some structural changes in cellulosic and proteinaceous materials due to the treatment. Fabrics of polyester and polyamide were treated with

Textiles and Finishing Materials  7 atmospheric pressure plasma to successfully improve the wettability of fabrics after plasma treatment, while dryability was not improved significantly [41]. Samanta et al. [42] improved water and oil absorbency of textile substrates by treating them with atmospheric pressure cold plasma. Several studies were discussed about non-thermal plasma treatment of textiles for various functional characteristics by Morent et al. [43].

1.6 Flexible Electronics Miniaturization of things is leading to the development of countless tiny devices in our daily life use. Textiles can be a matrix to install them on clothing to function for various application areas from fashion and functional clothing to healthcare and interior design. Conducting yarns and fibers are very much popular in today’s research for integrating electronic devices in textiles. Materials such as conjugated polymers (e.g., polypyrrole (PPy), polyaniline (PANI), and poly (3,4-ethylenedioxythiophene) (PEDOT)), carbon nanotubes, graphene, etc., have been explored for this purpose of making the smart textiles. A lot of research has been focused for the envisaged functionalities, such as sensing, data processing and storage, as well as energy harvesting, e.g., by using the piezoelectric, thermoelectric, triboelectric, or photovoltaic effect and a lot to be explored in future. Processing and development of conducting yarns and textiles are well discussed in a review paper by Lund et al. [44]. In one of the studies, cotton was turned into conducting textiles with high porosity and excellent toughness by coating metal oxide on the cotton and subsequent pyrolysis [45]. Various formulations and inks have also been developed to make conducting fibers. Islam et al. [46] reported a simple, low cost, and highly scalable fabrication method of functional Carbon Black ink from dry charcoal, and it was then coated on cotton by pad–dry–cure method to get durable electrically and thermally conductive cotton E-textiles. In another study, a dense and thin layer of polypyrrole (PPy) was deposited onto the fabric surface by an improved in situ polymerization method. Some woven and knitted fabrics were then transformed into conductive electrodes of high electrical conductivity without compromising their breathability, flexibility, and comfortability [47]. Ye et al. [48] reported a scalable dip-coating strategy to construct conductive silk fibers (CSFs). Natural silk fibers were coated by a tailor-made carbon nanotube (CNT) paint without destroying the internal structure of the fibers. The CSFs developed possess characteristics such as high mechanical performance, super-hydrophobicity, solvent resistance, and thermal sensitivity. Polyurethane-coated Ni–Ti alloy fiber-based pressure sensors were

8  Frontiers of Textile Materials fabricated for real-time sitting posture correction and tested for durability aspects in terms of washing and sit-down numbers [49].

References 1. Filho, W.L., Ellams, D., Han, S., Tyler, D., Boiten, V.J., Paco, A.D., Balogun, A., A review of the socio-economic advantages of textile recycling. J. Cleaner Prod., 218, 10–20, 2019. 2. Shahid, M., Shahid-ul-islam, Mohammad, F., Recent advancements in natural dye applications: A review. J. Cleaner Prod., 53, 53, 310–331, 2013. 3. Yusuf, M., Shabbir, M., Mohammad, F., Natural Colorants: Historical, Processing and Sustainable Prospects. Nat. Prod. Bioprospecting, 7, 1, 123– 145, 2017. 4. Jassal, M. and Agrawal, A.K., Speciality polymers for the finishing of technical textiles, in: Advances in the Dyeing and Finishing of Technical Textiles, M.L. Gulrajani (Ed.), Woodhead Publishing, 2013. 5. Thakur, S., Shape Memory Polymers for Smart Textile Applications, in: Textiles for Advanced Applications, Bipin Kumar and Suman Thakur (Eds.), IntechOpen, 2017. 6. Shabbir, M., Wazed Ali, S., Mohammad, F., Eco-Fabrication of Nanomaterials for Multifunctional Textiles, in: Handbook of Ecomaterials, L. Martínez, O. Kharissova, B. Kharisov (Eds.), Springer, Cham, 2018. 7. Shahid-ul-Islam, Shabbir, M., Mohammad, F., Insights into the Functional Finishing of Textile Materials Using Nanotechnology, in: Textiles and Clothing Sustainability. Textile Science and Clothing Technology, S. Muthu (Ed.), Springer, Singapore, 2017. 8. Montazer, M. and Pakdel, E., Functionality of nano titanium dioxide on textiles with future aspects: Focus on wool. J. Photochem. Photobiol. C Photochem. Rev., 12, 4, 293–303, 2011. 9. Radetic, M., Functionalization of textile materials with silver nanoparticles. J. Mater. Sci., 48, 1, 95–107, 2013. 10. Shabbir, M. and Mohammad, F., Multifunctional AgNPs@Wool: Colored, UV-protective and antioxidant functional textiles. Appl. Nanosci., 8, 3, 545– 555, 2018. 11. Anastas, P.T. and Warner, J.C., Green chemistry: Theory and practice, Oxford University Press, New York, 1998. 12. Cegarra, J., The state of the art in textile biotechnology. J. Soc. Dyers Color., 112, 326–329, 1996. 13. Heine, E. and Hoecker, H., Bioprocessing for smart textiles and clothing, in: Smart Fibers, Fabrics and Clothing, X. Tao (Ed.), pp. 254–277, Woodhead Publishing, Cambridge, England, 2001.

Textiles and Finishing Materials  9 14. Gübitz, G.M. and Cavaco-Paulo, A., Biotechnology in the textile industry— Perspectives for the new millennium. J. Biotechnol., 89, 89–90, 2001. 15. Chen, J., Wang, Q., Hua, Z., Du, G., Research and application of biotechnology in textile industries in China. Enzyme Microb. Technol., 40, 1651–1655, 2007. 16. Martinek, R., Practical Clinical Enzymology. J. Am. Med. Tech., 31, 162, 1969. 17. Holum, J., Elements of General and Biological Chemistry, second ed., vol. 377, Wiley, New York, 1968. 18. Pazarlioglu, N.K., Sariisik, M., Telefoncu, A., Treating denim fabrics with immobilized commercial Cellulases. Process Biochem., 40, 767–771, 2005. 19. Yu, Y., Yuan, J., Wang, Q., Fan, X., Ni, X., Wang, P., Cui, L., Cellulase immobilization onto the reversibly soluble methacrylate copolymer for denim washing. Carbohydr. Polym., 95, 2, 675–680, 2013. 20. Bhat, M.K., Cellulases and related enzymes in biotechnology. Biotechnol. Adv., 18, 355–383, 2000. 21. Sarkar, A.K. and Etters, J.N., Kinetics of the enzymatic hydrolysis of cellulose. AATCC Rev., 1, 3, 48–52, 2001. 22. Araujo, R., Casal, M., Cavaco-Paulo, A., Application of enzymes for textile fibers processing. Biocatal. Biotrans., 26, 332–349, 2008. 23. Sinitsyn, A.P., Gusakov, A.V., Grishutin, S.G., Sinitsyna, O.A., Ankudimova, N.V., Application of microassays for investigation of cellulase abrasive activity and backstaining. J. Biotechnol., 89, 233–238, 2001. 24. Sheikh, J. and Bramhecha, I., Enzymes for Green chemical processing of cotton, in: The Impact and Prospects of Green chemistry for textile technology, S. Islam and B.S. Butola (Eds.), pp. 235–160, Woodhead Publishing, Elsevier, 2019 . 25. Ibrahim, N.A., El-Badry, K., Eid, B.M., Hassan, T.M., A new approach for biofinishing of cellulose-containing fabrics using acid cellulases. Carbohydr. Polym., 83, 116–121, 2011. 26. Cavaco-Paulo, A. and Almeida, L., Kinetic parameters measured during cellulase processing of cotton. J. Textile Inst., 87, 227–233, 1996. 27. Cavaco-Paulo, A., Morgado, J., Almeida, L., Kilburn, D., Indigo backstaining during cellulase washing. Text. Res. J., 68, 398–401, 1998. 28. Lenting, H.B. and Warmoeskerken, M.M.C.G., Guidelines to come to minimized tensile strength loss upon cellulase application. J. Biotechnol., 89, 227– 232, 2001. 29. Stewart, M.A., Biopolishing cellulosic nonwovens, PhD Thesis, North Carolina State University, United States, 2005. 30. Cavaco-Paulo, A. and Almeida, L., Cellulase hydrolysis of cotton cellulose: The effects of mechanical action, enzyme concentration and dyed substrates. Biocatalysis, 10, 353–360, 1994. 31. Cortez, J.M., Ellis, J., Bishop, D.P., Cellulase finishing of woven, cotton fabrics in jet and winch machines. J. Biotechnol., 89, 239–245, 2001.

10  Frontiers of Textile Materials 32. Simić, V.M., Rajković, K.M., Stojičević, S.S., Veličković, D.T., Nikolić, N.Č., Lazić, M.L., Karabegović, I.T., Optimization of microwave-assisted extraction of total polyphenolic compounds from chokeberries by response surface methodology and artificial neural network. Sep. Purif. Technol., 160, 89–97, 2016. 33. Büyükakıncı, B.Y., Usage of microwave energy in Turkish textile production sector. Energy Procedia, 14, 424–431, 2012. 34. Bhuyan, D.J., Van Vuong, Q., Chalmers, A.C., van Altena, I.A., Bowyer, M.C., Scarlett, C.J., Microwave-assisted extraction of Eucalyptus robusta leaf for the optimal yield of total phenolic compounds. Ind. Crops Prod., 69, 290– 299, 2015. 35. Sinha, K., Saha, P.D., Datta, S., Response surface optimization and artificial neural network modeling of microwave assisted natural dye extraction from pomegranate rind. Ind. Crops Prod., 37, 1, 408–414, 2012. 36. Adeel, S., Gulzar, T., Azeem, M., Saeed, M., Hanif, I., Iqbal, N., Appraisal of marigold flower based lutein as natural colorant for textile dyeing under the influence of gamma radiations. Radiation Physics Chem., 130, 35–39, 2017. 37. Szulc, J., Urbaniak-Domagała, W., Machnowski, W., Wrzosek, H., Łącka, K., Gutarowska, B., Low temperature plasma for textiles disinfection. Int. Biodeterior. Biodegrad., 131, 97–106, 2018. 38. Zanini, S., Freti, S., Citterio, A., Riccardi, C., Characterization of hydro-and oleo-repellent pure cashmere and wool/nylon textiles obtained by atmospheric pressure plasma pre-treatment and coating with a fluorocarbon resin. Surf. Coat. Technol., 292, 155–160, 2016. 39. Zanini, S., Citterio, A., Leonardi, G., Riccardi, C., Characterization of atmospheric pressure plasma treated wool/cashmere textiles: Treatment in nitrogen. Appl. Surf. Sci., 427, 90–96, 2018. 40. Drábková, K., Ďurovič, M., Kučerová, I., Influence of gamma radiation on properties of paper and textile fibers during disinfection. Radiation Physics Chem., 152, 75–80, 2018. 41. Kan, C.W. and Yuen, C.W.M., Effect of atmospheric pressure plasma treatment on wettability and dryability of synthetic textile fibers. Surf. Coat. Technol., 228, S607–S610, 2013. 42. Samanta, K.K., Jassal, M., Agrawal, A.K., Improvement in water and oil absorbency of textile substrate by atmospheric pressure cold plasma treatment. Surf. Coat. Technol., 203, 10–11, 1336–1342, 2009. 43. Morent, R., De Geyter, N., Verschuren, J., De Clerck, K., Kiekens, P., Leys, C., Non-thermal plasma treatment of textiles. Surf. Coat. Technol., 202, 14, 3427–3449, 2008. 44. Lund, A., van der Velden, N.M., Persson, N.K., Hamedi, M.M., Müller, C., Electrically conducting fibers for e-textiles: An open playground for conjugated polymers and carbon nanomaterials. Mater. Sci. Eng.: R Rep., 126, 1–29, 2018.

Textiles and Finishing Materials  11 45. Lam, D.V., Won, S., Shim, H.C., Kim, J.H., Lee, S.M., Turning cotton into tough energy textile via metal oxide assisted carbonization, Carbon, 153, 257–264, 2019. 46. Islam, R., Khair, N., Ahmed, D.M., Shahariar, H., Fabrication of low cost and scalable carbon-based conductive ink for E-textile applications. Mater. Today Commun., 19, 32–38, 2019. 47. Lv, J., Zhou, P., Zhang, L., Zhong, Y., Sui, X., Wang, B., Chen, Z., Xu, H., Mao, Z., High-performance textile electrodes for wearable electronics obtained by an improved in situ polymerization method. Chem. Eng. J., 361, 897–907, 2019. 48. Ye, C., Ren, J., Wang, Y., Zhang, W., Qian, C., Han, J., Zhang, C., Jin, K., Buehler, M.J., Kaplan, D.L., Ling, S., Design and Fabrication of Silk Templated Electronic Yarns and Applications in Multifunctional Textiles. Matter, 1, 5, 1411–1425, 2019. 49. Kim, M., Kim, H., Park, J., Jee, K.K., Lim, J.A., Park, M.C., Real-time sitting posture correction system based on highly durable and washable electronic textile pressure sensors. Sens. Actuators, A, 269, 394–400, 2018.

2 Polymers for Textile Production Mohammad Tajul Islam1*, Md. Mostafizur Rahman2 and Nur-Us-Shafa Mazumder3 Department of Textile Engineering, Ahsanullah University of Science and Technology, Dhaka, Bangladesh 2 Department of Textile Engineering, World University of Bangladesh, Dhaka, Bangladesh 3 Department of Textile Engineering, Port City International University, Chittagong, Bangladesh

1

Abstract

For the obvious reason of human needs, the textile sector has become the second-­ largest manufacturing industries just after the agricultural sector. One of the important and major areas of applications of polymers is the textile sector, more specifically in fiber production. Polymers are essential chemicals for the production of textile. Polymers are used in every step of textile manufacturing from fiber manufacturing to textile coloration and finishing. This chapter will discuss the source, chemical structure and properties, manufacturing process, and characterization of natural polymers such as cellulose, keratin, and fibroin as well as synthetic polymers such as polyethylene, polypropylene, polystyrene, polyesters, polyamides, polyurethanes, polytetrafluoroethylene, polyvinyl chloride, and polyvinyl alcohol. This chapter will also give an insight into the basics of polymer, classification of polymer, and polymerization process. Keywords:  Polymers, textile production, natural polymer, synthetic polymer and fiber

2.1 Polymers Polymer came from the Greek word “poly” and “meros”, where poly means many and meros means part [1]. Polymers are macromolecules or giant *Corresponding author: [email protected] Mohd Shabbir, Shakeel Ahmed, and Javed N. Sheikh (eds.) Frontiers of Textile Materials: Polymers, Nanomaterials, Enzymes, and Advanced Modification Techniques, (13–60) © 2020 Scrivener Publishing LLC

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14  Frontiers of Textile Materials substances made from interlinking of many small units. These small units from which polymers are formed are known as a monomer, which means single part. The process by which individual monomers are linked together to form polymers is known as “polymerization” [2]. The polymer can be formed from one type of monomer. The polymer formed from one type of monomer is known as a homopolymer. For examples, polyethylene is formed only from ethylene monomer. On the other hand, the polymer formed from more than one type of monomers is called copolymer. Polyester can be taken as an example here, two types of monomers—acid and alcohol are used for the polyester polymerformation. Polymers vary from small molecular weight compounds in many ways. The molecular weight of a small molecule is fixed whereas the polymer’s molecular weight can vary. The molecular weight and size of a polymer depend on the number of monomers in a polymer. The number of monomers in a polymer is denoted by the degree of polymerization (DP). The molecular weight of a polymer is the product of the molecular weight of the repeat unit and the DP [3]. For example, polyethylene polymer with a DP of 1,000 and ethylene (–CH2–CH2–) as repeat unit (molecular weight of ethylene is 28), the molecular weight of the polymer will be 28 × 100 = 2,800. This very high molecular weight of the polymer makes its behavior different from commonly known lower molecular weight chemicals such as water. Solid water melts at 0°C, and on further heating boils at 100°C into gaseous form. On the other hand, polymer does not melt at any particular temperature. A solid polymer becomes softer on heating and on further heating turns into viscose molten mass. On further heating, it may decompose but usually does not convert into gaseous form. Another major difference between polymer and lower molecular weight compound lies in their solubility behavior. Lower molecular weight compound like sugar dissolves in the water up to a certain limit. More sugar than the saturation limit does not go into solution, they settle at the bottom as solid. The viscosity of the water and water containing sugar is not much different. On the other hand, polymer does not go into solution immediately. As polymers are added into water, they absorb water first then swelled and their shape changes and goes into solution after certain times. As more and more polymers are added the required time it takes to go into solution increases. Compare to lower molecular weight a very large amount of polymer can be added into the water without reaching saturation point. Here, the viscosity increase is prominent compared to sugar and water solution. The polymer in water never retains in its solid form like sugar in water [2].

Polymers for Textile Production  15

2.2 History of Polymer The history of natural polymers is a few billion years old! As the living body is made of protein, a natural polymer, it can be said that polymers were present in this world before human exist! Polymers had appeared in many natural forms like vegetable, animal, and mineral substances. The human had been using these polymers such as cellulose, starch even before the understanding of polymers. Rubber the natural polymer had been using science 15th century. During that time, it was used for playing a bouncing game, and they called it “weeping wood” as it could rub off pencil marks, which a few centuries later grew into a multibillion-dollar rubber industry. Until 1839 rubber could not be used successfully as it was sticky or become sticky during the summer heat. Charles Goodyear found that treating rubber with nitric acid made the rubber heat resistant and it did not adhere to itself. However, acidic treatment was sufficient only to prevent surface stickiness but internal rubber still remains susceptible to heat. Later he found that treating rubber with led and sulfur gave it far superior properties, which is known as vulcanization, the secret that made the rubber commercially successful. The synthesis of synthetic rubber from isoprene was first reported in 1875. The first commercially successful synthetic rubber was polychloroprene obtained formed chloroprene. Fiber is threadlike, flexible and finer substance. Fibers can be metallic, mineral, or organic materials. All non-metallic fibers are formed from polymeric materials. Until the beginning of the 20th-century textile fibers come from natural sources like plant: cotton, flax, jute, and animal: silk, wool. It is believed that flax fibers were used in 3800 BC in Egypt to weave fine linen cloth. References to hemp and ramie can be found in Chinese writing dated 2800 BC. Wool has been used for clothing for at least 5,000 years. Until the end of the 19th and the beginning of the 20th century, all fibers came from natural sources. During this period people discovered that man-made fiber can be produced. Early man-made fibers were known as regenerated fiber as these fibers were obtained from natural polymers like cellulose from wood. Soon after around 1930 humans were able to produce synthetic fibers. The first regenerated cellulose was based on nitrated cellulose by Swan. Cross and Bevan discovered that cellulose can be converted by alkali and carbon disulfide to form sodium cellulose xanthate, which then can be reconverted into cellulose by various reagents in 1894. This new regenerated fiber is known as “viscose,” which had few advantages over nitrated cellulose. The commercial viscose was developed in 1903. Nylon 66 the first synthetic fiber was invented by Carothers. In 1929

16  Frontiers of Textile Materials he published this polycondensation theory and compared it with polyaddition. Nylon 66 was commercialized before 1940 and continues to grow its importance today. Carothers was also investigating several polyesters under DuPont program started in 1929. These polyesters were mainly aliphatic and were not much useful due to its low melting temperature. In 1941, Whinfield and Dickson produced aromatic polyester known as PET polyester. The properties of this polyester found very suitable to be used as fibers [4].

2.3 Classification of Polymers There are many polymers with a variety of different behaviors. They can be classified in different ways based on their origin, physical properties, thermal behavior. 1. B  ased on Sources: Source of origin is the easiest way to classify a polymer. Based on their origin polymers are classified into natural and synthetic. i. Natural Polymer: Polymers have been found naturally existing in natural sources like vegetable and animals are known as natural polymers. Some examples include cellulose and starch present in vegetables, the protein present in animals and rubber from plant’s latex. ii. Synthetic Polymer: Polymers that are produced artificially in labs from lower molecular weight compound are known as synthetic polymers. They are produced commercially by the industries according to the demand. Commonly produced synthetic polymers that we used in our day-to-day life are Polyethylene, PVC, Polyester, Nylon, etc. iii.  Semi-synthetic Polymer: Polymers obtained by the modification of natural polymers. These types of polymers also are commercially important like vulcanized rubber, where the rubber is treated with sulfur for cross-linking between the polymers. C ellulose acetate is another example of a semi-synthetic polymer. Naturally occurring cellulose polymers are acetylated to produce a cellulose derivative known as cellulose acetate.

Polymers for Textile Production  17 2. B  ased on Polymer Structure: Based on the structure polymers are classified as follows: i. Linear Polymer: These polymers are straight and longchain polymer. These are the high-density polymer as polymers are straight a compact structure is possible to obtain. Polymers’ melting temperature is generally very high due to high density. PVC is a straight-chain polymer. ii.  Branch Chain Polymer: As the name suggests, polymers have a branch chain at random point of the main chain. Branching does not allow polymers to be packed closely; as a result, low-density polymer with lower melting temperature is obtained. iii.  Cross-linked Polymer: Polymers are internally linked with each other are known as cross-linked polymers. Monomers with tri-functional groups are prone to form a cross-linked network. Cross-linked polymers are rigid and brittle. Urea and Melamine formaldehyde are examples of cross-linked polymers. 3. Based on Type of Polymerization: The process by which monomers are linked together to form a polymer is called polymerization. Based on polymerization types polymers are classified as follows: i.  Addition Polymers: Polymers that are produced by addition polymerization process is called addition polymers. Monomers linked together without any elimination in this process. In this case, double or triple bonds present in the chemical structure of the monomers work as a functional group. Monomer and polymer have the same composition as no elimination of chemical species of monomer take place. Polyethylene, PVC, etc., are addition polymers. ii. Condensation Polymers: Polymers produced by the combination of monomers with the elimination of small molecules like water, methanol etc. Active reactive sites present in the monomer work as functional groups here. Polyester, Nylon is the examples of condensation polymers. 4. Based on Thermal Behavior: Polymers behave differently when the heat is applied. Based on the behavior of heating polymers are classified as follow:

18  Frontiers of Textile Materials

i.  Thermoplastic: Polymers without cross-linking soften on heating and can be given any shape. These polymers on cooling become hard again and retain its shape. Polymers those soften on heating and stiffen on cooling are known as thermoplastic polymers. This process can be repeated several times without any deterioration of the properties of the polymers. PVC, Nylon, Polyester are common examples of thermoplastic polymer. ii.  Thermosetting: Polymers those generally undergo chemical changes during heating known as thermosetting polymers. These are generally low molecular weight semi-liquid substance, on heating, they start crosslinking with each other and become hard, insoluble and infusible masses. They form three-dimensional linking on heating which is irreversible. Urea, melamine– formaldehyde, and Bakelite are the common examples. 5. Based on Ultimate Form and Use: Intramolecular forces are the forces that hold the atom in a polymer chain whereas intermolecular forces are the forces between the molecules. The form of a polymer ultimately depends on these two forces. Based on the form and uses polymers are classified as follows [5]: i. Plastics: These polymers are long-chain polymers where intermolecular forces hold them together. They do not have any cross bonds and can be shaped into hard and tough when pressure and heat is applied. Polystyrene and PVC are examples of polymers used as plastic. ii. Elastomers: Polymers that are elastics in nature and rubber-like solid material are known as elastomers. Polymers are cross-linked with each other so that they can recover to original shape after releasing from stress. Polymers that easily stretched and come back to their original shape after releasing stress are called elastomers. Vulcanized rubber and synthetic rubber are examples of elastomers. iii.  Fibers: Polymers have strong intermolecular forces results in high strength and less elasticity can be used as fiber. Fibers are a finer, flexible, and thread-like substance that can be woven easily. Fiber has a high melting temperature with a sharp value. Nylon66 and Polyester are common examples of fiber [2].

Polymers for Textile Production  19

2.4 Polymerization A polymer is formed by the inter-linking of monomers. The process where the polymer is formed by the interlinking of many monomers is called polymerization. Basically, two types of reactions are involved in polymerization. Monomers are either linked together without any elimination, this type of reaction is called addition reaction or chain polymerization. Or reaction between the reactive groups of the monomers where elimination of low molecular compound is involved, this type of reaction is called condensation reaction or step polymerization [6].

2.4.1 Chain Polymerization Monomers with double or triple bonds can react without any elimination. This type of polymerization involves joining of the monomers very rapidly. As no byproduct is formed in this type of polymerization the polymer and the monomer have the same elemental composition. The functionality of the monomers is provided by the double or triple bonds present in the monomer. Three major steps involved in chain polymerization: initiation, propagation, and termination. The chain polymerization process can be brought by free radical, ionic or coordination techniques. Depending on techniques involved in the polymerization, chain polymerization can be classified as Free-radical, Ionic, and Coordination polymerization. 1. F  ree-Radical Polymerization: The initiation of chain growth is caused by a free-radical, which is the decomposition product of initiators. The process (Figure 2.1) involves continuous and very rapid addition of the monomers to form polymer chains. Initiators are thermally unstable compounds and decomposed into free radicals when energy is supplied in terms of heat, light, or catalyst. A free radical is highly reactive and attacks the double bond of the monomers. This attack results in the attachment of the initiator to the monomer and simultaneously transfers the radical side to the monomer. This step is known as initiation. The monomer bearing the radical is reactive now and attacks the second monomer. As a result, the second monomer is attached to the first and radical site is transferred to the second. This reaction goes on; monomers keep successively adding to the chain and free radical remains on the

20  Frontiers of Textile Materials R

+

H 2C

R

CH

CH2

X

X

R

CH2

CH

CH + n H2C

CH

X

X

R

CH2

CH X

CH2

n

Figure 2.1  Free radical polymerization.

last monomer. This step is called propagation. As more and more monomers are added to the chain the length of the polymer increases. Lastly, the step where the growth of the polymer chain is arrested known as termination step. There are several ways for the termination of the free radicals like coupling, disproportion, chain transfer and presence of inhibitor [2]. 2.  Ionic Polymerization: The ionic polymerization also involves attaching like chain polymerization. But this time monomer is attacked not by an unpaired electron but by either positive or negative ion. If the initiation and propagation are done by a positively charged ion is called cationic polymerization and if by a negative ion it is called anionic polymerization. Like free radical polymerization, cationic polymerization also has three steps: initiation, propagation, and termination. Anionic polymerization also has two steps: initiation and propagation. But the termination of the anionic polymerization is not a simultaneous process unless strong cationic agents are present in the reactor. Polymers produced by anionic polymerization are live polymers as they are active and can react anytime if a favorable condition is given. Figure 2.2 shows an example of an ionic polymerization. 3. Coordination Polymerization: Chain polymerization started by a coordination bond and goes on through this coordination bond is known as coordination polymerization (Figure 2.3). Olefins monomers form a complex with organometallic compounds in the first step. A coordination bond is involved

CH X

Polymers for Textile Production  21 H+ + H2C

H

CH

CH2

X

X

H

CH2

CH+

CH+ + n H2C

CH

X

X

H

CH2

CH2 CH+

CH X

X

n

Figure 2.2  Ionic polymerization.

CH2

R

CH2

CH2

HC CH2

+

HC CH2

Mt–

R

HC

CH2 Mt 2–

CH2

Figure 2.3  Coordination polymerization.

between the metal and the carbon of the monomer in this complex. Afterward, more monomers keep successively adding to the polymer chain through this coordination bond. As the monomers are inserted between the metal and the carbon of the monomer this polymerization is also known as insertion polymerization.

2.4.2 Step Polymerization Monomers having reactive groups can react with themselves through a stepwise slow reaction to form a polymer. As this type of reaction, goes stepwise manner it is thereby slow, unlike chain polymerization. This type of reaction mostly accompanied by the elimination of small compound through step polymerization may proceed without any elimination. Composition of the monomer and repeat unit will be the same or not depending on the elimination. If no elimination is involved in the polymerization the composition of the monomer and the repeat unit will be the same. If byproduct is formed then the composition of the

22  Frontiers of Textile Materials monomer and the repeat unit will not be the same. Poly condensation, polyaddition, and ring-opening are the most common examples of step polymerization [3]. 1. P  olycondensation: Monomers containing reactive groups can be condensed by reacting with each other. Elimination of small molecules is known as condensation. As condensation is involved in every reaction during polymerization this polymerization is called polycondensation (Figure 2.4). Monomers must have two functional groups for the polycondensation to proceed. Only one type of reaction is involved in polymer formation. The polymer formed still have the two reactive groups at their chain end hence polymers are active. 2. Polyaddition: This type of polymerization is brought about by the migration of atom from one monomer to another. Monomers having double bonds or reactive groups as functional groups can undergo this type of reaction. Styrene can be polymerized by this method (Figure 2.5). Hydrogen atom transfer from one monomer to another and simultaneously monomers keep adding with one another. Like chain polymerization monomers are added without producing any byproduct. An interesting feature is that chain HOOC

R1

COOH + HO

R2

OH

HO

CO

R1

COO

R2

O

H n

CH

CH

Figure 2.4  Polycondensation polymerization. H2C

CH

H2C

CH

H2C

C

CH

CH

+

H2C C

CH

CH

H2C +

CH

H2C C

CH2 CH

n n

Figure 2.5  Polyaddition polymerization.

Polymers for Textile Production  23 H2C

NH

5

HOOC

CH2

5

NH2

H2O CO

HOOC

CH2

5

NH2 + n HOOC

CH2

5

NH2

HO

CO

CH2

NH

H n+1

Figure 2.6  Ring-opening polymerization.

polymerization requires either free radicals or ions for polymerization to proceed, whereas styrene can be polymerized without any of them. But like in chain polymerization monomers here do not react rapidly. As every reaction requires the transfer of an atom this type of reaction requires time. Monomers having reactive functional groups can also undergo polyaddition polymerization without any byproduct. For example, polyurethane polymer is formed by the reaction between diisocyanates and diols where a transfer of atom is involved. Hydrogen from diol transfer to diisocyanates results from the addition of the two monomers [7]. 3. Ring-opening: Monomers having a ring structure can be polymerized after the opening of the ring. Monomers after opening follow either polyaddition or polycondensation type of polymerization. Ethylene oxide and caprolactam are the examples of the monomers those polymerized by ring-opening polymerization. Where ethylene oxide follows polyaddition reaction and caprolactam follows polycondensation polymerization after their ring is opened [1]. Figure 2.6 is an example of a ring-opening polymerization.

2.5 Polymers in Textile Fibers Fiber is defined as thread-like form substance without any restriction on its chemical composition. Fibers are available in different forms such as metallic, mineral, or organic. All non-metallic fibers are polymeric

24  Frontiers of Textile Materials materials available in nature or synthesized by man. Fibers found in nature have been used for long such as cotton, wool, silk. Organic synthetic fibers are mostly thermoplastic, although thermosets are also possible. Here polymers that constitute textile fibers are described.

2.5.1 Natural Polymers 2.5.1.1 Cellulose Cellulose is a linear polymer of 1,4 β glucan, is the most copious polymer available worldwide. Cellulose, the basis of all plants fibers has a formula of (C6H10O5)n (Figure 2.7). The molecular weight of cellulose varies widely depending on its sources. The DP of cellulose is probably between 2,000 and 3,000. Some estimates put this figure even higher; cotton cellulose may contain as many as 10,000 glucose units per molecule. Cellulose is produced by natures, partially in pure form like seed hairs in cotton plant, but mostly combined with lignin and another polysaccharide, called hemicellulose [8, 9]. Hemicellulose is the second available abundant polymer available in nature after the cellulose. Roughly one-fourth materials of a plant are hemicellulose. Hemicelluloses are branched-chain non-crystalline low molecular weight polymer with a degree of polymerization of 80–100. Their general formulas are (C5H8O4)n and (C6H10O5)n [10]. Cellulose is the basic structural component of the plant cell wall, 33 percentages of all vegetable matters are comprised of cellulose (90% of cotton and 50% of wood is cellulose). Maximum quantities of cellulose are available to us in the plant world. We use a very negligible amount of cellulose for making fine fibers such as cotton. Most of it is used as structural materials of tree such as stems and leaves. This cellulose is largely useless to us for using directly as fiber; it is in fibrous form, but contaminated with other substances.

CH2OH H

H

O H OH

OH H

OH H

OH

H

H

CH2OH

HO

O

H

H

H O

CH2OH

OH H

O H

H

H

OH

H H

H O CH2OH

n

Figure 2.7  Structure of cellulose polymer.

HO

O

H OH

H

H

O

OH

Polymers for Textile Production  25 In the last century, human has learned to convert this natural cellulose into a suitable state for using as textile fibers. These types of fibers are known as regenerated fibers. The cellulosic fibers we are using now can be classified by referring to the part of a plant from which it comes. There are three major types: 1. Seed and Fruit fibers, i.e., Cotton, Coir, Kapok, etc. 2. Bast fibers, i.e., Jute, Hemp, Kenaf, etc. 3. Leaf fibers, i.e., Sisal, Henequen, etc.

2.5.1.2 Cotton Cotton is the most important textile fiber, as well as cellulosic textile fiber in the world, used to produce apparel, home textiles, and industrial products. 40% of fiber consumed worldwide in 2004 was cotton [11]. Cotton is seed fiber from the plant of the order Malvales, family Malvaceae. Raw cotton, after ginning and mechanical cleaning is approximately 95% cellulose [12]. Properties Physical Properties Cotton is a moderately strong fiber; tenacity is 3.0–5.0 g/den. The elongation property of cotton is not good; fiber does not stretch easily. It has only 5–10% elongation at break. The fiber has excellent resistance to heat. It does not degrade readily; turns yellow after several hours at 120 °C and decomposed at 150 °C. Chemical Properties Cotton is attacked by hot dilute or cold concentrated acids. But, it has resistance to cold concentrated acid. Cotton has excellent resistance to alkalis. It swells in caustic alkali, and no damage takes place with careful treatment with alkali. Uses Cotton is used widely as a fabric for hot weather wear; however, it is also able to provide warmth as well. Cotton fibers are able to absorb ample amount of moisture, garments made of cotton are therefore comfortable and cool. This absorbency makes it particularly useful for household fabrics like sheets and towels. It is widely used for making raincoats. The versatility of cotton has made it into the most widely used of all textile fibers. It goes onto carpets and curtains, shoes, clothing, and hats [10].

26  Frontiers of Textile Materials

2.5.1.3 Jute Like the other bast fibers, jute has been using from the prehistoric times. Jute is a bast fiber composed of 60–70% cellulose, 12–13% hemicellulose, and 12–15% lignin. This fiber is mainly grown in Bangladesh, India, Myanmar, China, Nepal, and Thailand. Among the thirty Corchorus species, but only two of them Corchorus capsularis and Corchorus olitorius are widely known [13]. Jute is a cheap fiber and along with its strength and availability in large quantity has carried it into making packing clothes and sacks. This fiber is also used for storage and transporting agricultural products. The resistance to elongation has made it particularly useful for the above uses. Curtain and furnishing fabrics are also can be made from finer qualities of jute. Nowadays jute is successfully blended with cotton fiber for making denim fabric [12].

2.5.1.4 Keratin Keratin is a structural name of proteins, which are available in the outer layer of human skin, in hair, and nails. Keratin has the ability to selfassemble into a bundle of fiber. Within the fiber bundle, individual polymer chains are cross-linked with S-S linkage involving the cysteine side chain. As a result, keratins are tough insoluble products [14]. Humans have used and developed keratin from animals over many thousands of years, e.g., animal skins for protection, different kind of horns, etc. [15]. The side groups of the keratin chain (Figure 2.8) may vary to a large extent in size and chemical nature. Some of the side chains may be hydrophilic and some of them may be hydrophobic, and acidic or basic.

CH2

H2N

NH

CO

CO

NH

CH CH2

CH2

NH

CO

4

NH2

CO

CH CH2

CH2

NH

NH

CO

CO

CH H2C

NH

NH

CO

CH3

CH H2C

2

COOH

SH

HO

Figure 2.8  Structure of keratin.

CH2

Polymers for Textile Production  27 Hydrocarbon present in the keratin chain as a side chain is non-polar and hence hydrophobic in nature. On the other hand, the hydroxyl-containing side chain gives hydrophilic characteristics to the chain. The side chain constitutes about 50% of the weight of the polymer. Cystine results in a considerable amount of cross-linking in the fiber and plays an important role in determining many properties of the polymer [16].

2.5.1.5 Wool The wool fiber is mainly composed of a protein called keratin. The structure of keratin is shown in Figure 2.2. The basic composition of keratin in different types of wool is almost the same, but only the sulfur content differs. This component is responsible for the various characteristics of wool fiber. Wool fiber lost its market during the Second World War because of the invention of many synthetic fibers. The consistent properties and stable price of synthetic fibers are the main reasons for declining the market share of wool fiber. As yet no synthetic fibers possess all the natural properties of wool fiber [17]. Properties Physical Properties The tensile strength of wool is in the range of 1,190–230 kg/cm2. The tenacity of wool fiber is of 1.0–1.7 g/den in the dry state, and 0.8–1.6 g/ den in wet state, respectively. It can be elongated to 25–35% before the break. Wool is very resilient in nature due to its high elongation at break coupled with high elastic recovery. It can recover completely of about 2% extension. Chemical Properties Wool can absorb moisture to a greater extent than any other fibers. Its moisture regain is as high as 17%. Wool is weakened by acids. It can be decomposed completely into amino acid by hot concentrated sulfuric acid. It has general resistance to other mineral acids. Wool is very sensitive to alkali. Caustic soda can dissolve wool completely. It has good resistance to dry cleaning solvents. Uses Wool is best known for its warmth. It has been used as clothing for winter such as jacket, sweaters, cardigans, pullovers, inner garments. Wool fiber is also used as filler in the duvet. Blanket made of wool fiber is popular in winter countries.

28  Frontiers of Textile Materials H N

C

O HC

C

R N

CH

H C

N

O CH

R

H

O

R

R

O

H

R

CH

N

C

CH

N

C

CH

C

N

O

H

R

O

H

H

O

R

H

O

N

HC R

C

N H

CH

C O

N

CH

C

R

Figure 2.9  Structure of fibroin.

2.5.1.6 Fibroin Fibroin polymer is an insoluble protein composed of long-chain amino acids basically attached by peptide link with hydrogen bonding [18, 19]. The amino acid composition has been investigated and reported by many researchers. In general, fibroin is composed of around 87% short-chain amino acid. Fibroin is a complicated compound of carbon, oxygen, and nitrogen. The chemical structure is given in Figure 2.9.

2.5.1.7 Silk Silk, the only natural filament, is composed of fibroin protein produced by arthropods [20]. A silk filament contains 72–81% fibroin, 19–28% sericin, 0.8–1.0% fat and wax, and 1.0–1.4% coloring matter and ash of the total weight. The silkworm has brins, which are nothing but two excretory canals or sericteries. Liquid fibroins are extruded by the silkworm from the brins, which unite in the spinneret on its head. Sericin is another protein secreted by the silkworm which cemented together liquid fibroins extruded from brins, as a result, a single continuous filament is produced. The filament is thus made by the union of two brins held together by sericin. Sericin acts as a glue to fix fibroin fiber together in cocoons [21].

Polymers for Textile Production  29 Properties Physical Properties Silk is a strong filament. The tenacity of silk filament is usually of 3.5–5.0 g/den. It loses strength when wet. Generally, it retains 70–85% of dry strength after wetting. It does not elongate much. Silk filament shows an elongation at break of 20–25% under normal condition. Elastic recovery is poor compared to wool. Silk can be permanently stretched if it is drawn about 2% to its original length. Chemical Properties Moisture regain of silk filament is high. It has a regain of 11%. Silk can be decomposed into its constituent amino acid by strong acids. However, if applied carefully with moderate concentration silk fabric shrinks giving an especial effect known as crêpe. Dilute acids under mild condition is not harmful to silk. Silk can be dissolved in a concentrated caustic solution. However, silk takes relatively more time to be damaged by alkali compared to wool. Uses Silk has been ruled as a queen of fibers for hundreds of years. Silk has been used as desirable apparel for a long time due to the combination of high strength, flexibility, good moisture absorption, softness, and luxurious appearance.

2.5.2 Synthetic Polymers 2.5.2.1 Polyethylene Polyethylene or polythene (abbreviated PE, chemical formula [C2H4]n) is the most commonly used thermoplastic polymer of polyolefin’s group. A polyolefin is a polymer of olefin monomer, olefin is also known as alkene with the general formula of CnH2n (Figure 2.10). Besides polyethylene (PE), polypropylene is another common type polyolefin which is discussed in the next section. PE is a vinyl polymer and made from ethylene monomer by free radical chain polymerization. As of 2017, more than 100 million tons of PE resins are produced annually and accounting for 34% of total plastic materials in the world [3]. PE is used to make simple plastics n. CH2 = CH2 Ethylene

----- CH2 – CH2 – CH2 – CH2 – CH2 – CH2 -----Polyethylene (PE)

Figure 2.10  Formation of polyethylene from ethylene monomer.

30  Frontiers of Textile Materials materials such as bags, toys, bottles, and thin sheets to high-performance materials such as protection vest for army personnel, sports equipment, bone replacement and many more. Although PE is a thermoplastic polymer, it can be thermoset plastic when cross-linked. German Chemist Hans Von Pechmann first synthesized PE in 1989 [3]. After that a long time it was intact and in 1933 it was again developed during industrial operation by Eric Fawcett and Reginald Gibson at the Imperial Chemical Industries, England. The production of PE was slow in the first few years and after the 1940s the uses of PE begin to expand. In 1959 its production exceeded 1 billion pounds and in 1979 it was 7.9 billion pounds [22]. The Manufacturing Process of Polyethylene Polymer The monomer of polyethylene is ethylene (CH2=CH2) and ethylene is prepared either by the hydrogenation of acetylene or by the dehydration of ethanol. Ethylene also can be produced from petroleum products such as ethane or propane. These saturated hydrocarbons undergo catalytic degradation and dehydrogenation and thus produce ethylene. This process of ethylene formation is known as cracking. Ethylene is gas at normal temperature and boiling point of about −104 °C [2]. PE can be polymerized by two processes, high-pressure high-temperature process and low-pressure low-temperature process. High-Pressure High-Temperature Process In this process, polyethylene is prepared by polymerization of ethylene at 150–200 °C temperature and 1,000–2,000 atmospheres pressure in the presence of oxygen as a catalyst [10]. In the high-pressure high-temperature process the P E is formed in the form of a molten material known as low-density polyethylene and later solidifies to a waxy solid. Low-Pressure Low-Temperature Process In the low-pressure low-temperature process, the high-density PE is produced and the polymerization reaction is carried out at below 100 °C temperature with much lower pressure. This process was developed by professor Karl Ziegler and Giulio Natta by the use of metal oxide such as chromium, aluminum, etc. Types of Polyethylene Polymer Low-Density Polyethylene (LDPE) In LDPE a high degree of short and long branching among polymer chain exists and as a result, the polymer chain cannot pack in a crystal structure

Polymers for Textile Production  31

Figure 2.11  Branched-chain PE.

(Figure 2.11), which is responsible for lower tenacity and higher ductility of LDPE. Its density ranges from about 0.910 g/cm3 to 0.940 g/cm3. LDPE is produced by the free-radical polymerization process. Molten LDPE has a unique flow property. LDPE is used in rigid containers, plastic bags and film wrap. Linear Low-Density Polyethylene (LLDPE) LLDPE is characterized by a density range of 0.915–0.925 g/cm3, and it has a linear polymer chain with considerable short branching. LLDPE has higher tensile strength and lower ductility than LDPE. LLDPE used in toys, lids, buckets, containers, pipes, and cable coverings. High-Density Polyethylene (HDPE) HDPE is a strong, highly dense, stiff polymer with more than the density of 0.941 g/cm3. It has a very low degree of branching, almost linear with the highly crystal structure and hence HDPE has a greater tensile strength (Figure 2.12). It is used in pipe, conduit, extrusion coating, cable insulation, jugs, bottles, and garbage containers. Ultra-High Molecular Weight Polyethylene (UHMWPE) UHMWPE is an extremely dense polyethylene polymer with a very rigid structure. However, due to high rigidity, it cannot pack as like HDPE and has a density range of 0.930 g/cm3 to 0.935 g/cm3 which is lower than HDPE. UHMWPE has outstanding toughness with excellent cut, wear and chemical resistance and hence it is used in a diverse range of products such

32  Frontiers of Textile Materials

Figure 2.12  Straight chain PE.

as can and bottle handling machine parts, parts of weaving machine, bearings, gears, artificial joints, edge protection on ice rinks, gaskets, conveyor belt parts, and butchers’ chopping boards. It is also used in hip and knee replacements and in bulletproof vests. UHMWPE does not melt or flow as like a thermoplastic polymer. The Spinning of Polyethylene Fiber PE fiber is produced by melt spinning technique. The melting temp for LDPE is 205 °C and 210 °C for HDPE. The molten polymer solution is extruded into monofilaments of round, flat, oval, star, triangular, or other cross-sections through a spinneret as fine jets of fiber and is cooled to normal temperature. After that, the monofilaments are passed a series of drawing roller and the draw ratio depends on the end-use of PE. In case of HDPE, the drawing process is carried out at high temperature to ensure more crystallization of PE by the higher degree of drawing, first the monofilaments are heated by hot water at 100–125 °C and then passed over 115– 120 °C heated rollers [10]. Dyeing of Polyethylene Fiber PE fibers cannot be dyed directly with conventional dyeing methods such as dyeing in yarn or fabric form. However, dope dyeing technique, i.e., application of pigments into polymer solution before extrusion through spinneret is a suitable method to produce colored PE fiber.

Polymers for Textile Production  33 Properties of Polyethylene Polymer Chemical Properties All types of PE have excellent resistance to all types of acids and alkalis. Only hot concentrates sulfuric acid and nitric acid attacks and gradually dissolve the LDPE and MDPE [23]. PE also has good resistance to bleaching agents and organic solvents. However, PE swells and may ultimately dissolve in chlorinated hydrocarbons and aromatic solvents such as benzene, toluene, and xylene. Thermal Properties Low melting point is one major disadvantage of PE in many highperformance applications. Normally the softening temperature for LDPE and MDPE is 85–96 °C and 126–132 °C for HDPE and UHMWPE. Brittleness temperature of PE is less than −114 °C, which indicates that PE can retain its flexibility to very low temperature. PE burns slowly and melts prior to propagating flame. Environmental Properties PE is a non-biodegradable fiber and accumulates inland after discharge which is harmful to tree and plants. PE fibers have excellent resistance to insects, bacteria, fungus, mildew, and other microorganisms. Uses of PE Fiber LDPE and MDPE are used to make plastic bags, plastic wrap, squeeze bottles, ropes, cordage, filtration fabrics, and plastic films. HDPE and UHMWPE are used in bottles, buckets, jugs, containers, toys, tarpaulins, protective clothing, curtains, car upholstery fabrics, bulletproof vest, sports equipment, and many more.

2.5.2.2 Polypropylene Polypropylene (PP) with the chemical formula (CH2=CHCH3)n is another member of the polyolefin group’s thermoplastic polymer produced from propylene monomer (CH2=CHCH3). Polypropylene is the lightest polymer among all synthetic polymers and in the second position in uses in the world just after polyethylene (PE) among all plastics [24]. The global demand for PP polymer was about 60 million tons in 2015 and it is expected that it will hit 120 million tons by 2030. Although all properties of polypropylene polymer are similar to polyethylene (PE), polypropylene is slightly harder and better heat resistant due to the presence of a methyl group (CH3) in the monomer. Methyl group of the repeating unit of PP

34  Frontiers of Textile Materials replaces one of the hydrogen atoms of PE’s repeating unit (Figure 2.13). The propylene monomer is flammable nontoxic gas in normal condition and obtained from during the refining process of gasoline. PP was first polymerized by two Philips petroleum chemists J. Paul Hogan and Robert Banks in 1951 [24]. After that in 1954, Professor Giulio Natta from Milan Polytechnic, Italy had polymerized PP to high molecular weight, a crystalline isotactic structure which opened the large-scale commercial production opportunities of PP polymer. PP polymer can be produced in three basic structure by changing the position of methyl groups (CH3), isotactic (Figure 2.14), syndiotactic (Figure 2.15), and atactic polypropylene (Figure 2.16). In isotactic structure, all methyl groups present on the same side of the main backbone axis, while in syndiotactic structure methyl groups present on both sides of the main axis in a regular alternating pattern and in atactic structure methyl groups present on both sides of the main axis in an irregular random pattern. n. CH2 = CH

– CH2 – CH – CH2 – CH – CH2 – CH –

|

|

|

C H3

C H3

C H3

Propylene

| C H3

Polypropylene (PP)

Figure 2.13  Polymerization of polypropylene.

– CH2 – CH – CH2 –CH – CH2 – CH – CH2 – CH – |

|

|

|

CH3

C H3

C H3

C H3

Figure 2.14  Isotactic PP.

C H3

C H3

|

|

– CH2 – CH – CH2 –CH – CH2 – CH – CH2 – CH –

Figure 2.15  Syndiotactic PP.

|

|

CH3

C H3

Polymers for Textile Production  35 C H3

C H3

|

|

– CH2 – CH – CH2 –CH – CH2 – CH – CH2– CH – CH2 – CH – |

|

|

CH3

C H3

C H3

Figure 2.16  Atactic PP.

Isotactic and syndiotactic PP are crystalline in nature; on the other hand, atactic PP is amorphous due to the random and irregular structural pattern of the polymer chain. Isotactic PP is produced commercially in a wide range. The Manufacturing Process of PP Polymer Polypropylene polymer is produced from propylene gas in the presence of catalysts such as Al (iso C4H9)3 and TiCl3 or Al (C2H5)3 and TiCl3. This is an addition polymerization reaction, and the reaction is carried out under 10-atmosphere pressure and below 80 °C. The Spinning of PP Fiber Melting temperature of PP polymer is 163–171 °C, therefore, the melt spinning process is suitable to produce fiber from PP [23]. The melted polymer is extruded through a spinneret to form the fine filaments and after extrusion, the fine jets are subject to a drawing process at high temperature to orient the molecules according to the fiber axis and the fiber crystalline increases as well. After drawing, the filaments are twisted and packaged to form multifilament yarns. Dyeing of PP Fiber Dope dyeing technique suitable for PP fiber. Generally, it is difficult to dye PP fiber in yarn or fabric form. Nevertheless, under precise conditions and in the presence of solubilizing agent disperse dyestuffs can be used to dye PP fiber. Properties of PP Polymer Chemical Properties PP fiber has excellent resistance to acids, alkalis, bleaches and most solvents similar to polyethylene. However, nitric acid can deteriorate the fiber at a high temperature. Above 100 °C the fiber dissolves by xylene, perchloroethylene, and 1,1,2,2 tetrachloroethane.

36  Frontiers of Textile Materials Thermal Properties The melting temperature of PP fiber is 163–171 °C, the fiber softens at 150– 160 °C, and starts to decompose at 290 °C. Environmental Properties PP fiber does not absorb moisture, i.e., hydrophobic in nature and nonbiodegradable. PP fiber also has good resistance against bacteria, mildew, insects, fungi, i.e., the fiber cannot digest by these biological agents. Uses of PP Fiber PP polymer is used to build parts of radio, TV, and refrigerators; package films, pipes, storage tanks, seat covers, bottles, toys, filters, ropes, tapes, twine, and in the automobile industry, apparel textiles, home textiles, and non-woven products. In medical science, non-absorbent suture and transvaginal mesh are produced by PP.

2.5.2.3 Polytetrafluoroethylene Polytetrafluoroethylene (PTFE) is a thermoplastic, vinyl group polymer with (C2F4)n as a chemical formula (Figure 2.17). The main difference with the major vinyl group polymer, polyethylene, is that in polytetrafluoroethylene four hydrogen atoms of the vinyl group have been substituted by fluorine atoms. Teflon is the most common brand name of PTFE produced by Chemours, is a unit of DuPont [25]. Syncolon is also another brand name of PTFE by Synco Chemical Corporation. PTFE shows excellent thermal, chemical and abrasion resistance, low frictional properties with totally hydrophobic nature. PTFE produced from tetrafluoroethylene (TFE) monomer, which is a gas at the normal condition with the boiling point of −76 °C [22]. In today’s, TFE produced by fluorination of chloroform by hydrogen fluoride in a two-step process yielding CHCIF2. This is then dimerized by pyrolysis to provide TFE [22]. In 1938, PTFE was unintentionally invented by the chemist Roy J. Plunkett working at DuPont [25]. The inventor stored a quantity of TFE

F n. CF2 = CF2 Tetrafluoroethylene

F

F

F

F

– C– C–C– C– C– F

F F

F

F

Polytetrafluoroethylene (PTFE)

Figure 2.17  Polymerization of polytetrafluoroethylene (PTFE).

Polymers for Textile Production  37 gas in a cylinder under pressure. After a few days, when he intends to release the gas, he found that the gas had turned into an insoluble, infusible waxy white powder, i.e., TFE gas had polymerized and form PTFE. The new polymer of PTFE attracts the researcher and manufacturer due to its high-performance properties. After 1946, DuPont started marketing of PTFE under the trade name of Teflon. Introduction of Teflon fiber was also started by DuPont in 1954 [10]. It is an expensive fiber and has many special applications over other textile fiber. The Manufacturing Process of PTFE Polymer Generally, PTFE polymer is produced by free-radical polymerization mechanism and suspension or emulsion polymerization technique is used. PTFE in fine powder form is produced by emulsion technique while granules form can be obtained from suspension technique. Polymerization of PTFE is carried out in stainless steel autoclaves under heat and high pressure in the presence of a peroxide type catalyst. The reaction is an exothermic reaction and completed within a short time and gives white powder of PTFE. The newly formed PTFE polymer is then washed and dried. The Spinning of PTFE Fiber PTFE is a highly crystalline polymer and its melting point is also high around 330 °C and the polymer begins to decompose before melting. Again, PTFE polymer is not soluble in any commonly used solvents. So, melt spinning, dry spinning, and wet spinning technique are not applicable for spinning fiber from PTFE polymer. The dispersion spinning mechanism, a special method for the infusible and insoluble polymer is used to produce textile fiber from PTFE polymer. In this method, the disperse solution of PTFE is extruded through a spinneret and sintered at 385 °C to fuse the polymer particles to coalesce into a continuous fiber. Properties of PTFE Polymer Chemical Properties PTFE fibers have extraordinary resistance to all types of acids, alkalis and most solvents. Only a few perfluorinated organic liquids can dissolve PTFE at above 299 °C. PTFE fibers cannot dye at all. Thermal Properties PTFE fiber has the best thermal stability among all known synthetic fibers. The melting point of PTFE fiber is around 330 °C and the polymer begins to decompose before melting. The useful temperature of the PTFE polymer is (−73 to 275) °C.

38  Frontiers of Textile Materials Environmental Properties PTFE fiber is 100% hydrophobic in nature and does not absorb any moisture and non-biodegradable fiber. The PTFE fiber does not attack by any types of insects and microorganisms and inert in sunlight. Uses of PTFE Fiber The PTFE is an inert polymer in all conditions and medium and therefore it has numerous high-tech and industrial applications. PTFE used in the coating in non-stick frying pans and other cookware, braided packing, filtration fabrics, gaskets, laundry pads, conveyor belt, electrical tapes, corrosion resistance cordage, electrical insulator, and water-repellent composites. Teflon fibers are also used in the aerospace and aviation industry.

2.5.2.4 Poly Vinyl Chloride Polyvinyl chloride (PVC) with the chemical formula (–CH2–CHCl–)n, is a polymer of the thermoplastic group, polymerized from vinyl chloride, a widely used plastics and rigid, inert and non-toxic polymer. In commercial trade, the PVC is known as vinyl resins. The production of the vinyl resin increases with the increasing demand. In 2013, the global production of PVC was 53 million ton and it had reached 61 million ton in 2016 [26]. PVC is made from vinyl chloride also known as chloroethylene (CH2=CHCl) (Figure 2.18) and used in a versatile range of products such as siding, windows, wiring, cables, pipes, household products and a much smaller scale in textile fiber. PVC was first polymerized by French chemist Henri Regnault in 1838 but it was not patented. After the first world war, Waldo Lunsbury Semon, an American chemist working in B. F. Goodrich Company, prepared and patent the plasticized PVC. The flexible, inert natures of the PVC polymer unravel the versatile applications of PVC in a different arena. The Manufacturing Process of PVC Polymer The monomer of the PVC polymer is vinyl chloride (CH2=CHCl) which is a gas with a boiling temperature of –14°C. Vinyl chloride is produced by

n. CH2 = CH

–CH2 – CH – CH2 – CH – CH2 – CH –-

|

|

|

|

Cl

Cl

Cl

Cl

Vinyl chloride

Polyvinyl chloride (PVC)

Figure 2.18  Polymerization of vinyl chloride polymer.

Polymers for Textile Production  39 CH2Cl – CH2Cl CH CH + HCl

500ºC Pressure 150ºC Catalyst

CH2=CHCl + HCl CH2=CHCl

Figure 2.19  Formation of vinyl chloride.

two methods (Figure 2.19): i) by cracking ethylene dichloride in the vapor phase or ii) by reacting acetylene with hydrogen chloride. In the industrial production process, 80% of polyvinyl chloride is produced by the suspension polymerization process. Emulsion and bulk polymerization process are also used on a smaller scale to produce PVC polymer. Suspension and bulk polymerization process are carried out at (50–80) °C temperature whereas the emulsion polymerization process required lower temperature (around 20°C). In normal condition vinyl chloride is a gas, so the all polymerization process is needed to be conducted in a pressure reactor or an autoclave. The Spinning of PVC Fiber The spinning of PVC fibers can be carried out by melt or dry spinning process. Melting temperature of PVC polymer is (120–130) °C and begins to decompose at about 200 °C. So, the spinning temperature should be kept below 200 °C. This method is not suitable for the production of very fine filament fiber. The dry spinning process is more convenient to produce much finer yarn than melt spinning and used exclusively to produce commercial-grade textile fiber. In the dry spinning process, acetone or carbon disulphide is used as solvents to dissolve PVC polymer. The polymer solution is pumped through spinnerets at (70–100) °C. The solid jets of filaments come forward into a hot air stream to evaporate the solvent to release the solid filaments of PVC. The solvents can be recovered and reused. Types of PVC Fiber There are three types of PVC fiber: Polyvinyl chloride fiber (contains 100% vinyl chloride units); Vinyl chloride copolymer fiber (contains at least 85% vinyl chloride); chemically modified polyvinyl chloride (another name chlorinated polyvinyl chloride, contains less than 20% vinyl chloride and more than 80% vinylidene chloride units). Dyeing of PVC Fiber Dope dyeing technique can be used to obtain colored PVC filaments. Again, PVC fibers can be dyed with disperse dyes at 70°C in the presence of carrier of swelling agents.

40  Frontiers of Textile Materials Properties of PVC Polymer Chemical Properties PVS polymer and fiber have excellent resistance to all acids, alkalis, bleaching agents, reducing agents, and oxidizing agents. For example, the PVC fiber will remain unharmed after 4 years’ stepping in nitric acid, sulfuric acid or caustic soda. Besides these, PVC fiber does not affect by alcohols, ether, and petroleum hydrocarbon but the PVC fiber will swell and attack by phenols, toluene, trichloroethylene, benzene, and acetone. Thermal Properties Melting temperature of PVC polymer is 120–130°C and decomposition begin at about 200 °C. PVC fibers are non-flammable and will not burn. The PBC fiber will disintegrate when subjected to continue flame. Environmental Properties PVC fibers are non-biodegradable and have complete resistant to insects and microorganisms. The fiber does not swell in water and water absorption is actually nil. Uses of PVC Fiber PVC polymer used in siding, windows, water pipes, wadding’s, filter cloths, braiding, battery fabrics, awnings, curtains, artificial limbs, billiard clothes, accessories for different machinery, and so on.

2.5.2.5 Poly Vinylidene Chloride The polyvinylidene chloride obtains from the vinylidene chloride monomer and has the following structure of [–CH2–CCl2–]n. The vinylidene chloride generally produces from trichloroethane as shown in Figure 2.20. The polymer is formed by radical polymerization process and emulsion technique is used. The crystalline portion of this polymer is high due to its symmetrical structure. The fiber of this polymer is produced by melt spinning technique as its melting point is around 170°C. Polyvinylidene chloride polymers are extensively used as textile fibers. The fibers have 400ºC CHCl2 CH2Cl

CH2=CCl2 + HCL Pyrolysis

Figure 2.20  Formation of vinylidene chloride.

Polymers for Textile Production  41 properties like good resistance to abrasion, light, chemicals, and soil. The fiber can be dope dyed but cannot directly dye in yarn or fabric form because of its high crystalline structure.

2.5.2.6 Polyamide Polyamide (PA) is a long-chain synthetic polymer where amide linkage (–CO–NH–) links the repeating units and hence called polyamide. There are different types of polyamides from which textile fibers can be developed. Nylon is the generic term for fibers of polyamide derivatives. Nylon is the long-chain synthetic polymeric amide consisting of recurring amide groups as an integral part of the main polymer chain. This polyamide can be formed into a filament in which the structural elements are oriented in the direction of the axis [23]. Polyamide polymer was discovered by W. H. Carothers, a prominent American chemist, in 1931 during researching for polyesters and polyamides. The first commercial polyamide fiber was nylon 6.6 and introduced by DuPont in 1938 [4]. After that nylon (especially nylon 6 and nylon 6.6) becomes one of the most important apparels and engineering materials. In 2016, the global production of polyamide polymers was 7.8 million tons of which nylon 6 was 4.4 million tons and nylon 6.6 was 3.4 million tons [4]. Polyamide polymers are produced by the condensation reaction between a dicarboxylic acid and di-amine. Polyamides generally have the following chemical structure: [–N–R1–N–C–R2–C–]n





H





H O

O

where R1 and R2 are aliphatic and/or aromatic residues, i.e., –CH2- or According to the chemical structure polyamide fibers are three types: 1. A  liphatic polyamide: Normally fibers of nylon series are included in this group and contain no aromatic or benzene ring in their structure. Aliphatic polyamides are produced on a greater scale than other polyamides and the most important class of engineering thermoplastics. 2.  Semi-aromatic polyamide: This semi-crystalline thermoplastic resin types polymer also known as polyphthalamides (PPA) and produced from the condensation reaction

42  Frontiers of Textile Materials between hexamethylene diamine and terephthalic acid. The aromatic portion consists of a total of 55% of the polymer chain [27]. 3. Aromatic polyamide: The aromatic polyamides known as aramids and consists of totally aromatic structure. The fully aromatic structure is responsible for their high melting temperature, ultra-high tensile strength, excellent solvent, heat, and flame resistance. The two most important aramid fibers are poly (p-phenylene terephthalamide) also known as Kevlar, and poly (m-phenylene isophthalamide) also known as Nomex [27]. Types of Nylon Fiber 1. N  ylon 6: Nylon 6 polymer is produced by ring-opening polymerization (self-condensation reaction) of a single monomer named caprolactam. Caprolactam is a white crystalline compound and prepared from cyclohexanol or phenol. n. CH2(CH2)4CONH → ---- NH (CH2)5 CONH (CH2)5 CONH (CH2)5 ---Caprolactam

Nylon 6

Polycondensation or polyaddition mechanism are used to polymerize caprolactam in the presence of water to open the ring structure of caprolactam. An autoclave or a reactor is used during the polymerization process. Nylon 6 fiber can be produced as monofilaments, multifilament, staple or tow form. 2. Nylon 6.6: Nylon 6.6 fiber is produced from two monomers, one is di-amine and another one is di-­carboxylic acid. Each monomer has six carbon atoms in their chemical structure and hence represents by two number, nylon 6.6. n. NH2 (CH2)6 NH2

+

n. HOOC (CH2)4 COOH

Hexamethylene diamine ↓

Adipic acid

--CONH(CH2)6NHCO (CH2)4CONH (CH2)6NHCO (CH2)4 CO---Polyhexamethylene adipamide

Polymers for Textile Production  43

Nylon 6.6 polymer obtained by a condensation polymerization process in an autoclave. Nylon 6.6 fiber can also be produced as monofilaments, multifilament, staple, or tow form. Nylon 6.6, as well as nylon 6 fibers, are the two most commonly used fibers in the polyamide field.

3. N  ylon 4: Nylon 4 is synthesized by the self-polymerization of 2-pyrrolidine. Although other polyamide fiber can be produced by melt spinning technique, nylon 4 is a dry spun fiber because it is not stable at its melting (262 °C) temperature. n. NH–(CH2)3–CO → ----- (CH2)3–CO–NH ----2-pyrrolidone

Nylon 4

4. N  ylon 7: Nylon 7 also known as Enant fiber and developed in Russia. Nylon 7 is produced from the lactam of heptanoic acid by the condensation polymerization process. Nylon 7 is a melt-spun fiber. 5. Nylon 11: Nylon 11 is also a self-polymerized fiber with the commercial name Rilsan. The monomer of nylon 11 is w-amino undecanoic acid which is extracted from castor oil. The polymerization process is of the polycondensation types. n. NH2– (CH2)10–COOH → ---- NH–(CH2)10–CO----w-amino undecanoic acid

Nylon 11

Its melting temperature is 188 °C and it is a melt-spun fiber. 6. Nylon 6.10: Nylon 6.10 is prepared from the hexamethylene diamine and sebacic acid by the polycondensation reaction. It is also a melt-spun fiber and its melting temperature 215°C. n. NH2 (CH2)6NH2 + n. HOOC (CH2)8COOH Hexamethylene diamine

↓

Sebacic Acid

----- HN (CH2)6 NHCO (CH2)8 CO -----Nylon 6.10

7. N  ylon 12: Nylon 12 is also a melt-spun fiber like other nylon fibers and the monomer is dodecalactam which is produced

44  Frontiers of Textile Materials from butadiene. The melting temperature of nylon 12 is 175°C. Nomenclature of Nylon Fiber Generally, nylon fibers are represented by a numbering system. This number indicates the number of carbon atoms in its monomer molecules. Nylons made by the self-polycondensation reaction from a single monomer are represented by a single number such as nylon 6, nylon 4, nylon 7, nylon 11, nylon 12, etc. On the other hands, nylons (nylon 6.6 and nylon 6.10) produced from two monomers, di-amine and di-carboxylic acids are represented by two number. The first one represents the number of carbon atoms in the diamine and the second number for di-carboxylic acids. Thus, nylon 6.10, where 6 and 10 represent the number of carbon atoms of hexamethylene diamine and sebacic acid, respectively. The Spinning of PA Fiber Nylon fibers have a melting temperature range of (200–300) °C and all types nylon fiber can be produced by melt spinning process except nylon 4 which is a dry spun fiber because it is not stable at melting temperature (262 °C). Dyeing of nylon Fiber Nylon fibers have an affinity to different types of dyestuffs and can be dyed with direct, acid, metal complex, chrome, reactive, disperse, and pigments. Among them, only acid and disperse dyes are commercially preferable for their good performance in fastness criteria. Properties of PA Polymer Physical Properties Nylon 6.6 Tensile strength is of 4,200–4,620 kg/cm2 for staple fiber and 4,550–5,950 kg/cm2 for regular filament fiber, respectively. Elongation is 37–40% for staple fiber and 26–32% for regular filament fiber, respectively. Nylon fiber is elastic in nature. Regular Nylon 6.6 filament has a recovery of 100% at up to 8% extension. Nylon 6 Tensile strength of Nylon 6 is 5,110–5,880 kg/cm2 for regular filament fiber. Elongation of that fiber is 23–50% for staple fiber and 23–42.5% for regular filament fiber, respectively. Regular Nylon 6 filament has a recovery of 100% at up to 6–8% extension and 85% recovery at up to 10% extension.

Polymers for Textile Production  45 Chemical Properties Nylon 6 fiber degraded by mineral acids but have good resistance to weak acids and alkalis. It dissolves in concentrated formic acid, phenol and cresol. Nylon 6.6 fiber has more resistance to acids and alkalis in comparison with nylon 6. The fiber dissolves in concentrated hydrochloric acid, sulfuric acid, and nitric acid with some decomposition. The fiber also insoluble in all organic solvents but dissolves in phenol and cresol [23]. Thermal Properties The melting temperature of nylon 6 and nylon 6.6 fibers is (213–220) °C and (249–260) °C, respectively. The glass transition temperature of both fibers is in the range of (29–42) °C. Environmental Properties Nylon 6 and nylon 6.6 fibers both are non-biodegradable fiber and have excellent resistance to all biological agents but both fibers are degraded by prolonged sunlight exposure with strength loss. Moisture regain of nylon 6 and nylon 6.6 are same which is 4–4.5 %. Uses of PA Fiber Aliphatic polyamides are widely used in engineering and industrial applications, such as wire and cable jacketing, cooling fans, air intake, turbo air ducts, valve and engine covers, brake and power steering reservoirs, gears for windshield wipers, and speedometers. Nylon fibers also used for power tool housings, valves, and vending for different machines and pumps and for many electrical/electronic parts including switches, sockets, plugs, and antenna mounting devices [27]. Besides the engineering and industrial applications, nylon fibers also used for making apparel items such as hosiery products, lingerie items, gloves, socks, hunting apparel, outerwear, etc. Aromatic Polyamides: Kevlar and Nomex Aromatic polyamides also are known as aramids and produced by replacing aliphatic segments of aliphatic polyamides by aromatic units. In the aramid fiber, the polymer chain is highly oriented along the fiber axis and this configuration is responsible for the higher strength with a high melting point of aramid fiber. According to Federal Trade Commission, aramid fiber can be defined as “A manufactured fiber in which the fiber forming substance is a long-chain synthetic polyamide in which at least 85% of the amide ­linkages (–CONH–) are attached directly to two aromatic  rings”  [28].

46  Frontiers of Textile Materials H2N

NH2

ClOC

COCl

+

H NH

N

O C

C

O

n

Figure 2.21  Preparation of Nomex fiber. H H2N

NH2 + ClOC

COCl

O

N

N C

H

O

C n

Figure 2.22  Preparation of Kevlar fiber.

The two most important aramid fibers are Meta aramid with trade name Nomex and Para-aramid with the trade name Kevlar. The first commercial production of meta-aramid fiber was in 1960 by Du Pont with the trade name Nomex [28]. Nomex fiber is characterized by excellent heat resistance, it neither melts nor ignites. Another important Para-aramid fiber, named Kevlar with much higher tenacity and elastic modulus was introduced by Du Pont in 1973 [28]. The global aramid fiber market was USD 2.91 billion in 2017, and it is expected that it will reach USD 5.62 billion at the end of 2014 [29]. Aramid fibers are produced by the self-condensation of aromatic amino acids or by polycondensation reaction between aromatic diacid chlorides and aromatic diamines. Nomex fiber is produced from isophthaloyl chloride and m-phenylene diamines (Figure 2.21). On the other hand, Kevlar fiber is produced by terephthaloyl chloride and p-phenylene diamines (Figure 2.22). Both fibers are dry spun as their melting temperature is too high for the melt spinning process. Properties of Nomex and Kevlar Fiber These fibers are also known as a high-performance fiber because of their extraordinary characteristics. The properties of Kevlar and Nomex fiber are shown in Table 2.1 as a comparison. End Uses Because of high strength and stiffness, aramid fibers are considered as replacement of metal. Aramid fibers are used in aerospace and military applications, for ballistic-rated body armor fabric and ballistic composites, in bicycle tires, protective apparels, thermal and electrical insulation, marine cordage, marine hull reinforcement, and as an asbestos substitute. The composites of graphite and Kevlar are used in Boeing 757 and Boeing 767 planes.

Polymers for Textile Production  47 Table 2.1  Properties of Kevlar and Nomex fibers [23]. Kevlar fiber

Nomex fiber

Density (g/cc)

1.45

1.38

Melting temperature (°C)

500

390

Solvent

Sulfuric acid

Sulfuric acid

Tenacity (g/day), dry state

8–22

6–12

Tenacity (g/day), wet state

7–21

5–11

Elongation (%)

8–20

20–30

Recovery (%)

100

100

Moisture regain (%)

3.0

3.5

2.5.2.7 Polyethylene Terephthalate Polyethylene Terephthalate (PET) is an important thermoplastic polymer made by the condensation reaction between a dibasic acid and dihydric alcohol. The polymer chain of PET contains ester groups (–COO–) to link the monomer molecules and hence this polymer is termed as ­polyester. According to Federal Trade Commission, polyester fiber is defined as “a manufactured fiber in which the fiber forming substance is any longchain synthetic polymer composed of at least 85% by weight of an ester of dihydric alcohol and terephthalic acid”. As a plastic material, polyester is in the third position with 18% market share just after polyethylene (33.5%) and polypropylene (19.5%) [28]. The study for PET polymer was started by the renowned chemist Wallace H. Carothers of Du Pont during his investigation for polyamide. PET was overshadowed by the invention of nylon fiber. In 1942, J. T. Dickson and J. R. Whinfield of the Calico Printers Association in England again discovered PET fiber by condensing ethylene glycol with terephthalic acid [10]. After the second world war, the commercial development of polyester fiber was started by I.C.I Ltd. in the UK and Du Pont in the USA with the trade name “Terylene” and “Dacron”, respectively. Polyester fiber has the following general structure:

[—O—(R)—O—C—(R1)—C—]n



O

O

48  Frontiers of Textile Materials [- O- (CH2)2 -OOC - (CH2)6 – CO-]n

Figure 2.23  Aliphatic polyester.

[- O-(CH2)2- OOC -

-CO-]n

Figure 2.24  Aromatic polyester.

when R and R1 both are aliphatic, polyester fiber will be fully aliphatic and these aliphatic polyesters are not usable because of their low melting temperature (65°C). This problem was overcome by introducing an aromatic ring, i.e., benzene ring into the PET polymer chain and it will be semi-aromatic polyester fiber. The incorporation of the aromatic ring increases the stiffness of the polymer chain. As a result, the melting temperature of semi-­aromatic PET fibers increases up to 265°C [2]. Figures 2.23 and 2.24 show the chemical structures of aliphatic and aromatic PET, respectively. The Manufacturing Process of PET Polymer PET is prepared by the condensation reaction between ethylene glycol with terephthalic acid or its derivatives such as dimethyl terephthalate. At first, ethylene is produced by cracking of oil received from petroleum. Then ethylene oxide is produced by oxidizing ethylene and then hydrated to produce ethylene glycol (Figure 2.25). On the other hand, para-xylene obtained by distillation process from petroleum is used for the production of dimethyl terephthalate (Figure 2.26). This para-xylene is oxidized in the presence of nitric acid or air to produce terephthalic acid, which later produces dimethyl terephthalate by esterification with methyl alcohol. PET polymer is produced by the condensation reaction between the ethylene glycol and terephthalic acid or dimethyl terephthalate with releasing water or methyl alcohol, respectively. The polymerization reaction is carried out at high temperature (200–250)°C (Figures 2.27 and 2.28).

CH2 CH2 Ethylene

oxidation

CH2 CH2 Ethylene Oxide

Figure 2.25  Formation of ethylene glycol.

Hydration

O

CH2OH CH2OH Ethylene Glycol

Polymers for Textile Production  49 CH3

COOH

COOCH3

COOH

COOCH3

Petroleum

CH3

Terephthalic Acid

(P-Xylene)

Dimethyl Terephthalate

Figure 2.26  Formation of dimethyl terephthalate.

n. HOOC-COOH + n. HO-(CH2) 2-OH Terephthalic Acid Ethylene Glycol -COO - (CH2)2 –O- ]n-H + (2n-1) H2O

HO-[OC-

Polyethylene Terephthalate polymer

Figure 2.27  Formation of PET polymer from terephthalic acid.

n. CH3O.OC-

-CO.OCH3

+

Di methyl Ester of Terephthalic Acid CH3O-[OC-

n. HO-(CH2)2-OH Ethylene Glycol

-COO-(CH2)2 –O -]n-H + (2n-1) CH3OH Polyethylene Terephthalate polymer

Figure 2.28  Formation of PET polymer from dimethyl terephthalate.

The Spinning of PET Fiber The melting temperature of the PET polymer is 260 °C and the molten polymer is stable as long as oxygen is rigorously expelled. So, the melt spinning technique is suitable to produce polyester fiber. The spinning process is similar to polyamide fiber. The molten polymer pumped through a spinneret and the emerged filaments are collected into packages after solidification and drawing. Polyester fibers can be produced as monofilament, multifilament, staple or tow form. Dyeing of PET Fiber Polyester is a hydrophobic fiber and the dyeing should be carried out with hydrophobic dyes at high temperature. Disperse dyes and azoic dyes can be used to dye polyester fiber. Commercially azoic dyes are not feasible due to multiple application stages. At present disperse dye is unique to dye polyester fiber. Normally dyeing of polyester fiber is carried at high temperature (130–140) °C and pressure under mild acid conditions.

50  Frontiers of Textile Materials Properties of PET Polymer Physical Properties Tensile properties vary for different types and forms of PET. Tensile strength is 7,350–8,750 kg/cm2 for high tenacity filament and 4,900–5,950 kg/cm2 for medium tenacity filament, 5,250–7,350 kg/cm2 for high tenacity staple and 4,900–5,950 kg/cm2 for medium tenacity staple. Elongation: 8–11% for high tenacity filament and 15–30% for medium tenacity filament; 20–30% for high tenacity staple and 30–50% for medium tenacity staple. Elastic recovery: At 2% extension recovery is 90–96%, and at 5% extension recovery is 80–90%. The polyester fiber begins to soften at 225–230°C and melts at (255–265)°C. Chemical Properties Polyester fibers have good resistance against organic acids and the fiber only degrades and dissolves in concentrated sulfuric acid. The fibers also have resistance to weak alkalis and it becomes weak in strong alkalis. But the fiber has superior resistance to all bleaching agents and organic solvents. Polyester is an extremely hydrophobic fiber and its moisture regain is only 0.4%. The fibers have outstanding resistance to all biological agents, insects, mildew, and moth. Uses of PET Fiber Polyester fiber is widely used in filament or staple form to make apparels. In blending with natural cellulosic fiber, i.e., in CVC or PC form, polyester fibers have extensive uses. Polyester is also used in threads, ropes, home furnishing, and in industrial fabrics.

2.5.2.8 Polyacrylonitrile Polyacrylonitrile (PAN) is also a vinyl group polymer with the chemical formula of (–CH2–CHCN–)n. In the polymeric structure of PNA, one hydrogen atom of the vinyl group (CH2=CH2) has replaced by the cyanide (–CN) group, therefore, this polymer is also known as polyvinyl cyanide. PAN polymer is produced from the acrylonitrile (CH2–CHCN) monomer and acrylic fiber contains at least 85% acrylonitrile units in their polymeric structure shown below: n CH2= CH–CN → –(CH2–CHCN–)n

Polyacrylonitrile (PAN)

In Germany, PAN was first produced by Moureu in 1893. After that PAN remained as a laboratory curiosity for a long time. In 1930, PAN was again synthesized by another German chemist Hans Fikentscher and Claus

Polymers for Textile Production  51 Heuck [30]. The American chemical conglomerate DuPont was first started mass production of PAN fiber in 1946 with the brand name Orlon [30]. The Manufacturing Process of PAN Polymer PAN polymer manufactured from acrylonitrile monomer. Acrylonitrile mainly produced from acetylene. Hydrogen cyanide and acetylene are used to produce acrylonitrile at (80–90)°C in the presence of ammonium chloride as a catalyst. CH≡CH + HCN → CH2=CH–CN

The polyacrylonitrile polymer is formed by addition polymerization process from acrylonitrile monomer and the polymerization is started by a free radical mechanism. The Spinning of PAN Fiber The PAN fiber can be produced by the three spinning processes of manmade fiber: melt spinning, dry spinning, and wet spinning technique. But commercially melt spinning process is not practiced as the stable phase of molten PAN polymer is not easy to obtain. In the dry spinning process, dimethylformamide is used as a solvent, and in wet spinning process dimethylacetamide, dimethyl sulfoxide, nitric acid, and zinc chloride can be used as a solvent along with dimethylformamide. Dyeing of Acrylic Fiber Acrylic fiber is an entirely synthetic polymer and it was difficult to dye in the early stage of development. Now a wide range of basic dyes and disperse dyes are available to dye the acrylic fiber. Dope dyeing with pigments or dyes technique is also applicable to produce colored fiber. Properties of PAN Polymer Physical Properties It has a tensile strength of 2,100–3,150 kg/cm2 for staple fiber and 3,500– 5,250 kg/cm2 for filament fiber, respectively. It can be elongated to 20–55% for staple fiber and 30–36% for filament fiber, respectively. The elastic recovery of PAN fiber is 90–95%. Chemical Properties Acrylic fibers have excellent resistance to acids, alkalis, oxidizing agents, and reducing agents. It can only be attacked by strong acids and slowly hydrolyzed by weak bases. Acrylic fiber is a non-biodegradable fiber and is not attacked by microorganisms and insects. Its moisture regain is 1–3%.

52  Frontiers of Textile Materials Thermal Properties The PAN fibers have a high melting point, (330–340)°C but it starts to decompose before melting temperature. The fiber softens and sticks at 150°C and 245°C, respectively, and the glass transition temperature is 100°C. Uses of PAN Fiber Acrylic fibers have a wide range of applications. It is used to produce knitted outerwear, carpets, furnishing fabrics, outdoor fabrics, flocking for flock print, tufting, paper, core-spun yarns, etc.

2.5.2.9 Modacrylic Fiber Modacrylic fiber is a copolymer consisting of less than 85% but at least 35% acrylonitrile units. A second monomer is used along with acrylonitrile to produce modacrylic fibers. Such as Vinyon N is a modacrylic fiber with 60% vinyl chloride and 40% acrylonitrile combination. Teklan is also a modacrylic fiber from the acrylonitrile–vinylidene copolymer. Modacrylic fibers can be produced by dry or wet spinning technique. Such as Vercel is a dry spun fiber and Dynel is a wet spun staple fiber. The melting temperature of modacrylic fiber is (200–210)°C and moisture regain is 4%. Chemical properties of modacrylic fibers are similar to acrylic fibers. Modacrylic fibers also soluble in ketones like acetone. Modacrylic fibers are used in children’s sleepwear, blankets, carpets, fur fabrics, rugs, and wigs.

2.5.2.10 Spandex Fiber Spandex is an elastic type fiber which has an extension at a break in excess of 200% with rapid recovery when the tension gets released. Spandex is also called elastomeric fiber because it is produced from an elastic type polymer, called polyurethane which has stretchability like natural rubber. Spandex fiber can be defined as “a manufactured fiber in which the fiber forming substance is a long-chain synthetic polymer compromised of at least 85% of segmented polyurethane” [31]. Joseph C. Shivers, a scientist of Du Pont had invented the elastomeric fiber for the first time and Du Pont started its commercial production in 1960 with the trade name Lycra [27]. The polymer of elastomeric fiber consists of two segments, named soft and hard segments (Figure 2.29). The soft segments oriented in random style with minimum crystallinity and the molecular chains of these segments are coiled by folding on themselves. The stretchability and flexibility of spandex fiber are due to for these soft segments. On the other hand, the hard segments are clung to each other by strong hydrogen bonding.

Polymers for Textile Production  53 Soft segment

IXIXIXI

IXIXIXIXI

Hard segment

Hard segment

Figure 2.29  Molecular configuration of Spandex fiber.

[- C - N - R1- N – C – O - R2 – O - ]n O H

H

O

Figure 2.30  Chemical structure of polyurethane fiber.

When stretched, the coiled soft segments get opening out more than 200% to their original length and the hard segments prevent the fiber breakage. The flexible extended soft segments slip back into their original configuration when the load is removed. Chemically spandex is a polymer of urethane (–NH–COO–). This is 100% synthetic fiber (Figure 2.30). Some of the polyurethane fibers are now on the market. In Britain, Courtaulds has marked “Spanzelle”. “Vyrene” is made by Dunlop Rubber Co. and Du Pont has made “Lycra”. The Spinning of Spandex Fiber Spandex fiber can be spun by melt spinning, dry spinning or wet spinning. For dry and wet spinning dimethylformamide is used as a solvent. Melt spun technique is also suitable as its melting temperature is in the range of 175–178°C. Properties of Spandex Fiber Physical Properties It has a density of 1–1.05 g/cc which is close to the water density. Melting temperature of spandex is in the range of 175–178°C. Its excellent elongation value can be as high as 700%. The elongation at break generally falls in between 350% and 700% with an elastic recovery of 99% at 200% extension. However, the elastic modulus is very low and lies in the range of 0.007–0.020 g/day. Chemical Properties The fibers are well resistant to alkalis but prone to yellowing in acid solution. The fibers are also resistant to peroxide bleaching, ozone, chlorine, and UV radiation. Disperse dye, acid dye and basic dye can be used for the

54  Frontiers of Textile Materials coloration of spandex fiber. The water absorption capacity of this fiber is low (moisture regain=1.3%). Uses of Spandex Fiber Spandex fiber can be used as accessories in belts, gloves, socks, tights; in sportswear like swimwear, cycling jersey, apparel for exercise; in apparel like leggings, shorts, skinny jeans, ski pants, yoga pants, brassieres, hosiery, surgical hose, etc.

2.6 Polymers in Textile Processing There are several applications of polymers in textile processing other than fiber formation including in the sizing of warp yarn for weaving. PVA and starch are widely used as sizing ingredients in the preparation of sizing. One other important application of polymers in textile processing can be found in the printing of textiles as a thickener. Thickener is a colorless viscous paste which is made from one or more thickening agents. Thickeners are an adhesive substance used for making viscose paste for screen printing. Sodium alginate has been using as a textile thickener for a long time and discussed here.

2.6.1 Polyvinyl Alcohol Polyvinyl alcohol (PVA) is a synthetic and vinyl group polymer with the major difference which is unlike other synthetic polymers, PVA is a water-soluble polymer. In the PVA, one hydrogen atom of the vinyl group (CH2=CH2) has replaced by hydroxyl (–OH) group and hence it is water-soluble and as a result, few properties of PVA fiber are similar to cotton fiber. PVA dissolves slowly in cold water but it dissolves rapidly in high temperature and above 90°C it dissolved completely [22]. It is an odorless, tasteless, translucent granular powder. Another important characteristic of PVA polymer is that like other polymers, PVA is not polymerized from its monomer, vinyl alcohol (CH2=CHOH). Vinyl alcohol is unstable, therefore, PVA is indirectly made by the hydrolysis of polyvinyl acetate. Polymerization of PVA is given in the (Figure 2.31). In 2016, the global PVA market size was about USD 714.5 million and it is expected that it will reach USD 1.2 billion by 2025 [32]. In Germany, PVA was first polymerized in 1924 and first PVA fibers were produced in 1931 by Wacker–Chemie G.m.b.H. under the trade name of “Synthofil”.

Polymers for Textile Production  55 n CH2 = CHOCOCH3 + n CH3OH →- (CH2 – CH-)n

+ n CH3COOCH3

OH

Figure 2.31  Polymerization of PVA.

The Manufacturing Process of PVA Polymer As vinyl alcohol is unstable, PVA is made by the hydrolysis of polyvinyl acetate. Vinyl acetate is made by the reaction of acetylene or ethylene with acetic acid as follows: CH ≡ CH + CH3COOH → CH2 = CHOCOCH3 Acetylene

Acetic Acid

Vinyl Acetate

The vinyl acetate is polymerized by dissolving in methanol and in presence of a catalyst (such as peroxide or azo-compound) to form PVA polymer. The Spinning of PVA Fiber PVA fiber can be generally produced by wet spinning technique. PVA polymer dissolved in water to form 15% solution and then the solution pumped through a spinneret into a coagulating bath of sodium sulfate solution to form the filament fiber. PVA fiber can also be produced by dry spinning technique. In dry spinning, 30–50% concentrated polymer solution passed through a spinneret and the fiber jets emerge into hot air to produce the solid filaments. In both dry and wet techniques, the filament fibers are drawn at a high temperature around 240°C to improve the fibers water resistance by increasing the fiber compactness. Properties of PVA Polymer Chemical Properties PVA fiber is generally resistant to normal acids and alkalis but shrinks by hot or concentrated acids and starts yellowing by strong alkalis without affecting the tenacity. PVA polymer is dissolved by phenol, cresol, and formic acid. Having hydroxyl groups in the polymer structure, the dyeing behavior of PVA fiber is similar to cotton fiber. The PVA fiber can be easily dyed with reactive, direct, vat, sulfur, acid, and basic dyes. Physical Properties PVA fiber begins to turn into yellowish at 220°C and shrinks and softens at a temperature range of 230–250°C. Moisture regain percentage of

56  Frontiers of Textile Materials water-soluble filament fiber is 9%. The PVA fibers have complete resistance to insects and microorganisms. Uses of PVA Fiber PVA polymer is mainly used as sizing agents for warp yarn. It is also used in curtains, upholstery, carpets, umbrella, tablecloths, sheets, and so on.

2.6.2 Starch Starch is a bio-degradable polymer and major carbohydrate reserve in a plant. It is a hydrophilic polymer composed of a linear and branched-chain. The polymer chain structure is shown in Figure 2.32. The linear polymer is called amylose and the branched polymer is called amylopectin. Starch can be digested by human compared to cellulose which is indigestible and considered one of the main sources of energy for sustaining. Not only food items i.e., potato, rice, bread etc., starch has been getting extreme importance for using in non-food application also, e.g., glue for paper industry and gum in textile industries [11, 33–35].

2.6.3 Sodium Alginate Sodium alginate is a derivative of alginic acid. Sodium alginate is collected from brown algae which contain approximately 30% to 60% alginic acid. Figure 2.33 shows the chemical structure of sodium alginate. Alginic acid is converted to sodium alginate by treating with alcohol and sodium carbonate, which allows it to be water-soluble. Sodium alginate has a long history of using as a thickening agent in textile printing. It is mostly useful for making HO

HO HO

OH

O

HO OH

OH

OH

OH

OH

HO

HO OH

O

OH

OH

Figure 2.32  Starch polymer chain.

O

HO O

OH

O

O

O

O

O

O

O

O

HO

O

OH

OH

O

O OH

OH

Polymers for Textile Production  57 COO H

O

H O

H OH

H

OH

H

O

OH

H HO

H H

H

O

n

O

NaOOC

Figure 2.33  Chemical structure of sodium alginate.

paste while printing with reactive dyes. It has no effect on dye fiber reaction as a result, bright clear printing with good hand feel can be achieved [36].

2.7 Conclusion Polymers initially perceived as a compound of the chemical industry are now strongly associated with the field of plastics, fibers, elastomers, and engineering. The last decades have shown an increasing interest of polymers in many advanced fields of material sciences including high-performance fiber. It is growing rapidly in providing new materials for engineering field during the last century where fiber is a significant player followed by elastomers. Textiles are made of polymers. To understand textile products, their performance and functionality it is essential to study the polymers that make the textiles. A polymer is made of monomers. This chapter discussed the polymerization process of the most common polymers used in fiber production. Polymers can be natural or manmade. Natural polymers are more complex in structure, varied in properties and not unlimited. Manmade or synthetic polymers can be made according to demand with more control over their structure and properties. Physical, chemical properties of natural and synthetic polymers have been discussed in this chapter. Polymers have also been used in textile processing including weaving and printing. This chapter highlighted some of such polymers as well.

References 1. Carraher, C.E., and Seymour, R.B., Seymour/Carraher’s polymer chemistry, Taylor & Francis, New York, USA, 2007.

58  Frontiers of Textile Materials 2. Gowariker, V.R., Viswanathan, N.V., Sreedhar, J., Polymer Science, Wiley, New Delhi, India, 1990. 3. Billmeyer, F.W., Textbook of polymer science, Wiley, New Delhi, India, 2007. 4. Deopura, B.L., Alagirusamy, R., Joshi, M., Gupta, B., Polyesters and polyamides, Woodhead Publishing Limited, Cambridge, UK, 2008. 5. Ebewele, R.O., Polymer science and technology, CRC Press, New York, USA, 2000. 6. Odian, G., Principles of polymerization, John Wiley & Sons, New Jersey, USA, 2004. 7. Matyjaszewski, K. and Davis, T.P., Handbook of radical polymerization, Wiley Online Library, New York, USA, 2002. 8. Klemm, D., Philpp, B., Heinze, T., Heinze, U., Wagenknecht, W., Comprehensive cellulose chemistry Volume 1: Fundamentals and analytical methods, Wiley Weinheim, Germany, 1998. 9. Wakelyn, P.J., Bertoniere, N.R., French, A.D., Thibodeaux, D.P., Triplett, B.A., Rousselle, M.A., Cotton fiber chemistry and technology, CRC Press, New York, USA, 2006. 10. Cook, J.G., Handbook of textile fibers natural fibers, p. 240, Woodhead Publishing, Cambridge, UK, 1984. 11. Sun, R., Cereal straw as a resource for sustainable biomaterials and biofuels: Chemistry, extractives, lignins, hemicelluloses and cellulose, Elsevier, London, UK, 2010. 12. Organon, F., Fiber economics bureau, Inc, vol. 76, Arlington, Virginia, USA, 2005. 13. Franck, R.R., Bast and other plant fibers, CRC Press, Cambridge, UK, 2005. 14. Zhang, Z., Ortiz, O., Goyal, R., Kohn, J., Biodegradable polymers: Handbook of polymer applications in medicine and medical devices, pp. 303–35, Elsevier, London, UK, 2014. 15. Kokot, S. and Keratin, Encyclopedia of materials: Science and technology, K.H.J. Buschow (Eds.), pp. 4363–8, Elsevier, Oxford, UK, 2001. 16. Alberts, B., Bray, D., Hopkin, K., Johnson, A.D., Lewis, J., Raff, M. et al., Essential cell biology, Garland Science, Tylor & Francis group, New York, USA, 2013. 17. Simpson, W.S. and Crawshaw, G., Wool: Science and technology, Woodhead Publishing Limited, Cambridge, UK, 2002. 18. Sohn, S., Strey, H.H., Gido, S.P., Phase behavior and hydration of silk fibroin. Biomacromolecules, 5, 3, 751–7, 2004. 19. Hakimi, O., Knight, D.P., Vollrath, F., Vadgama, P., Spider and mulberry silkworm silks as compatible biomaterials. Compos. Part B Eng., 38, 3, 324–37, 2007. 20. Manoukian, O.S., Sardashti, N. et al., Biomaterials for tissue engineering and regenerative medicine, in: Encyclopedia of Biomedical Engineering, R. Narayan (Ed.), pp. 462–82, Elsevier, Oxford, UK, 2019.

Polymers for Textile Production  59 21. Kozłowski, R.M. (Ed.), Handbook of Natural Fibers: Processing and Applications, Woodhead Publishing, New Delhi, India, 2012. 22. Ugbolue, S.C.O., Polyolefin Fibers: Structure, properties and industrial applications, Elsevier, Cambridge, UK, 2017. 23. Mishra, S.P. A text book of fiber science and technology, New Age International, New Delhi, 2000. 24. Titow, M.V., PVC technology, Elsevier, London, UK, 2012. 25. Plunkett R.J., The History of Polytetrafluoroethylene: Discovery and Development, In: High Performance Polymers: Their Origin and Development, Seymour R.B., Kirshenbaum G.S. (Eds.) pp. 261–266, Springer, Dordrecht, Germany, 1986. 26. Lewin, M., Handbook of Fiber Chemistry, CRC Press, Florida, USA, 2006. 27. Meredith, R., Elastomeric Fibers, Woodhead Publishing Limited, Cambridge, UK, 2004. 28. Karger-Kocsis, J. (Ed.), Polypropylene: An A-Z Reference, Springer, Amestradam, The Netherlands, 1999. 29. Pioneer Reports, Global Aramid Fiber Market Research Report 2012–2024, Pioneer Reports, 2019. 30. Cesare, A., Fabrizio, F., Reference books of textile technology: Man-made fibers, Fondazione Acimit, Milan, Italy, 2006. 31. Senthilkumar, M., Anbumani, N., Hayavadana, J., Elastane fabrics – A tool for stretch applications in sports. Indian J. of Fiber Text. Res., 36, 5, 300–7, 2011. 32. Gaaz, T.S., Sulong, A.B., Akhtar, M.N., Kadhum, A.A.H., Mohamad, A.B., Al-Amiery, A.A., Properties and applications of polyvinyl alcohol, halloysite nanotubes and their nanocomposites. Molecules, 20, 12, 22833–47, 2015. 33. Carvalho, A.J.F., Starch: Major sources, properties and applications as thermoplastic materials, in: Monomers, Polymers and Composites from Renewable Resources, N.B. Mohamed and G. Alessandro (Eds.), pp. 321–42, Elsevier, London, UK, 2008. 34. Nasrollahzadeh, M., Sajadi, S.M. et al., Applications of nanotechnology in daily life, in: An Introduction to Green Nanotechnology, M. Nasrollahzadeh (Eds.), pp. 113–43, Elsevier, Cambridge, USA, 2019. 35. Whistler, R.L., BeMiller, J.N., Paschall, E.F. (Eds.), Starch: Chemistry and technology, Academic Press, New York, USA, 2012. 36. Loureiro dos Santos, L.A., Natural polymeric biomaterials: Processing and properties. Reference Module in Materials Science and Materials Engineering, Elsevier, Amestradam, The Netherlands, 2017.

3 Advances in Polymer Coating for Functional Finishing of Textiles Asma Bouasria1,2, Ayoub Nadi1, Aicha Boukhriss1, Hassan Hannache2,3, Omar Cherkaoui1 and Said Gmouh2* Laboratory REMTEX, School of Textile and Clothing Industraies, Oulfa, Casablanca, Morocco 2 Laboratory LIMAT, Faculty of Sciences Ben M’sik Hassan II University of Casablanca, Casablanca, Morocco 3 Materials Science and Nanoengineering Department, Mohamed VI Polytechnic University, Benguerir, Morocco 1

Abstract

The functionalization of textiles is an emerging tool to improve textile performance and increase its added value. Several techniques can be used to impart new functionalities and properties to textile materials, including electrospinning, enzymatic treatments, plasma processing, nanotechnology, sol–gel and polymer coating. Advances in polymer and textile technology have led to phenomenal growth in the application of coated fabrics for many end-uses. Coated fabrics have an important place among technical textiles and constitute one of the most important technological processes of textile industry. This chapter reviews the different methods used to make coated fabrics such as polymer dip coating and melt coating, etc. Then, it describes the processing equipments, the physic-chemical nature of the polymer materials and the charges, as well as the most important functionalities provided by these techniques. Finally, the applications used for each method and the future trends in the field are reported. Keywords:  Functionalization of textiles, polymer coating, technical textiles

*Corresponding author: [email protected] Mohd Shabbir, Shakeel Ahmed, and Javed N. Sheikh (eds.) Frontiers of Textile Materials: Polymers, Nanomaterials, Enzymes, and Advanced Modification Techniques, (61–86) © 2020 Scrivener Publishing LLC

61

62  Frontiers of Textile Materials

3.1 Introduction Coating is a key functionalization technique to produce technical textile with added value properties. The challenge is to generate advanced function and to enhance the physic-chemical and biological properties of textile without modifying their intrinsic properties [1]. Coated textiles occupy a very important and specific place due to their various and interesting applications [2]. The areas where coated fabrics are used include Agriculture, Construction, Geotextiles, functional clothing, and technical components...etc. The term “functional coatings” describes systems which possess, besides the classical properties of a coating (i.e., decoration and protection), an additional functionality [3]. These additional functionalities are diverse, and depend upon the actual application of coated fabrics which are considered as technical fabrics that grants us technical proprieties. Typical examples of functional coatings are: chemical resistance, electrical conduction, bacteriostatic (or antibacterial) [4, 5], Antimicrobial [6, 7], waterproof [8], fireproof [9, 10], and abrasion resistant. Besides their added value properties, functional coatings must satisfy additional requirement including durability, reproducibility, easy application and cost effectiveness, tailored surface morphology, and environmental friendliness. Up to now, several coating technologies have been investigated to functionalize textile substrates for large scale applications and industrial production. Common textile coating processes include electroless plating [11], evaporative and plasma deposition, spray and dip coating, sputtering [12], and polymer coating. Polymer coating is one of the most used approaches to modify textile surfaces in order to obtain more comfortable properties and change its appearance and its physical characteristics [13]. The process consists to deposit the emulsified or dispersed polymer resins on the textile substrates and then fixe it by polymerization (cross-linking by hot air or infrared radiation) or by catalysis [14, 15]. A wide range of polymer coating processes are used and discussed in this chapter, depending on the targeted properties, starting with Knife Coating: also known as Direct Coating, back licking roller coating, Dip coating, and Foam Finishing Coating. But these techniques often presents intrinsic limitations [16], mainly because of the modification of the typical properties of the fabrics—i.e., flexibility, breathability, wettability, roughness—thus drastically limiting their use in common applications. Hence, the implementation of innovative technologies able to control the coating properties is a relevant challenge for textile applications.

Polymer Coating for Finishing of Textiles  63 This book chapter explores the various techniques used for polymer coating, ranging from the traditional approaches (Knife Coating, back licking roller coating, Dip coating and Foam Finishing Coating) to novel and emergent ones (plasma polymer coating, electrofluidodynamic and supercritical carbon dioxide processes). Also, different examples of functionalization via polymer coating are mentioned in this chapter.

3.2 Polymer Coating Methods Polymer coating is a method of depositing one or more layers of polymers on the surface of a textile substrate. Several coating techniques are used depending on the properties aimed for the final product. All of these techniques are aimed at having a good coated substrate with the desired properties and their application is done following three steps: “dose, transfer, and fix.” The dosage serves to control the quantity of polymers applied to the fabric. Transfer consists on depositing the coating material on the textile substrate and finally, the fixation serves to fix the transferred materials on the fabric. The choice of coating technique for textile material finishing depends upon the requirement of end product. Some of these processes are described below.

3.2.1 Dip Coating Dip coating is the easiest method of immersing the fabric in a bath containing the low viscosity coating polymer. As illustrated in Figure 3.1, the thickness of the layer is controlled using the forces balance applied to the Uncoated substrate

Forward two-roll

Dip coating

Coated substrate (not dried)

Nip

Figure 3.1  Dip coating and forces applied to the substrate during shrinkage (reprinted from Åkerfeldt, M [17]).

64  Frontiers of Textile Materials Coated release paper Release paper

Coating Fabric

Coated fabric

Heat and pressure

Figure 3.2  Transfer coating (reprinted from E. Shim et al. [18] with permission of Elsevier Publications).

substrate at the outlet of the bath. At the end of the process the fabric is dried at the appropriate temperature [17].

3.2.2 Transfer Coating Here, the coating is made on a non-stick silicone paper and then dried. Then, the coated paper and the substrate passes through the rollers by making the coated layer facing the surface of the substrate, the pressure applied by the rollers and the furnaces cause a bond between the substrate and the coated surface as illustrated in Figure 3.2, then the release paper is taken off leaving a smooth surface [18].

3.2.3 Kiss Roll Coating A roll is used to arrange the coating materials on the surface of the substrate. As illustrated in Figure 3.3, the lower half of the roll is immersed in a bath containing the coating polymer, during the rotation of the roll; the polymer is transferred to the surface of the substrate, which is in contact with the upper half of the roll [19].

3.2.4 Gravure Roll Coating In this technique, an engraved roll is immersed in a bath containing the coating polymer, and during rotation the coating material fills the etched

Polymer Coating for Finishing of Textiles  65 Fabric let off

Fabric take up

Fabric face

Solution

Figure 3.3  Kiss roll coating (reprinted from A.K. Patra et al. 2015 [19] with permission of Elsevier Publications).

Ink Doctor blade Gravure cylinder

Substrate

Figure 3.4  Gravure roll coating (reprinted from Vivek Subramanian et al. [20]).

pattern and the excess of the material forms a thin film on the surface of the roll. As illustrated in Figure 3.4, the film is removed using a squeegee which is then pressed on the substrate to transfer the coating polymer [20].

3.2.5 Slot Die or Extrusion Coating As illustrated in Figure 3.5, the extrusion coating consists of pressing a plasticized compound through a die sheet, which is spread directly on the substrate to be coated. The die lip is in direct contact with the surface of the substrate and supported by a cylinder that exerts pressure on the fabric [2].

3.2.6 Powder Coating In this technique, as illustrated in Figure 3.6, the powder is prepared in solid form and then deposited directly on the surface of the substrate. This technique is less polluted because it does not require solvents, and releases only a few volatile organic compounds [21].

66  Frontiers of Textile Materials

Slot die

Coating layer

Substrate

Figure 3.5  Slot die coating (reprinted from E. Shim et al. [2] with permission of Elsevier Publications). Coating powder

Substrate

Figure 3.6  Powder coating (reprinted from E. Shim et al. [21] with permission of Elsevier Publications).

3.2.7 Knife Coating This method of coating is used to cover a large surface with high speed, and consists of putting the polymer coating on the substrate in front of the knife; the movement of the latter ensures the deposition of the polymer on the surface of the substrate. The thickness of the polymer layer is related to the space between the knife and the fabric [14].

Polymer Coating for Finishing of Textiles  67 From all of the aforementioned techniques, knife coating technique has become one of the most used textile functionalization methods, due to its low cost, the variety and availability of the polymers used, as well as the permanence of the properties that it can confer to the substrate.

3.2.7.1 Choice of the Thickness This technique allows the formation of a film with a well-defined thickness. The final thickness of the film varies according to the surface energy of the substrate, and the viscosity of the coating polymers [22]. The final dry thickness can be calculated by the following empirical relation:

1 c  d= g  2 ρ



where: g: the distance between the knife and the substrate in cm;   c: concentration of the coating polymer in g/cm3;   ρ: the density of the coating material on the substrate in g/cm3; The thickness is determined according to the following criteria: - Distance between the knife and the fabric. - Type of fabric. - Type of the knife. - Angle of the knife. - Position of the knife.

3.2.7.2 The Viscosity Before adding the polymer, the fabric should be kept flat and under appropriate tension. The added weight depends on the tension applied to the length and the width of the fabric. Also, in order to have a good coating, it is important to adjust the viscosity of the resin. The viscosity changes as function of temperature and the amount of solvents or water. If low viscosity of polymer is used, it will flow easily and cause low tear strength of fabric. While a high viscosity will cause reduced water resistance and irregular coating of fabric [23].

3.2.7.3 Drying The last step in the direct method is drying. It is important to adjust the temperature to ensure the complete evaporation of solvents or water. The

68  Frontiers of Textile Materials first chamber of the furnaces must be set at a lower temperature to evaporate the solvent. The high temperature of the second chamber must be sufficient for polymers cross linking to the surface of the fabrics. Generally, the temperature depends on the nature of the used solvents. Fast drying can cause air bubbles and poor results.

3.2.7.4 Type of Knife Different types of knives are used in polymer coating processes. To choose the appropriate one, the knowledge of the layer thickness to apply, the configuration of the knife, and the viscosity of the paste are necessary. The type of blade controls the rate of addition of the resin; generally there are four types of blades as illustrated in Figures 3.7 and 3.8: ➢➢ A sharp blade: for weak addition of resin (a) ➢➢ A rounded blade: Produces a higher resin addition (b) ➢➢ A hoof blade: the bigger the shoe, the more important is the addition (c) ➢➢ A hoof blade inclined forward: it is close to a sharp blade (d)

Figure 3.7  Different angle positions of the blade (reprinted from M. Joshi et al. [25] with permission of Elsevier Publications).

(a)

(b)

(c)

(d)

Figure 3.8  Examples of blade profiles (schematic) (reprinted from M. Joshi et al. [25] with permission of Elsevier Publications).

Polymer Coating for Finishing of Textiles  69

3.2.7.5 Knife Use Technologies Here, we cite two technologies of use of knives for polymer application on textile surface: Jet air knife and knife over roll. a. K  nife coating process This method involves spreading the polymers on the fabric using a knife installed above the substrate. As illustrated in Figure 3.9, the thickness is controlled by a metering blade. In the end, the fabric goes into an oven for drying and fixing the coated layer [17]. b. Air jet knife As illustrated in Figure 3.10, this technique use the air steam jet for the application of the polymer on the substrate surface by the use of an air blowing blade (Air jet knife) [24]. Coating formulation

Coating knife/ blade

Coated textile Moving roller Moving textile substrate

Figure 3.9  Knife over roll coating (reprinted from Åkerfeldt, M [17]).

Air knife Coating material Air stream

Figure 3.10  Air knife coating knife over roll coating (reprinted from Meirowitz, R.E. [24] with permission of Elsevier Publications).

70  Frontiers of Textile Materials

3.2.7.6 Type of Knife Coating There are three types of knife coating techniques: knife in the air, knife on a blanket, and knife on roll. a. K  nife over the air The knife is placed behind a support and installed directly on the fabric. As illustrated in Figure 3.11. This technique is important for the application of impermeable coatings [25]. b. Knife on a blanket The band is supported by a short rubber cover between two rollers. As illustrated in Figure 3.12. The tension applied on the cover gives a pressure between the knife and the fabric. The amount of coating depends on the coverage tension, which is adjusted by the rollers [25].

Coating compound

Coating knife

+

Support channel

Support roll

Figure 3.11  Floating knife or knife over air (reprinted from M. Joshi et al. [25] with permission of Elsevier Publications).

Coating compound

Endless rubber blanket

Coating knife

Driver roll

Figure 3.12  Knife over blanket (reprinted from M. Joshi et al. [25] with permission of Elsevier Publications).

Polymer Coating for Finishing of Textiles  71 Knife coating Ink holder

Blade

Substrate

Figure 3.13  Knife over roll (reprinted from B. Roth et al. [22] with permission of Elsevier Publications).

c. K  nife on roll This is the most used method due to its accuracy and simplicity. As illustrated in Figure 3.13, this technique uses a squeegee well positioned on a roll. The roll can be made of steel coated with rubber or chromed [22].

3.3 New Technologies in Polymer Coatings 3.3.1 Plasma Treatment Technology The new plasma technology is a technique based on the application of a coating by the effect of a partially ionized gas composed of electrons, ions, photons, atoms, and molecules, with negative overall electric charge. As illustrated in Figure 3.14, the plasma process is a very reactive material, it

plasma source precursor

plasma

textile substrate

Figure 3.14  Principle of plasma processing (reprinted from Joshi, A. S. et al. [26]).

72  Frontiers of Textile Materials can be used to modify the surface of a some textile substrates to give it new functionalities, in recent years, the functionalization of textile by plasma treatment has experienced a remarkable development and revealed that as a new technology for textile processing, it has a huge potential in terms of cost reduction, water saving and eco-friendliness [26].

3.3.2 Electrofluidodynamic Treatment Technology The implementation of new methods of textile coating has become very important. As illustrated in Figure 3.15, new unconventional technology (electrofluidodynamic (EFD)) has been adopted to modify and cover textile surfaces by polymer (bioderived polymer:polylactid acid (PLA)) [27]. Electrofluidodynamic (EFD) is revolutionizing the traditional methods of functionalization of biomaterials by adopting a new technique, which consists of the use of electrostatic forces as a driving force for the fabrication of 3D models capable of addressing cells and/or molecules [28].

CONVENTIONAL EFDs

NON-CONVENTIONAL EFDs

ELECTROSPRAYING

ELECTROSPINNING

VOLTAGE

FEED RATE

PARTICLES

FIBERS

THIN FILM

40 µm 400 µm 20 µm

5 µm 100 µm

Figure 3.15  Scheme of different coating strategies for textile substrates by EFD processes (reprinted from F. De Falco et al. [27] with permission of Elsevier Publications).

Polymer Coating for Finishing of Textiles  73 H2 C

CH3

H2 C

C C

O n

CH3 C C

O

m

O

O CH2

CH2

CH2

CH2

CH2

OH

CH2 F3C

CF3 CF2 CF2 CF2

Figure 3.16  Scheme of textile substrate functionalized by supercritical carbon dioxide method (reprinted from Kazaryan, P. S. et al. [29] with permission of Elsevier Publications).

3.3.3 Supercritical Carbon Dioxide-Based Method Technology The supercritical carbon dioxide technology consists of simultaneous deposition of copolymers previously synthesized by radical polymerization in supercritical carbon dioxide in the presence of azobis–isobutyronitrile as an initiator, in addition to the crosslinking agents based on diisocyanate from supercritical carbon dioxide solutions; this deposition leads to getting a uniform coating. As illustrated in Figure 3.16, this technique allows to ensure a high hydrophobicity with very high angles of contact with water [29, 30].

3.4 Coating Materials The most commonly used coating materials in the knife coating technique are polymers or a mixture of polymers and various additives. Frequently used polymers include, silicone rubbers, polyvinyl chloride (PVC), polyethylene terephthalate (PET), polyurethane (PU), and polyacrylate (PA) and other elastomers [31]. The additives, which complete the composition of the coating resins can be softeners, preserving agents, hydrophobic agents [32, 33] humidity, pH, etc., fillers, thickeners, fixatives, pigments, flame retardants [34].

74  Frontiers of Textile Materials Polymers are used for smooth continuous yarn fabrics such as nylon, polyester, and cotton. The quantity of polymers applied is influenced by: ➢➢ The concentration of the solution ➢➢ The profile of the blade and its angle ➢➢ The tension and speed of the fabric

3.4.1 Polyvinylchloride (PVC) PVC is a white resin, insoluble in water. It is used to protect the pipes and also for textile coating. Figure 3.17 illustrates de polymerization of vinyl chloride to produce poly (vinyl chloride) polymer. PVC has an amorphous structure, it has no exact melting point, and it undergoes a change of properties between 170°C and 180°C. The polyvinyl chloride components are formulated by plasticizers in order to have flexible properties.

3.4.2 Polyacrylics (PA) Acrylic polymers are widely used in upholstery because of their wide range of properties. Coating formulations incorporating acrylic polymers provide good water resistance and do not age prematurely in intense sunlight. The Acrylic polymers are obtained by polymerization of acrylic esters and methacrylic acid (Their formula is given in Figure 3.18). They are prepared by mass polymerization, emulsion and solution. Emulsion polymerization is the preferred method for coating [35]. H

H

H

H

H

H

H

H

H

H

C

C

C

C

C

C

C

C

C

C

H

Cl

H

Cl

H

Cl H

Cl

H

Cl

H

H

H

H

H

H

C

C

C

C

C

C

H

Cl H

Cl H

Cl

vinyl chloride monomers

poly(vinyl chloride)

Figure 3.17  Schematic diagram of polymerization of vinyl chloride to produce PVC polymer.

Polymer Coating for Finishing of Textiles  75 H H2C

C

COOR

H2C

Acrylic acid or ester

C

H2C

COOR

Methacrylic acid or ester

H H2C

CN

CH3

C

COOR

Cyanoacrylic acid or ester

CN H2C

CN

C

Acrylonitrile

C

R = H Acid R = CH3 Methyl ester R = C2H5 Ethyl ester

CONH2

Acrylamide

Figure 3.18  Structural formula of acrylic monomers (reprinted from Sastri, V. R. et al. [35] with permission of Elsevier Publications).

3.4.3 Polyurethane (PU) Polyurethanes are produced by the polyaddition reaction between polyisocyanates and polyols (Their reaction is given in Figure 3.19). The used isocyanates in PU synthesis can be: • • • • •

Toluene diisocyanate Hexamethylene diisocyanate Diphenyl methane diisocyanate Xylene diisocyanate Ρ-phenylenediisocyanate.

The two types of polyols used are: • Polyester polyols and Polyether polyols

O

C

N

R

N

C

C

N

O

H

Figure 3.19  Structural formula of urethane.

O

R

OH

N

C

H

O

R'

O

OH

R'

O n

76  Frontiers of Textile Materials Table 3.1  Different polymers for textile coating. Polymers

Properties/advantages

Application

Polyurethane PU

- Solvent and latex form - Good extensibility - Good weathering and abrasion resistance - Films available for lamination

- Water proof protective clothing - Aircraft life jackets - Binders for nonwoven and glass fibers

Polyvinylchloride PVC

- Plastisols and waterbased available, which can be compounded to give wide range of properties - Good inherent FR, which can be improved - Good oil, solvent, and abrasion resistance

- Architectural uses - PVC polyester-tent covers - Leather - Tarpaulins

Polyvinylidene chloride PVDC

- Very good Fire Retardancy (FR) (blendable with PVC and acrylic latex) - Very low gas permeability

- Blends with acrylics to improve FR in coatings, e.g., coating on drinks bottles and coating roller blinds (film as shrink-wrap)

Poly(acrylics) PA

- Large number of variants and co-polymers - Wide range of properties - Blendable with other lattices - Good UV resistance and optical clarity, generally inexpensive

- Used as lacquers for tarpaulins - Backing for carpets and upholstery - Wall coverings, exhibition board backing

Polyolefin

- High resistance to acids, chemicals and alkalis - Low density - Less expensive than other polymers

- Used for bulk bags and tarpaulins as a substitute for PVC

Polymer Coating for Finishing of Textiles  77 The advantages of the use of polyurethanes in the coating are numerous, for instance: ➢➢ ➢➢ ➢➢ ➢➢

Good abrasion resistance Flexibility in a low temperature Good elongation They can give several properties to the substrates.

Table 3.1 summarizes the most used polymer for knife coating.

3.5 New Functionalities of Polymer Coatings Needs of the human being have totally changed and gone beyond traditional applications of polymer coating. Therefore, Research is under way to meet these needs and has brought new functions to textile surfaces such as flame retardant coatings, conductive coating, fluorescent and antibacterial coatings, etc. Some of them are discussed below.

3.5.1 Application in Smart Textile Smart textiles as type of technical textiles are a result of adding new functionalities to the surface of traditional textile. Furthermore, they are able to detect and react to changes in their environment such as thermal, chemical and mechanical changes. For instance, smart clothes can release medication or moisturizer onto the skin, assist regulate the muscular, vibrations during athletic activities, and even release materials able to control body temperature [36]. Recently, Song Chen et al. [37] have developed a multifunctional electronic textile based on fibers, as shown in Figure 3.20, knitted with hierarchical polyurethane (PU) fibers, by coating silver nanowires (AgNW) and styrene–butadiene–styrene polymer. Due to the AgNW conductive networks, the elaborate e-textile has conductivity, extensibility, high sensitivity and multi-detection of stress and pressure. Multifunction fabricated e-textiles are also successfully integrated into the electronic fabric for 2D strength mapping.

3.5.2 Flame Retardant Flame-retardant finishes provide a good fire performance for both natural and chemical fibers. The flame-retardant treatment is developed specifically for cellulose [9], cotton [38, 39], wool, and synthetic fibers.

78  Frontiers of Textile Materials (a) Coated with AgNWs

Coated with SBS

Fiber-shaped textile

Textile-AgNWs

(b)

(c)

Weaved into fabric E-fabric

E-textile (e)

140% strain (d)

2 cm (g)

(f)

1 mm

(h)

100 µm

(i)

0.5 µm

0.5 µm

Figure 3.20  Fabrication of the e-textiles and e-fabric (reprinted from Song Chen et al. [37]).

Several studies have been carried out on the flame retardant treatment of textile by different polymer coating techniques to confer fire resistance to the fabric [40–42]. The recent developments in flame retardancy of textile by polymer coating use chemical Flame retardants (FRs) based on Phosphor, Ammonium salt, Boron-nitrogen that are added to combustible textile material to increase its burning behavior [43]. For example: Feng Xiu Zhang et al. [41] have synthesized flame retardant material (FR) at low temperature for a flammable cotton fabric by a halogen-free and formaldehyde-free ammonium salt of melamine hexa(methylphosphonic acid) (AMHMPA). The percentages of carbonization residues of treated cotton fabrics and untreated fabrics were respectively 38.5% and 3.6% at 600°C. AMHMPA treated cotton has not cytotoxicity to the environment and humans. As shown in Figure 3.21, the results of this study showed that AMHMPA-treated cotton has ecological properties, exceptional permanence, and excellent flame-retardant behavior. Shubha et al. [44] synthesized a polymeric film formed on the cotton surface of the 2-methacryloyloxyethyl phosphorylcholine monomer by copolymerization using an azobis-isobutyronitrile initiator by admicellar polymerization at Using anionic surfactant (sodium dodecylbenzenesulfonic acid salt), with NaCl as an electrolyte. The thermal behavior in a nitrogen atmosphere was studied, which showed that the initial temperature of thermal degradation of the treated sample

Polymer Coating for Finishing of Textiles  79

HRR [kW/m2]

225 200 175 150 125 100 75 50 25 0 –25

0

205.95 [kW/m2]

AMHMPA treating cotton Control cotton

20.93[kW/m2]

50 100 150 200 250 300 350 400 450

O O P O Cellulose O P O Cellulose O N Cellulose N N O O Cellulose O Cellulose O P N N N P O O O O Cellulose Cellulose P AMHMPA P O Cellulose O O O Cellulose Cellulose

t[s]

Highly effective, durable and eco-friendly AMHMPA flame-retardant cotton

Figure 3.21  Water-solvent synthesis of AMHMPA by two steps and the preparation of AMHMPA-flame retardant cotton (Reprinted from F. Zhang et al. [41] with permission of Elsevier Publications).

decreases by 37°C with an increase of the coal yield of 21.7% at 600°C. The raw sample of cotton fabric burns the entire length of the 15 cm in 11.8 s, while the treated cotton fabric automatically turns off in an automatic flammability test.

3.5.3 Water Repellence Impermeability refers to the ability to prevent the ingress of water from outside. Total impermeability is guaranteed only by laminated membranes or a coating that forms a waterproof barrier to rain or snow. In these cases, the seams and zippers are also sealed. On the other hand, we must also take into account the breathability of fabric, especially during sports activities or during work-related efforts [8, 45]. The waterproof layer of fabrics is a very important function for clothes. But the washing with detergents reduces the waterproof function of clothes, as this effect will be lost through abrasion, leaching or contamination. Silicone or fluorocarbon can be used on the surface of clothes that have lost their water repellent effect, when these products are properly applied the water flows to the surface of the fabrics without sticking or wetting [46, 47]. For example Chao-Hua Xue et al. [48], have synthesized cotton samples by the padding method, working with polyacrylates and polyphosphate ammonium. Coated fabrics exhibit superhydrophobia with a self-cleaning effect, and also exhibit a flame retardancy property. Chao-Hua Xue et al. [49] have developed a superhydrophobic fabrics by functionalizing fibers with polyhederic POSS-based polymers as shown in Figure 3.22, the prepared superhydrophobic fabrics showed a high stability with the acid, base, salt, acetone, and N, N-dimethylformamide.

80  Frontiers of Textile Materials Fabric-SH

Pristine fabric

Fabric-S-OVPOSS

vapor deposition

UV irradiation

MPTES

OH

O O Si O

OH

OVPOSS,PETMP

SH

SH

SH

OH

SH SH

SH

SH

S

SH HS

S SH SH

S

S

S S

SH SH SH

OVPOSS,

SH HS

O

SH SH

PETMP,

HS HS

O O O O O O O

SH SH

S

S

n

S

n

N

O Si O Si Si OO Si OO N O Si ONSi O O Si O Si O N

SH SH

N

N

MPTES,

SH

N

N

O O Si O

n

S

S

n

POSS-based polymer

Figure 3.22  Schematic illustration of the fabrication of superhydrophobic fabrics (Reprinted from Chao-Hua Xue et al. [49] with permission of Elsevier Publications).

Ronggang Cai et al. [50] have adopted an easy, and environmentally friendly method to develop superhydrophobic fabrics by a simple method of dip coating in suspensions and water-based emulsions. All materials used (PDMS and silica) are fluoride-free and widely available. The contact angle with the water measured on the coated samples was superior to 145°, as shown in Figure 3.23.

Water-based emulsion/suspension Low surface tension: PDMS

PES fabric

Provide roughness: Silica particles Anchoring layer: PDMS

Figure 3.23  Sketch of the preparation of superhydrophobic PES fabrics including the deposition on bare fabrics (Reprinted from Ronggang Cai et al. [50]).

Polymer Coating for Finishing of Textiles  81

3.5.4 Antibacterial Function In order to limit the adhesion of bacteria to the textile substrates, it is necessary to add a function against microorganisms provided by an active agent [51]. These active ingredients have the role of reducing the growth of bacteria and reduce their side effects [5, 52]. An antibacterial treatment consists in dispersing the active agents and putting them in solution to apply it either by impregnation or by the direct method [4]. For example Ying Zhan Li et al. [53] have developed permanent flame retardant and antibacterial hybrid coated fabrics for cotton fabrics by simultaneous dopamine polymerization and hydrolytic condensation of N3P3 [NH (CH2)3Si (OC2H5)3]6. Silver nanoparticles have also been introduced CH =CH2 CH3

CH2 N n

CH3 CH3

Quaternization + Cl CH2 CH=CH2

CH2

CH3 N + Cl – CH3 CH2 n

Step a

CH3

n=11,13,15,17

Antibacterial monomers

CH3 CH3

CH3 CH3 CH3 CH=CH2 + CH2=C + CH=CH2 + CH2=CH + CH2=C + CH2=C + CH2=CH + CH2=CH C=O C=O C=O C=O C=O CH2 O O Si OH O NH + – CH CH 2 2 N Cl CH2 3 OOO CH2 CF2 5 CH 2 CH 3 CH2 n OH H3C CH3 CH3 OH CHF2 CH3

Seed emulsion polymerization

Step b

CH3 CH3

CH3 CH=CH2 CH2=C CH2 CH CH2 CH CH2 C=O C=O CH2 O O + – CH2 N Cl CH2 CF2 5 CH3 CH2 11 CHF2 CH3

CH3 C CH2 C=O O CH2 CH2 OH

CH3 C CH2 CH CH2 CH n C=O C=O Si OH NH O OO CH2 OH H3C CH CH3 3

Step c Spray coating

Antibacterial and bacterially anti-adhesive fabic

Pristine cotton fabric

Antibacterial polymer emulsions

Figure 3.24  Schematic of the synthesis route for the antibacterial and bacterially antiadhesive cotton fabric. (Reprinted from Jing Lin et al. [54]).

82  Frontiers of Textile Materials into Coatings by reaction of AgNO3 with catechol fractions on polydopamine (PDA) in the absence of any external reducing agent. Considerable flame retardancy was obtained for treated cotton fabrics, which also exhibited antibacterial activity against Gram-positive S. aureus bacteria and Gram-negative E. coli bacteria. Functionalization was durable with flame retardant and antimicrobial properties largely intact after 30 wash cycles. Jing Lin et al. [54], have successfully synthesized a range of antibacterial and quaternary ammonium polymers to be copolymerized with fluorine-containing acrylic monomers and other monomers to yield cationic cotton fabrics and durably antibacterial and anti-adhesive properties. As shown in Figure 3.24, the study showed that the antibacterial activities of the coated fabrics are influenced by the length of the alkyl chain and the content of antibacterial monomers, as well as by the added polymer concentration.

3.6 Conclusions and Future Outlook This book chapter has clearly demonstrated the importance, feasibility and reliability of coating techniques as effective surface functionalization treatments for textiles. In fact, it is easy to adapt the coating formulations to obtain significant improvements as regards resistance to water penetration, fireproofing, antibacterial activity, etc. In addition, the coating application techniques are diverse and they are different from each other in term of technology, type of devices and end use product. From the scientific research carried out in recent years, it seems that further development and the optimization of these coating techniques could lead to strong development and industrial exploitation. Recent researches have demonstrated that coating combined with nanotechnologies using electrospinning techniques provide new surface properties. This technique is based on coating textile with nanofiber, which is responsible to bring them novel properties such is: breathability, antimicrobial activities, and hydrophobicity. Also, plasma, electrofluidynamic, electroless plating, and digital inkjet technologies will lead to a significant changes in textile thin layer coating especially to develop conductive fiber for wearable e-textile.

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84  Frontiers of Textile Materials 17. Åkerfeldt, M., Electrically conductive textile coatings with PEDOT: PSS, Engineering and Business University of Borås, Printed in Sweden by Ale Tryckteam, Bohus Sweden, 2015. 18. Shim, E., 10 - Bonding requirements in coating and laminating of textiles, in: Joining Textiles, vol. p, I. Jones and et G. K. Stylios (Eds.), pp. 309–351, Woodhead Publishing, UK, 2013. 19. Patra, A.K. and Pattanayak, A.K., 16 - Novel varieties of denim fabrics, in: Denim, vol. p, R. Paul (Ed.), pp. 483–506, Woodhead Publishing, Germany, 2015. 20. Subramanian, V. and Sung, D., Gravure as an Industrially Viable Process for Printed Electronics, EECS Department University of California, Berkeley, Technical Report No. UCB/EECS 2008-70 May 23, 2008. 21. Shim, E., 2 - Coating and laminating processes and techniques for textiles, in: Smart Textile Coatings and Laminates, Second Edition, W.C. Smith (Ed.), pp. 11–45, Woodhead Publishing, 2019. 22. Roth, B., Søndergaard, R.R., Krebs, F.C., Roll-to-roll printing and coating techniques for manufacturing large-area flexible organic electronics, in: Handbook of Flexible Organic Electronics, pp. 171–197, Elsevier, Greece, 2015. 23. Xanthos, M., POLYMER PROCESSING, in: Applied Polymer Science: 21st Century, C.D. and et C. E. CraverCarraher (Ed.), pp. 355–371, Pergamon, Oxford, 2000. 24. Meirowitz, R.E., 8 - Coating processes and techniques for smart textiles, in: Active Coatings for Smart Textiles, J. Hu (Ed.), pp. 159–177, Woodhead Publishing, Hong Kong, 2016. 25. Joshi, M. and Butola, B.S., 14 - Application technologies for coating, lamination and finishing of technical textiles, in: Advances in the Dyeing and Finishing of Technical Textiles, M.L. Gulrajani (Ed.), pp. 355–411, Woodhead Publishing, 2013. 26. Joshi, A.S., Sharma, U., Bais, S., Joshi, J., Prajapati, R., Kushwah, G., Prajapat, C., Application of Plasma finishing on Cotton Fabric. Int. J. Eng. Res. Appl., 5, 4, 01–10, April 2015. 27. De Falco, F., Design of functional textile coatings via non-conventional electrofluidodynamic processes. J. Colloid Interface Sci., 541, 367–375, Avr. 2019. 28. Cruz Maya, I. and Guarino, V., 1 - Introduction to electrofluidodynamic techniques. Part I: process optimization, in: Electrofluidodynamic Technologies (EFDTs) for Biomaterials and Medical Devices, V. Guarino and L. Ambrosio (Eds.), pp. 1–17, Woodhead Publishing, Italy, 2018. 29. Kazaryan, P.S., Tyutyunov, A.A., Kondratenko, M.S., Elmanovich, I.V., Stakhanov, A.I., Zefirov, V.V., Khokhlov, A.R., Superhydrophobic coatings on textiles based on novel poly(perfluoro-tert-hexylbutyl methacrylate-cohydroxyethyl methacrylate) copolymer deposited from solutions in supercritical carbon dioxide. J. Supercrit. FluidsMars, 149, 34–41, 2019. 30. Zefirov, V.V., Lubimtsev, N.A., Stakhanov, A.I., Elmanovich, I.V., Kondratenko, M.S., Lokshin, B.V., Khokhlov, A.R., Durable crosslinked

Polymer Coating for Finishing of Textiles  85 omniphobic coatings on textiles via supercritical carbon dioxide deposition. J. Supercrit. Fluids, 133, 30–37, 2018. 31. Akovali, G., 1 Thermoplastic Polymers Used in Textile Coatings, in: Advances in Polymer Coated Textiles, Akovali, G. (Ed.), p. 24. 32. Das, S., Kumar, S., Samal, S.K., Mohanty, S., Nayak, S.K., A Review on Superhydrophobic Polymer Nanocoatings: Recent Development and Applications. Ind. Eng. Chem. Res., 57, n 8, 2727–2745, 2018. 33. Das, A., Deka, J., Raidongia, K., Manna, U., Robust and Self-Healable BulkSuperhydrophobic Polymeric Coating. Chem. Mater., 29, n 20, 8720–8728, Oct. 2017. 34. Horrocks, A.R., Kandola, B.K., Davies, P.J., Zhang, S., Padbury, S.A., Developments in flame retardant textiles—A review. Polym. Degrad. Stab., 88, n 1, 3–12, avr. 2005. 35. Sastri, V.R., Chapter 7 - Engineering Thermoplastics: Acrylics, Polycarbonates, Polyurethanes, Polyacetals, Polyesters, and Polyamides, in: Plastics in Medical Devices, V.R. Sastri (Ed.), pp. 121–173, William Andrew Publishing, Boston, 2010. 36. Khattab, T.A., Rehan, M., Hamdy, Y., Shaheen, T.I., Facile Development of Photoluminescent Textile Fabric via Spray Coating of Eu(II)-Doped Strontium Aluminate. Ind. Eng. Chem. Res., 57, n 34, 11483–11492, Août 2018. 37. Chen, S., Liu, S., Wang, P., Haizhou, L., Liu, L., Highly stretchable fibershaped e-textiles for strain/pressure sensing, full-range human motions detection, health monitoring, and 2D force mapping. J. Mater. Sci., 53, Nov. 2999–3005, 2017. 38. Bentis, A., Boukhriss, A., Boyer, D., Gmouh, S., Development of flame retardant cotton fabric based on ionic liquids via sol–gel technique. IOP Conf. Ser. Mater. Sci. Eng., 254, 122001, Oct. 2017. 39. Bentis, A., Boukhriss, A., Grancaric, A.M., El Bouchti, M., El Achaby, M., Gmouh, S., Flammability and combustion behavior of cotton fabrics treated by the sol gel method using ionic liquids combined with different anions. Cellulose, 26, n 3, 2139–2153, Févr. 2019. 40. Chan, S.Y., Si, L., Lee, K.I., Ng, P.F., Chen, L., Yu, B., Hu, H., Yuen, Y., Xin, G.H., Fei, B., A novel boron–nitrogen intumescent flame retardant coating on cotton with improved washing durability. Cellulose, 25, n 1, 843–857, Janv. 2018. 41. Zhang, F., Gao, W., Jia, Y., Lu, Y., Zhang, G., A concise water-solvent synthesis of highly effective, durable, and eco-friendly flame-retardant coating on cotton fabrics. Carbohydr. Polym., 199, 256–265, Nov. 2018. 42. Zhu, F., Feng, Q., Xu, Y., Hu, J., Intumescent flame retardant coating for polyamide 6,6 (PA 6,6) fabrics containing carbon nanotubes: Synergistic effect of filler on thermal stability and flame retardancy. Text. Res. J., 89, n 10, 2031– 2040, Mai 2019. 43. Edwards, B., Rudolf, S., Hauser, P., El-Shafei, A., Preparation, Polymerization, and Performance Evaluation of Halogen-Free Radiation Curable Flame

86  Frontiers of Textile Materials Retardant Monomers for Cotton Substrates. Ind. Eng. Chem. Res., 54, 150109100032004, 2015. 44. Shubha, and Dahiya, J.B., Flame retardant coating on cotton fabric with phosphorus containing polymeric film by admicellar polymerization. IJFTR, 434, 457–463, Dec. 2018. 45. Ozen, I., Multi-layered Breathable Fabric Structures with Enhanced Water Resistance. J. Eng. Fibers Fabr., 7, n 4, 7, 2012. 46. Choi, B., Lee, J., Han, H., Woo, J., Park, K., Seo, J., Lee, T., Highly Conductive Fiber with Waterproof and Self-Cleaning Properties for Textile Electronics. ACS Appl. Mater. Interfaces, 10, n 42, 36094–36101, Oct. 2018. 47. Das, S., Kumar, S., Samal, S.K., Mohanty, S., Nayak, S.K., A Review on Superhydrophobic Polymer Nanocoatings: Recent Development and Applications. Ind. Eng. Chem. Res., 57, n 8, 2727–2745, Févr. 2018. 48. Xue, C.-H., Zhang, L., Wei, P., Jia, S.-T., Fabrication of superhydrophobic cotton textiles with flame retardancy. Cellulose, 23, n 2, 1471–1480, Avr. 2016. 49. Xue, C.-H., Fan, Q.-Q., Guo, X.-J., An, Q.-F., Jia, S.-T., Fabrication of superhydrophobic cotton fabrics by grafting of POSS-based polymers on fibers. Appl. Surf. Sci., 465, 241–248, Janv. 2019. 50. Cai, R., Glinel, K., De Smet, D., Vanneste, M., Mannu, N., Kartheuser, B., Nysten, B., Jonas, A.M., Environmentally Friendly Super-Water-Repellent Fabrics Prepared from Water-Based Suspensions. ACS Appl. Mater. Interfaces, 10, n 18, 15346–15351, Mai 2018. 51. Petkova, P., Francesko, A., Perelshtein, I., Gedanken, A., Tzanov, T., Simultaneous sonochemical-enzymatic coating of medical textiles with antibacterial ZnO nanoparticles. Ultrason. Sonochem., 29, 244–250, 2016. 52. Sharkawy, A., Fernandes, I.P., BAarreiro, M.F., Rodrigues, E., Shoeib, T., Aroma-Loaded Microcapsules with Antibacterial Activity for Eco-Friendly Textile Application: Synthesis, Characterization, Release, and Green Grafting. Ind. Eng. Chem. Res., 56, n 19, 5516–5526, Mai 2017. 53. Li, Y., Wang, B., Sui, X., Xie, R., Xu, H., Zhang, L., Zhong, Y., Mao, Z., Durable flame retardant and antibacterial finishing on cotton fabrics with cyclotriphosphazene/polydopamine/silver nanoparticles hybrid coatings. Appl. Surf. Sci., 435, 1337–1343, 2017. 54. Lin, J., Chen, X.Y., Chen, C.Y., Hu, J.T., Zhou, C.L., Cai, X.F., Wang, W., Zheng, C., Zhang, P.P., Cheng, J., Guo, Z.H., Liu, H., Durably Antibacterial and Bacterially Antiadhesive Cotton Fabrics Coated by Cationic Fluorinated Polymers. ACS Appl. Mater. Interfaces, 10, n 7, 6124–6136, 2018.

4 Functional Finishing of Textiles with β-Cyclodextrin Aminoddin Haji Department of Textile Engineering, Yazd University, Yazd, Iran

Abstract

Nowadays, there is a great interest in the textile industry for production of functio­ nal textiles using environmentally friendly materials and processes. Cyclodextrins are cyclic oligosaccharides with truncated cone shape having hydrophilic sur­ face containing hydroxyl groups and a cavity with hydrophobic character which is able to form reversible inclusion complexes with various compounds. Several derivatives of β-cyclodextrin have been synthesized to enable it to attach to textile fibers permanently. Also different methods have been developed for grafting of native and modified β-cyclodextrin on textile fibers. In this chapter the methods of application of β-cyclodextrin on different textile substrates for obtaining vari­ ous functional properties including antibacterial, anti-odor, dyeability, wastewater pollutant removal, drug delivery and fragrance release properties is reviewed. Keywords:  Cyclodextrin, medical textiles, antibacterial, functional properties

4.1 Introduction Due to the increasing demand for sustainable textiles, the use of sustain­ able chemicals in textile processing is recommended. In this way, cyclodex­ trins (CDs) and chitosan are examples of the most investigated materials for functionalization of textiles for different purposes. Cyclodextrins can be used for imparting various functional properties to textiles including antimicrobial and antifungal activity, UV protection, aroma finishing, Email: [email protected] Mohd Shabbir, Shakeel Ahmed, and Javed N. Sheikh (eds.) Frontiers of Textile Materials: Polymers, Nanomaterials, Enzymes, and Advanced Modification Techniques, (87–116) © 2020 Scrivener Publishing LLC

87

88  Frontiers of Textile Materials insecticide finishing, and dyeing improvement. They are biocompati­ ble, biodegradable, and consumer friendly as can be used in the food industry [1]. Cyclodextrins are cyclic oligosaccharides, produced by enzymatic deg­ radation of starch. There are three abundant types of cyclodextrins, namely, α-cyclodextrins, β-cyclodextrins, and γ-cyclodextrins, which are com­ prised of six, seven, and eight glucose units, respectively. The glucose units are linked by α-1,4-glycosidic bonds, and the covalent bonds are formed at carbon atoms C1 and C4 between the D-glucose units. The chemical struc­ tures of cyclodextrins are shown in Figure 4.1 [1, 2]. As shown in Figure 4.2, cyclodextrins are hollow, truncated-cone shaped molecules. Their cavity is hydrophobic and the outer layer is hydro­ philic, due to the special arrangement of the hydroxyl groups. The primary hydroxyl groups on carbons C6 are located on the narrow side (primary OH

OH OH

OH O

HO

OH

HO

α-CD OH HO O

HO

O

HO O

OH

OH

O

O

OH

O

OH O

HO HO

HO O

OH

O

O

O

O

OH O

HO O

HO OH

HO

OH

HO

O

HO

O

HO

OH O

OH

HO

γ-CD

OH

O

O HO

OH

HO

OH

O OH

OH

HO O

OH

O

HO

β-CD

OH

HO

OH O

HO

O

O

O O

HO

OH

HO

O

OH

OH

O

HO

HO

O

HO

O

HO

HO

OH

O

O

O

HO OH

O

O OH HO

O

O

O

OH

O O

HO

HO

Figure 4.1  Chemical structures of cyclodextrins.

OH O

HO

Hydrophobic cavity

O

OH OH

6

OHO HO

II

CH2OH

Secondary face

4

HO

Primary face

O OH

3

2

1

I OHO

O

VII

III

OH O OH

β-CD

OH O OH

OH

HO

HO

VI IV

O

 

O

5

HO

Figure 4.2  Representation of a β-cyclodextrin molecule [2].

OH V O OH O

OH OH O

OH

OH O

Functional Finishing of Textiles with β-Cyclodextrin  89 face) and the secondary hydroxyl groups on carbons C2 and C3 are located on the wider side (secondary face) [2–4]. Unlimited chemical modifica­ tions can be made on CDs due to the presence of these hydroxyl groups. The hydrophobic cavity of the cyclodextrins provides a microenvironment for entrapment of molecules with appropriate size (organic, inorganic, organometallic compounds) and enables them to form inclusion com­ plexes through a host–guest mechanism. The guest compounds may be neutral, cationic, anionic or even radical. CDs can host the guest molecules permanently or temporarily which may be favorable for certain applica­ tions. Cyclodextrins can form the host–guest inclusion complexes when they are in solution or solid form, and this can be done when they are con­ nected to another substrate as well [5, 6]. They can be attached to the sur­ face of various textile substrate and provide different functional properties. The outer layer of CDs is hydrophilic and which enables the CDs to dissolve in polar solvents such as water, alcohols, dimethyl formamide, dimethyl sulfoxide, etc. The solubility of β-cyclodextrins is lower than the other two major types.

4.2 Properties of Cyclodextrins Due to the simplicity of the production process, cheaper price, less irri­ tating, and skin-friendliness, β-cyclodextrin are more commonly used compared with the other types of CDs. The molecular weight of β-CD is 1135 g/mol. Its dimensions are as follows: height = 750–800 pm, external diameter = 1530 pm, and internal diameter = 600–680 pm. Due to the presence of the hydroxyl groups on the outside of the cyclodextrin mole­ cules, they are soluble in water, for example 1.85 g of β-CD can dissolve in 100 mL of water. Unmodified CDs are stable in alkaline media (up to pH values of 12.1) and unstable in acid conditions (pH lower than 3) [1, 6]. The most important and useful characteristic of CDs is their ability to host various solid, liquid and gaseous compounds and form solid inclusion complexes (“host–guest” complexes) with them. The occurrence of the inclusion complex depends on the dimensional fit between the host (CDs) and guest molecules. The hydrophobic forces are the most important driv­ ing force in this phenomenon and no covalent bonds are formed. However, other forces, such as van der Walls and dipole–dipole interactions, may be involved in the binding of the guest. Usually one guest molecule is com­ plexed in one CD molecule, unless in case of some low molecular weight molecules, which more than one guest molecule may include in the cavity. In case of high molecular weight molecules, more than one CD molecules

90  Frontiers of Textile Materials may form inclusion complex with one guest molecule [5, 7]. Generally, depending on the size of the guest molecules and conditions, 1:1, 1:2, 2:1, and 2:2 inclusion complexes can be formed. The interaction between the host and guest molecules is an equilibrium. Figure 4.3 shows the different types of inclusion complexes schematically [8]. Several methods can be employed for preparation of CD-guest inclusion complexes. The selection of the complex preparation depends on the type of the CD and nature of the guest molecules. Briefly, the most important methods for preparation of the cyclodextrin inclusion complexes include kneading (for poorly water-soluble guests), co-precipitation (for non-watersoluble guests), heating in a sealed container (for thermostable volatiles), freeze-drying or lyophilization (for thermolabile or water soluble guests), and spray drying (for thermostable molecules) [7]. Cyclodextrins are used in several applications including pharmaceuti­ cals, food and flavors, agricultural, textile, chemical, cosmetics, and toilet­ ries industries. Functional finishing of textiles using cyclodextrins is one of the emerging areas of cyclodextrins research [1].

CD

Guest

CD

Inclusion complex (1:1)

Guest

CD

CD

Inclusion complex (1:2)

Guest

Guest

Inclusion complex (2:1)

Inclusion complex (2:2)

Figure 4.3  Schematic representation of different types of inclusion complexes between CDs and guest molecules [8].

Functional Finishing of Textiles with β-Cyclodextrin  91

4.3 Chemical Modification of Cyclodextrins The solubility of natural cyclodextrins in common solvents is limited and the contain only one type of functional group, i.e., –OH, which restricts their application possibilities. To obtain cyclodextrins with new appli­ cations such as solubilizing agent, stabilizer, viscosity modifier, etc., and enhancing their binding behavior, different chemical modifications have been proposed and various CD derivatives have been synthesized. The most commonly industrially produced CD derivatives include methylated β-CD, heptakis(2,6-dimethyl)-β-CD, heptakis(2,3,6-trimethyl)-β-CD, hydroxypropyl-CD, peracetylated β-CD, sulfobutylether-CD, sulfated CD, etc. All these derivatives show higher water solubility than their parent native CD (>50 g/100 mL), and can be used for solubilizing of different compounds such as drugs [6]. CycloLab (Hungary) is the producer of various reactive cyclodextrins. halogenated/tosylated cyclodextrins, Azido-bearing CDs, amino CDs, and thiol CDs are examples of functional CDs manufactured by this com­ pany. Wacker-Chemie (Germany) offers products under the trade name CAVASOL®, which are either methylated or hydroxypropylated cyclodex­ trin derivatives and are more soluble in aqueous media than the native cyclodextrins. Their applications include (but not limited to) controlled release of pharmaceuticals, increasing the blood solubility and bioavail­ ability of drugs, textile fresheners, and auxiliary in polymerization. Monochlorotriazinyl-β-cyclodextrin (MCT-β-CD) is the a reactive cyclodextrin derivative which can form permanent covalent bonds with textile fibers (especially cellulosic fibers) through the conventional reactive dyeing method [9]. Figure 4.4 shows two different CD-derivatives which have been used for cellulose functionalization. Monochlorotriazinyl-β-CD (MCT-CD) (1) has been widely employed for modification of cotton to impart functionalities such as wrinkle proofing, wettability, dyeability, antiodor, and flame-retardant properties. Acrylamidomethyl-β-CD (2) has a vinyl group in the side chain which is able react with hydroxyl groups of cellulose, and attach the CD molecule to the cotton fibers [10–12].

4.4 Methods for Attachment of β-CD on Textiles Cyclodextrins have only hydroxyl groups as functional groups, so there is no strong chemical bonding between CDs and textile fibers in their native form. Several methods have been proposed for permanent fixation of CDs on textile fibers including the use of crosslinking agents, chemical

92  Frontiers of Textile Materials OR O RO

OR

(1) R=H or R= O

7

(2) R=H or R=

N N

ONa N CI O

N H

Figure 4.4  Chemical structures of monochlorotriazinyl-β-CD (1), and acrylamidomethyl-β-CD (2).

modification of CDs, modification of the textile substrate, etc. Selection of the best method for attachment of CDs to a textile substrate depends on different factors such as the end application and type of the fiber [13]. Several methods including crosslinking with different chemicals (epi­ chlorohydrin, polycarboxylic acids, DMDHEU), employing reactive derivatives of CD such as MCT-β-CD and N-methylolacrylamide-β-CD, grafting using glycidyl methacrylate, bifunctional reactive dyes, and butyl acrylate, as well as non-ionic and cationic derivatives of β-CD (for hydro­ phobic and acrylic fibers, respectively), enzymatic coupling and sol-gel process, have been studied for attachment of β-CD to various textile fibers [14–18]. A number of the convenient and frequently studied methods are briefly described in this chapter. Epichlorohydrin can form crosslinks between CD molecules and cellulose chains in the presence of caustic soda and attach the CDs to cotton fibers. The proposed mechanism of the reaction is shown in Figure 4.5 [19, 20]. Crosslinking agents like dimethylol dihydroxy ethylene urea (DMDHEU), citric acid (CA), and 1,2,3,4-butane tetra carboxylic acid (BTCA) can be used for permanent fixation of CDs on different textile fibers. Montazer and Jolaei compared the effect of crosslinking of β-CD on spacer polyester fabric using DMDHEU, CA, and BTCA. They found that BTCA was the most efficient crosslinking agent regarding the durability of CD of polyester fibers after 10 washing cycles. The β-CD-polyester fabric was dyeable with reactive dyes and absorbed chrome ions form water [21]. Kacem et al. grafted hydroxypropyl-β-cyclodextrin on woven polyester prostheses using citric acid by a pad-dry-cure process. The surfaces of the grafted fibers contain both carboxylic acid groups and β-CD molecules, which are able to interact with cationic compound through ionic bonding and inclusion-complexes. The finished prostheses were dyed with meth­ ylene blue and showed bactericidal effect [22]. Ducoroy et al. used citric acid, BTCA, and polyacrylic acid (by pad-dry-cure) for grafting of β-CD on PET nonwoven and obtained a filter nonwoven capable of removal of different heavy metal ions from water [23–25].

Functional Finishing of Textiles with β-Cyclodextrin  93 O OH

CD= Cyclodextrin, EP= Epichlorohydrin

CD

CH2

(EP) CH CH2Cl NaOH

OH CH2 CH

CD O

CH2Cl

O

NaOH

CD O

−HCI

CH2 CH

CH2

OH NaOH

CD O

EP

NaOH

CH2 CH

CH2 ONa

NaOH

−HCI OH

Cellulose

CD O CH2 CH

CH2 O

Cellulose n

Cellulose chain

CD

Figure 4.5  Mechanism of attachment of CD to cellulose using epichlorohydrin [19].

Crosslinking agents like CA and BTCA can covalently bond CD mol­ ecules to wool and cotton fibers. Due to the presence of hydroxyl groups in the polymeric structure of these fibers, esterification reaction is pos­ sible between carboxyl groups of the cross-linkers and the hydroxyl groups of the fiber. The hydroxyl groups of cyclodextrin can participate in the esterification reaction as well and attach the CD to the fiber [26, 27]. Figure 4.6 schematically presents the attachment of CD to wool using BTCA as crosslinking agent. More than one CD molecule can form ester linkage with one molecule of BTCA and CD molecules can form a cross-linked network on the textile fiber. Oxygen plasma treat­ ment of wool can produce new hydroxyl and carboxylic acid groups on

94  Frontiers of Textile Materials O NH O

R1 NH

R2

Wool

R1

O

BTCA SHP

NH

NH

O HO

O

NH

NH

R2

O

O

HO

O

OH

O O

CD

NH O

HO

R1

NH

NH O

R2

O

OH O

HO

HO

O

OH

O O-CH2

O CH2 O

O

O

HO

Figure 4.6  Schematic representation of Wool-BTCA-CD reaction [26].

the surface of the fibers and increase the grafting efficiency of β-CD on wool fibers [28]. Pad-dry-cure which is a conventional continuous method in textile fin­ ishing, is usually employed for grafting of cyclodextrin molecules to tex­ tiles. To attach cyclodextrin to cotton using polycarboxylic acids, a typical impregnation bath includes the desired amount of cyclodextrin, BTCA (or CA) and SHP [29, 30]. The concentration of these ingredients may differ for different intended applications. As an example, the fabric is padded with a wet pick-up of 100% and dried at 80–100°C. Curing is followed at 180°C for about 3 min [31, 32]. The esterification reaction between cotton cellulose or cyclodextrin with BTCA (or other polycarboxylic acids) includes two steps. In the first step, a cyclic anhydride forms between two adjacent carboxylic acid groups. In the second step, esterification reaction takes place between the previously formed acid anhydrides and the hydroxyl groups of the cellulose macromol­ ecules and cyclodextrin to form ester bonds. Some carboxylic acid groups may remain intact [31, 33–35]. The cross-linking mechanism of cellulose and cyclodextrin hydroxyl groups with BTCA is shown in Figure 4.7. Polycarboxylic acids can be used as crosslinking agents for attachment of cyclodextrins to polyester, polyamide, and polypropylene as well [32, 36–42]. For example, El-Ghoul et al. used citric acid to graft β-CD on knit­ ted PP fabric and improved the dyeability of the fabric with disperse, acid, and reactive dyes [43].

Functional Finishing of Textiles with β-Cyclodextrin  95 H2C-COOH HC-COOH

O H2C-C O HC-C O O HC-C O H2C-C O

SHP Heat

HC-COOH H2C-COOH BTCA

Cellulose Cyclodextrin

Curing

O H2C-COH2C HC-COOH HC-COOH H2C-CO O O

OH

OH

O OH

HO

Figure 4.7  Mechanism of crosslinking of CD to cotton in the presence of BTCA and SHP [31, 44, 45].

Dehabadi et al. synthesized a polyaminocarboxylic acid via carbox­ ylation of linear polyvinylamine a by bromoacetic acid, under alkaline conditions. The synthesized polyaminocarboxylic acid was used as a cross­ linking agent for fixation of β-CD on cotton by a pad-dry-cure process. The procedure is presented in Figure 4.8 [46]. DMDHEU, which is usually used for easy-care finishing of cotton, can form covalent bonds with the –OH groups of β-CD and cellulose and fix the β-CD molecules on cotton fibers permanently. The reaction between cotton cellulose, DMDHEU, and β-CD is shown in Figure 4.9 [47]. Diisocyanate compounds such as hexamethylene diisocyanate can react with hydroxyl groups of textile fibers and cyclodextrin molecules simul­ taneously, and attach the CDs to the fiber. Sanbhal et al. employed oxy­ gen plasma for creation of –OH groups on surface of polypropylene (PP)

O Br -HBr

OH

COOH

COOH

NH

NH

Cotton Cellulose

C=O

NH2

NH

NH2

O

Pad-Dry-Cure NH2

NH2

NH2

C=O

NH

-O-Cellulose

Figure 4.8  Synhtesis and application of polyaminocarboxylic acid for attachment of β-CD to cotton fibers [46].

O

Cell-OH +

HOCH2 HO

N

N

CH2OH OH

+ HOβ-CD

Heat

Cell-OCH2

Figure 4.9  Crosslinking of β-CD on cotton using DMDHEU [47].

HO

O N

N

CH2OOH

96  Frontiers of Textile Materials mesh and grafted the β-CD molecules to the surface-functionalized fibers. Figure 4.10 presents this reaction schematically [48, 49]. Glyoxal can react with the hydroxyl groups of cellulose and β-CD and act as a bridge to connect β-CD to cellulosic fibers like cotton. The crosslinking procedure includes the padding of the fabric with a solution containing 5–10% wt. Glyoxal (as crosslinking agent) and 1–2% wt. aluminum sulfate (as catalyst) with a wet pick up of 100% and drying at 80°C (3 min), followed by curing at 180°C (3 min) [50]. A similar recipe has been used for the attachment of 2-hydroxypropyl-b-cyclodextrin (HP-β-CD) on cot­ ton fabric [51]. Figure 4.11 shows the different crosslinking products of cellulose and β-CD using glyoxal as crosslinking agent [50]. PP fiber

H

OH

Oxygen Plasma

CH3

CH2OH

O

C

N

N

C

Hexamethylene diisocyanate (HD)

O O

O

C

H N

N H

(DMF, 75ºC)

O β-CD

O H3C O

O H N

O

N H

C

O

O

Figure 4.10  Attachment of β-CD to PP fiber using plasma treatment and HDI [48, 49]. Cell-O O-β-CD HC-CH HO OH

Cell-OH + H-C-C-H + HO-β-CD OO

AI2 (SO4)3 Pad-Dry-Cure

Cell-O O-Cell HC-CH HO O-β-CD

Cell-O OH HC-CH Cell-O O-β-CD

Figure 4.11  Possible reactions between cellulose, β-CD, and glyoxal [50].

O

Functional Finishing of Textiles with β-Cyclodextrin  97 A homo-bifunctional reactive dye (Reactive Black 5) which possesses two vinyl sulfone groups was employed by Agrawal and Warmoeskerken for attachment of β-CD to cotton. This dye can covalently bind to the β-CD and cellulose hydroxyl groups simultaneously, acting as a connector, and permanently graft the β-CD on cotton fibers [13]. Hetero-bifunctional reactive dyes including monochlorotriazinyl and vinyl sulfone reactive groups have been also used for attachment of β-CD to cotton fabric [52]. Reactive derivatives of cyclodextrins can fix the cyclodextrin molecule on textiles (such as cotton) via covalent bonding. One of the most common reactive derivatives of β-CD ismonochlorotriazinyl-β-cyclodextrin (MCTβ-CD), which is synthesized through the reaction between cyanuric chlo­ ride and β-cyclodextrin. Figure 4.12 shows a procedure for synthesis of MCT-β-CD [53, 54]. MCT-β-CD is fixed on cotton fibers using a method similar to the fix­ ation of reactive dyes i.e. under alkaline conditions. Due to the covalent bonding between the cellulosic chain and MCT-β-CD, the durability of β-CD on the textile goods is excellent [56–58]. Figure 4.13 presents the fixation process of MCT-β-CD on cotton schematically [9]. Invasan RCD (Huntsman, Switzerland) is a reactive derivative of β-CD which contains monochlorotriazinyl and sulfonic functionalities and is Cl Cl Cl

N

Cl

H2O, NaOH

N

N

0ºC, 1h

Cl

N N

N Cl

N

ONa

β-CD, NaOH

O

10ºC, 12h

β-CD

N N

OH

Figure 4.12  Procedure of the reaction between cyanuric chloride and β-cyclodextrin [54, 55].

N

N OH

OH

HO

O

OH MCT-β-CD, NaOH Heat

Cotton

O

N

HO

Cotton O

HO N O

Figure 4.13  Fixation process of MCT-β-CD on cotton [9, 55].

HO N

N

OH

98  Frontiers of Textile Materials able to bind the cellulosic fibers like a reactive dye at 60 °C (pH = 10 using sodium carbonate). Figure 4.14 shows the chemical structure of Invasan RCD [59, 60]. Ibrahim et al. utilized a MCT-β-CD (Cavasol W7MCT, Wacker, Germany) for functionalization of wool by a pad-fixation (120°C for 10 min) method. Figure 4.15 shows the grafting mechanism schematically [61, 62]. A similar process has been used by other researchers for fixa­ tion of MCT-β-CD on cotton fabric (padding with 10% wt. MCT-β-CD and 10% wt. sodium carbonate, drying at 80°C and curing at 150°C for 5  min) [63–71]. This derivative of β-CD has been grafted on polyamide fabric for improvement of thermal stability and dyeability besides obtain­ ing antibacterial activity, using a similar procedure [72]. Abdel-Halim et al. has used the pad-dry-cure method for fixation of MCT-β-CD (in presence of sodium carbonate in the impregnation bath) on polyester and cotton/ polyester fabrics [73]. Popescu et al. utilized the alkaline hydrolysis of polyester fibers to create reactive –OH groups on the surface of the fibers. MCT-β-CD was able to covalently attach to the surface-modified PET fibers through a process like the reactive dyeing of cotton [74]. O βCD

S

O

O

NH

N N

N

O S

NH

O O

O

S

O OH

CI

Figure 4.14  Chemical structure of Invasan RCD [59].

O SH

OH Wool

N OH N N O

MCT-β-CD, Na2CO3 Heat

Wool HN N N

NH2 O

Figure 4.15  Grafting of MCT-β-CD on wool fiber [61].

HO N O N N S

N OH

+ HCl

Functional Finishing of Textiles with β-Cyclodextrin  99 Nazi et al. synthesized the cyclodextrin itaconite as a novel reactive β-CD by reacting β-CD with itaconic acid in the presence of SHP, which was able to covalently bond to cellulosic fibers [75–77]. Yu et al. used an enzyme catalyzed, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation to convert the hydroxyl groups of β-CD to aldehyde groups which are able to react with the amine groups of wool fibers through a Schiff base reaction [78]. Figure 4.16 shows the mecha­ nism of the reaction. An alternative approach to functionalization of β-CD molecules, is the functionalization of the textile fiber itself. In this way, the reactive groups on the surface of the fibers have the ability to covalently bind to the native or modified β-CD. Ramirez et al. grafted glycidyl meth­ acrylate on cotton gauze after irradiation with gamma beam. Then, β-CD was covalently attached to the functionalized cotton fibers [79]. Thuaut et al. used ion-beam irradiation and glycidyl methacrylate (GMA) for surface functionalization of PP fibers and subsequently cyclodextrins were grafted on it using the reactive epoxy groups pres­ ent on the surface [80]. A similar approach was used by Abdel-Halim et al., in which the GMA was grafted on cotton by electron beam radia­ tion [81]. Activation by plasma treatment was also used by Hirotsu for grafting of GMA on cotton fibers and β-CD was attached on the GMAgrafted fibers [82]. Gawish et al. grafted the GMA on polyamide 6 fab­ ric using a redox reaction. The process was followed by the reaction of β-CD or MCT-β-CD with the GMA epoxy groups attached on the nylon fibers [83]. Benhadi et al. prepared a modified β-CD (Tetradecakis-(2,6-Oallyl)-β-CD) by reacting β-CD with allyl bromide. Cotton fabric sam­ ples were treated with corona discharge plasma and reactive free radicals were produced on the surface of the fibers. The modified β-CD was grafted onto cotton fibers through the reaction with these free rad­ icals. Figure 4.17 shows the chemical structure of the prepared β-CD derivative and the mechanism of grafting on cotton using plasma pre-treatment [84]. CH2OH

Laccase/TEMPO

CH=O

Wool-NH2

CH=N-Wool

Schiff base reaction

Figure 4.16  Schematic illustration of the grafting of β-CD onto wool fiber using Schiff base reaction [78].

100  Frontiers of Textile Materials

O

O HO O

O

O

O O

O

O HO

O O HO

O O

OH

HO O

O OH

O

O

O

O O

Cotton

O O

O

O

OH

O

O O

O

Plasma Treatment

Cotton

Cotton

Figure 4.17  Mechanism of grafting Tetradecakis-(2,6-O-allyl)-β-CD on cotton using plasma activation [84].

4.5 Functional Properties Obtained by Attachment of β-CD on Textiles The ability of cyclodextrins to form inclusion complexes with various com­ pounds made them a suitable candidate for usage as a carrier for different finishing agents like essential oils, antibacterial agents, drugs, flame retar­ dants, etc. The attachment of the inclusion complex of β-CD and any of the above-mentioned functional compounds, confers the same functionality to the textile substrate. It also affects the dyeing and water absorption properties of textile fibers. β-CD molecules attached to textile fibers are able to form inclusion complexes with the pollutants in water or air and the β-CD finished textiles can be used as filters for decontamination of water and air. In this section, different functional properties of textile materials, which are obtained through attachment of β-CD, are reviewed.

4.5.1 Antimicrobial Activity and Drug Delivery Several compounds are usually used for antimicrobial finishing of textiles. Triclosan, essential oils, silver and zinc oxide nanoparticles, N-halamines,

Functional Finishing of Textiles with β-Cyclodextrin  101 quaternary ammonium compounds, halogenated phenols, and some plantbased compounds are examples of various antimicrobial agents which have been used on textile materials. The textile material may be only impreg­ nated with the antimicrobial agent, or chemically bind with it. Attachment of the β-CD is a solution for attachment of different antimicrobial agents on textile substrates made of any kind of fibers. Table 4.1 shows the differ­ ent antimicrobial agents which have been applied on textiles through the formation of inclusion complex with β-CD.

4.5.2 Fragrance Release and Anti-Odor Finishing The fragrance finished textiles enable the consumer to enjoy a fresh smell and relax. However, when the fragrance is directly applied to the raw textile, the effect is not permanent and wash-fast. Micro-encapsulation and binding of the micro-capsules on the textile substrate is a commonly used method. This method affects the handle of the fabric inversely [97]. Due to the abil­ ity to form inclusion complexes with the human sweat, β-cyclodextrin finished textiles show deodorizing effect and reduce the undesirable per­ spiration odors. This action can be further improved by releasing the guest molecules (like fragrances) included in the β-CD cavities, over a long period of time [65, 71]. MCT-β-CD treatment significantly reduced the third-hand smoke odor release intensity from the smoke-contaminated cotton fabric (up to 65.5%). The volatile organic compounds of the ciga­ rette smoke were trapped inside the cavities of the β-CD molecules [56]. Sricharussin et al. used sandalwood oil as an aroma-finishing agent on MCT-β-CD grafted cotton fabrics. The fragrance was stable on the MCTβ-CD grafted cotton for 3 weeks, while it disappeared from the non-grafted cotton after 8 days [65]. Wang and Chen, grafted the β-CD host molecules on cotton fabric in the presence of BTCA and SHP by a pad-dry-cure pro­ cess, and loaded the β-CD cavities with essential oils of rosemary, lavender, jasmine, lemon, sandalwood, and rose. The smell of the essential oils was remaining for 20–30 days on the β-CD finished fabrics [97]. These authors reported the attachment of β-CD-essential oil inclusion complexes on cot­ ton fabric using a commercial binder through a pad-thermofixation pro­ cess. The sensorial evaluation results confirmed the lasting of the fragrance for 30 days [98]. They obtained similar results when attached the β-CD to cotton fibers using heterobifunctional reactive dyes and finished with the same fragrances using immersion or spraying methods [52]. Khanna et al. applied different essential oils including eucalyptus, pep­ permint, lavender, jasmine, clove, and cedar wood on cotton fabrics pre­ viously anchored with β-CD or MCT-β-CD. The finished fabrics showed

Active compound

Triclosan and Ag NPs

Berberine natural dye

Triclosan and Ag NPs

Octenidine dihydrochloride

Triclosan

Nano ZnO

Triclosan

Coconut oil

Thymol

Thymol

Triclosan

Textile

Wool

Wool

Cotton/wool Viscose/wool

Cotton

Cotton

Cotton

Cotton

Cotton

Cotton

Cotton

Cotton

Invasan RCD/reactive dyeing

β-CD/pad-dry-cure using CA and SHP

MCT-β-CD/ pad-dry-cure using sodium carbonate

MCT-β-CD/ pad-dry-cure using sodium carbonate

MCT-β-CD/ pad-dry-cure using sodium carbonate

MCT-β-CD/pad-fixation using butyl acrylate

β-CD/pad-dry-cure using BTCA and SHP

β-CD/pad-dry-cure using BTCA and SHP

MCT-β-CD/pad-fixation

β-CD/pad-dry-cure using BTCA and SHP

MCT-β-CD/pad-fixation

Type of CD/attachment method

Table 4.1  Antimicrobial agents and drugs used as β-CD inclusion complexes on textiles.

(Continued)

[59]

[29]

[63, 64]

[87]

[58]

[86]

[50]

[44]

[85]

[28]

[61]

Reference

102  Frontiers of Textile Materials

β-CD/pad-dry-cure using CA and SHP β-CD/pad-dry-cure using BTCA and SHP

Nalidixic acid

Chlorohexidine diacetate

Silver(I) ions

Ag NPs

Miconazole nitrate

Melatonin

Sodium diclofenac

Linoleic, ricinoleic, oleic acids

Methylene blue

Citronella oil

Cotton

Cotton

Cotton

Cotton

Cotton

Cotton

Cotton

Cotton

Viscose/polyester

Cotton and polyester

Per-(2,3,6-O-allyl)-β-cyclodextrin/plasma and conventional thermofixation

β-CD/DMDHEU, pad-dry-cure

Modified β-CD/pad-dry

MCT-β-CD/ pad-dry-cure using sodium carbonate

β-CD and MCT-β-CD/grafting with acrylic acid

β-CD/pad-dry-cure using CA and SHP

MCT-β-CD/electron beam radiation and GMA

β-CD and HP-β-CD/gamma radiation and GMA

β-CD/pad-dry-cure using CA and SHP

Chlorhexidine digluconate

Cotton

Type of CD/attachment method

Active compound

Textile

Table 4.1  Antimicrobial agents and drugs used as β-CD inclusion complexes on textiles. (Continued)

(Continued)

[94]

[39]

[93]

[47]

[92]

[66]

[91]

[30]

[89, 90]

[79]

[88]

Reference

Functional Finishing of Textiles with β-Cyclodextrin  103

Active compound

Methylene blue

Methylene blue

Vitamin E, iodine

3-Chloro-2-hydroxypropyl trimethylamonium chloride

Triclosan

Textile

Polyester

Polyester

Polyester

Polyamide

Polypropylene

β-CD/HDI

β-CD and MCT-β-CD/ pad-dry-cure using CA

β-CD/pad-dry-cure with polyisocyanate

β-CD/multilayer coating

Hydroxypropyl-β-CD/ pad-dry-cure

Type of CD/attachment method

Table 4.1  Antimicrobial agents and drugs used as β-CD inclusion complexes on textiles. (Continued)

[48, 49]

[72]

[96]

[95]

[22]

Reference

104  Frontiers of Textile Materials

Functional Finishing of Textiles with β-Cyclodextrin  105 slow and prolonged release of the essential oils withstanding five washing cycles. The tensile strength and stiffness of the MCT-β-CD treated samples was increased, and the air-permeability of the samples slightly decreased [55]. The fabrics treated with all of the above-mentioned oils, except jas­ mine oil, showed mosquito repellent activity [33]. Complex of β-cyclodextrin and citronella essential oil was attached to wool fabric using BTCA and SHP through a pad-dry-cure method and showed a slow release profile [26].

4.5.3 Improved Dyeing and Printing Attachment of β-CD and its derivatives enables the textile fibers to absorb more dye molecules by inclusion complex, hydrogen bonding or interaction with the side groups of the crosslinking agent used (for example the free carboxylic acid groups of BTCA). Several studies have been done to improve the dyeability and printability of different textile substrates with various synthetic or natural dyes. Table 4.2 shows the different types of CDs and strategies for attachment to different textile fibers with the aim of enhancing their dyeing or printing ability.

4.5.4 Wastewater Treatment Due to the high surface area of textile fibers and nanofibers, they are suit­ able candidates for functionalization and subsequent application as filter media. Cyclodextrin grafted textiles can adsorb dyes, organic pollutants, nanoparticles, pesticides, metal ions, etc., through inclusion complex formation, and/or ionic attraction with them. The studies on removal of various model pollutants using β-CD grafted fibers and nanofibers are summarized in Table 4.3.

4.5.5 Flame Retardant Finishing Veerappagounder et al. grafted cotton fabrics with MCT-β-CD (exhaus­ tion method) and β-CD (BTCA+SHP method) and applied a commer­ cial flame retardant compound (di-ammonium phosphate) on the grafted fabrics. These samples showed effective flame-retardancy which was sta­ ble after 20 washing cycles in case of MCT-β-CD grafted samples and 40 washing cycles in case of β-CD + BTCA grafted sample. The finished samples showed negligible change of tensile, whiteness, and hand values [57]. Cotton fabric grafted with Urea phosphate/β-cyclodextrin inclusion

Type of CD/attachment method

MCT-β-CD/pad-fixation

β-CD/pad-dry-cure

β-CD/pad-dry-cure using BTCA and SHP

β-CD and MCT-β-CD/pad-dry-cure using BTCA and SHP

MCT-β-CD/pad-fixation in presence of DMDHEU

MCT-β-CD/pad-fixation

β-CD/exhaustion in presence of CA (80°C)

6A-O-triazine-crosslinked-β-CD/reaction at 80°C in presence of NaOH

MCT-β-CD/pad-dry-cure using sodium carbonate

Textile

Wool

Wool

Wool

Wool

Wool/polyester

Cellulose/wool

Cotton

Cotton

Cotton

Improved printability with reactive and natural dyes

Enhanced dyeability with β-naphthol azo dye

Improved uptake of natural dye (parijatak flowers)

Improved printability with reactive dye

Enhanced printability with disperse dyes

Improved dyeing with acid dyes

Improved dyeing with Berberine natural dye

Improved natural dyeing

Improved printability with acid, reactive, and disperse dye

Action

Table 4.2  Applications of β-CD for improvement of dyeing and printing of textiles.

(Continued)

[69]

[101]

[100]

[85]

[62]

[27]

[28]

[99]

[61]

Reference

106  Frontiers of Textile Materials

Type of CD/attachment method

MCT-β-CD/pad-dry-cure using sodium carbonate

β-CD/pad-dry-cure using CA and SHP

β-CD/pad-dry-cure using BTCA and SHP

β-CD/pad-dry-cure using CA

β-CD/pad-dry-cure using CA + SHP

Textile

Tencel

Polyester

Polyester

Polyester and cotton/polyester

Polypropylene

Improved dyeing with disperse, acid, and reactive dyes

Significant improvement in dyeability with cationic dye

Improved reactive-dye absorption

Improving inkjet printing performance

Incorporation of octyl methoxycinnamate (sunscreen agent) for UV protection

Action

Table 4.2  Applications of β-CD for improvement of dyeing and printing of textiles. (Continued)

[43]

[32]

[102]

[40]

[67]

Reference

Functional Finishing of Textiles with β-Cyclodextrin  107

Phenolphthalein Methylene Blue

β-CD/pad-dry-cure using CA and SHP

β-CD/pad-dry-cure using CA, BTCA, or polyacrylic acid and SHP

β-CD/including in a polymerization mixture

β-CD/pad-dry-cure using BTCA and SHP

Modified β-CD/plasma treatment

β-CD/reaction with epichlorohydrin

β-CD/electrospinning

β-CD/electrospinning + crosslinking with BTCA

Polyester

Polyester

Cotton

Polyester

Cotton

Cotton

Polystyrene

poly(vinyl alcohol-coethylene) nanofiber

Copper ion and neutral red

Phenolphthalein

Chrome ion

Bisphenol A

Pb2+, Cd2+, Zn2+, and Ni2+

Pb2+, Ni2+, and Cd2+

Paraquat (N, N′-dimethyl-4,4′bipyridinium dichloride)

β-CD/pad-dry-cure using BTCA and SHP

Polyester

Pollutant

Type of CD/attachment method

Textile

Table 4.3  β-CD grafted fibers and nanofibers used for wastewater treatment.

[105]

[104]

[20]

[84]

[102]

[103]

[23, 24]

[25]

[36]

Reference

108  Frontiers of Textile Materials

Functional Finishing of Textiles with β-Cyclodextrin  109 complex showed enhanced thermal behavior (based on TGA analysis and nitrogen content measurement) compared with the untreated fabric [106].

4.6 Conclusion β-CD can be used for chemical finishing of different textile fibers. It can be used on textiles in its native form or after chemical modification. One of the most commonly used derivatives of β-CD is MCT-β-CD. β-CD and its derivatives can be attached to textile fibers through different meth­ ods. The β-CD-grafted textiles may obtain medical, anti-odor, fragrance release, antibacterial, and flame-retardant properties, after impregnation with appropriate functional agents. Also, β-CD-grafted textile fibers have the ability to remove several types of pollutants from aqueous media. The dyeability and printability of β-CD-grafted textiles are generally improved. The literature review shows that β-CD-grafting has the potential to expand the applications of textiles in different fields of application.

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5 Synthesis of Nanomaterials and Their Applications in Textile Industry Rizwan Arif 1*, Sapana Jadoun1 and Anurakshee Verma2 1

Department of Chemistry, Lingaya's Vidyapeeth, Faridabad, Haryana, India 2 School of Pharmacy, Lingaya's Vidyapeeth, Haryana, India

Abstract

Unexpected surface properties of nanomaterials viz. their relative low cost make them popular worldwide and due to this reason various type of nanoparticles have been synthesized by the researchers in last few years. After the revolutionary industrial development of twentieth century, manufacture of fabrics, natural fibers such as rayon, nylon and many others, which involve the incorporation of nanomaterials in synthetic materials and fibers, have been increased day by day with significant properties like low cost, chemical stability, and low cost production techniques. Development of nanomaterials is area of great interest for the improvement of existing functionality for the synthesis of new textile products with different properties and functions in single textile material. In last few years, significant improvement has been found in textile technologies like coloring, digital printing on textiles, and smart fabrics in which nanoparticles play key role in technological evolution because of their surface properties and for attaining new properties like flame retardant properties, antibacterial activity, and analyzed for special ultrathin fibers functionalization. In present chapter, we have reviewed the different methods for the synthesis of nanomaterials and their applications after the incorporation of nanomaterials into textiles. Keywords:  Nanomaterials, textile, fibers, antibacterial activity

*Corresponding author: [email protected] Mohd Shabbir, Shakeel Ahmed, and Javed N. Sheikh (eds.) Frontiers of Textile Materials: Polymers, Nanomaterials, Enzymes, and Advanced Modification Techniques, (117–134) © 2020 Scrivener Publishing LLC

117

118  Frontiers of Textile Materials

5.1 Introduction Researchers are working for the production and developments of textile materials and in view of their potential applications, great work have been done. Due to their low cost, resistance to corrosion and excellent mechanical properties made these materials, a subject of high interest. Polyester fabric was developed as the synthetic fiber and it has used widely in textiles, tire production, automobile seats and dyeing industry. Various significant methods for the improvement of flame retardancy and thermal stability of textile materials are also reported [1]. Approaches of nanomaterial sensors, developed by mechanical, thermal, chemical, or magnetic means is kind of responding approach which is very much significant in textile in wearable technologies due to its capability to converting passive wearable into active wearable. In last few years researchers have been focused on selected wearable actuator materials like metal nanoparticles, electro active polymers, and conductive polymers [2]. Textile industry currently served as one of the most beneficial sector in area of nanotechnology. Incorporation of nanomaterial in textiles increased the durability of fabrics, reduced the cost of production, and offers many advantages. Due to the reason, nanotechnology has attracted scientists to the textile industry and hence, the use of nanotechnology in the textile industry has increased rapidly [3]. Textile industry currently served as one of the most beneficial sector in area of nanotechnology. Incorporation of nanomaterial in textiles increased the durability of fabrics, reduced the cost of production and offers many advantages Due to the reason, nanotechnology has attracted researchers to the industry textile and hence the use of nanotechnology in the textile industry has increased rapidly [3]. Textile industry is a significant area which provides financial and employment support to majority of people but due to the problem of dirt and microbial contaminants, which affects the quality of cotton fabrics, there is a need to develop an alternative method for the textile industry. Various types of nanoparticles like silver, chitosan, silicon dioxide, titanium dioxide, and zinc oxide have been synthesized to avoid the contamination of fabrics through microbes. Plant extract serve as reducing and coating agents as many bioactive molecules viz. phenols, lipids, carbohydrates, enzymes, and proteins are present, used by many of the scientists to synthesize the nanoparticles by an ecofriendly, efficient, and cost effective methods [4]. Textile materials like cotton, wool, silk, etc., provide ideal conditions for many drug resistant pathogens. Contamination by microorganisms may lead to emission of unpleasant odors, discoloration, infectious diseases,

Synthesis and Applications of Nanomaterials  119 and undesirable change in aesthetic value of textile materials. To overcome these problems and to improve antimicrobial modifications of textiles have been used in last few years but due to their toxicity to the environment and low durability, many efforts have been made to investigate the effects of nano science and nanotechnology in textile industry which play an important role in the functional finishing of different textile materials [5]. A new area of research, medical textiles, an environmental friendly approach is safely employed for the development of functional biomedical materials and fiber technology in medical fields in recent years [6].

5.2 Synthesis of Nanomaterials Highly intense ultrasound wave has been exploited for the synthesis of novel nanomaterials, insertion of nanoparticles into mesoporous materials and deposition of nanomaterials on ceramic and polymeric surfaces. This technique was also developed for the synthesis and deposition of nanoparticles on various textile substrates [7]. Fouda and his team synthesized zinc oxide (ZnO-NPs) nanoparticle as a multifunctional medical textile by using proteins secreted by isolated fungus Aspergillus terreus (AF-1) and investigated their minimum inhibitory concentration (MIC) and in vitro cytotoxicity onto cotton fabrics [6].

5.2.1 Preparation of Chitosan Nano-Fibers Nano-fiber mats were prepared by blending the aqueous solution of polyvinyl alcohol (PVA) with varying molar mass in 92/8, 85/15, and 80/20 ratio for enhancing electrospin ability and to induced the antibacterial activity. The solution of synthesized chitosan derivatives and pure chitosan were prepared in appropriate concentration and mixed with the PVA or chitosan blends to electrospun as fibers and conductivity of PVA/ Chitosan, PVA/Chitosan/thiol-chitosan and chitosan iodoacetamide solutions has been investigated [8]. In electrospinning process, these solutions loaded into a 10-ml plastic syringe attached to a blunt 22-gauge stainless steel hypodermic needle and used as a nozzle. For charging the solution Glass Man high voltage source was used. Spinning flow rate was found as 3 L/min and samples were collected on aluminum sheet. The designed and synthetic scheme for the preparation of nano-fiber of thiol-chitosan and iodoacetamide-chitosan after the treatment of polyester and without treatment is shown in Figure 5.1.

120  Frontiers of Textile Materials Step I R

Cl– CH3 NH +

H3C

O

+

OH

R

N

O

CH3

R O

O

O N O

+

N O

NH H3C

H O

OH

H

O H

H H

OH

OH

NH2

O

OH

O H

H H

OH

OH

NH2

OH H –

O

R = –SH (Thiol chitosan) R = –I (chitosan iodoacetamide)

R

R

NH

O

O O N O

O

Reactive NHS oster

H3C HO

H2O pH 5

Chitosan Where:

+

HN

NHS

Unstable reactive acytisource oster

EDAC,HCI

Step II

DMF O HO N O

DMF

N

H3C Cl – + CH3 NH

CH3

H3C Cl – + NH

NHS

OH H H

OH

OH

O N O

O H

H O

NH

+ OH

O H

H H

OH

OH

NH2

OH

Chitosan derivative

O

Figure 5.1  Synthetic scheme for the preparation of chitosan derivatives (with permission from license number: 4607090172247, Elsevier and Reference [8]). https://s100.copyright. com/CustomerAdmin/PLF.jsp?ref=29252fd4-d04c-4209-8209-f8d3e0f3ecc5

5.2.2 Preparation of Polyethylene Glycol Capped Silver Nanoparticles (AgNPs) Silver nanoparticles (AgNPs) have been synthesized by research team of Hebeish by using sugar as reducing agent and polyethylene glycol (PEG) as the stabilizing agent (Figure 5.2). The synthesized silver nanoparticles were applied with butane tetra carboxylic acid (BTCA) and sodium hypophosphate (SHP) as a catalyst and incorporated in cotton fabric at various concentrations [9a]. The cotton fabric was padded in an aqueous solution of 5% BTCA and SHP and treated fabric was then filled with solution of nano-silver. Treated fabrics were washed and dried at standard conditions. Mandal and coworker also synthesized silver nanoparticles by using PEG H O

H O n

n

O H

AgNO3 + H O PEG

nO

H H

O

nO

H H O

O H

H

+ + + + Ag + + + + +

H n

n

(aq)

O

O

H O O H

n

Sugar

H

O n

H

n

O

H

O O H

O H Ag NPs Capped by PEG

Figure 5.2  Schematic representation for the synthesis of PEG capped silver nanoparticles (with permission from license number: 44610190757549, Elsevier and Reference [9]). https:// s100.copyright.com/CustomerAdmin/PLF.jsp?ref=91bd3050-d421-4940-b7d9-46059b5e1844

Synthesis and Applications of Nanomaterials  121 (0.168 g) in double distill water added to an aqueous solution of silver nitrate (0.01M) in 10 ml distill water. Sodium borohydride solution (0.1 M, 1.5 ml) was added to the above content as a reducing agent and stirred for 10 min. Color was changed to dark green due to reduction of Ag+ to Ag0. Same procedure was employed for Triton X-100 capped silver nanoparticles (Tx capped AgNp) and for mixed PEG-Tx capped AgNp. In absorption spectra a characteristic peak of the silver surface plasmon resonance (SPR) at 405 nm and in fluorescence spectra an emission band appears at around 595 nm indicates the formation of AgNPs. From SEM images it was concluded that PEG capped silver nanoparticles distributed uniformly and non-agglomerated in the collagen sponge as compared to AgNP without PEG. However, it has also been found that mixed PEG–TX capped AgNPs are more stable with lower sizes, i.e., 30–60 nm range [9b]. Energy dispersive X-ray spectra (EDS) also showed signals of carbon and oxygen atoms in addition to the strong signals of silver atoms (Figure 5.3).

(a)

(b)

C Ag

(c)

(d)

2000 Ag

1500 O 1000 500

Ag 0

0

1

2

3

4

5

Figure 5.3  SEM micrograph of PEG-Tx capped AgNPs at concentrations of (a) 0.3 mM, (b) 0.6 mM, and (c) 0.9 mM, respectively (d) EDS spectra of AgNPs capped by PEG–TX mixed systems (with permission from license number: 4706950035173, Elsevier and Reference [9b]). https://s100.copyright.com/CustomerAdmin/PLF. jsp?ref=7b2922e4-3875-47ce-98fa-0bf946d84eca

122  Frontiers of Textile Materials

5.2.3 Preparation of Silk Textile Nano-Composite Materials of TiO2 Nanoparticles Surface modification technique has been employed for the development of TiO2/TiO2–Ag nanoparticles (NPs) and multifunctional silk textile nano-composite materials by silk functionalization. These synthesized nanoparticles have been modified by using TiO2/TiO2–Ag (1 g) nanoparticles which dispersed into 100 ml aqueous solution of 3-(3,4-dyhydroxy​ phenyl) propionic acid (DHBPA) (15 mg). Refluxed the mixture for 10 min at room temperature and centrifuged at 8000 rpm for 10 min. Solid product was washed thoroughly with distill water, dried at 40°C and assembled on silk substrate by covalent linkages (Figure 5.4). Due to strong bonding, silk fibroin fabric (SFF) and the nanoparticles form a stable composite system and endowed with significant UV protection properties [10]. The antibacterial properties against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa were also determined.

5.3 Synthesis of Nano-Fiber Based Hydrogels (NFHGs) Textile materials have generated a considerable interest in the medical field in mono-filament, multifilament, woven, and nonwoven structures as scaffolds TiO2

Ag

HO

O OH

HO BTCA

(DHBPA)

X

OH

X

NH2

Silk fibroin fiber

OH

OH OH OH OH OH

NH2

Silk fibroin fiber

BTCA

NH2 OH

O H2C C O HC C HC C O H2C C O

OH

NH2 OH

(DMDHEU) O C

OHCH2 N OH

N CH2OH OH

Figure 5.4  Schematic diagram of the surface-modified TiO2–AgNPs (with permission from license number: 4610211233460, Elsevier and Reference [10]). https://s100. copyright.com/CustomerAdmin/PLF.jsp?ref=030895cf-055f-4ae7-a424-154b8ca03e38

Synthesis and Applications of Nanomaterials  123 wound dressing, masks, and surgical gowns many other medical textile products are available in the market with remarkable antimicrobial properties. Some of the researcher also incorporated the antimicrobial agents in textiles substrates for production of mildew stain proof products and to prevent microbial growth on textiles but these antimicrobial agents are highly toxic and by-products [11]. In this aspect, researchers have been working to produce environmental and ecofriendly antimicrobial agents from natural substances for the treatment of textile products with better antimicrobial properties. In many of the research papers various strategies have been applied for the synthesis of NFHGs (nano-fiber based hydrogels) like electrospinning technique, 3D printing, weaving, freeze drying, and molecular self-assembling methods with various biological applications like tissue drug delivery, engineering, intelligent actuator, sensing, and water separation [12].

5.3.1 Electrospinning Nano-fiber based hydrogels (NFHGs) with various potential and structural applications has been designed and fabricated. Electrospinning technique has been employed for fabricating nano-fibers, which shows great potential in synthesizing nano-fiber based hydrogels with varied composite structures and significant advantages of abundant raw materials and controllable single fiber morphologies [13, 14]. NFHG derivatives have also been developed by the combination of traditional hydrogels with electrospun nano-fibers. Membranes of electrospun poly(l-lactide) nano-fibrous were coated with poly(lactide-co-ethylene oxide fumarate) and hydroxyapatite by cutting it into many rectangular pieces, then accumulated layerby-layer and compressed. After the cross linking treatment, poly(l-lactide) nano-fiber reinforced laminated poly(lactide-co-ethylene oxide fumarate)) hydrogel was obtained. Bonding of nano-fibers and hydrogels make the composite having significantly higher mechanical strength than that of the pure poly(lactide-co-ethylene oxide fumarate) hydrogel [15, 16].

5.3.2 Weaving Many researchers have been used weaving method in which weave can be prepare various fabric construction by designing yarn type, arrangement for the manufacture of traditional fabric. The 3D fabrics also are successfully prepared by combining the nano-fiber with traditional interweaving method. Wu and his team also prepared a novel interwoven-aligned conductive nano-fiber– hydrogel composite by interweaving nano-fiber yarns within hydrogel for mimicking purpose of the anisotropic cardiac structure [17, 18]. Nano-fiber

124  Frontiers of Textile Materials yarns were also fabricated via wet–dry electrospinning and interweaving method. In weaving process, 3D-printed model fixed with surgical suturing threads as the warp structure and weft thread of nano-fiber yarns was blend closely across the warp yarns. The nano-fiber yarn network with regular interwoven microstructure of parallel-aligned was obtained by this process.

5.3.3 Freeze Drying This is another high efficiency and high performance method has been used widely in the food and materials processing without damaging its 3D structure in rapidly drying wet materials [19–22]. On the basis of this method, different porous materials with different cellular structures viz. grapheme, cellular aerogels assembled with nano-fiber, cellular monoliths, carbon nanotubes, foams, etc., have been successfully prepared [14, 23–26]. In last decades new porous nano-fiber-assembled hydrogels (NFHs) have been successfully synthesized by freeze-drying method with significant water-holding capacity, super elasticity and other excellent properties [21]. Fabrication process consists of ectrospun SiO2 nano-fibers, water, alginate–hydrogel precursor and cross linker of metallic cations. After cutting the flexible SiO2 nano-fibers, homogenized nano-fibers have been prepared by the dispersion of these fibers in water. After this dispersion within metal mold has been carried out and the cross linked SiO2/alginate nano-fibrous composite aerogels were obtained and finally by ionic cross linking the alginate of composite aerogels using an aqueous solution of Al3+ the NFHs were generated.

5.3.4 3D Printing One of the most significant and rapidly developed techniques is 3D printing technique for the designing and synthesis of nano-fiber based hydrogels in large scale due to its various advantages like precise structural formation, facile printing, fast prototype abilities and low cost. The fabrication of 3D structures is carried out by 3D printing technique by computer aided designing through a layer deposition process [27–30]. Hydrogel precursor was used as printing ink for the synthesis of different type of 3D-printing hydrogel.

5.4 Application of Nano Textiles Nanoparticles and surfactants are the carrier medium of textiles surface. Polymeric nanomaterials used for producing nanoscale conventional

Synthesis and Applications of Nanomaterials  125 fibers having very high surface area and permeability, less diameter, and significant filtration properties. Production of nano-composite fibers is one of the significant approaches in the field of nano textile production, which include conductive and communicating textiles, warming, cooling, and textile sensors. After the incorporation of nanomaterials into fibers, mechanical, electrical, optical, or biological properties have been improved [31–34]. Nanomaterial textiles used in fashioned technological clothing, affords an expanded array of properties, eco friendly approach, can reduce the use of water as dry techniques is used for the synthesis of nanomaterials on fabric. Conductive yarns and fibers have been prepared by combining pure metallic fibers with conductive materials. In commercial polymer, addition of carbon nanotube eliminates die swell effect, which in turn enhances the strength of the fibers. Nanoparticles are electrically conductive materials which help dissipate the static charge in these polymeric fibers. Surface properties of fabric material can be enhanced by implementing using nanotechnology. A revolutionary trend in the field of textiles industry for the humanity has been come out after the development of nanotechnology [35–38]. Amani and his co-worker [39] used the mixture of zinc acetate and corn silk for the production of polyester fabric with multifunctional and hydrogel properties. The polyester fabric was treated through in situ synthesis of ZnO nanoparticles along with corn silk in one-step method (Figure 5.5). The antimicrobial activities and the cytotoxicity of the treated fabrics were investigated to study various properties of the fabric (Table 5.1). Treated fabric showed significant antimicrobial activities against Staphylococcus aureus, Escherichia coli bacteria, and fungus Candida albicans and cell viability were found to be 87% on human cells on the zinc oxide nano-composites treated fabric.

e

O2

h

Corn silk

e Amide

O2

+

h

h

h

–

Hydroxyl

e Methylene

e

e

O2 e

h

+

h

h

h

–

OH

+

H2O

Undoped ZnO

Reduction

O2

hydrazine > hydroxylamine > urea); The pre-treatments performed do not lead to significant degradation of PAN-M; The functionalized PAN-M with amines can be uniformly dyed with acid dyes (Blue acid R) that have affinity for the newly introduced functional groups (–NH– or –NH2).

Other research has shown that the simplest substance that can be used to functionalize any acrylic fiber is NaOH, at elevated temperatures [65–69]. Through these functionalizations, the acrylic fibers become more accessible for both water and dyeing solutions. Functionalization with NaOH diversifies the field of use of functionalized acrylic fibers, including ion exchange membranes [33, 34], and adsorbents for metal ion from wastewaters [70, 71]. The size of the NaOH concentration dictates the degree of ­functionalization/transformation of the CN groups into amide or carboxyl groups. If the acrylic fiber is PAN-M type, which also contains vinyl acetate in the molecular structure, then NaOH causes the breaking of ester group and a new functional group is formed, the OH group. This operation is known as saponification. The functionalization of PAN-M fibers can be accomplished with other basic amino compounds (hydroxylamine, dihydroxy ethylene amine, chitosan) in the absence or presence of NaOH [67–69]. The chemical transformations of the ester groups (OOC– CH3) and the CN groups are shown in Table 11.1. The functionalization degree is dependent on working conditions: reagent concentrations, duration and temperature. The presence of new functional groups was confirmed by IR analysis. By comparing the FTIR spectra of the

Hydroxylamine

OH and amidoxime

NH2

N OH

Chitosan

-

C

NaOH

Functionalization agent

OH and CO–NH2/COOH

New functional groups

Table 11.1  New functional groups in PAN-M.

- By conversion of OCOCH3 groups during N-acylation reaction; - By conversion of CN groups during amylosis reaction

- Not conversion of OCOCH3 and CN groups

- By conversion of OCOCH3 groups during saponification reaction; - By conversion of CN groups during alkaline hydrolysis

Explanation

SO3Na

(Continued)

SO3− + NH3 −Chitosan

SO3Na

Final acid group from the end of PAN-M chain

Multifunctionalizations of Textile Materials  233

Chitosan

NH

O

- By conversion of OCOCH3 groups during saponification reaction; - By conversion of CN groups during N-acylation reaction;

Chitosan + NaOH

OH and amide monosubstituted as

C

- By conversion of OCOCH3 groups during N-acylation reaction - By conversion of CN groups during amination

Explanation

Dihydroxy ethylene amine

Functionalization agent

OH and a morpholine ring

New functional groups

Table 11.1  New functional groups in PAN-M. (Continued)

SO3Na

SO3Na

(Continued)

Final acid group from the end of PAN-M chain

234  Frontiers of Textile Materials

OH and a morpholine ring

OH

NH

O

Dihydroxy ethylene amine + NaOH

Hydroxylamine + NaOH

OH and hydroxamic acid

C

Functionalization agent

New functional groups

- By conversion of OCOCH3 groups during N-acylation reaction; - By conversion of CN groups during N-acylation reaction.

- By conversion of OCOCH3 groups during saponification reaction; - By conversion of CN groups during N-acylation reaction;

Explanation

Table 11.1  New functional groups in PAN-M. (Continued)

SO3Na

SO3Na

Final acid group from the end of PAN-M chain

Multifunctionalizations of Textile Materials  235

236  Frontiers of Textile Materials non-functionalized acrylic fiber with the functionalized ones, it is clear that by functionalization there are changes/decreases in the height of the peaks corresponding to the CN group (2241 cm−1), the acetate group (1732  cm−1), and the appearance of new peaks corresponding to the new functional groups (Figures 11.3–11.6). The new functional groups cause the following modifications for the absorption bands: • Carboxylic: 1732 cm–1 (assigned to C=O stretching (s) and 1233 cm−1 for C–O stretching vibration (s)); instead, the bigger height of the peaks at 1630 cm−1 (C–O stretching (s), 1565 cm−1 (N–H out of plane (m)) confirm the presence of amide groups (Figures 11.3–11.6);

% Transmittance

2

1

4000

3000 2000 Wavenumbers (cm–1)

1000

Figure 11.3  FTIR spectra for control sample (1), PAN-M functionalized with NaOH (2).

% Transmittance

3

2

1

4000

3000 2000 Wavenumbers (cm–1)

1000

Figure 11.4  FTIR spectra for control sample (1), PAN-M functionalized with hydroxylamine (2) and with hydroxylamine + NaOH (3).

Multifunctionalizations of Textile Materials  237

% Transmittance

3

2

1

4000

3000 2000 Wavenumbers (cm–1)

1000

Figure 11.5  FTIR spectra for control sample (1), PAN-M functionalized with dihydroxy ethylene amine (2) and with dihydroxy ethylene amine + NaOH (3).

% Transmittance

3

2

1

4000

3000 2000 Wavenumbers (cm–1)

1000

Figure 11.6  FTIR spectra for control sample (1), PAN-M functionalized with chitosan (2) and chitosan + NaOH (3).

• Amidoxime groups (Figure 11.4): 1645 cm−1 (C=N stretching, (m)), 3650−3150 cm−1 (N–H and O–H stretchings, (s)) and near 937 cm−1 (N–O stretching, (w)) [69, 72–74]. • Hydroxamic acid groups (Figure 11.4); 1670–1600 cm−1 for combination of C–N and C=O stretching (m-s), 1534 cm–1 for N–H deformation and C–N stretching (m), and near 937 cm−1 for N–O stretching (w) [69, 72–74]; • Amidines at 1628 cm−1 (C=N stretching (m-s)) confirmed by Figure 11.5. A component of amidines is a morpholine. The characteristic frequencies for morpholine: 925–845 cm−1 (ring deformation for morpholine group (v)), 2972– 2830  cm−1 (C–H stretching (v)), 1390–1275 cm−1 (C–H

238  Frontiers of Textile Materials skeletal (v)), 1124–1175 cm−1 (C–N stretching (v)), 1140– 1000 cm−1 (C–O stretching (v)); • Monosubstituted amide in case of functionalization with chitosan + NaOH (Figure 11.6); the presence confirmation of this amide is given by the peaks from 1630 cm−1 (for C=O stretching vibration), 1535 cm−1 (assigned for combination of N–H deformation and C–N stretching vibrations); the peak at 3220 cm−1 (assigned to N–H stretching vibration) appears also. Decreasing the peak height at 2241 cm−1 confirms the conversion of CN groups into new groups such as COOH, amidoximes, amides or hydroxamic acid. Decreasing the peak height at 1732 cm−1 confirms the breakdown of the ester groups; new, more reactive, OH-type functional groups are formed. These groups generate the modifications of the absorbance bands from 3385 cm−1 (OH stretching (s)), 1069 cm−1 (C–OH stretching (s)), and near 1400 cm−1 deformation (m)).

11.3.3 Dyeing of PAN-M Functionalized with Basic Reagents The chemical changes made by these basic reagents on PAN-M fibers were highlighted by the tinctorial method: 1) dyeing with acid dyes [68]; 2) dyeing with reactive dyes [67]. The K/S (measured on a Spectraflash SF 300 spectrophotometer) indicates, indirectly, the degree of functionalization of treated/functionalized and dyed samples. a) Dyeing with acid dyes In this case, in the dyebaths having a low pH made by the presence of oxalic acid (pH = 4.5), were added one of following dyes: C.I. Acid Red 118 (C.I. 26410), C.I. Acid Violet 1 (C.I. 17025), C.I. Acid Red 26 (C.I. 16150), or C.I. Acid Red 18 (C.I. 16255) [68]. These dyes are monoazo type and contain 1-3 sulfonyl groups in addition to other substitutes (OH, NH2, or CH3) attached to the coupling component of naphthalene type (Table 11.2). The functionalized PAN-M dyeing with anionic dyes, such as dye-SO3− Na +, proceeds in two steps (Figure 11.7): 1) protonation of the amine groups with an acidic solution (made with oxalic acid); 2) proper dyeing when these protonated functional groups attract electrostatic anions of the acidic dye. The sites of dyeing with acid dyes of the acrylic fiber modified by functionalization with amines, are even the amino groups, newly formed (Table 11.1) by conversion of CN from acrylonitrile comonomer.

Multifunctionalizations of Textile Materials  239 Table 11.2  Characteristics of acid dyes used for dyeing of functionalized PAN-M. Characterization Chemical structure of acid dyes

Number of SO3Na groups

Molecular weight (g)

1

540.619

2

512.37

2

480.42

3

604.47

H2N H3C

N=N HO

O=S=O N

H2C

SO3Na

CH3

C.I. Acid Red 118 SO3Na

-

O

N

+

H2N

N=N

O

HO SO3Na

C.I. Acid Violet 1 CH3

HO

H3C

SO3Na

N=N

SO3Na

C.I. Acid Red 26 HO NaO3S

N=N NaO3S SO3Na

C.I. Acid Red 18

240  Frontiers of Textile Materials CH3 (

CH2

CH ) ( CH2 x C R1 NH

CH ) ( CH2 y OH

CH )

H+ X protonation z

t =10 minutes

CH3 (

CH ) ( CH2 x

CH2

C +

R2

CH3 CH )x ( CH2 C R1

CH2 +

NH2

CH )y ( CH2 CH ) z OH

R2

NH2

CH )

z

R2

Protonated PAN - M

Functionalized PAN - M

(

R1

CH ) ( CH2 y OH

+ Dye SO-3Na+ dyeing Na+X-

CH3 (

CH2 SO-3

CH ) ( CH2 x C R1 +

NH2

CH ) ( CH2 CH ) y z OH

R2

Dye Protonated PAN - M

Dyed PAN - M

Figure 11.7  Scheme for the protonation of functionalized PAN-M and for dyeing of this fiber (R1 is =O (in amides or hydroxamic acid); =N–OH (in amidoximes); R2 is H (in amides and amidoximes); OH (in hydroxamic acid); pyranose ring from chitosan; morpholine ring; X is HCOO–COO−).

In acidic environment realized with oxalic acid, these groups become protonated and the chemical reaction that underlies dyeing can be written according to Figure 11.7. Many types of interactions between the protonated fiber and the dye were observed: ionic bonds, polar and hydrophobic sometimes. The values of K/S obtained after dyeing depend on the modifications from fibers through the functionalization, by the ability of protonation and the structure and dyes affinity. The strength of the electrostatic bond between the dye and the protonated fiber is dependent on the dye structure, the affinity of the acid dye for the functional group of chemical modified PAN-M and the dyeing conditions (pH, temperature, time, shaking). The ability to dye depends on how easily can be protonated the acrylic fiber functionalized, in the acidic environment of the dyeing. The protonation ability of -C(NH-R2)–R1 groups existing in the functionalized fibers depends on the particularities to the respective group and the interactions with the nitrogen atom, basic center. Therefore, the protonation ability depends on the strength of the effects exerted by R1 and R2 substitutes. The K/S values depend on the dyeing conditions, the number of acidic groups in the dye and the functionalization conditions: the type and concentration of the functionalization agent, the temperature and the duration of the functionalization.

Multifunctionalizations of Textile Materials  241 Functionalization with 5% hydroxylamine resulted in the highest K/S values, regardless of the dyeing conditions (acid dye type and pH); for dyeing with 1 g/L acid dye, in a mildly acidic environment (pH = 4), K/S = 1.5 to 12 values were obtained; and when the pH is 1.5, the K/S values are higher, between 2.2 and 20.8. For each acid dyes used in dyeing process, the variation of K/S is the tinctorial answer for chemical changes suffered by the PAN-M, for the protonation ability, for basicity of functional groups and their density (frequency), for the dye-fiber interactions and not least the particularities of dye used (planarity, molecular volume, nature of the substitutes and their positions). b) Dyeing with reactive dyes The dyeing with reactive dyes was performed on PAN-M functionalized with chitosan, in basic (NaOH) environment. Three Procion dyes (Procion Red H-E3B (C.I. Reactive Red 120), Procion Red H-EXL, Procion Brilliant Red H-EGXL) [67] were used for dyeing (Table 11.3). The ability to dye with reactive dyes of the acrylic fiber functionalized with chitosan, in basic medium (NaOH) has been studied; this depends on the affinity of the new functional groups relative to the reactive group (the chlorine atom) of the reactive dyes. Functionalization with chitosan in the presence of NaOH consists of the introduction of a new monosubstituted amide-like group (CO–NH–­ chitosan). This takes place in two stages:

1) transformation of the CN group into COOH under the action of NaOH; 2) the reaction of COOH from saponified fiber with NH2 from chitosan, with monosubstituted amide formation (CO–NH– Chitosan) as a result of an N-acylation.

Chitosan thus attached to the acrylic fiber has two types of reactive groups: primary OH groups (on the C6 atom) and NH2 groups (at the C2 atom); a multifunctional acrylic fiber is thus achieved. The capacity of primary OH groups of chitosan to react with chlorine from the reactive dyes depends on the pH in the dyebath, as follows: (a) in the strongly acidic medium (pH = 1 made with oxalic acid and T = 100°C), ether bridges can be formed between some primary OH groups of chitosan and the Cl atoms of the reactive dyes; however at this pH there is also protonation

N

H

N

SO3Na

O

H

Procion Red H-E3B

N

SO3Na

N

N

Cl

N

SO3Na

NH

Chemical structure of reactive dye

NH

NaO3S

N Cl

N N

N H

O

H

N

SO3Na

N SO3Na

OH 0

Cl 2

(Continued)

6

SO3Na

Characterization groups number

Table 11.3  Characteristics of the reactive dyes used in the dyeing of functionalized PAN-M.

242  Frontiers of Textile Materials

N

N

H

HO3S

N

NH

N

H

N

N

Procion Brilliant Red H-EGXL

N

SO3H

N

O

OH

Cl

Procion Red H-EXL

NaO3S

SO3Na

SO3H

N

Na

Cl

N

SO3Na

N

N

Chemical structure of reactive dye

HO3S

NH

NH

N

NH

N

Cl N

OH

COONa

SO3H

N N

HO3S

2

0

1

2

OH

Cl

6

4

SO3Na

Characterization groups number

Table 11.3  Characteristics of the reactive dyes used in the dyeing of functionalized PAN-M. (Continued)

Multifunctionalizations of Textile Materials  243

244  Frontiers of Textile Materials of NH2 groups free of chitosan (with the formation of NH3+ groups) which also allows the dyeing with acid dyes; (b) in the basic environment and high temperature only dyeing with reactive dyes is favored as a tinctorial response of the formation of the ether groups between the functionalized fiber (at the primary OH of chitosan) and the chlorine atom from the reactive dyes. The K/S obtained are: 1) between 0.15 and 1.8 at the 9% dyeing with reactive dyes in acidic medium (pH = 1, T = 100°C and 30 min); 2) between 0.15 and 0.45 on dyeing with 9% reactive dyes in basic medium (pH = 10, T = 100°C and 30 min). In all cases, the dyed samples have very good resistance to wet treatments.

11.4 Multi-Functionalization of Acrylic Fiber by Grafting with Polyfunctional Agents As polyfunctional agents (Figure 11.8) the following were used: a) chitosan having two types of reactive groups: OH and NH2; b) M  CT-β-CD that has two types of reactive groups: the chlorine in the MCT group and the primary OH groups from β-cyclodextrin.

11.4.1 Multifunctionalization of PAN Fiber with Chitosan The literature indicates how to prepare the hydrophobic product: chitosan/ PAN/Fe3O4–zeolite (ZSM-5) nanofibers. These nanofibers were coated on the surface of the sponges to absorb many oil types (lubricating oil, motor oil and pump oil) from water surfaces. The composite can be easily reused in water-oil separation for many cycles [75]. In another study [76], the PAN nanofibrous substrate was first treated with 1M NaOH solution and then coated with chitosan solution to form a composite membrane. This functionalized membrane was immersed in different anionic dye solutions (6 h) to complete anionic dyes fouling process (to stabilize chitosan) and then washed by deionized water and stored in a water bath before use. These functionalized membranes have excellent filtration performance for anionic and cationic dyes separation.

Multifunctionalizations of Textile Materials  245 NH2

HO

O OH

OH O

CH3 NH

O

O

O

O OH

NH2

O

OH O NH2

CH3

O O

NH O OH

OH O

O n

OH

NH2

Chitosan N

Cl N

ONa

ONa N

N

Cl N

N N

HO

beta cyclodextrin

N N

HO O O O HOH O HO O OH

HO O β

HO O HO O O HO HO HO O OH

ONa

Cl

OH HO O O O OH OH OH O OH

MCT-β-CD

O

OH OH

β-CD

Figure 11.8  The chemical structure of the two polyfunctional agents: chitosan and MCT-β-CD.

The multifunctionalization of PAN fibers with chitosan can be achieved by forming two types of chemical bonds: 1) Electrovalent bonds between NH3+ groups of chitosan dissolved in acetic acid and the acidic groups (SO3− or COO− type) which give the anionicity of acrylic fiber [77–80]; 2) covalent bonds (of the ether or ester type) between an acrylic fiber functionalized with basic reagents and then with chitosan [69]. In both cases, the multifunctionalization can be evidenced by dyeing with anionic dyes; this is possible due to the interaction between chitosan and anionic dyes [81–87].

11.4.1.1 Multifunctionalization of PAN-M Fiber with Chitosan by Means of Electrostatical Bonding In the case of multifunctionalization of PAN-M fiber with chitosan by means of electrostatic bonds [77–80], the dyeing with anionic (direct, reactive and acid) dyes can be done in three steps: 1) The protonation of acrylic fiber with an acid to extract the metallic ions from terminal groups SO3− K + , groups which exist into PAN-M fiber, resulting from redox initiating

(

)

246  Frontiers of Textile Materials agent of radical polymerization (K2S2O8 and NaHSO3). The extraction of K+ ion from the terminal acid groups gives an anionic character to these groups. In this way, the terminal anionic groups became free (are SO3− type) and it can form the bindings with amine groups from chitosan (+NH3 groups achieved by a dissolving operation of chitosan in an acid environment). 2) The protonation of chitosan: during the dissolving operation in an acid environment, the chitosan became a polycation, owing to the existence of +NH3 groups. Thus, the terminal groups from the PAN-M fiber were electrostatically attracted by amine groups from the dissolved chitosan. In this manner was formed a complex acrylic fiber–chitosan, which allowed to be dyed both with cationic dyes (specific for acrylic fibers) and with anionic (direct/reactive) dyes (specific for cellulosic fibers because the chitosan is a modified cellulose). Certainly, a high contribution for dyeing process, with anionic dyes had the OH groups from C6 and C3 positions from chitosan because this is a poly (1-4)-2-amino-2-deoxy-beta-D-glucan.  The multifunctionalization way of PAN highlighted is Figure 11.9. 3) The dyeing with 0.5–2% C.I. Direct Green G, 1% and 4% C.I. Reactive Red 45 [77–80], or 0.1–1% acid dyes (C.I. Acid Red 118 (C.I. 26410), C.I. Acid Violet 1 (C.I. 17025), C.I. Acid Red 26 (C.I. 16150), or C.I. Acid Red 18 (C.I. 16255) [68]) at 100°C, 30 min with 5°C/min as heating gradient.

11.4.1.1.1 Dyeing of Multifunctionalized PAN-M Fiber with Chitosan via Electrostatic Bondings

The dyeing of PAN-M fiber multifunctionalized with chitosan PAN-SO3− + NH3−chitosan is possible due the binding of dyes through the following types of bondings [77–79]:

(

)

PAN

SO3– +

PAN-M fiber

+NH 3

chitosan

=

PAN

SO3– +NH3 chitosan

Protonated chitosan

Figure 11.9  Scheme of PAN-M multifunctionalized with chitosan.

Multifunctionalizations of Textile Materials  247 a) Hydrogen linkages between the polar groups of the multifunctional fiber and the sulfonic groups from the direct dyes; b) Ether covalent bonds formed between the primary OH groups of chitosan and the chlorine atoms from the reactive dye molecules; c) Electrostatic/ionic bonds formed between the +NH3 groups (not involved in the multifunctionalization process) of chitosan and the anions of the acid dyes. In all these cases, the K/S depends on the type/concentrations of chitosan used and type and concentrations of dye used in dyeing process. The K/S values vary between 0.2 and 0.6 in case of direct dye, 0.3 and 0.6 in case of reactive dye, and 0.3 and 2.3 in cases of acid dyes. The multifunctionalization with chitosan can permit the dyeing with anionic dyes and the levelness of dyeing is very good by comparison with the levelness obtained with cationic dyes even at a high heating gradient (5oC/min) used during dyeing.

11.4.1.2 Multifunctionalization PAN-M Fiber with Chitosan via Covalent Bonds Grafting of chitosan on the PAN-M fiber functionalized with basic reagents, in the presence/absence of NaOH (NaOH, hydroxylamine ± NaOH, dihydroxy ethylene amine ± NaOH) led to their multifunctionalization [69]. Multifunctionation with chitosan was possible by carrying out the following reaction conditions: the presence of oxalic acid as a catalyst, temperature of 100°C, for 60–120 min. These conditions were necessary to facilitate the reaction between two asymmetric alcohols: chitosan through the primary OH groups and functionalized PAN-M fiber through newly introduced OH groups; ether bridges are formed between chitosan and PAN-M fiber functionalized with amines ± NaOH. The COOH groups from PAN-M fiber functionalized with NaOH may form ester bridges with the OH groups of chitosan.

11.4.1.2.1 Dyeing of Multifunctionalized PAN-M Fiber with Chitosan

In the case of forming the covalent bondings between chitosan and the PAN-M fiber, the dyeing with acid dyes (C.I. Acid Red 88 and C.I. Acid

248  Frontiers of Textile Materials Violet 48) is based on several types of interactions between the two partners (multifunctional PAN-M fiber and acid dye): ionic bonds, polar and hydrophobic sometimes [69]. The C.I. Acid Red 88 dye has led to the highest values for K/S, namely: a) K/S = 1.94 in case of functionalization with hydroxylamine + NaOH and grafting with chitosan; b) K/S = 6.39 in case of functionalization with hydroxylamine and grafting with chitosan. The values of K/S obtained after dyeing depend on the chemical modifications of fiber through the multifunctionalization and the structure, concentration of the dyes. The chemical changes depend on the conditions of functionalization (type, concentration of the functionalizing agent, temperature, duration) and the concentration of chitosan used in the grafting process. The multifunctionalizations of PAN-M fiber could determine the increasing of the utilization fields. Thus, multifunctionalized PAN-Mfibers acquire higher performances: high reactivity, hygroscopicity/wettability, antimicrobial effects (due to NH2 groups from CS), and an excellent dyeability with a nonspecific dyes class. Moreover, all the effects acquired through functionalization/grafting had excellent durability [69].

11.4.1.3 Multifunction of PAN Fiber with MCT-β-CD Attaching β-CD to an acrylic support by grafting is rarely presented in literature. There is a study [88] in which β-CD is physically attached to PAN nanofibers obtained from the electrospinning process. In addition, PAN nanofibers have been chemically functionalized with citric acid (via saponification) and β-CD. Citric acid binds covalently to PAN saponified and forms β-CD ester bridges with many free OH groups; this functionalized acrylic support can capture formaldehyde. The functionalized PAN nanofibers were characterized by ATR-FTIR, SEM, TGA analyses. In another study, electrospinning technology is used to obtain PAN nanofibers functionalized with β-CD and Ag nanoparticles. These nanofibers composite showed stronger antibacterial activity [89]. In literature [90] is presented the case of functionalization of PANMfiber in basic medium (NaOH, hydroxylamine + NaOH and chitosan +

Multifunctionalizations of Textile Materials  249 NaOH) and grafting with MCT-β-CD. This multifunctionalized fiber has acquired the following types of functional groups: • CO-NH2, COOH and OH during NaOH functionalization and OH groups during grafting with MCT-β-CD; • Amidoxime groups during NaOH + hydroxylamine functionalization and OH groups during grafting with MCT-β-CD; • Amide monosubstituted (–CO–NH–chitosan) during NaOH + chitosan functionalization and OH groups during grafting with MCT-β-CD.

11.4.1.3.1 Dyeing of PAN-M Fiber Multifunctionalized with MCT-β-CD

In each case, the multifunctionalized PAN-M fiber has many OH groups derived from β-cyclodextrin, thus being able to interact with the reactive dyes and form covalent bonds. The reactive dyes used are Procion Red H-E3B (C.I. Reactive Red 120), Procion Red H-EXL, Procion Brilliant Red H-EGXL, and their chemical structures are presented in Table 11.3. The structure of these reactive dyes influences the K/S values through the number of the solubilizing groups that there are into the dye and the volume of these groups. The best colorimetric results were obtained on the samples functionalized in basic medium with hydroxylamine and grafted with MCT-β-CD (K/S = 0.45–1.1), being followed by the samples functionalized with another polyfunctional grafting agent, chitosan when the values K/S varies between 0.2 and 0.6.

11.5 Polyethylene Terephthalate: Functionalization Ways It is known that polyethylene terephthalate (PET) fibers come from the esterification reaction of ethylene glycol and terephthalic acid [91–109]. The ester functional groups in the main chain of the PET are not able to react with other chemicals, because are blocked inside of the polymer. The reactivity of this polymer can be improved if the ester groups can be

250  Frontiers of Textile Materials converted in COOH, OH, and NH2 groups; this is possible through chemical or physical treatments that can trigger the functionalization of PET by the emergence of more reactive groups. The reactivity of PET fibers can be altered by reactions that result in the breaking of the ester linkage and the appearance of free OH and COOH groups. This is possible with the following treatments: 1) Saponification with NaOH [91–96] or with a mixture of NaOH with methanol/ethanol [97–99]; 2) Amine treatment of PET [96, 100–102]; 3) Plasma treatment [103–106]; 4) Grafting with different agents enriched in polar groups, on a support functionalized with plasma [107–108]; 5) Grafting with different agents on a support functionalized by saponification [109].

11.5.1 Functionalization of PET with Basic Reagents Two types of PET fibers (recycled from PET bottles and virgin, obtained by synthesis) were functionalized with basic reagents [96]. Recycled PET fibers are obtained from the processing of waste PET bottles at the end of a mechanical recycling or a chemical recycling. As reagents with basic character, NaOH, ethylenediamine and their mixture were used; in these cases, the functionalization treatments are called saponification or aminolysis, respectively. The saponification consisted of the virgin and recycled PET treatment with solutions of 2 M NaOH and aminolysis with solutions of 0.5–2 M ethylenediamine. Also, mixed saponification procedures (2 M NaOH) followed by immediate aminolysis or after 24 h (0.5–2 M ethylenediamine) were tested. When the saponification and aminolysis steps are performed separately, within 24 h, the saponified samples are treated with 1 mL of concentrated HCl, 150 mL of distilled water, 15 min at 20°C, to convert COONa into COOH. In the presence of ethylenediamine, the COOH group participates in an N-acylation reaction, with the formation of N-acylated amines. During these treatments with basic reagents, some of the ester groups of the PET polymer are decomposed and form COONa/COOH, OH and NH2 groups respectively as terminal groups (Table 11.4). The chemical equations underlying the functionalization of PET fibers are as follows:

Multifunctionalizations of Textile Materials  251 Table 11.4  Functional groups in PET after functionalization with basic reagents. New functional group in: Functionalization

Reagents

Recycled PET

Virgin PET

Saponification

NaOH

COO−; HO

COO−; HO

Aminolysis

Ethylenediamine

NH2; HO

NH2; HO

Saponification + aminolysis (simultaneous)

NaOH + ethylenediamine (simultaneous)

COO−; NH2

COO−; NH2

Saponification + aminolysis (individually, after 24 h)

NaOH (first stage) + Ethylenediamine (second stage)

NH2

NH2

a) PET saponification using NaOH solution with 2 M concentration: CH2 CH2 COO

COO CH2 CH2 OOC

CH2 CH2 OOC

COONa +HO

+NaOH

COO CH2 CH2

CH2 CH2 OOC

24 h/20ºC

COO CH2 CH2

b) PET functionalization by aminolysis using ethylenediamine: CH2 CH2 COO

COO

CO

CH2 CH2 OOC

CH2 CH2 OOC

NH

+NH

COO CH2 CH2

CH2 CH2 NH2 + HO

2

CH2 CH2 NH2 24h / 20ºC

CH2 CH2 OOC

COO CH2 CH2

This result is in agreement with the data presented in the literature [110, 111]. c) PET functionalization by treatments of saponification and aminolysis performed simultaneously: + NaOH

CH2

COO

CH2

COO

COO

CH2

CH2

COONa + NH2 CH2

OOC

CH2 NH

COO

OC

CH2

CH2

CO NH

+ NH2

CH2 CH2

NH2

24 h / 20 ºC CH2 CH2 NH2 + HO

CH2

CH2

OH

252  Frontiers of Textile Materials d) PET functionalization by two treatments (saponification and aminolysis) performed individually, after 24 h: CH2

CH2

COO

CH2 CH2 OOC CH2 CH2 CH2 CH2

OOC

OOC

COO

COONa + HO

CH2 CH2 OOC

COONa + HCl

COOH +NH2 CH2 CH2 NH2

20 ºC 15 min. 20ºC / 24h -H2O

+NaOH

COO CH2 CH2

CH2 CH2 OOC

COO CH2 CH2 COOH + NaCl

CH2 CH2 OOC

CH2 CH2 OOC

24 h / 20ºC

CO

NH CH2 CH2

NH2

The chemical changes of PET by treatment with NaOH ± ethylenediamine were confirmed by the results of a spectroscopic analysis (FTIR) and a tinctorial one (Figure 11.10). FTIR spectra in Figure 11.10a and b indicates changes to the new functional groups: a) COOH groups: at 1709, 1236, 1092, and 1016 cm−1 corresponding to C=O stretching and C–O stretching [112–114]). The OH group is visible between 2500 and 3300 cm−1; (O–H stretching, very broad). The saponification treatment affects the length of the C−C chain, decreasing it the most (very small peaks within the range 2931−2838 cm−1). b) OH groups: at 3311 cm−1 (OH stretching), and 1406 cm−1 (for OH band); c) NH2 groups: around 1548 cm−1 (NH2 stretching, primary amines have two bands), between 1338−1089 cm−1 for C−N stretching and between 3300 and 3500 cm−1 for N–H stretching (primary amines have two bands). The presence of the amide groups is visible between 3311 and 3600 cm−1 (NH stretching overlap with OH stretching), 1668 cm−1 (shoulder for C=O stretching), and 1563 cm−1 (combination NH deformation and C−N stretching). The presence of new functional groups on chemically modified PET fiber causes the following effects: 1) wettability by measuring the contact angles and longitudinal wicking [115]; 2) the surface roughness of the pores effective diameter [116]; 3) printing with anionic dyes (effect assessed using color strength and fastness tests) [117];

Multifunctionalizations of Textile Materials  253

absorbance

(a) Recycled PET

5 4 3 2 1 4000

3500

3000

2500

2000 1500 Wavenumbers (cm–1)

1000

3000

2500

2000 1500 Wavenumbers (cm–1)

1000

absorbance

(b) Virgin PET

5 4 3 2 1 4000

3500

Figure 11.10  Spectra FTIR for recycled PET (a) and virgin PET (b) without treatment (1), after saponification (2), aminolysis (3), simultaneously saponification + aminolysis (4), and individual saponification and aminolysis, after 24 h (5).

4) inkjet printing [118]. 5) dyeing with non-specific dyes (cationic and anionic) [96]

11.5.1.1 Dyeing of PET Functionalized with Agents Having Basic Character The PET functionalized with basic reagents may be dyed with disperse dyes but the K/S is lower than that of non-functionalized fibers [96]; this fact confirms the effect of functionalization by the lack of affinity of the newly introduced functional groups toward the disperse dyes (Figure 11.11).

254  Frontiers of Textile Materials NH2

H C

O

H C

HC

CH

H3C

N

C H

N

S S

N

S

CH3

O

Foron Brilliant S-GL (C.I. Disperse Red 121)

C H

N

CH3 CI

CH3

X H2O

Methylene Blue (C.I. Basic Blue 9)

Na+O–

Br

O

Br O–Na+

O

O Br

Br

Eosin Y (C.I. Acid Red 87)

Figure 11.11  Chemical structures of dyes used for functionalized PET dyeing.

The newly introduced COOH, OH and NH2 functional groups have affinity for cationic dyes (C.I. Basic Blue 9) and anionic (C.I. Acid Red 87). Changes generated by saponification (COOH groups) are highlighted by the high K/S values obtained with dyeing with a cationic dye. The presence of NH2 groups (derived from PET aminolysis) makes possible the dyeing with anionic dyes. The presence of two new types of groups (COOH and NH2) will result in more intense dyeing with the dye class specific to the predominant group. The discontinuous dyeing of the functionalized PET fibers is due to the following types of bonding: • electrostatic links between the new functional group COO− and the positive group in the cationic dye; the dyeing conditions are the following: 4% cationic dye (C.I. Basic Blue 9), 1% acetic acid, 125°C for 60 min. After dyeing the samples were 15 min soaped with 2 g/L nonionic surfactant at 60°C, then hot and cold rinsing and drying at room temperature; • links of hydrogen between the new OH polar groups introduced by functionalization, and the polar groups of the cationic and anionic dyes, respectively, non-polar links (van der Waals type) between non-polar groups of the dyes and the PET fiber.

Multifunctionalizations of Textile Materials  255 As expected, the functionalized samples with a mixture of NaOH and ethylenediamine led to the formation of several functional groups: COOH and NH2. The dyeing with C.I. Basic Blue 9 of these functionalized PET fibers reached the following luminosity values [96]: a) L* = 33.98 on recycled PET and functionalized with NaOH compared to L* = 44.25 on virgin PET but functionalized under the same conditions as PET recycled; b) L* = 31.57 on recycled PET and functionalized with NaOH + ethylenediamine (simultaneous process) compared to L* = 37.59 on virgin PET but functionalized under the same conditions. The dyeing with acid dye (C.I. Acid Red 87) led to lower values of luminosity on the samples treated with ethylenediamine solutions of 2M concentration; they are followed by those treated simultaneously with NaOH + ethylenediamine and then by those treated separately with NaOH and ethylenediamine. This fact confirmed that the number of NH2 groups formed during functionalization was higher when the functionalization was achieved with ethylenediamine solutions of 2 M concentration. The values of lightness difference (dL*) are shown in Table 11.5.

11.5.2 PET Functionalization with Alcohols Recycled and virgin PET fibers have been functionalized with three alcohols: ethanol, tetrol, and polyvinyl alcohol (PVA) [108]. The used tetrol (Tetronic 701) is in fact ethylenediamide tetrakis (ethoxylate-block-­ propoxylate) (Figure 11.12). The functionalization of PET with the three alcohols (ethanol, tetrol, and PVA) having two, four, or many OH groups was performed on a pre-functionalized PET support by saponification. It is known that PET saponification with NaOH is more effective if an alcohol (methanol) is added to the reaction medium. However, if an alcohol with a higher molecular weight than methanol (ethanol, tetrol, PVA) is added to the reaction medium, takes place a saponification reaction that is less effective. If a catalyst (NaH2PO2 or MgCl2) is added with NaOH and alcohol (ethanol tetrol, PVA), then the alcohol becomes a grafting agent on the saponified PET, regardless of the working temperature but respecting a suitable time (20°C storage 24 ÷ 48 h or 160°C, 3 min). In fact, in the first stage saponification occurs (PET enrichment with OH and COONa groups), then, in the presence of an alcohol and an acid catalyst, polycondensation reactions occur

b

a

V V V V R R R R

Saponification

Aminolysis

Saponification + aminolysis (simultaneous)

Saponification + aminolysis (individually, after 24 h)

Saponification

Aminolysis

Saponification + aminolysis (simultaneous)

Saponification + aminolysis (individually, after 24 h)

0.357

5.927

−39.248 3.654

2.704 0.577 0.073

NH2, HO NH2

COOH, NH2

7.525

0.281

COOH, HO

NH2

−36.844

−33.849

1.495

COOH, NH2

3.168

3.597

NH2, HO

−27.176

Cationic dye

3.115

Disperse dye

COOH, HO

Functional groupsa

Groups appeared after the treatment with NaOH ± ethylenediamine or ethylenediamine. Lightness difference (dL*) rule: the smaller than zero is dL*, the darker is the sample.

PET Virgin (V) Recycled (R)

Functionalization treatment

−4.182

0.329

−5.627

4.651

0.022

−4.918

−3.228

0.447

Anionic dye

Lightness difference (dL*)b

Table 11.5  The values of lightness difference (dL*) for virgin/recycled PET samples dyed (at 125°C, 60 min) with disperse, cationic, and anionic dyes.

256  Frontiers of Textile Materials

Multifunctionalizations of Textile Materials  257 R R

R N CH2

CH2

N

CH3 where R is

R

CH2

CH2

O

CH2

CH

O

CH

H y

x

CH2

n

OH

Tetronic 701

PVA

Figure 11.12  The chemical structures of the polyols.

which lead to the formation of ether bridges between the saponified PET and the alcohol used. The chemical changes generated by these alcohols were highlighted by spectroscopic (FTIR, EDAX and XRD), calorimetric (DSC), thermogravimetric (TGA, DTG), and colorimetric analyses [108]. The SEM images in Figure 11.13 clearly indicate that PVA is attached to both virgin PET and recycled PET. The XRD, TGA, and DTG spectra indicate that PVA functionality results in changes in the internal PET structure, stability, and behavior during burning. The DSC and DTG curves of PET samples treated with PVA have an endothermic peak in the temperature range 25°–135°C, the size of which indicates the ability of the sample to absorb moisture; water enters either the amorphous areas of treated PET fiber or forms hydrogen bonds with the new functional groups of treated PET (polar OH groups) introduced by PVA grafting (Figure 11.14). The size of the alcohols and especially the number of hydroxyl groups have influenced the tinctorial capacity.

11.5.2.1 Multifunctionalized PET Dyeing with Alcohols The dyeing of polyfunctionalized PET [108] was performed under the conditions shown in the Table 11.6. After dyeing all samples were dried at room temperature. (a) PVA grafted on virgin PET

HV MAG WD DET MODE PRESSURE HFW TEMP 10 µM 5.00 KV 3000 X 14.9 MM LFD SE 6.00E1 PA 99.5 µM QUANTA 200 3D

(b) PVA grafted on recycled PET

HV 10.00 KV

Figure 11.13  SEM images of PVA grafted on PET.

MAG 3000 X

WD 15.0 MM

DET LFD

MODE SE

PRESSURE 6.00E1 PA

HFW 99.5 µM

TEMP

10 µM QUANTA 200 3D

258  Frontiers of Textile Materials (b) TGA

PET V PET R PET V + PVA PET R + PVA

600

Weight loss (%)

Internity1G [ Count1G]

(a) XRD

400

80 60 40 20 0

200 200

400 600 2-Theta [degree]

(d) DTG

PET V

PET R

PET V + PVA

PET R + PVA

0 –1 –2 –3 –4 –5

0.01 0 –0.01 –0.02 –0.03 –0.04 –0.05 –0.06 –0.07 –0.08 –0.09 –0.1

0

100 200 300 Temperature (ºC)

400

500 Temperature (ºC)

1000

PET V

l/ºC)

Heat Flow (mW)

1

0

800

(c) DSC

PET V PET R PET V + PVA PET R + PVA

120 100

PET R PET V + PVA PET R + PVA 0

200

400 600 800 Temperature (ºC)

1000

Figure 11.14  Results of different analyses: XRD (a), TGA (b), DSC (c), and DTG (d).

The dyeing with direct dye is influenced by the following conditions: • The presence of ethanol in the saponification bath (without catalyst) leads to more intense color than the samples saponified only with NaOH, as it is likely to cause a stronger saponification; • The hypophosphite type catalyst in the NaOH and ethanol treatment bath attributes to ethanol a role of grafting agent (when working at T = 20 °C; t = 48 h) attaching it to the macromolecular chain of saponified PET, by means an etheric bond; • The dyeing with direct dye can be explained on the basis of H bonds occurring between OH groups of saponified PET and OH, NH2 and SO3− groups of the dye; • The presence of a polyfunctional alcohol (tetrol) in the treatment bath does not improve the degree of saponification of PET so it does not function as a co-saponification agent because leads to weaker K/S than the saponified PET; • All PVA multifunctional samples are less bright after dyeing, so they have been dyed more intensely than those

Multifunctionalizations of Textile Materials  259 Table 11.6  Dyeing protocol. Dyeing recipe

Dye’s name in color Index

Final stages of dyeing

3% owf* direct dye 10% owf NaCl M = 100:1 T = 100°C t = 1h

C.I. Direct Red 13

1) Rinsing 2) Warm washing 3) Cold washing

3% owf acid dye M = 100:1 T = 100°C t=1h

C.I. Acid Red 87

1) Rinsing 2) Warm washing 3) Cold washing

3% owf vat dye 5 g/L NaOH 3 g/L Na2S2O4 M = 100:1 T = 20°C; t = 1 h

C.I. Vat Orange 11

1) Oxidation at 40°C:1.5 mL/L H2O2 35%; 1 mL/L CH3COOH 2) Warm washing 3) Cold washing

3% owf reactive dye pH=10 (Na2CO3) M = 100:1 T = 60°C t=1h

C.I. Reactive Blue 38

1) Rinsing 2) Hot soaping: 1 g/L surface active agent; M = 50:1 3) Warm washing 4) Cold washing

*% owf means percent on weight of fabric.

functionalized with NaOH only (have dL* < 0). This can be explained by the large number of polar functional groups (OH) attached to the new PET support, coming from PVA; these groups may form polar hydrogen bonds with direct dyes making it possible to dye them more intensely; The dyeing with acid dye of the PET treated with NaOH + ethanol + catalyst leads to good K/S and big differences comparative of the saponified sample (dL* = −10) due to probably hydrogen bonding between the two partners. Dyeing with vat dyes: All virgin and recycled PET samples treated with NaOH + ethanol + catalyst are dyed more intensely than standard virgin PET, having the brightness difference dL * < 0 (dL * = −2 to −5). The explanation is based on the fact that by saponification, holes, microfishes appear in the textile support so all samples become more accessible for

260  Frontiers of Textile Materials the insoluble dye molecules; by means of the alkaline reducer, the dye molecules will solubilize and develop, dyeing textile support, and after the oxidation step they will convert into the initial, insoluble form. Dyeing with reactive dyes results in dL* > 0, so all functionalized PET samples are dyed less than the virgin PET standard.

11.5.3 PET-Multifunctionalization with MCT-β-CD The permanent MCT-β-CD grafting on PET supports is possible through alkali agents that act as saponification agents and create reactive OH groups capable of binding the MCT-β-CD molecules via the chlorine atom in the triazine cycle [109]. Grafting efficiency depends on the grafting conditions (temperature, duration, catalyst, grafting agent concentration) and saponification efficiency. The grafting reaction takes place according to the chemical reactions presented in Figure 11.15. The presence of MCT-β-CD determines the increase of PET reactivity due to the new functional groups introduces: – Cl which has affinity for reactive dyes; – OH from β-cyclodextrin having affinity for anionic dyes. It is necessary a compromise between the breaking resistance of the PET supports and the water absorption capacity, this balance being able to be changed to the needs of the user. The temperature and the treatment time can be chosen according to the destination to be received by the PET support as follows: if it is intended to have low air permeability, higher water absorption, and breaking strength lower than untreated PET then the treatments

PET’ − COO – PET’

NaOH saponification treatment

+

PET’ - COONa

HO - PET’

PET grafting treatment

CI − T-β – CD MCT-β-CD

PET’

-O-

T − β – CD

MCT-β-CD grafted on PET

Figure 11.15  Scheme of grafting MCT-β-CD on PET.

Multifunctionalizations of Textile Materials  261 should be at 130°C. Instead, if it is intended to have increased resistance to PET fiber, less roughness, the treatments should be chosen at 20°C.

11.5.4 Functionalization of the PET Surface with Plasma Treatment PET is a synthetic polymer with good mechanical properties but with a pronounced hydrophobicity and low reactivity. For these reasons, it is often subjected to physical treatments (plasma treatments) or chemical (grafting) to functionalize and improve wettability and reactivity. Literature indicates research in which PET is functionalized by completing physical treatments with graft-type chemical treatments. Thus, the PET was grafted with maleic acid [119, 120] or with PVA, thus maintaining the mechanical properties and a good wettability appreciated by the low contact angles [117, 121]. By exposing PET to dielectric barrier discharge (DBD) plasma in air at atmospheric pressure under ambient conditions, surface and chemical changes occur. The chemical modification of the outer layers was proven by the formation of new polar groups (usually COOH and OH) due to the plasma-generated process (cleavage of the ester bond from PET). The physical changes of the surface are much more intense and produce noticeable damage through the appearance of a significant amount of surface roughening. Changes to topography have a greater influence on wettability, characterized by contact angle and free surface energy. The degree of change to the surface topography is dependent on both the discharge power used and the number of treatment cycles. After 20 cycles of processing in air at 500 W or 1000 W, surface topography changes insignificantly; only after 50 cycles changes are important [122, 123]. Plasma treatment of synthetic materials is usually done to reduce their hydrophobicity and to increase their adhesion to certain product rich in polar groups. Other uses of cold plasma are the initiation/facilitation of grafting [124] on natural polysaccharide polymers [125] in a dry environment. Literature [106] shows the effects of a technology based on the functionalization of PET surface in a dry environment (plasma) followed by multifunctionalization grafting performed in a wet environment (by a pad-dry-cure technology). Plasma treatment was performed on a COATING STAR DBD (dielect­ ric barrier discharge), manufactured by Ahlbrandt System in Germany. The textile material passed between the two electrodes (0.5 m long and 1.5 mm distance) two times (with each face of the material facing the electrodes).

262  Frontiers of Textile Materials During plasma pre-treatments, the fabric samples are in contact with the counter electrode and pass through the plasma gas present between the electrodes and the counter-electrode gap with the 2 m/min passage speed [126]. The parameters of the appliance were kept constant, namely: 750 W total electric power supplied by electrodes, an electrical voltage of 15 kV, a frequency of 26 kHz. After plasma pretreatment, materials need time to relax the free surface energy (2 days). The main mechanism to explain the relaxation phenomenon suggests that the polar groups created on the surface of the modified material migrate (over time) for the most part and thus they no longer influence the free surface energy because they are now below the outer layer of the surface [122]. After the relaxation step, the textile materials were chemically treated for grafting with a polyfunctional compound using pad-dry-cure technology. The grafting agents used are: a tetrol known as Tetronic 701, chitosan and MCT-β-CD. Each grafting agent was applied by a pad-dry-cure technology. For impregnation, 75–150 g/L reagents + 25 g/L catalyst (MgCl2 and, respectively, Na2CO3 in the case of MCT-β-CD) were used for the following operations: drying (3 min at 120°C) and curing (3 min at 160°C). In all cases studied, plasma treatment determines the functionalization of the PET supports by the appearance of the polar groups (COOH and OH), facilitating grafting. These groups originate from the cleavage of some ester linkages from PET. In fact, the cleavages of the ester linkages which there are on the surface of PET lead to radicals that react with the radicals present in the plasma gas and generate hydroxyl or COOH groups [127, 128]. The larger number of polar groups leads to smaller contact angles. The contact angles are smaller when the treatment time and the discharge power density are higher [129]. The scheme of the mechanism underlying the treatments applied to the PET supports [106] is shown in Figure 11.16. The COOH and OH groups (from plasma-treated PET supports) were covalent linked (via ester/ether links) with the OH (from Tetronic 701 or chitosan) groups, in the presence of catalysts, reactions that occurred during the condensation stages of pad-dry-cure technologies. In the case of MCT-β-CD, ester/ether linkages were formed between the triazine cycle (chlorine atom having been substituted) and the COOH or OH groups of the PET support. It is not excluded either the interaction between reagents that can generate partial networks at the surface of the material with the formation of ether bridges. Changes generated at the surface of textile supports were highlighted by SEM (Figure 11.17) and FTIR-ATR analyses [106].

COOH OH HO

PET

HOOC HO

OH COOH

OH

+ Tetronic 701

HO

COOH OH O OH

O

Grafting 1 HO

HOOC O OH

HO

Functionalized PET

OH

HO

COO

OH OH

OH

Plasma treatment

COOH

OH

Multifunctionalizations of Textile Materials  263

O COOH OH

OH

Multifunctionalized PET + Chitosan Grafting 2

NH2

CI

O

NH2

COO

HOOC O O NH2 O

HO

OH

NH2

O

O COOH OH O

OH OH NH2

CI

NH2

NH2

MCT-β-CD Grafting 3

O

HO HO

OH

O

O

NH2

NH2 O

Multifunctionalized PET

HO

COO

HOOC O O

HO

OH COOH O NH2 O O OH O

OH

OH

O

O

OH

HO

CI

OH

O

OH COOH O NH2 CI O O O O

OH

OH

NH2

NH2

O

O COOH OH O

OH OH NH2 OH

Multifunctionalized PET

Figure 11.16  Scheme of PET multifunctionation by plasma pretreatment followed by three grafting processes with polyfunctional compounds. (a) Control PET

mag WD det mode pressure HFW temp HV SE 6.00E1 Pa 59.7 µm 20.00 kV 5000 x 14.3 mm LFD

(b) PET pretreated with plasma

10 µm Quanta 200 3D

(c) Tetronic 701 grafted on PET

mµ 02 pmet WFH D3 002 atnauQ mµ 911

erusserp edom ted DW gam VH aP 1E00.6 ES DFL mm 6.41 x 0052 Vk 00.02

HV 20.00 kV

mag 20000 x

WD 9.7 mm

det LFD

mode SE

(d) Tetronic 701 + chitosan grafted on PET

20 µm HV mag WD det mode pressure HFW temp Quanta 200 3D 20.00 kV 2500 x 14.6 mm LFD SE 6.00E1 Pa 119 µm

pressure 5.96E1 Pa

HFW 14.9 µm

temp

2 µm Quanta 200 3D

(e) Tetronic 701 + chitosan + MCT-β-CD grafted on PET

20 µm HV mag WD det mode pressure HFW temp 20.00 kV 2500 x 14.6 mm LFD SE 6.00E1 Pa 119 µm Quanta 200 3D

Figure 11.17  Morphological aspects of multifunctionalized samples by plasma treatment ± grafting with polyfunctional reagents.

264  Frontiers of Textile Materials Although air atmospheric-plasma pretreatment has altered the morphology of the surface, however, there is only one change, confirmed by the FTIR analysis: the presence of COOH groups (at 1730, 1236–1016 cm−1) and OH (at 1236–1016 cm–1) as a result of the dissociation of ester groups from PET under the action of electric discharge during plasma treatment. Grafting of polyfunctional compounds was confirmed by: • at high concentrations, Tetronic 701 was grafted onto the PET, evidenced by the appearance of a peak of 2970 cm−1 (metoxy group), 907 cm−1 (C-skeletal from the metoxy group), and 1238 cm−1 (ethoxy group); • chitosan grafting on the OH groups of the plasma functionalized PET is confirmed by the 1016 and 1175 cm–1 (C–O–C asymmetric and symmetric stretch) peak heights; • the presence of MCT-β-CD on the final samples is confirmed by the increase of all the peaks but the most obvious increase occurs in the range 2928–2850 cm–1 (CH2 stretchings), and 1502 cm–1 (C=N of the triazine group of MCT). The change in peak height from 1016 cm–1 confirms the formation of the ether bonds with PET. The higher height of the peak at 1712 cm–1 leads to the hypothesis of the formation of the ester bonds between COOH groups of the plasma-functionalized PET and the chlorine atom bound to the triazine cycle of MCT-β-CD. The effects of the treatments are confirmed by the following values [106]: • High values for take-off values (2.87–3.01%); • Smaller contact angle values (75.03° for PET grafted with polyfunctional compounds compared to 105.21° for untreated PET); • Large values for wrinkle recovery angles (238°–261° versus 200° for untreated PET), • Durability of treatments (plasma + grafting/multi-functionalization) is tested by dyeability and color measurements.

11.5.4.1 Dyeing of PET Functionalized by Means of Plasma and Grafting with Polyfunctional Compounds C.I. Acid Blue 220 dye used to highlight the durability of the linkages created during grafting and a good dyeability [106]; it has the chemical structure shown in Figure 11.18.

Multifunctionalizations of Textile Materials  265 O

NH2

O S

O–Na+ O CH3

O

HN

H3C

CH3

Figure 11.18  Chemical structure of C.I. Acid Blue 220 dye.

The durability of the treatments was highlighted by colorimetric measurements. Transformations generated by plasma pretreatments and grafting treatments make it possible to dye textile supports with an acid dye, not specific to them. The fact that the dyeing can be achieved, that it is uniform and penetrated proves the durability/strength of the connections made between the polar groups resulting from plasma pretreatment (COOH and OH groups in the case of PET) and those from the agents used in the grafting (OH or NH2 groups) even under severe conditions of dyeing (100°C, 90 min). It is known that the large kinetic energy developed during the dyeing process can cause loose, superficial bonding. The results of the dyeing confirm that all pretreated plasma samples have K/S values higher than those of the control samples at 630 nm (where the blue color absorption is maximum) (Figure 11.19). There are ionic interactions between the treated textile fabrics and the dye (with +NH3 groups obtained during protonation at the beginning of the dyeing). Also, the linkages between the treated support and the dye may be: hydrogen (between polar groups) or electrostatic type established between the cationic groups of chitosan (+NH3 groups obtained during the protonation step) and the anionic groups of the dye SO3− . In the protonation step, it is possible to protonate not only the amine groups of already grafted chitosan but also some of the NH2 groups in the dye; At the end of dyeing, the following values of the colorimetric measurements (Figure 11.19a) were obtained on the PET functionalized with plasma and grafted with polyfunctional compounds:

(

)

• K/S = 0.26 for PET functionalized with plasma; • K/S = 1.5–2.7 for PET functionalized with plasma and grafted with polyfunctional compounds; • K/S = 0.11 for untreated PET.

266  Frontiers of Textile Materials 3 2.5

(a) PET

W 1

K/S

2

2

1.5

3

1

4

0.5 0 350 6

450

550 Wavenumber (nm)

650

(b) PET/cotton

W

5

1

4 K/S

750

2

3

3

2

4

1 0 350

450

550 Wavenumber (nm)

650

750

Figure 11.19  K/S values for PET 100% (a) and PET/cotton (50/50%) (b) grafted with Tetronic 701 + chitosan + MCT-β-CD (in different concentrations) and then dyed with C.I. Acid Blue 220: control sample/with plasma pretreatment but without grafting (W), grafting with maxim concentration of Tetronic 701 (1), grafting with maxim concentration of chitosan (2), grafting with maxim concentration of MCTβ-CD (3), and grafting with average concentrations of Tetronic 701, chitosan, and MCT-β-CD (4).

If the fabric is mixed (PET and cotton) then K/S values are higher than PET 100% (Figure 11.19b).

11.6 Cotton: Multifunctionalization Ways The cotton materials can be multifunctionalized by the following ways: 1) plasma surface activation followed by grafting with polyfunctional compounds [106]; 2) grafting with alkyl chitosan [130–132];

Multifunctionalizations of Textile Materials  267 3) crosslinking/grafting with polyfunctional compounds: Tetronic 701 (a tetrol) + chitosan [133], Tetronic 701 + MCT-β-CD [134], Tetronic 701 + chitosan + MCT-β-CD [135], carbonyl compounds ethylenediamine + MCT-β-CD [136–138].

11.6.1 Surface Activation with Plasma Followed by Grafting with Polyfunctional Compounds Physical stimuli (plasma) modify the morphological aspect and the crystalline–amorphous ratios of the natural/synthetic polymers. The ­ reactivities of these polymers are sufficient to interact with polyfunctional grafting agents (Tetronic 701, chitosan, MCT-β-CD), thus leading to the multifunctionalization of treated fabrics, evidenced by obtaining multiple effects (sometimes even contradictory): hydrophilicity + crease resistance + antibacterial capacity [106]. Grafting was type “graft on graft” and was achieved by applying three times of “pad-dry-cure” technology; 25–50 g/L reagents + catalysts (25 g/L MgCl2 and 30 g/L Na2 CO3 in the case of MCT-β-CD) were used for impregnation. The other operations were performed under the following conditions: drying (3 min at 120°C) and curing (3 min at 160°C) [106]. The multifunctionalizations may be highlighted by spectroscopy analyses, and colorimetric. The FTIR spectrum of the cotton sample pretreated with plasma differs from that of the untreated sample by an absorption around 1743 cm−1 (Figure 11.20). This is attributed to the formation of carbonyl (C=O) from aldehyde (CHO) and acid (COOH) groups as a result of the effects of electric discharge on the surface of cotton samples. Other cellulose-specific adsorption (OH– groups and β-glucoside linkages) do not change because plasma pretreatment acts only on the surface of the material, at a depth of only 1–10 nm; so, the polymer is not attacked in depth which results in the unchanged maintenance of properties in the material volume. These statements are consistent with the data present in literature [106, 128]. The three pad-dry-cure processes lead to a series of changes proving the presence of the three grafting agents (Tetronic 701, chitosan, and MCTβ-CD) [106]. Due to the catalyst and high temperature in the polycondensation stage (160°C), in the final sample were formed ether/ester groups between cellulose and each of the three agents used in grafting. The formation of the ether bonds is confirmed by the higher height of the peaks at

3000

1203 1157 1107 1051 1026 1203 1159 1107 1053 1029 -

1629 1535 -

-Untreated cotton

3500

1203 1161 1107 1053 1029 -

1629 -

1743 -

2920 2850 - Cotton + plasma treatment

2920 2850 -

% transmittance

- Cotton+ plasma + grafting treatments

1535 -

2920 2350 -

1741 1629 1603 1565 1535 -

268  Frontiers of Textile Materials

2500

2000

1800

1600

1400

1200

Wavenumbers [1/cm]

1000

800

600

Figure 11.20  FTIR spectra for multifunctionalized cotton sample.

1203 and 1026 cm−1 that are attributed to asymmetrical and symmetrical C–O–C stretchings. The formation of the ester linkages is evidenced by the 1741 cm–1 (C=O stretching) peaks, 1245 cm–1 (for C–O–C stretching vibration) and 1626 cm–1 (for C=O asymmetric stretching). This last peak has a higher height because it is the result of the overlap with the absorption of the water absorbed by the final sample, which means a better hydrophilicity of the final sample. The presence of each grafting agent in the final sample is confirmed by the appearance and/or height increase of specific peaks: 3010 and 1278–1246 cm−1 from Tetronic 701, 1535 cm−1 from chitosan and 1603 and 1566 cm−1 from MCT-β-CD. The increase of the peaks in the 2920–2850 cm−1 range correspond to the CH2 asymmetrical and symmetrical stretching and confirms the increase of the C–C chain due to grafting. Therefore, plasma treatments did not bring about major changes in the chemical structure of cotton: only carbonyl groups (C=O of aldehyde type) and acidic groups (COOH at 1743 cm−1) due to the effects due to the action of electric discharge on the surface of cotton. COOH groups have a high affinity for water. Hydrophilization is facilitated by numerous physical changes, the appearance of increased roughness. The gaps created between these bumps can accumulate plenty of water. Polyfunctional grafting (Tetronic 701, chitosan and MCT-β-CD, confirmed by FTIR analysis)

Multifunctionalizations of Textile Materials  269 on plasma pretreated supports increases the number of polar groups and leads to the smallest water contact angles (54°–56°) therefore to the best hydrophilic effects. By chitosan and MCT-β-CD grafting on cotton improves the ability of cotton to resist at the creases formation; the wrinkle recovery angles are between 192° and 250°. The take-up values of polyfunctional agents on samples pretreated with plasma were 6.34% to 7.59%, while on the samples untreated with plasma but grafted with Tetronic 701 + chitosan + MCTβ-CD the values were between 4.15% and 6.20%. Following these treatments, multiple effects (sometimes even contradictory) can be obtained: hydrophilicity + crease resistance and antibacterial capacity if it is considered that chitosan has a pronounced antibacterial character.

11.6.1.1 Dyeing of Multifunctionalized Cotton by Plasma and Grafting Treatments A non-conventional dyeing using non-specific dyes for raw cellulosic material, but specific for the multifunctionalized material is simpler and efficient, in this case. Multifunctionalized cotton can be dyed with acid dye (C.I. Acid Blue 220) (Figure 11.21). In Figure 11.21a and b, the K/S values (in the 550–650 nm range where blue color absorption is maximum) were as follows: • K/S = 1 for plasma-functionalized cotton only compared to K/S = 0.5 for non-plasma-functionalized cotton; • K/S = 4–6 for plasma functionalized cotton and grafted with polyfunctional compounds, depending on their concentration; • K/S = 3.5–4.5 for untreated plasma but grafted with the polyfunctional agents mentioned.

11.6.2 Alkyl Chitosan Grafting on Cotton The first alkyl chitosan was synthesized by Muzarelli [139], and the product was used in the medical field with an antibacterial character due to the presence of the positive charge of the N atom. In time, other researchers synthesized the alkyl chitosan through various methods, as follows: reductive alkylation; Michael addition and direct alkylation [140]. The reductive method is based on the following step for obtaining the alkyl chitosan (Figure 11.22):

K/S

270  Frontiers of Textile Materials 5 (a) cotton without plasma 4.5 treatment 4 3.5 3 2.5 2 1.5 1 0.5 0 350 450 550 Wavenumber (nm) 7 6

W 1 2 3 4

650

(b) cotton with plasma treatment

W 1

5 K/S

750

2

4

3

3

4

2 1 0

350

450

550 Wavenumber (nm)

650

750

Figure 11.21  K/S values for cotton grafted with Tetronic 701 + chitosan + MCT-β-CD (in different concentrations) and then dyed with C.I. Acid Blue 220: control sample/without grafting (W), grafting with maxim concentration of Tetronic 701 (1), grafting with maxim concentration of chitosan (2), grafting with maxim concentration of MCT-β-CD (3) and grafting with average concentrations of Tetronic 701, chitosan and MCT-β-CD (4).

• reduction of the amine group of chitosan with an aldehyde; a Schiff base is formed; • reduction of the Schiff base with a reducing agent (NaBH4, as a rule); • formation of the quaternary salt at the level of the N atom from chitosan, i.e., formation of trialkyl chitosan from the reaction of monoalkyl chitosan with an alkylation agent type R–I iodide, in the presence of NaOH and NaI. If the alkylation agent R–I was methyl iodide, then the process also includes an “ion exchange”-type stage, in which the iodine ion is replaced by chlorine. Though extremely efficient, the methyl iodide is easily volatile and dangerous for human health, since it is carcinogenic [139].

Multifunctionalizations of Textile Materials  271 HOH2C

CH3I RCHO

O

O

O

NH2

HOH2C O

reductive alkylation

O N

HO

HO

CHR Schi base

Chitosan

NaBH4 NaCN

O R'

HO

O

ion exchange

CH2R

O

HOH2C

NaOH/ NaI O

+N

reduction

R'I

O

HOH2C

O

O NHCH2R

R'

HO

Quaternized chitosan

N- alkyl chitosan

Figure 11.22  Diagram of the trialkyl chitosan production by reductive method.

Michael addition is based on the utilization of α, β- unsaturated compounds, such as acrylic acid, which reacts with the NH2 groups from chitosan [141]. Method of direct alkylation is based on two steps: • chitosan treatment with an iodide type alkylation agent. Reaction occurs under certain conditions of temperature and catalyst, at pH = 8.0 ÷ 8.5 realized with NaOH in presence of NaI and R–I (usually CH3I) as alkylation agent [142]. • ion exchange stage, when the ionic ion is replaced by chlorine (from a NaCl solution). The scheme of alkylation according to the direct alkylation method is given by the chemical reaction presented in Figure 11.23.

HOH2C

O

O

O direct alkylation NH2

HO

HOH2C

CH3I NaOH, NaI

HO

O

O

HOH2C

NaCl O

+ CH3 I- N CH3 CH3

O

ion exchange HO

O O

+ CH3 Cl- N CH CH3 3

Figure 11.23  Diagram of the trimethyl chitosan production by direct alkylation method.

272  Frontiers of Textile Materials Irrespective of the utilized alkylation method, the alkyl chitosans were used only in medicine field. However, literature suggests a way to obtain triethyl chitosan that can be used in the textile industry [130–132] because it can cause multiple effects: anti-wrinkle effects (wrinkle recovery angles = 152°–245°), hydrophobia (contact angles = 154°–168°), good breaking resistance and antimicrobial effects (against Micrococcus luteus and Escherichia coli). All these effects depend on the reaction conditions: molar ratio of chitosan: alkylating agent: NaOH, polycondensation temperature, type of catalyst [131, 132]. The sequence of steps leading to triethyl chitosan is the following [131]: • in situ obtaining of the alkylating agent: • obtaining alkyl chitosans by treating the solution of chitosan with alkylating agent and NaOH in certain molar ratios. The synthesis of alkyl chitosans (mono, di or triethyl chitosan) [131] is highly dependent on the molar ratio chitosan: alkylating agent: NaOH. Therefore, ANOVA was used as the statistical method of quantification of alkyl chitosan synthesis and their grafting effects on cotton. The higher the concentration of the alkylating agent, the higher the substitution capacity at the N level from chitosan is, thus increasing the alkylation capacity. Figure 11.24 shows the chemical reactions taking place at each stage. Triethyl chitosan grafting on cellulose from cotton is possible due to the high temperature (160°C) and the catalyst from the condensation stage of the pad-dry-cure technology (Figure 11.25). Analyses that confirmed the presence of alkyl chitosans on the cotton fabric were: FTIR, XPS, 1H-NMR, SEM, and DSC, TGA/DTG analyses indicated the amount of moisture and thermal stability. A simpler method of highlighting the presence of alkyl chitosans on cotton is the tinctorial method.

HCl+ CH3 CH2

OH

OH O

O HO

NH2

Chitosan powder

catalyst

+ CH3COOH

O

solving protonation

CH3 CH2

Cl + H2O OH O

O HO H3

O

N+

Dissolved/protonated chitosan

+ NaOH + ClC2H5

alkylation

OH O

O

+N

HO H5C2

O

-Cl

C2H5 C2H5

Chloride triethyl chitosan

Figure 11.24  Diagram of the triethyl chitosan production by direct alkylation method.

Multifunctionalizations of Textile Materials  273 O Cellulose

OH Cellulose OH

+

O

O +

O -Cl

N HO C2H5 H5C2 C2H5 Chloride triethyl chitosan

pad - dry - cure

O

O

curing/160 C (CH3COO)2Zn as catalyst

+

O -Cl

N HO C 2 H5 H 5C 2 C2H5

Cellulose partial cross-linked

Figure 11.25  Triethyl chitosan grafting on cellulose from cotton.

11.6.2.1 Dyeing of Cotton Grafted with Alkyl Chitosans The tinctorial method may indicate the presence of amine groups (with varying degrees of substitution) present in the alkyl chitosans grafted on cotton fabric [131]. It can also demonstrate the durability of the effects of alkyl chitosans grafting treatments with under the energetic conditions used in dyeing (T = 100°C, t = 60 min). For this purpose, non-specific dyeing colors are used: anionic dyes (acid dyes) and cationic dyes. In both cases, the dyeing is done in two steps: 1) keeping the fabric (for 15 min) in a solution of a certain pH: a) neutral pH (pH = 7) to show only substituted amino groups; b) acid pH (pH = 5) for the protonation of the free amine group from alkyl chitosans; 2) dyeing: adding dye to the dyebath (3%), raising the temperature to 100°C where it is maintained for 60 min. Cooling was followed at 70°C and then warm and then cold. Two dyes were used in dyeing and their chemical structures are presented in Figure 11.26a and b. The tinctorial behavior of the cotton samples grafted with alkyl chitosans is based on the nature of the interactions that occur between the substituted amine groups of alkyl chitosans and the ionic groups of the dyes: attraction interactions (Figure 11.27a because in the C.I. Acid Red 88 dye there are anionic groups of SO3− type) and rejection interactions, respectively (Figure 11.27b because there are groups with positive loads in the C.I. Basic Blue 9 dye). It is known that in the synthesis of alkyl chitosans, mixtures of monoethyl chitosan, diethyl chitosan and triethyl chitosan are actually obtained, but one of them is predominant according to the molar ratio chitosan: alkylating agent: NaOH used.

274  Frontiers of Textile Materials OH

N N

N

H3C

O S O

S

N

+

N

Cl

CH3

CH3

O–

(a) C.I. Acid Red 88 (C.I. 15620)

CH3

–

(b) C.I. Basic Blue 9 (C.I. 52015)

Figure 11.26  Chemical structures of dyes used in the dyeing of cotton grafted with alkyl chitosans.

(a) C.I. Acid Red 88 (at λ= 500 nm) 12

pH=5

pH=7

10

K/S

8 6 4 2 0

Control sample

Monoethyl chitosan

Triethyl chitosan

K/S

(b) C.I Basic Blue 9 (at λ= 600 nm) 9 pH=5 pH=7 8 7 6 5 4 3 2 1 0

Diethyl chitosan

Control sample

Monoethyl chitosan

Diethyl chitosan

Triethyl chitosan

Figure 11.27  K/S values after dyeing with C.I. Acid Red 88 (a) and C.I. Basic Blue 9 (b).

It results that the dyeing with acid dye in a neutral environment is possible due to the electrostatic attraction between the anion of the dye and the substituted amino groups in the alkyl chitosans (positively charged groups) leading to more pronounced K/S values than the control sample.

Multifunctionalizations of Textile Materials  275 In an acid environment, the K/S values are higher than in the neutral environment, in addition, the +NH3 groups appear from the protonation of the NH2 groups not involved in the alkylation. In the case of dyeing with a cationic dye, the K/S values are lower than in the control sample both in acid and neutral conditions. In both cases the dyeing takes place via the hydrogen bonds between the primary OH of the treated cotton and the N and S atoms of the cationic dye. It results that during dyeing there are rejecting forces between the positive amine groups of the alkylated cotton and the cations of the dye; rejection is lower when dyeing takes place in a neutral environment because only the positive amine groups involved in alkylation participate. When the dyeing takes place in an acid environment, the number of positive groups increases because all amine groups (free and alkylated by substitution) are protonated and the dye cations are rejected. The steric effect of substituted amine groups is also present.

11.6.3 Multifunctionalization of Cotton with Polyfunctional Compounds and Unconventional Dyeing Using polyfunctional agents, rich in polar groups, simultaneous effects of hydrophilicity and wrinkle proofing can be achieved. These agents can be applied to the fabric by successive pad-dry-cure technologies. Literature shows many ways of multifunctionalization of cotton, but few use the tinctorial method to prove the chemical changes in the cellulose, modifications generated by the functionalization treatment: 1) The functionalization of cotton with Tetronic 701 (a tetrol) and chitosan is confirmed by dyeing with an acid dye, Eosin Y (Acid Red 87, C.I. 45380) and a direct dye, Congo Red (C.I. 22120) [133]; 2) Functionalization of cotton with Tetronic 701and MCTβ-CD [134] is confirmed by C.I. Acid Blue 220; 3) Functionalization of cotton with Tetronic 701 + chitosan + MCT-β-CD [135] is confirmed by C.I. Acid Blue 220.

11.6.3.1 Functionalization of Cotton with Tetronic 701 and Chitosan In the first case, Tetronic 701 can be grafted onto cellulose by a covalent, ether bond: the primary OH groups of cellulose react with the terminal

276  Frontiers of Textile Materials OH groups from Tetronic 701, in the presence of the MgCl2 catalyst and at high condensation temperature (160°C) takes place the removal of a water molecule and the formation of an ether bridge type (Figure 11.28). Of course, it is also possible to attach chitosan directly to cellulose by means of an ether bridge. It can be noticed that between Tetronic 701 (already covalently bonded by cotton) and chitosan occur etheric bonds, more precisely between the terminal OH groups of Tetronic 701 and the primary OH groups of chitosan. This situation corresponds to grafting of chitosan on a graft (Tetronic 701) attached to cotton. The functional groups obtained from these treatments are OH (from Tetronic 701 which is a polyol, and chitosan) and NH2 from chitosan. Their presence is confirmed by dL* values after dyeing with direct dye and acid dye, respectively: • dL* between 0.3 to −3.6 in the case of Red Congo dyeing when hydrogen bonds are formed between treated cotton and dye; • dL* between −10.1 and −18.6 when Acid Red 87 lead to ionic bonds between the anion of the acid dye and the positive amine groups that form at the beginning of the dyeing in an acidic environment (pH = 4.5). The concentration of Tetronic 701 is very important because it has a double role: cotton cleaner and grafting agent. Tetronic 701 can act as a cleaning agent because is an amphoteric surface-active agent that contains both hydrophilic and lipophilic groups. Lipophilic groups have a high affinity for fats, oils, and wax that are in cotton. At higher concentrations, this tetrol can be attached via etheric bridges to the cellulose surface, due to the hydrophilic groups existing in its structure. Even though Tetronic 701 cleans cotton by increasing its wettability, the presence of chitosan increases hydrophobia but increases the ability of cotton to resist creases formation.

Cellulose

OH + OH Tetronic 701

MgCl2 OH 160ºC -H2O

Cellulose -O- Tetronic 701 OH + H2O 160ºC MgCl2 + HO

Cellulose O Tetronic 701

Chitosan

NH2

O Chitosan NH2 + H2O

Figure 11.28  Scheme for cotton multifunctionalized with a tetrol and chitosan.

Multifunctionalizations of Textile Materials  277

11.6.3.2 Functionalization of Cotton with a Tetrol (Tetronic 701) and MCT-β-CD The functionalization of cotton with Tetronic 701 and MCT-β-CD was presented in literature [134]. In Figure 11.29 is presented a scheme of cotton grafting scheme using 2 polyfunctional products, in 2 stage: 1) grafting with Tetronic 701; 2) grafting with MCT-β-CD. Of course, it is possible to attach MCT-β-CD directly onto cellulose via an ether bridge. Cotton so treated gets two simultaneous effects: wrinkle-resistance and wettability. The wrinkle-resistant effects of the treated samples are confirmed by the increased wet and dry wrinkle recovery angle values (200°–236°). The wettability of the treated samples is confirmed by smaller contact angles (about 58°) and higher capillarity (14–18 cm) compared to the untreated sample (12 cm). After dyeing with the acid dye, dL* values are obtained between –9 and –14, which confirms the chemical changes of the cotton during these treatments.

11.6.3.3 Successive Functionalization of Cotton with a Tetrol (Tetronic 701), Chitosan, and MCT-β-CD In this case, the functionalization of cotton consists in the successive treatment of cotton, by pad-dry-cure technologies, with Tetronic 701, chitosan and finally with MCT-β-CD [135]. The catalysts used in the first two steps are MgCl2 and for MCT-β-CD grafting is used Na2CO3. The scheme of cotton multifunctionalization is presented in Figure 11.30: It is not excluded to attach chitosan and MCT-β-CD directly to cellulose by means of etheric bridges. Multifunctionalized cellulose contains many OH groups (derived from Tetronic 701, chitosan and MCT-β-CD), free NH2 groups from chitosan and Cl atoms from the MCT reactive rings

Cellulose

OH + OH Tetronic 701

160ºC OH MgCl2 -H2O

Cellulose

O Tetronic 701

Cellulose 160ºC Na2CO3

O Tetronic 701

O

+ CI

MCT-β-CD

MCT-β-CD

Figure 11.29  Cotton functionalization with a tetrol and MCT-β-CD.

OH +H2O OH

OH +HCI

278  Frontiers of Textile Materials

Cellulose

OH

OH Tetronic 701

OH

MgCl2/160ºC (grafting 1)

Cellulose

HO

Chitosan NH2

Cl

MgCl2/160ºC

O Tetronic 701

(grafting 2)

O Chitosan NH

MCT-β-CD

OH

Na2CO3/160ºC (grafting 3)

MCT-β-CD

OH

Figure 11.30  Cotton multifunctionalization with Tetronic 701, chitosan, and MCT-β-CD.

attached to cyclodextrin. From the interaction of these groups with similar groups from the neighbor macromolecular chain of the multifunctionalized cellulose, networks are formed based on covalent bonds. So, there are phenomena of grafting and partial crosslinking. The high functionality due to the large number of polar groups (OH or NH2) also allows the formation of hydrogen bonds. This network based on covalent bonds favors the effects of anti-creasing, tear resistance and even water absorption capacity; water can easily penetrate into the gaps created by the network formed between the grafts. In this case, the multifunctionalized cotton can be dyed with the following dye classes: - Direct dyes due to the increase in the number of polar groups in the grafted cotton; - Acid dyes due to free NH2 groups of chitosan attached to cotton; - Reactive dyes due to Cl (from MCT ring) atoms and OH groups (from β-CD) not involved in grafting process.

11.6.4 Multifunctionalization of Cotton with Carbonyl Compounds and MCT-β-CD It is well known that carbonyl compounds have a good reactivity, which is why they have been used extensively in anti-creasing treatments of cotton. The first aldehyde, known for its good wrinkle proofing effects (from urea-formaldehyde derivatives) is formaldehyde. However, its toxicity required its replacement with other carbonyl compounds: glyoxal, acetone, octanal. In order to give cotton a wrinkle proofing ability and good wettability, it is advisable to use compounds with many polar groups, such as

Multifunctionalizations of Textile Materials  279 multifunctional derivatives, that proceed from the reaction of these carbonyl compounds with MCT-β-CD. In literature [136–138] the three carbonyl compounds (glyoxal, acetone and octanal) were used to synthesize multifunctional derivatives. The steps of synthesis of these derivatives were: a) Activation of carbonyl compounds in acidic/basic catalysis/ medium for 15 min as follows: 1) glyoxal/in acid catalysis; 2) (glyoxal + ethanol) in acid catalysis; 3) glyoxal + NH3; 4) acetone + ethylenediamine; 5) octanal in acid catalysis for 15 min; 6) octanal in acid catalysis for 5 min. b) Formation of the multifunctional derivative of activated carbonyl compounds and 20% MCT-β-CD, in the presence of NaOH as the catalyst, contact time 15 min. The multifunctional derivative obtained was then applied to the cotton sample using a pad-dry-cure technology. The squeezing of the material (squeezing degree = 80%) was followed by the drying (100°C, 3 min.) and condensation (160°C, 3 min). Finally, the samples were washed and dried at room temperature. In all cases, the wrinkle proofing effects were good: large wrinkle recovery angles (180°–210°) were obtained compared to untreated samples (168°). Although increased, wettability did not show very high increases due to the involvement of OH groups in the formation of networks between cellulose and the neighboring polyfunctional compounds.

11.7 Conclusions The functionalization of any synthetic/natural polymer is the way the polymer reactivity increases. The physical–chemical changes during functionalization treatment can be highlighted by various spectroscopic, calorimetric, thermogravimetric and tinctorial methods. Of these, the simplest/ easiest method to perform is the dyeing method: dyeing with dyes with affinity for the new functional groups is only possible if chemical changes have occurred in the functionalized fibers. The degree of functionalization is indicated by the magnitude of the color intensity, for which reason it is advisable for the tinctorial method to be used first to highlight the functionalization and then the research can be deepened using other more complex methods.

280  Frontiers of Textile Materials

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286  Frontiers of Textile Materials 92. Asakuma, Y., Nakagawa, K., Maeda, K., Fukui, K., Theoretical study of the transesterification reaction of polyethylene terephthalate under basic conditions. Polym. Degrad. Stab., 94, 240, 2009. 93. Ng, R., Zhang, X., Liu, N., Yang, S.T., Modification of nonwoven polyethylene terephthalate fibrous via NaOH hydrolysis: Effect on pore size, fiber diameter, cell seeding and proliferation. Process Biochem., 44, 992, 2009. 94. Kondratowicz, F.L. and Ukielski, R., Synthesis and hydrolytic degradation of poly(ethylene succinate) and poly(ethylene terephtalate) copolymers. Polym. Degrad. Stab., 94, 375, 2009. 95. Partini, M. and Pantani, R., FTIR analysis of hydrolysis in aliphatic polyesters. Polym. Degrad. Stab., 92, 1491, 2007. 96. Popescu, V., Muresan, A., Constandache, O., Lisa, G., Muresan, E.I., Munteanu, C., Sandu, I., Tinctorial response of recycled PET fibers to chemical modifications during saponification and aminolysis reactions. Ind. Eng. Chem. Res., 53, 16652, 2014. 97. Achwal, W.B., Use of cationic polymers as catalysts during deweighting of polyester by alkalies. Colorage, 73, 18, 1984. 98. Achwal, W.B., Comparative study of the surface action of caustic soda on polyester fabrics under different conditions. Man-made Text. India, 27, 185, 1984. 99. Nandy, D., Mishra, S.P., Thakker, J.H., Bhattacharya, S.D., An approach to improve aesthetic and comfort related properties of polyester fabric using sodium hydroxide and accelerator. Synth. Fibers, 28, 11, 1999. 100. Mittal, A., Soni, R.K., Dutt, K., Singh, S., Scanning electron microscopic study of hazardous waste flakes of polyethylene terephthalate (PET) by aminolysis and ammonolysis. J. Hazard. Mater., 178, 390, 2010. 101. Spychaj, T., Fabrycy, E., Spychaj, S., Kacperski, M., Aminolysis and aminoglycolysis of waste poly(ethylene terephthalate). J. Mater. Cycles Waste Manage., 3, 24, 2001. 102. Zhang, L.N., Liu, L.Z., Yue, Q.F., Zhu, C.C., From aminolysis product of PET waste to value-added products of polymer and assistants. Polym. Compos., 22, 13, 2014. 103. Esena, P., Riccardi, C., Zanini, S., Tontini, M., Poletti, G., Orsini, F., Surface modification of PET film by a DBD device at atmospheric pressure. Surf. Coat. Technol., 200, 664, 2005. 104. Hegemann, D., Brunner, H., Oehr, C., Plasma treatment of polymers to generate stable, hydrophobic surfaces. Plasm. Polym., 6, 221, 2001. 105. Tendero, C., Tixier, C., Tristant, P., Desmaison, J., Leprince, P., Atmospheric pressure plasma: A review. Spectrochim. Acta B, 61, 2, 2006. 106. Popescu, V., Sandu, I., Mureşan, E.I., Istrate, B., Lisa, G., Effects of the pre-treatment with atmospheric–air plasma comparative followed by conventional finishing. Rev. Chim.-Bucharest, 65, 676, 2014.

Multifunctionalizations of Textile Materials  287 107. Jasso, M., Hudec, I., Alexy, P., Kovacik, D., Krump, H., Grafting of maleic acid on the polyester fibers initiated by plasma at atmospheric pressure. Int. J. Adhes. Adhes., 26, 274, 2006. 108. Popescu, V., Sandu, I.C.A., Popescu, G., Lisa, G., Popa, A., Study of the effects by tinctorial method obtained at polyethylene terephtalate functionalization with alcohols. Rev. Chim.-Bucharest, 66, 1607, 2015. 109. Popescu, V., Muresan, E.I., Grigoriu, A.-M., Monochlorotriazinyl-beta cyclodextrin grafting onto polyester fabrics and films. Carbohyd. Polym., 86, 600, 2011. 110. Bendak, A. and El-Marsafi, S.M., Effects of chemical modifications on polyester fibers. J. Islamic Acad. Sci., 4, 275, 1991. 111. Hoang, C.N. and Dang, Y.H., Aminolysis of poly(ethylene terephthalate) waste with ethylenediamine and characterization of α, ω-diamine products. Polym. Degrad. Stab., 98, 697, 2013. 112. Bozaci, E., Arik, B., Demir, A., Oüzdoğan, E., Potential use of new methods for identification of hollow polyester fibers. Tekst. Konfeksiyon, 4, 317, 2012. 113. Krehula, L.K., Hrnjak-Murgić, Z., Jelenčić, J., Andričić, B., Evaluation of poly(ethylene-terephthalate) products of chemical recycling by differential scanning calorimetry. J. Polym. Environ., 17, 20, 2009. 114. Donelli, I., Freddi, G., Nierstrasz, V.A., Taddei, P., Surface structure and properties of poly-(ethylene terephthalate) hydrolyzed by alkali and cutinase. Polym. Degrad. Stab., 95, 1542, 2010. 115. Kan, C.W. and Yuen, C.W.M., Effect of atmospheric pressure plasma treatment on wettability and dryability of synthetic textile fibers. Surf. Coat. Tech., 228, S607, 2013. 116. Lazea, A., Kravets, L.I., Albu, B., Ghica, C., Dinescu, G., Modification of polyester track membranes by plasma treatments. Surf. Coat. Technol., 200, 529, 2005. 117. Salem, T., Pleul, D., Nitschke, M., Müller, M., Simon, F., Different ­plasma-based strategies to improve the interaction of anionic dyes with polyester fabrics surface. Appl. Surf. Sci., 264, 286, 2013. 118. Fang, K. and Zhang, C., Surface physical–morphological and chemical changes leading to performance enhancement of atmospheric pressure plasma treated polyester fabrics for inkjet printing. Appl. Surf. Sci., 255, 7561, 2009. 119. Jaššo, M., Hudec, I., Alexy, P., Kováčik, D., Krump, H., Grafting of maleic acid on the polyester fibers initiated by plasma at atmospheric pressure. Int. J. Adhes. Adhes., 26, 274, 2006. 120. Nithya, S. and Aranganayagam, K.R., Characterization of atmospheric pressure plasma treated polyester fabrics. Rasayan J. Chem., 11, 569, 2018. 121. Gotoh, K., Yakukawa, A., Tanaguchi, K., Water contact angles on poly(ethylene terephthalate) film exposed to atmospheric pressure plasma. J. Adhes. Sci. Technol., 25, 307, 2011.

288  Frontiers of Textile Materials 122. Flynn, C.N., Byrne, C.P., Meenan, B.J., Surface modification of cellulose via atmospheric pressure plasma processing in air and ammonia–nitrogen gas. Surf. Coat. Technol., 233, 108, 2013. 123. Mehmood, T., Kaynak, A., Dai, X.J., Kouzani, A., Magniez, K., Rubin de Celis, D., Hurren, C.J., du Plessis, J., Study of oxygen plasma pre-treatment of polyester fabric for improved polypyrrole adhesion. Mater. Chem. Phys., 143, 668, 2014. 124. Wang, L., Xiang, Z.Q., Bai, Y.L., Long, J.J., A plasma aided process for grey cotton fabric pretreatment. J. Clean. Prod., 54, 323, 2013. 125. Denes, F. and Young, R.A., Surface modification of polysaccharides under cold plasma conditions, in: Polysaccharides, structural diversity and functional versatility, S. Dimitriu (Ed.), p. 1087, Marcel Dekker, New York, 1998. 126. Leroux, F., Campagne, C., Perwuelz, A., Gengembre, L., Atmospheric air plasma treatment of textile materials. Textile structure influence on surface oxidation and silicon resin adhesion. Surf. Coat. Technol., 203, 3178, 2009. 127. Borcia, G., Anderson, C.A., Brown, N.M.D., The surface oxidation of selected poluemrs using an atmospheric pressure air dielectric barrier discharge. Part II. Appl. Surf. Sci., 225, 186, 2004. 128. Nithya, E., Radhai, R., Rajendran, R., Shalini, S., Rajendran, V., Jayakumar, S., Synergetic effect of DC air plasma and cellulase enzyme treatment on the hydrophilicity of cotton fabric. Carbohyd. Polym., 83, 1652, 2011. 129. Fang, Z., Wang, X., Shao, R., Qiu, Y., Edmund, K., The effect of discharge power density on polyethylene terephthalate film surface modification by dielectric barrier discharge in atmospheric air. J. Electrostat., 69, 60, 2011. 130. Popescu, V., Vasluianu, E., Forna, N.C., Sandu, I., Bercu, E., Comparative study of the FTIR analysis and the performances of N,N,N-trimethyl chitosan as wrinkle-proofing agent. Rev. Chim.-Bucharest, 64, 1284, 2013. 131. Popescu, V., Muresan, A., Popescu, G., Balan, M., Dobromir, M., Ethyl chitosan synthesis and quantification of the effects acquiredafter grafting it on a cotton fabric, using ANOVA statistical analysis. Carbohyd. Polym., 138, 94, 2016. 132. Popescu, V., Sandu, I.C.A., Popescu, G., Influence of parameters of polycondensation stage on ethyl chitosan grafting on cotton. Rev. Chim.-Bucharest, 67, 768, 2016. 133. Popescu, V., Sandu, I.G., Vasluianu, E., Sandu, I., Campagne, C., Effects of chitosan grafting onto cotton fabric pretreated with a tetrol. Rev. Chim.Bucharest, 65, 1439, 2014. 134. Popescu, V. and Sandu, I., Multifunctional finishing with tetrol and monochlortriazinil β-cyclodextrine. Rev. Chim.-Bucharest, 65, 811, 2014. 135. Popescu, V., Vasluianu, E., Popescu, G., Quantitative analysis of the multifunctional finishing of cotton fabric with non-formaldehyde agents. Carbohyd. Polym., 111, 870, 2014. 136. Popescu, V., Sandu, I.C.A., Popescu, G., FTIR analysis for studying the possibility of grafting onto cotton of some compounds resulted from interaction

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12 Advanced Dyeing or Functional Finishing Kunal Singha1*, Subhankar Maity2 and Pintu Pandit1 Department of Textile Design, National Institute of Fashion Technology, Patna, Bihar, India 2 Department of Textile Technology, Uttar Pradesh Textile Technology Institute, Kanpur, U.P., India 1

Abstract

Textile wet processing such as dyeing and functional finishing consume a large amount of energy. Today scenario in the textile processing industries required for the conservation of energy or usage of low amount of energy. This can be achieved using different methods such as the use of ultrasound technology, ultraviolet technology, ozone technology, plasma technology, gamma irradiation, laser technology, microwave, e-beam irradiator, ion implantation technology, supercritical carbon dioxide dyeing technology, etc. These techniques have been studied and used for a variety of medium of applications like liquids, dispersions, and polymers. These novel dyeing and processing technologies hold a promise for the applications in the field of textiles. The ultrasound dyeing technique can be very accurately employed for dyeing of the various textile fibers like cotton, silk, nylon, polyester, etc., with the different shade of various dye like reactive, vat, acid etc. The absorbility (% exhaustion and fixation) of the textile materials, their K/S value (color value), and fastness properties have been significantly improved even at a shorter dyeing time and lower dyeing temperature. Thus, by using these novel dyeing and finishing process for the textile materials we can achieve low cost, low effluent, eco-friendly, and sustainable approach without compromising the efficiency. Keywords:  Ultrasound technology, ozone technology, plasma technology, gamma irradiation, laser technology, e-beam irradiator, ion implantation technology, supercritical carbon dioxide

*Corresponding author: [email protected] Mohd Shabbir, Shakeel Ahmed, and Javed N. Sheikh (eds.) Frontiers of Textile Materials: Polymers, Nanomaterials, Enzymes, and Advanced Modification Techniques, (291–308) © 2020 Scrivener Publishing LLC

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12.1 Introduction Textile wet processing such as dyeing and finishing processes requires a large amount of energy. Because these chemical reactions generally occur at elevated temperature to activate the chemical reagents for assisting, accelerating, or retarding the reaction and to transfer reagent mass to the surface of textile substrate across the liquid medium in a reasonable time. There is a recent trend in textile industry to employ energy efficient processes where the process is consuming reasonably less energy. There are various approached have been proposed in literature as novel techniques. These are the reactions in presence of radiofrequency, electrochemical dyeing, microwaves, infrared heating, etc. Among them use of radio frequency or ultrasound technique is probably the most commercially successful one for dyeing and washing of textiles, dispersion of chemicals, polymers etc. Ultrasonic dyeing is getting popularity for dyeing of almost all common textile fibers such as cotton, silk, nylon, polyester etc dyed with reactive, vat, acid dye, etc. Like this method, all other novel methods are also establishing their existence in industrial practice due to many of their merits like better exhaustion, higher add-on, improved fastness, quick process-time, low energy, low discharge, and eco-friendliness. Conventional dyeing process of a textile material is an energy intensive process. It requires high temperature and long time; for example, dyeing of the natural fibers is conducted near boil (90°–95°C) and for the synthetic fibers at 130°C [1–4]. In spite of these stringent dyeing condition, satisfactory quality of dyeing cannot be achieved with the conventional dyeing machines [5–7]. In this context there are some inherent demerits with the conventional dyeing machines which need to be discussed here. • High Temperature–high pressure machine: This is used for dyeing synthetic fiber fabrics. They are highly energy intensive machines [8]. • Jigger Dyeing machine: Needs huge amount of energy to maintain temperatures near boil though the exhaustion level of dyeing are found to be below 70% [9–12]. In spite of spending huge amount of energy, the satisfactory exhaustion level is not achieved and which generates a lots of dyeing related problems like;

Advanced Dyeing or Functional Finishing  293 • Increase in cost due to high energy used [13] • Wastage of the dye [14] references should be in order • Increase in effluents resulting in pollution of the environment [15]

12.2 Mechanism of Dyeing by Phase Separation Dyeing can be considered as a solid/liquid phase process where two processes take place simultaneously like: • Adsorption: This is a fast process. The dye molecules move from the liquid phase of the dye bath to the solid surface of the fiber by virtue of its affinity. • Diffusion: This is a slow process. The dye molecules move from the surface of the fiber to its interior [16–19]. Now by improving these two stages we can also improve the dyeing efficiency of the textile material by the help of acoustic energy like ultrasound energy (forming of acoustic cavitations by building up hot spot and breaking of chemical bonds). Normal human hearing range is 16–20 kHz and the range for ultrasound energy is 20 kHz to 10 MHz [20–24]; this ultrasound is also called as ‘silent sound’ as it falls beyond our audible range (human ears cannot detect the ultrasound) and human cannot hear this kind of sound. The frequency range from 20 kHz to 2 MHz is used in sonochemistry. Frequencies above 3 MHz are more commonly used in non-destructive testing and medical imaging [25].

12.3 Advanced Dyeing and Finishing Techniques 12.3.1 Ultrasound Technology It can be used for dyeing of textile materials by maintaining a vibrating motion having more than 18 Hz to 18–20 kHz. This range of sound is inaudible and it is highly influential in low wet textile dyeing and finishing process since 1950. In practice, three ranges of low or conventional frequency (20–100 MHz), medium frequency and diagnostic or high frequency ultrasound (2–10 MHz) [26] reference just after 26. The important parameters ultrasound dyeing and finishing techniques are;

294  Frontiers of Textile Materials • • • • •

Properties of the solvent Properties of gases External pressure limit External temperature range applied Frequency of the sound wave

The advantages of ultrasound dyeing and finishing process are: • Energy efficient—by lowering temperature and reduced processing times • Environment improvements by reduced consumption of associated chemicals • Lower manufacturing costs and increased competitiveness Improved observations in ultrasound-assisted dyeing process can be conducted by: dispersion, ensuring degassing, and accelerating diffusion, etc.

12.3.2 Ultraviolet (UV) Technology This technique can be applied on cotton and wool materials for dyeing and subsequent finishing by using electromagnetic spectrum of light waves from low frequencies to modern radio communication gamma waves due to its elevated penetration power across the fraction of atom of fabric materials. UV rays can be further classified as UVA (long wavelength, 315–400 nm) and UVB (medium wavelength, 280–315 nm) and UVC (short wavelength, 100–280 nm). UV rays aided textile wet processing helps to achieve even dye shed, deeper shade, chlorine free printing, and also can be eventually used to improve photo bleaching of wool. The required dyeing time for wool is quite less as 60 min with 45–60°C by using C.I. acid Blue 7 [27].

12.3.3 Ozone Technology Ozone gas gives a pungent odor with highly oxidation and bleaching power even at a lower concentration of 0.02–0.05 ppm (by volume), which is quite health safety in all concern. Ozone dyeing can be conducted naturally under solar UV radiation by three most common artificial ways such as corona discharge, UV light, and by electrolysis. Fluorine and hydroxyl ions can be included in this operation to enhance the dyeing or finishing efficiency with a oxidation power of 1.59–3.03 V. The main disadvantages of this process are that they are not eco-friendly and can generate dissolved

Advanced Dyeing or Functional Finishing  295 pollutants by electrophilic attack and can form phenols, phenolate. Ozone dyeing and finishing based processes can be employed on wool, mohair, angora and silk with pH < 4 or pH 4–9 ranges by generating free hydroxyl ions at a temperature of 10–60°C with a solubility of 14–109 kg/m3. There are three main controlling parameters to monitor the process efficiency as temperature, ozone dose and water content of the fiber [28].

12.3.4 Plasma Technology/Ion Implantation Technology Plasma technology can be used as radiant matter with residual molecules of gas in a low pressure tube. Plasma is the fourth state of matter with extremely high changed ions, radicals, and electric field, which can subsequently create gaps insides the molecular layers in a woolen or cellulosic materials. This modern technique can be classified as glow discharge, corona discharge, and dielectric barrier discharge. The various advantages of this process over other existing process are: • Superior cleaning effects • Increase in microroughness−giving snit-pilling finishing of wool • High generation of active radicals • Plasma polymerization • Etching effects • Partial removal of covalent bonds on the outmost layer of the fabric—dust removal • Formation of ample hydrophilic group—creation of various functional group • Cross linking effects The various crucial factors affecting this process are: • • • •

Nature of the gas applied System pressure Reaction time Voltage applied—discharge power [29–35]

12.3.5 Gamma Radiation Technology It is an electromagnetic radiation based process with very high frequency as >1019 Hz with 100 keV and having no mass like all other radioactive

296  Frontiers of Textile Materials materials. The rays are generally produced from radioactive materials as cobalt-60, zinc-65, cesoum-137, and radium-226. The efficiency of this process depends on polymer structure and temperature range during radiation, which can control the reaction rate.

12.3.6 Laser Technology Light Amplification by Stimulated Emission of Radiation (Laser) is a new trending processing way to achieve accurate, fast and automatic dyeing and finishing of textile, leather and garment goods. There are various lasers type as H1 laser or C12 laser are constantly used. This is depends on type of fiber, polyamide structure and coating, crystallinity, dye classes, and wetting properties of the materials.

12.3.7 Microwave Technology Microwaves (MW), having broader frequency spectrum of electromagnetic waves (frequency 300 MHz–300 GHz) that are generally used in broadcasting of radio, TV and radar technology. The wool materials can be used for dyeing and finishing in this process with 35–90 min using 80% dye pick up ratio with minimum usages of reduced energy, water, and appreciable level of quality and cost.

12.3.8 E-Beam Radiation Technology/Mass-Analyzed Ion Implantation Radiation process with aided solid/liquid/gas phases without any catalyst can be used in this process to dye or finish protein and cellulosic goods. This process involves 1–10 eV accelerators particles with higher energy of 300 keV–12 MeV, is done in E-beam machines. Non-polar polyolefins (PE, PP, PS, etc.) can be used to attain higher printability, wettability etc. Mass-analyzed ion implantation can also be done in metal vapor vacuum arc (MEVVA) ion implanter or by direct ion implanter or plasma source implanter instrument alternately [36–40].

12.3.9 Supercritical Carbon Dioxide (Sc. CO2) Technology Supercritical fluids (SCF) having lower temperature than the tipple points (73.8 bar pressure and 31.1°C temperature) and having higher diffusivity and lower viscosity than conventional used dyeing liquor. No auxiliary

Advanced Dyeing or Functional Finishing  297 catalyst or agent is required in this process and it is nontoxic, economical and nonflammable. Protean fibers can be used to dye and finish by this ultramodern process with excellent dyeing hue and fastness properties. The efficiency of this process can be also enhanced by using various metallic ions as Al (III), Fe(II), Cu(II) or Sn(II) with the combination of acid and reactive dyes. This process is accomplished with the help of generating dye miceller structure adhered over the fabric.

12.4 Applications of Ultrasonics in Textiles The effects of ultrasound on textile substrates and polymers have started after the introduction of synthetic materials and their blends to the industry. Application in weaving, finishing and making-up for cutting and welding woven, nonwoven and knitted fabrics (mechanical processes) and sizing, scouring, bleaching, dyeing, etc. (wet processes) [41]. The progress of ultrasound in a dyeing liquor medium The ultrasound waves when propagate into the liquid media result in alternating of mainly two stages or phases; • Rarefaction (low pressure): This is the stretching phase and it occurs when the negative pressure is strong enough to overcome intermolecular binding forces. In details it can be assumed that a fluid (dyeing liquor medium) medium can be torn apart producing tiny cavities (microbubbles). These numerous gas bubbles are formed and expand in the liquid during the expansion phase. This is a low-pressure phase that in essence “cold boils” the water. The water vapor in the bubble condenses rapidly creating a vacuum-filled cavity [29–33]. • Succeeding compression phase: This is the loading phase and it happens due to the great amount of pressure is exerted on the newly expanded bubble and this leads to a sudden implosion of the bubble. The liquid molecules collides releases a vast amount of impact energy that rapidly increases the local temperature producing a high-energy liquid stream and due to that increment of the local dyeing temperature the dyeing liquor can be heated according to a suitable heating cycle of a dyeing process.

298  Frontiers of Textile Materials The mechanisms responsible for the observed advantages gained by employing ultrasound in textile wet processes are a very useful field in the current textile industry. The effects of ultrasonication on both the fiber and the dyebath is the deciding factor to maintain a proper dyeing efficiency [42–46]. It is also believed that because of the segmental mobility of fibrous amorphous regions the dye and also due to the increment of molecular scale interaction the absorbility of the textile materials being improved after ultrasonification.

12.4.1 Principle of Ultrasound Dyeing Technique There are mainly three steps involved in ultrasound dyeing process as dispersion, degassing and diffusion. This technique also facilitate the intensification in mass transport of the dyes during the diffusion stage in the intra-yarn pore will lead to increase in dye-uptake in less time than the conventional dyeing process. • Dispersion: Micelles and high molecular weight aggregates break up to give uniform dispersions in the dye bath. • Degassing: Cavitation expels the dissolved entrapped gas or air molecules from fiber capillaries and interstices at the crossover of fabric into liquid thereby facilitating the dye-­ fiber contact. • Diffusion: It pierces the insulating layer covering the fiber and thereby accelerates the rate of diffusion of the dye inside the fiber and also accelerates the interaction or chemical reaction if any between the dye and fiber [47]. It is also believed that the acoustic cavitation which takes place near the surface of the fiber surface will produce microjets. These microjets facilitate the movement of the dye liquor towards the fiber surface at a much higher velocity. This resulted in increased diffusion of the dyes into the inside of the fiber. Apart from this two other phenomena takes place like localized increase in temperature and swelling effects due to sonification. The enhanced molecular motion and the stirring effect of ultrasound are due to the oscillation of the cavitation bubbles [48, 49]. By the help of NMR technique it has been well-proofed that relaxation experiments, particle size and solubility measurements on selected dyes, and conductivity measurements has been significantly improved after

Advanced Dyeing or Functional Finishing  299 the ultrasonification of the textile materials in case of chemical processing area.

12.4.2 Basic Design of the Ultrasound Dyeing Instrument Developed by SASMIRA, India • Ultrasonic transducers have been incorporated into the existing dyeing machine. The operating frequency range of the transducers was kept at 20–40 kHz. • Modification of the heating mechanism of the existing conventional open width dyeing m/c. Replacement of the regular perforated steam heaters by three electrical heaters of 5 kW each. • Modification of the control panel for incorporation of the ultrasound generators [2, 50].

12.4.3 Different Section of the Machine There are mainly four parts which consisting the ultrasound dyeing machine evolved by SASMIRA, India; • Dyeing section: Fabric dyeing is carried out in this section. Ultrasonic generator provides power to both the tube resonator with required efficiency. • Machine control panel: The switches and indicators are controlled through control panel. • The ultrasound generator section: The ultrasonic generator generates high frequency energy of the range between 20 and 40 kHz. A shielded wire transmits this created electronic vibration to the ultrasound head. The ceramic piezo ring then converts it into mechanical vibrations. The vibrations can be enhanced by the ceramic rings which are fitted into a metal body. It is necessary to maintain a close contact between the sonotrode and the textile goods in order to put this ultrasound into effect [51]. • Ultrasonic tube resonators: The ultrasonic waves are delivered in to the dye bath by the tube resonator. They are the main source of ultrasonic wave emitter in dye bath.

300  Frontiers of Textile Materials • • • •

Length of the tube: 752 mm. Diameter of the resonator: 48 mm. Material of the resonator: SS–316 L. Position of the resonators: Both the ends of the dyeing section.

The ultrasonic dyeing machine can improved some of the following properties like; K/S value, dye uptake, fastness property.

12.4.4 K/S Value The workers proposed that below 60°C the LAC dye has a propensity for the surface coloration and aggregation leading to lower K/S value in case of ultrasonic dyeing for wool (Figure 12.1a) and also for the cotton (Figure 12.1b) in which the de-aggregation is more pronounced. However, above 60°C, the K/S value in the ultrasonic method is more than that in the conventional method. This is because the ultrasonic power results in de-aggregation of the dye molecules thereby leading to the further enhancement of the dye diffusion and the better dyeability than the conventional method in the temperature range above 60°C and the increase in color strength in the ultrasonic case was more pronounced than the conventional method [52]. Furthermore, a plateau is seen in both the methods followed by an increase in the K/S value bath (Figure 12.2a) after 90 min (Figure 12.2b). It has been proposed that the higher dye uptake is due to the de-aggregation of the dye molecules. And the corresponding increase in the dye-uptake (a)

(b) 12

8 Color strength 6 (K/S) 4 2 40

60 Temperature (ºC)

80

100

Color strength (K/S)

10

0 20

With ultrasound treating dyeing Normal dyeing

With ultrasound treating dyeing Normal dyeing 6 5 4 3 20

30

40

50

60

Temperature (ºC)

70

80

90

Figure 12.1  (a) Effect of dyeing temperature on the color strength of dyed wool fabric at dyeing condition: 500 W, M:L (L.R.)::50:1, 50 ml aqueous dye extract (8% w/v). pH 2.5, 1 h and (b) dyed cationized cotton fabric, dyeing condition 500 W, M:L::40:1, 40 ml aqueous dye extract (8% w/v), pH 2.5, 1 h [52].

Advanced Dyeing or Functional Finishing  301 With ultrasound treating dyeing Normal dyeing

(a)

With ultrasound treating dyeing Normal dyeing

(b)

12

160

10 Color strength (K/S) 8

Dye-uptake 80 (mg g-1)

6

120

40 0 0

20

40

60 80 Time (min)

100

120

0

20

40

60

80

100

120

Time (min)

Figure 12.2  (a) Effects of dyeing time on the color strength of dyed wool fabrics, dyeing conditions; 500 W, LR 50:1, 50 ml aqueous dye extracts (8% w/v), pH 2.5, at 80°C (b) dyeing rate with ultrasonification technique and conventional process [52].

after 90 min is probably is due to the longer dyeing time and the remaining high concentration of the dye in the dye) [38].

12.4.5 Dye Uptake It was observed from the graph that the dye uptake values of ultrasonically dyed samples are generally better than those prepared by the conventional heating method. There is decline in the curve in both the cases. But in case of the conventional method it was 60 min while that in case of the ultrasound it was seen to be 75 min. It has been proposed that the higher dye uptake is due to the de-aggregation of the dye molecules [53], and the decline is probably is due to the desorption of the dye molecules as a consequence of the longer dyeing time. It was observed that the dye-uptake values in case of ultrasound were much higher than in conventional method.

12.4.6 Comparison of Ultrasound Dyeing Technique with the Conventional Dyeing Technique for Various Textile Materials Cotton fiber gives better results in its color value when it is dyed with reactive dye (for example; Chikactive Orange ME2R and Chikactive Navy Blue HE2R) at a lower liquor ratio at a lower dyeing temperature and dyeing time, with higher % dye fixation. The cotton dyeing with the vat dye for example with Navinon Blue BC and Navinon Jade Green FFB is also gives the same type of results with

302  Frontiers of Textile Materials higher dye fixation, improved dry/wet fastness, lower dyeing time, temperature than the regular conventional way of cotton dyeing with vat dye (Table 12.1) [54]. The dyeing of manmade fiber like polyester with disperse dye (Rathilene Yellow 3G and Ternix Blue FBL) is widely used in the industry; and ultrasonification dyeing technique has been shown great promise with lesser dyeing time (2.1 h) and lower temperature (50°–55°C) in comparison to regular method with dyeing time (3.0 h) and temperature (95°C) (Table 12.2) [39]. In case of dyeing of the another popular manmade fiber nylon with acid dye Coomassie Red 2B and Neolan Ble 2 GX shows the same trends towards a higher improved side with greater color value (K/S value) and dye absorption in case of ultrasonification dyeing than to the conventional dyeing method. Silk can be consider as a perfect example of the natural protein fiber. Ultrasound dyeing of silk with acid dye Coomassie Red 2B and Neolan Ble 2 GX gives higher than fixation, adsorption and % fixation with higher fastness and brighter color value than the normal conventional way of dyeing. Table 12.1  Data for dyeing cotton with vat dye (shade 1%, M:L::1:8, hydrosulfite: 10 gpl, sodium hydroxide: 15 gpl) [54]. Navinon Blue BC

Navinon Jade Green FFB

Dye

Dyeing technique

Particulars

Conventional

Ultrasonic

Conventional

Ultrasonic

Temperature, °C

80

50–55

80

50–55

Dyeing time, h

3.0

2.1

3.0

2.1

Exhaustion, %

68

74

69

75

Fixations, K/S

4.51

5.76

5.61

6.45

Wash fastness

4–5

4–5

4–5

4–5

Dry rubbing fastness

4–5

4–5

4–5

4–5

Wet rubbing fastness

4

4–5

4

4–5

Advanced Dyeing or Functional Finishing  303 Table 12.2  Data for dyeing polyester with disperse dye (shade 1%, M:L::1:8, dispersing agent: 2 gpl, acetic acid: 2.5 gpl, carrier: 2 gpl) [54]. Rathilene Yellow 3G

Ternix Blue FBL

Dye

Dyeing technique

Particulars

Conventional

Ultrasonic

Conventional

Ultrasonic

Temperature, °C

95

50–55

95

50–55

Dyeing time, h

3.0

2.1

3.0

2.1

Exhaustion, %

73

68

70

68

Fixations, K/S

3.53

2.85

3.19

2.59

Wash fastness

4–5

4–5

4–5

4–5

Dry rubbing fastness

4–5

4–5

4–5

4–5

Wet rubbing fastness

4

4

4

4–5

12.4.7 Dyeing of Polyester by Disperse Dye In the recent time, researches have conducted the dyeing on polyester fabric by DB 56 dye [55] and a higher crystalline dye namely DR 60 with and without ultrasound (Figure 12.3). The dyes uptake in presence and absence of the ultrasound in case of DB 56 was seen to be the same. In both the cases the dye uptake increased with the increase in the temperature specially above the Tg of polyester which is 80°C. However, when the dyeing kinetics was compared with and without ultrasound, no significant increase in the dye uptake and the dyeing rate for DB 56 was observed. On the other hand the results while dyeing of PET with DR 60 with ultrasound resulted in increase not only in the dyeing rate but also the dye uptake. Thus when compared with DB 56, it was observed that ultrasound exhibited a considerable influence on the dye uptake and dyeing rate in case of the crystalline dyes like DR 60. Again, dyeing in case of PET takes place above Tg or Td, above which the free volume increase leading to the diffusion of the dyes into the interior of the fiber. The workers plotted the results of the dye uptake for DB 56 and DR 60 against the dyeing

Dye uptake (dye in gm/fiber in kg)

304  Frontiers of Textile Materials Without ultrasound With ultrasound

20 15

10

5

0

50

55

60

65

70

75

80

85

90

Dyeing temperature, in (ºC)

Figure 12.3  Dye uptake of DB 56 in the presence and absence of the ultrasound radiation [55].

temperatures and observed that the Td does not change with application of ultrasound. Correspondingly, the Tg remains the same in presence or absence of ultrasound.

12.5 Conclusions The conventional wet processes of textiles conducted in HTHP, Jigger and other conventional machines are energy intensive, slow and yield unsatisfactory quality of the product. Non-conventional technologies ate found fruitful regarding energy saving, efficiency, quality and sustainable approach. Ultra-violet technique can be applied on cotton and wool materials for dyeing and subsequent finishing, which is found a low temperature and faster process. Ozone technology requires low concentration of chemicals and fruitful in safety and health concern. Plasma technology has wide spectrum of application and found to be a promising technology in future. Gamma radiation technology is yet to be acquainted with industry for getting popularity. Laser technology is another way to achieve accurate, fast and automatic dyeing and finishing of textile, leather, and garment goods. The wool can be dyed by 35–90 min using 80% dye pick up ratio with minimum usages of energy, water and appreciable level of quality and cost. No auxiliary catalyst or agent is required in the process using super critical CO2 technique, and it is nontoxic, economical, and nonflammable. The use of ultrasonic energy for dyeing point of view is conservation of energy and time and can be effectively implemented in the textile wet processing units.

Advanced Dyeing or Functional Finishing  305

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306  Frontiers of Textile Materials 17. Kamel, M.M., El-Shishtawy, R.M., Yussef, B.M., Mashaly, H., Ultrasonic assisted dyeing III. Dyeing of wool with lac as a natural dye. Dyes Pigm., 65, 2, 103–110, 2005. 18. Santos, H.M., Lodeiro, C., Capelo-Martinez, J.L., The power of ultrasound in Ultrasound in chemistry: Analytical applications. http://www.wiley-vch.de/ books/sample/3527319344_c01.pdf. 2009 19. Vouters, M., Rumeau, P., Tierce, P., Costes, S., Ultrasounds: An Industrial Solution to Optimize Costs, Environmental Requests and Quality for Textile Finishing. Ultrason. Sonochem., 11, 33–38, 2004. 20. http://www.ntcresearch.org/pdf-rpts/anrp98/c95-g13.pdf, 2008. 21. Ferrero, F. and Periolatto, M., Ultrasound for Low Temperature Dyeing of Wool with Acid Dye. Ultrason. Sonochem., 19, 601–606, 2012. 22. Shukla, S.R. and Mathur, M.R., Low-Temperature Ultrasonic Dyeing of Silk. J. Soc. Dyers Colorists, 111, 342–5, 1995. 23. Battu, A., Giansetti, M., Rovero, G., Sicardi, S., Intensification of Wet Textile Processing By Ultrasound Application. Proceedings of the 22nd IFATCC International Congress, Stresa, Italy, 2010. 24. Yukseloğlu, S.M. and Bolat, N., The Use of Conventional and Ultrasonic Energy in Dyeing of 100% Wool Woven Fabrics. Tekstilve Konfeksiyon, 2, 162–167, 2010. 25. McNeil, S.J. and McCall, R.A., Ultrasound for Wool Dyeing and Finishing. Ultrason. Sonochem., 18, 401–406, 2011. 26. Atav, R. and Yurdakul, A., The Use of Ultrasound in Dyeing of Mohair Fibers. 11th World Textile Conference AUTEX, Moulhouse-France, Book of Abstracts, pp. 277–280, 8–10 June-2011. 27. Srikanth, B., The basic benefits of ultraviolet technology. Water Conditioning Purification, pp. 26–27, 1995. 28. http://en.wikipedia.org/wiki/Electromagnetic_spectrum, 2012. 29. http://skincareclub.wordpress.com/2011/02/25/uva-uvb-uvc-rays/, 2012. 30. Bhatti, I.A., Adeel, S., Abbas, M., Effect of Radiation on Textile Dyeing. Textile Dyeing, p.1, 2011. 31. Millington, K., Using Ultraviolet Radiation to Reduce Pilling of Knitted Wooland Cotton. Text. Res. J., 68, 6, 413–421, 1998. 32. Millington, K.R., Comparison of the effects of gamma and ultraviolet radiation on wool keratin. Coloration Technology, 116, 9, 266–272, 2000. 33. El-Sayed, H. and El-Khatib, E., Modification of wool fabric using ecologically acceptable UV-assisted treatments. J. Chem. Technol. Biotechnol., 80, 10, 1111–1117, 2005. 34. Millington, K.R., The Use of Ultraviolet Radiation in an Adsorbable Organohalogen-Free Print Preparation for Wool and in Wool Dyeing: The Siro-flash Process. J. Soc. Dyers Colorists, 114, 10, 286–292, 1998. 35. K.R., Millington, U.S.A. Patent, Application of UV surface treated in textile industry. Red Tech 98 North Americas: UNEB Conference Proceeding Chicago ILLINOIS, America, 1998.

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13 Plasma and Other Irradiation Technologies Application in Textile Kartick K. Samanta1*, S. Basak2 and Pintu Pandit3 ICAR-National Institute of Natural Fiber Engineering and Technology, Kolkata, India ICAR-Central Institute for Research on Cotton Technology, Matunga, Mumbai, India 3 National Institute of Fashion Technology, Department of Textile Design, Mithapur Farms, Patna, India 1

2

Abstract

Chemical treatment of textile is important to remove the natural surface impurities and also to impart different value-added finishing. A large amount of energy and water is used in such treatment due to sequence of multi-step water based processes and drying of wet textile. With the increasing environmental concern in the recent years along with eco-friendly process/products, and the government legislation on effluent discharge in many countries, sustainable processing is one of the major challenges in textile sector. Various groups of researchers are involved in sustainable processing/finishing of textile using biomolecules, aromatic and medicinal plant extracts, nano materials, and water-free irradiation techniques. Surface modification of fiber and fabric has been found to be effective for some specific applications. Chemical treatment like chlorination, alkali treatment, synthetic polymer coating, etc. have also been developed for modification of textile surface. These processes are often found to be harsh, non-ecofriendly, modifying the bulk properties of materials and generating effluent. Cold plasma in low pressure to atmospheric pressure conditions in the presence of non-­polymerizing to polymerizing precursors has been used to improve/introduce a new or existing property of a textile substrate. The UV excimer irradiation has used to impart smart attributes in woolen and silk fabrics, having hydrophobic property in one surface and hydrophilic property on other surface. Likewise, different laser sources viz., beams of Nd : YAG, CTH : YAG, and CO2 laser were reported for treatment of denim fabric. Water-free electron beam technology has also been *Corresponding author: [email protected] Mohd Shabbir, Shakeel Ahmed, and Javed N. Sheikh (eds.) Frontiers of Textile Materials: Polymers, Nanomaterials, Enzymes, and Advanced Modification Techniques, (309–334) © 2020 Scrivener Publishing LLC

309

310  Frontiers of Textile Materials used for treatment of textile effluent. The chapter highlights the applications of emerging irradiation techniques, viz., plasma, ultraviolet (UV), laser and electron beam in textiles. Keywords:  Water-free processing, textile, plasma, laser treatment, electron beam application, UV treatment

13.1 Introduction Textiles are manufactured to execute number of functions. Wet-chemical processing of natural fiber based textile is much essential so as to remove the natural impurities from its surface to make it apposite for coloration and other value added finishing, in addition to improvement in aesthetic value. Water and energy are consumed in nearly every step of textile processing. Wet-chemical processing of textile is water and energy intensive due to involvement of multi-step processes viz., desizing, scouring, bleaching, coloration, and different value added finishing, involving operations like padding, drying, curing, washing, post-washing, etc. [1–3]. These processes enhance the production cost as drying of wet textile is costliest operation as far as textile processing is concerned. A large amount of water is used from preparatory processing to finishing stages of textile that is discharged mostly as an effluent mixed with unused coloring material, pigments, sizing material, alkali, salt, acid, dust and dirt, unused various finishing chemicals and several other auxiliaries [4, 5]. Discharge of such processed water in a large water body has a serious impact on water pollution. In the recent past due to the stringent environmental effluent norms, the textile industries are now slowly moving toward the adoption of ecofriendly processing technologies. Some of the technological improvements in this direction for textile processing with the aim to reduce the consumption of energy, chemical and water, and also to reduce the effluent generation and cost of process/product are: (i) material processing with low M:Lr, (ii) finishing using spray and foam techniques, (iii) enzymes application, (iv) use of natural colors/dyes, (v) digital printing, (vi) use of infrared in textile processing, (vii) R.F. drying, (viii) use of ultrasound in textile processing, (ix) use of natural dyes, and different aromatic and medicinal plant extract for UV protection, antibacterial, mosquito repellent and well-­being textiles, (x) application of biomaterials, like silk sericin, neem extract, and aloe vera for health and hygiene products, (xi) surface modification for coloration or finishing [5–8]. Additionally some more potential technologies have also been emerged in the laboratory and poised to travel to the industry level for value addition of various textile are the usage of:

Plasma and Other Irradiation Technologies  311 (i) nanomaterials viz., nanoparticles, nano-fiber, nano-coating, nano-rods, (ii) supercritical carbon dioxide assisted processing, (iii) plasma treatment for water-less treatment, and (iv) ultraviolet as well as laser treatment in textile [3, 4, 6, 9–11]. Although several technological advancements have been occurred in textile chemical processing, still some of the processes remain water and energy intensive, in addition with use of some non-ecofriendly chemicals. In the context of environmental pollution, carbon footprint, climate change, and hygienic products, the demand of eco-friendly textiles is increasing profoundly. Along with use of natural fiber, efforts have also been made to use natural extract, biomaterial, bio-molecules and green materials for value addition of textiles. Some of the following extracts/molecules have been used successfully for different functional finishing of textiles, e.g., banana sap, pomegranate rind extract, spinach juice, green coconut shell extract, DNAs and proteins, natural dyes, mulberry fruit extract, silk-sericin, tulsi, nano-lignin, almonds, aloe vera, chitosan, honey, cucumber, mint, sandalwood, lavender, jasmine, and champa for flame retardant, UV protective, antimicrobial, natural coloration, skin nourishing, aroma and wellbeing finishing of textiles [2, 8, 12–14]. At the same time, recycling and reuse of synthetic polymer/fiber is also being practiced for analogous or other applications. Various chemical methods such as, chlorination, alkali treatment, synthetic polymer coating, etc., are reported for modification of textile. However, sometimes these processes are often found to be harsh, non-ecofriendly, modifying the bulk properties of materials, and also, generating noticeable effluents [15, 16]. On the other hand, fiber surface modification by physical means has also been explored in details to improve various fabrics properties. Different irradiations viz., UV rays, gamma rays, plasma, and laser are being utilized in chemical processing of natural and synthetic textiles [11, 17–20]. Of these, the plasma and ultraviolet (UV) method are the clean, cheaper and multipurpose option, besides their advantages of environmentally friendly, dry and energy saving process over the traditional process. Plasma irradiation is used for modifying the textile surface by physico-chemical reaction, resulting increase in dye uptake and other finishing chemicals at lower temperature and shorter time. Likewise the UV irradiation has recently been used by researchers to modify the surface properties, and for dyeing of silk, wool and polyester fiber [11, 21–23]. The UV treatment can alter the wool fabric to control its felting shrinkage as well as pilling resistance properties [24]. Laser based surface modification is normally used in aerospace, optoelectronics, automotive industries, medical sector, etc. However, in some of the areas laser rays also has been

312  Frontiers of Textile Materials explored for modifying the surface and designing the textile materials [20, 25]. Very recently, in this direction, electron beam technology has also been explored for eco-friendly and clean biodegradable effluent treatment [26, 27]. Thus, prospect of emerging water-free UV, plasma, laser and electron beam irradiation technologies for value-added processing and finishing of textile substrates has been summarized in the present chapter [28–32].

13.2 Plasma Treatment of Textile Plasma processing in textile operations starting from preparatory to finishing is getting importance due to its advantages possibility of completion of multi-steps operation in a single step without usage of water as a processing medium. Plasma, an ionized gas, contains positive and negative ions, electrons, neutrals, excited molecules, photons, and UV light. It is a promising technology for textile processing so as to develop value-added technical, home, and apparel textiles at a comparatively lower-cost. Unlike water based wet-chemical processing of textiles, the main desirability of plasma for commercial application is to avoid of water in processing, thus addressing the generation of liquid effluents. Other key advantages of plasma treatment of textile are swift processing, conservation of energy and chemical, reduction in operating cost, and high-efficiency as reported details in Table 13.1. The effectiveness of plasma treatment depends on following factors viz., gas flow rate and type of gas used, chamber/ reactor pressure, plasma discharge power, treatment time, and ageing of plasma-treated surface. Active molecular fragments such as, free radicals, are generated, when the chemical bonds are cleaved by the 0–5 eV energy of cold plasma. Atmospheric pressure non-equilibrium plasma (cold plasma) could be utilized for uniform and continuous surface modification of textile material. Extension of atmospheric pressure plasma application to graft co-polymerization is a novel technique that provides permanent covalent bonding of a polymer onto the fabric. Plasma treatment of textile fetches physico-chemical alternation of top fiber surface without changing the bulk attributes of fibrous materials. Among the different categories of plasma used for polymer modification, only the low-temperature plasma, popularly called as cold plasma (temperature < 250°C), is suitable for nano-scale surface engineering of textile. Atmospheric pressure plasma is cost effective and has the possibility of integration with other textile processing line. It is becoming popular in

Plasma and Other Irradiation Technologies  313 Table 13.1  Comparison of conventional textile process with plasma process [4, 5]. Different textile processes

Textile processing without plasma treatment

Textile processing using plasma

Processing medium and water requirement

Water based Approximately, 100 l/kg for cotton textile starting from desizing to finishing.

Ionized gas based Water is not required for a particular process, e.g., hydrophobic finishing of textile.

Dyeing process parameters, dye utilization and auxiliaries requirement

Majority of textile dyeing is carried out near boiling temperature for 60–90 min in the presence of acid/alkali, salt, etc., resulting increase in effluent load.

Dyeing temperature and/ or time can be reduced significantly, e.g., plasma treated wool and silk can be dyed 60

sample. Water absorbency time was evaluated by placing a water droplet (37µl) and the time to absorb the water droplet in textile was recorded. Water absorbency time was found to increase linearly with increasing plasma treatment time, possibly due to reaction of more amount of fluorocarbon gas with cotton cellulose. For the 3 min plasma irradiated sample, i.e., total fluorocarbon gas flow 600 ml, water absorbency time enhanced to increased to 9 min, while keeping helium flow rate constant at 600 ml/min (Table 13.2). Water contact angle was found to increase notably from ~0° to 142° in the untreated to 12 min plasma treated samples, respectively. In plasma based hydrophobic modification of cotton, no water was used, thus process may be considered as an environment friendly [19].

13.4.1 Surface Chemistry of Hydrophobic Textile Hydrophilic cotton textile turned to hydrophobic up on plasma treatment due to reaction of different fluorocarbon species such as, –F, –CF, –CF2, and –CF3 with cotton cellulose. The ATR-FTIR analysis of plasma treated samples shows the presence of various fluorocarbon species, such as absorption peak of > C = CF2 at 1750 cm−1, –CF stretching in –CF2CF3 at 1368 cm−1, –CF2 asymmetric stretching at 1270 cm−1, –CF2 symmetric stretching at 1160 cm−1, and –CF3 absorption at 970 cm−1 [19]. The result indicates the fragmentation of fluorocarbon molecules and followed by its reaction with cotton polymer. Chemical composition of untreated and plasma treated cotton was also studied using mass spectrometer. Figure 13.5 shows the major mass peaks at 1 amu (H−), 12 amu (C−), 13 amu (CH−), 16 amu (O−), and 17 amu (OH−). In plasma treated sample in the presence of helium-fluorocarbon, there was a strong mass peak at 19 amu for F− as shown in Figure 13.6 [19, 43]. It was noted that the intensity of F− peak at 19 amu was remarkably higher compared to other mass peaks, such as H−, C−, CH−, O−, and OH−. Furthermore, the intensities of O− and OH− molecules drastically reduced

318  Frontiers of Textile Materials after plasma reaction. This may also be responsible for hydrophobic transformation of cotton cellulose in addition with attachment of various fluorocarbon fragments. Other mass peaks that were also detected are 39, 43, 69, 85, 93, 109, and 135 amu. Among these, 69 amu mass peak corresponds to CF3−, 131 amu corresponds to C3F5, and 93 amu corresponds to C3F3. Presence of above fluorine containing molecules on plasma treated cotton fabric surface facilitated it to become hydrophobic. Chemical image derived from mass spectroscopy was utilized to analyze the distribution of different molecules on plasma treated cotton textile surface and the result was compared to untreated cotton textile. In an untreated sample C− and O− are evenly distributed over the entire fabric surface (Figure 13.5). On the other hand, plasma modified sample (Figure 13.6) looks typically bluish in color, owing to presence of more amount F− molecule on surface. The F−, C−, and O− molecules were also evenly dispersed on the entire fabric surface, indicating uniform modification [19]. 1.0E+6 8.0E+5

Counts

Untreated cotton

H

1.01

C, O distribution

6.0E+5 O

4.0E+5

15.99

2.0E+5

17.00

13.01

0

0

5

10

F

OH

C 12.00CH

15

Mass [m/z]

Figure 13.5  Negative mass spectrum of untreated cotton (Color notation: Red for C− at 12 amu, Green for O− at 16 amu) [19, 43].

Plasma treated cotton 1.5E+6

19.00

Counts

C, O, F distribution

F

H 1.01

1.0E+6

5.0E+5

CH C

OH O 16.00

0 0

5

10

15

Mass [m/z]

Figure 13.6  Negative mass spectrum of fluorocarbon plasma treated cotton (Color notation: Red for C− at 12 amu, Green for O− at 16 amu, and Blue for F− at 19 amu) [19, 43].

Plasma and Other Irradiation Technologies  319 Individual fibers in the yarn structure along with the typical twisted ribbon like attribute of cotton fibers are also easily visible in the plasma treated sample (Figure 13.6). This is an indication of nano-scale surface modification of fibers without hindering inter/intra fiber-spacing/features. The SF6 non-thermal plasma was utilized for imparting hydrophobic functionality in silk fabrics [44–47]. Plasma jet in Ar gas was utilized for grafting nondurable phosphorous containing flame retardant chemical on silk [48]. Further argon induced graft polymerization of only 5% phosphorous containing monomers followed by SF6 plasma treatment exhibited excellent thermal stability as well as water repellent property compared to untreated sample. Water repellent finishing of textile (cotton) was also investigated by treatment with siloxane or perfluorocarbon plasma. Hexamethyldisiloxane derived plasma polymers were utilized for water repellent finishing of cotton leading to a smooth surface with achievable water contact angles up to 130°, keeping fabric’s water vapor transmission property unchanged [49]. Plasma reaction in the presence of different gaseous monomers like, methane (CH4), ethylene (C2H4), and acetylene (C2H2) can impart a film-like coating of cross-linked amorphous hydrocarbon layers that can impart water repellent property. Plasma treatments using CF4 and C3F6 on cotton denim fabrics in low-pressure plasma were found to increase the surface hydrophobicity as evaluated by increasing in contact angle value. For example, in cotton water contact angle changes from 30° in a control sample to 90°–150° in plasma modified sample, depending upon the pressures of the plasma reactor and treatment time. Overall hydrophobicity of the treated desized denim fabrics was found to be higher than that of treated sized denim fabrics, indicating that the sizing material on denim fabric plays a role in determining surface wettability even after fluorination in the presence of CF4 and C3F6 plasmas [50]. Plasma treatment with O2 in presence of hexafluoroethane was studied on cotton textile to incorporate an effectual barrier to aqueous contamination [51]. Low pressure, non-thermal RF plasma reaction of HMDS and HMDSO under various plasma power and treatment time on cotton as well as polyamide fabrics is also reported [52]. Hydrophobicity of polyamide fabrics was observed to increase profoundly, and the treatments were observed to get slow down the vertical flame spread in cotton fabrics in a very short time with very minimal amount of chemical without using water and auxiliary agents. A combination of hexafluorethane (C2F6) and hydrogen was also investigated as barrier toward hydrolysis of aramid fabric, e.g., Nomex. The deposited thin film keeps the fibers intact, when it was immersed in 85% H2SO4 solution for 20 h at ambient temperature, as compared to conventional fluorocarbon finishing [53]. Plasma treatment

320  Frontiers of Textile Materials with O2 in presence of hexafluoroethane is suitable to impart hydrophobic characteristic on cotton fabric due to the reluctance of fluorinated cotton to absorb the aqueous solution.

13.5 Improvement in Liquid Absorbency and Coloration Scoured and bleached cotton fabric being pure a cellulose substrate possess high liquid absorbency. Water took significantly higher time to move up to 3 cm height in the control sample, compared to 4 min helium and helium/ oxygen plasma modified sample, respectively. It was noted that helium/ oxygen plasma modified samples took a bit lesser time in comparison to helium plasma modified samples to move the same height. The result showed better liquid transportation by the plasma modified sample, possibly owing to etching of fiber surface by plasma impingement and formation polar groups. EDX study depicted the presence of 44.5% oxygen and 55.5% carbon in the unmodified cotton textile. The oxygen elemental percentage was observed to enhance profoundly to 48% and 48.2% in the helium and helium/oxygen plasma modified samples, respectively. This might have helped in formation of polar hydroxyl, carboxyl, and carbonyl groups that may be the causal factor for improved liquid wicking in the plasma modified cotton samples. The water absorption in 5 min nitrogen (N2) plasma modified woolen textile decreases from 180 s in the unmodified sample to 1 s in the plasma modified sample. There was also formation of more numbers of NH2 group and surface oxidation, and the nitrogen and oxygen content in the plasma treated fabric increased noticeably. Surface oxidation of wool fiber was confirmed by measuring the shift in binding energy (XPS analysis) of sulfur from 163 eV to 168 eV after the plasma treatment. This leads to formation of sulfonic acid due to oxidation of disulfide linkage upon plasma modification. This leads to reduction in sulfur (S) atomic percentage from 2.58 to 2.23 in the unmodified to plasma modified samples, respectively [54]. The ESR result shows presence of stable free radicals attributed to the carbon and oxygen centered in wool fiber. Upon plasma treatment the area under ESR curve increased by 18.2 times with G factor 2.007. It might be owing to formation of higher nitrogen centered free radicals on the irradiated wool fabric surface [55]. Similar result was also seen, when the wool was subjected to plasma treatment in the presence of oxygen. There were two more physico-chemical changes such as (i) further generation of –C = O, –OH, –COOH groups, which are causal for higher dye uptake, and (ii) slight improvement crystallinity in plasma modified sample. The reduction

Plasma and Other Irradiation Technologies  321 in S percentage was also observed for oxygen plasma treated sample [56]. Atomic force microscope (AFM) micrographs shows even after 2 min of O2 plasma exposure leads to formation of widened striations and showed rough bark like appearance with the presence of small pits and micro-­features distributed over the wool scale surface. This plasma enhanced surface etching also leads to increase in surface area from 0.1 m2/gm to 0.35 m2/gm [53]. An atmospheric pressure glow discharge reactor was utilized to promote the adhesion of water-based inks on polypropylene sample with air/O2/He plasma. Initial surface tension of 31 dynes/cm increased to 52 dynes/cm, and there was complete retention of ink in plasma modified surface. Di-electric barrier discharge (DBD) plasma treatment on polypropylene, wool, and cotton could alter their hydrophobic characteristic into hydrophilic. Specific surface areas profoundly enhanced in cotton and wool, increasing percentage of dye uptake [53]. Atmospheric pressure plasma treatment with He/ Ar and acetone/Ar on Merino wool for 30 s treatment increased dyeing rate [57]. Air and dichlorodifluoromethane (DCFM) plasma treatment on cotton fabrics caused surface modification, and also improved dyeability with reactive and natural dyes, but slightly decreased dyeability with direct dye [58]. Polyamides are widely used being semi-crystalline engineering thermoplastic materials that also yield excellent fiber. Oxygen and air plasmas were used to increase the wettabliity and dyeablity of the fibers. In an industrial production process, an air plasma treatment on polyamide was observed to increase the bond strength changing the bond from adhesive to cohesive. Similarly, with the mixture of acetylene and ammonia (C2H2/ NH3) plasma on textile, a slight increase of wettability was also seen [59]. Highly crosslinked plasma induced coatings with accessible functional groups can give multifunctional textile surfaces with wettability, bio-responsive surfaces and anti-bacterial. Plasma in the presence of nitrogen has been utilized to enhance the printability, wettability, and bond forming tendency [60]. When nylon-6 textile was treated with non-­thermal plasma using three non-polymerizing gases such as, tetrafluoromethane, argon and oxygen, there was a slight decrease in air permeability of the treated fabric, probably due to change in fabric’s surface morphology owing to plasma treatment. In manmade fiber, plasma treatment causes fiber’s surface etching and formation of various polar groups, which leads to improvement in coloration with basic dyes. Polyester fiber with inherent hydrophobic nature is lacking in stain-release, anti-soil, soil re-­deposition, adhesion, and antistatic properties [61]. To improve the hydrophilic characteristic of polyester fiber, chemical modification and the surface chemical treatment, after processing was undertaken. In plasma treatment compressed air was used as a reactive gas source. Damage to fabric due to plasma treatment was not

322  Frontiers of Textile Materials significant. It was observed that plasma treatment could enhance the wettability, concentration of oxygen and surface roughness, resulting increase in water wicking and anti-static properties. The dye pick-up uptake was better due to enhance in nano-scale roughness and single fiber wettable attribute in the plasma modified sample. Plasma pre-treated cotton textile exhibited higher and brighter color shades after dyeing than untreated sample. Plasma could help the cotton textiles to take up more dye molecules from the dye bath, however little effect on color fastness of textile material was noted. Plasma treatment on cotton in contact of oxygen or air gas increases the dye uptake of Chloramine Fast Red K and rate of dyeing, in absence of electrolyte in the dye bath [62]. The effect depends more on the oxygen component of air than the nitrogen component. Air plasma was observed to be less effective than the oxygen plasma. Plasma treatment improves the inkjet printing on polypropylene partly due to hydrophilic modification of the substrate and partly due to improved sorption of inks on samples. Atmospheric pressure plasma in the presence of hexamethyldisilane (HMDS) and tris (trimethylsiliyoxy) vinylsilane (TTMSVS) were utilized to increase the color strength by generating an anti-reflective layer on fabric surface [63]. Plasma treatment with nitrogen under a pressure of 2 mbar induced in situ polymerization of acrylic acid 10–20% w/w on polyester, polyamide and polypropylene (PP) fabrics for 5–15 min exposure in different plasma power of 25, 50, and 75 W [64]. Wash fastness of the sample was acceptable for polyamide and unsatisfactory for polyester and polypropylene. On oxygen plasma treatment of ramie fabric by radio-frequency (RF) plasma discharge, the crystalline-indices of ramie fiber were slightly reduced. In the plasma treated surface, due to formation of hydrophilic group such as, hydroxyl (–OH), carbonyl (= CO) lead increase in surface energy, capillary effect, wettability and dyeability of the ramie fabric. A glow-discharge like plasma of Ar and O2 mixture (10:1) was used to modify polyester fabric. Color strength of the dyed polyester textile was enhanced approximately by 50% and the relative dye up-take increased by about 18% after the treatment, without degrading the dyeing fastness of the textile.

13.6 Plasma Treatment of Protein Fiber 13.6.1 On Silk Fiber India is the second largest producer of raw silk and the largest consumer of silk based fancy materials. It is a continuous protein filament fiber

Plasma and Other Irradiation Technologies  323 produced by insects. Silk fiber is mostly secreted by silkworm Bombyx mori and obtained from silk cocoons. Once the raw silk is obtained from the cocoon, it would pass through several stages of processing before usage as a textile. The gum coating (sericin) would be softened by immersion in soapy hot water. In the next stage is silk throwing, which constitutes a separate process by itself. The process covers a whole range of operations by which very fine silk threads are twisted and doubled into more substantial yarns. Then the silk would be boiled in water to remove the natural gum and the process is called as degumming. More the natural gum is removed better is the silk fiber quality. Silk typically consists of two structural elements: silk fibroin (a structural protein material which forms the inner layer) and sericin (a kind of gum which forms the outer layer). Each silk fiber is formed by twin filaments composed of fibroin, which cemented by sericin. These two elements are present in the proportion of about 75% fibroin and 25% sericin [65]. Silk was plasma treated using various reactive and non-reactive gases with an aim to enhance the hydrophilic attributes. The enhancement in hydrophilic characteristic along with increase in surface roughness has been utilized for improvement in coloration using different dye classes such as acid, reactive, and metal complex by numbers of research group. Tussar silk textile after modification exhibited wicking height of 28 mm in 2 min, but the untreated silk fabric clear saturation was observed after 100 mm. As far as quality of Eri as well as Muga silk is concerned, plasma modification enhanced the rate of wicking nearly doubles in comparison to saturation length of untreated silk. Co-efficient of friction of silk fabric increased after the plasma irradiation. Low pressure (at 60 Pa) plasma modification in the presence of O2, N2, and H2 atmosphere for 30 min, co-efficient of friction of the treated fabric increased to in between 0.7–0.8 in comparison with 0.27 of the control fabric. After plasma treatment of silk fabric, slight flutes appeared and also fibrillar unit was more evident in treated silk [66]. Crystallinity of the treated fabric slightly decreased. In all the plasma modified sample surface etching, roughness, and weight loss increased with increasing plasma modification time. After 30 min plasma exposure caused around 4–5% losses in sample weight. After plasma treatment in O2 and N2 atmosphere both the O/C and N/C atomic ratios enhanced marginally as measured in XPS data. However, after H2 plasma treatment both the ratios decreased slightly. Effect of NH3 plasma on silk fabric at atmospheric pressure has also been studied. The nitrogen plasma treated silk fabric was dyed at lower temperature and different process parameters related to dyeing were optimized using Box–Behnken design (BBD) [67]. In this regard, degummed silk textiles were plasma modified in O2, N2, and

324  Frontiers of Textile Materials H2 atmosphere for 5 min duration and were dyed with Ramazol reactive dye at 50°C for 90 min. Color strength of the modified fabric improved notably in comparison to unmodified silk textile. It was found that in the 5 min plasma modified and dyed textile at 6% shade produced equal color strength, when the unmodified textile was dyed with 10% shade, possibly due to formation of more number of active dye sites [66].

13.6.2 On Wool Fabric Physical characteristics viz., thermal, water vapor permeability and frictional were found to improve, when the knitted woolen fabric was treated with O2 plasma. However, the pilling property, thermal conductivity and air permeability decreased [68]. It might be due to increase in fabric thickness and change in surface morphology of wool textile after plasma modification. After O2 plasma treatment, the important mechanical properties like compression, tensile strength and bending of modified fabric were also changed [69]. It is reported that the contact angle, wicking property, scourability, and dyeability of woolen textile were changed due to O2 plasma irradiation [70]. Plasma enhanced etching as well as new dye sites formation were not sufficient for enhancement in case of dyeing with acid and chrome dyes at equilibrium. It seems that if the final dye sites are increased, exhaustion also increased [69]. If O2 plasma could be used for 5  min at plasma discharge power of 30 W followed by dyeing of wool fabric in combination of commercially available 1:2 metal complex dyes at 80°C, 85°C, and 98°C at neutral pH with M:L = 1:65, then final dye bath exhaustion in the plasma modified sample may be compared with the unmodified sample, dyed at 85°C. Plasma pre-treatment in a continuous manner is also feasible for continuous application of natural dyes on wool. In this regard, plasma treatment improved the natural dye uptake in comparison to the unmodified sample, which was dyed in the presence of copper sulfate as a mordant [37]. Similar to dyeing, plasma treatment in air atmosphere improved the adhesion and penetration of printing paste on wool fiber and decreased the hairiness. The increase in penetration resulted with higher color yield at lower steaming treatment and absence of wetting agent [71]. Though wool fiber has high moisture regain, its surface is mostly hydrophobic in nature. Exposure of wool fabric in plasma has also reported for anti-felting of woolen textile. Plasma treatment could break the scales and oxidizes the upper fatty hydrophobic layer and helped in producing shrink-proof-wool [53]. As a result of this, an unmodified woolen textile showed 12.3% shrinkage compared to only 2% in the plasma modified sample [56]. Scanning electron microscope pictures revealed that the O2

Plasma and Other Irradiation Technologies  325 plasma exposure could etch the wool fiber surface and could break the part of the surface scales that helped in anti-felting characteristics [72].

13.7 UV Irradiation Ultraviolet (UV) irradiation with wavelength lower than 200 nm was found to be effective to modify the fabric surface with functional groups formation and physical etching [73]. It mainly emits highly energized photons that react with atmospheric air and forms ozone gas in the ground state, which again dissociates into oxygen and nascent oxygen (excited state). It is a continuous association and dissociation process. When the excited species fall upon the textile substrate surface, it generates some free radicals on the surface in concurrence with etching of material surface. Like plasma treatment, UV ray is also quite effective on the protein fibers like wool and silk. Most of the literatures reported that the UV irradiation helped to break the scales of wool and also etched the nano-layer thick fatty scales on its surface, thus reducing in directional frictional effect. As a result wool can be made shrink proof without using of further chemicals. Another research group has reported that pre-­ irradiated by UV rays at inert nitrogen atmosphere, wool can be made easily accessible to anionic acid dye. It may be due to creation of more amounts of amine groups on the fabric surface that help to catch more acid dye molecules from the dye bath. On the other hand, UV irradiation in air or oxygen atmosphere creates negatively charged carboxylic and hydroxyl groups on the fabric surface and help to catch more basic dye molecules. Only challenge in this process is that there are chances of uneven dyeing and ring dyeing after UV treatment. In addition, active species generated on the fabric surface may be changed with time due to ageing effect. A double hydrophilic/hydrophobic smart woolen textile, having hydrophobic property on one face and hydrophilic on other face, was prepared by first padding the sample with fluorocarbon based formulation followed by 172 nm UV excimer lamp irradiation on one surface of the fabric. The treated sample was then characterized by measurements of contact angle and vertical wicking behavior [74]. It was seen that on the irradiated side the contact angle dropped to 10° after UV treatment. It might be because on irradiation with the UV excimer lamp (172 nm), the fluorocarbon (F/C) finish consisting C-F bond has dissociated and undergone a photo oxidation reaction involving defluorination of the surface and incorporation of oxygen as CF–O–CF2, CF2–O–CF2, and CF–O–CF3 moieties [11, 22]. Additionally, some extra polar groups like C = O and

326  Frontiers of Textile Materials –COOH might have also been formed on the 30 min irradiated fabric surface. However, the other side of wool fabric exhibits lotus effect attributes [74]. The UV excimer lamp has also significant effect on the silk fabric surface. UV treatment has reduced the wetting time of the irradiated silk fabric significantly compared to untreated silk fabric. In addition, the rate of wicking in the treated fabric was also improved notably [21]. Similar to above woolen smart textile, the process for developing double hydrophilic/hydrophobic mulberry silk textile using 172 nm excimer lamp is also reported along with mechanism of such surface [75].

13.8 Laser Irradiation Laser emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. Kan et al., in 2008 has reported the effect of laser irradiation on the properties (fabric weight, abrasion, bending, luster, wetting, fiber diameter, etc.) of polyester fabric. They have reported that the laser ray only affects the surface properties of the polyester fabric. The performance and comfort properties of the laser irradiated polyester fabric have been changed after laser ablation [25]. In the recent time, Morgan et al., in 2014 has established the dyeing behavior of CO2 laser irradiated wool fabric. It has been reported that laser irradiation approach has the promising effect on reduction of energy and water consumption. Laser irradiation improves the dye uptake of woolen textile. However, there was some tonal variation on wool fabric. Same research group has also created various designs on the wool fabric surface by color fading phenomena with the help of laser rays [20]. Chow et al., in 2012 has reported the treatment of cotton fabric with CO2 laser. The pixel time and resolution of laser for application purpose were studied; fabric weight and strength decreased with increasing of resolution and pixel time [76]. Treated fabric turns yellowish after treatment. Very recently, the effect of CO2 laser treatment on the fabric’s hand of cotton and cotton/polyester blend fabrics has been reported. Connected with the fabric hand properties, fabric’s stiffness, smoothness, softness, wrinkle recovery, drapability, etc., were measured and concluded that laser treatment has sufficient capability to change the mentioned hand properties of the fabric. Three laser sources viz., beam of Nd : YAG laser (1. 064 µm and its second harmonic 532 nm), CTH : YAG laser (2.09 µm) and CO2 laser (10.6 µm) were studied for textile treatment, specially for denim processing; out of which the CO2 laser was appeared to be the most apposite for denim processing [3].

Plasma and Other Irradiation Technologies  327

13.9 Electron Beam Irradiation Electron irradiation is composed of highly energized electrons. Normally, energy of electrons varies from the KeV to MeV ranges, depending on the depth of penetration is required. The irradiation dose is generally measured in grays. An electron gun consisting of cathode and anode is used to generate and accelerate the primary beam. In the last few years, electron beam technology has been used popularly for textile effluent treatment. The treatment of textile effluent and non-ionic ethoxylated surfactant by electron beam for removal of color and toxicity from it has also been reported recently. In the same line of work, Deogaonkar et al., in 2019 has reported the electron beam irradiation treatment for the degradation of non-biodegradable contaminants in textile waste water. As per the report, electron beam radiation (80 kGy) helped in biodegradation of effluent, generated from textile desizing, scouring, bleaching, dyeing, and finishing processes. Biological-oxygen-demand (BOD) and chemical-oxygen-­ demand (COD) of the waste effluent, before and after the electron beam treatment was also studied [27].

13.10 Summary Wet-chemical processing of natural fiber based textile is much essential so as to remove the natural impurities from its surface, thus making it apposite for coloration and value added functionalization. Nevertheless, the process is energy and water intensive owing to involvement of multi-step processes. Off-late, with the stringent environmental effluent regulation, there were development/validation/implementation of several ecofriendly/green processing technologies in textile. Some of these advancements are (i)  reduce the liquid ratio in processing, (ii) spray and foam finishing, (iii)  application of biomaterials, natural dyes, natural extract, enzymes, bio-molecules, (iv) digital printing, (v) use of infrared and radio-­frequency, (vi) ultrasound application, (vii) use of water-free irradiation technologies viz., cold plasma, UV rays, laser, and electron beam. Generation of cold plasma in the low pressure to atmospheric pressure conditions in the presence of non-polymerizing to polymerizing gaseous/ liquid molecules has been used to improve/introduce a new or existing property in textile substrate, like water absorbency, wicking, oil absorbency, water and oil repellent, flame retardant, antimicrobial, UV protective, dye exhaustion, adhesion, and anti-felting of wool. Ultraviolet (UV) irradiation with the wavelength lower than 200 nm was found to be quite

328  Frontiers of Textile Materials effective for modification of fabric surface due to functional groups formation and surface etching. A 172 nm UV excimer lamp irradiation was used to impart smart attributes in woolen and silk fabrics, having hydrophobic property in one face and hydrophilic property on the other face. An UV treatment could also reduce the wetting time and also improves the dye uptake of the irradiated fabric. Laser irradiation improves the dye uptake of woolen textile. Fabric weight and strength get reduced with increasing the resolution and pixel time of laser treatment. Efficacy of laser treatment on cotton and polyester/cotton blend fabric’s hand properties has also been reported. Similarly, water-free electron beam technology was used for treatment of textile effluent.

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Plasma and Other Irradiation Technologies  329 10. Sharma, V., Basak, S., Rishabh, K., Umaria, H., Ali, S.W., Synthesis of zinc carbonate nanoneedles, a potential flame retardant for cotton textiles. Cellul., 25, 6191, 2018. 11. Gupta, D. and Basak, S., Surface functionalization of wool using 172nm UV excimer lamp. J. Appl. Polym., 117, 3448, 2010. 12. Basak, S., Samanta, K.K., Chattopadhyay, S.K., Pandit, P., Maiti, S., Green fire retardant finishing and combined dyeing of proteinous wool fabric. Color. Technol., 132, 135–143, 2016a. 13. Kambli, N., Basak, S., Samanta, K.K., Deshmukh, R.R., Extraction of natural cellulosic fibers from cornhusk and its physico-chemical properties. Fibers Polym., 17, 687, 2016. 14. Basak, S., Samanta, K.K., Saxena, S., Chattopadhyay, S.K., Parmar, M.S., Selfextinguishable cellulosic textile from Spinacia oleracea. Ind. J. Fiber Text. Res., 42, 215, 2017. 15. Maclaren, J.A. and Milligan, B., Wool Science: The chemical reactivity of wool fiber, Science Press, Marricksville, Australia, 1981. 16. Jocic, D., Jovancic, P., Trajkovic, R., Seles, G., Influence of a chlorination treatment on wool dyeing. Text. Res. J., 63, 619, 1993. 17. Teli, M.D., Samanta, K.K., Pandit, P., Basak, S., Chattopadhyay, S.K., Low Temperature dyeing of Silk using Atmospheric Plasma Treatment. Ind. J. Nat. Fibers, 1, 1, 2014. 18. Teli, M.D., Samanta, K.K., Pandit, P., Basak, S., Gayatri, T.N., Hydrophobic Silk Fabric using Atmospheric Pressure Plasma. Int. J. Bioresour. Sci., 2, 15, 2015. 19. Samanta, K.K., Gayatri, T.N., Saxena, S., Basak, S., Chattopadhyay, S.K., Arputharaj, A., Prasad, V., Hydrophobic functionalization of cellulosic substrates using atmospheric pressure plasma. Cellul. Chem. Technol., 50, 745, 2016. 20. Morgan, L., Tyrer, J., Kane, F., The effect of CO2 laser irradiation on surface and dyeing properties of wool for textile design. J. Laser Appl., 1, 2018, 2014. 21. Periyasamy, S., Gulrajani, M.L., Gupta, D., Preparation of a multifunctional mulberry silk fabric having hydrophobic and hydrophilic surface using VUV excimer lamp. Surf. Coat. Technol., 201, 7286, 2007. 22. Gulrajani, M.L., Gupta, D., Periyasamy, S., Muthu, S.G., Preparation and application of silver nanoparticles on silk for antimicrobial properties. J. Appl. Polym., 108, 614, 2008. 23. Basak, S. and Gupta, D., Advanced processing of woollen textile pretreated with UV excimer radiation. Manmade Text. India, 41, 204, 2013. 24. Xin, J.H., Zhu, R., Hua, J., Shen, J., Surface modification and low temperature dyeing properties of wool treated by UV radiation. Color. Technol., 118, 169, 2002. 25. Kan, C.W., Effects of laser irradiation on polyester textile properties, J. Applied Polym. Sci., 107, 3, 1584–1589, 2008.

330  Frontiers of Textile Materials 26. Deogaonkar, S.C., Wakode, P., Rawat, K.P., Electron beam irradiation post treatment for degradation of non-biodegradable contaminants in textile waste water. Radiat. Phys. Chem., 165, 108377, 2019. 27. Henniges, U., Hasani, M., Potthast, A., Westmass, G., Rosenau, T., Electron beam irradiation of cellulosic materials—Opportunities and limitations. Materials, 6, 1584, 2013. 28. Basak, S., Patil, P.G., Shaikh, A.J., Samanta, K.K., Green coconut shell extract and boric acid: new formulation for making thermally stable cellulosic paper. J. Chem. Technol. Biotechnol., 91, 2871, 2016b. 29. Basak, S., Samanta, K.K., Chattopadhyay, S.K., Narkar, R., Thermally stable cellulosic paper made using banana pseudostem sap, a wasted by product. Cellul., 22, 2767, 2015. 30. Basak, S., Samanta, K.K., Saxena, S., Chattopadhyay, S.K., Mahangade, R., Flame retardant cellulosic textile using banana pseudostem sap. Int. J. Cloth. Sci. Technol., 27, 247, 2015. 31. Basak, S., Samanta, K.K., Chattopadhyay, S.K., Narkar, R., Self-extinguishable lingocellulosic fabric by using banana pseudostem sap. Curr. Sci., 108, 372, 2015c. 32. Basak, S. and Ali, S.W., Sustainable fire retardancy of textiles using bio-­ macromolecules. Polym. Degrad. Stab., 133, 47, 2016c. 33. Samanta, K.K., Jassel, M., Agrawal, A.K., Antistatic effect of atmospheric pressure glow discharge cold plasma treatment on textile substrates. Fibers Polym., 11, 431, 2010a. 34. Samanta, K.K., Jassel, M., Agrawal, A.K., Atmospheric pressure glow discharge plasma and its applications in textile. Ind. J. Fiber Text. Res., 31, 83, 2006. 35. Teli, M.D., Samanta, K.K., Pandit, P., Basak, S., Chattopadhyay, S.K., Lowtemperature dyeing of silk fabric using atmospheric pressure helium/ nitrogen plasma. Fibers Polym., 16, 2375, 2015b. 36. Park, D.J., Lee, M.H., Yeon, I.W., Han, D.W., Choi, J.B., Kim., J.K., Hyun, S.O., Chung, K., Park, J., Sterilization of microorganisms in silk fabrics by microwave-induced argon plasma treatment at atmospheric pressure. Surf. Coat. Technol., 202, 5773, 2008. 37. Ratnapandian, S., Wang, L., Fergusson, S.M.A., Naebe, M., Effect of Atmospheric Pressure Plasma treatment on pad-dyeing of natural dyes on wool. J. Fiber Bioeng. Inf., 4, 267, 2011. 38. Samanta, K.K., Jassel, M., Agrawal, A.K., Improvement in water and oil absorbancy of the textile substrate by atmospheric pressure cold plasma treatment. Surf. Coat. Technol., 203, 1336, 2009. 39. Samanta, K.K., Jassel, M., Agrawal, A.K., Formation of nano-sized channels on polymeric substrates using atmospheric pressure glow discharge cold plasma. J. Nanotechnol. Appl., 4, 71, 2008. 40. Samanta, K.K., Joshi, A.G., Jassel, M., Agrawal, A.K., Study the hydrophobic finishing of cellulosic substrates using He/1,3 butadiene plasma at atmospheric pressure. Surf. Coat. Technol., 213, 65, 2012.

Plasma and Other Irradiation Technologies  331 41. Vinogradov, I.P. and Lunk, A., Structure and chemical composition of polymer films deposited in a dielectric barrier discharge (DBD) in Ar/fluorocarbon mixtures. Surf. Coat. Technol., 200, 660, 2005. 42. Samanta, K.K., Jassel, M., Agrawal, A.K., Atmospheric pressure plasma polymerizationof 1,3-butadiene for hydrophobic finishing of textile substrates. J. Phys. Conf. Ser., 208, 012098, 2010b. 43. Samanta, K.K., Patil, P.G., Saxena, S., Arputharaj, A., Basak, S., Gayatri, T.N., Value Added Nano-finishing of Cotton Textile using Water-free Plasma Technology. Cotton Res. J., 7, 83, 2015c. 44. Nimmanpipug, P., Lee, V.S., Janhom, S., Suanput, P., Boonyawan, D., Tashino, K., Molecular functionalization of cold plasma treated Bombyxmori silk. Macromol. Symp., 264, 107, 2008. 45. Hodak, S.K., Supasai, T., Paosawatyanyong, B., Kamlangkla, K., Pavarajarn, V., Enhancement of the hydrophobicity of silk fabrics by SF6 plasma. Appl. Sorf. Sci., 254, 4744, 2008. 46. Selli, E., Riccardi, C., Massafra, M.R., Marcandalli, B., Surface Modifications of Silk by Cold SF6 Plasma Treatment. Macromol. Chem. Phys., 202, 1672, 2001. 47. Suanpoot, P., Kueseng, K., Ortmann, S., Kaufmann, R., Umongno, C., Nimmanpipug, P., Boonyawan, D., Vilaithong, T., Surface analysis of hydrophobicity of Thai silk treated by SF6 plasma. Surf. Coat. Technol., 202, 5543, 2008. 48. Chaiwong, C., Tunma, S., Sangprasert, W., Nimmanpipug, P., Boonyawan, D., Graft polymerisation of fire retardant compound onto silk via plasma jet. Surf. Coat. Technol., 204, 2991, 2010. 49. Kale, K.H. and Palaskar, S., Atmospheric pressure plasma polymerization of hexamethyldisiloxane for imparting water repellency to cotton fabric. Text. Res. J., 81, 608, 2011. 50. McCord, M.G., Hwang, Y.J., Qiu, Y., Hughes, L.K., Bourham, M.A., Surface analysis of cotton fabrics fluorinated in radio-frequency plasma. J. Appl. Polym. Sci., 88, 2038, 2003. 51. Allan, G., Fotheringham, A., Weedall, P., The Use of Plasma and Neural Modelling to Optimise the application of a Repellent Coating to Disposable Surgical Garments. AUTEX Res. J., 2, 64, 2002. 52. Kilic, B., Cireli, A., Mutlu, M., Surface modification and characterization of cotton and polyamide fabrics by plasma polymerization of hexamethyldisilane and hexamethyldisiloxane. Int. J. Cloth. Sci. Technol., 21, 137, 2009. 53. Hocker, H., Plasma Treatment of Textile Fibers. Pure Appl. Chem., 74, 423, 2002. 54. Zawhary, M.M., Ibrahim, N.A., Eid, M.D., The impact of nitrogen plasma treatment on physical chemical and dyeing properties of wool fabric. PolymPlast Technol., 45, 1123, 2006. 55. Molina, R., Canal, C., Bertran, E., Tascon, J.M.D., Erra, P., Low Temperature plasma modified wool fabrics: Surface study by S.E.M. Current Issues on Multidisciplinary. Microsc. Res. Educ., 242, 2005.

332  Frontiers of Textile Materials 56. Kan, C.W., Chan, K., Yuen, C.W.M., A study of the Oxygen Plasma Treatment on the Serviceability of a wool fabric. Fibers Polym., 5, 213, 2004. 57. Wakida, T., Tokino, S., Niu, S., Kawamura, H., Sato, Y., Lee, M., Uchiyama, M., Inagaki, H., Characterization of wool and polyethylene terephthalate fabrics and film treated with low temperature plasma under atmospheric pressure. Text. Res. J., 63, 433, 1993. 58. Bhat, N.V., Netravali, A.N., Gore, A.V., Sathianarayanan, M.P., Arolkar, G.A., Deshmukh, R.R., Surface modification of cotton fabrics using plasma technology. Text. Res. J., 81, 1014, 2011. 59. Hegemann, D., Mokbul Hossain, M., Balazs, D.J., Nanostructured plasma coatings to obtain multifunctional textile surfaces. Prog. Org. Coat., 58, 237, 2007. 60. Labay, C., Canal, J.M., Canal, C., Relevance of Surface Modification of Polyamide 6.6 Fibers by Air Plasma Treatment on the Release of Caffeine. Plasma Process. Polym., 9, 165, 2012. 61. Gotoh, K. and Yasukawa, A., Atmospheric pressure plasma modification of polyester fabric for improvement of textile specific properties. Text. Res. J., 81, 368, 2011. 62. Hildegard, S.S., Plasma Pre-treatment of Textiles for Improvement of Dyeing Processes. Int. Dyer, 188, 20, 2003. 63. Lee, H.R., Kim, D.J., Lee, K.H., Anti-reflective coating for the deep coloring of PET fabrics using an atmospheric pressure plasma technique, Proceedings of the 7th International Conference on Plasma Surface Engineering. Surf. Coat. Technol., 142–144, 468–473, 2001. 64. Ferrero, F., Tonin, C., Peila, R., Pollone, F.R., Improving the dyeability of synthetic fabrics with basic dyes using in situ plasma polymerization of acrylic acid. Color. Technol., 120, 30, 2004. 65. Gage, L.P. and Manning, R.F., Internal structure of the silk fibroin gene of Bombyxmori.I The fibroin gene consists of a homogeneous alternating array of repetitious crystalline and amorphous coding sequences. J. Biol. Chem., 255, 9444, 1980. 66. Iriyama, Y., Mochizuki, T., Watamabe, M., Utada, M., Preparation of silk film and its plasma treatment for better dyeability. J. Photopolym. Sci. Tec., 16, 75, 2003. 67. Teli, M.D., Samanta, K.K., Pandit, P., Optimization of Plasma Modification for Low Temperature Dyeing of Silk Fabric, in: Biopolym. Biomater., pp. 127– 145, Apple Academy Press and CRC Press, USA 2018. 68. Karahan, H.A., Ozdogan, E., Demir, A., Kocum, I.C., Oktem, T., Ayhan, H., Effects of Atmospheric Pressure Plasma Treatments on Some Physical Properties of Wool Fiber. Text. Res. J., 79, 14, 1260–1265, 2009. 69. Kan, C.W., Effect of low temperature plasma on different wool dyeing systems. AUTEX Res. J., 8, 132, 2007. 70. Sun, D. and Stylios, G.K., Effect of low temperature plasma treatment on the scouring and dyeing of natural fabrics. Text. Res. J., 74, 9, 751, 2004.

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14 Bio-Mordants in Conjunction With Sustainable Radiation Tools for Modification of Dyeing of Natural Fibers Shahid Adeel1*, Shumaila Kiran2†, Tanvir Ahmad3, Noman Habib4, Kinza Tariq2 and Muhammad Hussaan4 Department of Chemistry, Govt. College University, Faisalabad, Pakistan Department of Applied Chemistry Govt. College University, Faisalabad, Pakistan 3 Department of Statistics, Govt. College University, Faisalabad, Pakistan 4 Deaprtment of Botany, Govt. College University, Faisalabad, Pakistan 1

2

Abstract

Day by day acuteness in the alarming situation of synthetic dyes and their intermediates used during their synthetics waste out, such effluent load, that the world is now concerned about health of globe. So the sustainable products having ayuervedic and remedial nature in applied fields are nowadays demand of global community due to spread of awareness by many agencies such as UNESCO, WFO, FAO, EPA, etc., about hazardous and carcinogenic effects of synthetic dyed products. Of these green and sustainable products, natural dyes and pigments have been found as niche sources in applied fields for healthy and clean global atmosphere. However, due to some problems associated with natural colorants, new methodologies on account of cost, time, and labor effectiveness have been introduced in isolation of colorant, surface modification of wool and silk fabric for firm fixation as well as introduction of bio anchors for development of new shades. Current chapter will deal with exploration of new plant sources, i.e., coconut coir (Cocos nucifera) and Arjun (Terminalia arjuna) for coloration of silk and wool using microwave and ultrasonic treatment. The addition of bio-mordants instead of chemical alternatives, having wonderful therapeutic and ayurvedic nature, will also be discussed for exploring the news shades and improvement in fastness properties. Hopefully this chapter will be handy for the academician, *Corresponding author: [email protected] † Corresponding author: [email protected] Mohd Shabbir, Shakeel Ahmed, and Javed N. Sheikh (eds.) Frontiers of Textile Materials: Polymers, Nanomaterials, Enzymes, and Advanced Modification Techniques, (335–348) © 2020 Scrivener Publishing LLC

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336  Frontiers of Textile Materials researchers, and natural dyers who are utilizing conventional tools and will catch attention of users of these modern methods for isolation of natural dyes and utilization of bio-mordants to make the process more green, sustainable, and therapeutic. Keywords:  Bio-mordants, coconut, microwave radiation, wool, silk, ultrasonic radiation

14.1 Natural Dyes These days’ synthetic dyes are heavily used in textiles and industries while they have many problems like waste disposal. Other problems include they are not biodegradable, have water pollution, environment unfriendly, and carcinogenic. This situation leads to choose natural dyes as a reasonable replacement or solution, although we know that they are not successful in commercial [1]. Natural dyes are biodegradable, fairly less harmful, ecofriendly, produces highly attractive and smooth shades [2]. Natural colorants come from plants or animals, used in industries that are producing different products of human use [3].

14.2 Health and Environmental Aspects With the general public’s more suitable attention to eco-safety and fitness worries, environmentally benignant and non-toxic bio-resource products are regaining reputation in exclusive spheres of our lives. Natural dyes, received from flora, insects/animals and minerals, are renewable and sustainable bio-aid merchandise with mini mum environmental impact and known on account that antiquity for his or her use, now not simplest in color of textiles [4] but additionally as food substances [5] and cosmetics [6]. Amidst growing environmental and health worries green non-poisonous herbal dyes reemerged as ability feasible ‘Green chemistry’ option as an alternative/co-partner to some extent to synthetic dyes [7, 8]. Recent resurgence in research and improvement on herbal dye production and alertness is located because of growing recognition of greater herbal lifestyle based on evidently sustainable goods [9].

14.3 Isolation Process First step to obtained natural dyes or colorants is to extract it from natural source, which have most importance, because after this can be treated in

Bio-Mordants and Dyeing of Natural Fibers  337 textile to get or achieve desired colors and properties like anti-microbial. Additionally, for optimization of extraction parameters and getting a standard extraction method for specific natural source are important because it affects the product price and end-product quality [10]. There are some conventional and modern methods or techniques of extraction which are mentioned below:

14.3.1 Conventional Methods Different conventional methods such as heating soaking, stirring, etc. are being employed in isolation of natural products. Although they are viable to employ but are not as effective as modern methods.

14.3.2 Modern Methods • • • •

Ultrasonic Extraction Microwave Extraction Gamma Extraction Plasma Extraction

14.4 Role of US and MW in Isolation Microwave like other waves is an electromagnetic radiation. The frequency of microwave is from 103 MHz to 106 MHz. The microwave heat is very fast technique because of no loss of heat and are safe to use. Microwave has many advantages such as low cost, increase of color fastness, dyed uptake and consumed less energy, power, and time. It was observed that by increasing the power up to 700 increased the rate of extraction and give better yield. Microwave not only enhanced production speed but also penetrated to the dyed material and ruptured the cell wall by which coloring components can easily come out. Microwave provided heat uniformly throughout the material and conventional or traditional heating only heated the surface of material. Microwaves are the power sources of non-contact heating and in the microwave field the substance that have permanent dipoles to rotate [11]. In 1952 1st citation of ultrasonic assisted extraction showed the boiling extraction can be compared or likewise to ultrasonic extraction. After that many papers published on this modern extraction method. Hops, 30–40%, were saved by using ultrasonic extraction method for beer production in paper of 1952. I am notifying that by using high frequency of ultrasonic,

338  Frontiers of Textile Materials degradation of herb molecules or constituents reduced but not significance increase in yield [12].

14.5 Fabric Chemistry Wool is the semi-crystalline, proteinaceous material polymer related with group of proteins called α-keratins [13]. Wool is normally versatile, fire resistor, great warmth protector, and hygroscopic in nature. The essential building squares of α-keratin protein are 18 diverse α-amino acids, for example, cysteine, lysine, arginine, glutamic corrosive, and aspartic corrosive, having general equation H2N–CH(R)–COOH. Silk is the insect fiber which is obtained from silkworm that spins around itself to form a cocoon. Natural silk is synthesized by silkworm [14]. Natural or raw silk includes three to four components in its composition, like fibroin and sericine, respectively 62.5–67% and 22–25% in amount, other compounds includes mineral salts and water. Fibroin is a major part forms beta plated sheets and made up of two components Gly–Ser–Gly–Ala and amino acid. Cotton fiber: An elongated (30 mm) plant cell with excessive cellulose (95%). Cotton cellulose: molecule is 10 µm long, 0.4 nm thick, 0.8 nm wide [15].

14.6 Shade Development Process Mordants are those substances which show attraction for both textile fibers and dye acting as bridge. Mordants are used for those dyes that do not have affinity for fibers. Mordants can also be used for those dyes that have affinity for fibers. In that case they form an insoluble complex within the fibers and increase their fastness properties and colors. In natural dyeing mordanting process to get the great attraction toward textile industry, some mordants are used for colorants such as metal salt or other chemicals or compounds. There are three types of mordants on the basis of application time [16, 17] • Meta-mordanting • Pre-mordanting • Post-mordanting As it was of pre-mordanting textures materials treated with mordants before kicking the bucket procedure. This strategy gives unique, popular, agreeable time and position on material to join to the mordants. If there should be an occurrence of meta-mordanting or synchronous mordanting

Bio-Mordants and Dyeing of Natural Fibers  339 the two mordants and colors are break up into color shower include a period for coloring. In post-mordanting process right off the bat colorants are connected to the uncovered material surface and afterward mordanting process is completed. Generally this procedure connected upgrades the shade run with stringent complexation with color atom on the surface of textures. This strategy may not be an appropriate technique to build the shading speed [18].

14.6.1 Chemical Mordant Some of mostly used Chemical mordant are alum (potassium aluminum sulfate), iron (ferrous sulfate), nickel (nickel chloride), chromium (potassium dichromate), copper (copper sulfate), and tannic acid [19]. Chemical mordant 1—Alum 2—Iron 3—Nickel 4—Chromium 5—Copper 6—Tannic acid

14.6.2 Bio-Mordant Bio-mordant include Acacia, Pomegranate, Henna, and Turmeric and the process of applying is the same as chemical mordanting. Turmeric gives good quality of shades and color strength. Bio-mordant 1—Turmeric 2—Pomegrante 3—Henna 4—Accacia

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14.7 Arjun T. arjuna is a medicinal plant used in making of or as a medicine to cure for many deteriorating diseases [20]. By using phytochemical analysis we come to know that a large no. of phenolic compounds, phytosterol, flavonoids, lactones, and glycosides present in the methanol extract of T. arjuna bark. As there is huge amount of flavonoid compounds showed that T. arjuna has properties like antioxidant and anti-microbial. So other results also showed that and support the common view that T. arjuna is useful and promising source of natural useful therapeutic agents [21].

14.8 Neem According to its activities and medicinal properties, it is called by different names like, nature’s drug store, divine tree, and village dispensary [2]. Study suggested a number of active constituents might be present in the neem bark extract to control pathogens.

14.9 Coconut The coconut is a functional food because it provides health benefits beyond its nutritional content Cocos nucifera is a plant that has low toxicity and very much pharmacological effects. As the plant have use in food industry so medicinal use is environmental appeal, so wasted or discarded parts of plants can be used which reduced waste pollution. Different parts of plants have different pharmacological effects. Coconut water and endocarp constituents have mush ability of antioxidant activity. Also coconut water is seems to be protective for heart and kidney. Further, fibers have the properties like ant parasitic, anti-inflammatory, and antibacterial [22].

14.10 Harmal The extracts of many medicinal plants are used for their antifungal, antiviral and antibacterial in many areas of the earth [23, 24]. The property of plants which is called antibacterial is not much understood yet and still in debates [25]. The results showed that the extracts of P. harmala have anti-bacterial activity property in different magnitudes, which is dependent of method of extraction like alkaloids, aqueous, and flavonoids

Bio-Mordants and Dyeing of Natural Fibers  341 extracts). The results of this study showed P. harmala as a potential source of antimicrobial drug against the four urinary pathogens tested. This is particularly important in the fight against the recent resistant organisms with multiple drugs.

14.11 Recent Advances Natural dye is colored substance which can be extracted from organic compounds only and used in coloring of many things like cosmetics, medicine, etc. Natural dyes have no carcinogenic effects but also have health benefits. Natural dyes have elegant coloring ability on all types of fabrics. Coconut husk powder can be effectively used to dye cotton with good results. For dyeing, optimal conditions were 80°C with concentration 4%, 6%, and 8% shades of dye at 45°C, using eco-friendly mordants alum and vinegar. The light fastness, rubbing, and washing and properties of samples that were dyed tested with gray scale and found to be satisfactory. Hence, it indicates that coconut fiber lead to good dye ability of cotton fabrics [26]. In this study natural colorant was extracted from coconut husk (Cocos nucifera L.) through a fractional factorial design of experiment with Taguchi’s orthogonal arrays and applied to a silk fabric by a dying process. UV–VIS spectrophotometry was performed on the extracts with a series of extraction experiments which were performed to obtain optimum condition of a 1:20 liquor ratio, 30 min extraction time, and 70°C temperature. Dyed silk fabrics showed coral pink color and showed acceptable colorfastness to washing and K/S values. They also showed more soft and shiny color than that of the silk fabrics dyed with synthetic dyes. It can be concluded that the natural dye from coconut husk can be applied as commercial natural dyestuff for silk products [27]. Silk fabric was dyed with vegetable dye using green coconut shell extract. Dyeing of silk fabric showed appreciable depth of color and good fastness (light and wash) properties. In order to check the dyeing characteristics different parameters such as dyeing time, pH of dye bath and various mordants were used. A little bit change in above mentioned experimental parameters gave us different shades and good quality of fastness. But in case of tin and aluminum mordant, the tone of dyeing increased from light to medium and medium to heavy shades, bearing fair to good fastness properties (light and wash). According to the experimental values, optimum dyeing values of pH, time, and dye concentration were 4.0–4.5, 1 h, and 3.0–3.5, respectively. Thus we can utilize waste green coconut-shell as a cheap source of vegetable dye in silk fabric [28]. In this study by using

342  Frontiers of Textile Materials cochineal and gall oak shellac extracts, silk fabrics were dyed. The mordant used was alum. After this, by using various concentrations of colorants optimum dyeing conditions were determined. All the post-mordanted and dyed samples were passed through reserved phase high-performance liquid chromatography (RP-HPLC) with the diode-array detection (DAD) technique, for the identification of the constituents of dyes. The color fastness and characteristics values of light, perspiration, washing and rubbing were examined. At the end we can say that using mixture of these natural dyes gives good color fastness properties [29]. Worldwide, the demand of natural dyes has highly increased because of the harmful properties of synthetic dyes. In present study eco-friendly extraction of dye from Arjun bark for textile has taken place, with natural brown color. Both the plant powder and silk fabric were treated with microwave radiation for up to 6 min. Dyeing was performed by using different extracts of Arjun bark at various variations onto silk fabric (irradiated and un-irradiated). One bio and one chemical mordant were used to dye for optimum conditions to make process more sustainable. The results determined the condition of 8 g of powder in acidified methanol extract with irradiated silk at 65 min and 65°C in the presence of Na2SO4 using dye bath of pH 1. This gave higher coloring strength. By using 1% of iron and aluminum, 1% of pomegranate and turmeric as chemical mordant and bio-mordant respectively, obtained improved shades and fastness. At the end we come to know that Arjun bark is a potential source of coloring as well as microwave radiations improved color efficiency [30]. Nowadays, in global community, dyeing of natural fabrics with natural dyes under the influence of modern, eco-friendly techniques such as gamma, ultrasonic, and microwave are gaining popularity due to the sustainable and therapeutic nature of dye yielding plants. In current study, neem was used as a source of tannin for dyeing silk fabric, extracted in methanol media under the influence of Ultrasonic treatment for 30 min (RE 30 min). Dyeing conditions were 75°C for 65 min. In order to improve shades, chemical and bio-mordant such as henna, turmeric, pomegranate, and acacia were applied under optimal condition. It was observed that methanol extract with pH 5, obtained 8 g powder after 30 min ultrasonic treatment, dyed for 65 min at 75°C gave high color strength. Also bio-mordanting gave good color characteristics, whereas ultrasonic method is cost effective, ecofriendly, time and labor effective [31]. Due to environmental pollution researchers, industrialists and traders moving toward natural dyes instead of synthetic dyes. Natural dyes are eco-friendly and sustainable. In current study with the treatment of ultrasonic, silk fabrics were dyed by using Arjun bark which has reddish brown

Bio-Mordants and Dyeing of Natural Fibers  343 natural colorant. Extraction carried out in different media such as organic acidic and basic, then silk fabrics irradiated for 15, 30, 45, and 60 min. Good shades strength were obtained, they use pH 3, 6 g powder irradiated for 65 min at 65°C using salt concentration 3 g/100 mL. Al, 5%, and 9% of Fe were used as pre- and post-mordant and increased the color characteristics. For excellent color shading 9% of turmeric and pomegranate were used. Hence it is proved that Arjun bark is excellent source of colorant [32]. For making textile dyeing ecofriendly natural dyes gaining popularity, on the other hand microwave treatment make it more green, time effective and Eco label. In this study, extract of safflower used to dye silk fabric under the influence of microwave, followed by treatment or dyeing of bio- and chemical mordanting. It is found that extract irradiated for 3 min with un-irradiated silk and 60 min dyeing of un-irradiated silk using acidic extract of safflower gives high color and darker shades. Further lawsone from bio-mordant gives color strength from good to excellent. At the end it is concluded that microwave treatment is not only ecofriendly, time effective but also gives excellent shades [33]. For traders, consumers, and researchers natural dyeing is always a new task to improve color strength and green textile. In this study researchers used harmal seeds which have natural colorant (yellowish red) to dye cotton fabric under the influence of Microwave followed by pre and post-mordanting. Results showed that extract of 8 g powder in acidified methanol and irradiated for 4 min. It is also concluded that bio-mordant gives good shades than chemical mordant and makes the process greener, herbal, as well as ecofriendly. Al, 1%, and 7% of Fe as pre- and postmordanting, respectively, improved the color strength than other mordants used. It can be concluded that harmal is a good dye yielding plant and microwave treatment is ecofriendly [34]. In this study, for dyeing wool fabric under the influence of microwave treatment Arjun bark used as a dye. Different extract made in different media used to dye wool fabric and irradiated extract for up to 6 min. Results showed that 4 g of powder in acidified methanol, 3 pH, irradiated for 4 min gives high color strength. FTIR and SEM analysis showed morphological changes but no chemical changes. Turmeric and iron gives good fastness properties. It is concluded that dyeing with Arjun under the influence of microwave improved functional behavior [35]. Due to environment friendly behavior natural dyes are gaining importance. In the current study carminic acid, which is a natural dye, cochineal based, was used to dye wool with treatment of microwave radiation. Extracts made in different media were used to irradiate for up to 6 min. pH and dyeing temperature were optimized, by using parameters followed by bio- and chemical mordanting. It is found that

344  Frontiers of Textile Materials un-irradiated wool with radiated extract for 5 min gives dark shades. By using ISO standard method, properties discovered that 3% of pomegranate and 5% of henna gives high color strength other than chemical mordant. It is proved that microwave increase the color character and dyeing behavior [36]. In this work, Madder plant was used to dye wool fabric as natural colorant with microwave treatment. It comes to know to know that dyeing properties like pH value, dyeing time, temperature, and dye concentration were affected. After dyeing fastness properties such as washing, light, rubbing and perspiration were determined. These all results suggested that microwave treatment is much better and affective then other conventional method. It is found that untreated samples have fewer values than treated fabrics. Results show good color characteristics. So, at the end we can say that we should promote these ecofriendly dye techniques [37]. These days bio-mordanting is gaining importance due to their herbal and ecofriendly nature. In this study, tannin which is a natural colorant isolated from neem bark and used to dye silk fabric with microwave treatment also followed by mordanting. In this regard extract of neem bark prepared in different media and dyeing parameters were optimized, with conditions such as microwave treatment 2 min, pH 2, acidified methanol extract in 6 g powder, 75°C temperature, and 65 min dyeing of irradiated silk gives good color shades. Bio-mordant like henna, pomegranate, acacia, and turmeric make the process green. It can be concluded that isolation of tannin from neem as well increased color strength [38].

Acknowledgments The authors are extremely grateful to UNESCO for providing the funding for the work presented in this chapter through project PhosAgro/ UNESCO/IUPAC/GCUF Project No. 128.

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Index α-Keratin, 338 2-methacryloyloxyethyl phosphorylcholine monomer, 78 Accacia, 339, 342, 344 Acoustic wave filters, 142 Acrylic esters, 74 Acrylic fiber, 223–224, 227, 229–230, 232, 236, 238, 240–241, 245–246, 248, 271 Acrylic polymers, 74 Agar diffusion test method, 145 Air jet knife, 69 Alcohol, ethanol, 219, 225–227, 230, 255, 258–259 polyol, 219, 257, 276 Alum, 339, 341, 342 Ammonium salt of melamine hexa(methylphosphonic acid) (AMHMPA), 78 Antibacterial, 122, 126–130, 227–228, 248, 267, 269 Antibacterial function, 81–82 Antibacterial monomers, 82 Antibacterial textile, 136 Anti-creases, 222, 278 Anti-odor, 87, 91, 101, 109 Application based on properties of textile material, 179 Application in textile industry, 181 Application of textiles nanomaterials, 179 Aramid fiber, 45–46

Arginine, 338 Arjun (Terminalia arjuna), 335, 340, 342, 343 Aspartic corrosive, 338 Attachment, 91–97, 100–108 Azobis-isobutyronitrile, 73, 78 Bast fiber, 26 Biomaterials, 198 Bio-mordant, 335, 339, 342–344 Bonds, covalent, 224, 229–230, 247–249, 262, 275–276, 278 electrostatic/ionic, 223, 238, 240, 245–247, 254, 265, 274 hydrogen, 231, 247, 254, 257, 259, 265, 275–276, 278 Boron-nitrogen, 78 Cellulose, 24, 190–198 Characterization, 171 Characterization of textile nanomaterials by x-Ray, 176 Chemical image, 318 Chemical modification, 91, 109 Chemical mordant, 339, 342, 343 Chitosan, 118–120, 127–131 bulk chitosan, 128, 129 carboxy methyl chitosan, 127 chitosan idoacetamide, 119–120, 127, 128 chitosan nanofiber, 119, 127 chitosan nanoparticle, 128–130 thiol-chitosan, 119, 127, 128

349

350  Index Chitosan product, alkyl chitosan, 266, 269, 272 chitosan, 219, 232–234, 237–238, 240–241, 244–249, 262–263, 265–273, 275–278 triethyl chitosan, 219, 272–273 Chromium, 339 Coating materials, 73–77 polyacrylics (PA), 74 polyurethane (PU), 75, 77 polyvinylchloride (PVC), 74 Coconut coir (Cocos nucifera), 335, 339, 340 Collagen, 190, 194–199 Coloration, 320 Colorimetric, 222, 229, 249, 257, 265 Colorimetry, color intensity (K/S), 222, 223, 229–231, 238, 240–241, 244, 247–249, 254, 258–259, 265–266, 269–270, 274–275 luminosity, 255 Copper, 339 Cotton, 25 Cotton fiber, 338, 341, 343 Crosslinking, 220, 228, 267, 278 Crosslinking agent, 91–96, 105 Cyclic oligosaccharide, 87–88 Cyclodextrins, α-cyclodextrins, 88 β-cyclodextrin (β-CD), 87–109 γ-cyclodextrins, 88 Cysteine, 338 Different methood of synthesis, 169–170 Dip coating, 63–64 Dopamine polymerization, 81 Drying, 123–124, 126 Dye, acid dye, 231, 240–241, 248, 255, 259, 265, 269, 274–277 anionic dye, 229, 244 cationic dye, 254, 256, 275 direct dye, 247, 258–259, 275–276

disperse dye, 256 reactive dye, 229, 242–243, 247, 259 vat dye, 259 Dyeing, 88, 91, 98, 100, 102, 105–107, 219, 223, 229–230, 232, 238, 239–249, 253–255, 258–260, 264–265, 269, 273–279 E-beam irradiator dyeing, 296 Efficiency, 206, 208–210, 212 Electrical energy, 204, 205 Electrode substrate, 204, 206, 209, 212 Electrofluidodynamic treatment technology, 72 Electron beam irradiation, 312, 327 Electronic microscopy (SEM), 219, 222, 228, 248, 257 Electronics, 7, 203, 212, 213 Electrospinning, 119, 123–124, 126, 128–129, 139 Emulsion polymerization, 74 Energy harvesting, 190, 191 Enzymes, 4, 5 Escherichia coli bacteria, 82 E-textiles, 77 Ethylenediamine, 231–232, 250–251, 252, 255–256, 267, 279 Extrusion coating, 65 Fabric, 204–206, 208–210, 213 Fabrication, 203, 205, 209 Fiber, 23, 117–119, 122–125 cotton, 219–220, 266–270, 272–279 Melana (PAN-M), 223–224, 230–243, 245–248 polyacrilonitrile (PAN), 223–228, 244–245, 248 recycled PET, 250–251, 252, 256–257, 259 virgin PET, 250–251, 253, 255, 257, 260 cotton-fiber, 126–127

Index  351 micro-fiber, 126 nanfiber, 119, 122–124, 125–129 polymeric fiber, 125 Fibroin, 28 Filament, 28 Fillers, 73 Fixatives, 73 Flame retardancy, 147 Flame retardants, 73, 105, 109 Flame-retardant finishes, 77–79 Flexible, 203–208, 210, 212 Fluorocarbon, 79 Fragrance release, 101, 109 FTIR, 154, 161, 227, 229, 232, 248, 252–253, 257, 262, 264, 272 FTIR-analysis, 343 Functinal modification, 135 Functional finishing, 90 Functional properties, 87, 89, 100 Functionalization, 220, 223–224, 227–229, 231, 233–236, 238, 240–241, 249, 249–253, 255, 258, 274, 277 functionality, 219, 257, 278 multifunctionality, 219 multifunctionalization, 221–223, 225, 235, 245, 247, 248–249, 261, 267, 275, 278 Gamma irradiation dyeing, 295 Glass, 203, 204 Glumatic corrosive, 338 Grafting, 219–220, 222, 244, 247–250, 255, 257–258, 260–273, 278 Graft-on-graft, 267 Gravure roll coating, 64–65 Green energy, 191 Harmal, 339, 343, 344 Hemicellulose, 24 Henna, 339, 342, 344 Host–guest, 89 Hydrazine, 230–232 Hydrogels, 124–128, 131

Hydrophilicity, 219, 222, 230, 267, 268–269, 275 Hydrophobia, 272, 276 Hydrophobic agents, 73 Hydrophobic textile, 316 Hydroxylamine, 219, 224, 226, 228, 233, 235–236, 241, 247–249 Impermeability, 79 Inclusion complex, 90, 92, 100–105 Integrated, 189, 191, 199 Introduction of textile nanomaterials, 167 Ion implantation technology dyeing, 291, 296 Iron, 339, 342 Jute, 26 Keratin, 26–27 Kevlar fiber, 46 Kiss roll coating, 64 Knife coating, 66–71 drying, 67–68 knife use technologies, 69 thickness, 67 type of, 70–71 type of knife, 68 viscosity, 67 Laser irradiation, 326 Laser technology dyeing, 296 Light absorber, 206 Liquid absorbency, 320 Lycra, 53 Lysine, 338 Magneseum oxide nanoparticles, 144 MAPbI3, 206, 208 Mass peak, 317 Methacrylic acid, 74

352  Index Microscopic characterization of textile nanomaterials, 172–174 Microwave treatment, 337, 342, 343, 344 Modacrylic fiber, 52 Monochlorotriazinyl-β-cyclodextrin (MCT-β-CD), 219, 244–245, 248–249, 260, 262, 264, 266–270, 275, 277–279 N-acylation, 233–235, 241, 250 Nanogenerator, 189–198 Nanomaterials, 3, 4, 204 Nanoparticles, 118–122, 124–125, 127–130, 158, 161, 163, 213 metal nanoparticles, 118 silver nanoparticles, 120, 121 TiO2 nanoparticles, 121, 122 ZnO nanoparticles, 125 Nanotechnology, 136, 204 Neem, 339, 344 Nickle, 339 Nomenclature of nylon fiber, 44 Nomex fiber, 46 Nylon 11, 43 Nylon 12, 43 Nylon 4, 43 Nylon 6, 42 Nylon 6.10, 43 Nylon 6.6, 15, 42 Nylon 7, 43 OES spectrum, 315 Optical properties of plasma, 314 Ozone technology dyeing, 294 Padding method, 79 Pad-dry-cure, 221, 261–262, 267, 275, 277, 279 PDMS, 80 Perovskite solar cells, 206, 209, 212 Phosphor, 78 Photodetectors, 142 Photovoltaic, 204–206, 213

Piezoelectric, 189–198 Pigments, 73 Plasma, 6, 219–220, 250, 261–269, 312, 314, 316, 317 Plasma technology dyeing, 295 Plasma treatment technology, 71–72 Poly vinyl chloride, dyeing of PVC fiber, 39 manufacturing process of PVC polymer, 38 properties of PVC polymer, 40 spinning of PVC fiber, 39 types of PVC fiber, 39 Poly vinylidene chloride, 40 Polyacrylate (PA), 73, 74 Polyacrylonitrile, dyeing of acrylic fiber, 51 manufacturing process of PAN polymer, 51 PAN polymer, 50 properties of PAN polymer, 51 spinning of PAN fiber, 51 uses of PAN fiber, 52 Polyamide, aliphatic polyamide, 41 aromatic polyamide, 42, 45 dyeing of polyamide fiber, 44 properties of polyamide fiber, 44 semi-aromatic polyamide, 41 spinning of polyamide fiber, 44 uses of polyamide fiber, 45 Polycarboxylic acid, 92, 94 Polycinyl alcohal, 119 Polydopamine (PDA), 82 Polyester, 16, 118, 125, 128–130 Polyethylene, dyeing of polyethylene fiber, 32 manufacturing process of polyethylene polymer, 30 properties of polyethylene polymer, 33 spinning of polyethylene fiber, 32 types of polyethylene polymer, 30

Index  353 Polyethylene glycol, 120 Polyethylene terephthalate, dyeing of PET fiber, 49 manufacturing process of PET polymer, 48 PET polymer, 47 properties of PET polymer, 50 spinning of PET fiber, 49 Polyethylene terephthalate (PET), 73 Polymer, 2, 13–18 Polymer coating methods, 63–71 dip coating, 63–64 gravure roll coating, 64–65 kiss roll coating, 64 knife coating, 66–71 powder coating, 65 slot die or extrusion coating, 65 transfer coating, 64 Polymer coatings, new functionalities of, 77–82 antibacterial function, 81–82 application in smart textile, 77 flame-retardant finishes, 77–79 water repellence, 79–80 Polymer coatings, new technologies in, 71–73 electrofluidodynamic treatment technology, 72 plasma treatment technology, 71–72 supercritical carbon dioxide-based method technology, 72 Polymer nanocomposites, 147 Polymerization, chain polymerization, 19 coordination polymerization, 20 free radical polymerization, 19 ionic polymerization, 20 polyaddition polymerization, 22 polycondensation polymerization, 22 ring-opening polymerization, 23 step polymerization, 21 Polyols, 75

Polypropylene, dyeing of polypropylene polymer, 35 manufacturing process of polypropylene polymer, 35 PP, 33–34 properties of polypropylene polymer, 35 spinning of polypropylene polymer, 35 uses of polypropylene fiber, 36 Polytetrafluoro, manufacturing process of PTFE polymer, 37 properties of PTFE polymer, 37 PTFE, 36 spinning of PTFE fiber, 37 uses of PTFE fiber, 38 Polyurethane (PU), 52, 53, 73, 75, 77 Polyvinly alcohol, manufacturing process of PVA polymer, 55 properties of PVA polymer, 55 PVA polymer, 54 spinning of PVA fiber, 55 uses of PVA fiber, 56 Polyvinyl alcohol (PVA), 255, 257–259, 261 Polyvinyl chloride (PVC), 73–74 Pomegrante, 339, 342, 343, 344 POSS-based polymers, 79 Powder coating, 65 Preserving agents, 73 Printing, 105–107 Properties of spandex fiber, 53 Protein, 26–27 Protonation, 229, 238, 240–241, 245–246, 265, 273, 275 Radiations, 6 Saponification, 219, 222, 227, 232–235, 248, 250–256, 258–260 Self-cleaning effect, 79 SEM, 343

354  Index Shubha, 78 Silica, 80 Silicone, 73, 79 Silk, 28, 197, 198, 322 Silver nanoparticles, 81–82, 139–141 Silver nanowires (AgNW), 77 Slot die coating, 65 Smart textiles, 77, 189, 190 Sodium alginate, 56 Sodium dodecylbenzenesulfonic acid salt, 78 Softeners, 73 Solar cells, 203–212 Solar panels, 204 Sonochemical preparation, 138 Spandex fiber, elastomeric fiber, 52 Spectroscopic characterization of textile nanomaterials, 175 Spectroscopy, 219, 221–222, 267 Spinning of spandex fiber, 53 Stain repellence, 148 Staphylococcus aureus bacteria, 82 Starch, 56 Styrene-butadiene-styrene polymer, 77 Supercritical carbon dioxide dyeing, 296 Supercritical carbon dioxide-based method technology, 72 Superhydrophobia, 79 Surface chemistry, 317 Synthesis, 117, 119–121,123, 126 Synthesis of textiles nanomaterials, 168 Tannic acid, 339 Tetrol, 219, 255, 258, 262, 267, 275–277 Tetronic 701, 219, 255, 257, 262–264, 266–269, 275–278 Textile structure, 189, 190 Textiles, 1, 117–119, 122–126, 128, 203–206, 210, 212 Textiles, functionalization of, 62–82 coating materials, 73–77 polymer coating, 60–61

polymer coating methods, 63–71 polymer coatings, new functionalities of, 77–82 polymer coatings, new technologies in, 71–73 Thermogravimetric, 219, 222, 257, 279 Thickeners, 73 TiO2, 158, 159 Titanium dioxide nanoparticle, 144 Transfer coating, 64 Treatment, chemical treatment, 219–220, 223, 261 pre-treatment, 231–232, 262 Tumeric, 339, 342–344 Ultrasonic extraction method, 337, 342 Ultrasound technology dyeing, 293 Urea, 224, 230, 232, 278 Uses of spandex fiber, 54 UV irradiation, 311, 325 UV protection, 154, 155, 158 UV-blocking, 142 Viscose, 15 Wastewater treatment, 105, 108 Water repellence properties, 79–80 Wearable textiles, 190, 191, 199 Weaving, 122–124, 126 Wireless data transmission, 147 Wool, 27, 324 Wrinkle, 222, 264, 269, 272, 275, 277–279 Wrinkle-freeness, 148 XRD, 154, 161 Yarn fabrics, 74 Zinc oxide nanoparticles, 143 ZnO, 153, 154, 156, 157

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