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Handbook of Engineering and Specialty Thermoplastics

Scrivener Publishing 3 Winter Street, Suite 3

Salem, MA 01970

Scrivener Publishing Collections Editors

James E. R. Couper Richard Erdlac Norman Lieberman W. Kent Muhlbauer S. A. Sherif

Ken Dragoon Rafiq Islam Peter Martin Andrew Y. С Nee James G. Speight

Publishers at Scrivener Martin Scrivener (martin@scrivenerpublishing.com)

Phillip Carmical (pcarmical@scrivenerpublishing.com)

Handbook of Engineering

and Specialty Thermoplastics

Volume 4 Nylons

Edited by Sabu Thomas and Visakh P.M.

Scrivener

WILEY

Copyright © 2012 by Scrivener Publishing LLC. All rights reserved.

Co-published by John Wiley & Sons, Inc. Hoboken, New Jersey, and Scrivener Publishing LLC, Salem, Massachusetts. Published simultaneously in Canada.

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Cover design by Russell Richardson

Library of Congress Cataloging-in-Publication Data:

ISBN 978-0-470-63925-2

Printed in the United States of America

10 9 8 7 6 5 4 3 2 1

Contents

List of Contributors xi

1. Engineering and Specialty Thermoplastics: Nylons 1

2.

Visakh. P. M and Sabu Thomas 1.1 Polyamide-imides 1.2 Polyetherimide (PEI) 1.3 Poly(Ether-Block- Amide) 1.4 Aromatic Polyamides: 1.5 Polyaniline 1.6 Polyimides 1.7 New Challenges and Opportunities References

Polyamide Imide Zulkifli Ahmad 2.1 Introduction and History 2.2 Polymerization 2.3 Properties

2.3.1 Solubility 2.3.2 Crystallinity 2.3.3 Thermal 2.3.4 Mechanical 2.3.5 Opto-electronic 2.3.6 Hydrogen bonding

2.4 Processing 2.5 Applications

2.5.1 Membrane Material 2.5.2 Coatings 2.5.3 Electronic 2.5.4 Optical

2.6 Recent Developments on Blends and Composites 2.6.1 Blends 2.6.2 Composites

2.7 Conclusions References

1 2 2 3 5 6 8 9

11

11 13 19 19 19 22 24 25 26 27 30 30 31 32 33 33 33 34 38 38

V

vi CONTENTS

Polyphthalamides /. I. Iribarren, С. Aleman, J. Puiggali 3.1 Introduction and History 3.2 Polymerization and Fabrication 3.3 Properties 3.4 Chemical Stability 3.5 Processing 3.6 Applications 3.7 Developments in Polyphthalamide Based Blends

and Composites and their Applications References

Polyetherimide Sabrina Carroccio, Concetto Puglisi, and Giorgio Montando 4.1 Introduction and History 4.2 Polymerization

4.2.1 Two Step Polymerization Reaction 4.2.2 One Step Processes 4.2.3 Synthesis Via Nucleophilic

Substitution Reaction 4.2.4 Synthesis Via Exchange Reactions

4.3 Properties 4.3.1 Thermal Properties 4.3.2 Electrical Properties 4.3.3 Mechanical Properties

4.4 Stability 4.4.1 Hydrolitic Stability 4.4.2 Thermal Stability 4.4.3 Thermo and Photo Oxidative Stability

4.5 Special Additives 4.6 Processing 4.7 Applications 4.8 Environmental Impact and Recycling 4.9 Recent Developments In Polyetherimides

Based Blends and Composities References

43

43 47 53 61 66 68

71 75

79

79 82 82 82

85 87 88 89 89 92 92 92 95 96 99 99

101 102

102 105

Poly(ether-foZocfc-amide) Copolymers Synthesis, Properties and Applications 111 Annarosa Gugltuzza 5.1 Introduction 111

2.

2.

2.

CONTENTS

5.2 Synthesis and Micro-phase Separated Morphology 113

5.3 Nomenclature, Properties and Relevant Area Applications 117

5.4 Compounding and Special Additives 122 5.5 Environmental Impact and Recycling 123 5.6 Poly ether-block-amides Membrane in

Separation Processes 124 5.6.1 Treatment of Gaseous Streams 126 5.6.2 Water Permeable Poly(ether-block-amide)

Membranes 130 5.6.3 Separation of Organic Compounds

from Organic and Aqueous Streams 131 5.7 Poly(ether-block-amide) Membranes in Food 133 5.8 Concluding Remarks 135 References 136

Aromatic Polyamides (Aramids) 141 José M. Garcia, Felix C. Garcia, Felipe Serna, and José L.dela Pena 6.1 Introduction and History 142 6.2 Polymerization and Fabrication 145

6.2.1 Polymerization 145 6.2.2 Fabrication 149

6.3 Properties 149 6.4 Chemical Stability 154 6.5 Special Additives 154 6.6 Processing 157

6.6.1 Processing PMPI and ODA/PPPT 157 6.6.2 Processing of PPPT 157

6.7 Applications 158 6.8 Environmental Impact and Recycling 161 6.9 Recent Developments in Aromatic

Polyamides and their Applications 162 6.9.1 Forthcoming and Future Application of Aramids 163 6.9.2 Polyamides with Improved Solubility 171 Acknowledgments 174 References 174

Polyaniline 183 Melek Kiristi and Ay segui Uygun 7.1 Introduction and History 183

2.

2.

vi CONTENTS

CONTENTS

7.2 Polymerization and Fabrication 184 7.3 Properties 186

7.3.1 Electrical Properties of Polyaniline 186 7.3.2 Chemical Properties of Polyaniline 186 7.3.3 Mechanical Properties of Polyaniline 187 7.3.4 Optical Properties of Polyanilines 188

7.4 Chemical Stability 188 7.5 Compounding and Special Additives 189 7.6 Processing 195 7.7 Applications 197 7.8 Environmental Impact and Recycling 202 7.9 Recent Developments in Polyaniline Based

Blends and Composites and their Applications 203 References 205

Polyimides: Synthesis Properties, Characterization and Applications 211 Abdolreza Hajipour, Fatemeh Rafiee, Ghobad Azizi 8.1 Introduction 211 8.2 Synthesis and Properties of Polyimides 213

8.2.1 Two-step Poly(amic acid) Process 213 8.2.2 Bulky Substituent in Polymer

Backbone 215 8.2.3 Polyimides with Flexible Ether Links 217 8.2.4 Polyimides Containing

Trifluoromethyl Group 221 8.2.5 Polyimides Containing Pyridine 228 8.2.6 Polyimides Containing Silicon 233 8.2.7 Polyimides Containing Phosphine

Oxide Group 233 8.2.8 Synthesis of Polyimides via

Dithioanhydride and Diamine 235 8.2.9 Synthesis of Polyimides via Polyamic

Acid Alkyl Esters 236 8.2.10 Synthesis of Polyimides via Polyamic

Acid Trimethylsilyl Esters 238 8.2.11 Polyimides Containing Six

Membered Rings 239 8.2.12 Synthesis of Polyimides via

Dianhydride and Diisocyanate 241

2.

vi CONTENTS

CONTENTS ix

8.2.13 Preparation of Polyimides via Imide Exchange 243

8.2.14 Synthesis of Polyimides via Mitsunobu Reaction 244

8.2.15 Synthesis of Polyimides via Coupling by using Metals 245

8.2.16 Green Media for Preparation of Polyimides 246

8.2.17 Copolymers of Polyimides 251 8.3 Characterization and Analysis of Polyimides 258 8.4 Applications 261

8.4.1 Polyimides for Electronic Applications 262 8.4.2 Application of Polyimides in Membranes 270 8.4.3 Application of Polyimides in Fuel Cells 273 8.4.4 Polyimide Foams 275 8.4.5 Adhesives 276

References 277 Index 289

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List of Contributors

Zulkifli Ahmad graduated with his doctoral degree from University of Reading, UK in 2005. His main research interest is the synthesis of high performance polymers with application in opto-electronic devices. He has published 50 papers in refereed journals and pre-sented talks in several international conferences as well as authored a monograph on crystal structure of high performance polymers. At present he is at Universiti Sains Malaysia as an Associate Professor.

Carlos Alemän earned his PhD in Sciences at the Technical University of Catalonia in 1994 and is currently a full professor there. He has received several awards including the Distinction of the Generalität de Catalunya to the University Research (2003), the В Research Award of MICINN (2006), and the ICREA-AC ADEMIA from ICREA Foundation (2007). He is group leader of the "Innovation in Materials and Molecular Engineering" (Chemical Engineering Department) and "Nanochemistry/Conducting" (CRNE) laboratories.

Sabrina Carroccio is a researcher at the Institute of Chemistry and Technology of Polymers of the National Research Council (CNR), Catania, Italy. Her research interests on degradation of polymers include molecular characterization of macromolecules by advances mass spectrometry techniques, polymer pyrolysis, polymer thermo and photo oxidation mechanisms.

EC. Garcia is a professor in the Department of Chemistry at the University of Burgos, Spain. He received his PhD at the University of Burgos, Spain in 2001. His research interest is in polymers with sensing capabilities in water environments.

J.M. Garcia is a professor in the Department of Chemistry at the University of Burgos, Spain. He received his PhD in Chemistry at the Complutense University of Madrid, Spain, in 1995. Prof. Garcia is a co-author of more than 50 peer reviewed scientific publications, books and book chapters, and has a number of patents. His prin-cipal areas of research are high performance materials, functional polymers, and sensory polymers as sensing materials for water environments.

XI

xii LIST OP CONTRIBUTORS

Ghobad Azizi Ghahfarrokhi received his MS degree in 2008 in organic chemistry from Isfahan University of Technology, Isfahan, Iran, He is pursuing his PhD degree in organic chemistry and his research interests are organic synthesis in ionic liquid media, MW assisted reactions and organometallic catalyzed reactions.

Annarosa Gugliuzza is a senior researcher at the Institute on Membrane Technology, ITM-CNR, Italy. She has a degree with honours in Chemistry and a PhD in Chemical Science. She is a membrane technologist with solid expertise in advanced materi-als and development of highly structured membranes with specific functions at molecular scale by sophisticated nanotechnologies, including self-assembly and layer-by-layer techniques.

Abdolreza Hajipour received his MS degree in 1983 from Shiraz University Iran and his PhD degree in organic chemistry from Wollongong University, Australia in 1994. He is a Professor of Organic Chemistry at Isfahan University of Technology. His research interests cover the synthesis of novel optically active poly-mers, microwave-assisted organic and polymerization reactions, solid-state reactions, new reagents for oxidation and reduction of organic compounds.

José I. Iribarren received his PhD in Sciences from the Technical University of Catalonia (Spain) in 1996. After many years devel-oping his research activity in the structural characterization of chiral polyamides, in 2003 he joined the "Innovation in Materials and Molecular Engineering" group at the Technical University of Catalonia. His current research interests concern the protection against corrosion using conducting polymers.

Melek Kiristi is a PhD candidate with research interests in the syn-thesis and application of conducting and biopolymers. She holds a BS degree from Suleyman Demirel University in Isparta, Turkey and a MS degree from Suleyman Demirel University in Isparta, Turkey.

Giorgio Montaudo is a Professor in the Department of Chemistry, University of Catania, Italy. He has been the Director of ICTMP-Catania of the CNR of Italy. Dr. Montaudo received a PhD in chem-istry from the University of Catania and has been active in the field of the synthesis, degradation, and characterization of polymeric

LIST OF CONTRIBUTORS xiii

materials by mass spectrometry. He is the author of more than 300 publications in international journals and chapters in books.

J.L. de la Pena is a Professor in the Department of Chemistry at the University of Burgos, Spain. He carried out his doctoral studies at the Institute of Polymer Science & Technology, Spanish National Research Council (CSIC), receiving his PhD in Chemistry at the Complutense University of Madrid, Spain, in 1972. His research interests cover all fields of polymer preparation and applications.

Concetto Puglisi is a Research Manager in the Institute of Chemistry and Technology of Polymers of the Italian National Research Council (CNR). He received his degree in Industrial Chemistry at the University of Catania in 1978. His research activity include ther-mal degradation and oxidation mechanisms of polymers, mecha-nisms of chemical exchange of polymer blends in the molten state and application of advanced mass spectrometry techniques to the analysis of polymers.

Jordi Puiggali earned his PhD in Industrial Engineering at the Technical University of Catalonia (UPC) in 1987 and is currently full professor at the same University. His research activity is mainly focused in the development of biodegradable polymers for bio-medical applications and in the structural studies of polyamides and polyesters. He is group leader of the "Synthetic Polymers: Structure and Properties" (http://psep.upc.edu), "Macromolecular Chemistry" and "Nanochemistry" (http://www.upc.edu/crne) laboratories of the Chemical Engineering Department of the UPC.

Fatemeh Rafiee received her MS degree in 2007 in organic chem-istry from Isfahan University of Technology, Iran, She is pursuing her PhD degree in organic chemistry at the Isfahan University of Technology, Iran. Her research interests are organic synthesis in ionic liquid media, MW assisted reactions and organometallic cata-lyzed reactions.

F. Serna is Associate Professor in the Department of Chemistry at the University of Burgos, Spain. He carried out his doctoral studies at the Institute of Polymer Science & Technology, Spanish National Research Council (CSIC), receiving his PhD in Chemistry at the Complutense University of Madrid, Spain, in 1985. His research interest is related with polymers for advanced technologies.

xiv LIST OF CONTRIBUTORS

Aysegul Uygun is a Professor of Chemistry at the Department of Chemistry in the Middle East Technical University, Turkey with expertise in polymer chemistry Her research interests include conducting polymers. Prof.Uygun has more than 50 publications in scientific journals. She received her PhD degree from Suleyman Demirel University in Isparta, Turkey She is the recipient of DFG and Fulbright Scholarships.

1

Engineering and Specialty Thermoplastics: Nylons

State of Art, New Challenges and Opportunities Visakh. P. M1 and Sabu Thomas2

t2School of Chemical Sciences, Mahatma Gandhi University, Kerala, INDIA

2Centrefor Nanoscience and nanotechnology, Mahatma Gandhi University, Kerala, INDIA

Abstract This chapter discuses a brief account on various types of nitrogen containing engineering polymers. Synthesis, morphology, structure, properties and applications of all different types of nitrogen containing engineering polymers are summarized in a concise manner. The new chal-lenges and opportunities are also discussed.

1.1 Polyamide-imides

Polyamide-imides are thermoplastic amorphous polymers that have exceptional mechanical, thermal and chemical resistant properties. These properties put polyamide-imides at the top of the price and performance pyramid. Polyamide-imides are pro-duced by Solvay Advanced Polymers under the trademark Torlon. Other high-performance polymers in this same realm are poly-etheretherketones and polyimides. Polyamide-imides hold, as the name suggests, a positive synergy of properties from both poly-amides and polyimides, such as high strength, melt processibility, exceptional high heat capability, and broad chemical resistance.

Sabu Thomas and Visakh P.M. (eds.) Handbook of Engineering and Specialty Thermoplastics, (1-10) © Scrivener Publishing LLC

1

2 HANDBOOK OF ENGINEERING AND SPECIALTY THERMOPLASTICS

Polyamide-imide polymers can be processed into a wide variety of forms - from injection or compression molded parts and ingots - to coatings, films, fibers and adhesives. Generally these articles reach their maximum properties with a subsequent thermal cure process.

1.2 Polyetherimide (PEI)

Polyetherimide (PEI) is an amorphous, amber-to-transparent ther-moplastic with characteristics similar to the related plastic PEEK. Relative to PEEK, PEI is cheaper, but less temperature-resistant and lower in impact strength. Polyetherimide combines high tem-perature resistance, rigidity, impact strength, and creep resistance. Glass-fiber-reinforced PEI plastic grades are available for general-purpose molding and extrusion; carbon-fiber-reinforced and other specialty grades also are produced for high-strength applications and PEI itself can be made into a high-performance thermoplastic fiber. PEI has found use in medical applications because of its heat and radiation resistance, hydrolytic stability, and transparency; in the electronics field, it is used to make burn-in sockets, bobbins, and printed circuit substrates; automotive uses include lamp sock-ets and under-hood temperature sensors; and PEI plastic sheeting is used in aircraft interiors. The PEI's history started in 1970, when USSR researchers (1) introduced the concept that the insertion of a flexible linkage into the polyimide chains considerably decreased glass transition temperatures without significantly lowering of thermal stability. Due to the wide range of PEI's applications, sci-entists continuously report studies concerning PEI synthesis from new monomers (2-4).

1.3 Poly(ether-block-amide)

Polyether block amide or РЕВА is a thermoplastic elastomer (TPE). It is also known under the tradename of РЕВ AX® (Arkema). It is a block copolymer obtained by polycondensation of a carboxylic acid polyamide (PA6, PAH, PAI2) with an alcohol termination polyether (PTMG, PEG). РЕВА is a high performance thermoplastic elastomer. It is used to replace common elastomers - thermoplas-tic polyurethanes, polyester elastomers, and silicones - for these characteristics: lower density among TPE, superior mechanical

ENGINEERING AND SPECIALTY THERMOPLASTICS: NYLONS 3

and dynamic properties (flexibility, impact resistance, energy return, fatigue resistance) and keeping these properties at low tem-perature (lower than -40 °C), and good resistance against a wide range of chemicals. It is sensitive to UV degradation. Challenging high-performance polymeric materials are in high demand and poly(ether-block-amide) copolymers meet the requirements of advanced applications in various marketplaces. Thermoplastic elastomers with desired final properties can be tailored through addressed interplay of polymer segments having different chemical nature, length, and weight. Insightful investigations have suggested that the micro-phase separated morphology as the major factor for the outstanding properties of these copolymers that are not usu-ally observed for each individual component. Excellent mechanical resistance enhanced chemical inertia and powerful perm-selective transport properties can be regarded as the result of the intricate interplay of the various constituents of these segmented copoly-mers. Excellent chemical, mechanical and transport properties of these polymers render them challenging systems for a broad range of applications, including high-performance waterproof breathable clothing, barrier films, engineered packaging, membrane separa-tion processes. It is important to add that these materials are being used for many advanced industrial applications, including textile, packaging and medical devices. The latter appears to be a key issue to meet the requirements of advanced applications in textile, con-struction, food and waste processing, packaging and medical fields.

1.4 Aromatic Polyamides

Poly(amide)s, most commonly called polyamides, are poly-mers incorporating the amide group in their repeating unit (-CO-NH-) (5). Aromatic polyamides, wholly aromatic polyam-ides, or aramids, are considered to be high-performance materi-als owing to their outstanding thermal and mechanical resistance. The high performance properties of these materials can be attrib-uted to their fully aromatic structure and amide linkages, which give rise to stiff rod-like macromolecular chains that interact with each other via strong and highly directional hydrogen bonds. These physical links deeply favor the development of effec-tive crystalline micro-regions or domains, resulting in a compact intermolecular packing and cohesive energy. The better-known

4 HANDBOOK OF ENGINEERING AND SPECIALTY THERMOPLASTICS

commercial aramids, poly(p-phenylene terephthalamide) and poly (m-phenylene isophthalamide) are used in advanced technolo-gies in every industrial field, and have been transformed into high-strength and flame resistant fibers and coatings with broad applications in advanced industrial products, such as heat and cut protective clothing, ballistic-protection products, sport fabrics, spe-cialty paper products, transmission belts, friction products, indus-trial filters and membranes, and special pipes, among others. Owing to the above mentioned chemical and physical characteristics, they exhibit extremely high transition temperatures, which lie above their decomposition temperatures. They are sparingly soluble in common organic solvents and, accordingly, can only be transformed upon solution from polar aprotic solvents or strong inorganic acids. Hence, the expansion of the applications of aramids involves, from one side, increasing their solubility, thereby improving their trans-formability, and, from other side, incorporating new chemical func-tionalities in the polyamide backbone or lateral structure in order to provide key characteristics for their application in cutting edge technological fields. These fields are related with new electrochro-mic, luminescent or optically active materials, gas separation and ion exchange membranes, macromolecules with sensing and supra-molecular capabilities, biomaterials for medical applications, mate-rials with even higher mechanical and thermal resistance, etc. The first all-para oriented aramid, poly(p-benzamide) (PPBA), was mar-keted by Du Pont under the 'Fiber B' trade name. Production only lasted a few years, probably due to economic reasons. (6,7)

Poly(p-phenylene terephthalamide) (PPTA)-based fabrics offer four times the protection of cotton fabrics and eight times the pro-tection of leather based clothes, offering heat protection as well. The PPTA fibers are extremely cut-resistant, which makes them ideal for use in: cut-resistant gloves, leg protection (e.g., for for-estry workers), anti-vandalism fabrics (e.g., for bus and train seats), etc. The excellent energy absorption properties, tenac-ity and impact resistance makes PPTA valid for helmets and soft (bullet-resistant vests) and hard (armored police and civilian vehi-cles) ballistics. The superior performance-to-weight ratio of ara-mids makes them useful for reinforcing high-performance tires, conferring the stability to the tires, durability and reduced fuel consumption. The aramids are used in passenger car tires, motor-cycle tires, bicycle tires, truck and bus tires, agricultural tires, off-road tires, airplane tires and solid tires.

ENGINEERING AND SPECIALTY THERMOPLASTICS: NYLONS 5

Aramids encounter applications in the manufacture of hoses when hose specifications for bursting pressure, longevity, tempera-ture and chemical resistance are extremely high. Transmission belts reinforced with aramids are used for applications demanding low creep, high dimensional stability, fatigue resistance, temperature resistance, precise synchronization and low operating noise belts, i.e., in the automotive industry.

The thixotropic aramide-reinforced resins provide viscosity con-trol for applications in a full range of temperatures, from cryogenic to 350 °C, and media, providing inertness in most common chemi-cals, including organic solvents. Moreover, the high strength, light weight and thermal stability of paper made with these polymers allows manufacturers of aerospace and marine equipment to pro-duce safe components that perform better and last longer than their alloy equivalents. Aramids are used to reinforce ropes and cables wherever safety and protection are essential, showing significant advantages over other synthetic yarns and steels in ropes and cables. Aramids are used in a wide range of composite applications in the industrial, leisure, civil engineering, ground transportation and aerospace markets, with new applications added daily, i.e., sails and reinforced hulls of sailing boats in the marine industry, rotor blades and structural parts in aerospace industry, wind tur-bines in new energy fields, high-pressure vessels and circuit break-ers in industrial components, lightweight parts for heavy-duty purposes in ground transportation, etc.

1.5 Polyaniline

Polyaniline (PANI) is a conducting polymer of the semi-flexible rod polymer family. Although the compound itself was discov-ered over 150 years ago, only since the early 1980s has polyaniline captured the intense attention of the scientific community. This is due to the rediscovery of its high electrical conductivity. Amongst the family of conducting polymers and organic semiconductors, polyaniline is unique due to its ease of synthesis, environmental stability, and simple doping/dedoping chemistry. Although the synthetic methods to produce polyaniline are quite simple, its mechanism of polymerization and the exact nature of its oxidation chemistry are quite complex. Because of its rich chemistry, poly-aniline is one of the most studied conducting polymers of the past

6 HANDBOOK OF ENGINEERING AND SPECIALTY THERMOPLASTICS

50 years. Poh/aniline (PANI) is a unique polymer among a family of conducting polymers and has semiconductor properties. It was first called as "aniline black" in organic form as part of melanin, like organic polymer in 1934. Melanin is a natural material pro-tecting the skin by regulating UV exposure through a polyaniline interaction. In the end of 1990, PANI became evident that it was highly useful polymer and could be used in applications varying from smart windows to electronic chips. PANI can be configured to conduct across a wide range, from insulation to conductive pur-poses. It is flexible appealing for manufacturing use and has granu-lar form which can be mixed with an organic chemical and painted or sprayed onto a substance to form a smooth surface of polyani-line. From economic point of view, the PANI is significantly supe-rior to other conducting polymers because the aniline monomer is less expensive than other monomers. The synthesis of PANI is simple and has many application fields. PANI has many potential applications in multidisciplinary fields because of its unique prop-erties. PANI can be applied in different areas such as electronics, thermoelectric, electrochemical, electro-luminescence, chemical, membrane, coatings, sensors, and so on.

1.6 Polyimides

Polyimide (sometimes abbreviated PI) is a polymer of imide mono-mers. Polyimides have been in mass production since 1955. Typical monomers include pyromellitic dianhydride and 4,4'-oxydianiline. Polyimides (PI) are a class of thermally stable polymers that are often based on stiff aromatic backbones. Polyimides were first pre-pared by Bogert and Renshaw in 1908, and they were then widely used and rapidly developed in the early 1960s (8). Polyimides have received great attention as they are very useful for many high-tech applications (9). The use of polyimides as high-performance and high-temperature thermoplastic materials in various applications stems from the attractive combination of chemical, mechanical and physical properties. Polyimides have found wide usage as films, coatings, adhesives, and matrix resins due to their excellent elec-trical and mechanical properties, high thermal and chemical sta-bility, good solvent resistance, and dimensional stability. They are generally used as flexible circuitry substrates, interlayer dielectrics and passivation and protective coatings in high density electronic

ENGINEERING AND SPECIALTY THERMOPLASTICS: NYLONS 7

packaging devices. The chemistry of polyimides is in itself a vast area with a large variety of monomers available and several meth-odologies available for synthesis. The most widely practiced pro-cedure in polyimide synthesis is the two-step poly(amic acid) (PAA) process. It involves reacting a dianhydride and a diamine at ambient conditions in a dipolar aprotic solvent to yield the cor-responding poly(amic acid), which is then cyclodehydrated to the polyimide either thermally or chemically The thermal imidization of the poly(amic acids) is especially useful when the final product is desired in a film or a coating form and chemical imidization is a useful technique for manufacturing molding powders.

Most polyimides are infusible and insoluble due to their planar aromatic and hetero-aromatic structures and thus usually need to be processed from the solvent route. One step method- high tem-perature solution polymerization is employed for polyimides that are soluble in organic solvents at polymerization temperatures. The process involves heating a stoichiometric mixture of monomers in a high boiling solvent or a mixture of solvents at high tempera-ture. The imidization proceeds rapidly at these temperatures and water generated due to the reaction is distilled off continuously as an azeotrope along with the solvent. The properties of polyimides can be dramatically altered by minor variations in the structure. The subtle variations in the structures of the monomer components have a tremendous effect on the properties of the final polyimide. The infusibility and limited solubility of unsubstiruted polyimides are characteristic properties which restrict synthesis, characteriza-tion, processing, and applications, particularly for a high molecular weight material. Thus, a variety of concepts for structural modifi-cations such as bulky pendant groups, flexible alkyl side chains, alicyclic monomers, incorporation of pendent trifluoromethyl or tri-fluoromethoxy groups, noncoplanar biphenylene moieties, as well as flexible alkyl or aryl ether spacers have been used for the reduc-tion of several types of polymer chain-chain interactions, chain packing and charge transfer electronic polarization interactions and thus to enhance the solubility and lower the phase transition temperatures. Another method is via copolymerization to synthe-size copolymers to improve the processability. These copolymers can be synthesized from various aromatic monomers containing anhydride, carboxylic acid, and aromatic diamine by condensation. Polyimides may also be conveniently prepared by the reaction of a diisocyanate and a dianhydride. Other methods for synthesis of

8 HANDBOOK OF ENGINEERING AND SPECIALTY THERMOPLASTICS

polyimides are imide exchange, mitsunobu reaction, coupling by using organometals and etc.

Because of the outstanding excellent electrical and mechani-cal properties, high thermal and chemical stability, good solvent resistance, low dielectric constants and dimensional stability, poly-imides are already used for many important industrial applications under extreme temperature conditions such as films, fibers, foams, membranes, binders, varnishes, plastics, matrix resins in high-temperature composites, glues, adhesives and injection molding products. Also aromatic polyimides have long been recognized as attractive for applications in the electronic industries, wire and cable insulation, electrical component seal assemblies and com-ponents for nuclear power plants, military aircraft and the space shuttle, flexible circuits, semiconductor pads, microprocessor chip carriers, coil insulation, magnetic wire insulation and solar arrays. Shundrina et al (11) prepared new highly fluorinated aromatic poly-imides based on hexafluoro-2,4-toluenediamine and commercially available dianhydrides (6FDA and ODPA) were synthesized by one-pot high temperature polycondensation in benzoic acid melt.

1.7 New Challenges and Opportunities

The main difficulty in the preparation of polyetherimide is due to control of the stoichiometric ratio of the reactants during the melt polymerization technique process. The relatively high tempera-tures used in the melt polymerization reaction joint to the different volatilities of monomers (anhydrides, amines and chain termina-tion agent) make the control of mixture stoichiometry very com-plicated. The ability of these polymers to embed different type and amount of organic and inorganic modifying agent opens new hori-zons towards the design of developed block copolymers with chal-lenging desired features that can satisfy the increasingly needs of the market. Challenging performance in poly ether-block-amides polymers is achievable through molecular design of new monomers or blending of different polymers and/or creation of copolymers. There is lot of interest to make high performance nanocomposites using these polymers by mixing with nanofillers. Research is also progressing to prepare these polymers form bio based materials.

ENGINEERING AND SPECIALTY THERMOPLASTICS: NYLONS 9

References 1. N. A Androva, M.I Bessenov, LA Laius, A.R Rudakov, Polyimides, Thecnomic,

Stamford, СТ Progress in Material Science Series, Vol. 7, Pag. 216,1970 2. B.K. Chen, Y. T. Fang, J.R Cheng, Macromol. Symp., Vol. 242, Pag.34,2006, 3. S. Kumar Sen, S. Maji, B.Dasgupta, S. Chatterjee, S. Banerjee, /. of Applied

Polymer Science,Vol.113, Pag.1550,2009. 4. Flaim T.D, Y. Wang, R. Mercado, Optical system design, Vol. 5250, Pag.2342003. 5. J.M. Garcia, F.C. Garcia, E Sema, J. L. de la Pena, High-performance aromatic

polyamides, Prog. Polym. Sci., Vol.35, Pag.623-686,2010. 6. R.J. Gaymans, "Polyamides", in M.E. Rogers, Т.Е. Long, eds., Synthetic

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2

Polyamide Imide Zulkifli Ahmad

School of Material and Mineral Resources Engineering, USM, Malaysia

Abstract Polyamide imide is a high performance polymer possessing excellent thermal, chemical and mechanical properties. It finds a wide application in extreme environment such as separatory membrane material, coating as well as structural parts. However, it is this very nature which limits its processability. Several structural modifications have been performed so as to affect its flowability, improve solvent solubility and thermal tractability. This includes main chain copolymerization, grafting, blending and forma-tion of nanocomposites. Synthesis of polyamide imide can be performed utilizing acid anhydride, acyl chloride and isocynate as initial monomers with diamine through substitution-condensation reaction. By choosing appropriate starting materials, final products can be tailor-made as to the required properties.

Keywords: Polyamide imide, high performance polymer, polymerization, optoelectronic, coating, blending, composites

2.1 Introduction and History

Polyamide imide (PAI) is a high performance polymer having extreme thermal and chemical properties. Essentially the recurring structure of a polyamide imide consist of

о

Sabu Thomas and Visakh P.M. (eds.) Handbook of Engineering and Specialty Thermoplastics, (11^2) © Scrivener Publishing LLC

11

12 HANDBOOK OF ENGINEERING AND SPECIALTY THERMOPLASTICS

A commercial polyamide imide Torion 4000T from Solvay Advanced Polymer is shown as below:

jail·-A r - H N - C ^ ^ Vi

ii A

Y Amide-imide

Imide-

0

6

imide

С L ) C-NH-Ar-HN-Cr il Д

Y Amide-amide

0

II 0

Their glass transition is beyond 250°C and most often do not display any melting temperature. They are also chemically stable and mostly insoluble in most organic solvents. These properties owed very much to the aromatic groups which make up the poly-mer backbone. However, it is these very properties which limit its widespread application due to the intractability in processing and solubility. With the presence of both imide and amide groups in the polymer repeating units, PAI possesses properties between poly-imides and polyamides which offer a good compromise between high thermal properties and processibility. In fact, polyimide are mostly processed using its polyamic precursor which has a lower thermal property and is soluble in most solvents. Several modifi-cations were accomplished in order to overcome these difficulties such as incorporation of flexible linkages like ester and amide func-tionality. Blending with other polymers is an option to improve the desired properties of PAL Composites are often formed with the addition of various additives and inorganic fibres as fillers.

As early as 1966, PAI was synthesized by reacting aryl polyiso-cyanate with trimellitic anhydride for the purpose of fabricating foam structure. [1] Following this, several mixtures of diacid were formulated with diisocyanate which gives polymeric products of different melt processability, viscosity, solvent solubility, molecular weight and fusibility. The utilization of acyl halide derivative of tri-mellitic anhydride with aromatic primary diamine occurred during late 60's. They were popularly used initially as wire coating materi-als such as magnet wire coating. Nowadays, due to their thermal and mechanical versatility, PAI are widely used in aerospace pro-grams, automobile and electrical industries, insulations, coatings, solvent resistant membranes application and electronic devices.

POLYAMIDE IMIDE 13

2.2 Polymerization

Polymerisation of PAI can be performed via several routes:

A. Acid Anhydride B. Acid Chloride C. Isocyanate

A. Acid Anhydride General methodology is to produce imide linkage with terminal primary amine group followed by condensation to amide linkages by carboxylic group at the acyl carbon. The imide linkage can be brought about by addition reaction of a dianiline with a difunc-tional carboxylic group. The most useful of the latter is trimellitic acid anhydride(TMAA):

о Trimellitic acid anhydride

Since the successful Yamazaki-Higashi phosphorylation reaction [2], the direct synthesis of high-molecular-weight PAIs was made from the TMA-derived imide ring-bearing dicarboxylic acids and aro-matic diamines utilising triphenyl phosphite (TPP) and pyridine as condensing agents [3,4] The formation of imide linkage occurs as depicted in the following reaction Scheme 2.1:

The first step involves nucleophilic addition-elimination of amine onto the carbonyl carbon of the anhydride. This step is performed at temperature 5-30 °C in polar aprotic solvent eg. NMP under nitrogen atmosphere. The resulted poly(amide amie acid) is sub-sequently imidized to affect ring closure with the released of water molecules. [5] The ring closure of polyamic acid is called imidiza-tion reaction. Several methods can be used for imidization[6]:

1. Distillation under reduced pressure for removing the solvent at decreasing temperature.

2. Adding dehydrating agent eg acetic anhydride to PAA solution with addition of catalyst eg pyridine or triethylamine.

3. Simultaneous removal of solvent and heat imidization by reduced pressure and heat treatment. This method

α tu о о о ч И

N —R —NHP

Scheme 2.1 General reaction scheme for the formation of polyamide imide.

s

о 4 w n

s ri

о ч с > и п СП

16 H

AN

DB

OO

K O

F EN

GIN

EE

RIN

G A

ND

SPECIA

LTY T

HE

RM

OPL

AST

ICS