Structure and Properties of High-Performance Fibers

Gajanan Bhat

• Publisher: Woodhead Publishing
• Year: 2016
• Print ISBN: 9780081005507
• eBook ISBN: 9780081005514
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

Structure and Properties of High-Performance Fibers explores the relationship between the structure and properties of a wide range of high-performance fibers. Part I covers high-performance inorganic fibers, including glasses and ceramics, plus carbon fibers of various types. In Part II, high-performance synthetic polymer fibers are discussed, while Part III reviews those natural fibers that can be used to create advanced textiles. The high-performance properties of these fibers are related to their chemistry and morphology, as well as the ways in which they are synthesized and spun.High-performance fibers form the basis of textile materials with applications in protection, medicine, and composite reinforcement. Fibers are selected for these technical applications due to their advanced physical, mechanical, and chemical properties.- Offers up-to-date coverage of new and advanced materials for the fiber and textile industries- Reviews structure-property relationships of high-performance inorganic, carbon, synthetic polymer, and natural fibers- Includes contributions from an international team of authors edited by an expert in the field- Reviews those natural fibers that can be used to create advanced textiles

1

Introduction to high-performance fibers

G. Bhat     The University of Georgia, Athens, Georgia, United States

Abstract

There is continuing interest in technical textiles around the world, and this is one of the fastest growing sectors of the manufacturing industry. Many of these products use specialty fibers and the search for new and improved fibers is continuing. The field of high performance fibers is continuously evolving, thanks to the efforts of many scientists and engineers in universities, research centers and industries. This book is an effort to capture the developments in the past several years on high performance fibers. This book has 14 chapters covering a wide range of fibers from inorganic to synthetic aliphatic, aromatic and cyclic polymeric fibers, and natural fibers that have been written by internationally recognized experts in their respective fields.

Keywords

Carbon nanotube-based fibers; Electrospun nanofibers; High-performance fibers; Melt-spun fibers; Nylon fibers; Silk; Wool

 

There is continuing interest in technical textiles around the world, and this is one of the fastest growing sectors of the manufacturing industry. Many of these products use specialty fibers and the search for new and improved fibers is continuing. As a result, we need to look at the developments in high-performance fibers from time to time. It is only once in a while that new revolutionary fibers are introduced and most of the time there are incremental changes in properties and performance of specialty fibers. The field of high-performance fibers is continuously evolving, thanks to the efforts of many scientists and engineers in universities, research centers, and industries. These continuous developments allow the fabrication of products with specific property and performance requirements. In majority of the cases it is the performance requirements that drive the innovation and development, although at times discoveries in arenas other than fibers and textiles are adapted to development of high-performance fibers. While traditionally most of the developments were done by fiber-related researchers, recently more and more inventions are coming from nontraditional investigators. Such discoveries have certainly benefited the fiber industry. This book is an effort to capture the developments in the past several years on high-performance fibers.

Although most of the fibers could be used in high-performance applications in some context, there are several fibers that are exclusively developed with unique structure and properties, making them unsuitable for apparels or other typical consumer applications. At the same time, some of the common textile grade fibers have been modified to achieve additional functionality over what is expected in everyday apparel fabrics. One has to remember that the expectations of the apparels have been changing and by the combination of different materials and processing techniques, several high-performance and intelligent fabrics have been introduced lately. In fact, this trend of developing functional and intelligent textiles is rapidly growing with interest from a wide range of industries.

The perception of high performance with respect to fibers has also been changing, and it is not possible to clearly distinguish what fibers are suitable for this category. In the early developments, fibers that met the requirements in industrial applications other than apparel or home textiles, which had either higher strength/modulus or thermal stability or chemical or flame resistance, were considered high-performance fibers. Recently, there are also several smart or intelligent fibers that have been gaining a lot of attention. These smart fibers, although many have mechanical properties comparable to that of typical textile fibers, could have the ability to respond to environmental conditions such as thermal, electrical, magnetic, or mechanical, or to other sources. In fact, there is increasing effort to incorporate them into textiles and recently a huge consortium has been funded from the US Department of Defense in partnership with several industries, states, and universities to bring revolutionary, smart, functional fibers from research laboratories to the manufacturing level and further incorporate them into fabrics. Of course, this exercise will possibly lead to a revolution in the high-performance fibers area as well. Whereas smart technology is likely to be important in future fabrics, such fibers are not included here as they are beyond the scope of this book.

The book has 14 chapters covering a wide range of fibers from inorganic to synthetic aliphatic, aromatic, cyclic polymeric, and natural fibers. The chapters two to four cover various carbon- and carbon nanotube (CNT)-based fibers. The second chapter reviews the important polyacrylonite (PAN)-based carbon fibers that are the most important and fastest growing categories in high-performance fibers. In addition to the overall review of the process of converting PAN precursor into carbon fibers, structure and property development during carbon fiber formation is thoroughly discussed. With increasing demand for low-cost carbon fibers, reducing the cost of precursors as well as the conversion cost is important so that an increase in the application of carbon fibers in automotives becomes a reality. The third chapter, which is on pitch-based carbon fibers, has a thorough discussion of different pitches, extrusion of pitch into fibers, and conversion of pitch into carbon fibers. There is an in-depth coverage of development of structure and relationship of structure to properties in these carbon fibers. Ever since the discovery of CNTs there has been increasing interest in them because of their extremely high strength, modulus, and electrical properties. Synthesis, structure, and properties of CNTs as well as CNT-reinforced fibers are reviewed in the fourth chapter. This chapter also covers the latest development in CNT-reinforced polymeric as well as carbon fibers and CNT yarns. Although CNTs have superior properties, the challenges to realize the properties in yarns and composite fibers have not been overcome. There is continuing effort to improve the structure and properties of CNT-incorporated fibers and yarns.

There are eight different chapters covering various synthetic organic fibers, which include chapters on fibers from polyester, rigid-rod polymers, polyethylene and propylene, nylon, polyaramids, electrospun nanofibers, and polyimides. Chapter five on aromatic polyester fibers includes the historical development, chemical structure, processing, and fiber structure and properties. These melt-spun fibers were developed as an alternate to polyaramids, which are expensive. In addition to high strength and modulus, these liquid crystalline polyester fibers show excellent flex resistance, which is desirable in many applications. Chapter six on rigid rod polymer fibers encompasses their aromatic and cyclic structures and includes poly p-phenylene benzobisoxazole and poly p-phenylene polybenzobisthiazole. Detailed discussion of polymerization, processing, structure, and properties is provided. Also approaches to improve the UV stability and other properties are addressed.

Gel-spun polyethylene fibers have the highest specific strength of any continuous fibers and the historic development of these fibers is discussed in detail in the seventh chapter. The major focus of this chapter is on the structure of these highly ordered and oriented ultrahigh molecular weight polyethylene fibers that is responsible for their unique properties. It is shown that there may be room for further improvement in the properties of these fibers by process optimization. Chapter eight on polypropylene fibers discusses how the combination of higher molecular weight polymer with process conditions such as high-temperature drawing can lead to high-tenacity fibers. Although high-strength, high-modulus polypropylene fibers do not have high thermal stability or properties comparable to that of other high-performance fibers such as Kevlar or high-strength, high-modulus polyethylene fibers, these have properties that meet the requirements for many demanding applications, and the cost of these fibers will be a lot lower than that of other high-performance organic fibers.

Chapter nine on nylon fibers covers recent developments in spinning and postspinning treatments to produce high-performance fibers. These techniques influence the microstructure resulting in improved tensile, thermal, and chemical properties. Approaches that help to produce high-performance nylon fibers, by appropriately modifying the structure of these fibers by spinning process modification as well as postspinning operations, is elucidated. Chapter 10 on polyaramids addresses both Kevlar and Nomex-type fibers including their polymerization, fiber spinning, structure development during synthesis, and processing leading to superior properties. Recent advances in understanding their structure as well as surface modification to improve properties of composites are also of interest.

Electrospinning of nanofibers has been extensively studied and the recent developments are summarized in Chapter 11. In addition to the traditional needle electrospinning, other approaches such as needleless spinning are elaborated. Achieving various structures including controlled architecture of three-dimensional webs is discussed very well. Recent developments include forming nanofiber yarns and the ability to produce a wide range of patterns. The use of electrospun nanofibers in emerging applications such as batteries, super capacitors, solar cells, and piezoelectric devices is elaborated. Electrospinning can be used to produce nanofibers from a wide range of polymers that have a suitable solvent. High-performance polyimide fibers are discussed in Chapter 12, which covers different approaches to produce polyimide fibers and various types of polyimides. Special emphasis is given to polymer synthesis, fiber formation, imidization, and the microstructure of the fibers.

Chapters 13 and 14 are dedicated to two natural protein fibers, silk and wool. Both have been in use for a long time. Whereas silk fibers produced from silkworms have been used for thousands of years because of their unique luster, tactile properties, durability, and dyeability, lately there has been interest in high-strength, high-modulus silk fibers. Silk fibers obtained from various types of spiders have been evaluated and some of them have shown extremely high strength, modulus, elasticity, and toughness. The chemical composition and structural features that lead to improved mechanical properties as well as various types of silk worms and spiders available around the world are thoroughly discussed. Also all aspects of the sericulture industry are covered in detail. Wool, another natural fiber that has been used for many years, has unique properties and this fiber has been studied extensively to understand its structure so that synthetic fibers of comparable properties can be produced. Wool fibers have good thermal and acoustical insulation properties and have also been demonstrated to be efficient in filter media and some medical applications. Ballistic fibers such as Kevlar have shown improved performance when blended with wool fibers. Lately, wool fibers have been used in some composite applications as well. In addition, both silk and wool are sustainable fibers.

This book has been made possible because of the contributions from a team of internationally recognized experts in their respective fields. These authors have put in a great deal of time and effort to make this possible. I am thankful to all the contributing authors for making this happen. I also extend my thanks to Ms. Sarah Lynch, Ms. Christina Cameron, Ms. Charlotte Cockle, and Mr. Edward Payne from Elsevier for their support and patiently working with us throughout the process. This book has a wealth of useful information, and it is my sincere hope that readers from academia, industry, and research institutes working in the areas related to fibers as well as others interested in high-performance fibers will immensely benefit from reading this book.

Part One

High-performance inorganic fibers

Outline

2. High-performance PAN-based carbon fibers and their performance requirements

3. High-performance pitch-based carbon fibers

4. High-performance carbon nanofibers and nanotubes

2

High-performance PAN-based carbon fibers and their performance requirements

E. Frank¹, D. Ingildeev¹, and M.R. Buchmeiser^{1,2 1}Institute of Textile Chemistry and Chemical Fibers (ITCF Denkendorf), Denkendorf, Germany ²Institute of Polymer Chemistry, University of Stuttgart, Stuttgart, Germany

Abstract

The chemistry and physics of high-performance PAN-based carbon fibers are summarized. Performance requirements are addressed and put into context with structural features, which in turn are discussed with precursor issues. Special emphasis is put on precursor polymer synthesis, fiber spinning, oxidation, carbonization, and graphitization as well as on the surface treatment of carbon fibers. Complementary, structural issues are discussed within the context of carbon fiber properties, applications, and future trends.

Keywords

Carbon fibers; Carbonization; Graphitization; Modification; Oxidation; Polyacrylonitrile; Structure; Surface; Wet spinning

Carbon fibers (CFs) have high tensile strengths up to 7 GPa with very good creep resistance, low densities (1.75–1.95 g/cm³), and high moduli (20...

Table of contents

• Cover image
• Title page
• Table of Contents
• The Textile Institute and Woodhead Publishing
• Copyright
• List of contributors
• Woodhead Publishing Series in Textiles
• 1. Introduction to high-performance fibers
• Part One. High-performance inorganic fibers
• Part Two. High-performance synthetic polymer fibers
• Part Three. High-performance natural fibers
• Index