Silk: Materials, Processes, and Applications

Narendra Reddy

• Publisher: Woodhead Publishing
• Year: 2019
• Print ISBN: 9780128184950
• eBook ISBN: 9780128196878
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

Silk: Materials, Processes, and Applications addresses the latest research on the structure and properties of silk fibers, properties of silk-based materials, and cutting edge-related industrial practices. It pays particular attention to mulberry silk, but unconventional silks such as spider silk and marine silk fibers are also covered. Although silk is one of the oldest known fibers, new research continues to shed light on its properties, leading it to be applied in new contexts particularly in the medical field, and new non-textile areas. In addition to structural and mechanical qualities, this book also includes a great deal of new research on the chemical modifications of silk fibers, and other processing methods. With a focus on practical methodologies, this is the most readable and readily applicable book on silk so far, making it a perfect guide for readers with a range of backgrounds. - Addresses the fundamental differences between mulberry, spider, and wild silks - Describes silk fiber and non-fiber forms, including hydrogels and films - In-depth coverage of silk-processing methods provides the perfect starting point for biotechnologists interested in the use of silk for non-textile applications

1

Sources and classification of silk

Abstract

Silk is an eternal fiber and unparalled in terms of luster, handle, comfort and many other unique properties. From being a primary source for apparel and other textiles, applications of silk has diversified into medical, cosmetic, biotechnology and other uses. Bombyx mori (B. mori) has been the predominant source of silk for centuries and continues to be the most common source for silk fibers. However, many other insects, plants and even marine organisms produce various forms of silk with distinct properties. It is not an overstatement to mention that silk is probably the only fiber that is produced on land, air and in water. In this chapter, an overview of the different sources for silk and their classification is provided. The rest of the chapters in the book mostly focus on B. mori silk and common wild silks but other forms of silk have also been discussed as and when appropriate.

Keywords

B. mori silk; Wild silks; Marine silks; Ant silks; Spider silks

1.1 Introduction

Unlike any other fiber, silk is produced on land, water and air. More than 23 different silk lineages in 17 insect orders have been recorded and classified (Table 1.1) (Sutherland et al., 2010). Most of the silk is produced by the Lepidoptera order of insects and specifically from the Bombycidae and Saturniidae species. Extensive studies have been done to further classify the silks produced by the different species. One example of classifying silk, based on the sequence of amino acids, is given in Fig. 1.1. In addition, silk can also be classified based on the gland in which it is produced. Similarly, silk species have been classified based on the differences in the FTIR spectra (Boulet-Audet et al., 2015) which also was able to distinguish silk based on their composition as seen from Fig. 1.2.

Table 1.1

Type of insects that produce silk, the life stage in which they produce the silk and the gland(s) from which the silk is generated.

Common name of insect	Life stage	Gland
Jumping bristletails, silverfish	Adult males	Type III secretory units
Mayflies	Larvae	Malpighian tubules
Dragon flies	Adult female	Unknown
Webspinners	All stages	Type III secretory units
Crickets	All stages	Labial glands
Book lice	Adult females	Labial glands
Thrips	Larvae and adults	Malpighian tubules
Kaboono montana Evans	Unknown	Unknown
Water beetles	Adult female	Colleterial glands
Plant eating beetles	Larvae	Malpighian tubules
Lacewings	Adult female	Colleterial glands
Lacewings and ant lions	Larvae	Malpighian tubules
Saw flies and parasitic wasps	Larvae	Labial glands
Parasitic wasps	Adult female	Abdomen secretion
Bees, ants and wasps	Larvae	Labial gland
Saw flies	Larvae	Labial gland
Wasps	Adult females	Type III secretory units
Wasps	Adult females	Labial glands
Fleas	Larvae	Labial glands
Dance flies	Adult males	Type III secretory units
Glowworms	Larvae	Labial glands
Midges	Larvae	Labial glands
Butterflies, moths, caddisflies	Larvae	Labial glands

Fig. 1.1 Phylogeny of lepidopteran insects based on the amino acid sequence of the gene 13 PCGs (Liu et al., 2013). Reproduced with permission through Elsevier Open Access Publication.

Fig. 1.2 Classification of silk producing Lepidopteran insects based on the differences in FTIR spe...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• 1: Sources and classification of silk
• 2: Structure and properties of silk fibers
• 3: New developments in degumming silk
• 4: Regenerated silk fibers
• 5: Electrospun silk fibers
• 6: Applications of silk
• 7: 3D printing silk
• 8: Future trends in the sources, processing and applications of silk
• Index