I am close to completing a book about Silk to be published by the SSRL. All going well it will be out early/mid 2021. The content is based around my Lecture series presented in Rivera, Uruguay in 2018. Here’s a small preview:
What is silk?
Silk is a natural proteinaceous secretion of
many kinds of invertebrates. It is usually secreted as a fibre, although may be
secreted as a glue or other substance. Some silk fibres are woven into textiles
by humans. The fibre is usually secreted as a liquid or gel and rapidly
self-assembles into a fibre. The vast majority of a silk fibre is composed
primarily of a protein called fibroin or, in the case of spider silk, spidroin
(which is a derivation of spider fibroins)2. It has,
despite being a fairly transparent fibre, a shiny appearance owing to its triangular
or prism-like shape. Silks have a density of around 1.3 g cm-3. While
this is lower than many other natural fibres (e.g. wool or cotton, at ~1.5 g
cm-3), it is greater than synthetic fibres (e.g. polyester, nylon,
at 1.1-1.2 g cm-3 g cm-3). Nevertheless, it is much less
dense than most of the high performing synthetics, like carbon fibre (at 2 g
cm-3). Despite its low density, silk (in particular silkworm moth
cocoon silk and spider dragline silk) has a greater
strength, elasticity, and toughness than most natural or synthetic materials (see Table 1). The significance of this I will explain later
when I discuss the uses of and properties of silk. Needless to say, silk has a
particularly low mass per unit volume for a high performing material. It is the
hierarchical structure of silk, from its sub-molecular order through to the bulk
fibre (for which I’ll give more details later), that enables such a high
performing material to be developed while maintaining a low density.
<TABLE 1: STRENGTH, ELASTICITY AND TOUGHNESS OF SOME NATURAL
AND SYNTHETIC FIBRES>
