ABSTRACT
This chapter presents fibre structure and related properties. The structure of a fibre is described in terms of degree of polymerization, molecular orientation, molecular bonds, amorphous region crystallinity and crosslinks. Sophisticated techniques like electron microscope, X-ray and birefringence studies, etc. reveal the fibre structure. The properties of the fibre are not only dependent on the individual chains, but also on the way in which these chains are packed together in a fibre. The arrangement of the molecules in a natural fibre and the angle of inclination to the fibre axis is a characteristic of each natural fibre and for all practical purposes fixed and unalterable. Microfibrils consist of eleven protofibrils disposed in a certain order, so that in cross-section, nine of them form an external ring, while two of them are inside the ring. The polypeptide chains of silk may contain relatively few bulky side chains.
