Both natural and man-made fibres are mainly composed of the compounds belonging to polymers or macromolecules. The macromolecular structure is necessary for the production of materials of high mechanical strength and high melting point. it is assumed that a polymer must minimum requirements if it is to serve as a fibre. These requirements are mentioned below:
The polymer must be a linear flexible macromolecule with a high degree of symmetry. The effective cross-sectional diameter should be less than 15 Angstrom. The polymer should not contain any bulky side groups or chains.
2. Molecular mass
The polymer must have a comparatively high molecular mass. The average length of its molecular chain should be in the order of 1000 or more.
Configuration is an arrangement of monomers in the polymer. The molecule must have the capacity to adopt an extended configuration and state of mutual alignment.
A polymer should have at least a high degree of intermolecular cohesive power. This indicates that the molecular chains should have a sufficient number of sites of attraction.
A high degree of orientation of the molecules in the polymer is a prerequisite for producing good tensile strength.