Characteristics of synthetic fibre
Both natural and man-made fibres are mainly composed of the
compounds belonging to high polymers or macromolecules. Macromolecular
structure is necessary for production of materials of high mechanical strength
and high melting point. The natural fibres are found to consist chain molecules
of linear macromolecular type. Further, the chain molecules are oriented into
parallel bundles in the process of growth. Based on these investigations it is
assumed that a polymer must satisfy minimum requirements, if it is to serve as
a fibre. These requirements are mentioned below:
Flexibility
The polymer must be
a linear flexible macromolecule with a high degree of symmetry. The effective
cross sectional diameter should be less than 15 A. The polymer should not
contain any bulky side groups or chains.
Molecular
Mass
The polymer must have a comparatively high molecular mass. The
average length of its molecular chain should be in order of 1000 A or more
Configuration
The molecule must have the capacity to adopt an extended
configuration and state of mutual alignment.
Crystallinity
A polymer should
have at least a high degree of intermolecular cohesive power. This indicates
that the molecular chains should have sufficient number of sites of attraction.
Orientation
A high degree of orientation of the molecules in the polymer
is a pre- requisite for producing good tensile strength.
