SPECIFIC FEATURES OF TEXTILE FIBRES

Textile fibres are units of matter characterized by flexibility, fineness and a high ratio of length to thickness. The fibers are several hundred times as long as it is wide.

Two of the main features are length and strength; the upper limit of length is immaterial for treads may be formed by simply twisting the long filaments. The lower limit is more important which should be minimum of 1 cm. Associated with the length of the fibrous, form is its fineness; the coarser textile, fibers are 700 times as long as they are wide, the finest is 5000, but good average is 1000 times. Coarse fibres such as jute are mostly used for low grade productions such as sacks, awnings etc.

Textile fibres must also possess sufficient strength not only to withstand the mechanical operation of spinning and weaving or knitting, and the various physical & chemical processes of bleaching, dyeing and finishing, but also to give satisfactory service in wear. Associated with tensile strength extensibility is also necessary; fibre of great strength is brittle will not give service in actual wear.

Elasticity is important not only in connection with recovery from creasing and distortion, but also with regard to the ability to withstand repeated stresses in actual service softness and suppleness are also important factors of the textile fibres. The two major attributes of textile fibres, therefore may be expressed as toughness and flexibility.

For commercial and economic reasons, good textile fibers must be abundant and cheap, and should be free from pests and disease such as moths and mildew (fungi).

The crimp of a fibre is important for the production of yarns by spinning. Fibres with a natural crimp have a softness which is lacking in the smooth fibres. The crimp is also important in holding air and offering thermal insulation. Crimp should be permanent and return after extension distortion, wetting, etc.

All fibres posses a characteristic cross-section; wool is circular and cotton ear-shaped. Long wools are the coarsest, but long cottons are the finest. The diameter of a fibre should not be great or a high degree of rigidity. The cross-section of manufactured fibres can be raised from flat ribbon-like structures of circular. The cross-section of a fibre also plays its parts in determining its spinning value; when cotton is mercerized, for example, the cross-section becomes round but the fibres are more difficult to spin.

The moisture relation or affinity for water vapor provides important textile properties; all the animal and vegetable fibres are hygroscopic and accommodate themselves to charges in atmospheric humidity. A fibre which cannot absorb moisture of little value for purposes of clothing, because surface condensation would wet the fibre and cause an unpleasant clammy sensation when in contact with the skin. The ability to absorb and desorb is also of great value in our clothing from the hygienic standpoint. The ability to wet into liquid water is desirable in textile materials, so that they may be bleached and dyed and easy for cleaning. 

A certain amount of luster is often required, but the luster should be more acceptable.

It is not to be expected that any one fibre would have all the desirable properties; indeed, such a textile material could not exist. But most popular textile materials posses a number of the valuable features discussed.

All textile fibres are composed of macromolecular produced by polymerization of simpler complex. The mechanism by which this is achieved in nature is obscure. Not every polymer can make a textile fibre. The difference lies in the spatial arrangement of the molecules. To make a successful fibre the macromolecules must be straight chain capable of lying parallel to each other in the direction of their longitudinal axis in such a way that they can exercise mutual attraction. The attraction forces are either chemical bonds, hydrogen bonds or van der Waals’ forces which are of a physical nature.

Cellulosic fibres contain of the order of 60-70% of molecules orientated in crystalline structure. It may also be of 100% crystalline. The regenerated celluloses of 38-40%, terylene 50%, nylon 50-60%. Textile fibres have high molecular weight. All textile fibres are high polymers, but all high polymers are not textile fibres.

Textile fibres are composed of numerous small units held together to make very large molecules i.e. macromolecules. Two kinds of forces are reasonable for holding various structural units together, namely primary and secondary forces. The primary forces hold the atoms together to form the molecular whereas the secondary forces, which are much weaker, hold the molecules together. These secondary forces are of great importance in holding the molecular chains of the fibres together.