Properties of Textile Protein Fibre

Protein Fibre Properties

Natural protein fibres are of animal origin. These are those fibres in which the fundamental chemical structure is composed of amino-acids joined in poly peptide chain. All protein fibres comprise the elements, carbon, hydrogen, oxygen, and nitrogen. Wool comprises sulphur as well. In each protein fibre these elements are combined in diverse arrangements. As a result properties of the various protein fibres may show some striking differences.

However, these share so many of common properties –

Strength

Except silk, tend to be weaker than cellulose fibres and they are weaker when wet than dry. Therefore they have to be handled attentively. During washing wool looses 40% of its strength.

Density and Specific Gravity

Their density and specific gravity tend to be lower than that of cellulose. Fabrics made from these strands are felt lighter in weight than comparable fabrics made from cellulose.

Resiliency

These strands have greater resiliency than cellulosic. They are more resistant to wrinkling and hold their shape.

Thermo Chemical Properties

These strands do not burn easily. When set a flame they may extinguish themselves. Burned strands smell like burning hair, flesh or feathers. They form a black crushable ash.

Heat Resistant Properties

These strands tend to be destroyed by dry heat. Wool becomes harsh, brittle and scorches readily with dry heat. It should be ironed as in the case of silk, with a press cloth or steam. White silk and wool turn yellow. They need lower ironing temperature than cotton and linen, with recommended temperatures around 500⁰F.

Hydroscopic Nature

These strands have excellent moisture absorbency and they absorb extra moisture at the saturation point. Therefore they are easy in wet damp climate though they tend to be warmer than cellulose fibres. Moisture prohibits brittleness in carpets.

Static Electricity

They are poor conductors and hence build up static charge, so the resulting yarns and fabrics tend to be release much static electricity, although this problem is subsided in presence of moisture.

Alkali

Natural protein strands have poor resistance to alkalis and can be dissolved in 5% solution of NaOH at low boiling point. When washing neutral or little alkaline soap or detergent should be utilized. Perspiration weakens the strands.

Bleaching

Chlorine bleaches destroy fibre and therefore should not be used. Fabrics can be bleached safety with hydrogen peroxide.

Sunlight

Sunlight discolors fabrics made from protein fibres, turning yellow after extended exposure. Although wool has better resistance to sunlight than cotton, it will degrade prolonged exposure to sunlight.