Topic 1 of 6 · Form 5
Fibre science
Textile fibres are long-chain polymers. Properties depend on chain length, orientation and crystallinity: highly oriented, crystalline fibres are strong but less absorbent and less elastic.
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Polymer structure
Textile fibres are long-chain polymers. Properties depend on chain length, orientation and crystallinity: highly oriented, crystalline fibres are strong but less absorbent and less elastic.
Natural fibres
- Cellulose: cotton (convoluted ribbon-like fibre; hydrophilic; strong when wet; Zimbabwe grows cotton in Gokwe, the Zambezi Valley and other drier regions), linen, sisal and other bast fibres.
- Protein: wool (scales cause felting; crimp gives warmth and elasticity), silk (smooth triangular cross-section gives lustre), mohair.
Manufactured fibres
- Regenerated: viscose, lyocell (from wood pulp), acetate.
- Synthetic: polyester, nylon (polyamide), acrylic, elastane – made by melt, wet or dry spinning; thermoplastic, so they can be heat-set but melt.
- Microfibres and technical fibres (aramids for protective clothing).
Properties and testing
Strength, elongation, elasticity, absorbency (moisture regain), thermal properties, flammability, abrasion resistance, and pilling. Identification: microscopy, burning test, solubility tests.
Blends
Combine complementary properties (polycotton, wool–nylon socks).
Check yourself
- Why does wool felt when washed in hot water with agitation?
- Why can polyester be permanently pleated?
- What is moisture regain?
Show answers
- Its surface scales interlock and the fibres migrate and tangle, shrinking the fabric.
- It is thermoplastic – heat setting fixes the pleats.
- The percentage of moisture a dry fibre absorbs from the air under standard conditions.
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