Textile Fibres and Fibre Science
Textile Fibres and Fibre Science examines how fibre chemistry, morphology and molecular arrangement control processability and performance. The exam tests classification, moisture relations, tensile and elastic behaviour, thermal transitions and identification, usually with numerical unit conversions.
Core concepts
- Natural fibres include cotton, wool, silk and flax; man-made fibres include regenerated cellulose and synthetic polymers. Each has characteristic length, fineness, crimp and moisture behaviour.
- Crystallinity and orientation raise tenacity and modulus but usually reduce extensibility and dye accessibility.
- Moisture regain is equilibrium moisture expressed on oven-dry mass; moisture content uses total wet mass as the base.
- Tenacity is force per linear density, commonly cN/tex; extension is strain at break. Elastic recovery separates reversible from permanent deformation.
- Identification uses microscopy, solubility, burning and instrumental methods; no single test is conclusive for blends.
Worked example
A conditioned cotton sample weighs 108.5 g. After oven drying at 105°C it weighs 100.0 g. Moisture regain = (108.5 − 100.0) / 100.0 × 100 = 8.5%. Moisture content = 8.5 / 108.5 × 100 = 7.83%. The dry mass is the denominator for regain; the wet mass is the denominator for content.
Traps
- Reporting regain as content, or using the wet mass as the regain base.
- Mixing tex (g/1000 m) with denier (g/9000 m) and quoting tenacity without units.
- Treating a conditioned mass as oven-dry, especially for hygroscopic fibres.
- Assuming a blend's property is the simple average; interface and blend ratio matter.