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Physical properties
Strength Wool fibre among the other natural fibers is considered weak due to the amorphous structure of the fibre. However it is possible to produce durable fabrics by carefully choosing the method of spinning and the weave. Strength is not an important factors for woolen fabrics intended for providing warmth.
Elasticity Wool is an elastic fibre supported by its helix structure. It has natural 3 dimensional crimp which is helpful for its elastic recovery. Therefore, wool fibre has high elongation and also has very high elastic recovery.
Resiliency Wool has high resiliency as compared to all fibers and thus exhibits good crease resistance. The fabric wrinkles less than other fabrics and also recovers fast if wrinkled.
Flexibility As the crystallinity in fibre is less wool fibre has high flexibility which is an important factor in production of soft fabrics.
Abrasion resistance Wool fabrics show low to medium abrasion resistance in case of apparel fabrics. High abrasion resistance is found in carpet wool.
Resilience: Wool fibre exhibits very high resilience. When crushed, it springs back to shape showing its exemplary resilience. Many structural aspects of wool fibre contribute to its resilience therefore, wool fabrics are more wrinkle free and even if wrinkled, ageing overnight makes it free from wrinkles.
Moisture Regain: Wool fibres can absorb large quantities of water as the fibres possess amorphous structure. Wool can absorb 13-16% of moisture under standard conditions. It may absorb more than 29% of its weight under saturation conditions.
Due to its scaly nature wool fibre has natural water repellency. Water beads up on the surface of the wool fabric, thus making it suitable for light rainwear.
One important aspect of wool is sorptive character is that it keeps the wearer warm even though it absorbs lot of water due to its very high heat of melting.
Dimensional Stability: Wool fabrics show poor dimensional stability as the fibres interlock and shrink during processing, use and care of fabrics. Wool fabrics intended for making garments are finished for better dimensional stability.
Thermal Properties: Wool is not a good conductor of heat as it can hold air due to its crimpy structure. When made into woolen fabric, numerous air spaces withhold the heat, thus making it suitable for blankets.
Wool fibre shrinks away when exposed to flame. It takes up flame and burns very slowly. It is self extinguishing when removed from flame and gives burnt hair smell. It leaves a black crushable bead as residue. As it does not support combustion, it used for fire resistant fabrics.
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