Wool
Fibre structure & physical properties
Fibre composition:
Protein
Diameter: 12–60 micrometers
Very fine: < 10 μm,
Fine: < 20 μm,
Medium: 20-50 μm,
Course: > 50 μm
Length: Staple
Staple length: Short - Extra long (30 - 250mm). For example, Corriedale : 80-120 mm, Devon: 200-250mm. Length is dependant on the location on the animal from which the fibre is taken and the duration of growth.
short < 26 mm,
medium 26-29 mm,
long: 30-38 mm,
extra long: 39 mm and over
Natural fibre colour: Animal hair, including sheep's wool, alpaca, angora, cashmere, camel and vicuña is available in a range of colours, typically brown, grey, white and black.
Microscopic Images (Cross sectional and SEM):
By CSIRO, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=35442281
Caption:The bulk of the animal hair fibre is called the cortex. This is made up of millions of long cortical cells (fibrils) held together by a strong natural binding material. These cortical cells can slide over each other, making stretch and recovery a characteristic of animal fibres. In some wool’s, Merino particularly, the cortex is composed of two parts (ortho- and para-). These grow at different rates, pushing the fibre into waves (crimp).
Comment:
Outer layer of overlapping scales, all pointing to the tip of the fibre.
Fibre properties (Mechanical, Chemical and Thermal)
Mechanical Properties
Tensile strength (cN/dtex) : 0.9-1.5 dry, 0.7-1.4 wet
Chemical Properties
Hydrophobicity: Hydrophilic
Moisture regain (%): 15-16
Thermal Properties
Flammability: Animal hair, including sheep's wool, alpaca, angora, cashmere, camel and vicuña, can be difficult to ignite, tends to burn slowly, and smells like burning hair. The ash is blackish and easily crushed.
Sustainability considerations
Animal hair, including sheeps wool, alpaca, angora, cahmere, camel and vicuña, is ecologically sustainable, self-renewing sources of fibre which grow continually and can be shorn from the animal without harm? But with increased intensive farming methods there are certain issues of animal welfare and pesticides – i.e. mulesing.
Organic wool – produced using not chemicals and animal welfare is a priority.
End uses
Apparel: Underwear (insulation, moisture absorbent); Outerwear – suits, knitwear, coats (abrasion resistance, stretch & recovery, insulation)
Furnishing: Carpets (stretch & recovery, abrasion resistance); Upholstery, curtains, curtains, screens (abrasion resistance, low flammability)
Videos
Materials using this fibre
Additional resources
Taylor MA, 2004. Technology of Textile Properties. Third edition. Forbes Publications, London, UK.
Zhong Z and Xiao C, 2008. Fabric composition and testing. In: Fabric Testing. Ed: Hu, J. Woodhead Publishing Limited, Cambridge, UK.
ISO/TR 11827:2012 Textiles — Composition testing — Identification of fibres.
Houck, Max M. Identification of Textile Fibers. Cambridge : Boca Raton: Woodhead Pub. in Association with The Textile Institute ; CRC, 2009. Print.
