Silk
Fibre structure & physical properties
Fibre composition:
Protein
Diameter: 10-13 μm
Very fine: < 10 μm,
Fine: < 20 μm,
Medium: 20-50 μm,
Course: > 50 μm
Length: Filament
Staple length: 500 - 1500 metres
short < 26 mm,
medium 26-29 mm,
long: 30-38 mm,
extra long: 39 mm and over
Natural fibre colour: Cultivated silk is white; Wild silk is yellow or brown.
Microscopic Images (Cross sectional and SEM):
Cross-sectional view of silk fibres (courtesy of Dr Jinsong Shen, TEAM Research Group, De Montfort University, Leicester, UK) – http://docplayer.net/163742387-Textile-fibres-textile-technology-knowledge-series-volume-i.html
Caption:Cultivated silk is finer, more even, triangular shaped with rounded corners cross section
Wild silk is less even, rectangular cross section
Comment:
Smooth, flat surfaces of the fibrils reflect light giving silk a natural sheen (lustre); wild silk broader fibre with fine, longitudinal lines passing across the filament.
Fibre properties (Mechanical, Chemical and Thermal)
Mechanical Properties
Tensile strength (cN/dtex) : 2.6-3.5 dry 1.9-2.5 wet
Chemical Properties
Hydrophobicity: Hydrophilic
Moisture regain (%): 11%
Thermal Properties
Flammability: Silk is a protein fibre which behalves in a similar manner to wool when burnt. Silk can be difficult to ignite, tends to burn slowly, and smells like burning hair. The odour from wool is often less intense than that from silk. The ash is greyish-black and
Sustainability considerations
Silk is biodegradable; however there are ethical and ecological issues with cultivated silk. Wild silk (tussah) meets high ethical and environmental standards (until the dyeing stage). The tussah silkworm leaves a small hole when spinning its cocoon as an escape route, enabling longer filaments to be obtained. Colours are limited to the natural brown palette.
End uses
Apparel: underwear, luxury outerwear, gloves, linings, ties; good to humid climates.
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.
