Natural Protein Fibres
The protein fibers are formed by natural animal sources through condensation of a-amino acids to form repeating polyamide units with a various substituent on the a-carbon atom. In general, protein fibers are fibers of moderate strength, resiliency, and elasticity. They have excellent moisture absorbency and transport characteristics. They do not build up a static charge. Example of some these fibers is Wool, Silk, Mohair, Cashmere etc.
The protein fibers are formed by natural animal sources through condensation of a-amino acids to form repeating polyamide units with various substituents on the a-carbon atom. The sequence and type of amino acids making up the individual protein chains contribute to the overall properties of the resultant fiber. Two major classes of natural protein fibers exist and include
- Keratin (hair or fur) and
- Secreted (insect) fibers.
In general, protein fibers are fibers of moderate strength, resiliency, and elasticity. They have excellent moisture absorbency and transport characteristics. They do not build up a static charge. While they have fair acid resistance, they are readily attacked by bases and oxidizing agents. They tend to yellow in sun Light due to oxidative attack.
See also: Comprehensive list of Textile Fibers
Major Protein Fiber Sources
Wool is a natural highly crimped protein hair fiber derived from sheep. The fineness and the structure and properties of the wool will depend on the variety of sheep from which it was derived. Major varieties of wool come from Merino, Lincoln, Leicester, Sussex, Cheviot, and other breeds of sheep.
Silk is a natural protein fiber excreted by the moth larva Bombyx mori, better known as the common silkworm. Silk is a fine continuous monofilament fiber of high luster and strength and is highly valued as a prestige fiber. Because of its high cost, it finds very limited use in textiles. A minor amount of wild tussah silk is produced for specialty items.
Mohair is a very resilient hair fiber obtained from the angora goat. The two primary classifications for mohair are the finer kid mohair and the coarser adult mohair. In many respects, mohair resembles wool in structure and possesses properties including the characteristic scale structure of the fiber. The average length of mohair fibers is longer than wool.
Cashmere is the fine, soft inner coat of down obtained from the cashmere goat found on the inner plateaus of Asia. In many ways, the properties of cashmere resemble those of wool, but cashmere fibers are extremely fine and soft compared to wool. Cashmere is used in luxury applications where a soft, warm, fine fiber with beautiful drape is desired.
Llama, Alpaca, and Vicuna
These fibers come from a group of related animals found in South America. They are fine fibers that are white to tan and brown in color. They are longer than most wool fibers and generally stronger, with a finer scale structure. They are generally used only in the expensive luxury items of textiles and apparel.