Chemical composition of wool


  
Chemical composition of wool



The composition of raw wool will vary greatly because of the many complicated factors. The important constituent is known as keratin. It differs from others on account of its high sulfur content. The compositions of raw wool are shown.
Chemical compositions in wool fibre

    Composition   Percentage (%)
  1.     Keratin                    45-75
  2.     Grease                    5-15
  3.     Moisture                  10-12
  4.     Suint                        2-12
  5.     Sand and dirt           4-30
  6.     Vegetable matter     0-5


Grease


It is an impurity in raw wool, insoluble in water but can be partially emulsified by it. It is soluble in organic solvents. Wool grease is an ester of high molecular weight fatty acids and a monohydric alcohol i.e. cholesterol (C27 H45OH) or is cholesterol. This is not fat but wax. Wool wax has the power of absorbing large quantities of water.


Suint

This is soluble in water and can be isolated from the raw wool by aqueous extraction. It consists of potassium salts of fatty acids and organic amino acids and is a complex mixture.

Sand and dirt

The fibre in its natural state contains a considerable amount of dirt. This is held by adhesive action of the grease and falls away when the latter is removed during scouring. Wool keratin is composed of fine elements, carbon, hydrogen, nitrogen, oxygen, and sulfur.

The compositions are :
  1. Carbon     50-53%
  2. hydrogen  6-7%
  3. Nitrogen   16-18%
  4. Oxygen   21-25%
  5. Sulfur      7-5.0%


The element of the composition of keratin is nearly the same for a different type of wool but the sulfur content varied within great limits. Most of the stability and instability of wool depend upon functional nitrogen and sulfur group

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