Wool Fiber || Physical And Chemical Properties Of Wool

Wool is a protein fiber and it is formed in the skin of sheep and hence it is called animal fiber. It is produced from different types of sheep all over the world. Now days, it is a very important textile fiber in the textile sector.

Like all the textile fibers, Wool has its own physical and chemical properties which are required to know for better processing in spinning, weaving, knitting, dyeing, printing as well as finishing. Here, I have written about physical and chemical properties of wool fiber.

Physical Properties of Cotton: Physical properties of wool fibers are given below:

  1. Color: The color of wool fiber could be white, near white, brown and black.
  2. Tensile Strength: The tensile strength of wool in dry condition is 1 – 1.7 and 0.8 – 1.6 in wet condition.
  3. Elongation at break: Standard elongation is 25 – 35% and 25 – 50% in wet condition.
  4. Elastic Recovery: Good
  5. Specific Gravity: Specific gravity is 1.3 – 1.32.
  6. Moisture Regain (MR %): Standard moisture regain is 16 – 18%.
  7. Resiliency: Excellent.
  8. Luster: Luster of course fiber is higher than fine fiber.
  9. Effect of Heat: Heat affects the wool fiber greatly. Wool becomes weak for heat. It softness when heated or treated with boiling water for long time. At 1300C it decomposes and chars at 3000C. Wool does not continue to burn when it is remove from a flame.
  10. Effect of Sun Light: The main chemical components (keratin) of wool decomposes under the action of sun light. The sulpher in wool is converted into H2SO4. The fibers become discolored and develop a harsh feel.
  11. Stored: No problem.

Chemical Properties of Cotton: Wool is a protein fiber and it has some chemical properties. Chemical properties of the wool fiber are given below:

  1. Effect of Acids: Wool is attacked by hot concentrated sulphuric acid and decomposes completely. It is in general resistant to mineral acids of all strength even at high temperature though nitric acids tend to cause damage by oxidation. Dilute acids are used for removing cotton from mixtures of two fibers; Sulphuric acid is used to remove vegetable matter in the carbonizing process.
  2. Effects of Alkalis: The chemical nature of wool keratin is such that it is particularly sensitive to alkaline substances. Wool will dissolve in caustic soda solutions that would have little effects on cotton. Strong alkaline affect on wool fiber but weak alkaline does not affect wool.
  3. Effect of Organic Solvent: Wool does not affect in organic solvents.
  4. Effects of Insects: Wool affected by insects.
  5. Effect of Micro Organism: It affected by mildew if it remains wet for long time.
  6. Dyeing ability: Wool fiber could be dyed by basic dye, direct dye and acid dye.

It is noted that; all the wool fiber is not same in characteristics. It varies depending on the wool’s country of origin and sheep type.

So, choose your wool fiber after confirming about the physical and chemical properties of wool fiber.

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