Macro and Micro structure of Wool Fiber

Surface of Wool Fiber

The Macro Structure of Wool : 

The wool fiber is crimped, fine to thick, regular fiber. As the diameter of the wool fiber increases the crimp per unit length decreases. 

Length---------------(1.5 to15) -------------(3.8----------38)

Diameter------Fine 14um, coarse 45um,

Length width ration ------------2500:1 for the fine and shorter, 7500:1 for coarse and longer

Color --------------Off white, and light cream.

Crimp ---------------Fine wool 10 crimp/cm, coarse wool 4 crimp/cm

# Physical Properties of wool

1. Specific Gravity : 1.31
2. Moisture Regain : (13-16)%
3. strength-> Tenacity--> Dry : 1.35 g/d
4. Elasticity--> Breaking extension : 42.5%
5. Feel ----> Soft
6. Resiliency : Excellent
7. Abrasion resistance : good
8. Dimensional Stability : bad

# Why do we feel warm by wool cloth : The crimped configuration prevents wool fibers from aligning themselves too closely when being spun into yarn. As a result it is possible to have wool textile materials with air spaces. Occupying about two-third of the volume. The warmth of wool fabric is due more to the air spaces in the material then to fiber.

Micro Structure of Wool :

The micro structure of wool fiber consists of three main components, the cuticle, cortex and medulla.

1. Cuticle : The cuticle is the layer of overlapping epithelial cell's surrounding the wool fiber. There are three cuticle.
• Epi-Cuticle
• Exo-Cuticle
• Endo-Cuticle
• Epi Cuticle: The epicuticle is the outermost layer covers of the wool fiber
• Exocuticle : The overlapping epithelial cell forms the exocuticle.
• Endocuticle: The endocuticle is the intermediate connecting layer bonding the epithelial cell of the cortex of the wool fiber.
2. The Cortex: The cortex or core, of the fiber forms about 90% of the fiber volume. It consists of countless spindle shaped. It is composed of cortex known as ortho and para cortex. The ortho cortex absorbing more dye than para cortex. The ortho and para cortex spiral around one another.
3. Medulla: Coarser fiber have a hallow space running lengthwise through the center. This is medulla.