Fibers Flashcards
How many layers does the coat of wild sheep have, one or two?
Two.
What is the outer coat of wild sheep composed of?
Coarse, medullated hair.
What is the inner coat of wild sheep composed of?
- Wool.
- A heterotype fiber intermediate between hair and wool.
What did wool producers select against the presence of in the coat of sheep, resulting in its removal?
Guard hair.
What are the two types of wool follicles?
- Primary follicles.
- Secondary follicles.
What are the characteristics of the primary wool follicle?
- Largest.
- Develops first.
- Develop in trios.
What are the characteristics of the secondary wool follicles?
- Produces smaller, finer fiber.
- Develop later than primary follicles, but mature after birth.
- Lack sweat glands and arrector pili muscle.
What is the correlation between the number of primary follicles and the number of secondary follicles as the sheep ages?
Negative, the number of primary decreases as the number of secondary increases.
What breed of sheep have the finest wool?
Merino.
What makes wool different than hair?
- Lack of medullation.
- Crimping.
- Diameter of an individual strand (17-40 microns).
What is hair, gare, heterotype, or med in sheep?
Fiber produced by sheep that lacks crimp.
*Difficult to detect with the unaided eye.
What is kemp?
Brittle, chalky white, coarse, short, >50 microns fiber that does not accept dyes.
What fabric is kemp used to make?
Tweed.
What is the thermal property of wool?
An excellent insulator and rapidly wicks moisture away from the body.
What is the moisture property of wool?
Wool can absorb up to 34% of its dry weight in moisture before feeling damp.
What is the elasticity property of wool?
The molecular structure and crimping.
What is the strength property of wool?
Possess 62-80% of the tensile strength of human hair.
What is the electric property of wool?
Poor conductor of all electricity except for static.
What is the fire resistance property of wool?
Wool burns, but only if held in the flame, otherwise it will self extinguish.
What is the acid resistance property of wool?
Wool is generally resistant to acids, except for concentrated and/or hot ones. These are used to hydrolyze wool.
How does wool react to exposure to bases?
Strong bases hydrolyze wool.
How does wool react to exposure to sunlight?
UV light yellows or browns the wool and results in frowzy tips.
How does wool react to exposure to heat?
At temperatures of 212+ F, yellowing, browning, NH4 release, and HS release occur.
How does wool react to exposure to cold?
When exposed to extreme cold (liquid nitrogen cold), wool becomes brittle.