lecture 8 - textile fibers examination

Why are fibers interesting physical clues?

Why are fibers interesting physical clues?

- extreme variability
- high sheddability during contacts and persistence
- Physical and chemical properties exploitable using analytical methods

What is the definition for a textile fiber?

Natural or man made substances which are twisted into yarns, and then woven into textile fabrics

What is the definition of yarns?

Strand of textile in a form suitable for wearing, knitting, braiding, felting, webbing or other fabricating into a fabric

What microscope is used for searching fiber on tape?

Stereomicroscope

What is the name of the taping method that details application of multiple numbered/coded adhesive tapes on a dead body?

1:1 taping

What are the three general textile fibers classification?

— Natural

• ANIMAL

• Vegetable

• Mineral

  Man made

What are the second most widey used natural fibers?

Animal fibers

Animal fibers from what?

Fleece of mammals (hair)

T/F
Animal fibers are protein based

TRUE

What is the main protein of animal fibers:

Keratin
- amino acids with disulfide bridges

What are some animal fibers with the most significant economic value in textile market today?

Wool, morhair, angora rabbit, cashmere, alpaca wool and cultivated silk

What is a microscopic feature of animal fibers?

Presence of scales

What two animal fibers are usually difficult to distinguish?

Lamb wool and angora rabbit

From where is silk obtained from?

Cocoons of several types of caterpillar or silkworm

What two proteins does the silk emitted by the silkworm consist of?

- Fibroin (structural center of the silk)
- Sericin (sticky material surrounding it)

What amino acids largely madke up fibroin?

Gly-Ser-Gly-Ala-Gly-Ala

What is the principle series of silk?

Cultivated mulberry silk

What are the three groups that vegetable fibers are classified into?

- Seed: cotton, kapok, coir
-Bast or stem: flax or linen, jute, ramie, hemp, kenaf
- Leaf: sisal, abaca

What are the three structure polymers that compose vegetable fibers?

- Cellulose, hemicellulose and the aromatic polymer

What is the most prevalent natural fiber encountered in forensic lab?

COTTON

t/f
Cotton contains 90% cellulose

TRUE

With what microscope is cotton easily identifiable?

Polarizing light microscope