Fibers

fibers

are the smallest indivisible unit of a textile, it must be at least 100 times longer than wide. Fibers are twisted together to make up yarn.

textile

a flexible, flat material made by interlacing yarns (or threads)

crystalline

fibers composed of polymers packed side by side in a repeated pattern, usually stiff and strong

polymer

A substance composed of long chains of repeating molecules

monomer

Small, repeating molecules that can link to form polymers

yarn

Fibers that have been spun together

direct transfer

is the transferring of particles or fibers when the suspect and victim come into direct contact

Secondary Transfer

when fibers are picked up by a victim at an earlier time and then transferred to a suspect

natural fibers

are any and all fibers that originate from animals, plants and minerals taken directly from the ground.

animal fibers

These contain fur, hair, and webbing. They all contain proteins in their composition and have many uses including but not limited to clothing, carpets, drapes, and bedding. Although usually associated with hair or fur, some fabrics such as silk is woven from webbing from a silk worm.

plant fibers

fibers made up of plants cells. They are grouped by the part of the plant they come from, like seed, stem, fruit, and leaves.

stem fibers

include hemp, jute, and flax

mineral fibers

Produced from industrial processing of mined materials. They include fiberglass and asbestos

synthetic fibers

fibers made from petroleum based polymers or regenerated natural fibers.

regenerated fibers

are those that are changed through chemical processing of natural cellulose fibers to form rayon and other light weight fabrics

synthetic polymers

polymers that are made from petroleum products and are long polymers

polyester

a common synthetic fiber used in many clothing types. Can be made with recycled plastics.

nylon

is lighter yet similar to polyester except that it breaks down easily in light and acids

warp

longitude part of weave (stronger part of weave)

thread count

In a woven fabric, the number of warp threads plus the number of weft threads per square inch. Example 100 warp threads plus 150 weft threads gives a thread count of 250.

burn test

reaction to heat, manner of burning, smoke color and odor, type of residue. Often synthetic fibers melt.

gathering fibers

forensic scientists may use fiber vacuum, sticky tape or tweezers.

disadvantages of synthetic fibers

they can deteriorate in bright sunlight and melt at a lower temperature than natural fibers.

asbestos

the mineral fiber from this rock is used in break pads, fire retardant coatings, ceiling tiles, pipe insulation and more.

weave patterns

plain, basket, satin, twill are common ones

early collection

necessary because 95% of fibers are lost in the first 24 hours.

weft

the term for the thread or yarn which is drawn through, inserted over-and-under, the lengthwise warp yarns that are held in tension on a frame or loom to create cloth