study guide Flashcards
what are fibers?
the smallest individual unit of a textile; it must be 100 times longer than wide
What is trace evidence?
small but measurable amounts of physical or biological material found at a crime scene.
What is direct transfer?
the passing of evidence, such as a fiber, from victim to suspect or vice versa
what is secondary transfer?
the transfer of evidence, such as a fiber, from a source (for example, a carpet) to a person (suspect), and then to another person (victim)
how are fibers collected?
Fiber evidence can be collected using forceps, tape, vacuums, and even lint rollers
What can fiber evidence reveal
- type of fiber
- fabric color
- numbers of fabric found
- where the fabric was found
what is a textile?
A flexible, flat material made from interlacing yarns (or threads).
what are the 3 sources of animal fiber?
hair, fur, and webbing
Why is animal hair considered a good piece of trace evidence?
because it sheds easier
what polymer makes up all plant fibers?
cellulose
what is monomer?
small, repeating molecules that can link to form polymers
what is polymer?
a substance composed of long chains of repeating molecules.
What are the 4 sources of plant fiber?
seeds, fruits, stems, leaves
what is the difference between amorphous and crystanllie?
Amorphous is without a defined shape; fibers are composed of loose arrangement of polymer that are soft, elastic and absorbing. Crystalline is geometrically shaped; fibers are composed of polymers packed side by side, which makes them stiff and strong.
what are 2 kinds of mineral fiber?
fiberglass and asbestos
what are two types of synthetic fibers?
Regenerated fibers and synthetic polymer fiber
what are the five types of synthetic fibers?
Rayon, nylon, acrylic polyester, and olefins
how do natural and synthetic fibers differ under the microscope?
Natural fibers have an imperfect look and have varying diameter sizes. Synthetic fibers look uniform and have the same diameter sizes, depending on the synthetic fiber.
what happens to fiber if they are too short in their natural state to make textiles?
they are spun into yarn
how are fibers woven into fabrics or textiles?
threads are arranged side by side (the warp ) and more threads ( weft) are given back and forth and crosswise through the warp
what is synthetic fiber?
a fabric made from manufactured substances, such as plastic.
what are 3 sources of natural fiber?
Animals, Plants, and minerals
