Fiber Evidence

Background:

In forensic science, fiber evidence can be used to trace evidence from a crime scene to an offender responsible for a crime. The main problem with fiber evidence is that it can be very difficult to identify an offender since most fibers do not have a distinct difference between them. Fibers can be classified as natural, synthetic, or semi-synthetic based off of the fiber was formed. A natural fiber is produced entirely by a plant or animal. One example of a natural fiber is silk, which was accidentally discovered by the wife of the Yellow Emperor, Hsi Ling Shi. According to legend, a cocoon fell from the tree above her and unraveled, allowing her to discover the Bombyx mori silkworm. After her discovery she developed the cultivation of silkworms called sericulture (History of Silk, 2012). China had a monopoly on silk trade for thousands of years and arranged the Silk Road; which expanded the trade of silk and other products all over the world. Silk was not available America until the 17th century and today its main producers include China, Japan, India, and Italy (Silk Painting Gallery, n.d.). Silk was used for production of clothing, musical instruments, bow-making, and used as decorations in higher class families (Silk Road China, 2013).

Silk can be produced from other insects but moth caterpillars are the main contributor to the textile manufacturing of silk since they create a much smoother and finer fabric (Silk History, n.d.). The cocoons are raised by the farmer and are delivered to the factory, or filature, where the silk is unwound from the cocoons and the threads are collected into coils. When the filature receives the cocoons they must sort them according to color, size, shape, and texture. They then put t...

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... and react to form a prepolymer. In dry spinning fiber production, the prepolymer is additionally reacted with an equal amount of diamine. The resulting solution is diluted with a solvent to produce the spinning solution. The spinning dry solution is pumped into a spinning cell where it is converted into fibers by forcing the polymer solution through a spinneret. This causes the solution to be aligned in strands of liquid polymer. As the strands pass through, they are heated in the presence of a nitrogen and solvent gas, causing the liquid polymer to chemically react and form solid strands. The fibers are then treated with a finishing agent that prevents the fibers from sticking together. The fibers are transferred through a series of rollers onto a spool. When the spools are full they are put into final packaging and shipped to textile manufacturers and customers.