Section+1.2A

=Silk =

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=**__Silk__** = Made is from the first habitat of the silkworm, silk originated from China. Silk is made from the cocoon of the worm. While other natural fibers can grow in a nice amount of length silk is the only natural fiber that grows in hundreds of meters long. Silk can also be made from other insect larvae or by spiders to spin webs. Silk is usually associated with luxury and wealth.

Video of silkworms: media type="custom" key="11713470"

(Video taken from: http://science.discovery.com/videos/how-do-they-do-it-7-silk-from-worm-spit.html)

"Silk from wild species is limited in quantity and produce a coarser, stronger, short fiber known as tussah silk. Tussah silk has short fibers because the cocoons from which it is taken have been broken or pierced. When wild silk is spun by caterpillars that feed on oak leaves, the silk is light brown or tan in color and cannot be bleached." (Bide,Collier, Tortora, pp.112)

Silk is one of the strongest natural fibers and stronger than wool. "Its wet strength is slightly less than its dry strength because the hydrogen bonds between protein polymers are broken by moisture." (Bide, Collier, Tortora, pp.116) The resilience of silk is moderate, when wet creases will hang out, but the wrinkle recovery is slow.
 * __// Mechanical Properties //__**

// __**Chemical Properties**__ // Silk is comfortable to wear because the absorbency is fairly good. Because the heat conductivity is low in silk it is a warm fabric. You might have noticed that silk builds up static electricity charges, this is because the electrical conductivity is not high in silk. "Like wool, silk is damaged by dry heat and should be ironed damp, at low temperatures and using a press cloth." (Bide, Collier, Tortora, pp.117) Sweating can cause discoloration after repeat exposure, and for that silk should always be cleaned after each use. It is best to use hydrogen peroxide or any other oxygen bleaches, but do not use chlorine bleach because they cause deteriorates silk.

Mildew and Moth will not harm silk, but carpet beetles love to attack the fabric.Silk should be stored away from sunlight, because it causes silk to deteriorate from white to yellow. As silk ages the strength of the fabric deteriorate, and because of this they should be sealed off from air.
 * //__ Environmental Properties __//**

" The chemical makeup of spider silk is determined not only by the spider species, but also by diet, weather, and other factors. It is similar to silk from silkworms in that it contains no sulfur." (Bide, Collier, Tortora, pp.120) The fibers of spider silk is round in cross section, they also have a higher tenacity and elongation than silk.
 * //__ Spider Silk __//**

Image of Spider Silk:

Make sure to watch the video because some questions for the quiz come from there. Silk Quiz

Footnote: information quoted and paraphrased from (Bide, Collier & Tortora, pp.111- 120).