Fiber, Synthetic
Uses for synthetic fibers range from nylon stockings and clothing to cables and tire reinforcement. Synthetic fibers are made from polymers that are either melted into a solution by heat or dissolved by a solvent. The solution is then passed through a metal plate with fine holes, called spinnerets. This process forms the polymers into strands. The fibers are then either cooled or passed through a jet of air to allow the solvent to evaporate. Most fibers at this point are subjected to cold drawing, a strengthening technique developed by Wallace Carothers's team in its search for artificial silk. After drawing, the fibers are washed, dried, dyed, and woven.
The first patent for synthetic fiber was granted to George Audemars in 1855. A related patent was granted to Sir Joseph Swan in 1880. Both of these men produced fibers from cellulose, which, unfortunately, were not very strong. Louis Comte de Chardonnet later found that by denitrating the fibers he could strengthen them until they were as durable as silk. Edward John Bevan and Charles F. Cross developed the industrial production process for this material, which is called rayon.
Acrylonitrile, which was discovered by Moureau in 1893, is used in the production of nitrile rubber, acrylic fibers, insecticides, and plastics. The fibers formed by acrylonitrile are unstable at their melting point, so melt extrusion is impractical. Solution spinning was not possible for many years because no appropriate solvent had been found. Today cold drawing is used to strengthen the fibers by orienting the molecules and allowing hydrogen bonding to occur. The fibers are then dried and woven into a fabric that resembles soft wool, which is used for sails, cords, blankets, and clothing.
Nylon was developed by DuPont Company researchers as a substitute for silk. Carothers and his team of assistants had been researching long chain polyesters and polyamides. In 1938 they had almost given up on finding a suitable fiber when two members of the team discovered cold drawing. Nylon is used in clothing, laces, tooth brushes, sails, fish nets, and carpets.
John Whinfield and J. Dickson continued Carothers's research and made a polyester with terephalic acid in 1941. The fiber was christened terylene and marketed as Dacron in the U.S. by the DuPont Company. Acrilan, produced by the Chemstrand Corporation, is an acrylic fiber used in fabrics and may be blended with wool or cotton to form clothing, carpeting, linens, draperies and upholstery. Fabrics made from acrilan resist mildew, moths, and wrinkling. They also tend to dry quickly.
Orlon is a class of synthetic fibers first produced commercially by the DuPont Company in 1950. The fibers vary in size, texture, and ability to hold dyes. They can be woven or knitted, usually into bulky garments. Orlon is used in upholstery and carpets.
Vinyon filaments and fibers were developed by the Carbide and Carbon Chemicals Corporation, which licensed American Viscose Corporation to produce them in 1939. The fiber is a copolymer of 88 percent vinyl chloride and 12 percent vinyl acetate. It was the first plastic fiber produced on a large scale in the United States. The fibers are stretched in a process similar to cold drawing. The stretching increases the strength of the fiber but lowers its elasticity. The fiber does not take dyes and becomes sticky if heated to over 149° F (65° C). At 167° F (75° C). garments made of the fiber will shrink. Further research led to the development of a fiber Vinyon N, which is a copolymer of vinyl chloride with acrylonitrile. For fibers, the copolymer ranges from fifty-six to sixty percent copolymerized vinyl chloride. It was patented in 1947.
Kevlar is a polyamide fiber developed by Stephanie Kwolek of DuPont in 1965. It is incredibly strong due to its molecular structure of alternating aromatic rings and amide groups crosslinked by hydrogen bonding. Kevlar's light weight and high strength make it very marketable. It is commonly used to make bulletproof vests.
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