Wallace H. Carothers was born on April 27, 1896 in Berlington, Iowa. He graduated from Terkin College with a bachelor of science in 1920, and earned his Ph.D. in 1924 from the University of Illinois. For a short time Carothers taught at the University of Illinois and at Harvard University. Because he preferred research to teaching, Carothers accepted a position with Du Pont in 1928to work on a basic research program. Until then, Du Pont had simply bought the technologies developed by others. In order to diversify, Du Pont decided tomake a commitment to fundamental research. Carothers was asked to research polymer chemistry. It was felt that by discovering the underlying properties and structures of polymers, Du Pont could develop synthetic substitutes for natural products. There were various theories on the structures of polymers. Carothers supported the theory that polymers were large molecules made up of repeating units. He developed a research plan and in 1930 succeeded in provingthat polymers are macromolecules, thus laying the foundation for modern polymer science. With his research team, Carothers went on to develop a substitutefor rubber called neoprene. Natural rubber is a polymer of isoprene. Neoprene was made with a chemical of a similar structure called chlorprene. Althoughit was more expensive than natural rubber, neoprene proved more resistant tosun, weather, ozone, oil, and gasoline. First marketed in 1930, it is stillused in hoses, shoe soles, gaskets, drive belts, wet suits, and cable jacketing. Carothers's research team then began to experiment with polymer fibers toreplace silk. They started with polyamides but soon went on to work with polyester. During experimentation with the polyesters, one of the researchers drew the polymer out into strands and noticed its silky appearance. Because oftheir earlier research the team realized that stretching the material oriented the polymer molecules. There was one problem, however. Polyesters melt at temperatures too low for use in the textile industry. Nylon, a polyamide, hasa higher melting point. The team repeated the experiment with nylon and had greater success forming fibers. Industrially, nylon is forced through small holes to form fibers and then stretched by passing it through a pair of rollersrotating at different speeds. This process, called cold drawing, stretches the fiber several hundred percent and increases the strength of nylon by morethan 90 percent. Nylon is used in guitar strings and fabric blends where, with proper treatment, it resembles wool, silk, or cotton. Debuting as stockingsin 1938, nylon was the first commercially successful synthetic fiber. Nylonis resistant to heat, oils, grease, and water, and is used in apparel, carpets, and tire cords. As substitutes for rubber and silk, both neoprene and nylon became very important during World War II, when these natural products werein short supply. Carothers contributed more to our basic understanding of polymer science than anyone else. Sadly, Carothers did not live to see the global impact of his discoveries; he committed suicide in 1937.
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