Polymer such as rubber, suberin, melanin and lignin. Naturally occurring polymers such as cotton, starch and rubber were familiar materials for years before synthetic polymers such as polyethene and perspex appeared on the market. Many commercially important polymers are synthesized by chemical modification of naturally occurring polymers. Prominent examples include the reaction of nitric acid and cellulose to form nitrocellulose and the formation of vulcanized rubber by heating natural rubber in the presence of sulfur. Ways in which polymers can be modified include oxidation, cross-linking and endcapping. Especially in the production of polymers the gas separation by membranes has acquired increasing
Union Sulphur Company land. He assumed that the sulfur deposits extended laterally underneath his property, and he planned to extract the sulfur with a new method. He would insert three pipes down into the sulfur. Super-heated water would be pumped down one pipe to melt the sulfur, and compressed air would be pumped down another pipe. The increased pressure from the compressed air would then force the molten sulfur up through the empty third pipe. Upon drilling on his property, however, Frasch discovered that the sulfur was only located beneath the American Sulphur Company property. The American Sulfur Company was not a fly-by-night