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
Sulphur, Louisiana Sulphur, Louisiana Sulphur () is a city in Calcasieu Parish, Louisiana, United States. The population was 20,410 at the 2010 census. Sulphur is part of the Lake Charles Metropolitan Statistical Area. Sulphur is named for the sulfur mines that were operated in the area in the 1900s. In 1867, Professor Eugene W. Hilgard, an experienced geologist who was prospecting for oil and other minerals, conducted exploratory borings in Calcasieu Parish, Louisiana and discovered sulfur in the caprock of a salt dome. However, the sulfur was beneath several hundred feet of muck and quicksand containing deadly hydrogen sulfide gas, which made