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Rubber sheet processing

( Update: 12/09/2014 )

Natural rubber is coagulated latex from certain types of trees that grow in the tropics. Synthetic rubber is manufactured in a factory. Rubber got its name when English scientist Joseph Priestly observed that it could "rub out" pencil marks [source: RMA].

Rubber is a polymer, which is a chain of monomers, or small molecules. Natural rubber has only monomers of isoprene, while synthetic rubber can contain any of several types of monomer, but those must be derived from petroleum. The processors mix different chemicals with the rubber, depending on its ultimate use. In 1839, U.S. inventor Charles Goodyear determined that heating rubber with sulfur resulted in a stronger product that was more stable over a wide range of temperatures. He called this process vulcanization and further discovered that he could quicken the process by adding other substances. Vulcanization strengthens rubber because the sulfur links the polymer chains into a stronger matrix.

Natural rubber is processed by first taking the sap from a cut in the tree. Next, processors flatten it into sheets. To make the sheets, workers blend latex from various sources and sometimes mix it with water and coagulants. Then the latex is passed through grooved rollers to produce sheets of rubber that are allowed to dry. On small rubber plantations, these sheets are visually inspected; they're tested technically in larger operations. After imperfections are removed, the sheets are baled together with talc in between to keep them from sticking to each other. Block rubber goes through the same initial stages, but is chopped up and pressed into bales [source: UNCTAD].

Synthetic rubber is made by mixing two by-products of petroleum refining, butadiene and styrene. They are mixed with soapsuds to make liquid latex, which is then dried into bits and pressed into bales. About 70 percent of all rubber is synthetic. The industry can vary the chemical formula of synthetic rubber to adapt it to different applications

Martha Barksdale - http://curiosity.discovery.com/q