Petroleum Plastics
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Petroleum Plastics Crude petroleum pumped out of the ground contains thousands of different chemical compounds. These compounds include semisolid materials such as paraffin wax and asphalt, as well as gases dissolved in the heavier components under extreme pressure conditions deep beneath the earth. When the crude petroleum is brought to the surface and atmospheric pressure, these gases boil out to become "natural gas." Over 3,000 different substances are prepared from crude petroleum. Refineries convert the crude into end products and intermediate products including natural gases, gasolines, solvents, kerosenes, asphalts, vaselines, medicinal oils, and petrochemicals. Though petrochemicals account for only about 5% of the world's oil production', their importance in manufacturing is disproportionate. Petrochemicals are used to make adhesives, surface coatings, drugs, pesticides, and fertilizers. About half of the petrochemicals produced, however, are used to manufacture plastics, particularly polyethylene, polypropylene, polystyrene, and vinyl, and also synthetic fibers such as nylon, polyester, acrylic and acetate, and synthetic rubbers such as styrenebutadiene, butyl, nitrile and polychloroprene. Originally, simple refining of crude oil was enough to separate natural gas and gasolines consisting of only a few hydrocarbons by distilling crude petroleum through fractionation columns. Early refining processes could separate methane, ethane, propane, butane, isobutane, and pentanes. More sophisticated fractionating columns could further isolate petroleum compounds with similar boiling points. The petrochemical industry began primarily in the United States. Before 1920, the only petrochemical widely available was carbon black, which had been manufactured from natural gas since the 1870s. Interest in petrochemicals was stirred during World War I, when wartime activities caused shortages of many chemicals for civilian and military uses. Primary among these was toluene necessary for the manufacture of explosives, such as trinitrotoluene or TNT; several U.S. refineries altered their processes to emphasize production of toluene to the detriment of other petrochemicals. Thermal "cracking" (conversion of heavy fractions to light fractions) of propane to produce ethylene also became
commercially feasible in the early 1920s. Ethylene, along with butylene and propylene, became a primary petrochemical through the 1930s. The demand for ethylene and propylene grew so exorbitant that ambitious new cracking processes were developed to increase the proportion of these molecules. A single modern cracking plant can produce a billion pounds of ethylene a year. E.W. Fawcett and R.O. Gibson at Imperial Chemical Industries in Great Britain developed high-pressure technology in 1934 that allowed them to be the first to polymerize ethylene. Commercial production of their "polyethylene" began in 1939. Plastics developed from ethylene established entirely new markets and displaced existing natural materials including wood and metals. Ethylen
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