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Manufacture of synthetic rubberThe successful industrial synthesis of rubber is the most significant achievement of the science and technology of XX century. Needs of the industry obviously have surpassed natural opportunity of the rubber plants. Synthesis of rubber in large factory scale for the first time in the world has been carried out in 1932 in the USSR by S.V.Lebedev. In 1938 manufacture of synthetic rubber was organized in Germany, in 1942 - in the USA. By 1972 synthetic rubber was produced in more than 20 countries. S.V.Lebedev followed the path of imitation of nature. Natural rubber is a polymer of diene hydrocarbon, and S.V.Lebedev used diene hydrocarbon as well, but more simple and accessible – butadiene. As a raw material for production of butadiene was ethyl alcohol. Produced synthetic was similar to natural rubber and even surpassed it on separate parameters. But natural rubber is more elastic than synthetic rubber and the elasticity is the most important property at manufacturing automobile and aviation trunks. The further researches have shown that natural rubber has stereoregular structure, groups -CH2- in macromolecules of rubber are located on the one side of a double connection in each part, not randomly, i.e. are in cis-position. Such position of groups -CH2- promotes natural twist of the macromolecule into a ball that causes high elasticity of rubber. In case of trance-structure of parts the macromolecule appears more extended and don’t possess such an elasticity. At synthesis the stereoregular structure was impossible, but nevertheless the problem managed to be solved owing to the catalyst (metal sodium) which provides the stereoregular structure in a growing polymeric chain. As a result synthetic rubber looks like natural one; it possesses good water-and gas tightness. For increase of durability and elasticity it is subjected to vulcanization as well as natural rubber. Wide use of butadiene rubber for the manufacture of various rubber products has caused serious changes in a raw-material base of the manufacture of rubber. Before as a raw material for butadiene they used ethanol which was produced from grain and potatoes. Interests of the economy demanded more accessible sources of the raw material, therefore nowadays for synthesis of rubber the hydrocarbons containing in oil gases and in products of oil refining are used. Just as natural rubber is got from latex, synthetic rubber is got from synthetic latex. It is produced from two basic substances: butadiene-1,3 and sterol. Butadiene-1,3 is the gas got from oil, and sterol - a liquid extracted from oil and coal. Butadiene-1,3 and sterol are placed in the great containers with a soap solution which facilitates process of formation of parts of rubber. Catalysts are added. After mixing up it gradually turns to a liquid of dairy color - synthetic latex which is externally very similar with natural. When synthetic latex gets the necessary standard, stopping reaction inhibitors are added. Then latex is placed into other container with an acid and a hydrochloric solution where latex is curtailed. The curtailed slices of rubber look like grey grains, which subsequently are washed to remove unnecessary chemical substances. The synthetic rubber is dried and pressed in granules. There are different kinds of synthetic rubber. They are produced with addition of various substances or their connection. |
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