Chemical Reactions of Rubber

Most of the literature descriptive of the various known derivatives of rubber is found published as patents rather than as technical papers, thus indicating the commercial possibilities that may be expected from these developments. Fisher, Schidrowitz and, more recently, Jones have summarized and discussed the chemistry of rubber and its commercial derivatives. The decomposition of rubber by heat has been studied by several investigators. Williams showed that isoprene is one of the main products formed by the destructive distillation of either caoutchouc or gutta percha. Later investigators have shown that slow heating in vacuo at 300° C converts somewhat more than one-half of rubber hydrocarbon into a solid, thermoplastic, isomeric product, which has a high molecular weight and less unsaturation than that of the original hydrocarbon. Rapid heating, especially in vacuo, converts almost all the rubber into volatile products. The most complete investigation of the products obtained by the heat decomposition of rubber apparently was carried out by Midgley and Henne. These investigators destructively distilled 200 pounds of pale crepe rubber in 16-pound batches by raising the temperature as rapidly as possible to 700° C at atmospheric pressure in an iron kettle. The condensate was fractionally distilled, and cuts were made every degree between 50 to 176° C. Each cut was then separately examined. Twenty-three different hydrocarbons were identified in the distillate.