Synthetic Rubber

Abstract In the early period isoprene was recognized as the mother substance of caoutchouc, and its ability to undergo polymerization to a rubber-like product was demonstrated. During the pre-war period serious efforts were begun to devise processes for the synthesis of rubber which would be commercially feasible. Attention was concentrated on the preparation of the necessary monomeric dienes from cheap raw materials available in substantially unlimited quantity. The rubber-like polymers prepared were markedly inferior to natural rubber. During the war the actual manufacture of synthetic rubber from dimethylbutadiene and its utilization in the production of certain lines of rubber goods was, owing to the exigencies of the time, undertaken in Germany. After a lull, synthetic rubber in 1925 again became an active subject for research. In so far as butadiene and its homologs are concerned, attention during this post-war period has been concentrated on methods of polymerizing the dienes rather than on methods of preparing them, and marked progress has been made. Recently a novel form of synthetic rubber has been prepared by polymerizing 2-chlorobutadiene. Chloroprene rubber resembles vulcanized natural rubber in elastic properties more closely than any previous synthetic rubber preparation and, moreover, has advantages over natural rubber in certain respects. Experiments on the swelling of chloroprene rubber and its tensile properties are reported.