The Chemistry of Rubber the Interaction of Ethylenic Compounds and Rubber

It is known that the hydrocarbon of rubber has an ethylenic structure; its chemical reactions, the basic principles of which were brought out in 1902 by Weber, and which were the object, in 1930, of important work by Fisher, show that it has the general properties of ethylene derivatives, including the addition of hydrogen and metalloids of the first group (chlorine and bromine in particular), the addition of hydracids, scission by ozone, autoxidation, and isomerization by means of catalysts which isomerize ethylene derivatives, such as sulfuric acid and chlorides of metalloids. However, aside from these general reactions, rubber hydrocarbon reacts in other ways which likewise depend on the unsaturation of the molecule and on the macromolecular structure, and which in this particular case are of prime importance because it is on these properties that the processing and applications of rubber depend. As a good example, a fundamental change results from the action of sulfur, viz., vulcanization, whereby rubber passes from a predominantly plastic state to a predominantly elastic state, a change which is manifest by the rubber becoming insoluble. Moreover, sulfur is not the only agent which is capable of bringing about vulcanization; in fact, it has been found that many other agents are capable of vulcanizing rubber. Although Goodyear discovered this reaction in 1839, there is still no general agreement as to the mechanism of vulcanization; however, vulcanization is at present regarded as the transformation of an agglomerate of filiform molecules into a three-dimensional network.