Styrene-Butadiene Rubbers

Abstract

More than half of the world’s synthetic rubber is styrene-butadiene rubber (SBR). World usage of SBR is about the same as that of natural rubber: between eight and nine billion pounds of each (see Fig. 7.1 and Tables 7.1 and 7.2). The factors accounting for this dominance are economic and technological: (1) the availability of styrene and butadiene precursors in fossil hydrocarbons makes these two monomers preeminent among the possible sources of synthetic rubber, and (2) they can be combined in rubber compounds that can be processed conveniently in tire molds, where thermal treatment converts them into tires. Much of the modern world’s transportation relies on these durable, tough elastic composites. In fact, the tire industry has come to depend on SBR more than on natural rubber, partly because the latter has at times been harder to get, and partly because SBR often is better for the purpose required. Similarly, other synthetic rubbers have competed on the basis of both availability and technological utility; in some cases, they have even found niches, but lesser ones. It is instructive to examine history, searching for the reasons SBR has won its dominance, especially at a time when its share of the market is declining.