Styrene plastics

Abstract

During the 1939–45 war, supplies of natural rubber were denied to the Western Allies by the Japanese occupation of Malaysia and other areas producing natural rubber in the Far East. As a substitute, butadiene-styrene synthetic rubber was urgently manufactured on a large scale, requiring the manufacture of styrene on a considerable scale. At the end of the war, with natural rubber freely available, the demand for synthetic rubber was reduced, and the styrene plants were sold cheaply to the chemical industry. Styrene is prepared by the Friedel—Crafts reaction between benzene and ethylene to yield ethylbenzene, which is dehydrogenated to the monomer. It is not an important chemical, except as a constituent of polymers, which are produced by mass, solution or suspension polymerization, usually the last; emulsion polymerization gives polystyrene latex. The quality of the polymer is monitored by softening point, solution viscosity of a 2% solution in toluene, and the proportion of methanol-soluble material. The softening point is particularly affected by residual monomer, as is odour and the acceptability for food contact applications.