Plastics Based on Styrene

It may well be argued that the history of polystyrene is more closely bound up with the history of the 20th century than is the case with any other plastics material. 

In 1930 BASF, then part of IG Farhen, installed a plant for producing 100 tonnes of polystyrene per annum and in 1933 the first injection moulded articles were produced. In the US semi-plant-scale work at the Dow Chemical Company showed promise of commercial success in 1934. As a consequence there became available shortly before World War II a material of particular interest because of its good electrical insulation characteristics hut otherwise considerably inferior to the polystyrene available today. Because of these excellent electrical characteristics prices were paid of the order of several dollars per pound for these polymers. 

In 1942 the Japanese overran Malaya and the then Dutch East Indies to cut off the main sources of natural rubber for the United States and the British Commonwealth. Because of this the US Government initiated a crash programme for the installation of plants for the manufacture of a rubber from butadiene and styrene. This product, then known as GR-S (Government Rubber-Styrene), provided at that time an inferior substitute for natural rubber but, with a renewed availability of natural rubber at the end of the war, the demand for GR-S slumped considerably. (Today the demand for SBR (as GR-S is now known) has increased with the great improvements in quality that have been made and SBR is today the principal synthetic rubber). 

After the war, however, there was a large surplus capacity of plant for the manufacture of styrene and polystyrene together with a great deal of knowledge and experience that had been collected over the war years. It was therefore found possible to produce polystyrene, not as an expensive electrical insulator, but as a cheap general purpose thermoplastic. 

Because of such desirable characteristics as low cost, good mouldability, excellent colour range, transparency, rigidity and low water absorption, polystyrene became rapidly developed. For many purposes, however, it was considered to be unacceptably brittle and this led to the development of the rubber-modified high-impact polystyrene (HIPS) and to the complex ABS, AMBS and 

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J.A. Brydson, "Plastics based on styrene," in Plastics Materials, chapter 16, pp. 425 65. Buttworth-Heinemann, Woburn, MA, 7th edition, 1999. 

PS is the simplest plastic based on styrene. Its structure is shown in Figure 2.51. 

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