Rubber Modification of Syndiotactic Polystyrene

Polystyrene (PS) in its atactic and syndiotactic forms is a brittle thermoplastic, even in an orientated state [4]. To improve the toughness of aPS, impact modification has been practised for a long time, either by polymerizing the styrene in the presence of a polybutadiene rubber leading to high-impact polystyrene, commonly called HIPS, or by blending the polystyrene with multi-block copolymers, mainly of the styrene-butadiene-styrene (S-B-S) type. 

Modern Styrenic Polymers Polystyrene and Styrenic Copolymers. Edited by J. Scheirs and D. B. Priddy V 2003 John Wiley Sons Ltd 

In the case of sPS, the problem of its brittleness can be even more acute since it has to compete with engineering plastics which possess an inherent toughness superior to that of sPS. For this reason, a good impact modification of this product is of paramount importance and may even be essential for its survival as a commercial thermoplastic. For this reason a chapter of this book has been dedicated to the impact modification of sPS using elastomers. Since rubber modification plays such an important role for styrene polymers, whether atactic or sydiotactic, we will first look at the methods of energy dissipation in these homopolymers on impact. 

The use of glass fibres to enhance energy dissipation, which only functions if the fibres are oriented perpendicular to the crack propagation, is important for applications of sPS. However, since this chapter is concerned primarily with the rubber modification of sPS, it will not be considered in detail here. 

in either its atactic or syndiotactic form, is a polymer which shows no segmental mobility of chain segments below its glass transition temperature. Secondary relaxation processes which can be attributed to mobility in the main chain are missing. Therefore, these materials do not exhibit long-range energy 

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RUBBER MODIFICATION OF SYNDIOTACTIC POLYSTYRENE Table 19.1 Impact modification of sPS as described in EP 318 793 [15]... 

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