Improved toughened polystyrene and a process for the preparation thereof

摘要

Toughened polystyrene is made by polymerizing a solution comprising styrene and a copolymer of at least 99.5% by weight butadiene and 0.0001 to 0.5% by weight of butadiene, the product containing 1 to 30% by weight of the butadiene copolymer. The butadiene copolymer used is preferably one containing a high proportion of 1,4-linkages. The polymerization may be accelerated by means of catalysts such as dicumyl, lauroyl and di-tert.butyl peroxides, tert.butyl perbenzoate and azobisisobutyronitrile. The polymerization is preferably carried out in bulk by a two-stage process which involves stirring the mixture in a first stage and completing the reaction without stirring in a second stage. Alternatively, the reaction may be carried out in aqueous dispersion as described in Specification 986,171.