| abstract |
High impact polystyrene having a predominant core-shell morphology is made by polymerizing styrene in the presence of polybutadiene using toluene as a solvent. The thermoplastic polymer composition is characterized by a continuous phase of polystyrene containing dispersed graft copolymer particles having a core-shell structure with a polystyrene core occluded inside a polybutadiene shell. The styrene is desirably batch polymerized using styrene/toluene mixtures of about 70:30 by weight in the presence of from about 9 to about 15 weight percent polybutadiene while flashing off the toluene solvent. |