Evaluation of the extent of the gel particle grafting of impact polystyrene

High Impact Polystyrene (HIPS) consists of a glassy polystyrene matrix and a rubber-like particle phase (gel phase). The extent of grafting of the gel phase is known to be an important parameter in the fracture toughness of the material. 1]. A simple quantitative model is developed in this paper to determine the extent of gel-particle grafting from the observed shifts in the glass transition temperature of the gel phase of three commercial types of HIPS.Although the increase in interfacial 2] and gel-particle grafting accounts for an increase in the energy absorbed before fracture at low strain rates, above a certain amount of grafting the material becomes embrittled at high strain rates. The adhesion factor A of mesophase models 3, 19], considered between the main phases of the material, was found to correlate with the observed impact behaviour.