Dynamic mechanical characterization of gel phase in high impact polystyrene

The mechanical properties of the reinforcing phase of rubber modified polymers are important in determining the performance of the composite material. Of particular interest are the modulus values of the rubber particle phase. Stress concentrations in the rigid phase are determined by the shear modulus of the rubber particles; therefore, the knowledge of these values would be helpful in studying the crazing phenomenon in rubber modified polymers. For this reason the gel phase of a rubber modified polystyrene was separated by high speed centrifugation and shear modulus determinations made by means of a torsion pendulum over a wide temperature range.