Thermal Graft Copolymerization of Styrene with Rubber. III. Temperature Regime Influence of Styrene Copolymerization with Polybutadiene on High Impact Polystyrene Morphology

The dependence of the change of morphology of HIPS obtained by means of styrene copolymerization with rubber on the character of the temperature-time regime was investigated. The relative volume of the rubber phase was found to increase when the rubber concentration increased. However the falling of the specific volume of the rubber phase to 1% of rubber was being diminished. The specific volume of the rubber phase was lowered with increase of polymerization temperature as well. These changes are caused by homopolystyrene diffusion from the rubber phase to polystyrene as a result of polymer incompatability which is influenced by polymer molecular weight and medium viscosity. It was shown that one can change the rubber particle size also after prepolymerization up to high conversions of about 80–85% due to the stepped temperature-time regimes.