Novel Method for Toughening of Polystyrene Based on Natural Rubber Latex

γ-Radiation vulcanized natural rubber latex/phase transfer/bulk polymerization is a novel process for the preparation of toughened polystyrene based on natural rubber latex. The negatively charged γ-radiation vulcanized natural rubber latex was first titrated with benzyldimethylhexadecylammonium chloride in the presence of a styrene monomer. At a critical transfer concentration, the crosslinked rubber particles transferred from the aqueous phase into the styrene phase in which they swelled, depending on the irradiation dose used. By bulk polymerization of the styrene phase containing transferred particles, the polymer blends exhibited two-phase morphology similar to that of commercial high-impact polystyrene that was microscopically obtained. The final product showed an increase in the unnotched Izod impact energy over the unmodified polystyrene. The effect of irradiation dose, rubber content, and initiator concentration on the impact property and morphology of toughened polystyrene prepared was investigated.