Polystyrene modified by grafting

Several grades of modified polystyrene were obtained through the graft polymerization of styrene in the presence of modifiers such as ethylene-vinyl acetate (EVA), low density polyethylene (PE), and polybutadiene (PB). These modifiers were used by themselves and in combination. In all cases, the modifier concentration was kept constant at 8% w/w, and the product properties were determined as a function of composition. The polymerization technique employed was that of mass/suspension. The best results were obtained for the PS/mixed modifiers systems. The results confirm that graft copolymers present better impact properties than those of mechanical blends of similar composition.