Properties and morphology of polystyrene and linear low density polyethylene polyblend and polyalloy

A co‐rotating twin screw extruder was employed in melt mixing and reactive extrusion of polystyrene/linear low density polyethylene (PS/PE) blends. Blends of PS/PE in the ratio of 9: 1 were prepared under different conditions of shear mixing and with different concentrations of dicurnlyl peroxide (DP) and triallyl isocyanurate (TALC) coupling agent. The Charpy impact strength of unnotched samples of melt blends was found to be lower than that of the polystyrene and was not affected much by the different conditions of melt mixing at different rates of extrusion, screw speeds, and screw configurations. In the case of reaction‐extruded blends, the impact strength initially deteriorated with small addition of TAIC/DP, but improved with further increase in the level of TAIC/DP, exceeding that of polystyrene at an optimum concentration. With even further increase in TAIC/DP concentration, the impact strength again decreased. This was attributed to the different extents of coupling reactions of PE‐TAIC‐PE, PE‐TAIC‐PS, and PS‐TAIC‐PS with different levels of TAIC/DP. The interfacial adhesion of the incompatible PS‐PE was postulated to be improved by the graft copolymers formed during reactive extrusion. This observation was supported by melt rheology, thermal characterization, molecular weight, and fracture surface morphology studies.