Functionalization of polyethylenes and their use in reactive blending

Abstract

Abstract The grafting of maleic anhydride (MAn) to low density polyethylenes (PEs) dissolved in 1,2‐dichlorobenzene (DCB) has been studied. Grafting was successful at temperatures of about 160°C both in air without initiator and under nitrogen with the radical initiator 2,5‐di( t ‐butylperoxy)‐2,5‐dimethyl‐3‐hexyne (LPO). The presence of succinic anhydride grafts was shown by FTIR spectroscopy of the product; 1 H‐NMR spectroscopy indicates that the grafts consist of single succinic anhydride units. The graft content was determined by nonaqueous titration, and the extent of crosslinking inferred from the melt flow rates (MFR) of the products. The effects of concentration of initiator, MAn, and PE on the graft content were determined; the influence of PE structure, reaction time, and temperature was also studied. Melt blending of the grafted PE with polystyrene containing oxazoline functional groups (OPS) was investigated using a Rheomix mixer. The interpolymer reaction which occurs during blending was studied by means of FTIR, and the morphology of the blends by scanning electron microscopy (SEM). Information was also gained from the change in torque viscosity during the blending process.