Maleic Anhydride-Grafted Linear Low-Density Polyethylene With Low Gel Content

Maleic-anhydride-grafted linear low-density polyethylene (LLDPE-g-MAH) with low gel content was synthesized by the solid-phase grafting polymerization of low molecular weight linear low-density polyethylene (LLDPE) with melt flow index of 49.4 g/10 min, its structure and properties were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, wide-angle X-ray diffraction, polarized optical microscopy, and capillary rheometer. At the experimental conditions, maleic anhydride is successfully grafted onto LLDPE with the grafting degree of 1.1-2.4% and the gel content less than 3.7% since the chain-branching reaction is dominant side reaction. The melting temperature of LLDPE-g-MAH is higher than that of pristine LLDPE due to the increased molecular polarity, but its degree of crystallinity and crystallization rate decrease due to its chain-branching structure. The apparent viscosity of LLDPE-g-MAH is higher than that of pristine LLDPE, and its shear-sensitivity is weakened due to the chain branching and subsequent difficulty in disentanglement under shear force. POLYM. ENG. SCI., 49:873-879, 2009. (c) 2009 Society of Plastics Engineers