Effect of molecular weight and compatibilizer on miscibility and properties of LLDPE/NR blends

Abstract

The effect of molecular weight (entropic mixing) and compatibilizer (enthalpic mixing) on linear low-density polyethylene (LLDPE) and natural rubber (NR) blends were studied. Maleic anhydride (MA) was added to the LLDPE/NR blends at different concentrations to form in situ compatibilizer. The techniques used to determine compatibility were scanning electron microscopy (SEM), differential scanning calorimetry (DSC). The addition of MA to the blends improved the dispersity of the LLDPE/NR blends. A single glass transition temperature (To) was obtained for blends with certain amount of MA indicating miscibility of two polymers. Tm and Tc were found to be rather independent of the blend composition and the Mw of NR, but the degree of crystallinity decreased with amount of NR. The blends exhibited enhanced tensile properties with the addition of MA, which was attributed to better adhesion between two phases and the reduction in dispersed particle size. Higher amounts of MA or higher Mw of NR caused reduction in melt flow index (MFI) but improved mechanical properties. The effects of Mw and compatibilizer are compared.