Mechanical, rheological, and thermal properties of calcium carbonate filled polypropylene / linear low density polyethylene composites

Abstract

The mechanical properties, melting temperature, glass transition temperature, crystallization temperature and rheological properties of polypropylene (PP) with varying weight percentage of linear low density polyethylene (LLDPE) at 10, 20, 30, and 40 wt % were studied. PP/LLDPE (60/40) was selected and investigated at different fraction of calcium carbonate (0-40%). The influence of CaC03 treated with 2% aminopropyltriethoxy coupling agent was also used to facilitate the link between filler and matrix. Tensile test, impact resistance, flexural test, viscosity, shear stress and shear rate of these blends were evaluated. Differential scanning calorimetry (DSC) was used to investigate the miscibility of PP/LLDPE blends and glass transition temperature was determined by dynamic mechanical analysis (DMA). The fractographic analysis of these blends was examined by scanning electron microscopy (SEM). Results indicated that the increase in LLDPE contents lead to decrease the tensile and flexural properties while the impact resistance of PP/LLDPE blends increase. However the increase in CaC03 amounts lead to increase both flexural strength and modulus. In the second part of this study, apparent viscosity of PP/LLDPE blends is affected by LLDPE contents due to lack of matrix reinforcement. On the other hand, incorporated of CaC03 into PP/LLDPE blends (60:40) has successfully increased the viscosity while CaC03 treated by aminopropyltriethoxy (AMPTES) coupling agent enhances the rheological properties. In the third part of this research, thermal properties were studied. Thermogravimetric analysis indicated that the total weight loss of PP/LLDPE/CaC03 composites decreases with increasing CaC03 loading. Heat deflection temperature of PP/LLDPE blends increases at all CaC03 loading.