Investigation on β-polypropylene/PP-g-MAH/surface-treated calcium carbonate composites

beta-Polypropylene composites containing calcium carbonate treated by titanate coupling agent (T-CaCO3) and maleic anhydride grafted PP (PP-g-MAH) were prepared by melt compounding. The crystallization, morphology and mechanical properties of the composites were investigated by means of differential scanning calorimetry, wide-angle X-ray diffraction, polarized light microscopy, scanning electron microscopy and mechanical tests. It is found that both T-CaCO3 and NT-C are able to induce the formation of beta-phase, and NT-C greatly increases the beta content and decreases the spherulitic size of PP. PP-g-MAH facilitates the formation of beta-form PP and improves the compatibility between T-CaCO3 and PP. Izod notched impact strength of beta-PP/T-CaCO3 composite is higher than that of PP/T-CaCO3 composite, indicating the synergistic toughening effect of T-CaCO3 and beta-PP. Incorporation of PP-g-MAH into beta-PP/T-CaCO3 composite further increases the content of beta-crystal PP and improves the impact strength and tensile strength when T-CaCO3 concentration is below 5 wt%. The nonisothermal crystallization kinetics of beta-PP composites is well described by Jeziorny's and Mo's methods. It is found that NT-C and T-CaCO3 accelerate the crystallization rate of PP but the influence of PP-g-MAH on crystallization rate of beta-PP composite is marginal. POLYM. COMPOS., 2012. (C) 2012 Society of Plastics Engineers