Effect of Filler Treatment on Crystallization, Morphology and Mechanical Properties of Polypropylene/Calcium Carbonate Composites

Pimelic acid (PA) was used as a new surface modifier for CaCO3. The effects of PA treatment on the crystallization, morphology, and mechanical properties of PP/CaCO3 composites were investigated. Fourier transform infrared (FTIR) spectroscopy analysis revealed that PA bonded to CaCO3 and formed a calcium pimelate surface layer after reacting with CaCO3. The results of wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and polarized light microscopy (PLM) proved that the PA treated CaCO3 induced a large amount of -iPP and decreased the spherulitic size of PP. The results of scanning electron microscopy (SEM) showed that the PA treatment enhanced the interfacial adhesion between the filler and the matrix, indicating the improvement of the compatibility between PP and CaCO3. The toughness of the composites was improved by the more ductile -form spherulites. When 1% of PA treated CaCO3 was added, the notched impact strength reached its maximum, a value of 19.79 kJ/m2, which was 3.64 times greater than that of the pure PP.