Effect of Malonic Acid Treatment on Crystal Structure, Melting Behavior, Morphology, and Mechanical Properties of Isotactic Polypropylene/Nano-CaCO3 Composites

The influence of malonic acid (MA) treatment of nano-calcium carbonate (CaCO3) on the crystallization, morphology, and mechanical properties of isotactic polypropylene (iPP)/nano-CaCO3 composites have been studied. The results of differential scanning calorimetry (DSC), wide angle X-ray diffraction (W Lambda XD) and polarized light microscopy (PLM) show that untreated nano-CaCO3 facilitates the formation of alpha phase, while MA treated nano-CaCO3 increases the relative content of beta phase of iPP dramatically. The results of scanning electron microscopy (SEM) show that MA treated nano-CaCO3 has better dispersion in the matrix than the untreated one. The toughness of PP/MA treated nano-CaCO3 composite is improved drastically. When 2.5 wt% MA treated nano-CaCO3 is added, the Izod notched impact strength reaches its maximum, which is 2.89 times greater than that of the pure iPP.