Melting and crystallization behaviors, morphology, and mechanical properties of -polypropylene/polypropylene-graft-maleic anhydride/calcium sulfate whisker composites

The melting and crystallization behaviors, morphology, and mechanical properties of polypropylene (PP)/surface-treated calcium sulfate (CaSO4) whisker (T-CSW), -PP/T-CSW, and -PP/polypropylene-graft-maleic anhydride (PP-g-MAH)/T-CSW composites had been investigated via differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), polarized light microscopy (PLM), scanning electron microscopy (SEM), and mechanical tests. We found that T-CSW was an -nucleating agent and increased the crystallization temperatures of PP, but PP-g-MAH and high loadings of T-CSW had weakly negative effects on the crystallization rates of PP. The T-CSW restrained the formation of -spherulites, and the spherulitic size decreased in the composites. PP-g-MAH improved the compatibility and adhesion between T-CSW and the matrix. The notched impact strength was improved, and the tensile strength was enhanced at low levels of T-CSW, while the flexural modulus was weakened for -PP/T-CSW and -PP/PP-g-MAH/T-CSW composites versus PP/T-CSW composites. POLYM. COMPOS., 37:2121-2132, 2016. (c) 2015 Society of Plastics Engineers