Abstract: The polypropylene(PP)/nano-TiO2 composites were prepared via melt mixing. The dispersion of nano-TiO2, spherulitic morphology, and nonisothermal crystallization behavior of PP were studied using transmission electron microscopy (TEM), polarized optical microscope (POM) ，differential scanning calorimetry (DSC), and wide angle X-ray diffraction (WAXD). Results showed that nano-TiO2 dispersed uniformly in the nanoscale in PP. The spherulites in PP/nano-TiO2 composite was smaller than that in neat PP. With increasing content of nano-TiO2 , the size of spherulites decreased firstly and then increased. When the content of nano-TiO2 was 2 %, the spherulites of PP/nano-TiO2 composite was the smallest. The addition of nano-TiO2 accelerated the crystallization rate of PP. Nano-TiO2 promoted the formation of β crystals , when the content of nano-TiO2 was 1 %, the content of β crystal in the composite reached 25.2 %.

Key words: polypropylene, nano-titanium dioxide, nonisothermal, composite, crystal morphology