PP/纳米TiO_2复合材料的晶体形貌和非等温结晶行为

Nonisothermal Crystallization Behaviors and Crystal Morphology of PP/Nano-TiO_2 Composites

用熔融共混法制备了聚丙烯(PP)/纳米TiO2复合材料,用透射电子显微镜、偏光显微镜、差示扫描量热仪和广角X射线衍射仪对其纳米粒子分散性、晶体形貌和非等温结晶行为进行了研究。结果表明,纳米TiO2以纳米级尺寸均匀分散于PP基体中;130℃冷却和室温冷却时,PP/纳米TiO2复合材料的晶粒比纯PP的细,并且随着纳米TiO2含量的增加,其晶粒尺寸先减小后增大,纳米TiO2含量为2份时晶粒最细;纳米TiO2对PP结晶具有加速作用;复合材料的结晶活化能高于纯PP,并且纳米TiO2含量多且均匀时结晶活化能高;纳米TiO2含量较少时可诱导较多的β晶生成,当纳米TiO2含量为1份时,复合材料中β晶含量达到25.2%。

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 %.