表面接枝改性纳米二氧化硅填充聚丙烯的结晶行为

应用差示扫描量热方法研究了纳米二氧化硅 (SiO2 )及其表面接枝改性对聚丙烯 (PP)结晶过程、等温与非等温结晶动力学的影响 ,并研究了上述等温结晶的熔融行为和平衡熔点 .研究发现纳米SiO2 具有明显的异相成核效应 ,能够提高PP的结晶温度、熔融温度、结晶度和结晶速率 ,但降低聚丙烯结晶的完善程度 .粒子的表面接枝处理 ,因改善了粒子与基体的亲和性而有利于粒子成核效应的提高 ,而且此效应尚与粒子的分散相关

CRYSTALLIZATION PERFORMANCE OF ISOTACTIC POLYPROPYLENE FILLED WITH SURFACE GRAFTING MODIFIED NANO-SILICA

The influence of surface grafting modified nano-silica on the isothermal and non-isothermal crystallization kinetics of isotactic polypropylene (IPP) was investigated by DSC.The silica particles were pre-grafted with styrene,methyl methacrylate,ethyl acrylate and butyl acrylate,respectively.The experimental results show that the addition of nano-silica into PP has an obvious nucleating effect on the crystallization of PP,resulting in higher crystallization temperature and melting point,as well as higher crystallinity and the overall rate of crystallization,but lower crystalline regularity.The surface grafting treatment of the nanoparticles promotes the nucleating effect due to the increased miscibility between the particle and the matrix.The nucleating effect of the particles is also related with their dispersion state in the polymer matrix.The melting behavior of neat PP is different to that of the PP filled with nano-silica.The later has a more uniform crystal structure because the fillers act as nucleates.However,a faster isothermal crystallization process of the PP filled with nano-silica results in a lower equilibrium melting point,implying that the crystalline structure is less perfect in this case.