GMA/苯乙烯多组分单体接枝聚丙烯结晶行为研究

使用差示扫描量热计 (DSC)研究了甲基丙烯酸缩水甘油酯 苯乙烯 (GMA St)多单体熔融接枝聚丙烯[PP g (GMA co St) ]的等温和非等温结晶行为 ,用偏光显微镜观察了结晶的形态 ,并利用Avrami方程对其结晶动力学进行了分析 .研究发现接枝聚丙烯的结晶模式与PP相似 ,属于异相成核控制的球晶三维生长 ;但接枝聚丙烯的结晶温度 (Tc)显著提高 ,幅度高达 16～ 19℃ ,总结晶速率与纯PP相比明显加快 .接枝聚丙烯上GMA co St支链的存在 ,降低了成核界面自由能 ,促进了聚丙烯结晶的异相成核 .在接枝率不太高的情况下 ,随着接枝率的提高 ,接枝聚丙烯的结晶温度升高 ,总结晶速率加快 .在高接枝率范围内 ,随着接枝率的提高 ,接枝PP的Tc 不再升高 ,且由于接枝链的增长严重阻碍了球晶生长 ,导致接枝PP的总结晶速率反而随接枝率的升高而下降

CRYSTALLIZATION BEHAVIOR OF GMA/St MULTIMONOMER GRAFTEDPOLYPROPYLENE

The isothermal and nonisothermal crystallizations of glycidyl methacrylate/styrene(GMA/St) multimonomer melt|grafted polypropylene [PP| g |(GMA| co |St)] were investigated by DSC,crystals of the grafted PP were observed through polarized optical microscope.Avrami equation was used to analyze the kinetics of crystallization.The crystallization of the grafted PP was heterogeneous nucleated,and three dimensional growth of spherulites can be observed as in the case of neat PP.Compared to neat PP,the crystallization temperature( T -c) of the grafted PP increased 16～19℃ and the overall crystallization rate was accelerated dramatically.The grafts of GMA| co |St reduced the interfacial free energy of the surfaces of the crystal nuclei and promoted the heterogeneous nucleating.When the degree of grafting was not very high, T -c and overall crystallization rate of the grafted PP increased with increasing the degree of grafting.In the range of higher degree of grafting,with increasing the degree of grafting, T -c stopped rising and the overall crystallization rate was slowed down due to the severe obstruction of the grafts to the growth of the crystal.