纳米ZnO对等规聚丙烯结晶的异相成核作用

Heterogeneous Nucleation Effect of Nano-ZnO on Isotactic Polypropylene Crystallization

采用熔融共混法制备了nano-ZnO/等规聚丙烯(iPP)复合材料,研究了振荡剪切条件下nano-ZnO对iPP结晶的异相成核作用,并与其静态结晶行为作对比。结果表明:静态结晶下,当nano-ZnO质量分数大于5%时,nano-ZnO对iPP结晶有明显的异相成核作用,使iPP结晶温度大幅度提高,相容剂PP接枝马来酸酐(PP-g-MAH)的加入增强了nano-ZnO粒子与iPP基体的界面相互作用,改善了纳米粒子的分散性,促进了iPP基体的异相成核。振荡剪切作用下,降低结晶温度和加入nano-ZnO均能促进iPP成核,当nano-ZnO质量分数大于3%后,异相成核达到饱和,振荡剪切对nano-ZnO/iPP复合材料存在显著的诱导结晶作用;加入PP-g-MAH后,nano-ZnO分散性的改善及其与iPP基体界面相互作用的加强使得nano-ZnO/iPP复合材料的结晶诱导时间明显缩短。

A series of nano-ZnO/isotactic polypropylene(i PP)composites were prepared via melt blending.Heterogeneous nucleation effect of nano-ZnO on i PP under oscillation shear was investigated,which was compared with the phenomena under static crystallization.The results show that when the mass fraction of nano-ZnO is more than 5%,nano-ZnO has obvious heterogeneous nucleation effect on i PP matrix under static crystallization,with the cryatallization temperature of i PP shifting to higher temperature significantly.The compatibilizer maleic anhydride grafted PP(PP-g-MAH)enhances the interfacial interaction between nano-ZnO particles and i PP matrix,which improves the dispersion of nanoparticles,and promotes the heterogeneous nucleation of i PP matrix.Both decreasing the cryatallization temperature and adding nano-ZnO can promote the nucleation of i PP under oscillation shear.When the mass fraction of nano-ZnO is more than 3%,heterogeneous nucleation effect of nano-ZnO reaches saturation.Oscillatory shear can also significantly induce crystallization of nano-ZnO/i PP composites.The improvement of the dispersion of nano-ZnO and the strengthening of interfacial interaction between nano-ZnO and i PP matrix make the crystallization induction time of nano-ZnO/i PP composites shorten obviously after adding PP-g-MAH.