熔融温度对β-iPP的结晶行为和晶体形貌的影响

Effect of the Melting Temperature on the Crystallization and Supermolecular Structure of β-iPP

通过差示扫描量热仪和偏光显微镜研究了稀土β成核剂-WBGⅡ对聚丙烯结晶行为和晶体形貌的影响,结果表明,短棒状成核剂WBGⅡ侧表面具有β成核剂作用,由于WBGⅡ的溶解性与成核能力相关,随着熔融温度(Tmelt)逐次升高,同一样品结晶形成的聚集态结构不同,Tmelt低于230℃时,形成的是针状晶体;Tmelt高于230℃形成花状晶体;随Tmelt不同,在230℃结晶峰的半高宽ΔW、结晶峰的初始斜率Si均发生突变,β晶型相对含量也明显提高。

WBGⅡis an efficient nucleating agent to prepare isotactic polypropylene（iPP） samples riching in β crystals.Depending on the melting tempreture（Tmelt）,WBGⅡ maybe partially or completely dissolve in the iPP melt.The structure and crystallization characteristics of the nucleated samples were studied by polarized light microscopy（PLM） and differential scanning calorimetry（DSC）.It was found that the lateral surface of the needle crystals acted as β-nucleating agent when Tmelt was lower than 230 ℃.When Tmelt was higher than 230 ℃,we observed dendritic and microcrystalline structures,and a spectacular ＂flower＂-like agglomerate.When Tmelt is different,iPP performs different crystallization behaviors.