相对分子质量对聚丙烯结晶和熔融行为的影响

在中试装置上合成了一系列相对分子质量不同但相对分子质量分布相似的均聚聚丙烯。利用GPC,MFR,SAXS,DSC等方法考察了相对分子质量对聚丙烯晶体结构、结晶和熔融行为的影响。表征结果显示,相对分子质量越大,聚丙烯注塑样条的片晶越容易沿剪切方向取向,且其片晶厚度和非晶层厚度也越大。随着相对分子质量下降,聚丙烯的结晶温度和熔融温度降低,而结晶度增大。等规聚丙烯的平衡熔点为188.2℃。

Effect of relative molecular weight on crystallization and melting behavior of polypropylene

A series of homopolypropylenes with different relative molecular weight but similar relative molecular weight distributions were synthesized on the pilot plant. The in uences of relative molecular weight on the crystal structure,crystallization and melting behavior of polypropylene were investigated by GPC,MFR,SAXS and DSC. The characterization results show that the larger the relative molecular weight is,the easier the lamellae of the polypropylene injection molded sample is oriented in the shear direction,and the larger the lamella thickness and the amorphous layer thickness is. As the relative molecular weight decreases,the crystallization temperature and melting temperature of the polypropylene decrease,and the crystallinity increases. The isotactic polypropylene has an equilibrium melting point of 188.2 ℃.