用DSC方法研究β-定向结晶聚丙烯树脂的结晶动力学

Study of Crystallization Kinetics of β-Crystalline-Specified Polypropylene Resins by DSC

利用DSC方法分别研究了釜内聚合制备的β-定向结晶聚丙烯(PP)树脂的等温结晶和非等温结晶动力学,并与普通PP树脂进行了对比。结晶动力学实验结果表明,β-定向结晶PP树脂中所分散的成核剂组分促进了PP结晶时的异相成核,显著提高了PP树脂的结晶速率,在相同的结晶温度或相同的降温速率下,其半结晶时间均较普通PP树脂明显缩短;高度分散的成核剂组分阻碍了PP分子链在结晶过程中从熔体到晶体表面的运动,因而β-定向结晶PP树脂的非等温结晶活化能高于普通PP树脂。说明釜内聚合方法能直接实现成核剂组分在PP树脂基体中的均匀分散。

The isothermal and the non-isothermal crystallization kinetics of β-crystalline-specified polypropylene （PP） resins produced by in-situ polymerization were investigated by means of DSC, and the results were compared with the crystallization kinetics of ordinary PP. It was revealed that the β-nucleating agent dispersed in the β-crystalline-specified pp accelerated the heterogeneous nucleation during crystallization so that its crystallization half-time, compared with that of the ordinary PP, was obviously shortened either at the same crystallization temperature or at the same cooling rate. The non-isothermal crystallization activation energy of the β-crystalline-specified PP was higher than that of the ordinary PP due to the hindering effect imposed by the nucleating agent which weakened the transfer of PP segments from the PP melt to the crystal surface. The homogeneous dispersion of the β-nucleating agent can be realized by the in-situ ororwlene nolvmerizatinn