writer：Jian Kang, Jingping Li, Shaohua Chen, Hongmei Peng, Bin Wang, Ya Cao, Huilin Li, Jinyao Chen, Jingga
keywords：Z-N catalysts
source：期刊
specific source：Journal of Applied Polymer Science 2013, DOI:10.1002/app.38984.
Issue time：2013年
Detailed characterization of the crystallization behavior is important for obtaining better structure property correlations of the isotactic polypropylene (iPP), however, attributed to the complexity in ZN-iPP polymerization, the relationship between crys- tallization behavior and the stereo-defect distribution of iPP is still under debate. In this study, the crystallization kinetics of the pri- mary nucleation, crystal growth and overall crystallization of two iPP samples (PP-A and PP-B) with nearly same average isotacticity but different stereo-defect distribution (the stereo-defect distribution of PP-B is more uniform than PP-A) were investigated. The results of isothermal crystallization kinetics showed that the overall crystallization rate of PP-A was much higher than that of PP-B; but the analysis of self-nucleation isothermal crystallization kinetics and the polarized optical microscopy (POM) observation indi- cated that the high overall crystallization rate of PP-A was attributed to the high primary nucleation rate of the resin. The stereo- defect distribution plays an important role in determining both the nucleation kinetics and crystal grow kinetics, and thus influence the overall crystallization kinetics. A more uniform distribution of stereo-defects restrains the crystallization rate of iPP, moreover, it has more influence on nucleation kinetics, comparing with the crystal growth.