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Investigation on the dynamic crystallization and melting behavior of β ‐nucleated isotactic polypropylene with different stereo‐defect distribution—the role of dual‐selective β ‐nucleation agent
Author(s) -
Kang Jian,
Wang Bin,
Peng Hongmei,
Li Jingping,
Chen Jinyao,
Gai Jinggang,
Cao Ya,
Li Huilin,
Yang Feng,
Xiang Ming
Publication year - 2014
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/pat.3210
Subject(s) - crystallization , tacticity , differential scanning calorimetry , nucleation , materials science , chemical engineering , crystallography , composite material , polymer , thermodynamics , chemistry , organic chemistry , polymerization , physics , engineering
The selectivities of different β ‐nucleating agents might be quite different from each other, which is important in determining the crystallization and properties of the obtained β ‐isotactic polypropylene ( β ‐iPP). However, the relationship between molecular structure and dynamic crystallization behavior of β ‐iPP nucleated by dual‐selective β ‐nucleating agent (DS‐ β ‐NA) is still not clear. In this study, the dynamic crystallization and melting behavior of two β ‐iPP with nearly same average isotacticity but different stereo‐defect distribution, nucleated by a DS‐ β ‐NA ( N , N ′‐dicyclohexyl‐2,6‐naphthalenedicarboxamide; trade name TMB‐5), were studied by differential scanning calorimetry, wide‐angle X‐ray diffraction, and scanning electronic microscopy. The results indicated that in the presence of TMB‐5, the dynamic crystallization and melting behavior of the samples are quite different because the joint effects of the dual selectivity of TMB‐5 and stereo‐defect distribution of the iPP under different cooling rates. Two important roles were observed: (i) slow cooling rate favors the formation of high β ‐fraction; and (ii) high crystallization temperature favors the crystallization of α ‐phase accelerated by TMB‐5. Generally, the dual selectivity of the DS‐ β ‐NA, the stereo‐defect distribution of iPP, and the cooling rate were important factors in determining the formation of β ‐crystal. Copyright © 2013 John Wiley & Sons, Ltd.