Molecular Structure of Isotactic Polypropylene Formed from Homogeneous Solution. Gelation and Crystallization

被引:0
|
作者
Takahiko Nakaoki
Yoritsugu Inaji
机构
[1] Ryukoku University,Faculty of Science and Technology
来源
Polymer Journal | 2002年 / 34卷
关键词
Isotactic Polypropylene; Gelation; Crystallization; Morphology; Thermal Analysis; Solid-State ; C Nuclear Magnetic Resonance (NMR);
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中图分类号
学科分类号
摘要
The molecular structure and morphology grown from isotactic polypropylene (iPP)/o-dichlorobenzene solution were investigated by thermal analysis and high-resolution solid-state 13C NMR. The morphology varied depending on incubated temperature. A gelation occurred below 70°C, while the crystallization took place over 80°C. The crystal obtained was identified with the α-form, which is the most stable crystalline modification of iPP. In CP/MAS 13C NMR spectrum, the chemical shift of methylene, methine, and methyl carbons provided almost the same shift for both the gel and α-form, but the characteristic doublet for methylene and methyl signals of the gel was different in intensity ratio with the α-form. These results indicate that the gel-forming crystal is identified with α1-form, being the disordered α-form. Indeed, the lower melting temperature and smaller melting enthalpy than the crystal were observed by thermal analysis. This result connects to the incompleteness of crystal formed in the gel.
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页码:539 / 543
页数:4
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