Evolutions of morphology and crystalline ordering upon annealing of quenched isotactic polypropylene |
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Authors: | Junchai Zhao Jie Qiu Yanhua Niu Zhigang Wang |
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Institution: | 1. CAS Key Laboratory of Engineering Plastics, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China;2. School of Materials Science and Engineering, Shijiazhuang Railway Institute, Shijiazhuang 050043, People's Republic of China;3. Graduate School, Chinese Academy of Sciences, Beijing 100049, People's Republic of China |
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Abstract: | Quenched mesomorphic isotactic polypropylene precursor material has been investigated as well as the material annealed at different temperatures. At room temperature, morphology and crystalline ordering of the materials have been studied by atomic force microscopy (AFM) and wide‐angle X‐ray diffraction (WAXD). The nodular morphology of the mesomorphic precursor remains constant for annealing temperatures Ta below 120 °C. Needle‐like or leaf‐like crystals form when Ta approaches the melting temperature of the precursor. WAXD data analyzed by peak‐fitting indicate that the crystalline ordering along both the chain axis and the lateral directions quickly develops during the mesomorphic‐to‐monoclinic transition, but slowly after the transition (Ta > 140 °C). Combining the AFM and WAXD results it is proposed that two decoupled structure evolution mechanisms are occurring. During the transition, only the crystalline ordering is increasing, but not the size of the nodules. After the transition, the geometry of the nodules changes considerably, whereas there is little additional increase of crystalline ordering. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1703–1712, 2009 |
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Keywords: | isotactic polypropylene morphology transitions |
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