Relaxation of shish‐kebab precursor in isotactic polystyrene after short‐term shear flow |
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Authors: | Yunfeng Zhao Go Matsuba Koji Nishida Tetsuaki Fujiwara Rintaro Inoue Inga Polec Cong Deng Toshiji Kanaya |
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Affiliation: | 1. Institute for Chemical Research, Kyoto University, Uji, Kyoto‐fu 611‐0011, Japan;2. Department of Engineering, Yamagata University, 4‐3‐16 Jonan, Yonezawa, Yamagata 992‐8510, Japan |
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Abstract: | We studied the formation and relaxation of precursors of shish‐kebab in isotactic polystyrene after applying pulse shear flow at temperatures above the nominal melting temperatures Tm (=223 °C). It was found that the string‐like objects that were assigned to precursors in a previous article appeared in micrometer scale up to ~285 °C, which was very close to the equilibrium melting temperature T (=289 °C), and the length and the diameter showed two‐step decays consisting of the fast and slow (almost nondecaying) components below ~270 °C, whereas the slow component disappeared above ~270 °C, suggesting that some mechanism stabilizing the string‐like objects disappeared at ~270 °C. It was also found that the two‐step decay was a nature of a single string‐like object, but not an average nature of many precursors, showing heterogeneous inner structure of the precursor. We discussed a possibility that the string‐like object had a fringed micelle type structure including large crystals with a melting temperature of ~270 °C. Within the proposed picture, the highest temperature for the precursor formation (~285 °C) was explained as a melting of the large crystals in oriented melt. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010 |
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Keywords: | crystallization isotactic isotactic polystyrene polystyrene precursor relaxation shear shear flow shish‐kebab |
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