Shear-induced pre-crystallization structures of long chain branched polypropylene under steady shear flow near the melting temperature |
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| Authors: | Shinichi Kitade Kazuo Asuka Isamu Akiba Yusuke Sanada Kazuo Sakurai Hiroyasu Masunaga |
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| Affiliation: | 1. Polyolefin Science & Technology Center, Japan Polychem Corporation, 1 Toho-cho, Yokkaichi, Mie 510-8530, Japan;2. Products Technical Center Two, Japan Polypropylene Corporation, 1 Toho-cho, Yokkaichi, Mie 510-8530, Japan;3. Department of Chemistry and Biochemistry, University of Kitakyushu, Fukuoka 808-0132, Japan;4. Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), 1-1-1 Kouto, Sayo 679-5198, Japan |
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| Abstract: | Shear-induced crystallization of a long chain hyper-branched polypropylene (LCB-PP, denoted PP-3) was carried out at a relatively high temperature of 170 °C, close to its melting temperature of 158 °C. Small-angle X-ray scattering (SAXS) showed that the intensity ratio of the normal to the perpendicular to the shear (V/H) was always larger than 1 for PP-3, indicating that shish-like structures were predominately formed and further growth to kebab was suppressed in PP-3. The crystallization behavior of PP-3 can be explained by the nature of PP-3 that there were a large amount of crystallization nuclei due to their branching points, and the point-like precursors formed from these nuclei were arrayed linearly along the shear direction and transformed into thread-like precursors or premature shishs; however, owing to the large amount of branching, further progress in crystallization was suppressed. |
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