Abstract
The structural development of poly(butylene terephthalate) (PBT) fibers was analyzed using in situ wide angle X-ray diffraction and fiber temperature measurements during CO2 laser-heated drawing, in which the necking position on the running fiber could be fixed by CO2 laser irradiation. The measured parameters were determined as functions of the elapsed time after necking with a time resolution of 0.3 ms. The as-spun PBT fibers, which exhibited a low-oriented α-crystalline structure, were drawn to a draw ratio of 5 using laser heating. The (001′) reflection, which indicates a quasi-smectic fibrillar structure, was not observed before crystallization in contrast to measurements of poly(ethylene terephthalate) (PET) and poly(ethylene 2,6-naphthalene dicarboxylate) (PEN). The α-crystal was transformed into an oriented β-form crystal at the necking position, and the developed β-crystallites exhibited increased size and altered orientation <2 ms after necking. The fiber temperature increased rapidly at around Tg, and the rearrangement of the β-crystal primarily occurred as the fiber’s temperature rose from 100 to 160 °C. The oriented β-crystal of the drawn fiber transformed into the oriented α-crystal when the drawing tension was released.
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Acknowledgements
The synchrotron radiation experiments were performed at the BL40B2 SPring-8 facility with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (proposal no. 2008B1264). This research was supported by grant-in-aid no. 18550191 from the Japan Society for the Promotion of Science.
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Kim, KH., Kang, YA., Yokoyama, A. et al. In situ study of fiber structure development of poly(butylene terephthalate) in a continuous laser-heated drawing process. Polym J 44, 1030–1035 (2012). https://doi.org/10.1038/pj.2012.65
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DOI: https://doi.org/10.1038/pj.2012.65
