On-line WAXD / SAXS Measurements of Fiber Structure Development in the CO_2 Laser-Hated-Drawing of Poly(ethylene terephthalate) Fiber

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The structures and properties of synthetic fibers are mainly determined during the secondary drawing process of fibers, so-called neck-like deformation. To observe the fiber structure development in-situ X-ray measurement system with the laser drawing process were designed and constructed. The neck drawing point on running fiber was successfully fixed by local irradiation of CO_2 laser using this new system. The positional fluctuation of neck-drawing point was less than 0.5mm, which was corresponding to the time resolution of several hundred micro seconds. In-situ measurements of fiber structure formation of poly(ethylene terephthalate) (PET) were performed at SPring8, where the strongest X-ray beam was available for scattering experiments in Japan. Wide angle X-ray Diffraction (WAXD) and Small angle X-ray Scattering (SAXS) were measured as a function of elapsed time after necking. Their dependence on the drawing ration also examined. Four-point SAXS patterns considering relative to lo … More ng period appeared from the necking point. Meanwhile crystal reflections in the WAXD pattern appeared after the four-point pattern. The density fluctuation in large scale came out earlier than crystallization. The meridional reflection (001') of around 5.4^<o__-> and the equatorial ones from PET crystal shows the different behavior in time evolution. The (001') diffraction peak appeared just after necking point. However the crystal diffractions came out at several milliseconds after necking. The peak of (001') grew up with the elapsed time at the initial stage and disappeared when the crystal diffraction peaks became clear. The (001') reflection originated with the conformation of the extended single chain of PET. Accordingly at the initial stage of fiber structure formation PET molecules were extended and constructed the two-dimensionally ordered structure. At the next step this structure transformed to crystal one. The further data analysis leaded to the new model of fiber structure development. Less