Microsecond Analysis of Quasi-Smectic Fibrillar Structure in the Continuous Fiber Drawing of Poly(ethylene terephthalate)

Abstract

Structure devpelopment in the continuous laser-drawing process of poly(ethylene terephthalate) fibers was investigated with a time resolution of 0.2 ms by real time synchrotron X-ray diffraction and fiber temperature measurements. The (001′) and (003′) reflections of a quasi-smectic fibrillar structure were observed from 0.16 ms after necking, and the reflection intensity reached a maximum at around 0.3 ms after necking, when the elastic energy stored at the necking had been released. The d-spacing of the (001′) reflection decreased with increasing time, and the quasi-smectic fibrillar structure had a length of 70 nm and a radius of 7.0 nm. The crystallization induction time and crystallization rate were 0.3 ms and 1100 s–1 based on the fiber temperature profile and 0.6 ms and 1400 s–1 based on the equatorial reflection intensity profiles. In the azimuthal intensity profile under the 2θ/θ arrangement, a single meridional peak of the (003′) plane was observed, and it is considered that the quasi-smectic fibrillar structure oriented uniaxially along the fiber axis with an orientation factor of 0.986.

In situ study of fiber structure development of poly(butylene terephthalate) in a continuous laser-heated drawing process

“…The details of the in situ measurements described here can be found in our previous papers. [8][9][10][11][12][13][14] The running fiber was heated using a CO 2 laser beam generated by a PIN-20S laser source (manufactured by Onizuka Co. Ltd, Ome, Japan). The fiber was irradiated from three directions to minimize its cross-sectional temperature variation.…”

“…X-ray diffraction data and the fiber temperature were measured as functions of elapsed time t, which was calculated from the distance X between the measurement and necking points divided by the fiber running speed v. The distance X was controlled by shifting the necking position using a traveling mirror unit, as described in the previous reports. [8][9][10][11][12][13][14] …”

“…Additional details of the in situ WAXD measurement can be found in our previous reports. [8][9][10][11][12][13][14] The position y 0 and the half width s were determined by fitting the measurements to a Gaussian function (2). The effect of beam divergence on s was corrected using the width of the lead dioxide intensity profiles.…”

“…The in situ fiber temperature measurement was conducted in the same manner as in the previous studies. [8][9][10][11][12][13][14] RESULTS AND DISCUSSION Fiber temperature To determine the change in fiber temperature during the laser-heated drawing, the fiber temperature profile as a function of distance from the necking point was obtained and is presented in Figure 2. The origin of the horizontal axis in Figure 2 designates the necking point, Figure 1 Schematic diagram of the in situ measurement system.…”

“…[8][9][10][11][12][13][14] The measured parameters were determined as functions of the elapsed time, which was calculated using the distance between the measurement point and the necking position. This calculation allows good time resolution because the necking is confined to a narrow region in which CO 2 laser radiation produces rapid and uniform heating.…”