Orientation prior to crystallisation during drawing of poly(ethylene terephthalate)

Online wide‐angle X‐ray diffraction/small‐angle X‐ray scattering measurements for the CO2‐laser‐heated drawing of poly(ethylene terephthalate) fiber

“…This indicates that only a part of amorphous phase is highly oriented. This scattering should be the same as that observed for PET film by Mahendrasingam et al 20,[22][23][24] and Kawakami et al 31,32 Crystal diffraction appeared abruptly 20 ms after necking. It is not observed at all in the 17 ms diffraction image, and becomes clear in the 30 ms image.…”

“…However, the crystallization time obtained in this study is far shorter than the crystallization time of 200 ms reported by Mahendrasingam. 23 The crystallization rate is almost 10 times that reported previously, probably due to the difference in drawing conditions; i.e., a drawing temperature about 100 K higher 37 , a draw ratio 0.8 higher, and a strain rate 100 times as large. Accordingly, application of the measuring system used in this study enables direct analysis of the fiber structure development mechanism of a high-temperature, high-strain-rate, high-draw-ratio, and high-stress neck-drawing process.…”

“…In addition, the fiber structure development process is not analyzed by the latter category of studies. The results reported by Mahendrasingam et al [21][22][23][24][25] are notable, because they reported x-ray diffraction images for the highest strain rate. They observed orientation-induced crystallization behavior by the images that were measured every 40 ms for a batch drawing process at strain rates of 0.01 to 15 s -1 , temperatures of 90 to 120°C, and draw ratios of 2.2 to 4.0.…”

“…This result agreed with the reports by Kolb et al 13 and Mahendrasingam. 23 that the crystallization occurred after the neck-like deformation. However, the crystallization time obtained in this study is far shorter than the crystallization time of 200 ms reported by Mahendrasingam.…”

“…For the drawing process, most on-line measurement studies fall into one of two categories; batch drawing under small strain rate [20][21][22][23][24][25][26][27][28][29][30][31][32] , and draw ratio dependence of continuous drawing [33][34][35][36] . In both cases, x-ray diffraction images are taken at a fixed position.…”