کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5188068 | 1381144 | 2008 | 6 صفحه PDF | دانلود رایگان |
Syndiotactic polypropylene (sPP) fiber was prepared by melt spinning with the taken-up velocity of 200-700Â m/min, the conformation and crystallization of which were systematically investigated by a combination of Fourier transform infrared (FTIR) spectroscopy, wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). The results indicated that sPP fibers consist of form I crystal with helical conformation at the spinning velocity of 200-300Â m/min, and the crystallinity and orientation are improved with the increase of spinning velocity in this range. As the spinning velocity exceeds 300Â m/min, sPP fibers contain mainly mesophase with trans-planar conformation and the content of form I decreases correspondingly. The crystallization behavior of sPP fiber with spinning velocity is different from that of most other crystalline polymers, i.e., the theory of orientation-induced crystallization is not well conformed to. For sPP, form I comprising of helical conformation is thermodynamically stable, though extensional stress can lead to transition from helical to trans-planar conformation, which is not favorable for the crystallization of form I.
Journal: Polymer - Volume 49, Issue 5, 3 March 2008, Pages 1350-1355