Structure evolution of melt-spun poly(vinyl alcohol) fibers during hot-drawing

The drawability of melt-spun poly(vinyl alcohol) (PVA) fibers and its structure evolution during hot-drawing process were studied by differential scanning calorimetry (DSC), two dimensional X-ray diffraction (2-D WAXD) and dynamic mechanical analysis (DMA). The results showed that the water content of PVA fibers should be controlled before hot-drawing and the proper drying condition was drying at 200 degrees C for 3 min. PVA fibers with excellent mechanical properties could be obtained by drawing at 200 degrees C and 100 mm/min. The melt point and crystallinity of PVA fibers increased with the draw ratio increasing. The 2-D WAXD patterns of PVA fibers changed from circular scattering pattern to sharp diffraction point, confirming the change of PVA fibers from random orientation to high degree orientation. Accordingly, the tensile strength of PVA fibers enhanced by hot-drawing, reaching 1.85 GPa when the draw ratio was 16. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012