Investigation on dry spinning process of ultrahigh molecular weight polyethylene/decalin solution

The relationship between the draw-down ratio in the dry spinning process of ultrahigh molecular weight polyethylene/decalin solution and the fiber performance through maximized after-drawing was investigated. The structural development during the after-drawing process was analyzed by scanning electron microscopy, differential scanning calorimetry, wide-angle X-ray diffraction, sonic velocity, and FTIR measurements. An optimum draw-down ratio was found in the multihole dry spinning process, which may be explained by molecular disentanglement and the composite effect of entropy and the viscosity component. The as-spun fiber by draw-down had an obvious shish kebab morphology, lower crystallinity, and a higher melting temperature compared with a free extrusion sample, and higher crystallinity and melting temperature compared with the fiber by first-stage after-drawing. During the subsequent after-drawing process, the crystallinity, melting temperature, X-ray diffraction, and sonic velocity orientation factors increased slowly in the higher after-drawing ratio region, which was not consistent with the rising tendency of the tensile properties. The polarized and unpolarized IR spectra reflected the variations of the orientation and the content of the folded chains. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 474–483, 2005