Fine structure and physical properties of poly(ethylene terephthalate)/polyethylene bicomponent fibers in high-speed spinning. II. Poly(ethylene terephthalate) sheath/polyethylene core fibers

Abstract

The high-speed melt spinning of sheath/core type bicomponent fibers was performed and the change of fiber structure with increasing take-up velocity was investigated in comparison with the results of our previous study. Two kinds of polyethylene, high density and linear low density (HDPE, LLDPE) with melt flow rates (MFR) of 11 and 50 [HDPE(11), LLDPE(50)], and poly(ethylene terephthalate) (PET) were selected and two sets of sheath/core combinations [PET/HDPE(11) and PET/LLDPE(50) bicomponent fibers] were studied. The structure of each component in high-speed spun bicomponent fibers was analyzed through the birefringence, wide-angle X-ray scattering pattern, differential scanning calorimetry thermogram measurements, tensile tests, and so forth. In the PET/PE bicomponent fiber the structural formation of the PET component was promoted but that of the PE component was suppressed as compared to those of single-component fibers. Neither HDPE nor LLDPE affected the fine structure formation of the bicomponent fiber. Because the thermal properties of PE and PET are quite different from each other, the interfacial instability of the PET/PE bicomponent fiber was found to be serious compared to that of the PE/PET bicomponent fiber. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2267–2277, 2000