| Abstract: | The internal structure and orientation behavior of two series of spandex fibers, which were made with different spinning methods and different soft and hard segment types, were studied by FTIR (Fourier Transform Infrared Spectroscopy), polarizing light microscopy, and Instron. The orientation behavior of hard and soft segments was studied with FTIR and those of polymeric chains with polarizing miscroscopy while the fibers were being stretched by the mechanical stretcher. The orientation behavior of dry-spun fibers was observed to be very different from that of the melt-spun fibers, which may be explained in terms of the internal structural difference such as the degree of phase separation and mechanical stability of the hard domains between the two types of fibers. In general, the dry-spun fibers showed better elastic recovery property than the melt-spun fibers. Since the polymer for the dry-spun fibers was synthesized with ethylene diamine as a chain extender resulting in the urea groups in the hard segments, it forms more stable hard domain due to the high cohesion energy between the urea groups. The change of the birefringence values during the cyclic deformation was studied with the polarizing light microscopy. The birefringence behaviors of the two dry-spun fibers were similar, whereas there was a noticeable difference between the two melt-spun fibers. The difference was explained in terms of the effect of crosslinking agent in one of the melt-spun fibers, which can stabilize the hard domain structure against the external stress. Mechanical hysteresis values measured gave results consistent with those of FTIR and birefringence measurements. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1821–1832, 1997 |
