Structure and properties of melt-spun high acrylonitrile copolymer fibers via continuous zone-drawing and zone-annealing processes

Continuous zone-drawing and zone-annealing processes have been utilized to probe improvements in mechanical performance of melt-spun high acrylonitrile copolymer fibers (AMLON™). The as-spun fibers were zone-drawn at different ratios in a narrow temperature range of 100–105 °C and then zone-annealed. As a result of these processes, the fibers show substantial increases in tensile strength and tensile modulus (about three times) and significant improvements in elongation-at-break (about two times) after zone annealing. The thermal transition behavior, dimensional stability and dynamic relaxation properties of the as-spun, zone-drawn and zone-annealed fibers have been studied using differential scanning calorimetry, thermal mechanical and dynamic mechanical experiments. Their mechanical and thermal property changes after the zone-drawing and zone-annealing processes can be associated with the microscopic structural evolution including crystallinity, crystal orientation and apparent crystallite size detected by wide angle X-ray diffraction experiments.