Abstract
The changes in performance characteristics, such as tenacity and elastic recovery, of copolyether-ester fibers were compared for different post-heat treatments (with or without tension). The differences in the mechanical behaviour were linked to changes in the microstructure which are obtained from wide angle X-ray scattering (WAXS), small X-ray scattering (SAXS) and birefringence techniques. The obtained results showed that the performance of the fibers is strongly dependent on the heat-treatment conditions. The treatment with tension proved to be an effective and viable approach for comprehensively improving the performance characteristics of the fibers, such as tenacity, elasticity and stability. A clear distinction is observed for the treatment without tension, which increases the elasticity but lowers the tenacity of the fibers. Heat treatments without tension lead to small crystal formations and partial crystal fusion between some small crystalline regions within the fibers. The lower molecular orientation during this process leads to the loss of tenacity. When heat treated with tension, a small amount of amorphous hard segments began to crystallize under the tensile stress, resulting in larger phase separation, and part of the amorphous region became oriented, improving the tenacity and elastic recovery of the fibers.
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