Relationship Between Structure, Properties And Processing Technology Of Copolyester-ether Fiber

As thermoplastic elastic fiber, copolyether-ester(PEE) fibers have numerous advantages. However, compared with commercial products of polyurethane elastic fibers, the lower elastic recovery limited the development of PEE fibers. As we all know, the elastic properties of fibers depend on their morphological and structure. The chemical composition, spinning technology and heat-treatment have important effect on the morphology structure of PEE fibers. In this article, the effect of the ratio of hard(PBT) and soft segments(PTMG), spinning speed and heat-treatment on the elastic recovery and morphology structure of PEE fibers were investigated.The thermoplastic poly(ether ester) fibers with various hard segment contents were prepared by melt spinning. The morphology structure of fibers with different scales was studied by birefringence, SAXS and WAXS. Combined with the mechanical properties and shrinkage in boiling water, it turned out that the fibers have better mechanical properties because of larger lamellae and higher degree of phase separation when the weight fraction of PBT is 40%.The fibers were prepared by melt spinning based on the thermoplastic poly(ether ester) elastomers of PBT40. Then the effect of spinning speed on the morphology structure and mechanical properties of PEE fibers was studied. It is found that the fibers have larger elastic recovery and tenacity because of large crystallinity and high orientation at high sinning speed. However, the elongation at break and shrinkage in boiling water decreased with the increasing spinning speed.Based on the study, the fibers have better elasticity but lower elastic recovery and higher shrinkage in boiling water. So an experiment was designed to study the morphology structure and mechanical properties of PEE fibers prepared by melt spinning in the speed of 500m/min based on PBT40 under different heat-treatment conditions changing with the time and temperature. It is found that the structure of larger lamellae, higher degree of phase separation and lower orientation of PEE fibers was formed under the heat-treatment without stress and the fibers have larger elastic recovery and elongation at break, smaller tenacity and shrinkage in boiling water. However, under the heat-treatment with stress at 100℃, more perfect crystalline structure including higher crystallinity and orientation of fibers formed, which leaded to better properties of PEE fibers.The further study about the effect of the heat-draw ratios on the fibers has been studied. The morphology of the fibers with different scales was studied as a function of heat-draw ratios by birefringence and SAXS, WAXS. It turned out that the orientation of crystal region and molecular chains increase when fibers were heat-drawn at larger ratios and larger size of lamellae acting as the physical force were formed, which could improve the tenacity and elastic recovery of PEE fibers. Besides, the elongation at break of PEE fibers declined because of the increasing orientation of non-crystalline region.