Fiber structure development in high-speed melt spinning of poly(ethylene terephthalate-co-ethylene 2,6-naphthalene dicarboxylate)

摘要

High-speed melt spinning of Poly(ethylene terephthalate-co-ethylene 2,6-naphthalene dicarboxylate) (P(ET/EN)) with EN content of 8% was performed. The structure and mechanical properties of the as-spun fibers thus produced in the take-up velocity range of 0.5 to 7.5 km/min were characterized and compared with those of high-speed spun PET fibers. Molecular orientation increased with an increase in the take-up velocity. The development of molecular orientation of P(ET/EN) was more significant than that of PET at low take-up velocities. Accordingly, orientation-induced crystallization of P(ET/EN) started to occur at a slightly lower take-up velocity compared with PET. On the other hand, the maximum birefringence of P(ET/EN) attained at about 6 km/min was lower than that of PET. Although the crystallization temperature estimated from the thinning behavior of the spinning line is similar, density of P(ET/EN) as-spun fibers obtained at high-speed region was significantly lower than that of PET fibers indicating that the crystallization into PET crystals was suppressed by the addition of EN component to PET.