Melt-spun polylactide/ethylene vinyl alcohol copolymer fiber

Polylactide/ethylene vinyl alcohol copolymer (PLA/EVOH) blends and fibers with different weight ratios were prepared by melt blending, and two-step melt spinning, respectively. PLA and EVOH in PLA/EVOH blends were immiscible. When EVOH content was ≤60 %, EVOH with the average diameter of about 3 μm was dispersed in PLA matrix uniformly. The dual continuous phases could be observed in PLA/EVOH blend with 70 wt% EVOH. When the EVOH content was ≥80 %, the spherical PLA phase with the diameter of 0.25 to 1 μm was dispersed in EVOH matrix. The introduction of EVOH as nucleating agent could promote the crystallization of PLA. Both PLA and EVOH components in PLA/EVOH blends formed individual crystal phases. The viscosity of PLA/EVOH blend with 5 % EVOH was lower than that of neat PLA. The viscosity of PLA/EVOH blends with the EVOH content of ≥10 % was much higher than that of neat PLA, which showed obvious shear thinning behavior. With the increase of EVOH content, the shear thinning behavior became obvious and the critical shear rate decreased gradually. The drawn PLA/EVOH fibers with the tensile strength of ≥16 cN/tex exhibited good mechanical properties. In addition, the introduction of EVOH could improve the hydrophilicity of PLA fibers.