Structure Mediation and Properties of Poly(l-lactide)/Poly(d-lactide) Blend Fibers

Poly(l-lactic acid) (PLLA) and poly(d-lactic acid) (PDLA) blend as-spun fibers (50/50, wt.%) were prepared by melt spinning. Structure mediation under temperature and stress and properties of poly(l-lactic acid)/poly(d-lactic acid)(PLLA/PDLA) as-spun fibers were investigated by wide-angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC). The results show that highly oriented stereocomplex (SC) crystals can be formed in PLLA/PDLA blend fibers drawn at 60 degrees C and annealed at 200 degrees C. However, at drawn temperature of 80 degrees C, only lower oriented SC crystals can be formed. For PLLA/PDLA blend fibers drawn twice at 60 degrees C (PLLA/PDLA-60-2), the crystallinity of SC crystals increases with annealing temperature in the range of 200 to 215 degrees C, while the degree of orientation decreases slightly. When the annealing temperature is 210 degrees C, the crystallinity and orientation of SC crystals in PLLA/PDLA-60-2 fibers reach 51% and -0.39, respectively. Moreover, PLLA/PDLA-60-2-210 fibers exhibit excellent heat-resistant property even at 200 degrees C. The results indicate that the oriented PLLA/PDLA blend fibers with high SC crystals content can be regulated in a short time.