Hydrolysis Kinetics of Poly(lactic acid) Fiber

In vitro degradation of poly(lactic acid) (PLA) fibers were investigated in the phosphate-buffered solution (pH 6.86) at 50, 70, and 90 °C, respectively. Three kinds of fibers, with different birefringence and crystallinity, were prepared by melt-spinning and drawing processes. During the hydrolysis, the crystallization of lower orientation and lower crystallinity fiber was observed at 50 °C, which is lower than the glass transition temperature of PLA. This may be caused by the degradation in the amorphous region. The degradation rate constant of lower birefringence (0.000) and lower crystallinity (9.7%) fiber was 1.5-3.0 times faster than that of higher (0.030 and 39.6%) one.