Surface morphology for poly-L-lactide fibers subjected to hydrolysis

The surface morphological changes in poly-L-lactide (PLLA) fibers subjected to in vitro hydrolysis at 37 degrees C and 100 degrees C have been investigated by observation with scanning electron microscopy. PLLA was melt-spun in air at 200 degrees C with an extruder of screw-type. Hot drawing and heat treatment of the fibers were conducted at 80 similar to 160 degrees C. The wide-angle X-ray diffraction patterns of the drawn fibers showed appreciable crystalline orientation. Hydrolytic degradation of as-spun and drawn fibers was conducted in distilled water at 37 degrees C and 100 degrees C. The tensile strength after 6 months at 37 degrees C dropped only 10 % with no change in water. On the other hand, hydrolysis at 100 degrees C caused a 100 % decreased in tensile strength for fiber within 20 hr. SEM examination of these fibers revealed regular patterns of cracks running in the vertical direction to the fiber axis.