Surface Morphology for Poly-L-lactide Fibers Subjected to Hydrolysis Suong-Hyu Hyon Institute for Frontier Medical Sciences, Kyoto University 53, Shog

Surface Morphology for Poly-L-lactide Fibers Subjected to Hydrolysis Suong-Hyu Hyon Institute for Frontier Medical Sciences, Kyoto University 53, Shogoin Kawaharacho, Sakyo-ku, Kyoto, 606-8507 Japan Abstract: The surface morphological changes in poly-l-lactide (PLLA) fibers subjected to in vitro hydrolysis at 37 Ž and 100 Ž have been investigated by observation with scanning electron microscopy. PLLA was melt-spun in air at 200 Ž with an extruder of screw-type. Hot drawing and heat treatment of the fibers were conducted at 80-160'C. The wide-angle X-ray diffraction patterns of the drawn fibers showec appreciable crystalline orientation. Hydrolytic degradation of as-spun and drawn fibers was conducted it distilled water at 37 Ž and 100 'C, The tensile strength after 6 months at 37 Ž dropped only 10 % with nc change in water. On the other hand, hydrolysis at 100'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. (Received 29 May, 1998: Accepted 3 August, 1998)

Table 1 Polymerization conditions and characteristics of polymer used for melt spinning Fig. 1 X-ray diffraction photographs for PLLA at 140 C. The draw ratios are given in the photos. fibers drawn at 80'C, followed by annealing

Fig. 2 SEM of PLLA fibers (drawn at 80 Ž, followed by annealing at 140 Ž. Draw ratio is 3 times) subjected to in vitro hydrolysis in distilled water at 37 *C. (A)hydrolysis duration for 3 months (B)hydrolysis duration for 6 months Fig. 3 Decrease in tensile strength and mass for PLLA fiber (drawn at 80 Ž, followed by annealing at 140 Ž. Draw ratio is 3 times) hydrolyzed in distilled water at 100 Ž. (O)strength of PLLA, (a)mass of PLLA.

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