Abstract
Degradation rate of bioabsorbable polymer is affected by molecular weight and crystallinity. In this study, effect of thermal treatment on biodegradation of poly (lactic acid) (PLA) was investigated. Annealing was conducted on PLA specimen. Annealing temperature was selected as 70 ℃ and 130 ℃. Three types of specimens is used ; non-annealing, 70℃-annealing, 130℃-annealing. Crystallinity was also measured. Immersion tests were conducted to measure weight change of the specimen. Crystallinity increased with annealing temperature. Water absorption of the specimen annealed was smaller than that of non-annealing specimen, because the specimen with higher crystallinity has less space which water molecular invade. Young's moduli for the non-annealing and 70℃-annealing specimens were close, whereas the 130℃-annealing specimen was larger because of increasing deformation resistance due to increasing crystallinity. Fracture strength for the non-annealing and 70℃-annealing specimens were also close, however strength for the 130℃-annealing specimen was much smaller because of embrittlement due to successive crystallization.
