In vitro temperature-dependent degradation of polylactic acid: Experimental characterization and neural network-based prediction

초록

To ensure the reliable use of polylactic acid (PLA) as a medical polymer, it is essential to develop a model that can accurately assess the degradation of its mechanical properties under in vitro conditions. In this study, PLA was immersed in phosphate buffered saline at 37 degrees C to investigate its degradation behavior. A marked decline in tensile strength was observed following an induction period, with surface analysis revealing that diffusion-limited hydrolysis (DLH) characterized by the formation of hydrolysis-induced micro-pits and cracks was the primary degradation mechanism. Chain scission and crystallization behavior resulting from hydrolysis were systematically examined. Using experimental data obtained at elevated temperatures (50, 60, and 70 degrees C), crystallization kinetics were modeled using the Avrami equation, enabling the development of a predictive relationship between tensile strength and crystallinity. Furthermore, an artificial neural network was employed to construct a model capable of accurately predicting tensile strength across a range of temperatures and exposure durations, thereby enhancing the reliability of PLA for in vitro applications.

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