Degradation of 3D-printed poly(lactic acid) for biomedical applications

The biocompatibility, biodegradability and bioreabsorbability properties of PLA make it an attractive material for biomedical applications, especially in implantable devices. Nevertheless, the degradation of this material in biological media under mechanical stress has not yet been fully explored and needs further understanding. Thus, the motivation of this research is to evaluate changes in the properties of 3D-printed PLA when exposed to a simulated biological media, for possible applications in implantable devices. This work aimed to evaluate changes in properties of PLA parts manufactured through 3D printing when immersed in saline phosphate solution for periods of (7, 14 and 30) days. The material was evaluated for mass change, chemical changes (Fourier transform infrared spectroscopy-FTIR), glass transition temperature (dynamic mechanical analysis), flexural properties (3-point bending tests) and fatigue behaviour. Results showed an increase in mass after immersion for 7 days followed by a decrease in mass for samples immersed for 14 days and 30 days. It was found that immersion in saline phosphate solution produced chemical alterations and increase in glass transition temperature. Although no significant changes were observed in flexural strength after immersion, an average reduction in fatigue life of 57% for 0.25% strain amplitude and 77% for 1% strain amplitude was observed for immersed samples. The results presented suggest that printed PLA can be a promising alternative for applications such as drug delivery and tissue engineering.