Natural environment aging of virgin and recycled poly(lactic acid): a comparative study on outdoor weathering, seawater and river water

Due to serious environmental pollution which is derived from petroleum-based plastic wastes, poly(lactic acid) (PLA) has been seen as a potential bioplastic to overcome the problem. It has been predicted that the usage and disposal of PLA will continuously increase in the coming years. Recycling is one of the realistic ways to minimize resources and waste management. This work intended to investigate the degradation or mechanical properties of virgin PLA (VPLA) and recycled PLA (RPLA) aged in outdoor weathering and immersed in seawater and river water. The results demonstrated that the reduction in mechanical properties was most dominant in river water, which was aged for 150 days. The findings demonstrated that the reduction in mechanical properties was higher in RPLA than VPLA. Scanning electron microscopy images showed the formation of gullies on the fracture surface of samples aged in seawater and river water. No significant differences in thermal properties were observed in RPLA and VPLA after aging in outdoor weathering. Nevertheless, a marginal decrease in the glass transition temperature (T-g), melting temperature (T-m), and degradation temperature was observed after aging in seawater and river water. The findings could help in elucidating the degradation on mechanical and thermal properties of VPLA and RPLA. The results also revealed great significance for expanding the application of VPLA and RPLA in various environments. [GRAPHICS] .