A growing demand in polylactic acid (PLA) has increased in recent years due to the increasing of non-degradable plastic wastes. The recycling of PLA waste is seen to be another permissible solution to conserve the resources. This work aims to study the degradation rate of virgin PLA (VPLA) and recycled PLA (RPLA) in terms of the mechanical properties after ageing in different aqueous environment. The samples were immersed in river water (RW) and seawater (SW) for the duration of 150 days. Tensile strength, transverse rupture strength (TRS), impact energy and hardness properties were investigated as a function of immersed time. The results revealed that the loss in the tensile strength accelerated in river water when compared to seawater. There was at least 50% of tensile strength sacrificed in recycled PLA. The TRS had dropped approximately half from its initial value after ageing in river water and about 30% after ageing in seawater. Besides, a huge decrease ranging around 70-80% from its initial impact energy was identified. However, the reduction in hardness was relatively low. The findings will help to elucidate the degradation process of PLA and the desired effect on the mechanical performance for further application.

由于不可降解塑料废物的增加，近年来对聚乳酸 (PLA) 的需求不断增长。回收 PLA 废料被认为是另一种保护资源的可行解决方案。本工作旨在研究原始 PLA (VPLA) 和再生 PLA (RPLA) 在不同水性环境中老化后的机械性能的降解率。将样品浸入河水 (RW) 和海水 (SW) 中 150 天。拉伸强度、横向断裂强度 (TRS)、冲击能和硬度特性作为浸泡时间的函数进行了研究。结果表明，与海水相比，河水中的抗拉强度损失加速。回收的 PLA 至少牺牲了 50% 的拉伸强度。在河水中老化后，TRS 比其初始值下降了大约一半，在海水中老化后下降了约 30%。此外，还发现其初始冲击能大幅下降约 70-80%。然而，硬度的降低相对较低。这些发现将有助于阐明 PLA 的降解过程以及对进一步应用的机械性能的预期影响。