The aim of this work is to study the effects of different simulated mechanical recycling processes on the structure and properties of PLA. A commercial grade of PLA was melt compounded and compression molded, then subjected to two different recycling processes. The first recycling process consisted of an accelerated ageing and a second melt processing step, while the other recycling process included an accelerated ageing, a demanding washing process and a second melt processing step. The intrinsic viscosity measurements indicate that both recycling processes produce a degradation in PLA, which is more pronounced in the sample subjected to the washing process. DSC results suggest an increase in the mobility of the polymer chains in the recycled materials; however the degree of crystallinity of PLA seems unchanged. The optical, mechanical and gas barrier properties of PLA do not seem to be largely affected by the degradation suffered during the different recycling processes. These results suggest that, despite the degradation of PLA, the impact of the different simulated mechanical recycling processes on the final properties is limited. Thus, the potential use of recycled PLA in packaging applications is not jeopardized.

这项工作的目的是研究不同的模拟机械回收工艺对PLA的结构和性能的影响。将商品级的PLA熔融混炼并压制成型，然后进行两种不同的回收过程。第一回收过程包括加速老化和第二熔体加工步骤，而另一回收过程包括加速老化，苛刻的洗涤过程和第二熔体加工步骤。特性粘度的测量结果表明，两个循环过程均会导致PLA降解，这在经过洗涤过程的样品中更为明显。DSC结果表明，回收材料中聚合物链的迁移率增加。但是，PLA的结晶度似乎没有变化。光学的 在不同的回收过程中，PLA的机械和阻气性能似乎不会受到很大的影响。这些结果表明，尽管PLA降解，但不同的模拟机械回收工艺对最终性能的影响仍然有限。因此，回收的PLA在包装应用中的潜在用途不会受到危害。