Sirisinha Kalyanee, Wirasate Supa, Sirisinha Chakrit, Wattanakrai Noppasorn
Department of Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
Rubber Technology Research Centre (RTEC), Faculty of Science, Mahidol University, Nakhon Prathom 73170, Thailand.
Polymers (Basel). 2022 Sep 2;14(17):3642. doi: 10.3390/polym14173642.
Post-consumer waste recycling is a crucial issue for building a sustainable society. However, mechanical recycling of poly(lactic acid) (PLA) often reduces the performance of the recycled material because PLA has a strong tendency to degrade during reprocessing. Therefore, it is of great interest to develop an effective recycling method to improve the mechanical performance of this material. This paper presents a one-pot melt process for turning PLA waste into a biodegradable block copolymer and its high strength and ductility composite. The process was conducted in a melt-mixer through a transesterification of PLA with poly(ethylene glycol) (PEG) or poly(propylene glycol) (PPG) as a soft component and clay as reinforcement. Effects of soft component content and sequence of clay addition on the mechanical performance of the prepared materials were focused. The results showed the successful preparation of PLA-based multiblock copolymers of high molecular weights (~100 kDa). Both virgin PLA and recycled source could serve as the starting material. PEG was more efficient than PPG in providing an intense improvement of PLA ductility. The nanocomposite of intercalated structure yielded nearly 100 times higher elongation at break (E = 506%) than the starting PLA (E = 5.6%) with high strength of 39.5 MPa and modulus of 1.4 GPa, considering the advantages of clay addition. Furthermore, the products with a broadened range of properties can be designed based on the ratio of PLA and soft component, as well as the organization and spatial distribution of clay in the copolymer matrices.
消费后废弃物回收是建设可持续社会的关键问题。然而，聚乳酸（PLA）的机械回收往往会降低回收材料的性能，因为PLA在再加工过程中有很强的降解倾向。因此，开发一种有效的回收方法以提高这种材料的机械性能具有重要意义。本文提出了一种将PLA废料一锅法熔融制备可生物降解嵌段共聚物及其高强度和高韧性复合材料的方法。该过程在熔融混合器中进行，通过PLA与作为软组分的聚乙二醇（PEG）或聚丙二醇（PPG）进行酯交换反应，并以粘土作为增强剂。重点研究了软组分含量和粘土添加顺序对所制备材料机械性能的影响。结果表明成功制备了高分子量（约100 kDa）的PLA基多嵌段共聚物。原始PLA和回收原料均可作为起始材料。在显著提高PLA韧性方面，PEG比PPG更有效。考虑到添加粘土的优势，插层结构的纳米复合材料的断裂伸长率（E = 506%）比原始PLA（E = 5.6%）高出近100倍，具有39.5 MPa的高强度和1.4 GPa的模量。此外，基于PLA与软组分的比例以及粘土在共聚物基体中的排列和空间分布，可以设计出具有更广泛性能范围的产品。
