Simple in situ synthesis of copolymer compatibilizers for plastics recycling

消费后塑料回收受到以下事实的严重阻碍：多相聚合物饲料本质上是不相容的，这导致混合物中的相分离，以及回收产品的机械性能通常非常差。通过使用嵌段和接枝共聚物添加剂作为相容剂来改善聚合物共混物中的分散度和改善力学性能是一种公认的方法。不幸的是，这些材料的合成通常非常昂贵，因此不适合大规模的塑料回收。我们现在提出了一种原位生成接枝共聚体相容剂的方法，该方法基于KWI Solutions Polymères开发的一种新的深冷工艺，该工艺通过挤出工艺中的机械破碎将混合塑料饲料转化为细小(1-5微米)粉末。这会在颗粒表面产生大量的自由基物种，这是由于材料在裂解过程中发生的高分子链断裂过程。我们将研究使用混合微结构聚异戊二烯(PIP)作为裂解后添加剂，与存在的自由基物种反应，在挤出过程中原位生成相容的接枝共聚物。该项目将涉及产生不同分子量的PIP样品，这些样品可用于优化挤出条件并产生合适的增容剂。添加剂的性能将根据它们改善通过该方法获得的共混物的拉伸和冲击性能的能力进行评估。

Post-consumer plastics recycling is strongly hampered by the fact that heterogeneous polymer feeds areintrinsically immiscible, which leads to phase separation within the mixture and typically very poor mechanicalproperties for the recycled products. A well-established method to improve the degree of dispersion in polymerblends and to improve the mechanical properties is through the use of block and graft copolymer additives ascompatibilizers. Unfortunately these materials are generally very expensive to synthesize, and therefore notamenable to large scale plastics recycling. We now suggest a methodology to generate graft copolymercompatibilizers in situ, based on a new cryogenic process developed by KWI Solutions Polymères to turnmixed plastic feeds into fine (1-5 micrometer) powders by mechanical fracturing in an extrusion process. Thisgenerates a large number of radical species at the surface of the particles, due to the polymer chain-breakingprocesses taking place in fracturation of the materials. We will investigate the use of mixed microstructurepolyisoprene (PIP) as a post-fracturation additive to react with the free radical species present, to generatecompatibilizing graft copolymers in situ during the extrusion process. The project will be concerned withgenerating PIP samples of different molecular weights, that can be used to optimize the extrusion conditionsand generate suitable compatibilizing agents. The performance of the additives will be evaluated in terms oftheir ability to improve the tensile and impact properties of the blends obtained by that approach.