Simple in situ synthesis of copolymer compatibilizers for plastics recycling

非均相聚合物进料本质上是不混溶的，这导致混合物内的相分离和回收产品通常非常差的机械性能，这严重阻碍了消费后塑料的回收。一种行之有效的方法来提高在聚合物共混物中的分散度和改善机械性能是通过使用嵌段和接枝共聚物添加剂作为增容剂。不幸的是，这些材料的合成通常非常昂贵，因此不能进行大规模的塑料回收。我们现在提出了一种原位生成接枝共聚物增容剂的方法，该方法基于KWI Solutions Polymères开发的一种新的低温工艺，该工艺通过挤出过程中的机械破碎将混合塑料进料变成细粉（1-5微米）。这在颗粒的表面产生大量的自由基物种，由于聚合物链断裂过程发生在材料的断裂中。我们将研究使用混合微观结构聚异戊二烯（PIP）作为压裂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性接枝共聚物。该项目将关注生产不同分子量的PIP样品，这些样品可用于优化挤出条件并产生合适的相容剂。添加剂的性能将根据其改善通过该方法获得的共混物的拉伸和冲击性能的能力来评估。

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.