Addressing the mounting issue of plastic waste, particularly the recycling of polyethylene (PE) and isotactic polypropylene (iPP), requires inventive and economically viable solutions. Employing compatibilizers for physical recycling is one of the most promising ways. This study utilizes reversible free radical reaction to facilitate the grafting reaction of ethylene propylene diene monomer (EPDM) between PE (or iPP) at the interface. Only 1 wt%-3wt.% EPDM is required for reactive blending, resulting in the formation of a graft multi-block copolymer that significantly improves the compatibility between PE and PP. This improvement notably enhances the mechanical properties, especially the elongation at break, which can reach up to 700 %. Even after three processing cycles, the elongation at break of samples can still reach approximately 400 %. The mechanism for reactive compatibilization has been supported by various characterization techniques, including tensile, rheology, peeling, and transmission electron microscope (TEM) tests. The mechanical properties of the samples were diminished when EPDM was replaced by the synthesized copolymer of ethylene and ethylidene norbornene (CEENB) and vinyl-terminated polyethylene (VPE). This observation confirms that EPDM located at the PE/iPP interface significantly contributes to the formation of grafted multi-block copolymers. Notably, the grafting reaction causes a negligible shift in the molecular weight peak, indicating minimal degradation and cross-linking of the polymers. The reversible free radical reaction involving sulfur and tetramethyl thiuramyl monosulfide (TMTM) reagents plays an important role in reducing side reactions.

中文翻译：

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原位接枝三元乙丙橡胶多嵌段共聚物作为聚乙烯 （PE） 和等规聚丙烯 （iPP） 共混物的相容剂


解决日益严重的塑料废弃物问题，特别是聚乙烯 （PE） 和等规聚丙烯 （iPP） 的回收利用，需要创造性且经济可行的解决方案。使用增容剂进行物理回收是最有前途的方法之一。本研究利用可逆自由基反应促进三元乙丙橡胶 （EPDM） 在界面处 PE（或 iPP）之间的接枝反应。反应共混只需要 1wt.%-3wt.% 的 EPDM，从而形成接枝多嵌段共聚物，显着改善 PE 和 PP 之间的相容性。这种改进显著提高了机械性能，尤其是断裂伸长率，最高可达 700%。即使经过三个处理周期，样品的断裂伸长率仍可达到约 400%。反应相容性机制得到了各种表征技术的支持，包括拉伸、流变学、剥离和透射电子显微镜 （TEM） 测试。当 EPDM 被乙烯和亚乙基降冰片烯 （CEENB） 和乙烯基封端聚乙烯 （VPE） 的合成共聚物取代时，样品的机械性能降低。这一观察结果证实，位于 PE/iPP 界面的 EPDM 对接枝多嵌段共聚物的形成有显著贡献。值得注意的是，接枝反应引起的分子量峰偏移可以忽略不计，表明聚合物的降解和交联最小。涉及硫和四甲基硫拉酰一硫化物 （TMTM） 试剂的可逆自由基反应在减少副反应方面起着重要作用。