A novel macromolecular auxiliary antioxidant with polyethylene (PE) as polymer skeleton and phosphites as side groups is prepared based on commercial ethylene‐vinyl acetate (EVA) copolymers and its potential as polyolefin stabilizers is studied in depth. The synthesis approach of this PE‐grafted antioxidant consists of a typical EVA hydrolysis reaction and a two‐step nucleophilic substitution reaction of PCl₃, 2,4‐di‐tert‐butylphenol, and the hydrolysis product. Results of the thermogravimetric analysis show that the macromolecular structures endow the as‐synthesized antioxidant with much better thermal stability than that of the commercial antioxidant 168. In addition, antioxidant behaviors of the PE‐grafted antioxidants in polypropylene (PP) matrix are investigated in detail through characterization of the melt flow index of multiple‐extruded stabilized PP as well as the short‐term oxidation induction time test and the long‐term thermo‐oxidative aging test. Results show that even with extremely low content of the effective antioxidant groups, the as‐synthesized macromolecular antioxidant still has excellent antioxygenic properties.

中文翻译：

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聚乙烯接枝亚磷酸酯抗氧化剂的合成及其在聚丙烯中的抗氧化性能

以商业化的乙烯-醋酸乙烯酯（EVA）共聚物为基础，制备了以聚乙烯（PE）为聚合物骨架，亚磷酸酯为侧基的新型高分子辅助抗氧化剂，并深入研究了其作为聚烯烃稳定剂的潜力。这种PE接枝的抗氧化剂的合成方法包括典型的EVA水解反应和PCl _3的两步亲核取代反应，2,4-二叔丁基苯酚和水解产物。热重分析的结果表明，大分子结构赋予合成的抗氧化剂比商业抗氧化剂168更好的热稳定性。此外，还详细研究了PE接枝的抗氧化剂在聚丙烯（PP）基体中的抗氧化行为。通过多次挤压稳定PP的熔体流动指数的表征以及短期氧化诱导时间测试和长期热氧化老化测试来表征。结果表明，即使有效抗氧化剂基团的含量极低，合成的高分子抗​​氧化剂仍具有优异的抗氧性能。