Efficient recycling of anhydride-cured epoxy resins for electrical insulation: Green economy and tunable performance

Abstract

The accumulation of resin-based electrical waste poses significant resource wastage and environmental challenges, with chemical recycling representing a key solution. This study innovatively developed a graded alcoholysis-hydrolysis reaction strategy, enabling both the efficient degradation of anhydride-cured epoxy resin within 1 h under mild conditions and the subsequent reuse of the degradation products in regeneration of new epoxy resins. Central to this work is a uniquely designed benzyl alcohol/K₃PO₄ recycling system, which enables the closed-loop utilization of not only the epoxy resin but also the system itself, owing to the facile separation of its components. Specifically, the average recovery rates of benzyl alcohol and K₃PO₄ can reach 80.38 % and 90.95 % over 10 cycles, while the recycling system constructed after 10 cycles using them retained over 80 % of degradation efficiency. Furthermore, the study systematically investigated the synthesis of new epoxy resins by adjusting the proportion of recycled resin. As the recycled resin content increased, the insulation performance of the regenerated resin improved, whereas its mechanical strength and thermal stability exhibited a decline. When the recycled resin content reached 30 wt%, the breakdown strength of the regenerated resin increased by 13.5 % compared to the pristine resin, while maintaining a flexural stress of 72.87 MPa and a glass transition temperature exceeding 100 °C. This research provides innovative insights and a theoretical foundation for advancing green decommissioning technologies for resin-based electrical equipment.