Thermo-Oxidative Ageing of Degradable Resins Based on Different Transesterification Catalysts

This study investigates the influence of different transesterification catalysts on the performance evolution of degradable epoxy resins under thermal-oxidative ageing. Three resin systems were prepared using triethanolamine (TEOA), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), and zinc acetylacetonate as catalysts, followed by ageing tests at 220°C. The effects of ageing time and catalyst type on the electrical, thermal, mechanical properties and degradation behaviour of the resins were systematically analysed. Results reveal that prolonged ageing causes certain performance degradation, yet the resins still maintain favourable overall properties at the late ageing stage. The V-TEOA system shows the best performance retention after 42 days of ageing, with key indicators as follows: breakdown strength 36.7 kV/mm, dielectric loss factor 0.46%, leakage current 65.34 μA, flexural strength 67.32 MPa and temperature index 170.99°C. Meanwhile, thermal-oxidative ageing markedly weakens the degradation efficiency of the resins, and a distinct core–shell structure is found in the degraded V-TBD system. This work deepens the understanding of ageing behaviours of such resins and supports their practical application in the engineering.