Theoretical Study on Decomposition Mechanism of Insulating Epoxy Resin Cured by Anhydride

High temperatures caused by partial discharge results in the decomposition of insulating epoxy resins in electrical equipment. In this paper, the ReaxFF force field is used to investigate the decomposition process of epoxy resins cured by anhydride and the formation mechanisms of small-molecule gases. Results show that the initiation reaction is the cleavage of an ester bond linked with an epoxy resin. Produced by the decomposition of ester groups, CO2 is the first and most abundant product. Meanwhile, CH2O can be generated through three main ways, although the process still depends on the decomposition of epoxy functional groups. H2O is produced by free radical collision and dehydration. The production of small-molecule gases has the following sequence: CO2, CH2O, CO, and H2O. The produced gases have the following order according to amount: CO2, CH2O, H2O, and CO.