Thermal Decomposition Properties of Epoxy Resin in SF(6)/N(2) Mixture

As a promising alternative for pure SF(6), the mixture of SF(6)/N(2) appears to be more economic and environment-friendly on the premise of maintaining similar dielectric properties with pure SF(6). But less attention has been paid to the thermal properties of an SF(6)/N(2) mixture, especially with insulation materials overheating happening simultaneously. In this paper, thermal decomposition properties of epoxy resin in SF(6)/N(2) mixture with different SF(6) volume rates were studied, and the concentrations of characteristic decomposition components were detected based on concentrations change of some characteristic gas components such as CO(2), SO(2), H(2)S, SOF(2), and CF(4). The results showed that thermal properties of 20% SF(6)/N(2) (volume fraction of SF(6) is 20%) mixture has faster degradation than 40% SF(6)/N(2) mixture. As ratio of SF(6) content decreases, thermal stability of the system decreases, and the decomposition process of SF(6) is exacerbated. Moreover, a mathematical model was established to determine happening of partial overheating faults on the epoxy resin surface in SF(6)/N(2) mixture. Also thermal decomposition process of epoxy resin was simulated by the ReaxFF force field to reveal basic chemical reactions in terms of bond-breaking order, which further verified that CO(2) and H(2)O produced during thermal decomposition of epoxy resin can intensify degradation of SF(6) dielectric property.