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.

Silica–epoxy nanocomposite models were established to investigate the influence of silane coupling agent on the structure and thermomechanical properties of the nanocomposites through molecular dynamics simulation. Results revealed that incorporating silica nanoparticles into a polymer matrix could improve thermomechanical properties of the composites and increase their glass transition temperature and thermal conductivity. Their thermomechanical properties were further enhanced through silane coupling agent modification on the surface of fillers. Compared with that of pure epoxy, the glass transition temperatures of the silica–epoxy composites with grafting ratios of 5% and 10% increased by 17 and 28 K, respectively. The thermal conductivities of the two models at room temperature respectively increased by 60.0% and 67.1%. At higher temperature 450 K, thermal conductivity of the nanocomposite model with a high grafting ratio of 10% demonstrated a considerable increase of approximately 50% over the pure epoxy resin (EP) model. The elastic and shear modulus of the nanocomposite models decreased at temperatures below their glass transition temperatures. These observations were further addressed in the interpretation from three aspects: segmental mobility capability, radial distribution function, and free volume fraction. Our computational results are largely consistent with existing experimental data, and our simulation model got fully validated.

As a promising alternative for pure SF₆, the mixture of SF₆/N₂ appears to be more economic and environment-friendly on the premise of maintaining similar dielectric properties with pure SF₆. But less attention has been paid to the thermal properties of an SF₆/N₂ mixture, especially with insulation materials overheating happening simultaneously. In this paper, thermal decomposition properties of epoxy resin in SF₆/N₂ mixture with different SF₆ volume rates were studied, and the concentrations of characteristic decomposition components were detected based on concentrations change of some characteristic gas components such as CO₂, SO₂, H₂S, SOF₂, and CF₄. The results showed that thermal properties of 20% SF₆/N₂ (volume fraction of SF₆ is 20%) mixture has faster degradation than 40% SF₆/N₂ mixture. As ratio of SF₆ content decreases, thermal stability of the system decreases, and the decomposition process of SF₆ is exacerbated. Moreover, a mathematical model was established to determine happening of partial overheating faults on the epoxy resin surface in SF₆/N₂ 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 CO₂ and H₂O produced during thermal decomposition of epoxy resin can intensify degradation of SF₆ dielectric property.

SrTiO₃/epoxy nanocomposites are prepared using the facile solution-processing technique by incorporating SrTiO₃ nanoparticles with different weight fractions into the epoxy resin host. The morphology of the nanoparticles and composites, as well as the thermal conduction characteristics and electrical properties of the composites were investigated via conventional testing methods. The thermal conductivity increased along with the SrTiO₃ weight fractions, and the thermal conductivity of the SrTiO₃/epoxy composite with 40 wt % weight fraction increased to 0.52 W/mK. The dielectric constant increased along with the weight fractions and decreased along with frequency, thereby suggesting that the interfacial and dipole polarization do not follow the changes in the electrical field direction at high frequency. The dielectric constants at 1 kHz frequency increased along with temperature. Surface breakdown tests illustrated further improvements in the thermal and electrical properties of the composites. In the same time span of 40 s, the 40 wt % nanocomposite demonstrated a rapid temperature decline rate of 6.77 °C/s, which was 47% faster than that of the pure epoxy sample. The surface breakdown voltage also increased along with the weight fractions. The functional composites can solve the key problem in the intelligentization, miniaturization, and high-efficiency of the gas-insulated switchgear, which warrants further research.

In this paper, the flashover discharging experiment was carried out on epoxy resin surface in an SF₆ atmosphere under pin-plate electrodes, with the electrodes distance from 5 mm to 9 mm. The concentration of seven characteristic gases was detected, indicating that the concentration of SOF₂ and CF₄ was the two highest, followed by SO₂, CO₂, SO₂F₂, CS₂, and H₂S. Based on the changes in the concentration of the characteristic gases, a preliminary rule was proposed to predict the occurrence of flashover discharge on epoxy resin: When the concentration of SOF₂ reaches twice of CF₄ concentration, and the total concentration of both SOF₂ and CF₄ is much higher than that of H₂S, a possible flashover discharge on the epoxy resin surface in SF₆-infused electrical equipment occurs. Through the simulation of decomposition of epoxy resin, it has been revealed that H₂O has different generation paths that can facilitate the formation of SOF₂, finally influencing the concentration variation of the seven characteristic gases.