Impact of plasma‐treated nano‐alumina on the thermal and electrical properties of epoxy resin at elevated temperatures

Abstract In this study, to ramp up the thermal stability and insulation characteristics of epoxy resin (EP), the plasma‐treated EP/alumina composites with a mass fraction of 1 wt% were fabricated. The variations of functional groups in the EP composites with/without plasma treatment were characterized by Fourier transform infrared spectroscopy (FTIR), and the glass transition temperature of the specimens was analyzed by differential scanning calorimetry (DSC) analysis. The space charge distributions, the electrical conductivity and DC breakdown strength of the specimens were measured at 90°C. Moreover, the results were further analyzed in depth. The results indicated that the nanocomposites prepared with plasma‐treated nano‐alumina exhibited a higher concentration of OH and CO groups. At 90°C, the plasma‐treated alumina nanoparticles significantly increased the charge injection threshold of EP from about 26 nC (untreated) to 19 nC (treated); reduced the internal electric field distortion, decreased the charge accumulation and dissipation, and increased the breakdown strength from about 104 kV/mm (untreated) to 115 kV/mm (treated), and the conductivity from about 5.1 × 10⁻¹⁴ S/m (untreated) to 3.1 × 10⁻¹⁴ S/m (treated). In summary, it was elucidated that plasma‐treated nano‐alumina particles could effectively reduce deep trap density, trapped charges, charge injection and transportation and reinforce composites' insulation performance at high temperatures. Highlights The DBD plasma treatment is environmentally friendly with high efficiency. The testing adopted advanced characterization and analysis techniques. Plasma treatment of alumina nanoparticles enhanced the thermal stability. The treated nano‐alumina reinforced insulation performance of EP nanocomposites. The plasma treatment raised the space charge injection threshold and barrier.