2026/07/27 by Qiuli Tao, Mingfang Zou, Siqi Zhao +6
paper · doi:10.1088/1361-6463/ae90bc
Abstract Thermal-oxidative aging of synthetic ester oil-paper insulation is closely associated with acid-catalyzed depolymerization of cellulose, in which hydronium ions play a key role at the oil-paper interface. In this work, KH550-modified hexagonal boron nitride (KH550-hBN) nanoparticles were introduced into a synthetic ester oil-paper insulation system to examine whether the nanoparticle interface can regulate the interaction and transport behavior of hydronium ions during aging. Accelerated thermal aging was carried out at 155 °C in air, and the evolution of acid value, dielectric loss, AC breakdown strength, tensile strength, and degree of polymerization (DP) was evaluated. Compared with the unmodified system, the nanomodified system showed lower dielectric loss and acid value, while the DP of the impregnated paper remained 13.5% higher after 672 h of aging. Kinetic analysis based on the DP data further showed that the cellulose degradation rate constant decreased by 21.1% after nanoparticle incorporation. SEM observations confirmed that the modified paper retained a more intact fiber morphology with fewer cracks after prolonged aging. To clarify the underlying mechanism, molecular dynamics simulations were performed using the Universal force field. The results showed that KH550-hBN weakens the interaction between cellulose and hydronium ions, reduces hydrogen-bond formation between them, and suppresses hydronium-ion diffusion. These findings indicate that the functionalized nanoparticle interface reduces both the tendency of hydronium ions to approach cellulose and their mobility near the oil-paper interface, thereby slowing acid-catalyzed cellulose degradation. This work provides a mechanism-based explanation for the improved aging stability of nanomodified ester-based oil-paper insulation.