Molecular Simulation Insights Into Nano‐SiC/SiR and Nano‐SiO2/SiR Composites for Improving Moisture Resistance, Charge Trapping Ability, and Thermal Stability

ABSTRACT Through a comprehensive set of molecular dynamics (MD) simulations, Monte Carlo molecular simulations, and first‐principles calculations, the addition‐curing silicone rubber (SiR) nanocomposites with silicon carbide (SiC) or silica (SiO 2 ) nanofiller are investigated to reveal the underlying physics and chemistry of utilizing nanodielectric technology to improve electrical insulation performance, moisture resistance, and thermal stability of the SiR material used for cable accessories. On a molecular‐scale level, the present study estimates and predicts the microstructures, thermodynamic properties, and water self‐diffusion and adsorption in these SiR matrixed nanocomposites. Specifically, a higher nanofiller content reduces free volume density, accounting for the decreased water uptake and diffusion, which imply the enhancement of moisture resistance in the SiR nanocomposites. Additionally, the increased nanofiller content enhances the restriction on thermal vibrations of SiR polymer chains, thereby further improving thermal stability and inhibiting electrothermal breakdown for addition‐curing SiR material. In particular, the electronic properties of nanofiller/SiR interfaces are calculated by a first‐principles approach to demonstrate these nanofillers introduce charge traps into the addition‐curing SiR nanocomposites, thus impeding charge transport and suppressing space charge accumulations. Aiming to theoretically elucidate the thermal‐shock pyrolysis under the heat effect of partial discharge in the SiR nanocomposites, the barostatic anneal reactive MD simulations are performed to evaluate the effects of SiC and SiO 2 nanofillers on the pyrolysis tolerance of addition‐curing SiR material according to the inception temperature, mass density, internal potential energy, and major molecular or free‐radical products in the simulated pyrolysis processes. The results highlight the importance of nanofiller concentration in determining the overall performance of the SiR nanocomposites, suggesting that higher nanofiller content can lead to more effective improvements in thermal stability and moisture resistance, as well as pyrolysis tolerance.