Temperature effects on the sheath-core bar interface of composite insulators: a molecular dynamics and DFT study

Abstract The functioning condition of composite insulators is greatly influenced by the sheath-mandrel interface. In this work, the effects of temperature on the sheath-mandrel system are examined using molecular modeling, taking into account both density functional theory (DFT) and molecular dynamics (MD). The system’s interfacial free volume, HOMO/LUMO, number of hydrogen bonds, bond order, center-of-mass distance, and other characteristics define its degradation mechanism. The findings demonstrate that elevated temperatures have the potential to increase the interfacial free volume, the center-of-mass distance, and significantly reduce the number of hydrogen bonds. In addition, DFT simulations show that the bonding strength and non-bonding forces between the interfaces weaken with increasing temperature. High temperatures significantly boost the reactivity of the epoxy resin and silicone rubber chains, indicating that the system’s response with some intruders will be catalyzed by the temperature increase. This work looks at the temperature dependence of the sheath-core bar interface degradation from a microscopic perspective, which is important for enhancing the overall performance of composite insulators.