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.