Effect of external electric field on the microstructure of FEPM rubber insulation based on molecular simulation

The excellent electrical properties of tetrafluoroethylene-propylene elastomer (FEPM) rubber make it widely used in electrical insulation materials. In this study, density functional theory is employed to investigate the microstructural and space charge characteristics changes of FEPM rubber under an external electric field. The results demonstrate that as the electric field intensity increases, the total energy decreases while the dipole moment and polarizability increase, leading to a decrease in the stability of FEPM. The molecular chains undergo elongation under tension, leading to a reduction in the stability of their geometric structure, thereby impacting their mechanical and electrical properties. Furthermore, at higher electric field intensities, there is a decrease in the front orbital energy gap accompanied by an increase in conductivity. Simultaneously, there is a shift in active sites for molecular chain reactions and the formation of energy level distribution for hole traps and electron traps along the front track of molecular chains, making it easier for FEPM to capture injected space charges. When reaching a critical value of 14.6547 V/nm, the molecular structure of FEPM undergoes destruction with significant changes observed in its infrared spectrum. It offers theoretical backing for the direction of material modification, high voltage breakdown testing, and assessment of the insulation state.

Graphical abstract