Modulation of Epoxy Polymer Trapping Energy Levels by Fluorinated Diluents to Improve Insulation Properties

The lightweight and miniaturized design of power equipment, as well as their extreme operating environments, are placing higher demands on the insulation properties of epoxy polymers (EPs), which are closely related to the space charge distribution. To further homogenize the electric field distribution and improve the insulating properties of EPs, this article improved the space charge migration rate of EPs by providing sp ³ molecular hybridization orbitals with fluorine-modified butyl glycidyl ether (BGE) diluent. Three EPs, BGE/EP, 3F-BGE/EP, and 7F-BGE/EP, were prepared, and density functional theory (DFT) calculations showed that fluorinated 3F-BGE and 7F-BGE provided sp ³ hybridized orbitals for the EP system in the trap energy range, which reduced the trap energy levels from 2.76 to 2.42 and 1.65 eV, respectively, and improved the space charge migration rate. The surface potential decay test of the EPs revealed that when the applied voltage was stopped for 3000 s, the surface potentials of 3F-BGE/EP and 7F-BGE/EP decreased by 11.33% and 16.67%, respectively, and the flashover voltages along the surface increased by 7.06% and 17.98%, respectively, with no decrease in resistivity compared to BGE/EP. This method increased the space charge migration rate and insulation properties of the EP without decreasing its resistivity.