Enhancing the insulation performance of aramid fiber epoxy resin by constructing a polar-nanofibrillation structure on the fiber surface

Aramid fiber, as a new generation of synthetic fiber material, has excellent insulation and mechanical properties and is widely used in high-voltage power transmission and transformation equipment. However, the problems of smooth surface and low chemical reactivity seriously restrict the combination with polymers and reduce the withstand voltage characteristics of insulation devices. Hence, this paper proposes to use aramid nanofibers (ANFs) obtained through nanofibrillation treatment to regulate the surface roughness of aramid fibers. Meanwhile, polar functional groups were introduced during the deprotonation process, successfully constructing polar-nanofibrillation structures on the aramid fiber surface, further regulating the polarity of fiber surfaces. Through insulation performance tests and molecular dynamics simulations, the influence of polar functional group types on the insulation performance of aramid fiber-epoxy resin composites was revealed. The results show that the flashover voltage of the modified AFEP has increased by 58.01% and the breakdown field strength has increased by 56.52%. Analysis suggests that different polarity treatments have different mechanisms for enhancing insulation performance. Among them, the amino group is achieved by enhancing the interface bonding between aramid fibers and epoxy resin, while the fluorine-containing groups improve the material’s ability to control charge distribution.