Study on electrical properties of micro-nano structured epoxy composites

Abstract

With the aim of reducing the insulation faults in GIS and achieving the purpose of GIS device miniaturization, it is very important to develop a new type insulation material. In this paper, the micro-nano AI203/Epoxy composites were proposed, and its dielectric breakdown strength was investigated. Nano-fillers and micro-fillers (u-AI203 with a purity of 99.9%, particle size range at 12-21 J.lm for micro fillers, and average particle size with 30 nm for nano fillers)were dispersed in the epoxy resin with shear force and ultrasonic vibration. The specimens were produced by a curing reaction with the hardener. Six kinds of material were prepared for this investigation, which were neat epoxy, nano-composite (loaded with 5 wt% nano-Al203 fillers), nano-composite (loaded with 5 wt% nano-Ti02 fillers),micro-composite (loaded with 65 wt% micro-Al203 fillers), nano-micro-mixture-composites (loaded with 2 wt% nano-Al203 fillers and 63 wt% micro-Al203 fillers), nano-micro-mixture-composites (loaded with 2 wt% nano-Ti02 fillers and 63 wt% micro-Al203 fillers).Dispersion of the micro and nano AI203 in the epoxy resin was observed through SEM, and thermal behavior was analyzed with Thermo-Gravimetric Analysis (TGA) and differential scanning calorimeter (DSC). The dielectric constant and dielectric loss were measured by broadband dielectric spectrum test facility. Dielectric breakdown experiments were carried out through the sphere-plate sample-sphere configuration under AC voltage.

Characteristics of Gel Time and Dielectric Strength of Epoxy Composite According to the Mixing Ratio of Micro-Fillers

“…As the content of SiO 2 micro-filler decreases, covalent bonding by -OH groups present on the surface of the SiO 2 molecule decreases, thereby reducing the interfacial bonding strength at the surface of the epoxy micro-composite [30][31][32]. Therefore, the relative permittivity increased and the dielectric loss tangent decreased as the mixing ratio of the SiO 2 in the epoxy micro-composite decreased.…”