Dielectric and Insulation Properties of Polyimide-based Boehmite Nanocomposite Material

Abstract

In recent years, small and medium size generators are used as engine generators. The authors aim to develop enamelled wire that exceeds conventional resin insulation lifetime. Among nanocomposite materials, boehmite-based materials are reported to have a longer lifetime than silica-based materials, and they are expected as new insulating materials for enamel wire insulation layer. In this paper, we report on the effect of boehmite filler on dielectric properties and AC conductivity by acquiring complex permittivity and AC conductivity of a film sample with nano-boehmite alumina added to polyimide resin compared with those of samples with silica nano-fillers and without nano-fillers. As a result, it is suggested that the ionic carrier is more likely to move in the polyimide sample with AIOOH filler than in the neat sample in the high temperature region of 180 °C. From the above results, it is considered that the conductivity and the relative permittivity increase in the high temperature and low frequency region are due to the influence of crystal water of boehmite. In addition, measurements of life time of enamel twisted pair samples coated with polyimide filled with boehmite alumina nano-filliers were also made with comparison to that of samples without the boehmite alumina fillers.