Effect of Space Charge Density and High Voltage Breakdown of Surface Modified Alumina Reinforced Epoxy Composites

Abstract

The incorporation of 90 nm alumina particles into an epoxy matrix to form a composite microstructure is described in present study. It is shown that the use of ultrafine particles results in a substantial change in the behavior of the composite, which can be traced to the mitigation of internal charges when a comparison is made with conventional <TEX>$Al_2O_3$</TEX> fillers. A variety of diagnostic techniques have been used to augment pulsed electro-acoustic space charge measurement to provide a basis for understanding the underlying physics of the phenomenon. It would appear that, when the size of the inclusions becomes small enough, they act cooperatively with the host structure and cease to exhibit interfacial properties. It is postulated that the <TEX>$Al_2O_3$</TEX> particles are surrounded by high charge concentrations. Since <TEX>$Al_2O_3$</TEX> particles have very high specific areas, these regions allow limited charge percolation through <TEX>$Al_2O_3$</TEX> filled dielectrics. The practical consequences of this have also been explored in terms of the electric strength exhibited. It would appear that there was a window in which real advantages accumulated from the nano-formulated material. An optimum filler loading of about 0.5 wt.% was indicated.