Dielectric properties of epoxy/alumina nanocomposite influenced by control of micrometric agglomerates

Introduction of metal oxide nanoparticles to polymer material is known to have unique dielectric behavior and significant advantages in electrical insulation performance in power apparatus. This paper presents an attempt to clarify the influence of dispersibility of nanoparticles, especially focusing on agglomerates, on dielectric properties of a nanocomposite system by changing particle dispersion processes. Experiments were carried out in epoxy/alumina nanocomposites with the particle dispersion techniques by applying ultrasonic wave and centrifugal force. For the dispersibility control of nanoparticles, we changed the duration of ultrasonic wave and centrifugal force. The experimental results clarified the effect of centrifugal force on the separation of agglomerates and the effect of ultrasonic wave on the disruption of agglomerates. Next, we examined the dielectric properties such as relative permittivity and tan δ of the nanocomposites. As the result, we verified that the permittivity of epoxy/alumina nanocomposites became low due to separation and disruption effects of the agglomerates.