Analytical Model for the Transient Permittivity of Uncured TiO2 Whisker/Liquid Silicone Rubber Composites Under an AC Electric Field

TL;DR

This paper presents an analytical model to predict the transient permittivity of uncured TiO2 whisker/liquid silicone rubber composites under AC electric fields, aiding the design of insulation devices with adaptive permittivity gradients.

Contribution

An efficient analytical model based on optical imaging and dielectric monitoring for predicting transient permittivity in uncured composites, surpassing complex electrodynamics calculations.

Findings

Model accurately predicts transient permittivity changes.

Filler content and electric field strength influence the transient process.

Applicable to various low-viscosity uncured composites with multiple fillers.

Abstract

The electric field grading of dielectric permittivity gradient devices is an effective way of enhancing their insulation properties. The in-situ electric field-driven assembly is an advanced method for the fabrication of insulation devices with adaptive permittivity gradients, however, there is no theoretical guidance for design. In this work, an analytical model with a time constant is developed to determine the transient permittivity of uncured composites under an applied AC electric field. This model is based on optical image and dielectric permittivity monitoring, which avoids the direct processing of complex electrodynamics. For a composite with given components, the increased filler content and electric field strength can accelerate the transient process. Compared with the finite element method (FEM) based on differential equations, this statistical model is simple but efficient, and can be applied to any low-viscosity uncured composites, which may contain multiple fillers. More importantly, when a voltage is applied to an uncured composite insulating device, the proposed model can be used to analyse the spatiotemporal permittivity characteristics of this device and optimise its permittivity gradient for electric field grading.