# Study on the Effect of the Nucleophilicity of Amine Accelerators on the Process and Dielectric Properties of Epoxy Materials for Dry Bushing

## TL;DR

This study examines how the nucleophilicity of amine accelerators affects the processing and dielectric properties of epoxy materials used in dry bushings.

## Contribution

The paper reveals the trade-off between processing performance and dielectric properties caused by varying nucleophilicity of amine accelerators in epoxy materials.

## Key findings

- Stronger nucleophilicity reduces gel time and increases exothermic temperature rise, worsening processing performance.
- Strong nucleophilicity improves dielectric properties, reducing dielectric loss by 39.5% and increasing breakdown strength by 11.4%.
- TEA shows 50% shorter gel time and 55.3% higher exothermic temperature rise compared to DET.

## Abstract

The impregnation and curing process of dry bushing requires the epoxy material for bushing to have a good process performance. In addition, the actual operating conditions of dry bushing put forward high requirements on the dielectric properties of the epoxy material. Amine accelerators can not only improve the technological properties of epoxy materials such as gel time and curing exothermic temperature rise by regulating the reaction rate of epoxy resin and anhydride curing agent, but also optimize the dielectric properties of epoxy materials by regulating the crosslinking density of epoxy materials. However, there are many types of amine accelerators, and the effects of amine accelerators with different nucleophilicity on epoxy materials vary greatly. In this paper, four kinds of amine accelerators with different nucleophilic ability were selected to study the influence of the nucleophilic ability of amine accelerators on the process and dielectric properties of epoxy materials. The results show that the stronger the nucleophilicity of the amine accelerator, the shorter the gel time of the epoxy mixture and the higher the exothermic temperature rise during curing, indicating a poorer processing performance. However, stronger nucleophilicity also endows the epoxy material with superior dielectric properties. Among them, the strong nucleophilic ability of TEA shortens the gel time of the material by 50% and increases the curing exothermic temperature rise by 55.3% compared with the weak nucleophilic ability of the DET epoxy system; the dielectric constant and dielectric loss of the material are reduced by 8.3% and 39.5%, respectively, and the breakdown strength is improved by 11.4%. This paper reveals the contradictory relationship between the process and dielectric performance of epoxy materials triggered by the difference in the nucleophilic ability of amine accelerators, and it also provides a new research idea for the improvement of the process and in the dielectric performance of epoxy materials for dry bushing.