# Effects of Organic Acidic Products from Discharge-Induced Decomposition of the FRP Matrix on ECR Glass Fibers in Composite Insulators

## TL;DR

This study explores how organic acids from decomposed polymer matrices damage glass fibers in composite insulators under electrical discharge conditions.

## Contribution

The study identifies organic acids, especially carboxylic acids, as a key factor in the deterioration of ECR glass fibers under partial discharge conditions.

## Key findings

- Organic acids from FRP matrix degradation are formed via hydrolysis of anhydrides under partial discharge conditions.
- Carboxylic acids cause more severe damage to ECR glass fibers than inorganic acids by degrading coupling agents and reacting with silica networks.
- High temperatures accelerate the deterioration of glass fibers caused by organic acids.

## Abstract

This study investigates the degradation mechanisms of fiber-reinforced polymer (FRP) matrices in composite insulators under partial discharge (PD) conditions. The degradation products may further cause deterioration of the electrical and chemical resistance (ECR) glass fibers. Using pyrolysis–gas chromatography-mass spectrometry (PY-GC-MS) and high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS-MS), the thermal degradation gas and liquid products of the degraded FRP matrix were analyzed, revealing the presence of organic acids. These acids form when the epoxy resin’s cross-linked bonds break at high temperatures, generating anhydrides that hydrolyze into carboxylic acids in the presence of moisture. The hydrolyzation process is accelerated by hydroxyl radicals produced during PD. The resulting carboxylic acids deteriorate the glass fibers within the FRP matrix by degrading surface coupling agents and reacting with the alkali metal–silica network, leading to the substitution and precipitation of metal ions. Organic acids, particularly carboxylic acids, were found to have a more severe deteriorating effect on glass fibers compared to inorganic acids, with high temperatures exacerbating this process. These findings provide critical insights into the deterioration mechanisms of FRP under operational conditions, offering valuable guidance for optimizing manufacturing processes and enhancing the longevity of composite insulators.