Thermal Degradation Investigation of Glass Fiber Reinforced Polymer used in High Voltage Composite Insulator Core

The abnormal heating of high voltage composite insulator seriously affects the safe and stable operation of the overhead transmission line. In order to understand and avoid such accidents, the thermal degradation behavior of glass fiber reinforced polymer (GFRP) core deserves special attention. In the present work, the thermogravimetric analysis (TGA) was used to simulate the thermal degradation process of GFRP materials. The non-oxidative environment (nitrogen) and oxidative environment (air) were both used for comparing the difference of thermal degradation of GFRP in these conditions. The changes of GFRP during the thermal degradation process were characterized from both chemical composition and micro physical structure points of view by using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). By comparing the final residues of GFRP after thermal degradation in nitrogen and in air up to 800 °C, it was found that the chemical reactions during thermal degradation of GFRP contains auto-oxidation, aliphatic structure scission and formation of polyaromatic. Based on the results, the entire process of thermal degradation of GFRP from initial intact to final deterioration was characterized, the present work is helpful for better understanding of the thermal degradation behavior of GFRP used in high voltage composite insulator as well as in other industry applications involving the temperature rising condition.