Characterization of Thermal Degradation of Glass Fiber Reinforced Polymer Used in High Voltage Composite Insulator in Nitrogen Atmosphere by FTIR and Micro-Morphology Analyses

The thermal degradation behavior of glass fiber reinforced polymer (GFRP) in nitrogen atmosphere was studied in the present work by thermogravimetric analysis (TGA). 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). The steps of thermal degradation of GFRP in nitrogen were investigated in detail by analyzing the residues at different set temperatures, then the temperature ranges for the disappearance of methyl and aliphatic structure and the appearance of carbonyl and polyaromatic structure were determined with a temperature resolution of 20 °C. The changes of micro physical structure of GFRP during the thermal degradation in nitrogen involved the softening, melt, shrinkage, appearing of twisted and shrink lines, debonding of interface between glass fiber and epoxy resin matrix and releasing the pyrolyzed gas consecutively. Based on the results, the entire process of thermal degradation of GFRP from initial intact to final deterioration in nitrogen up to 800 °C 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.