Influence of Elevated Temperature on the Mechanical and Microstructural Properties of Glass Fiber-Reinforced Polymers

Abstract

Glass fiber-reinforced polymers (GFRPs) have attracted significant attention as structural materials because of their high fatigue resistance, corrosion resistance, strength, and stiffness. This study examined the effect of elevated temperatures (150, 250, 350, and 450oC) on the microstructural and mechanical properties of GFRP plates. The number of bubbles increased as the firing temperature increased, and the bubbles burst at 250oC or higher, forming pores on the surface. A tensile test was conducted, and the maximum stress of the GFRP plates fired at 150, 250, and 350oC was reduced from 54.2 to 52.2, 40.3, and 24.0 MPa, respectively, compared to that of the unfired GFRP plate. Meanwhile, the elastic moduli of the GFRP plates fired at 150, 250, and 350oC reduced from 19.1 to 18.3, 16.1, and 12.1 GPa, respectively, compared to that of the unfired GFRP plate. This reduction in the mechanical properties of the GFRP plates at elevated temperatures was attributed to the degradation of the mechanical properties of the resin matrix due to glass transition and decomposition, debonding, and an increase in surface defects. The maximum strain decreased gradually with increasing firing temperature, suggesting that the brittleness of the GFRP plates increased at elevated temperatures.