Long-term deterioration of GFRP in water and moist environment

This report examines the effects of water and moisture on the durability of pultruded glass-fiber-reinforced polymers (GFRP) with vinylester resin for applications in normal air conditions. Deterioration tests, including both immersion and atmosphere conditions at various temperatures, were conducted to investigate the deterioration characteristics of pultruded GFRP after being permeated by water. The main findings from the tests were that cracks appeared on the surface of the GFRP and that the weight of the materials decreased, which may be attributed in the surface treatment oil for the glass-fiber cloth being dissolved away. The bending strength of the GFRP was also found to be reduced. The rate of weight decrease and the reductions in bending strength were greater in a 60 degreesC water-immersion condition compared to both a 60 degreesC moist-atmosphere condition and a 40 degreesC water-immersion condition. This difference is due to the fact that the glass fiber and matrix resin separated in water at 60 degreesC. Although the matrix resin changed color in air at 60 degreesC, becoming noticeably brown, no chemical changes were found by infrared spectra.