Durability of glass‐fiber‐reinforced polymer composites in an alkaline environment

This study investigated the aging of urethane and urethane‐modified vinyl ester (UMVE) GFRPs (glass fiber reinforced polymers) when they were exposed to alkaline solution for six months under a sustained load of 34.5 MPa or 16–20% of their tensile strength. The second experiment exposed both types of GFRP to alkaline solution without load for 6 months. The final experiment determined the alkaline solution diffusion coefficients into GFRP and neat polymer resin samples by measuring the change in mass of each sample as a function of time. After the GFRP samples were aged for 6 months, their tensile strengths were measured and compared with that of non‐aged samples to determine the aging effect. It was found that alkaline solution alone without sustained load did not significantly reduce or change the tensile strength of any GFRP sample. However, the presence of sustained load greatly increased the aging effect, particularly more for urethane GFRP than on UMVE GFRP. Urethane GFRP experienced a tensile strength reduction of 57.5%, while UMVE GFRP lost 27.3% of its original tensile strength. J. VINYL ADDIT. TECHNOL., 13:221–228, 2007. © 2007 Society of Plastics Engineers