EFFECT OF TEMPERATURE AND SEAWATER EXPOSURE ON GLASS/POLYURETHANE COMPOSITE: EXPERIMENTAL AND FAILURE ANALYSIS

The lack of durability is the major issue faced by polymers and their composites for saline water exposure. The experimental investigation of seawater exposure of Fiber reinforced polymer (FRP) composite is limited to a short period of time. Also, this small range of data was used in the development of the prediction model. The present paper reports a long-term experimental investigation and prediction of the durability of FRP composites exposed to seawater at different temperatures. E-glass/polyurethane samples were exposed to 23 °C, 45 °C and 65 °C seawater for up to 2700 days (90 months). Tensile tests evaluated the mechanical performance of the composite as a function of exposure time, and a strength-based technique was used to assess the durability. The experimental results revealed that the tensile strength of the composite reduced by 37.6% and 63.6% after immersion of 90 months in seawater at 23 and 65 °C, respectively. The prolonged immersion in seawater results in plasticization and swelling in the composite material, which accelerates the fiber/matrix debonding. Failure analysis was performed to investigate the failure mode of the samples. SEM micrographs indicate fiber/matrix debonding, potholing, fiber pull-out, river line marks, and matrix cracking which indicates deterioration in the tensile properties of the composites.