Effects of seawater immersion on water absorption and mechanical properties of GFRP composites

Water absorption behavior and mechanical properties of specimens of an epoxy resin casting and the glass fiber reinforced epoxy matrix composites (GFRP) with two fiber volume fractions (Vf) immersed into artificial seawater were investigated. The composite specimens absorbed less water than the resin casting because water absorption by the matrices was the main way in the composites. The composites with a Vf of 44% absorbed more water than the composites with a Vf of 34% because there were more micropores inside the fiber bundles and capillary paths in the higher fiber volume fractions. Due to the reversible and irreversible changes in the resin casting and the failure of the fiber/matrix interface, the tensile strength, the flexural strength, and the ILSS of the composite specimens after 42 days’ immersion decreased 13%, 43%, 50%, respectively. And the tensile strength, the flexural strength and the ILSS of the specimens after desorption were 97%, 38%, and 43% of the original state, respectively.