Mechanical durability of marine-grade glass fiber-reinforced polymer composites exposed to accelerated hygrothermal aging in seawater

This study examines the effects of hygrothermal aging on the mechanical properties of glass fiber-reinforced polymer composites (GFRPCs) in marine environment. Composites with 55%, 60%, and 65% glass fiber content were fabricated using vacuum-assisted resin infusion and microwave curing, which enhances production efficiency and mechanical properties. Accelerated cyclic temperature aging was simulated by immersing the samples in seawater between approximately 20°C and 75°C. A series of mechanical tests, including compression, flexural, impact, and fracture toughness, were performed on both hygrothermally aged and as-manufactured (unaged) samples. Furthermore, to evaluate the viscoelastic behavior of the composite across a temperature range of 20°C–160°C, the dynamic mechanical analysis (DMA) test was conducted. Hygrothermal aging caused notable property degradation, with reductions in compressive, flexural, impact strength, and fracture toughness by 26%, 25%, 29%, and 28%, respectively, for composites with 55% fiber content. Composites with 65% fiber content showed better resistance to degradation. Moisture-induced resin plasticization, fiber-matrix interface failure, and micro-cracking were identified as the primary mechanisms of deterioration, confirmed by scanning electron microscopy. These results emphasize enhancing matrix stability and fiber-matrix bonding to improve the durability of GFRPCs in marine environments.