Seawater Aged Basalt/Epoxy Composites: Improved Bearing Performance with Halloysite Nanotube Reinforcement

Abstract

Although they enable for facile disassembly and inspection of critical assemblies, bolted joints are common damage initiation sites in laminated composite structures. Sudden failure can occur at these locations especially with the combination of corrosive environments. In order to well understand and characterize for marine applications, we aimed to research the impact of seawater aging and halloysite nanotube (HNT) nano reinforcements on the bearing performance of basalt-epoxy composites. For this, basalt fabrics were impregnated with HNT modified epoxy matrix via vacuum infusion and the resultant multi-scale laminates submerged in seawater up to 6 months after assembling via bolted joints. Single shear tensile tests of seawater aged joints were performed according to ASTM D5961 and the results compared with the HNTs reinforced hybrid laminates. HNTs nano reinforcements remarkably improved the bearing strength basalt/epoxy composite laminates with a 18% increase. In addition, seawater aging drastically impairs the bearing response of composite laminates with an almost 45% reduction in bearing strength after 6 months of exposure. Bearing fracture modes were also affected with the addition of HNTs and seawater aging, the resultant fracture surfaces were examined to reveal degradation mechanisms related to seawater aging and HNTs reinforcement after single shear tensile tests. The results can contribute to a better understanding of mechanical design parameters for bolted fiber reinforced polymer composites exposed to corrosive environments.