Influence of seawater absorption on the vibration damping characteristics and fracture behaviors of basalt/CNT/epoxy multiscale composites

In the present study, the effect of seawater absorption on the damping and fracture behaviors of carbon nanotube (CNT)-modified epoxy/basalt fiber (basalt/CNT/epoxy) multiscale composites was investigated. Forced vibration of a cantilever beam and fracture tests were performed using dry and seawater-saturated basalt/CNT/epoxy multiscale composites. The results showed that the vibration damping coefficient is increased approximately 50% by seawater absorption; the fracture behavior of basalt/CNT/epoxy multiscale composites was also significantly affected. Compliance of the seawater-saturated samples was increased and fracture load was decreased compared to the dry samples. The average fracture toughness of seawater-saturated samples was approximately 20% lower than that of dry samples. SEM examination of the fracture surfaces revealed that the decreased fracture toughness of the seawater-saturated samples was due to the weakening of interfacial bonding from swelling of the epoxy matrix. This observation is crucial when the composites are used as marine structures such as hull of the ship, and propeller.