The effect of graphene nanoplatelets on the flexural properties of fiber metal laminates under marine environmental conditions

Abstract

In this research, the effects of adding graphene nanoplatelets (GNPs) on the flexural properties of fiber metal laminates (FMLs) under marine environmental conditions were investigated. The FMLs were fabricated with alternating layers of Al6061 and glass fiber reinforced epoxy (GFRE) with different concentrations of GNPs (0.25, 0.5, and 1.0 wt%). The samples were immersed in the 3.5 wt% NaCl solution for different immersion times (7, 14, and 28 days) at room temperature. The addition of GNPs led to decreasing the water absorption of samples after immersion in the 3.5 wt% NaCl solution; the lowest absorbed water was for the samples with 0.25 wt% GNPs. Although the flexural properties of samples decreased by increasing the immersion time, the lowest reduction in flexural properties was obtained for the sample with 0.25 wt% GNPs. Results showed that by adding GNPs and immersing the specimens in the 3.5 wt% NaCl solution for 28 days, the flexural strength and modulus, and strain values of specimens containing 0.25 wt% GNPs were respectively about 128%, 63%, and 1.85 times higher than those of samples without GNPs. Also, the reduction of the flexural properties caused by immersion in NaCl solution was lower than that of samples without GNPs. Moreover, the water uptake of samples with 0.25, 0.5, and 1.0 wt% GNPs was about 38%, 31%, and 37% lower than that of samples without GNPs after 28 days of immersion. Microstructural analyses revealed that the improvements in the metal/polymer adhesion and mechanical properties of the polymeric part of FMLs resulting from various mechanisms were the main reasons for the improved performance of samples with GNPs under marine conditions.