Study of seawater effect on the mechanical and thermomechanical properties of hybrid multiwall carbon nanotube/graphene nanoplatelet‐glass fiber/epoxy laminates

Abstract The influence of seawater aging on the flexural and thermomechanical properties of glass fiber/epoxy (GF/E) composites containing the hybrid combination of multiwall carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) was experimentally investigated in this work. The three‐point bending and dynamic mechanical analysis were performed to test flexural modulus, flexural strength, strain to failure, storage modulus, and glass transition temperature (T_g) of hybrid MWCNT/GNP‐GF/E composites at different mixing ratios (1:0, 7:1, 3:1, and 0:1) which were immersed in seawater at 60°C. The results confirm that seawater aging plays a significant role in reducing the mechanical and thermomechanical properties of hierarchical composite laminates due to degradation and weakening of the fiber/matrix interface as a consequence of plasticization and swelling effects of the polymer matrix. Despite this serious physical degradation, MWCNT/GNP‐GF/E hybrid composites with (7:1) showed a better resistance to seawater aging, with slight improvements in flexural strength (2%), strain to failure (14%), and T_g (12%) compared to neat GF/E composites, due to positive synergistic effect of the carbon nanostructures in the composite laminates, making them suitable for marine applications.