Effect of water immersion on shear strength of epoxy adhesive filled with graphene nanoplatelets

Adhesive bonds are frequently used in industries such as aerospace, automotive, and civil engineering due to their ability to reduce damage to the adherend and their lightweight. However, their application is restricted by their inadequate durability and reliability in hostile environments. Graphene nanoplatelets (GNPs) are employed to enhance epoxy adhesives in this article. The thick adherend shear test is utilized to examine how the shear properties change with different water ageing times. Before exposure to water ageing conditions, GNP-reinforced adhesives exhibit a 3.51% increase compared with neat epoxy at a GNP content of 0.25 wt%. However, after 56 days of water ageing, the increase in shear strength is found to be 13.79%. This suggests that the well-dispersed GNP can reduce the degradation rate in shear properties by half, from 16.71 to 8.44%, at a GNP content of 0.25 wt%. Additionally, as water ageing time increases, the positive influence of GNP on shear properties becomes more evident. The addition of GNP delays the degradation of shear properties caused by water ageing conditions. The effect of GNP does not improve with higher GNP content. When the GNP contents increase to 1 wt%, the shear strength of the GNP-reinforced adhesive decreases compared to neat epoxy.