Water absorption and hydrothermal ageing of epoxy adhesives reinforced with amino-functionalized graphene oxide nanoparticles

The study is focused on quantitative characterization of water absorption and hydrothermal ageing effects in a room-temperature amine cured epoxy adhesive widely used in automotive, aerospace, construction, and marine industries. Amino-functionalized graphene oxide (mGO) nanoparticles were incorporated into the epoxy (up to 1.72 wt.%) enabled cross-linking reactions and providing high interfacial adhesion, superior reinforcement efficiency and enhanced resistance to hydrothermal ageing of nanocomposites. Anomalous water absorption accompanied by progressive weight loss of samples (down to 7%) is fitted by two-stage models considering additive and coupled contribution from water diffusion and leaching of low molecular weight epoxy species. Nanocomposites are characterized by lower water diffusivity (40%) and decreased leaching effects (70%). High reinforcing efficiency of epoxy/mGO appeared in the increased glassy and rubbery storage moduli (60%), glass transition temperature (10 °C) and activation energy of glass transition (70%) compared to the neat epoxy. Hydrothermal ageing resulted in noticeable properties degradation of samples, although to a much lower extent in the case of nanocomposites. The results will contribute to the enhancement of global durability of common epoxy-based adhesives and extension of their lifetime.