Fracture behavior of an alumina/epoxy resin interface and effect of water molecules by using molecular dynamics with reaction force field (ReaxFF)

As transport vehicles, such as automobiles and aircraft, have become lighter and more efficiently, the use of resins to bond dissimilar materials has significantly increased. However, a natural oxide film and an hydroxide film are formed on metal surfaces, which alters adhesion characteristics. Sometimes, degradation of adhesion is accelerated by water molecules at the interface. Its mechanism is still not clear. In this study, the interface between a metal and resin was modeled by molecular dynamics (MD) simulation. Reaction force field (ReaxFF) was employed for MD simulations to investigate the effect of interfacial surface moisture (water molecules) on adhesion. The amount of water molecules at the interface was varied, and the effect of water molecules on adhesive strength under uniaxial tensile loading was investigated. In addition, the potential energy around the interface was calculated, and the adhesion mechanism with respect to water molecules was carefully discussed.