Modeling of the effect of water ingress on the bond between carbon fiber – Epoxy resin with the molecular dynamics technique

FRP (fiber reinforced polymer) has taken advantages of the fiber reinforcement and resin matrix, possessing excellent mechanical properties and corrosive resistances, even in harsh environments. The lack of the knowledge of the durability performances of FRPs in various environmental conditions and the related degradation mechanisms of FRPs leads to significantly conservative design. Water ingress plays a critical effect on the durability of FRP, due to susceptibility of the bond between the fibers and resin matrices. In the present paper, molecular dynamics technique was used to model the moisture effect on the fiber-resin bond. The bonding performances of the epoxy on carbon fibers under dry and wet conditions were simulated. Free energy profiles were calculated to quantify interfacial adhesion. As shown from the decline of binding free energy, the water ingress led to remarkable deterioration of the fiber bonding to the resin matrix. The study is expected to be helpful for both the development of durable FRPs, and to predict the service life of a FRP subjected to hydrothermal aging accurately.