Effect of fiber surface functionalization on shear behavior at carbon fiber/epoxy interface through molecular dynamics analysis

Different functional group densities of carbon fiber surface were achieved by changing surface treatment duration. Dynamic adsorption and shear behavior at the interface between epoxy resin and carbon fibers were analyzed in this study through molecular dynamics analysis and microscopic verification test. The results suggested that oxygen atoms of the functional group at the end of the epoxy matrix first accumulate on the carbon fiber surface, and then the whole molecular chain is driven towards the carbon fiber surface. It was found that more functional groups are accumulated at the surface and the interfacial shear strength increase with the extension of the acid treatment time. After 60 min of acid treatment, the interfacial shear energy from the simulation increased by 41.1% while the shear strength increased by 29.9%. The good consistence between the experimental and simulation results indicates that the approach proposed in this work could provide a method to study the interfacial properties of fiber reinforced polymer (FRP).