Molecular dynamics simulation of the interface properties of continuous carbon fiber/ polyimide composites

The resin-fiber interface is pivotal to the performance of composites. Molecular dynamics simulations were used to study the relationship between interface structure and interface mechanical properties of carbon fiber/polyimide composites. The rationality of the models and the polymer consistent force field were verified by the glass transition temperature, the density of polyimide and the pull-out test. It was found that the interfacial shear strength (IFSS) with grafted functional groups was greatly intensified with the order of -C6H5 > -COOH > -CH3 > -OH > -NH2. The IFSS increased linearly with the increasing number of grafted groups. Grafted polyimide monomers can intensify interfacial performance more effectively. We also calculated the interaction energy by density functional theory method and the surface roughness to reveal the enhancement mechanism of the interface, which is the synergistic effect of the non-bond interaction and surface roughness.