Improving the interfacial property of carbon fiber/vinyl ester resin composite by grafting modification of sizing agent on carbon fiber surface

The poor interfacial adhesion between carbon fibers (CFs) and vinyl ester resin (VE) has seriously hampered the application of CFs/VE composites. In this work, the interfacial adhesion was efficiently enhanced by grafting acrylamide with epoxy sizing agent on CFs surface. The grafting reaction was feasible according to the thermodynamic calculation. The optimal grafting condition was 80 °C for 10 min based on the kinetic investigation by differential scanning calorimeter. Surface morphology and surface composition of modified carbon fibers (MCFs) were characterized, which indicated that acrylamide was grafted successfully on CFs surface and the surface roughness was increased slightly. After grafting, the interface shear strength of MCFs/VE composites was significantly improved by 86.96% and the interlaminar shear strength was enhanced by 55.61% due to the covalent bonds in interphase and the toughening effect of sizing gent. Moreover, the static and dynamic mechanical properties of composites with different interfacial adhesion were measured, which further confirmed the effect of the grafting modification.