Multifunctional epoxy/carbon composites with a fully reparable interface

In this work, for the first time, carbon fibers (CFs) were coated with nanosized-polycaprolactone (PCL) particles to obtain a functionalized self-healable interphase, capable to fully recover the pristine interfacial shear strength with a debonded epoxy matrix. PCL nanoparticles were initially water-dispersed at different concentrations and deposited on CFs by electrophoretic deposition. The application of various voltage levels resulted in different morphologies of the coating. Epoxy microdroplets were deposited and cured on neat and PCL-coated fibers. After complete interfacial debonding by microdebonding tests, an electric current was applied on CFs to activate a thermal interfacial healing by Joule effect. The healing efficiency was estimated as the ratio of interfacial shear strength measured before and after healing. An outstanding repairing efficiency was obtained upon thermal mending with a complete recovery of the original interfacial shear strength, thus indicating a strong potential of the PCL nanocoating as interfacial healing agent for composite structures.