Quantitative evaluation of interfacial adhesion between fiber and resin in carbon fiber/epoxy composite cured by semiconductor microwave device

Interfacial adhesion between carbon fiber (CF) and epoxy resin in carbon fiber-reinforced epoxy composite, which was prepared by different heating process such as semiconductor microwave (MW) device and conventional electric oven, has been evaluated quantitatively. The interfacial shear strength (IFSS) between CF and epoxy resin, which was an indicator of adhesion on the interface, was measured by a single fiber fragmentation test. The single fiber fragmentation test showed that the IFSSs of the prepared specimens were different by heating methods. In the case of MW process, the curing reaction of epoxy resin on the CF interface would be progressed preferentially due to the selective heating of CF, resulting that the IFSSs of specimens prepared by MW irradiation were increased by enhancing the output power of MW. However, the IFSSs of the specimens were decreased by excessively high output power because the matrix resin on the CF interface was thermally degraded. As results, by optimizing the MW conditions of output power and irradiation time, the IFSS of the sample cured by MW was increased by 21% as compared to oven-heated one. It was found that the interfacial adhesion between CF and epoxy resin would be improved by the MW-assisted curing reaction on the surface of CF.