The effects of string‐like copper plated short carbon fibers reinforced rigid polyurethane composites

Abstract The performance of short carbon fibers (CFs) reinforced rigid polyurethane (RPU) composites is largely restricted by poor interfacial strength and damage‐tolerance. In order to optimize the performance of CFs/RPU composites, we prepared CFs with a new structure starting from the modified CFs morphology. In this paper, a new type of fiber morphology, which was string‐like copper‐plated CFs (string‐like Cu‐CFs) were prepared by the electrodeposition method. The structure of the string copper could increase the contact area of the CFs and the RPU matrix and mechanical interlocking. At the same time, the surface roughness of the CFs could be enhanced, thereby promoting the formation of irregular interfaces. Ordinary CFs composite materials showed the low strength and toughness, due to the more stress concentrations generated around the fiber ends. By adding string‐like Cu‐CFs into the RPU matrix, the pinning effect was achieved due to the special fiber structure, which improved the strength and toughness of the string‐like Cu‐CFs/RPU. Compared with pure RPU, the tensile strength, bending strength, and impact strength of string‐like Cu‐CFs/RPU composites were improved by 15.3, 148.3, and 171.4%, respectively. At the same time, the string‐like Cu‐CFs formed a more continuous conductive network inside the RPU matrix, which significantly improved the electrical conductivity of the composites.