Carbon Fiber Reinforced Plastics (CFRP) are expected to be used for the structural parts of automobiles and aircraft because of their light weight and superior mechanical properties. Since the mechanical properties of CFRP are affected by the interfacial properties of the reinforcing fiber and matrix, it is necessary to control their interfacial properties. The CF/matrix interfacial properties are reported to be improved by grafting carbon nanotubes (CNT) on carbon fibers. When CNTs are grafted at high temperature, however, the strength of the carbon fiber itself is reported to be decreased. We have been developing the CNT grafting technology using Ni as the catalyst that enables CNT grafting at low temperature. However, the effects of CNT deposition length and deposition density on the interfacial properties of CF/matrix have not been clarified. In this study, the influence of CNT deposition length and deposition density on the interfacial properties of CNT grafting carbon fiber/matrix was evaluated by single fiber pull-out tests. The longer the Ni plating time became, the more the density of Ni particles on carbon fiber became and higher interfacial share strength of CF/matrix was obtained. Also, the longer the grafting time became, the longer CNT grew and resulting higher interfacial share strength of CF/matrix was obtained.
