EVALUATION OF BONDING STRENGTH OF SURFACE-OXIDIZED CARBON FIBER

摘要

PURPOSE:To evaluate easily the degree of oxidation of surface-oxidized carbon fiber, namely, the bonding strength to a matrix resin and to thereby make it possible to expedite and simplify the control of a process for producing a composite material, by immersing said carbon fiber in an electrolyte solution and measuring its differential capacity. CONSTITUTION:A surface-oxidized carbon fiber for reinforcing a composite material is immersed in an aqueous solution of an electrolyte such as NaOH, sulfuric acid, an oxalate or a carbonate, and the differential capacity of an electrical double layer of a thickness of about 10Angstrom present between the immersed carbon and the solution is promptly measured by an impedance bridge method, DC polarography, coulostatic analysis or the like. After the degree of oxidation of the surface oxidized carbon fiber, namely, the bonding strength to a matrix resin is evaluated from the obtained value and the optimal point of the degree of oxidation is determined, this carbon fiber is kneaded with a matrix resin such as an epoxy resin, nylon or PP to obtain a composite material in which the carbon fiber and the matrix resin can be bonded together with an excellent bonding strength.