The effect of coupling agent on electrical and mechanical properties of carbon fiber/phenolic resin composites

Carbon fiber/phenolic resin composites were prepared by changing the content (5-10 wt%) of short carbon fibers. To investigate the effect of carbon fiber treatment on the electrical and mechanical properties of the composites, three specimens were prepared: the short carbon fiber treated to remove size (called USCF); the carbon fiber oxidized with nitric acid (called NAOCF); and the fiber oxidized with nitric acid and treated with coupling agent glutaric dialdehyde (called GTDACF). The GTDACF composite had higher electrical conductivity and better mechanical property than the other composites with the same content of carbon fibers. The surface treatment methods affected the dielectric behaviors of the composites with short carbon fibers while they did not affect those of the composites with fabric type carbon fibers. From these observations, the coupling agent improved adhesion between the carbon fiber and the phenolic resin by forming a chemical bond between fiber and resin. The coupling agent also affected the flow and dispersion of the short carbon fiber in the phenolic resin during compression molding, resulting in the higher electrical conductivity and better mechanical property of GTDACF composite. (C) 2000 Elsevier Science Ltd. All rights reserved.