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 conten t (5-10 wt%) of short carbon fibers. To investigate the effect of carbon fi ber treatment on the electrical and mechanical properties of the composites , three specimens were prepared: the short carbon fiber treated to remove s ize (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 electr ical conductivity and better mechanical property than the other composites with the same content of carbon fibers. The surface treatment methods affec ted the dielectric behaviors of the composites with short carbon fibers whi le they did not affect those of the composites with fabric type carbon fibe rs. From these observations, the coupling agent improved adhesion between t he carbon fiber and the phenolic resin by forming a chemical bond between f iber and resin. The coupling agent also affected the flow and dispersion of the short carbon fiber in the phenolic resin during compression molding, r esulting in the higher electrical conductivity and better mechanical proper ty of GTDACF composite. (C) 2000 Elsevier Science Ltd. All rights reserved.