ELECTRICAL-PROPERTIES OF LAMINATED EPOXY CARBON-FIBER COMPOSITE

This work deals with the effect of temperature on the electrical prope rties of laminated epoxy composites containing 60% by volume of commer cial unidirectional carbon fibers. The temperature was varied from 30- degrees-C to 120-degrees-C and the frequency range was from 10 Hz to 1 0 kHz. It is found that the impedance decreases with increasing temper ature and is inversely proportional to the number of layers in the spe cimen. The calculated dielectric constants show a strong dependence on the frequency below 100 Hz, and attain relatively constant values for frequencies greater than 100 Hz. The decrease in impedance with incre asing number of layers was explained in terms of the existence of elec trical contacts and bridges both between and within the fibers, in the carbon fiber layers. The activation energy results indicate that ther e are two conduction mechanisms in this laminated composite.