ELECTRICAL-PROPERTIES OF LAMINATED EPOXY CARBON-FIBER COMPOSITE

This work deals with the effect of temperature on the electrical properties of laminated epoxy composites containing 60% by volume of commercial unidirectional carbon fibers. The temperature was varied from 30-degrees-C to 120-degrees-C and the frequency range was from 10 Hz to 10 kHz. It is found that the impedance decreases with increasing temperature and is inversely proportional to the number of layers in the specimen. 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 increasing number of layers was explained in terms of the existence of electrical contacts and bridges both between and within the fibers, in the carbon fiber layers. The activation energy results indicate that there are two conduction mechanisms in this laminated composite.