Electronic transport properties of highly conducting vapor-grown carbon fiber composites

We have measured the electrical resistivity and thermoelectric power of commercial vapor-grown carbon fibers and fiber composites from 4 K to 300 K. Post-growth heat treatment decreased the resistivity and moderately increased the magnitude of the thermopower. Thermoelectric measurements on fiber composites showed that the host material altered the resistivity but had little effect on the thermopower. Thermopower data suggest that the fibers in the composite material have a smaller degree of graphitization than isolated fibers.