Electrical, mechanical, and thermal characteristics of nonwoven fabric heating sheets containing chopped carbon fibers

Discontinuous carbon fiber (CF) composite materials have potential as heating elements, but the practical realization of heat-generating characteristics has been restricted by the high resistance of conventional CF composites. In this study, the electrical, mechanical, and thermal properties of heating sheets with discontinuous CFs were investigated. The properties were found to vary depending on CF length and the dispersant content. Sheets containing CFs 6 mm in length and 16.9–45.8 wt% dispersant showed optimum electrical and mechanical properties for heating elements. The CF heating sheets showed a low volume resistivity and a high glass transition temperature. The far-infrared emissivity of the CF heating sheets corresponded to 90% of that of a black body and was higher than that of a nichrome wire. Internal energy saturation of the CF heating sheets occurred within 5 s owing to low heat capacity. These features indicate that the CF heating sheets are suitable for application as a portable heating element.