Enhanced Conductivity of Reinforced Carbon Fibers Induced by Air Plasma Etching of Composites

In this study we investigate whether carbon fibers reinforcing a polymer matrix could be utilized as starting material to produce embedded but highly conductive carbon-based structures. Our considerations are based on finding showing that solution based oxidative or plasma etching treatment of carbon nanotubes results in graphene formation. Hence, graphene structures are achieved by rolling-up of the carbon nanotubes by application of Ar plasma etching of poly (methyl methacrylate). The disadvantage of this method is that it is a complex and time-consuming process. In contrast, we show that low cost, large patterned conductive carbon structures can be achieved directly with carbon fibers reinforced in epoxy-based composite. Raman and in-situ SEM impedance studies reveal a significant dependence of the composite conductivity specific position in respect to the fiber/matrix composite. Remarkable plasma etching effect is reflected in retained surface activity of reinforced carbon fibers even after a period of one year. Preserved structural integrity of embedded fibers coupled with their significantly enhanced conductivity in the matrix composite broaden up range of possible composite applications. Using defined thickness of matrix composite, enhanced conductivity of embedded fibers is envisioned as a second function of reinforced carbon fibers in multifunctional CFRP composite applications such as sensing and resistive heating.