Colossal permittivity of carbon nanotubes grafted carbon fiber-reinforced epoxy composites

Giant dielectric-constant-ceramic materials have been paid much attention for their potential applications in high-capacity capacitors due to their high energy storage density. Dielectric constants of composite materials are generally low compared with ceramic materials. In this paper, carbon nanotubes (CNTs) were successfully prepared on carbon fibers (CFs) surface by chemical vapor deposition (CVD) and CNTs-CFs/epoxy composites were obtained by hot-pressure molding. Effects of CVD atmosphere on composites dielectric performance were investigated. The composites exhibited a surprisingly high dielectric constant about 200,000 (60 kHz) when the ratio of C2H2, H2 and N2 was 6:6:12 in the CVD process.