Thermal conductivity of epoxy composites filled by thermally reduced graphite oxide with different reduction degree

A series of selectively reduced graphite oxide was prepared by thermal reduction of graphite oxide at different annealing temperatures and used as fillers to enhance thermal conductivity of epoxy composites. The reduction degree of selectively reduced graphite oxide increases with annealing temperature changing from 600 degrees C to 1000 degrees C The out-of-plane thermal conductivity (K-o) of selectively reduced graphite oxide/epoxy composites is remarkably higher than that of graphite oxide/epoxy. For the selectively reduced graphite oxide obtained at 1000 degrees C, K-o reaches 0.674W/mK when filler content is 5.4wt%, which is 450% of pure epoxy. The enhanced K-o can be attributed to the better dispersion of selectively reduced graphite oxide in epoxy and their edges overlap to form effective thermal conductive paths in epoxy matrix. However, the achieved thermal conductivity enhancement is still comparatively lower than that of selectively reduced graphite oxide with higher reduction degree, since the interfacial bonding strength between selectively reduced graphite oxide and epoxy decreases when reduction degree of selectively reduced graphite oxide flakes becomes higher.