Preparation Of Graphene-based Film And The Research On Its Thermal Conductivity

Graphene, a single layer of a two-dimensional carbon lattice, exhibits remarkable thermal conductivity as well as excellent mechanical flexibility and low density and is considered to be an ideal heat dissipation material. A particularly attractive option is to design and develop highly flexible free-standing films consisting of graphene sheets which are useful in many applications. However, there are very few reports on thermal transport properties of these films. It remains elusive how well a film composed of graphene sheets conducts heat and how tailor the thermal conductivity of these films for various purposes.The graphite oxide sheets were reduced using anhydrous ethanol, ethylene glycol and hydrazine hydrate as reducing agents, respectively, and the corresponding product was designated as GC-AHy, GC-EHy and GC-Hy respectively. The results showed that oxygen contents of GC-AHy, GC-EHy and GC-Hy were25.59%,15.39%and8.72%, respectively, which indicated that the reduction effect of the reductants was in the order of hydrazine hydrate>ethylene glycol>anhydrous ethanol.The effect of treatment temperature on reduction degree of the films composed of graphite oxide sheets during thermal reduction was investigated. The results showed that the oxygen contents of the obtained graphene-based films decreased with the increase of temperature. The destruction of alignment and the creation of macropores between the graphene sheets in the films were observed, which is a result of gas generation and evaporation during thermal reduction of oxygenated functional groups.The thermal conductivity of graphene-based films reduced by anhydrous ethanol was investigated. It is found that the thermal conductivity the film decreased with increasing the film thickness. The thermal conductivity of the film prepared in100℃was better than ones obtained in the other temperature, and with the reduction time extending, the thermal conductivity improved. This result was attributed to the close relationship between the degree of graphitization and the thermal conductivity of the film. In certain range, the graphitization degree of the film improved with the oxygen content reducing, thus the thermal conductivity of the film increased.