Electrical and thermal conductivities of reduced graphene   oxide/polystyrene composites
  The author reports an experimental study of electrical and thermal transport in reduced graphene oxide (RGO)/polystyrene (PS) composites. The electrical conductivity ($\sigma$) of RGO/PS composites with different RGO concentrations at room temperature shows a percolation behavior with the percolation threshold of ~ 0.25 vol.%. Their temperature-dependent electrical conductivity follows Efros-Shklovskii (ES) variable range hopping (VRH) conduction in the temperature range of 30 to 300 K. The thermal conductivity ($\kappa$) of composites is enhanced by ~ 90 % as the concentration is increased from 0 to 10 vol.%. The thermal conductivity of composites approximately linearly increases with increasing temperature from 150 to 300 K. Composites with a higher concentration show a stronger temperature dependence in the thermal conductivity. 
Wonjun Park, Jiuning Hu, Luis A. Jauregui, Xiulin Ruan, and Yong P.   Chen
cond-mat.mtrl-sci