Effective DC Conductivity of Polymer Composites Containing Graphene Nanosheets

The effective DC conductivity of polymer-graphene composites is modeled by contact resistance and interphase depth. The resistances of polymer layer and graphene nanosheets in the contact spaces define the contact resistance. Also, the effective filler concentration reveals the interphase role in the conductivity. So, the effective conductivity is correlated to the concentration, thickness and conduction of graphene in addition to interphase depth, tunnel resistivity, contact diameter, contact distance and percolation onset. Experimental data of some samples are fitted to the predictions of developed model. The impressions of factors on the effective conductivity are justified supposing the contact resistance and network performance. Thin graphene nanosheets and wide contacts suggest a high effective conductivity. In addition, the effective conductivity directly links to the graphene loading, while the significant graphene conduction cannot affect it. The small contact area between nanosheets weakens the conductivity, but a high effective conductivity is achieved by big contact area and poor percolation onset.