Renovating nanocomposite design: A novel conductivity model for polymer graphene systems incorporating interphase and tunneling zones

Many papers have studied the electrical conductivity of graphene-filled nanocomposites, but the roles of imperfect interphase in the percolation onset and nanocomposite conductivity were ignored. In this manuscript, two interface parameters including the minimum graphene diameter to transfer its conductivity to the polymer medium (D_c) and interface conduction (ѱ) are defined in polymer composites by graphene size and interphase deepness. Then, the actual converse aspect ratio, real filler portion, and percolation inception are given by graphene size and interphase deepness. Also, a model is developed based on the stated terms for conductivity of graphene-containing composites. The impacts of various parameters on the “D_c,” “ѱ,” actual filler portion, percolation inception, and nanocomposite conductivity are plotted and justified by new equations. Moreover, the forecasts of conductivity and percolation inception are associated to several experimented data. Narrow nanosheets and thick interphase positively govern the “D_c,” interface conduction, actual filler portion, the inception of percolation, and conductivity of system. The maximum interface conduction as 1400 S/m is reached by graphene thickness (t) of 2 nm and interphase depth (t_i) of 6 nm, but the interface conduction largely reduces to 100 S/m at t_i <2.7 nm. These results recommend that reedy nanosheets and bushy interphase cause a high interface conduction in nanocomposites. Furthermore, high nanosheet diameter (D) negatively affects “D_c” and interface conduction, but it produces the low percolation inception and high conductivity. The nanocomposite conductivity reaches 0.9 S/m at D = 5 μm and graphene conductivity of 2 × 10⁵ S/m. Highlights: A conventional model is developed for conductivity of graphene-containing composites. Two interfacial parameters as “D_c” and “ѱ” are considered in the nanocomposites. The forecasts of conductivity are compared to the experimented data of several samples. Narrow nanosheets and thick interphase positively govern the “D_c” and conductivity. Bigger nanosheets negatively affect the “D_c”, but produce a higher composite conductivity.