Theoretical estimation on electrical conductivity, synergy effect and piezoresistive behavior for nanocomposites with hybrid carbon nanotube/graphene based on modified Bethe lattice method

Abstract In this work, based on the modified Bethe lattice method and excluded volume theory, a conductivity prediction model was proposed for ternary nanocomposites such as carbon nanotubes, graphene nanoplatelet and epoxy, and the influence trend of filler size change on the overall conductivity was also analyzed. The synergy effect was then analyzed based on the above model, and it can be concluded that the enhanced synergy effect between carbon nanotubes and graphene nanosheets is the result of the competition between the geometric synergy effect (whether enhanced or not) and the electrical conductivity of the filler. Moreover, based on this prediction model, we extended a piezoresistive model under tensile strain and explored the effects of filler dosage, size and work function of polymer matrix on piezoresistive effect. It is found that the ternary conductive polymer with enhanced synergy in conductivity also has the chance to have a higher gauge factor, which is valuable for the application of flexible pressure sensors. Although our discussion focuses on the two fillers of carbon nanotubes and graphene, this heuristic prediction model can also be applied to other ternary nanocomposites.