Carbon nanotube agglomeration effect on piezoresistivity of polymer nanocomposites

•Modeled piezoresistivity of agglomerated nanocomposites by multiscale CNT networks.•Quantified reduced electrical conductivity & piezoresistivity due to agglomeration.•Studied effects of CNT properties and agglomeration size on piezoresistivity.

Carbon nanotube (CNT) agglomeration exists inevitably in all CNT-polymer composites. This paper quantified the effect of CNT agglomeration on the piezoresistivity of CNT-polymer composites. A new multiscale model of 3-dimensional deformable CNT percolating networks has been developed, where the CNT agglomerates were modeled as second phases embedded randomly in the polymer matrix. The newly developed model agrees quantitatively with experimental data. The study found that the CNT agglomeration is responsible for the reduced electrical conductivity and nonlinearity of piezoresistivity with respect to the zero strain. Its effect can be quantified by the newly developed model. Parametric analyses were conducted to show the effects of morphology and electrical properties of CNTs, the Poisson's ratio of CNT-polymer composites and the extent, internal density and size of CNT agglomeration on the electrical conductivity and piezoresistivity. The current work provides a useful analysis tool for designing smart sensing and multifunctional polymer composites.

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