[SY-H11] Symposium H-11

[SY-H11] Relation between deformation and electrical conductivity for electroconductive polymer nanocomposites with highly segregated structure

^○Oleg V. Lebedev¹, Sergey Abaimov¹, Alexander Ozerin², Anton Trofimov¹, Iskander Akhatov¹ (1.Center for Design, Manufacturing and Materials, Skolkovo Institute of Science and Technology, Russia, 2.Laboratory of the Structure of Polymer Materials, N.S. Enikolopov Institute of Synthetic Polymer Materials of RAS, Russia)

Polymer composites with highly non-uniform distribution of nanoscale filler in a matrix (filler forming a so-called segregated structure) possess many interesting properties, such as very low percolation threshold and distinct non-linear piezoresistance effect. To study the dependence of the loss in electrical conductivity on the uniaxial deformation and 3D expansion degree, multiscale finite-element analysis was conducted for polymer matrix containing carbon nanotubes. At the first stage of this work, a uniform distribution of dense-packed and entangled nanotubes was created within a thin planar RVE with polyethylene properties. The response of RVE’s electrical conductivity to a variety of loading conditions was studied to simulate the response of different parts of a segregated structure on the nano-level to the external loading applied at macro-level. In particular, the planar RVE was oriented at different angles relatively to the axis of macroscopic uniaxial loading and progressively deformed to observe non-linear effects. For each pair angle/deformation, a value of effective electrical conductivity was calculated by an external procedure (Python script), accounting for the Kirchhoff's circuit laws. In the result, an analytical functional dependence of the electrical conductivity on RVE’s angle and degree of deformation was developed and compared with the experimental results obtained for uniaxially-deformed electroconductive nanocomposite. At the second stage, a finite-element micro-level model of the segregated structure, recreated from the experimentally observed filler distribution in a composite, was created. The elements of the volume corresponding to the segregated highly filled areas were modeled as having effective electroconductive properties that obey the previously developed conductivity and angle/deformation analytic relation. The micro-level model was uniaxially deformed and thermally treated to introduce expansion of the matrix, and for each degree of deformation or expansion the effective electrical conductivity of the material was calculated. For the obtained dependencies, an analytical expression was developed and was compared with the experimental results for a composite with highly segregated structure.