Theory of electrical conductivity and dielectric permittivity of highly aligned graphene-based nanocomposites

Xiaodong Xia, Jia Hao, Yang Wang, Zheng Zhong, George J. Weng

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15 Scopus citations

Abstract

Highly aligned grapheme-based nanocomposites are of great interest due to their excellent electrical properties along the aligned direction. Graphene fillers in these composites are not necessarily perfectly aligned, but their orientations are highly confined to a certain angle, θ, with 90° giving rise to the randomly oriented state and 0° to the perfectly aligned one. Recent experiments have shown that electrical conductivity and dielectric permittivity of highly aligned graphene-polymer nanocomposites are strongly dependent on this distribution angle, but at present no theory seems to exist to address this issue. In this work we present a new effectivemedium theory that is derived from the underlying physical process including the effects of graphene orientation, filler loading, aspect ratio, percolation threshold, interfacial tunneling, and Maxwell-Wagner-Sillars polarization, to determine these two properties. The theory is formulated in the context of preferred orientational average. We highlight this new theory with an application to rGO/epoxy nanocomposites, and demonstrate that the calculated in-plane and out-of-plane conductivity and permittivity are in agreement with the experimental data as the range of graphene orientations changes from the randomly oriented to the highly aligned state. We also show that the percolation thresholds of highly aligned graphene nanocomposites are in general different along the planar and the normal directions, but they converge into a single one when the statistical distribution of graphene fillers is spherically symmetric.

Original languageEnglish (US)
Article number205702
JournalJournal of Physics Condensed Matter
Volume29
Issue number20
DOIs
StatePublished - Apr 13 2017

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All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics

Keywords

  • dielectric constant
  • electrical conductivity
  • graphene nanocomposites
  • highly-aligned
  • interface effects

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