A theory of electrical conductivity, dielectric constant, and electromagnetic interference shielding for lightweight graphene composite foams

Journal Article · Sun Aug 28 00:00:00 EDT 2016 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4961401· OSTI ID:22598883

Xia, Xiaodong ^[1]; Wang, Yang; Zhong, Zheng ^[1]

---

1. School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092 (China)

This work was driven by the need to understand the electromagnetic interference (EMI) shielding effectiveness (SE) of light weight, flexible, and high performance graphene composite foams, but as EMI SE of a material depends on its electrical conductivity, dielectric permittivity, and magnetic permeability, the investigation of these three properties also became a priority. In this paper, we first present a continuum theory to determine these three electromagnetic properties, and then use the obtained properties to evaluate the EMI SE of the foam. A two-scale composite model is conceived to evaluate these three properties, with the large one being the skeleton-void composite and the small one being the graphene-polymer composite that serves as the skeleton of the foam. To evaluate the properties of the skeleton, the effective-medium approach is taken as the starting point. Subsequently, the effect of an imperfect interface and the contributions of electron tunneling to the interfacial conductivity and Maxwell-Wagner-Sillars polarization mechanism to the dielectric constant are also implemented. The derived skeleton properties are then utilized on the large scale to determine the three properties of the composite foam at a given porosity. Then a uniform plane electromagnetic wave is considered to evaluate the EMI SE of the foam. It is demonstrated that the electrical conductivity, dielectric constant, and EMI SE of the foam calculated from the developed theory are in general agreement with the reported experimental data of graphene/PDMS composite foams. The theory is further proven to be valid for the EMI SE of solid graphene/epoxy and solid carbon nanotube/epoxy nanocomposites. It is also shown that, among the three electromagnetic properties, electrical conductivity has the strongest influence on the EMI shielding effectiveness.

• OSTI ID: 22598883
• Journal Information: Journal of Applied Physics, Vol. 120, Issue 8; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CARBON NANOTUBES
COMPOSITE MODELS
DIELECTRIC MATERIALS
ELECTRIC CONDUCTIVITY
ELECTRONS
EPOXIDES
FOAMS
GRAPHENE
INTERFERENCE
MAGNETIC SUSCEPTIBILITY
NANOCOMPOSITES
PERMITTIVITY
POLARIZATION
POLYMERS
POROSITY
SHIELDING
SKELETON
SOLIDS
TUNNEL EFFECT