Analyzing the frequency and temperature dependences of the ac conductivity and dielectric analysis of reduced graphene oxide/epoxy polymer nanocomposites

• Published in: Journal of materials science Vol. 52; no. 24; pp. 13790 - 13798
• Main Authors: Nioua, Y., El Bouazzaoui, S., Melo, B. M. G., Prezas, P. R. S., Graça, M. P. F., Achour, M. E., Costa, L. C., Brosseau, C.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.12.2017; Springer; Springer Nature B.V
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Collapse; Composite materials; Composites; Crystallography and Scattering Methods; Dependence; Dielectric properties; Electric properties; Electrical conduction; Electrical properties; Electrical resistivity; Electron tunneling; Epoxy resins; Frequency analysis; Graphene; Graphite; Impedance; Laws, regulations and rules; Materials Science; Nanocomposites; Nanoparticles; Percolation; Polymer industry; Polymer matrix composites; Polymer Sciences; Solid Mechanics; Thermal analysis; Graphene Oxide Content; Single Characteristic Frequency; Percolation Threshold; Capacitive Path; Impedance Analysis Measurements
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-017-1462-2

A series of composite materials was fabricated by mixing reduced graphene oxide (rGO) powder particles in an epoxy resin. In this paper, we analyze impedance measurements on these materials over broad frequency and temperature ranges. The real and imaginary parts of the effective complex impedance are well fitted to the Cole–Cole equation. The frequency dependence of the ac conductivity follows Jonscher’s law with relaxation processes characterized by a broad distribution of relaxation times. The imaginary part of the effective electric impedance collapses onto a single master curve using a single characteristic frequency as a scaling parameter. We find that the electrical properties of the samples are strongly influenced by graphene oxide content. Below percolation threshold, the ac transport can be interpreted as due to electron hopping. Further, we find that the frequency-dependent effective impedance measurements overlap on a single master curve in the range of temperatures explored, showing that a single electrical conduction mechanism is operative. Close and above percolation threshold, the ac conduction originates from both electron tunneling and capacitive paths among the rGO nanoparticles in the polymer bulk.