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Dielectric properties of multiwall carbon nanotube-epoxy composites

S. PALADE1, A. PANTAZI1, C. BERBECARU1,2,* , E. VAJAIAC1,3, A. STEFAN3, A. MATEI4, V. MELTZER5, E. PINCU5, D. DRAGOMAN1,6

Affiliation

  1. Faculty of Physics, University of Bucharest, P.O. Box MG-11, 077125 Bucharest, Romania
  2. Romanian Materials Science - Crystal Growth Society, Bucharest-Magurele, 077125, Romania
  3. National Institute for Aerospace Research and Development „Elie Carafoli”, 061126 Bucharest, Romania
  4. National Research and Development Institute in Microtechnologies, Str. Erou Iancu Nicolae 126 A, 077190 Bucharest, Romania
  5. Faculty of Chemistry, University of Bucharest, Bd. Regina Elisabeta 4-12, 030018 Bucharest, Romania
  6. Academy of Romanian Scientists, Splaiul Independentei 54, 050094 Bucharest, Romania

Abstract

Resin and functionalized multiwall carbon nanotubes (fMWCNT) were used to obtain composites, cured at room temperature (RT). Dielectric measurements show changes of permittivity and losses in cooling-heating cycle with nonreproducible values above 50 oC. Interplay of segments with increased mobility due to increasing resin temperature, the differences between thermal expansion coefficients between resin and fMWCNT, spatial rearrangements in samples and post curing effects could explain the evolution of dielectric parameters versus temperature. Permittivity and losses show strong frequency dependence associated with reducing contributions of different polarization mechanisms at increasing frequencies. Permittivity, losses and electrical conductivity of the samples reveal a tremendous increase with nanotubes concentration at the percolation threshold. Percolation and tunneling mechanisms at RT and thermally activated mechanisms, which dominates the electrical conduction at high temperatures, can explain the temperature dependence of samples’ conductivity. Electrical measurements also showed non-reproducible values at heating and cooling beyond 55 oC..

Keywords

Carbon nanotubes, Polymer-matrix composites, Electrical properties, Infrared (IR) spectroscopy, Differential scanning calorimetry (DSC).

Submitted at: Sept. 22, 2014
Accepted at: Sept. 9, 2015

Citation

S. PALADE, A. PANTAZI, C. BERBECARU, E. VAJAIAC, A. STEFAN, A. MATEI, V. MELTZER, E. PINCU, D. DRAGOMAN, Dielectric properties of multiwall carbon nanotube-epoxy composites, Journal of Optoelectronics and Advanced Materials Vol. 17, Iss. 9-10, pp. 1325-1332 (2015)