Dielectric properties of conducting polymer composites at microwave frequencies
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The dielectric properties of conducting polymer composites containing polypyrrole (PPy) crushed films, PPy powder, polyaniline (PAn) base and acid powders as the dispersants and silicone rubber and vinyl ester as matrix materials have been investigated in the frequency range 2-18 GHz. The dielectric parameters such as the real part, ε′, and imaginary part, ε″, of the permittivity and loss tangent, tanδ, increase with increasing conductivity and concentration of the dispersant. The geometrical shape of the dispersant governs the ability of conductive network formation which is indicated by a large drop in the resistivity of the composite. Also, dispersant/matrix interactions and physical properties of the matrix influence the agglomeration of the dispersant phase which, in turn, affects the dielectric properties of the composites. Flakes of PPy obtained by crushing highly conductive films and large PAn powder aggregates were unable to form a conducting network. The composites without a network of dispersant exhibit low dielectric parameters. On the other hand, high values of tan δ ranging from 0.7–1.1 were achieved for the PPy powder (15 parts)/silicone rubber composites where a conducting network was observed.
KeywordsPolyaniline Dielectric Property Loss Tangent Polypyrrole Silicone Rubber
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- 15.A. G. MacDiarmid, J. C. Chiang, A. F. Richter, N. L. D. Somasiri and A. J. Epstein, in “Conducting Polymers Special Applications”, edited by Luis Alcácer (Reidel Dordrecht, 1987).Google Scholar
- 16.Hewlett-Packard Product Note no. 8510-3.Google Scholar
- 19.S. K. Bhattacharya (ed.), “Metal-Filled Polymers: Properties and Applications” (Marcel Dekker, New York, 1986).Google Scholar
- 22.J. Gurland, Trans. Metall. Soc. AIME 236 (1966) 642.Google Scholar
- 26.K. Lichtennecker, Phys. Z. 19 (1918) 374.Google Scholar
- 27.For example, P. Hedvig, “Dielectric Spectroscopy of Polymers” (Hilger, Bristol, 1977) p. 282.Google Scholar
- 28.T. A. Ezquerra, F. Kremer and G. Wegner, in “Dielectric Properties of Heterogeneous Materials”, edited by A. Priou, “Progress in Electromagnetics Research 6” (Elsevier, New York, 1992).Google Scholar
- 30.S. Wu, “Polymer Interface and Adhesion” (Marcel Dekker, New York, 1982).Google Scholar