Nanocomposites and nanomaterials

Percolation behavior in electrical conductivity in epoxy resin/thermally expanded graphite nanocomposites
Darabut A.M., Lobko Y., Yakovlev Y., Matolínová I., Matolín V.
Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 747/2, 180 00 Prague 8, Prague, Czech Republic 
E-mail: alinadarabut@gmail.com

Nowadays, alternative power energy sources play a crucial role in the energetic technology [1]. The polymer electrolyte membrane fuel cells are one of the key players on this field. For this reason, the creation of the polymer-based electrically conductive composites for fuel cell bipolar plates is important [2]. The balance between the high electrical conductivity, mechanical characteristics, and other properties of bipolar plates is very crucial for effective work of the fuel cells. 
In this work, the polymer composites based on epoxy resin and different thermally expanded graphite (TEG) content were prepared by compression molding. The electrical properties of materials have been carried out by impedance spectroscopy. The results were compared to the electrical properties of polymer composites filled with commercial graphite of different particle size and carbon content.
The percolation behavior of the carbon fillers in the polymer matrix was analyzed. The percolation model used for the fitting of the different series is the statistical percolation model proposed by Kirkpatrick [3] and Zallen [4]. It was obtained that the percolation threshold of the epoxy resin/TEG composites is at 4 vol.%. The critical indexes t is equal 1.6 ± 0.12.

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