Nanocomposites and nanomaterials
Conductivity of polymer composites with nanocarbon filler
Ovsiienko I.V., Tsaregradskaya T.L., Vovchenko L.L., Matzui L.Yu., 
 Len T.A., Saenko G.V., Heraskevych V. M.

Taras Shevchenko National University of Kyiv, Department of Physics
01601, Volodymyrska st. 64/13, Kyiv, Ukraine
E-mail: okalenyk@ukr.net

In the work the results of complex investigations of electrical conductivity of composites based on nanocarbon fillers with different types of polymer matrix are presented. As nanocarbon fillers the carbon structures of different size, phase composition and dimensionality, in particular, termoexfoliated (TEG) and twice expanded graphite (TEG2), graphite nanoplatelets (GNPs), carbon nanotubes (CNTs) have been used. For preparation of composites three polymers (polyvinyl acetate (PVA), phenol-formaldehyde resin (PFR) and silicon -organic binder (SO)) have been chosen. The concentration of nanocarbon filler ranged from 0.02 to 0.96 mass parts. The electrical resistance of obtained polymer-nanocarbon specimens perpendicular and parallel to the compression axis at room temperature and perpendicular to the compression axis in the temperature interval from 77 K to 293 K has been measured by a four-probe compensation method.
Figure presents the temperature dependences of relative conductivity σ/σ77(T) for polymer composites with different nanocarbon fillers.
	As can be seen from the Figure, for polymer composites with the same concentration of nanocarbon fillers of different structure and dimension, the character of the conductivity temperature dependence is significantly different.
In the work the factors causing the temperature dependence of conductivity σ(T) for composites with different types of nanocarbon filler and polymer matrix are analyzed in detail.
	
Figure. Dependences σ/σ77(T) for polymer composites based on PFR with different nanocarbon fillers (mass percent): 
1 TEG (7.8%); 2 TEG (10%); 3 GNPs (8.5%); 4 TEG(2) ( 10%); 5 GNPs (10%).