Nanocomposites and nanomaterials

Influence of filler morphology on electrical and thermal properties of the composites based on the polyethylene filled with thermally expanded graphite
O.V. Maruzhenko1,2, Ye.P. Mamunya1, S. Pruvost2, G. Boiteux3, L.Yu. Matzui4, L.L. Vovchenko4
1 Institute of Macromolecular Chemistry of NAS of Ukraine
48, Kharkivske shose, Kyiv, 02160, Ukraine
E-mail: a.v.maruzhenko@gmail.com
2 Université de Lyon, INSA Lyon, Ingénierie des Matériaux Polymères;
UMR CNRS 5223, 69 621 Villeurbanne Cedex, France
3 Université de Lyon, Université Lyon 1, Ingénierie des Matériaux Polymères;
UMR CNRS 5223, 69 622 Villeurbanne Cedex, France
4 Department of Physics, Taras Shevchenko National University of Kyiv;
Volodymyrska Str., 64/13, Kyiv 01601, Ukraine.

The electrical and thermal conductivities of polymer nanocomposites based on ultrahigh molecular weight polyethylene (UHMWPE) and high-density polyethylene (HDPE) were studied with a segregated and random distribution of the nanofiller, which was thermally expanded graphite (TEG). The segregated structure has an ordered 3D distribution of filler particles in a form of framework in a polymer matrix with high local concentration φloc, which is significantly higher than the average φ for the entire volume of the composite, φloc >> φ. Concentration dependence of electrical conductivity is described by the percolation equation =0(-c)t with percolation threshold – 0.5 and 6.9 vol.%, critical exponent t – 4.0 and 2.6, parameter σ0 – 530 and 0.43 S/cm for the segregated and statistical systems, respectively. Thermal conductivity for both systems is described by a parallel model, which can be explained by the lengthy structure of the filler in the volume of the polymer. The segregated structure has a higher thermal conductivity of the filler λf = 33 W/m·K versus λf = 15 W/m·K for the random distribution of the filler. The higher values of conductivity parameters λf, σ0, and lower percolation threshold φc for the segregated structure are explained by the high local concentration of filler particles in the framework, which ensures better transfer of electrical and heat flow through the presence of direct contacts of particles in the framework compared to its random distribution.