Siberian Federal University

In this paper we consider the effect of oxidative treatments on the properties of multiwalled carbon nan- otubes (MWNT). The experimental temperature dependence of electrical conductivity (in the temperature range 4,2-293 K) and field dependence of magnetoresistance (in fields up to 9 Tl at 10 K) of the samples with MWCNT modified by oxidation of the surface layers, as well as the composites based on them. It was established that the oxidation of the surface layers of MWCNTs in acid solutions leads to a change in the temperature dependence of electrical conductivity. Introduction of MWCNTs in a dielectric matrix of polymethylmethacrylate (PMMA) leads to the dependence of the conductivity close to that typical for hopping conductivity with variable hopping length, three-dimensional case.