On polyethylene-polyaniline composites

Mechanical tests (elongation at break and tensile strength), DC electrical conductivity, and electron spin resonance (ESR) investigations on polyethylene-polyaniline blends are reported. While the concentration of the conducting polymer in the blend is raised, the DC electrical conductivity is increased, and the mechanical properties (tensile strength and elongation at break) are depressed. An universal expression for the dependence of mechanical and electrical properties on the concentration of conducting particles is empirically suggested and supported by experimental data. The ESR spectra are single lines, located close to the g = 2.0 value and assigned to the conduction electrons (with uncoupled electronic spins). The reduced asymmetry of the resonance supports the presence of mesoscopic conducting domains. The features of ESR spectra and the connection between ESR parameters and DC conductivity reflects the major role of polarons hopping in the electron transport and rules out the presence of both low and high spin bipolarons. (C) 2003 Elsevier Ltd. All rights reserved.