COMPENSATION PHENOMENA IN OIL-RESIN MIXTURES - A NEW DIELECTRIC APPROACH TO PERCOLATIVE PROCESSES

The methods of thermally stimulated currents (TSC) together with low f requency dielectric spectroscopy (LFDS) are combined for the first tim e to study percolation phenomena. These take place within oil-resin mi xtures which constitute conductor/insulator-like composite systems. Ea ch of these techniques is shown to describe selectively one of two dif ferent kinds of relaxation processes in the oil component: first, anel astic dipolar movements and second, the circulation of free charges. T he separate qualitative interpretations of the combined TSC/LFDS exper iments lead to convergent estimations of the percolation thresholds of the two basic materials in oil-resin mixtures. The latter appear as c ritical concentrations for which the dielectric relaxation processes e ither comply suddenly with compensation laws or pre-existing compensat ion phenomena change in nature.