The role of the interfacial layer in time -temperat ure dependence of the electrical resistance of hi gh-density polyethylene /carbon black composites
In order to explain the time-temperature dependence of the electrical resistance of HDPE filled with carbon black, a model is proposed, in which an important role is played by the interfacial layer between the solid-phase filler and the polymer matrix. It is shown that the change in the structure of the macromolecules in the interfacial layer can be characterized using fractal concepts. The fractal dimension increases as the size of the filler particles decreases, and this is accompanied by a decrease in electrical resistance. During isothermal annealing treatment of the samples the fractal dimension of the interfacial layer is changed from 2.3 to 3. Correlations of the observed parameters are presented. The activation energy of increasing resistance in the initial period of the sample treatments is calculated. It is shown that the electrostatic field restrains the increase of the fractal dimension of the interfacial layer and the change in the resistance of the filled systems.