Résumé
One of the main targets of the research in the field of polymer nanocomposite dielectrics is to obtain new materials with improved dielectric properties (resistivity, dielectric strength, permittivity and dielectric losses). In this paper the variation of the real part of the permittivity and of the loss tangent with the frequency are investigated for three formulations of nanocomposites obtained from polyethylene filled with nanoparticles Of SiO2, TiO2 and Al2O3, respectively. The influence of the filler concentration (between 2 and 10 wt%) on the dielectric behavior of the nanocomposite is analyzed as well.
To simulate the electrical behavior of the polymer-filler interface which might explain the experimental results a 3D electrostatic model proposed on the basis of Tanaka's multi-core model is discussed. This model allows one to study the influence of several parameters such as the nanoparticle diameter, thickness of the interface layers, concentration and permittivity of the nanoparticles or the permittivities of the interface layers, on the effective permittivity of a plane nanodielectric sample.