Characterization of the dipole processes of insulating materials used in aeronautical cables.

The studies of this thesis are focused on aeronautic Polymers materials and their dielectric properties, in order to analyze the relaxation times for the materials of interest under an applied electric field, and in order to increase the work operations of the Novocontrol dielectric spectroscopy measurement machine available in the LAPLACE laboratory. In this context, the research team DSF in collaboration with MDCE, from LAPLACE laboratory, has developed in 2019 a numerical model taking into account the polar mechanisms of the polymer insulators used in the aeronautic industry. However, this theoretical model, is not yet validated. Therefore the aim of this thesis, is to make it possible to validate this theoretical model, then by a series of measurements with dielectric spectroscopy(D.S.) for different materials of interest, different frequencies and temperatures; the measurements consist on the measuration of the phase difference between current and voltage applied to the samples, in order to calculate the permittivity values under different working conditions. The permittivity trend is therefore analyzed to find the polar relaxation under thermoelectrical stresses, and the model will then have to calculate the current density (and from the current density is directly calculated the dissipated energy) of the measured data with dielectry spectroscopy, and the validation will be done if the future measurement values of the current density correspond to the calculated one by the model. For this reasons, the main part of the work for this thesis consist in measurements trought the dielectric spectroscopy (using the following polar materials: Polyimide(PI) and PTFE ) under different working conditions and analyze the results in order to evidence polarization phenomena, because the purpose of this part of the validation process is to have the better polar relaxation data for the future work.