Contribution à l’étude de l’influence d’une décharge couronne sur les propriétés de films minces de polyimide en vue de leur utilisation dans le biomédical.

Abstract

In this work, an experimental study and analysis of the effects of environmental relative humidity (RH %) on the transport mechanisms of electrical charges in PI films have been presented. The evolution of the surface potential decay after negative corona charge deposition have been investigated and analyzed by examining the characteristics to straightly obtain information about trap energy distribution in PI films for different relative humidity levels. The calculating method of trap energy distribution is based on the double exponential fitting analysis of surface potential decay measurements. The results indicate that for different charging voltage levels, the surface potential decays faster in humid air than in relatively dry ones. The recorded corona charging current confirms the interpretation of surface potential decay measurements. Both shallow and deep trap distribution moves towards lower energy levels, indicating an increase in the film’s electrical conductivity. A model has been developed for the simulation of a positive corona discharge in a needle-plane configuration at atmospheric pressure. The spatial-temporal variations of the electric field, the electrons, positive and negative ions have been investigated.