Effect of tensile stresses on the breakdown voltage of thin films

We consider the problem of electric breakdown of external varnish-and-paint coatings of aircrafts. It is shown that the formation of the breakdown channel in the dielectric field is associated with rupture of polymer macromolecules in stretched regions. It is revealed in experiments with polyester urethane film that the breakdown voltage (dielectric strength) decreases exponentially with increasing tensile stresses.