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The great influence of O 2 on the electrical aging of polypropylene films. The lifetime of the capacitor model with 2x13.6 μm-thick PP films is about 25 h with O 2 saturated liquid and more than 1500 h without O 2 . Two different degradation are obtained on a given film and good agreement is shown between electrical (breakdown voltage) and physicochemical measurements (FTIR spectroscopy)

The transient space‐charge‐limited current technique developed in crystals is made to fit polar liquids: First, from a theoretical point of view the injection is no longer only limited by space charge, the electrode–liquid contact being non‐Ohmic; second, from an experimental point of view, the electric field distribution is at every moment determined by means of the electro‐optic Kerr effect, and known ions are injected by permselective membranes. Applying this technique makes it possible to estimate the mobility of different carriers injected into different polar liquids and brings out high mobility values of about 2 × 10−3 cm2 V−1·sec−1. Account is taken of the influence of bulk liquid motion to explain the high values of ionic velocities obtained.

During unipolar (or ambipolar) injection of charge carriers into an insulating liquid, a liquid motion is generally observed. This motion, generated by the charge carriers, is thought to be responsible for the high carrier mobility which is about 2×10−3 cm3 V−1 sec−1 in nitrobenzene, i.e., an order of magnitude higher than the true mobility value (1.9×10−4 cm2 V−1 sec−1). Recent schlieren photographs strongly support the assumption that when the applied voltage is high enough, for nitrobenzene of the order 103‐104 V, the “self‐generated” motion is turbulent shortly after the voltage is applied. This turbulence invades the undisturbed fluid at practically constant velocity. Neglecting the true carrier mobility and making certain assumptions concerning the turbulent structure, the charge transport and consequently the entrainment can be described to a good approximation by a Lagrangian diffusion process and the charge distribution is governed by a diffusion equation. The latter remains valid during the stea...