Corona poling of polyvinylidenefluoride

A variety of charging techniques may be used for poling polyvinylidene-fluoride (PVDF) in order to obtain the desired piezoelectric [1] or pyroelectric [2] properties. The classical thermoelectret-forming method [3] requires heating of the sample. With this technique, local breakdown at a weak sample spot or at the electrode edges short-circuits the poling electrodes and thus prevents further poling. This effect is avoided by employing electrodes with a relatively high resistance distributed over the whole sample area: local breakdown then draws its current only from a small portion of the electrode area and therefore cannot short-circuit the whole electrode.