Charging of polymers by high electric fields

Several polar and non-polar polymers, including polyvinylidene fluoride, polyethylene and polytetra-fluoroethylene were charged by evaporating various metal electrodes onto films of the materials and applying electric fields of the order of 1 MV/cm at various temperatures and times. The charged films were then analyzed by observing the charge transient which results during thermal equilibration following the heating of the electrodes with short (∼1 μsec) pulses of light (thermal pulse measurement of charge distribution due to R. E. Collins). The observed transients are discussed in terms of the charge distributions in the polymers and the relationship between these distributions and the sample history. The usefulness of considering the polymers as having a work function and possible implications of high-field charging on the breakdown strength of solid polymers will be discussed.