Determination of threshold electric field for charge injection in polymeric materials

Accurately determining the threshold electric field at which charge injection from the electrodes starts is important for reliable operation of dielectric materials as the presence of charge in the material can lead to electric field enhancement, resulting in degradation and early failures of the material. The two methods in charge measurements that have been commonly used to find out the threshold field have been compared to the proposed method, which overcomes the drawbacks of the two methods. Such method offers (i) high sensitivity as the effect of capacitive charge has been eliminated and (ii) contributions from both mobile and slow charges; hence, providing a more accurate value for the threshold electric field. Based on the proposed method, it has been found that the threshold field for low density polyethylene is around 8 kV/mm, which is lower than the reported value obtained from the other methods.