Polymer dielectrics are widely used in electrical and electronic apparatus and devices because of their capability to insulate conductors, withstand high fields and suffer negligible conductive losses. Their near-to-zero conductivity has been explained in terms of long-accepted theories of electronic and ionic transport that lead to the accumulation of local net charge regions at high electric fields. Here the authors describe a previously unknown conduction mechanism consisting of small bipolar ultra-fast charge pulses crossing the polymer with the mobility, as large as, 4 to 5 orders of magnitude greater than that of the previously known. The authors show that this motion is a consequence of molecular relaxation processes triggered by the electric field locally enhanced by the pulses themselves. Pulse accumulation at the electrodes increases interface field and thus contributes substantially towards premature failure in insulating dielectrics in DC fields.

高分子电介质具有绝缘导体，承受高电场且可忽略不计的导电损耗的能力，因此广泛用于电气和电子设备。它们的接近于零的电导率已根据长期接受的电子和离子迁移理论进行了解释，这些理论导致了高电场下局部净电荷区域的积累。在这里，作者描述了一个未知的传导机制，该机制由小的双极超快电荷脉冲与具有迁移率的聚合物交叉构成，其迁移率比先前已知的大4至5个数量级。作者表明，这种运动是由脉冲本身局部增强的电场触发的分子弛豫过程的结果。