Hopping current and charge storage in polymer electret

In this paper, the formulas of hopping current in polymer and polymer electret are derived. By these formulas, a theoretical discharge equation of polymer electret can be derived. The step-size of hopping electrons, calculated from the isothermal decay data of electrets, are about 10^-8 m. The average size of crystalline regions in polymers are also 10^-8 m in order. This supports the above equations experimentally. All the facts and points in this paper support the suggestion that firmly stored charges are almost trapped in the bands of crystalline regions of electret