Abstract
The influence of the electrical polarization on the γ-irradiated Fluoroethylene Propylene (FEP) were investigated by Electron Spin Resonance measurements. Initially, after removing the electric field, the ESR spectrum was symmetric but it gradually became asymmetric with the polarization decay in the electret. A weak line, characteristic of volume polarization in the electret, appeared in the asymmetric spectrum. The radiation induced ESR spectra in FEP were attributed to the peroxy radicals, trapped in different matrices. The anomaly in the shape of the spectrum was correlated with the deeper trapping and preferential orientation of the radicals in the polarized crystalline regions.