Evaluation of dielectric relaxation parameters from TSDC analysis of pristine and ion irradiated kapton-H polyimide

The TSD currents of pristine and 75 MeV oxygen ion irradiated kapton-H polyimide were obtained in the temperature region 20-250 degrees C. The samples were polarized under different temperature windows (temperature regions in the absence of electric field) termed as window-I (75-55 degrees C) and window-II (90-75 and 55-20 degrees C). The TSDC characteristics consist of two current maxima termed as beta'-peak and beta-peak around 30 and 120 degrees C, respectively. The peak magnitude significantly depends on temperature windows. The strength of the beta'-peak and beta-peak is being affected in opposite modes in the pristine and ion irradiated samples, as pristine samples show an enhancement in the beta'-peak while there appears a suppression in the beta'-peak in case of ion irradiated samples. The precise determination of the dielectric relaxation parameters has been made by elementary Debye processes. (C) 2011 Elsevier B.V. All rights reserved.