Thermally Stimulated Depolarization Current analysis to the determination of polarization and relaxation parameters in aged PMMA

Thermally Stimulated Depolarization Current (TSDC) technique has been extensively used to study the main and secondary relaxations process in various materials, such as polymers. In this work, samples of amorphous polar poly(methyl methacrylate) (PMMA) are submitted to a particular thermal aging with different durations, and then TSDC measurements are made. Theoretical model is applied for the analysis of complex TSDC spectra for aged PMMA samples. The polarization was determined for each aged PMMA sample, as a sum of single depolarization process contribution. The different relaxation mechanisms are recognized and their relative contributions to the polarization of polymer are evaluated. The obtained results show that the thermal aging affects slightly the primary and the secondary, dipolar relaxations and more strongly the space charges relaxation.