RESUMEN
Polymeric materials are used in various environments in which they are subjected to different stresses. In this setting, samples of poly[methyl methacrylate] were treated in aqueous salt solutions at 100 degree C for 20 min. The Thermal Step Method [T S M] and the Thermally Stimulated Discharge Current method [T S D C] were used to characterize the electrical state of these samples. In order to study the influence of ageing process on polarization and space charge distribution, air-aged samples were left for one year on aluminium paper at room temperature. The TSM and the TSDC measurements were then applied on aged samples. The comparison between space charge distributions and TSDC currents measured before and after ageing, shows that the ageing process affects the space charge distribution. PACS numbers: 81.90.+c, 81.40.Tv, 77.22.Ej