Surface charge decay characteristics for two-layer pure and iodine doped polystyrene system

The study has been made on 60 μm thick solution grown single and two-layer pure and iodine (I₂) doped polystyrene (PS) specimens. For two-layer samples, I₂-doped layer was solution grown on previously obtained undoped layer on glass substrate. The samples were vacuum aluminized over central circular area of 3.6 cm diameter on one surface, and then were thermally polarized at different temperatures (T_p) (i.e. 20, 75 and 100°C) with 100 kV/cm polarizing field. Initial charge density has been found to be of 10^-8 Coul/cm². The symbols (+) and (-) mean that positive and negative voltage were applied to the doped-layer side. For undoped and two-layer (+) the charge has always been found to be heterocharge. However, two-layer (-) are characterized with homocharge, when poled with high values of field and temperature