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ABSTRACT:Three peaks, namely, {3, !X, and p peaks, have been observed in the TSD spectra of commercial polystyrene (PS) at about 338, 368, and 418 K respectively. Their origin is due respectively to the trapping of charge carriers by the particular atoms or molecules pressent in the amorphous regions of polystyrene, to the segmental motion of main chains, and to the accumulation of space charges at the crystalline and amorphous interfaces. Doping of polystyrene with chloranil [electron affinity 1.4eV (2.24 x 10-19 J)] has been found to form charge-transfer complexes. This probably involves three mechanisms: increase in the mobility of charge carriers, reduction in the trapping sites for charges, and provision of conductive path ways for them through the crystallineamorphous interfaces.KEY WORDSThe thermally stimulated discharge (TSD) current technique has been widely applied to a number of inorganic and organic compounds, but its application to polymers has been rather limited. Since TSD is governed by relaxation phenomena specific to the polymers, it can be used to study molecular motions in them at low frequency, a study which is of paramount interest for several applications. This paper reports a systematic study of TSD of pure as well as of chloranil-doped films (about 25 .urn thick) of polystyrene grown from solutions. The method is based on the measurement and interpretation of the discharge current which is generated on heating a polarised specimen (electret). were seen to give erroneous and nonreproducible results. Doping was done with chloranil by dissolving PS and chloranil together in cyclohexanone at room temperature over a period of days. It was found that doping takes about a week to complete. Three different concentrations of dopant, viz., 0.25, 1, and 4% by weight, were used. Films of doped PS were also prepared in the same manner as those of pure PS.Vacuum deposited silver electrodes were used for the measurement in sandwich configuration. While the lower electrode was deposited on the glass slide itself before dipping it in the solution, the upper electrode was deposited over the film when it was completely dried. Figure 1 gives the geometry of the sandwich configuration of film and electrodes together. A piece of teflon was used to insulate the upper electrode from the glass slide so as to eliminate any possible leakage of current through the slide. Contacts were made by gently pressing two copper discs, as shown in Figure 1. In this way a pressureless contact was achieved. Current was measured with an electrometer amplifier supplied by M/S. Electronic Corporation of India Ltd.; this was carefully shielded and grounded. Before measurement, the films were kept short circuited in a desiccator for about 24 h.