Thermally stimulated depolarisation current calculated from isothermal dielectric response functions

Thermally stimulated depolarisation (TSD) currents are modelled from dielectric response functions deduced from isothermal measurements. The key assumption is that the same state of polarisation can be achieved both via the real non-isothermal TSD process or via an equivalent isothermal process. The change of polarisation with temperature and time is traced through a continuous adjustment of the starting and stopping times and polarising field of the fictitious isothermal process. The theory is applicable to general non-Debye relaxation and variable activation energies. A comparison is made with experimental data on polyethylene terephtalate films