Thermally stimulated polarization and temperature dependence of equilibrium polarization in polymers

The theoretical formulation of thermally stimulated depolarization currents (TSDC) of dipolar systems is usually restricted to the case that the equilibrium polarization Pe depends on the temperature according to the Langevin function and that this temperature dependence can be neglected during the nonisothermal step of the poling process (i.e., the frozen-in polarization of the sample before a TSDC experiment is started is considered as equal to the equilibrium polarization obtained at the polarizing temperature T
p
).
¹
For a single relaxation time, this leads to the familiar Bucci-Fieschi equation representing an asymmetrical “glow curve,” the area of which can then be directly related to relaxation parameters such as dipole moment and dipole density.
²
With the same basic assumptions, the classical theory of thermally stimulated polarization currents (TSPC) provides for obtaining current peaks characterized by the same position, height, and shape as the corresponding TSDC peaks, the only difference being that the polarization current is of opposite sign.