The functional principle is consistent with that of an impedance measurement. In a typical test, the sample is placed in contact with two electrodes (the dielectric sensor).
When a sinusoidal voltage is applied, the charge carriers inside the sample are forced to move: positively charged particles migrate to the negative pole and vice versa. This movement results in a sinusoidal current with a phase shift.
In the frequency range of theDEA 288 Ionic (up to 1 MHz), the charge carriers are mainly ions (often present as catalysts or impurities) and additionally dipole alignment takes place within the electrical field.
The response signals – current and phase shift – are a function of the ion and dipole mobility. This relationship makes dielectric (thermal) analysis an ideal method for monitoring a curing process, where the sample's viscosity is increasing dramatically. As a consequence, the mobility of the charge carriers decreases, causing a corresponding attenuation of the amplitude and an increased phase shift in the resulting signal.