Comparing the time invariant and time-variant dielectric relaxation data simulated for a macromolecule's growth

Abstract

The reliability of information obtained from dielectric data on the time-variant relaxation behaviour of a material has been examined. To do this, we first simulated the dielectric permittivity and loss data as a function of ac frequency for a series of time-invariant systems, which contained contributions from interfacial impedance, dc conductivity and dipolar relaxation, assuming that the static and high-frequency permittivities, the dc conductivity and the characteristic relaxation time change with time in a way that qualitatively agreed with those determined from experiments. These data were then transformed into sets of fixed frequency dielectric data as a function of time, and then analyzed pretending that the original parameters were unknown to us. The analysis gave parameters in reasonable agreement with those used for the simulation of the data. Thus, fixed frequency dielectric measurements on a time-variant system may be relied upon to yield information on the time-invariant states of the system, although, ideally speaking, measurement of time-invariant states would be desirable if errors arising from the interpolation needed to obtain the data for a time-invariant state could be eliminated.