Polarization effects in polymer dielectrics: Theoretical modeland experimental results

The voltage decay response as a function of time after open circuiting a fully charged capacitor containing a molecularly polarized dielectric media was examined in an equivalent circuit representation. The equivalent circuit involves: the resistance (R) of the dielectric as a circuit element representing leakage effects; the capacitance (C) of the dielectric for characterizing the time dependence of the RC discharging circuit effect; and a black box (K) for representing the time dependence of the molecular polarization effects in the dielectric. From this equivalent circuit representation, the voltage decay due to leakage current, capacitive discharging, and polarization effects was found to obey a power law time dependence characterized by a CK time factor which is added to the open circuit run time (t) where this sum is raised to a negative K/R power: V = Va [CK]K/R [CK + t]−K/R This predicted power law time dependence was examined experimentally using several simple and composite polymer dielectrics, and the results were generally consistent with the predicted behavior particularly for the simple polymer dielectrics.