New Apparatus for Measuring the Complex Dielectric Constant of a Highly Conductive Material

Difficulties in measuring the contplex dielectric constant of a highly conductive material such as aqueous polyelectrolytes including biopolymers arise from (l) electrode polarization effect and (2) d.c. conductance of the specimen which is very much higher than the conductance due to dielectric loss and drifts with time. A new method has been developed in which the first difficulty is avoided by employing a four-electrode cell and the second orue is overcome by direct measurement of the frequency difference spectrum of specimen impedance, Δ Z (ω)= Z (ω)- Z (ω 0 ), between the measuring frequency ω and the reference ω 0 . By this procedure, the effect of frequency-independent d.c. conductance is eliminated. With the new method, the frequency range of dielectric measurement is extended from 0.2 Hz to 30 kHz.