EVIDENCE FOR ELECTRET POLARIZATION IN POLYOXYMETHYLENE

It has been found that under certain experimental conditions, polyoxymethylene films undergo a microscopic as well as macroscopic polarization resulting in electret formation. Thermally stimulated discharge (TSD) currents have been measured for polyoxymethylene film electrets of 100 uM prepared at various polarizing fields and polarization temperatures. Experimental evidence like the shift of the discharge current peak with polarization temperature, and a nonlinear dependence of the accumulated charge on field strength suggests the formation of a space charge and interfacial polarization. The observed TSD peak at 130°C coincides with the a -relaxation temperature in low-frequency dielectric measurements. Activation energies and relaxation times have been calculated on the basis of the experimental data. © 1979, Taylor & Francis Group, LLC. All rights reserved.