[Effect of biological fluids on the electrostatic properties of polyester foil electrets]

Thermoelectrets of "Hostaphan" polyester foil in two biological liquids, plasma and Ringer liquid, were investigated. Electrostatic parameters of the specimen immersed in the liquids at 37 degrees C as a function of the immersing time were studied. The following parameters were measured: the surface charge density, the excess charge, the polarization and the surface charge distribution along the specimen diameter before and after the immersing in the liquids. From the thermostimulated depolarization studies it appeared that, due to the immersing in the liquids, the charge is removed from the specimen surface, but stays in the bulk.