Electrostatic investigation of charged nanoporous electret materials

The electret properties of nano and/or meso porous fluoropolymer mats and films, fabricated by impregnation and super-critical fluids (SCFs) method and charged by the corona method at ambient environment, are investigated. Positron annihilation lifetime spectroscopy (PALS) and small angle X-ray scattering (SAXS) are applied to study the charge characteristics of a free volume of electret polymeric materials. The topography and surface charges of electret polymeric materials are studied by electric field microscopy (EFM). The experimental results reveal that the nanopores and/or mesopores of the electret polymeric materials influence the retention and stability of charge. Aged surface charges were enhanced by more than ten times from comparisons with and without fluoro-polymer impregnation of the PP mat.