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Effect of surface charge density on electret filters charge degradation by organic solvent exposure

The effect of the surface charge density of an electret filter on its collection efficiency degradation via isopropyl alcohol (IPA) species exposure is discussed in this study. Five electret filters with different electrostatic properties and identical physical properties were prepared and exposed to IPA species. Furthermore, the filtration performance was evaluated. Filters exposed to IPA droplets showed a drastic reduction in the collection efficiency. In addition, the electret filter with a higher surface charge density had a higher tolerance to IPA droplets, that is, the challenged IPA droplet amount that neutralized the electret filter with a high surface charge density (= 5.0 × 10 -5 C/m 2 ) was 2.5 times higher than that of an electret filter with a low surface charge density (= 1.9 × 10 -5 C/m 2 ). The results of this study revealed that there was a positive relationship between the surface charge density and challenged amount required to neutralize an electret filter.