Conference Speakers

Eunkyoung Shim

Research Assistant Professor, North Carolina State University

BIOGRAPHY

Eunkyoung Shim is an Associate Professor at NC State University based in Raleigh, North Carolina. Previously, Eunkyoung was an Assistant Professor at NC State University. Eunkyoung received her Ph.D. degree from NC State University.

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Charge Protection in Electret Air Filtration Nonwoven Materials

Nonwoven media used as electret air filters are often embedded with charges to improve particle capture efficiency. These charged filters are invariably exposed to low surface tension fluids such as oils and alcohols leading to charge loss. In this study, we endow filtration media with charge protection through increased surface repellency using melt additives that can migrate to the surface during processing. Nonwovens containing fluorochemical melt additives are produced, and examined to determine the relationship between surface chemistry, isopropyl alcohol (IPA) repellency, resultant charge retention and filtration characteristics. We find surface fluorine/carbon (F/C) ratios of approximately 0.2 are sufficient to protect filtration performance from vapor discharging methods. Samples with bulk additive loadings of 1.2% or higher are found to achieve the necessary repellency to resist discharging independent of migration state of the sample, while samples loaded at the 0.6% level required sufficient migration to achieve the requisite F/C ratio of 0.2 in order to be protected. Samples which achieved the necessary surface chemistry to provide significant IPA repellency retained more than 80% of electret charge and corresponding filtration performance. These results have special significance in the design of filtration media relevant in global healthcare and other industrial settings.