Effect of Solvent Exposure on the Filtration Performance of Electrostatically Charged Polypropylene Filter Media

Abstract

Solvent-induced performance deterioration in corona charged polypropylene electret filter media was studied. Electret media, exposed to isopropanol (IPA) in the liquid phase, exhibited reduced filtration efficiency with negligible changes in the pressure drop across the media. Scanning electron microscopy imaging indicated no observable morphological changes after IPA exposure. Solvent-induced efficiency deterioration of electret filter media was hypothesized to originate from charge deterioration rather than charge masking. The charge of the individual fibers in filter media was characterized using electrostatic force microscopy (EFM). EFM investigation produced evidence that exposure to IPA in the liquid phase affected the electrostatic charges on fibers. Exposure to organic solvents such as xylene, toluene, and ethyl benzene has been reported to increase charge mobility in polypropylene fibers, thereby reducing the electrostatic charge and the ability of the fibers in the electret filter media to capture particulates.

Keywords

electret filter media electric force microscopy filtration

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References

Chen, C. , Lehtimäki, M. , and Wileke, K. , Loading and Filtration Characteristics of Filtering Facepieces , Am. Ind. Hyg. Assoc. J. 54, 51-56 (1993).

Chen, C.C. , and Huang, S.H. , The Effect of Particle Charge on the Performance of a Filtering Facepiece , Am. Ind. Hyg. Assoc. J. 59, 227-233 (1998).

Jasper, W. , Hinestroza, J. , Mohan, A. , Kim, J. , Shiels, B. , Gunay, M. , Thompson, D. , and Barker, R. , Effect of Xylene Exposure on the Performance of Electret Filter Media , J. Aerosol Sci. 37, 903-911 (2006).

Kim, J. , Jasper, W. , and Hinestroza, J. , Direct Probing of Solvent Induced Charge Degradation in Polypropylene Electret Fibers via Electrostatic Force Microscopy , J. Microsc. 20, 1-8 (2007).

Kim, J. , Jasper, W. , and Hinestroza, J. , Charge Characterization of an Electrically Charged Fiber via Electrostatic Force Microscopy , J. Eng. Fibers Fabrics 1, 30-46 (2006).

Lehtimäki, M. , and Heinonen, K. , Reliability of Electret Filters, Build . Environ. 29, 353-355 (1994).

Lowkis, B. , and Motyl, E. , Electret Properties of Polypropylene Fabrics , J. Electrostatics 51, 232-238 (2001).

Martin, S.B. , and Moyer, E.S. , Electrostatic Respirator Filter Media: Filter Efficiency and Most Penetrating Particle Size Effects , Appl. Occup. Environ. Hyg. 15, 609-617 (2000).

Schurmann, G. , and Fissan, H.J. , Fractional Efficiencies of an Electrostatically Spun Polymer Fiber Filter , J. Aerosol Sci. 15, 317-320 (1984).

10.

Biermann, A. , Lum, B. , and Bergman, W. , Evaluation of Permanently Charged Electrofiberous Filters , in "Proceedings for 17th DOE Nuclear Air Cleaning Conference" (1982).

11.

Cantaloube, B. , Dreyfus, G. , and Lewiner, J. , Vapor-induced Depolarization Currents in Electrets , J. Polym. Sci. Polym. Phys. Ed. 17, 95-101 (1979).

12.

Rychkov, A.A. , Cross, G.H. , and Gonchar, M.G. , A Method for Discriminating between 'External' and 'Internal' Processes Leading to Voltage Decay from Electrets in Humid Conditions , J. Phys. D Appl. Phys. 25, 522-524 (1992).

13.

Tsai, P.P. , Schreuder-Gibson, H. , and Gibson, P. , Different Electrostatic Methods for Making Electret Filters , J. Electrostatics 54, 333-341 (2002).

14.

Bonnell, D. , "Scanning Probe Microscopy and Spectroscopy," Wiley-VCH , New York, USA (2000).

15.

Oksana, C. , Chen, L. , Weng, V. , Yuditsky, L. , and Brus, L. , Quantitative Noncontact Electrostatic Force Imaging of Nanocrystal Polarizability , J. Phys. Chem. B 107, 1525-1531 (2003 ).

16.

Said, R.A. , Perturbation Detection of Electric Force Gradients using the Phase Shift Method , J. Phys. D Appl. Phys. 34, L7-L10 (2001).

17.

Sarid, D. , "Scanning Force Microscopy," Revised Edn., Oxford University Press, New York, USA ( 1994).

18.

Code of Federal Regulations Title 42, Part 84, Respiratory Protective Devices Final Rules and Notice, Department of Health and Human Services, Public Health Services (1995).

19.

Sacha, G.M. , and Saenz, J.J. , Cantilever Effects on Electrostatic Force Gradient Microscopy , Appl. Phys. Lett. 85, 2610- 2612 (2004).

20.

Bachtold, A. , Fuhrer, M.S. , Plyasunov, S. , Forero, M. , Anderson, E.H. , Zettl, A. , and McEuen , P.L. , Scanned Probe Microscopy of Electronic Transport in Carbon Nanotubes , Phys. Rev. Lett . 84, 6082-6085 (2000).

21.

Lei, C. , Das, A. , Elliott, M. , and Macdonald, J. , Conductivity of Macromolecular Networks Measured by Electrostatic Force Microscopy , Appl. Phys. Lett. 83, 482-484 (2003).

22.

Lei, C. , Das, A. , Elliott, M. , and Macdonald, J. , Quantitative Electrostatic Force Microscopy-phase Measurements , Nanotechnology 15, 627-634 (2004).

23.

Gomez-Monivas, S. , Froufe-Perez, L.S. , Caamano, A.J. , and Saenz, J.J. , Electrostatic Forces between Sharp Tips and Metallic and Dielectric Samples , Appl. Phys. Lett. 79, 4048- 4050 (2001).

24.

Forsythe, W.E. , "Smithsonian Physical Tables," 9th Revised Edn., Knovel, New York, USA (2003).

25.

Gokel, G.W. , "Dean's Handbook of Organic Chemistry," 2nd Edn., McGraw-Hill, New York, USA (2004).