Correlation between charge decay and solvent effect for melt-blown polypropylene electret filter fabrics

• Effect of solvents on filtration action of melt-blown PP electret fabrics was studied.
• Degradation of filtration action is correlated to solubility parameter of solvents.
• Smaller solubility parameter difference between PP and solvent cause greater decay.
• Results are explained according to Flory–Huggins solvent swelling theory

Melt-blown polypropylene electret fabrics are widely used as air filter media. However, its filtration efficiency gradually decays in application process. This paper is to investigate the correlation between filtration efficiency decay and solvent effect. Experimental results show that filtration efficiency displays a regular decrease when polypropylene electret fabrics are exposed to solvents in the sequence of water, ethanol, isopropanol and acetone. The results can be correlated to solubility parameter difference between polypropylene and solvent according to the Flory–Huggins swelling theory. Smaller solubility parameter difference leads to greater decay of filtration efficiency owing to greater affinity between polypropylene and solvent.