Characterization of melt-blown filters made of polypropylene and polypropylene-antimicrobial blends

Melt-blown filter media containing antimicrobial compounds were evaluated for mechanical properties, filtration efficiency, and ability to prevent bacterial growth on the filter. The filters were challenged with gram-negative and gram-positive bacteria grown on agar at three levels of pH and incubated at 25°C and 37°C for 24 h and 48 h. Antimicrobial Compound A prevented growth of the gram-positive Staphylococcus aureus bacteria at pH 4.8. Compound A was ineffective against the gram-negative Klebsiella pneumoniae bacteria at any pH. Compound B had no effect on bacterial growth. Compound C prevented growth of gram-negative and -positive bacteria at all pH levels. The antimicrobial compounds were nucleating agents, producing slight increases in crystallinity temperature, modulus, tensile strength, and stress-at-break and a decrease in elongation-at-break. Fiber diameter increased with increasing concentra-tions of antimicrobial compounds. Fil-tration efficiency decreased with increasing fiber diameter. Application : Fortification of polypropylene resin with antimicrobial compounds shows promise as a method for producing aseptic air filters.