Performance comparison of PVDF-based unimodal and bimodal electret air filters via solution-blowing and electro-blowing methods

Abstract

In this study, unimodal and bimodal PVDF nano/micro-fibrous filter mats are produced using electro-blowing (EB) and solution-blowing (SB) techniques. Fiber diameters are controlled by adjusting solution concentrations (10 and 20 wt%) and applying an electric field. Nanofibers from low-concentration solutions using EB averaged 236 nm, while fibers from high-concentration solutions via SB reached around 1 mu m. Both methods result in fiber bundles, with EB forming finer bundles and SB producing thicker ones. Defects such as droplets and beads are observed in SB, decreasing with the electric field and lower solution concentration. Bimodal mats show fiber distributions centered around 250 nm and 1 mu m. FTIR analysis reveals similar crystallization, with all samples dominated by the beta-phase and finer nanofibers increasing peak intensities. Filtration tests for PM0.3 at 15.83 cm/s show Sample A (EB) achieves the highest efficiency (95.95%) but also the highest resistance (250.33 Pa). Among bimodal samples, four-layered ABAB mats show the best quality factor (QF) with 84.67% efficiency and 145.25 Pa pressure drop, while Sample A + B achieves 88.24% efficiency with a lower pressure drop (169.50 Pa). Corona discharge treatment enhances filtration efficiency, with the sample ABAB reaching 94.55% efficiency and a 151.83 Pa pressure drop after treatment.