Effect of corona charging, additives and processing conditions on the barrier and filtration properties of polypropylene melt-blowns

Abstract

Air pollution and airborne pathogens pose significant risks to public health and well-being. Electret melt-blown filters with high filtration efficiency (FE) and low-pressure drop (PD) are used to prevent inhalation of these pollutants. Melt-blown polypropylene (PP) electret filters offer an attractive combination of fine-fiber structure and electrostatic particle capture but often provide limited charge stability and inconsistent performance. In this study, we investigated the combined effects of corona charging, magnesium stearate (MgSt) additive loading, and melt-blown processing conditions on the filtration behavior and long-term stability of PP melt-blown. Melt-blown webs were produced using controlled variations in air pressure, die-to-collector distance (DCD), and MgSt concentration (0–2 wt%), followed by corona treatment at −50 kV. The incorporation of MgSt significantly increased the surface charge density, leading to substantial improvements in post-charging filtration efficiency (FE). All charged samples achieved FE values exceeding 98% at 32 L min⁻¹, with quality factor (QF) values improving by 2–5 times compared to uncharged webs. Samples containing 1 wt% MgSt exhibited the optimal balance of FE, pressure drop (PD), and electret stability, demonstrating minimal performance decay over 60 days. Structural analysis using scanning electron microscopy (SEM), porometry, differential scanning calorimeter (DSC), and X-ray diffraction (XRD) revealed that MgSt acted as a heterogeneous nucleating agent, increasing crystalline interfaces and enabling deeper charge-trap formation. These findings indicate that the combination of MgSt with optimized processing and corona charging offers a practical route to produce high-efficiency, low-resistance melt-blown electret filters with improved long-term performance.