Fecha de publicación: 21/12/2024 Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE The electrospinnability of PVDF nanofiber membranes was refined to obtain bead-free fibers with an enhanced crystalline β phase. The improved morphology and posterior surface charge induction boosted electrostatic filtration performance, surpassing that of commercial HEPA filters. This method provides a reliable approach for developing high-performance membranes to address the growing demand for efficient ultrafine particle filtration.

ABSTRACT
This study successfully refined the electrospinnability window for polyvinylidene fluoride (PVDF) nanofiber membranes by systematically investigating solvent systems to achieve bead-free morphologies mapped within a Teas ternary diagram. The correlation between fiber morphology and solution properties, such as viscosity, surface tension, and conductivity, allowed for a reproducible approach to fabricate high-performance nanofiber membranes. Using DMSO:Ac/60:40 solvent ratio and a 14% w/w PVDF concentration, following a 32 factorial DoE, bead-free fibers with an average diameter of ~700 nm were produced. This solvent selection and morphology refinement enhanced the crystalline β phase, which promoted intern-oriented dipoles that were enhanced by an additional charge induction effect. This led to increased volume and surface charges on the membrane, enhancing electrostatic filtration mechanisms. Filtration tests at a 5.3 cm/s face velocity showed that a 10.4 g/m2 bead-free PVDF fiber membrane enriched with a β phase and additional induced surface charge, outperformed bead-on-string structures and a commercial high efficiency particulate air (HEPA) filter, achieving HEPA-grade efficiencies ηMPPS=0.995andηPM0.3=0.998$$ \left({\eta}_{MPPS}=0.995\ \mathrm{and}\ {\eta}_{PM0.3}=0.998\right) $$ with low air resistance ΔP=112.7Pa$$ \left(\Delta \mathrm{P}=112.7\ \mathrm{Pa}\right) $$. These results highlighted the role of morphology and charge characteristics in filtration efficiency and provided a method for PVDF electrospinning to meet the growing demand for effective ultrafine PM filtration.