Effect of blown air temperature on morphology, phase structure and filtration efficiency of PVDF nanofibrous mats produced via electro-blowing

Abstract

This study investigates the effects of temperature of pressurized blown air on fiber morphology, porosity, phase structure, and filtration performance of PVDF nanofibers produced via the electro-blowing method for the first time. The blown air heated to 20, 40, 60, and 80°C was utilized during production. Increasing air temperature resulted in more homogeneous distribution of fibers and defect-free fibrous mats, accompanied by a significant reduction in fiber diameter. A linear relationship between fiber diameter and pore size was observed; as fiber diameter decreased, reducing air permeability due to smaller pore sizes. FTIR measurements revealed the highest β-phase content (82%) in the PVDF-80C sample produced at 80°C. The rise in temperature lowered solution viscosity and surface tension, contributing to improved drawing effect and therefore higher β-phase content in the PVDF polymer. Corona discharge treatment further enhanced the surface potential, with the finest fibers exhibiting the highest surface charge. The PVDF-80C sample demonstrated the best performance during filtration tests against NaCl aerosols (PM0.3) at a flow rate of 95 L/min, achieving a filtration efficiency of 98.68% with a pressure drop of 153 Pa. These findings highlight the critical role of temperature in influencing nanofiber properties and filtration performance. Highlights: Finer fibers and defect-free mats achieved with increased air temperature. PVDF-80C showed 82% β-phase content, the highest among all samples. Smaller fiber diameter led to reduced pore size and lower air permeability. Corona discharge enhanced surface potential, boosting fiber charge. PVDF-80C achieved 98.68% filtration efficiency with 153 Pa pressure drop.