Effect of electrospinning conditions on β-phase and surface charge potential of PVDF fibers

• Published in: Polymer (Guilford) 2021-07, Vol.228, p.123902, Article 123902
• Main Authors: Gade, Harshal, Nikam, Shantanu, Chase, George G., Reneker, Darrell H.
• Format: Article
• Language: English
• Subjects: Beta phase; Diameters; Electrets; Electrospinning; Faraday Bucket; Fibers; Flow rates; Flow velocity; Fluorides; Polymers; Polyvinylidene fluorides; PVDF; Rotation; Surface charge; Weight
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2021.123902

Electrospun polyvinylidene fluoride (PVDF) fibers, can act as electrets in filtration applications. Relevant to this is the extent at which electrospinning conditions affect the beta-phase content of PVDF fibers. The beta-phase content is a strong factor in measured charge potentials on PVDF fiber mats. PVDF fiber mats were electrospun from three different polymer solution concentrations (10, 14 and 18 wt%) to fabricate mats of three average fiber diameters (328, 780, 1167 nm) respectively and of five different basis weights (10, 20, 30, 40, and 50 g/m2). Furthermore, fiber mat samples were electrospun at varying conditions of applied voltage (21, 24, 27 and 30 kV), solution flow rates (2, 5 and 8 ml/h), needle-tip to collector distances (12, 15, 18, 22 cm) and collector drum rotation speeds (5, 45, 100 rpm) while holding constant the 10 wt% solution concentration and 20 g/m2 mat basis weight. SEM images and FTIR spectra were analyzed to estimate the average fiber diameter and amount of beta-phase content. The apparent surface charge potential was measured using a custom-made Faraday Bucket. The solution compositions, flow rates, and needle-tip distance had moderate effects on fiber diameters and on the beta-phase content. The measured surface potential was found to be directly proportional to beta-phase content. The rotation rate of the drum collector had negligible effect on fiber diameter but did affect the beta-phase and surface potential. The measured surface charge potential was directly proportional to the basis weight and inversely proportional to the fiber diameter. [Display omitted] •Electrospun PVDF with variations in potential, distance, concentration, flow rate, and rotation rate.•Fiber mats properties: fiber diameter 200–1300 nm, beta-phase 85–93%, and charge 800–4000 V/g.•Polymer concentration had largest impact on fiber diameter.•Flow rate and distance affected beta-phase content.•Mat potential (V/g) was fitted to empirical correlation.