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.
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