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Polysulfone (PSU) is a popular material in microfiltration applications. In this study, the preparation of PSU membranes via electrospinning technology was investigated and optimized. Solutions with three different concentrations (15, 20 and 25 wt%) of PSU in dimethylformamide were electrospun at three different feed rates (1.5, 2.5 and 3.5 mL h−1) and voltages (12.5, 15 and 18 kV). The morphologies of the samples were studied using SEM. The results showed that the samples prepared from a 15 wt% solution concentration have beads‐on‐string morphologies. As the solution concentration is increased to 20 and 25 wt%, the beads disappear and uniform fibers with average diameters ranging from 0.876 to 2.078 μm depending on the voltage and the feed rate are obtained. The optimum electrospinning conditions for the highest wettability with minimum operating pressure were predicted to be a solution concentration of 25 wt%, a feed rate of 3.5 mL h−1 and a voltage of 18 kV. The prediction was verified by contact angle test measurements and filtration experiments. © 2019 Society of Chemical Industry

In this study the electrospinning of polyvinyl alcohol (PVA) was evaluated and optimized for minimum fiber diameter following Taguchi methodology. The effect of four factors including the solution concentration, voltage, flow rate and needle-collector distance each at 3 levels on fiber diameter were investigated. The morphology and the diameter of the fibers were studied by a scanning electron microscope. It was found out from the main effects and the analysis of variance that in the range of levels studied concentration is the most influencing factor on the fiber diameter with a contribution of 89.22 %. Voltage makes a minor contribution of 10.028 % and the flow rate and distance have negligible influence (less than < 1 %). The minimum fiber diameter was predicted to be 381 nm and to be achieved at the combination of concentration of 8 wt.% PVA, voltage of 18 kV, flow rate of 0.7 cm3/h and the distance of 10 cm. Validation experiment resulted in fibers with 390 nm diameter which is in close agreement with the predicted value by the Taguchi technique.

Bead‐on‐string is a desirable morphology for some emerging applications of electrospun mats such as superhydrophobic surfaces. In this study, the bead‐on‐string morphology in electrospun polysulfone (PSU) mats was investigated and correlated with the solution concentration, voltage and feed rate. PSU/dimethylformamide solutions with different concentrations (4, 5.5, 7, 15, 18 and 20 wt% PSU) were electrospun at a constant feed rate (3.5 mL h–1) and voltage (15 kV). Critical chain overlap and entanglement concentrations were found to be 3.65 and 7.12 wt% PSU, respectively. The bead‐on‐string morphology was detected in the concentration range 7–18 wt% PSU, in close agreement with theoretical estimations. The evolution of the bead‐on‐string morphology in mats prepared from 15 wt% PSU solution and electrospun at three feed rates (i.e. 1.5, 2.5 and 3.5 mL h–1) and voltages (i.e. 12.5, 15 and 18 kV) were also studied. The results showed that the beads appear less in number as either the feed rate or the voltage increases. In addition, the morphology of the beads revealed a transition from a spherical to a spindle‐like appearance with an increase in voltage. The effect of feed rate on bead geometry, however, was revealed to depend on the applied voltage. © 2020 Society of Chemical Industry