This article presents the formation of a dextran nanofibrous layer by needleless electrospinning. Optimum process parameters such as polymer solution and addition (surfactant) concentration, voltage, distance, etc. were determined to obtain uniform and smooth dextran nanofibers. It was not possible to produce nanofibers from pure dextran/water solution. Instead, solution drops were deposited on the collector; therefore, anionic surfactant was added in various concentrations to start the nanofiber production. Also, the effects of surfactant concentration on the solution properties, spinnability and fiber properties were determined. Generally, uniform and fine nanofibers were obtained from the rod electrospinning method. The value of 2 wt% surfactant concentration was chosen as the optimum concentration to produce a dextran nanofibrous layer by roller electrospinning. According to the results, spinning performance was 0.6726 g/min per meter, average fiber diameter was 162 nm, diameter uniformity coefficient was 1.03 and the nonfibrous area was 0.5%. In conclusion, this methodology resulted in the production of good product properties such as good spinnability, fine and uniform nanofibers and high fiber density.

In this study, definitions and explanations of the relationships between selected independent and dependent parameters of roller electrospinning are introduced. We aimed to define and completely analyze new parameters, such as the number of Taylor cones per square meter, the spinning performance for one Taylor cone, total spinning performance, fiber diameter uniformity coefficient and non-fibrous area percentage. Also, new measurement methods were developed and explained to analyze these parameters. According to the experimental results, strong and significant relationships between independent and dependent parameters of roller electrospinning were found. These independent and dependent parameters were affected by varying the concentrations of polyurethane and tetraethylammoniumbromide (TEAB) salt. In particular, the spinnability of the polymer solution, which is the most important factor for the roller electrospinning method, significantly increased with the TEAB concentration. If the spinning performance is positive, a specific solution is spinnable. However, the solution is not spinnable if the spinning performance is zero.

The electric currents between electrodes in the electrospinning process are based on the movement of charge carriers through the spinning space. The majority of the charge carriers are formed by ionization of the air close to the metallic needle and to the polymer jet. The salt contained in the polymer solution contributes to the concentration of charge carriers, depending on its amount. The conductivity of polymer jets does not significantly affect the current since the jets do not link the electrodes.

This paper discusses the effects of 1,1,2,2 tetrachlorethylen (TCE) non-solvent addition on the independent (electrical conductivity, dielectric constant, surface tension and the theological properties of the solution etc.) and dependent parameters (number of Taylor cones per square meter (NTC/m2), spinning performance for one Taylor cone (SP/TC), total spinning performance (SP), fiber properties such as diameter, diameter uniformity, non-fibrous area) in roller electrospinning of polyurethane (PU). The same process parameters (voltage, distance of the electrodes, humidity, etc.) were applied for all solutions during the spinning process. According to the results, the effect of TCE non-solvent concentration on the dielectric constant, surface tension, rheological properties of the solution and also spinning performance was important statistically. Beside these results, TCE non-solvent concentration effects quality of fiber and nano web structure. Generally high fiber density, low non-fibrous percentage and uniform nanofibers were obtained from fiber morphology analyses.

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