Study of the Influence of Electrospinning Parameters on the Structure and Morphology of Polyvinyl Alcohol Nanofibers

The paper presents the influence of some parameters involved in needleless electrospinning technology on the structure and morphology of polyvinyl alcohol nano fibers. Based on theoretical and practical aspects of the nanofibers obtained by needleless electrospinning technology and of the polyvinyl alcohol characteristics, were determined the areas of polymer concentration and the characteristics of the applied voltage, involving an electrospinning device equipped with a rod spinning electrode with a diameter of 8 mm and a lenght of 170 mm. The applied voltage to the rod spinning electrode was between 0-40 kV, domain in which the influence on the elongation level of the jet can be felt, with a direct action on the surface morphology of the nano fibers and on the relaxation time of the polymer, respectively. Regarding the concentration of polyvinyl alcohol aqueous solution, it was found that using low concentrations (5% wt), no matter what the value of the voltage is, instead of nano fibers droplets are formed and the electrospraying process appears. Instead, increasing the solution concentration causes a fusion of the droplets in nano fibers. Because droplets modified from spherical to spindle-like form and the distance between droplets increases with increasing viscosity, uniform nano fibers with larger diameters can be obtained. The range of concentrations where uniform nano fibers can be obtained, without beads on the surface, is between 10% wt and 16% wt polyvinyl alcohol in water.