Abstract
Chitosan nanofibers were prepared via electrospinning by varying solution concentration (1, 2, 3, 4 and 6 wt %), applied voltage (14, 18 and 22 kV), flow rate (0.4 mL/h and 0.8 mL/h), needle diameter (0.2 mm and 0.8 mm) and distance between needle tip and collector (100 mm and 140 mm). No electrospinning was observed for 1-3 wt% samples, where as improved physical texture, decrease in the number and size of the beads and microspheres (in case of 4 wt%), and beads free nanofibers were obtained when the concentration of solution was changed from 4 to 6 wt%, applied voltage, flow rate and needle diameter from 14 kV, 0.4 mL/h, 0.2 mm to 22 kV, 0.8 mL/h and 0.8 mm, respectively. Increase in the polymer concentration has increased the viscosity of the solution to a critical value, higher voltage overcame the surface tension of the polymer solution, changes in the flow rate increased the flow rate above the threshold and change in needle made the diameter large enough to avoid evaporation of solvent at the needle tip, its blocking and allow the formation of jet. The effect of solution flow rate, distance between the needle tip and collector, and needle diameter on the morphology of nanofibers was observed only in case of 4 wt%. In all three cases the number and size of the beads decreased.