ABSTRACT
In addition to the electrospinning process, the fiber morphology was also affected by the applied voltage. The SEM images of nanofibers electrospun by the cylinder spinneret (cylinder diameter = 80 mm, fillet radius = 2 mm) from 9.0 wt% PVA solution under different applied voltages are shown in Fig. 4.2. The average fiber diameters calculated based on SEM images are given in Fig. 4.3a. For the cylinder electrospinning system, the electrospinning distance ranging from 11 to 15 cm was trialed. A shorter spinning distance led to wet fibers which merged into a polymer film on the collector, while a longer spinning distance resulted in stoppage of electrospinning because of the declined electric force. Nanofibers electrospun from 9 wt% PVA solution showed a bead-free fibrous structure. When the applied voltage was in the range of 47-62 kV, the average fiber diameters were very similar with a wide diameter distribution.
