When the PVA content was increased to
3%, the as-spun nanofibers were relatively uniform (Fig. 2d);
nanofibers with 4% PVA showed even better characteristics
(Fig. 2e) because the size distribution of the as-spun nanofibers
was uniform. As PVA content increased, the diameters of the asspun
fibers also increased, as shown in Fig. 2f.