With increasing PVDF concentration, the fibers were turnedmore uniformly and with a lower breakpoint, and their diameters increased gradually. At the concentration of 12%, net structured fiber membranes were obtained with every fiber straight and closely packed. The volume ratio of DMF and acetone has negligible influence on the morphology of PVDF fibers [24]. The PVDF solution with the concentration of 12% with DMF/acetone ratio of 8:2was accordingly chosen for convenience of comparison in further experiments.