Figure 3: Surface and section SEM micrographs of PSf/PAA 96/04 at different precoagulation drying time: (a, A) 10 sec, (b, B) 300 sec and (c, C) + ∞, respectively. The magnification of surface images is 500X whereas that of section images was 200X. The concentration of initial PSf/DMF solution was 19% (wt).