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Representative SEM micrographs of flat sheet membrane cross-sections and surfaces. (a, b, c) PX0, (d, e, f) PX10, (g, h, i) PX20, (j, k, l) PX40 and (m, n, o) PX60. Scale bars of left hand column represent 10 µm; scale bars of middle and right represent 50 µm.
