Average size nodule aggregates

Khayet et al. [31] studied the surfaces of asymmetric poly(etherimide) (PEI) ultrafiltration membranes by AFM. Membranes were prepared by casting mixtures of PEI, hydroxybutyric acid y-lactone (GBL, y-butyrolactone) as nonsolvent and N,N-dimethylacetamide (DMAc) at 50 °C. The average size of the nodule aggregates versus PEI concentration is given in Fig. 4.16. From Fig. 4.16, it is clear that the nodule aggregate diameter increases as the PEI concentration increases. 

Figure 24 shows top surface at the size of 1 pm. It seems that a supemodular aggregate contains nodules with average diameter of 43.7 nm. Table 14 includes the data on the dependence of roughness parameters on the scan size with respect to the same PPO-CS2 membrane. 

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