Supemodular aggregate

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. 

Unlike PPO-CS2 membrane no super nodular aggregates were found on the surface of PPO-CeHe membrane (Figure 25). Among PPO membranes cast from solutions of five different solvents, PPO-CS2 was the only membrane on the surface of which the supemodular aggregates were observed. 

The mean size of these supemodular aggregates is 890 nm. Inside the supemodular aggregates, there are nodules. The sizes of nodules and supemodular aggregates increased with an increase in the thickness of the membrane. Thus, a minimum in the nodule size was observed in a thickness range 9 to 11 pm. Figure 32, I shows the effect of the thickness of the membrane on the mean size of the nodules. Similar behaviour was also observed when the membranes were cast from a 0.5 wt. % PPO solution in TCE (Fig. 32, II). 

Table 18 shows the mean width and length of the gap between supemodular aggregates and nodular aggregates inside the supemodular aggregates for each plasma etching time in PPO-CS2 membrane. It is clear... 

Table 18. Mean width and length of the gap between supemodular aggregates, A, at 5 pm scan range and those of the gap between nodular aggregates, B, at 1pm range in the PPO-CS2 membrane after various plasma etching times ...

Figure 38. Arrangement and size of supemodular aggregates and nodule aggregates in dense PPO-CS2 membrane.

The distance between supemodular aggregates and nodular aggregates increases as the distance from the membrane surface to the depth direction increases. 

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