Relative penneability

Figure 20.9. Predicted gas permeability of composites containing perfectly aligned disk-like filler particles, relative to that of the matrix polymer. The number in each curve label denotes the filler volume fraction d>. Results obtained by using the analytical equation of Fredrickson and Bicerano [60] are compared with results obtained by the numerical simulations of Gusev and Lusti which suggest that relative penneability is a function of the product 0-Af [61].

FIGURE 20.4-14 Demonstration of the flux-depiessing effect of low relative humidities on the CO2 penneability of Kapton polyimide. Paulson et al. has shown that at high relative humidities, the observed flux of CO2 in a number of polymers is higher than the pure component level. At much higher relative humidities for Kapton, it may be that this effect also will be observed, consistent with the right-hand side of Fig. 20.4-4. 

Note Column A = Column B -I- C and Column D = Column E + F. The reductions (%) in the table refer to changes relative to the values tabulated under the pure component penneability columns in Table 20.4-6. Separation factor reductions refer to changes relative to the pure component permeability ratios of CO and CH, tabulated in the pure component columns in Table 20.4-6. As noted earlier, for plasticization-prone polymers such as cellulose acetate, massive flux increases can be observed in the presence of a strongly interacting gas such as CO2 in mixed gas situations. Such plasticization is generally undesirable because it produces losses in selectivity. 

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