Abstract
Sorption and permeation behavior of CO~2~ and CH~4~ was examined in detail for a series of miscible blends based on bischloral polycarbonate (BCPC) and poly (methyl methacrylate) (PMMA). The former pure polymer exhibits decreases in the permeability coefficients for both CO~2~ and CH~4~ as the upstream driving pressure increased as predicted by the dualβmode sorption model. On the other hand, PMMA shows a decrease for CH~4~ but an increase for CO~2~. The latter is attributed to plasticization by this more soluble gas. The blends show intermediate behavior. CO~2~ permeation was examined on pressurization, at constant pressure for two weeks, and then on depressurization. The pattern of behavior progressively deviated between that of BCPC and PMMA as the MMA content of the blends was varied. These trends were contrasted with those previously described for a series of styrene/methyl methacrylate copolymers. Some differences in behavior between the blends and the copolymers were noted when compared at constant MMA content. These results have important ramifications for the design and selection of polymers for membranes to separate the CO~2~/CH~4~ gas pair.