Langmuir sorption capacity

FIGURE 9.4 Dependence of constants (a, b, and c present Henry constant, sorption affinity constant, and Langmuir sorption capacity respectively) of the model of dual-mode sorption of hydrocarbons by glassy polyphenylene oxides on boiling temperatures of hydrocarbons Z), is pDMePO, poly-2,6-dimethyl-l,4-phenylene oxide o is pDPhPO, poly-2,6-diphenyl-l,4-phenylene oxide is pDMePO/pDPhPO copolymer (97.5/2.5% mol) v is pDMePO/pDPhPO copolymer (75/25% mol). (From analysis of results presented in Lapkin, A.A., Roschupkina, O.P., and Ilinitch, O.M., J. Membr. Sci., 141, 223, 1998.)... 

FIGURE 20.4-7 Langmuir sorption capacity C as a function of temperature for several polymer-penetrant syatems. Note diet C disappears near Tg in the same fashion as Vg — Vt does in Fig. 20.4-5.26... 

Langmuir Sorption Capacity of Glassy Polymare. J. Polym. Sci. Polym. Phys. Ed., 19, 1655 (1981). 

FIGURE 20.4 7 Langmuir sorption capacity as a fimciion of temperature forseveral polymer-penetrant... 

Free Volume. The Langmuir sorption capacity, C , of the dual-mode sorption model 12 J 3) characterizes gas sorption in the non-equilibrium excess fiee volume of a glassy polymer. The total sorbed gas concentration in a glassy polymer, which is a summation of Henry s law dissolution (C ) and Langmuir type hole filling (C, ), is given by ... 

When the aging protocol includes themn annealing at various temperatures, the same trend in C is observed (4), That is, both gas permeability and C of PTMSP are reduced by thermal treatment (4). Furthermore, aging-induced decreases in gas permeability of PTMSP synthesize using various catalysts are correlated systematically with changes in Therefore, aging appears to reduce the nonequilibrium excess free volume of PTMSP which, in turn, reduces the Langmuir sorption capacity and the gas permeability. 

C -.Langmuir sorption capacity cm STP/cm polym. kp Henry s law solubility coefficient cm STP/ (cm polym. cmHg). b affinity constant of Langmuir site cmHg... 

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