Critical Evaluation: Carbon dioxide with Polyimide Kapton H (IUPAC SDS Volume 70)
Sorption of carbon dioxide in poly(4,4'-oxydiphenylene pyromellitimide) known under trademark Kapton H was studied in a number of works.1-6 The majority of researchers dealt with commercial samples of this material. Only Okamoto et al.5 investigated the specimens of this polymer prepared in the laboratory by imidization at different temperatures. The parameters of sotption isotherms obtained for this material differ from those measured for Kapton H. The table shows the selected dual mode sorption parameters for the system Kapton H-CO2. It is seen that smooth temperature dependence is observed for all three model parameters and for the apparent solubility coefficient S.
A larger scatter is observed for the affinity parameter b especially at lower temperatures. The enthalpies corresponding to van't Hoff plots of kD, b, and S are as follows:
ΔHD = -11.3 kJ/mol
ΔHH = -11.9 kJ/mol ΔHS = -25.1 kJ/mol.

The Langmuir capacity parameters decrease with temperature. It is noteworthy that temperature dependence is strongly nonlinear, so it is difficult to determine the temperature at which C'H vanishes. However, it is probably lower than the glass transition temperature of this polymer for which the values higher than 600 K2,3 and even 780 K have been reported.

Dual mode sorption parameters for the system Kapton H-CO2
C T (K) D β (cm3(g) cm-3(s) atm-1) D H D C'H (cm3/cm3) D b (atm-1)
308.0 7.6 5.94 x 10-1 23.5 3.00 x 10-1
323.0 5.9 6.30 x 10-1 13.3 3.94 x 10-1
323.0 6.0 6.50 x 10-1 12.8 4.2 x 10-1
353.0 2.5 4.36 x 10-1 8.5 2.39 x 10-1
353.0 2.4 4.0 x 10-1 8.9 2.3 x 10-1
383.0 1.3 2.8 x 10-1 6.1 1.6 x 10-1
383.0 1.2 2.92 x 10-1 5.7 1.53 x 10-1

References:

1 Hachisuka, H.; Tsujita, Y.; Takizawa, A.; Kinoshita, T.; Polym. J. 21, 681 (1989).
2 Tanaka, K.; Kita, H.; Okamoto, K.; Japan - US Polymer Symposium, p. 249-250 (1985).
3 O'Brien, K. C.; Koros, W. J.; Husk, G. R.; Polym. Eng. Sci. 27, 211 (1987).
4 Okamoto, K. I.; Tanaka, K.; Yokoshi O.; Kita, H.; J. Polym. Sci. B: Polym. Phys. 27, 643-654 (1989).
5 Chern, R. T.; Koros, W. J.; Yui, R.; Hopfenberg, H. B.; Stannett, V. T.; J. Polym. Sci., Polym. Phys. Ed. 1984, 22, 1061.
6 Uragami, T.; Hopfenberg, H. B.; Koros, W. J.; Yang, D. K.; Stannett, V. T; Chern, R. T.; J. Polym. Sci. B: Polym. Phys. 24, 779 (1986).