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(442e) Pure and Mixed-Gas Permeation Study Of Thermally Rearranged Polymers

Freeman, B. D., The University of Texas at Austin
Gleason, K. L., The University of Texas at Austin
Smith, Z. P., The University of Texas at Austin
Liu, Q., The University of Texas at Austin
Paul, D. R., The University of Texas at Austin

Results of pure and mixed-gas permeation in thermally rearranged polymers are presented.  Polyimide precursor films were converted to their polybenzoxazole (PBO) analogs to varying degrees using different thermal treatment protocols.  Structure/property relations in this family of polymers are described.  Mixed-gas permeation results are compared against pure-gas measurements.  Interestingly, CO2/CH4 mixed-gas selectivity at 35°C was 20-30% higher than the simple ratio of pure-gas permeabilities.  Strong dual-mode effects were responsible for a decrease in CH4 permeability in the presence of CO2, with very little change to CO2 permeability in the mixture.  Plasticization is not evident in the pure-gas CO2 permeation data.