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The effect of aryl nitration on gas sorption and permeation in polysulfone

1995; Wiley; Volume: 33; Issue: 4 Linguagem: Inglês

10.1002/polb.1995.090330415

1099-0488

K. Ghosal, R. T. Chern, Benny D. Freeman, Raj Savariar,

Carbon dioxide utilization in catalysis

Abstract CO 2, CH 4, O 2, and N 2 permeability and solubility of unmodified and aryl‐nitrated polysulfone were determined at 35°C and pressures up to 20 atm. The degree of nitration was varied from 0 to 2 nitro groups per repeat unit. The permeability and diffusion coefficients for all gases decreased with increasing degree of nitro substitution. The decrease in gas diffusivity is attributed to a combination of decreased fractional free volume and decreased torsional mobility with increasing degree of substitution. The solubilities of N 2, O 2, and CH 4 do not show a systematic dependence on degree of substitution. However, CO 2 solubility apparently goes through a minimum as the degree of substitution is increased. CO 2 solubility may be influenced by a competition between increases in polymer polarity (favoring higher solubility) and lower free volume (favoring lower solubility) that accompanies increases in the polar nitro substituent concentration. CO 2 /CH 4 solubility selectivity increases monotonically as the degree of substitution increases. CO 2 /CH 4 permselectivity and diffusivity selectivity increased with increasing degree of substitution. © 1995 John Wiley & Sons, Inc.