Mechanisms of gas permeation through polymer membranes. Progress report, July 1, 1985-May 31, 1986. [CH/sub 4/, C/sub 2/H/sub 6/, n-C/sub 4/H/sub 10/, CO/sub 2/ in poly(n-butyl methacrylate)]

Technical Report · Thu May 01 04:00:00 EDT 1986

OSTI ID:5571129

Stern, S A; Vakil, U; Zhou, S

The work described is concerned with the significant changes in these mechanisms in the glass-transition range. Permeability, diffusion, and solubility coefficients for CH/sub 4/, C/sub 2/H/sub 4/, C/sub 2/H/sub 6/, and n-C/sub 4/H/sub 10/ in poly(n-butyl methacrylate) (PnBMA) were determined at pressures up to 25 atm and from -14/sup 0/ to 50/sup 0/C. Solubility was also determined for CO/sub 2/ in PnBMA at pressures up to 25 atm and at -10/sup 0/ and 30/sup 0/C. No significant changes were observed in the pressure (or concentration) and temperature dependence of the permeability, diffusion, and solubility coefficients for CH/sub 4/, C/sub 2/H/sub 6/, and n-C/sub 4/H/sub 10/ in the glass-transition range of PnBMA, or when the temperature was lowered below T/sub g/. Moreover, these gas/polymer systems do not exhibit below T/sub g/ the usual ''dual-mode'' sorption behavior of gases in glassy polymers. The solubility isotherm for CO/sub 2/ in PnBMA at -10/sup 0/C and lower pressures suggests incipient dual-mode sorption. Results are exceptions to dual-mode sorption behavior and may be due to small difference in the coefficients of thermal expansion of PnBMA above and below T/sub g/. This indicates that the unrelaxed domains in glassy PnBMA are very small. A ''free-volume'' mechanism describes the dependence of C/sub 2/H/sub 6/ permeability on P, T both above and below the glass transition of PnBMA. Adsorption/desorption kinetics are Fickian.

• Research Organization: Syracuse Univ., NY (USA). Dept. of Chemical Engineering and Materials Science
• DOE Contract Number: AC02-78ER05015
• OSTI ID: 5571129
• Report Number(s): DOE/ER/05015-T3; ON: DE86013368
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360404* -- Materials-- Polymers & Plastics-- Physical Properties-- (-1987)
ADSORPTION
ALKANES
BUTANE
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
DESORPTION
DIFFUSION
DIMENSIONS
ETHANE
HYDROCARBONS
MEMBRANES
METHANE
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PERMEABILITY
PHYSICAL PROPERTIES
POLYMERS
RESEARCH PROGRAMS
SOLUBILITY
SOLVENT PROPERTIES
SORPTION
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
THICKNESS
TRANSITION TEMPERATURE