SORPTION AND DIFFUSION OF CARBON-DIOXIDE IN SINGLE-PHASE POLYSTYRENE POLY(VINYLMETHYLETHER) BLENDS/

The sorption and transport properties of CO2 in miscible PS/PVME blend s at 20 degrees C are reported as a function of pressure from 1 to 15 atm. The complex shape of isotherms for glassy blends and the concentr ation-dependent diffusion coefficient for rubbery blends reveal a plas ticization by sorbed CO2. The significant depression in T-g has to be taken into account in the analysis of the sorption data. Diffusion coe fficient for CO2 passes through a minimum when plotted against the ble nd composition. Such a behavior can be quantitatively related to the n egative volume mixing of the PS/PVME system in the framework of the th eories based on unoccupied volume. (C) 1996 John Wiley & Sons, Inc.