A novel nano structured blend membrane for gas separation

This investigation involves the preparation and characterization of poly (urethane)/poly (vinyl acetate) (PU/PVAc) blend membranes. PU was synthesized by two step polymerization from toluene diisocyanate (TDI), poly (propylene glycol) (PPG) and 1, 4-butanediol (BDO).Fourier transform infrared (FTIR) spectroscopy was used to verify the chemical structure of the resulting polymer. Blend membranes with a thickness of 100 μ were prepared from the solution of PU and PVAc in chloroform by a solution-evaporation method. The amount of PVAc was varied among 10, 20 and 30 percent by weight of the membrane. Scanning Electron Microscopy (SEM) was used to investigate the morphology of the prepared membranes. The membrane containing 20% by weight of PVAc displayed a more homogenous dispersion of PVAc domains and was selected for gas permeation tests. For this purpose; oxygen (O₂), nitrogen (N₂), carbon dioxide (CO₂) and methane (CH₄) gases were used and the gas pressure was varied between 2, 4, 6, 8 and 10 bars. Comparison of the results with that of the pure PU membrane revealed that the blend membrane had a higher permeability to CO₂ and a lower permeability to the other gases and therefore had a higher value of CO₂/N₂ and CO₂/CH₄ ideal selectivity.