Poly(amide-12-b-ethylene oxide)/polyethylene glycol blend membranes for carbon dioxide separation

• Pebax1074/PEG1500 blend membranes are prepared by solution casting method.
• The transport process is described in crystalline, transition and amorphous regions.
• In crystalline region, gas permeability decreases with the increase of PEG1500.
• In amorphous region, gas permeability increases with the increase of PEG1500.
• CO2 permeability is dominated by plasticization and hydrostatic pressure effects.

In this paper, block copolymer poly(amide-12-b-ethylene oxide) (Pebax1074)/poly(ethylene glycol) (PEG1500) blend membranes are prepared by solution casting and solvent evaporation method. According to DSC experiments, the melting temperature for PEO phase in Pebax1074/PEG1500 blend membranes increases with the increase of PEG1500 content, which will influence the gas transport properties. Compared with Pebax1074 membrane, the gas transport through Pebax1074/PEG1500 blend membranes can be divided into crystalline, transition and amorphous regions due to the temperature dependence of PEO thermal transition. And the gas permeability can be described by two different Arrhenius equations in crystalline and amorphous regions. For Pebax1074/PEG1500 blend membranes in crystalline region, the gas permeability is lower than that for Pebax1074 membrane, which decreases with the increasing PEG1500 content. But in amorphous region, the gas permeability is higher than that for Pebax1074 membrane, which also increases with the increasing PEG1500 content. For N2, H2 and CH4, the gas permeation behavior is mainly influenced by the hydrostatic pressure at high temperature, but for the polar gas CO2, it is dominated by CO2-induced plasticization effect and the hydrostatic pressure simultaneously.

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