Synthesis and characterization of rubbery/glassy blend membranes for CO2/CH4 gas separation

چکیده مقاله

Aseriesofblendmembranesmadefromthe rubbery polyether block amide (Pebax®1657) and a glassy polymer, polyethersulfone (PES) or Matrimid 5218, were fabricated by solution casting with different ratios (10–40 %), in order to combine high permeability of the former with high selectivity of the latter polymer for CO2/CH4 gas separation. The membranes were char- acterized by scanning electron microscopy (SEM), differ- ential scanning calorimeter (DSC), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), and stress–strain tests. These blend membranes showed two distinct s, indicating their immiscible nature as con- firmed by SEM images. However, weak intermolecular interaction between polymers, as illustrated by the FTIR results, corresponds to some degree to their compatibility and improved mechanical strength, compared to the pure Pebax®. TGA analysis revealed that addition of glassy polymer improved membranes’ thermal stability. Effect of feed pressure on membrane separation, investigated by three different pressures (4, 8, and 12 bar), indicated increased permeability for higher pressures for both CO2 and CH4. Gas separation tests also pointed to improved separation properties of the blend membranes compared to those of the neat polymers, prepared the same way.