Characterization and Gas Permeation Properties of Synthesized Polyurethane-Polydimethylsiloxane/Polyamide 12-b-Polytetramethylene Glycol Blend Membranes

Blend membranes of synthesized polyurethane (PU) based on toluene diisocyanate (TDI), polydimethylsiloxane (PDMS) and polytetramethylene glycol (PTMG) with polyamide 12-b-polytetramethylene glycol (PA12-b-PTMG) were prepared by a solution casting technique. The heterogeneous microstructures of the blend membranes (PU/PA12-b-PTMG) were characterized by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Gas transport properties were determined for O-2, N-2, CH4, and CO2 gases and the obtained permeabilities were correlated with polymer properties and morphology of the membranes. Comparison of the results with that of the pure PU membrane indicates that the blend membranes had higher permeability to CO2, but lower permeability to O-2, N-2 and CH4 gases, and, therefore, had higher values of CO2/N-2 and CO2/CH4 ideal gas pair selectivities. The blend membrane with 20 % (wt) PA12-b-PTMG showed the highest CO2 permeability (approximate to 105 Barrer) compared to the PU and other blend membranes. In the blend membranes with 5-20 % (wt) PA12-b-PTMG contents an enhancement of CO2/CH4 (approximate to 10) and CO2/N-2 (approximate to 52) selectivities was observed. The experimental permeabilities of the blend membranes were compared with the calculated permeabilities based on a modified additive logarithmic model.