Evaluation of polyurethane/nylon 6(3) blend membranes for enhanced CO ₂ separation

In this study, the polyurethane (PU)/nylon 6(3) blend membranes were developed for gas separation applications, and influence of blending Nylon 6(3) in PU on the microstructure, and separation performance of the blend membranes was investigated. The PU was synthesized via a two‐step polymerization technique. The blend membranes were characterized by SEM, DSC, XRD, and FTIR analysis. The SEM results showed that the blend membranes containing 20 wt% or less nylon 6(3) had less interaction than those containing higher nylon 6(3) contents. At 50 wt% of nylon 6(3), the compatibility between two polymers and reducing CO 2 permeability was observed. The blending of nylon 6(3) into the PU matrix decreased the chain mobility of the membrane, increased the membrane crystallinity, and led to a rough microstructure. The neat PU and nylon 6(3) membranes had the CO 2 /N 2 selectivity of 43.1 and 14.2, respectively, while the PU60/PA40 blend membrane had the CO2/N2 selectivity of 61.9. The PU50/PA50 blend showed the highest selectivity (22.4) for CO2/CH4 separation. The CO 2 , CH 4 , and N 2 permeabilities in all membranes were enhanced by increasing upstream pressure.