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Preparation and characterization of polymeric blend and mixed matrix membranes by water vapor induced phase inversion

Kibar, Seren
Asymmetric polymeric thin film membranes are commonly produced by using non-solvent induced phase inversion process. The membrane solution is cast to a glass plate and then it is brought into contact with a coagulant. Coagulant type affects the asymmetric membrane structure and the skin formation according to phase separation mechanism. They are related with the membrane gas permeation and separation performances. In this study, asymmetric blend and mixed matrix membranes were produced by using dry/wet phase inversion method. The dry phase inversion were performed by using infrared light, while the wet phase inversion was carried out by using water vapor with 80% relative humidity as non-solvent. To achieve to desired relative humidity value, the membrane casting processes were executed in a conditioning glove box. Polyethersulfone(PES) and polyimide(PI) were used as polymeric materials for blend membrane preparation. Solvents which were used during membrane solution preparation were dimethylformamid(DMF) and tetrahydrofuran(THF). For the mixed matrix membranes, same polymers were used and the 60nm ZIF-8 was used. ZIF-8 has high gas adsorption capacity and has good chemical and thermal stability. Polymeric blend membranes were prepared with the ratio of PES/PI/20/80, PES/PI/50/50 and PES/PI/80/20. The mixed matrix membranes were produced by adding 10% ZIF-8 filler to the same polymer ratio of blend membranes. H2, CO2 and CH4 permeances of both blend and mixed matrix membranes were measured at 35°C. H2/CO2, CO2/CH4 and H2/CH4 ideal selectivities were calculated. CO2/CH4 mixture separation performances of the membranes were measured by analyzing feed and permeate gas using gas chromatography