Morphology and gas permselectivity of polymer mixture system

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In this study, to obtain the relationships between the morphologies and gas transport properties of the polymer mixture systems, the following three types of the polymer blend systems were investigated.1. polystirene/polycarbonate (PS/PC) blend systemFrom the results of DSC,WAXD,and solid-state NMR for the PS/PC blend system membranes which were prepared by solution-casting, it was confirmed that the polymer blend system is immiscible and PC component is partially crystallized. The fact that CO_2 sorption amount for the polymer blend was larger than that expected from simple additivity rule was mainly explained by the amount of the crystallite of PC.2. poly (methyl methacrylate)/poly (stirene-co-acrylonitlile) (PMMA/SAN) blend systemPMMA was found to be miscible with SAN,having an AN content from 17.9 to 39.5mol% at a level of less than 30-70*, from the ^1H spin-diffusion behavior. The CO_2 permeability and diffusion coefficients of the blend membranes were larger than those expected from the additivity rule, although the solubility coefficients follow this rule. From the dielectric relaxation spectra of PMMA/SAN blend system, it was concluded that the local mobility of PMMA was activated by blending with SAN,resulting the gas diffusion and permeability promoted some extens. Moreover, it was suggested that the distance between AN is related for the miscibility of the PMMA/SAN blend system.3. polyimide/polyimide (PI/PI) blend systemRod-like PI/flexible PI blend membranes were obtained by mixing the corresponding precursors at the various stirring temperatures. From the results of DMS and TEM,it was found that the blend systems become completely miscible when the stirring temperatures is high. The permeability coefficient of PI/PI blend membrane was higher than that expected from the additivity rule. In conclusion, the blending rod-like PI and flexible PI promotes the gas transport properties some extents.