Phase behavior and gas permeability of PC/PMMA blends

Abstract

Phase behavior and gas transport properties of polycarbonate, PC, blend with polymethylmethacrylate, PMMA, were investigated. Blend of PC and PMMA having relatively high molecular weight did not form miscible blend at the equilibrium state, while blend composed of PC and relatively low molecular weight PMMA formed miscible blend at the equilibrium state. Miscible blends showed LCST type phase behavior. Interaction energy density between PC and PMMA obtained from the phase boundaries and equation of state theory was 0.05 cal/cm(3). The value of interaction energy density explained well the phase behavior of blend. Even though the blends were composed of the same chemical components and com- position gas transport properties were varied with blend morphology. Gas permeability of miscible blend showed negative deviation from the additive characteristics, while that of immiscible blend showed positive deviation. The difference of gas permeation stemed from the diffusivity, i.e., difference in the free volume and morphology.