Prediction of long-term physical aging of poly(methyl methacrylate) membranes for gas separation

Short- and long-term physical aging tests of high molecular weight poly(methyl methacrylate) (PMMA) membranes have been performed at different temperature. The effects of physical aging on the gas permeation properties are studied. Experimental data show that the physical aging decreases the volume of free volume hole and permeability but increase selectivity. Acceleration of physical aging can be realized by applying high temperatures, and a master curve can be constructed using the time-temperature superposition concept. A modified three parameter fit model is obtained and predicts the long-term physical aging behavior with good agreement with experiments.