Effect of sub‐ T g annealing on CO 2 sorption in polycarbonate

High pressure CO 2 sorption data in polycarbonate (PC) are reported as a function of temperature and thermal history. The bulk physical structural changes produced by annealing at 125 and 135°C were monitored by density and thermal property changes. The sorption data are analyzed by the dual sorption model which assumes the sorption isotherm to consist of Henry's law and Langmuir sorption terms; The Langmuir capacity term C of PC can be grossly correlated with the reported volumetric parameters of the polymer. This excess volume interpretation of C has found support in the good correlation between C and the corresponding enthalpy relaxation from parallel Differential Thermal Analysis of the samples. Density measurements provide gross evidence of the free volume interpretation of C . The experimental uncertainties in the data compromise a more critical test of the relationship between C and the density of annealed samples.