CO2 solubility and diffusivity in poly(vinyl acetate) studied using the PC-SAFT and free volume theory

Poly (vinyl acetate) (PVAc) is a polymer used in various industrial applications, and the quantitative determi-nation of CO2 solubility and diffusion coefficient is important for designing foaming processes involving su-percritical CO2. In this study, these two physical properties were obtained experimentally and theoretically using the perturbed chain-statistical associating fluid theory (PC-SAFT) and free volume theory at temperatures be-tween 353 K and 473 K and pressures up to 20 MPa. CO2 solubility increased almost linearly with pressure and could be correlated with the PC-SAFT equation of state and binary interaction parameter kij within the average relative deviation of 2.1%. Furthermore, the fitted plot of kij versus temperature can be used to predict CO2 solubility at lower temperatures. The diffusion coefficient of CO2 in PVAc was experimentally determined from CO2 sorption curves. Its value increased with increasing CO2 solubility and temperature, which was consistent with the free volume theory.