The effect of humidity on the CO2/N2 separation performance of copolymers based on hard polyimide segments and soft polyether chains: Experimental and modeling

Finally, we modeled the humidity-induced decrease of gas solubility, diffusivity and, consequently, permeability, using a suitable approach that considers the free volume theory for diffusion and LF model for solubility. Such model allows estimating the extent of competition that the gases undergo with water during sorption in the membranes, as a function of the relative humidity, as well as the expected reduction of free volume by means of water molecules occupation and consequent reduction of diffusivity.