Temperature dependence of gas sorption and permeation in PIM-1

In a prior paper gas sorption, permeation and diffusion coefficients were determined for He, H₂, N₂, O₂, CH₄, CO₂, C₂H₄, C₂H₆, C₃H₆ and C₃H₈ in PIM-1, a polymer of intrinsic microporosity, at 25°C over a range of pressures. Here similar measurements and analyses were made at temperatures from 25 to 55°C over a wide range of pressure. In all cases, the sorption isotherms were generally consistent with the form of the dual-sorption model. For He, H₂, N₂, O₂, CH₄ and CO₂, the effects of plasticization were minimal and the results could be effectively analyzed by the dual sorption-dual mobility model, and the temperature dependence of the model parameters were analyzed to obtain the energetic parameters for the sorption and diffusion processes. However, for C₂H₄, C₂H₆, C₃H₆ and C₃H₈, plasticization was quite significant and temperature dependent; as a result, a similar analysis in terms of the dual sorption-dual mobility model could not be meaningfully carried out. For all gases, a more phenomenological analysis of P, D and S was made in terms of simple Arrhenius and van't Hoff relations to obtain energetic parameters that subsequently depend on pressure because of some combination of dual mode and/or plasticization effects.