Description of non-ideal effects in composite membranes by a new theoretical approach

Abstract

In present study, a theoretical model is introduced to calculate the gas permeability of mixed matrix membranes (MMMs) containing porous fillers. This model is based on analogy of gas permeation in MMMs with tensile modulus in composites. The representative parameters of MMM morphologies such as polymer chains tightening around the filler (β<1), unselective channel formation (β>1) and polymer chains penetrating into filler pores (0≤α≤1) which leads to the filler pore blocking are all included in the model. Furthermore, the interphase thickness (t) which is a critical parameter of MMMs participates in calculation equation along with the other parameters. To validate the proposed model, an experimental study with poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) blend as polymer matrix and zeolite 4A and NH2-MOF-199 as fillers is performed. The obtained gas permeability data of constructed MMMs and some of the literature data are employed to be fitted with the proposed model. The details of the existence morphologies of MMMs can be described by earning the mentioned parameters ranges. Therefore, by this model, by having a measure of t, the gas permeation of MMM can be achieved accompany with details of the related morphologies. All the theoretical investigations are done utilizing one equation which contains all parameters simultaneously.