The Role of Interfacial Morphology in the Gas Transport Behavior of Nanocomposite Membranes: A Mathematical Modeling Approach

The presence of polymer particle interactions in composite materials leads to the formation of interfacial layers with physical properties significantly different from those of the polymer matrix and fillers. Mathematical modeling of the interfacial morphology in mixed matrix membranes (MMMs) not only considerably depends on the assumed interface thickness, but also is related to the applied modeling algorithm. In the current study, a new algorithm is developed to estimate the interface thickness based on findings of molecular dynamics and Monte Carlo simulations in the literature as well as the size and the loading of the particles. Moreover, effective permeability of the MMMs is predicted with no need to evaluate the permeability of the particles and the type of interfacial morphology by only adjusting the reduced permeability factor in the range of -0.5 to 1. On the basis of the proposed modeling approach, characteristic parameters of encapsulated particles by interfacial layer, beta and gamma, can be simply determined from the corresponding contour line of gamma and beta for the description of permeability through it. Initially, the effective permeability of composites comprising encapsulated particles by the interfacial layer is assessed by adjusting only one parameter after determining effective interface thickness. The comparison between the predictions and the reported experimental permeability data of 17 series of the MMMs confirmed that the accuracy of the modified Maxwell model based on the proposed modeling approach is more than 95% for more than 90% of the predictions, while the maximum average absolute relative error (AARE) is 8.3%.