Modeling Permeability In Multi-Phase Polymer Composites: A Critical Review Of Semi-Empirical Approaches

Permeation is a combination of diffusion and sorption phenomena. The extent of permeation (gas/vapor/liquid) through a composite polymer material is a function of several factors including the composition of the polymer, the nature, distribution, and spatial orientation of the different phases in the micro-structure of the matrix polymer and those of the fillers, etc. Typically, computational techniques such as Molecular Dynamics (MD) and Widom insertion are used to model the diffusion and sorption aspects of permeation respectively. However, there is a necessity to employ semi-empirical modeling to either benchmark or validate the computational results. Semi-empirical modeling, thus, offers a powerful pathway into predicting properties of composite polymers. The models themselves can be developed based on several separate but uniquely effective principles. In this review, several such categories of semi-empirical models are listed and the principles behind their development are discussed. An attempt has been made to study their corresponding effectiveness for modeling permeation in a wide range of multi-phase polymeric systems. Additionally, certain empirical models are also listed with the semi-empirical models in order to compare their respective efficacies when it comes to predicting permeant transport and related phenomena.