(148b) Simulation of Polymer Barriers with Various Inorganic Particulates to Achieve Ultra-Low Permeance of Small Molecules

The development of submicron membrane for filtration requires understanding of the movements of fluids both in the bulk regime and the molecular regime.  Much of this same understanding is needed in creating barriers to small molecule diffusion.   To this end, models to describe the effect of incorporating impermeable fillers on the transmission rate of small molecules through polymer barriers were developed.  Two different types of particulates, spheres and platelets, of various sizes, arrangement and loading were investigated.  Three dimensional simulation of diffusion through the structures were studied to provide deeper insights into the impact of these fillers. These simulation models looked at both the bulk diffusion and the Knudsen diffusion to capture the behavior for a large range of filler loads and for a large range of permeance for the base polymer.

Depending on the loadings of the filling and the concentrations of the diffusing molecule, the dominant mechanism for diffusion can vary between a bulk diffusion regime and a Knudsen diffusion regime. The various equations developed from the correlation in this work can be applied in both of these regimes. This allows for a better understanding of the impact of these fillers, especially, for the requirement of high barrier properties where both regimes could be important. The simulation approach used in this work can be employed to greatly reduce the amount of experimentation which is needed to develop novel barrier technologies and provide a methodology for future work in this area.