Predictions of barrier properties of filled polymer layers, 2010 TAPPI Advanced Coating Fundamentals Symposium

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Barrier coatings and films are important in a number of products. Particles in these barrier layers are known to decrease the transport rate through the film, but a good quantification of this phenomenon is lacking in the literature. The diffusion equation is solved in two and three dimensions for films that contain spherical particles using a finite element package. The total flux rate is predicted for different concentration of spheres, packing geometries, and for spheres of two sizes. The net flux rate through the structures is found to be not only a function of the diffusion path length, but the cross sectional area available for diffusion. The two dimensional results could not be simply scaled to predict the three dimensional results. A simple expression is proposed that predicts the results for all the three dimensional cases independent of the packing geometry and the mixtures of sphere sizes.