Diffusion Mass Transfer in Composite Membranes
Particulate-filled polymer composite membranes are two-phase heterogeneous membranes consisting of filler particles dispersed uniformly or randomly in a polymer matrix . The incorporation of filler particles to the polymer matrix can reduce or enhance the permeation of species through the membrane depending upon the permeability of the species in the filler particles. In some practical applications, it is desirable to reduce the permeability of a species through the membrane (barrier membranes) whereas in other applications, it is important to increase the permeability of a species (mixed matrix membranes). Barrier membranes with reduced permeability are widely used in the packaging industry [2,3]. They are also used as anticorrosive coatings [4-6]. Mixed matrix membranes (MMMs), on the other hand, are designed to have high permeability and high permselectivity for a species of interest. They are composed of porous “molecular sieve type” inorganic fillers and polymeric matrix and are very effective in the separation of gaseous mixtures [7-19]. Particulate-filled polymer composite membranes are finding applications in polymer electrolyte membrane (PEM) fuel cells as well . In the PEM fuel cells, the proton permeability and the mechanical strength of polymer electrolyte membrane could be improved significantly by filling the polymer matrix with inorganic particles of high proton permeability.