Some filler effects on diffusion in silicone rubber

摘要

AbstractThe diffusion of ethylp‐aminobenzoate in silicone rubber membranes containing varying amounts of a high surface area fumed silica filler is described, as is a new apparatus for assaying multiple samples. It is shown that increased filler loading results in what appears to be a linear decrease in transmission rate, but that apparent diffusivities fall off drastically as a result of adsorption of the permeant on the filler. Distribution coefficient measurements suffer from the same result. The results suggest that neither an unmodified time lag technique nor a direct solubility method can be used to determine diffusivities of polar or unsaturated molecules in silicone rubbers, since they generally contain silica filler