Chromatographic determination of the diffusion coefficients of light hydrocarbons in polymers

Abstract

Gas-chromatographic determination of the diffusion coefficients that allows for the compressibility of the mobile phase has been suggested. The diffusion coefficients were determined for light hydrocarbons С₁–С₄ in four polymers with a high free volume, which are candidates for use as gas-separating membranes. The diffusion coefficients calculated from chromatographic data were shown to be one or two orders of magnitude smaller than the values obtained by the membrane method. This may be due to the presence of an additional flow through the membrane caused by the pressure gradient across the membrane in membrane methods.