Measurement of diffusion coefficients of non-polar alkane solvents at infinite dilution in polyethylene membrane

Gas chromatography is a new, fast, accurate and convenient technique for studying the relationship between small molecule solvents and polymer membrane materials. Many parameters of dissolution and diffusing characters of a small molecule in a polymer can be measured by this method. The retention time and the peak width at half-height of three small molecule solvents (n-heptane, n-nonane and n-decane) in the stationary phase of polyethylene were measured. The diffusion coefficients of the small molecule solvents at infinite dilution were calculated with van Deemter equations. The graphs plotted according to the results of the diffusion coefficients of the three solvents at infinite dilution vs. temperature were in agreement with the Arrhenius equation. The variance in the diffusion coefficients at infinite dilution of the three small molecule solvents was analyzed according to the differences in molecular mass.