Infinite dilution diffusion coefficients of n-hexane, n-heptane and n-octane in polyisobutylene by inverse gas chromatographic measurements

Abstract

Based on the Hadj-Romdhane–Danner model of the chromatographic process, the infinite dilution diffusion coefficients of n-hexane, n-heptane, n-octane and toluene in polyisobutylene (PIB) have been measured at temperatures in the range of 323.2–373.2 K by inverse gas chromatography (IGC). The measured infinite dilution diffusion coefficients for the toluene/PIB system were compared with the diffusivity data at finite concentration determined previously from NMR experimental method by using the Vrentas–Duda free volume theory. The good agreements indicate the IGC method studied in this work is reliable. Moreover, the correlations of the experimental data with the free volume equation were preformed. The correlated results show that the free volume theory is a quite good description of the relationship between the observed solvent diffusion coefficient and temperature.