Calculation of solubility parameters from inverse gas chromatography

One frequent industrial use of the solubility parameter concept is in the prediction of compatibility in polymer-plasticizer systems. As dictated by their conditions of use, the compounds used as plasticizers are usually large, involatile organic molecules such as the alkyl phthalates so that the above comments are also applicable to their δ₂ values. Thus, it was of interest to determine the applicability of the IGC method to these compounds. Experimental data indicate that for the less polar compounds, the best agreement with literature values is observed with the results from the alkane probes but this does not hold for the polar NMP (N-Methyl Pyrrolidone) and DEBH (Dibutyl-2-Ethyl Hexamide). Were polar forces becoming increasingly important at higher δ₁ values, the graphs would be expected to show an increase in slope and this is indeed found for the polar components.