Application of inverse gas chromatography to the examination of annealing processes of semi-synthetic base oils

The Flory–Huggins χ∞1,2 parameter and solubility parameter δ2 determined by means of inverse gas chromatography (IGC) were successfully used in the physicochemical characterisation of oxidation products of mineral oil–poly-α-olefin mixtures. Application of IGC parameters allows one to examine the changes occurring during three different oxidation procedures: classical oxidation in a stainless steel reactor, in a GC column and separate oxidation of the mixture’s components. Changes in χ∞1,2 values reflect the changing affinity of mixtures to different types (dispersive, polar, hydrogen bonding) of intermolecular interactions and their potential miscibility and solubility.