Inverse gas chromatographic study of the oxidation stability of lubricating base oils via solubility parameter calculations.

The Flory-Huggins interaction parameter (chi1, 2(infinity)) and solubility parameter (delta2) and its hydrogen bonding sensing component (delta(h)) were determined using inverse gas chromatography (IGC). These parameters were successfully used in the probes of chemical changes that occur during the oxidation of naphthenic and paraffinic base oils in a GC column. Changes in chi1, 2(infinity) values reflect the different types of intermolecular interactions (dispersive, polar, hydrogen bonding) of the given lubricating base oil during oxidation. The obtained results showed that delta(h) component of solubility parameter is the most important parameter for probing the oxidative-chemical changes during the oxidation of given lubricating oils.