V. N. Bakunin

Nanosized structures in high-temperature oxidation of lubricating oil hydrocarbons

Peculiarities of high-temperature (150–170°C) oxidation of hexadecane as a model mineral lubricant are considered. Kinetic features of the oxidation process are presented, indicating a nonisothermal reaction mode, which can be caused by accumulation and decomposition of associated polyhydro-peroxides in the oxidizing system. The association of polyhydro-peroxides leads to formation of structures like reversed micelles, and evidence for their formation was obtained by the dye solubilization technique. The formation a microheterophase system at early stages of oxidation leads to reaction inhibition due to the formation of micellar aggregates in hydrocarbon oxidizing systems.

Influence of the structure of higher paraffin hydrocarbons and their derivatives on the mechanism of high-temperature liquid-phase oxidation

The specifics of oxidation kinetics at 160°C for structurally different hydrocarbons (normal and isobranched chains) and some of their functional derivatives were studied. A comparative analysis of products of the high-temperature oxidation of hydrocarbons was made and changes in the phase composition were studied using squalane and hexadecane as examples. It was shown that the spatial structure of a hydrocarbon subjected to oxidation makes a substantial contribution to the formation of reversed micelles. The kinetic behavior of squalane in oxidation and the solubilization of methyl orange by its oxidation products support the assumption that polyhydroperoxides form via the intramolecular 1,3-hydrogen abstraction mechanism.

Action mechanism of oil‐soluble potassium‐containing antioxidant synergists: evidence for micellar inhibition

One of the most promising synergistic compositions for use in high‐temperature lubricants comprises aromatic amine and an oil‐soluble alkali metal compound although action mechanism of this synergism is still questionable. The greatest efficiency of this additive pair is demonstrated for PEE based compositions using thin‐layer oxidation test at 250°C. Addition of potassium‐containing additive to aromatic amine antioxidant results in decreasing of formation of strongly‐oxidized substances. Determination of electrophysical parameters (dielectric constant and specific conductivity) for tested samples indicates formation of reversed micelles at the potassium content of about 0.6⋅10‐2 mol/l, and the latter corresponds to the potassium content that provides the highest antioxidant efficiency. A novel method of inhibiting oxidation is proposed: micellar inhibition that suggests novel possibilities for protection of lubricants against oxidative degradation.