INVESTIGATION OF INFLUENCE OF ESTER STRUCTURE ON THERMAL-OXIDATIVE OILS STABILITY

Abstract

This work aims are analysis the influence of the structure of esters on their thermo-oxidative stability. Then we select the composition of additives to improve the oxidation properties of aviation turbine engines. As the main method we used the following study: Standard Test Method for Corrosiveness and Oxidation and Stability of hydraulic oils, aircraft turbine engine lubricants and other highly refined oils ASTM 4636-99. It has been found that the esters of dicarboxylic acids and aliphatic alcohols have a low thermal oxidative stability, which may result in frequent change in the oil lubrication system and washing with gasoline or jet fuel. Thus, compositions based on esters of dibasic acids and aliphatic alcohol are good plasticizers having abrasion resistance and frost resistance. Thought they have low pour points and high viscosity index. As a basis for aviation oil hindered esters are recommended, which have high thermal oxidative stability. In the industry esters obtained by etherification of the mixture of acids and a polyhydric alcohol are used. Esters are optimal on its viscosity-temperature properties which were obtained in the reaction of etherification of pentaerythrit and trimetilolpran alcohols, and mixtures of hexane, heptane, nonanoic, octanoic acids. Physico-chemical parameters of esters are improved with increasing in number of functional groups in the molecule. The reason for this is that the esters were obtained by the reaction of etherification of n-C9 acids with pentaerythritol alcohols which forms a sterically hindered ester. This structure has no hydrogen atom in the molecule in β-position, which prevents the formation of cyclic hydrocarbons. However, to get oils with high performance require it is necessary to add additives. Therefore, domestic and foreign literatures and requirements for oxidation stability were analyzed. Based on these data the main requirements were formulated for oil composition of aircraft gas turbine engines. As the results of the oxidative stability testing it were found that to obtain oil which satisfies to all modern requirements for thermal oxidative stability, it requires the use of complex of antioxidants of phenolic and amine types. Forcitation:Tonkonogov B.P., Bagdasarov L.N., Popova K.A., Agabekov S.S. Investigation of influence of ester structure on thermal-oxidative oils stability. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 2. P. 73-79