Polymer formation during thermal-oxidative ageing of aviation turbine oils

Abstract

Oligomers/polymers formed during the thermal-oxidative ageing of ester-based aviation turbine oils have been investigated, using pentaerythritol tetraheptanoate as a model ester. The principal polymer structures in the primary ageing state were revealed by means of chromatographic and spectroscopic methods. The most probable structures are dicarboxylic acid polyesters with variable amounts of α,ω-dicarboxylic acids having chain lengths of C2 up to C7 The C7-branches also contained ester-bonded hydroxy as well as oxo substituents. Pentaerythritol triheptanoate discarboxylic acid mono esters were active precursors in polymer formation.