The Decomposition Reaction Path of a Linear PFPAE Under Tribological Conditions
It has previously been shown using F nuclear magnetic resonance (NMR) spectroscopy that a linear perfluoropolyalkyl ether (PFPAE) fluid undergoes decomposition by a disproportionation reaction mechanism to form acid fluorides when heated in the presence of aluminum chloride. It is shown in this study that the same linear PFPAE fluid decomposes by the same reaction mechanism to form the same acid fluorides when heated at 345°C in the presence of dry air and bearing steels. Then, it is shown that these acid fluorides readily undergo hydrolysis to carboxylic acids when they are exposed to atmospheric moisture. Finally, carboxylic acids were detected in highly stressed linear PFPAE fluids exposed to the atmosphere after recovery from fatigue testing experiments. Therefore, it is concluded that under real tribological conditions, linear PFPAE fluids initially decompose in the presence of bearing steels by a disproportionation reaction mechanism to form acid fluorides which subsequently react with atmospheric moisture to form carboxylic acids.
perfluoropolyalkyl ether, polyether, PFPAE, decomposition, NMR spectroscopy, FTIR spectroscopy, acid fluorides, hydrolysis, lubricant
Helmick, L. S. (1998). The Decomposition Reaction Path of a Linear PFPAE Under Tribological Conditions. Tribology Letters, 4, 287-292.