Oxidative stability and degradation mechanism of a cyclotriphosphazene lubricant

Chromatographic and spectroscopic techniques were used to investigate the degradation products from bulk oxidative and thermal stability testing of a substituted tricyclophosphazene high-temperature lubricant. Analytical investigation into the degraded lubricant revealed oligomerization to be the dominant mode of degradation, resulting in most of the observed viscosity increases. GC/MS, FT-IR, and (31)P NMR data confirmed the existence of a cyclotetramer structure in the degraded fluid, while GPC analysis indicated the possibility of a much smaller amount of higher oligomers. The poor reproducibility observed for the oxidation results is likely due to the influence of trace contaminants or the relative degree of retention of ionizable volatile products that could act as oligomerization catalysts.