CHARACTERIZATION OF MODEL PERFLUOROPOLYALKYLETHERS BY MINIATURIZED THERMAL OXIDATIVE TECHNIQUES .1. MODIFIED OXIDATION-CORROSION TEST

The metal catalyzed thermal oxidative stability of commercially available and model perfluoropolyalkylether (PFPAE) fluids was investigated by oxidation corrosion tests. Using model PFPAE fluids, prepared via direct fluorination of hydrocarbon analogues, a wider variety of specific molecular structures were available for study than previously available from more conventional PFPAE chemistry synthesis procedures. Because of a limited supply of the model fluids, a miniaturized oxidation corrosion test, using only 6 ml of fluid, was devised. This test, conducted at constant temperatures, was compared to a similar test using 20 ml of fluid on the more abundant commercial fluids and then extended to the model fluids. Details of the miniaturized test procedure and apparatus are presented. Also presented are the chemical structure-thermal oxidative stability relationships of the fluids as derived from this study. The destabilizing effect of an -OCF2- group is confirmed and other more subtle effects are noted.