Structure–property relationships of model chlorstrifluoroethylene oligomer compounds: Thermal stability

Abstract

Low molecular weight chlorotrifluoroethylene (CTFE) oligomers have been the base fluid for an extensive DoD research and development programme for nonflammable hydraulic fluids, compatible elastomeric seals, components, and systems. To gain a more fundamental understanding of the effect of the specific isomers and other components of commercial CTFE fluids on the important fluid properties, model compounds were synthesised and their physical and chemical properties were determined. Thermal stability, in the presence of typical hardware system metals, is one of the more important properties and is discussed in relation to molecular structure. Two Microscale evaluation techniques were devised and validated. Optimum thermal stability is observed when the chlorines in the molecules are positioned as far apart as possible. In general, it was found that the compounds with larger amounts of chlorine were less stable and the positioning of the chlorine in the molecule had a lesser, but measurable effect.