ABSTRACT
A unique class of compounds known as polyphenyl ethers (PPEs) are mixed isomeric compounds ranging from two-ring or phenyl groups to six-ring structures that were developed for use in extreme environments, including high-temperature hydraulic, lubricant/grease, heat transfer, and other fluid applications. The PPEs are viscous, clear, light yellow liquids that possess extraordinary resistance to degradation from heat, oxygen, radiation, hydrolysis, and chemical attack. There are a number of specialty or niche applications for PPE materials. These include radiation resistant fluids and greases, connector lubricants, and vibration control lubricants. The PPEs have outstanding thermal and oxidative stability. The all-meta PPE structures have the highest thermal and oxidative stability of all other isomers of the same molecule. The surface tension of PPEs is high enough that the fluids tend not to wet metal surfaces. The PPE-based lubricants are used where extreme temperature conditions exist, such as kiln and high-temperature metal fabrication and molding.
