Phosphonitrilic Fluoroelastomers—A New Class of Solvent Resistant Polymers with Exceptional Flexibility at Low Temperature

Abstract

Abstract Many commercial elastomers exhibit good solvent resistance and high temperature stability but have limited use at low temperature. Fluorosilicone, which exhibits good low temperature properties, is limited in many dynamic applications by its poor physical strength. Phosphonitrilic fluoroelastomers are being developed for applications which require solvent resistance, low temperature flexibility, and good physical strength over a broad range of service conditions. A brief description of the synthesis and characterization of these new polymers has been presented in the forms of chemical, chromatographical, spectroscopical, physical testing, and rheological studies. The main object of this paper has been to provide an introduction to the art of processing, vulcanization, and reinforcement of these elastomers to produce useful commercial items. These fluoroelastomers can be processed on conventional equipment for dry-mixing rubber. Vulcanization can be effected with either organic peroxides or sulfur-accelerator cure systems. These vulcanizates can be reinforced with silicas, carbon blacks, or silane-treated clays to give stocks with a wide range of modulus, strength, hardness, and service temperatures (−80 to 400° F) in many service fluids and atmospheres. The exceptional solvent resistance, low temperature flexibility, and wide temperature service range indicate that phosphonitrilic fluoroelastomers should find use in items such as O-rings, Arctic fuel hose, lip seals, gaskets, and vibration damping services.