Equation of state and high pressure properties of a fluorinated terpolymer: THV 500

Abstract

We present the results of an investigation of the static compressive and dynamic (shock) responses of a fluorinated terpolymer of tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride (Dyneon THV 500), in an effort to further understand its behavior under static and dynamic high pressures, and elucidate its equation of state properties. Fluorinated polymers, and, in particular, their copolymers, have garnered increasing attention by the static high pressure and shock wave communities, due to their widespread use in engineering applications, and formulation into energetic materials as binders. Shock wave compression experiments performed at two laboratories showed good consistency, and provide the first Hugoniot data for this fluorinated terpolymer. The Hugoniot of THV 500 is in general agreement with that of the related fluoropolymers polytetrafluoroethylene and poly(chlorotrifluoroethylene-co-vinylidene fluoride), reported previously. The static compressive data, combined with measurement of the ambient pressure thermodynamic parameters, have been used to formulate an equation of state based on the Helmholtz free energy, which was shown to adequately represent the dynamic response of the polymer to ∼5 GPa.