Decomposition of fluoroelastomer: Poly(vinylidene fluoride-ter-hexafluoropropylene-ter-tetrafluoroethylene) terpolymer in subcritical water. (September 2017)

• Record Type: Journal Article
• Authors: Hori, Hisao; Tanaka, Hirotaka; Tsuge, Takahiro; Honma, Ryo; Banerjee, Sanjib; Ameduri, Bruno
• Is Part Of: European polymer journal. Volume 94(2017)
• Page Start: 322
• Page End: 331
• Publication Date: 2017-09
• Subjects: Decomposition -- Elastomer -- Fluoropolymer -- Mineralization -- Recovery -- Supercritical water; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; Polymerization; Polymers; Periodicals; Electronic journals; 547.705
• DOI: 10.1016/j.eurpolymj.2017.05.042
• Languages: English
• ISSNs: 0014-3057

Abstract

Graphical abstract: Highlights: Poly(VDF- ter -HFP -ter -TFE) terpolymer showed little reactivity in pure subcritical water under argon. Addition of H2 O2 efficiently accelerated the decomposition of poly(VDF- ter -HFP -ter -TFE) terpolymer to F − . The maximum yields of F − and CO2 reached both 95%: quasi-complete mineralization was achieved. Reaction in the presence of 4.0 M H2 O2 and stoichiometric Ca(OH)2 at 350 °C resulted in the formation of CaF2 in 84% yield. Abstract: Decomposition of poly(vinylidene fluoride- ter -hexafluoropropylene- ter -tetrafluoroethylene) terpolymer, a typical fluoroelastomer with high flexibility and high resistance to permeation of oil and excellent adhesive ability to other materials, in subcritical water (SubCW) was studied as a first example of the decomposition of the terpolymer with the aim of developing a technique to recover the fluorine element. Compared to the common fluoropolymers such as poly(vinylidene fluoride), the terpolymer was considerably stable in SubCW. 19 F NMR spectral analysis of the decomposition products obtained from the reaction at 300 °C was carried out to better understand the decomposition mechanism. When the reaction was performed in SubCW at 300 °C for 6 h under argon, only a negligible amount of F − ions (1%) was released. Addition of H2 O2 into the reaction system accelerated the mineralization of the terpolymer to form F − and CO2 . Apart from these major products, small amounts of malonic acid and CF3 H were detected. When this polymer was heated in SubCW at 350 °C with 4.0 M H2 O2, both the yields of F − and CO2 reached up to 95%. These features indicate a quasi-complete mineralization of the terpolymer. Furthermore, the reaction in the presence of 4.0 M H2 O2 and stoichiometric amount of Ca(OH)2 at 350 °C for 18 h resulted in the formation of pure CaF2, a raw material for hydrofluoric acid, in 84% yield.