Thermal decomposition of fluoropolymers: Stability, decomposition products, and possible PFAS release

The thermal degradation of fluoropolymers poses potential environmental and regulatory challenges due to their emissions of fluorinated byproducts. This study investigates the thermal stability and degradation products of polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), and polyvinylidene fluoride (PVDF) across temperatures ranging from 200 to 890 °C. Different from previous studies, no short- or long-chain per- and polyfluoroalkyl substances (PFAS) were detected under any tested condition. Among the investigated polymers, PTFE have shown highest stability, remaining intact until ≥ 550 °C and then mainly depolymerizing to tetrafluoroethylene (C₂F₄). In contrast, PCTFE and PVDF degrade at lower temperatures (400-500 °C), generating halogenated byproducts such as chlorotrifluoroethene (C₂ClF₃), chloropentafluoro-1-propene (C₃ClF₅), fluorobenzenes (C₆H₃F₃, C₆H₄F₂), and dichlorohexafluorobutene (C₄Cl₂F₆) that was detected for the first time. This study reports the first-time yields of fluorine (F) release varied across the different fluoropolymers, with PTFE exhibiting the highest F yield, releasing up to 0.8 g fluorine/g PTFE at 600 °C, whereas PCTFE and PVDF peaked at ∼0.4 and 0.5 g/g, respectively, near 500 °C.