Fluoropolymers are used in corrosive and other challenging environments due to their unique chemistry. The stability imparted by the fluorine bond prevents degradation by harsh chemical environments, and also provides other benefits such as resistance to fire, ultraviolet radiation and thermooxidative degradation. While polymers without fluorine chemistry may use additives to prolong decomposition in these harsh conditions, these additives are used up over time. The initial cost of fluoropolymers may be higher due to both material costs and additional processing considerations necessary to make articles; however, the longevity of the articles will exceed that of hydrogenated polymers and metals in various harsh environments.
Poly(vinylidene fluoride) PVDF
PVDF is a partially fluorinated polymer with the best mechanical properties of all fluoropolymers, with a modulus of up to 2100 MPa. The chemical resistance to acids is excellent and can be in contact with bases to pH 12. The continuous use temperature of PVDF not under mechanical stress is 150°C (302°F).
Poly(ethylene-co-chloro, tricloro ethylene) ECTFE Halar
ECTFE is a partially fluorinated polymer that is more resistant to bases than PVDF. It can be used down to pH 14 with many chemicals. ECTFE is also more permeation resistant than PVDF for most chemical enironments. The modulus of ECTFE is lower than PVDF (Up to 1650 MPa), and is more expensive than PVDF. The continuous use temperature of PVDF not under mechanical stress is 150°C (302°F).
Poly(perfluoroalkoxy alkane-co-tetrafluoroethylene) PFA
PFA is a fully fluorinated polymer that is more resistant to polymer degradation than partially fluorinated polymers. Chemical resistance is influenced by temperature, and some chemical environments suitable for partially fluorinated polymers at ambient temperatures would only be suitable for fully fluorinated polymers at elevated temperatures. The upper use temperature of PFA not under mechanical stress is between 225 and 260°C (437 to 500°F), depending on the grade used. The resistance to permeability and mechanical properties such as modulus (up to 600 MPa) and creep resistance of PFA, are inferior to partially fluorinated polymers.