The Permeation Effect of Ethanol-containing Fuels on Fluoropolymers

The barrier properties of fluoropolymers exposed to ethanol-containing fuel blends were investigated using the permeation cup, weight loss method. More specifically, permeation constant data for Fuel C, CE10, CE15, CE22, CE50, CE85 and ethanol through fluoropolymers; THV, PVDF and FEP were measured at 20, 40 and 60°C. Additional techniques such as the measurement of vapor pressure of fuel-ethanol blends using a permeation cup equipped with a pressure transducer are discussed. Vapor pressures for fuel blends were also derived using equations of state such as UNIQUAC, NRTL and Peng-Robinson models. The weight changes and volume changes of fluoropolymers in ethanol-containing fuels were measured. Finally, the crystallinity index and glass transition temperature of fluoropolymers were also measured.