Fuel and Permeation Resistance of Fluoroelastomers to Methanol Blends

Ethanol and methanol are oxygen containing, pollution control additives that can be used in automotive gasoline.  Ethanol is typically used in the United States, with gasoline blends up to 85% ethanol available.  In China, where methanol is made from coal and plentiful, methanol is the preferred additive for fuel blends.  While blends up to 15% methanol are common in China, levels much higher are used in some regions.  Concurrently there is a drive by automotive companies to develop engines for use in global platforms.  Global specifications for fuel systems that can operate in flex fuels including fuel blends containing up to 85% methanol are being developed.  While the effect of fuel/ethanol blends on fluoroelastomers has been well documented, there is limited information on the resistance of fluoroelastomers to fuel methanol blends especially at elevated temperatures.

Experiments have been conducted to document the change in volume swell, tensile properties, and permeation rates of fluoroelastomers typically used in fuel systems.  The fluoroelastomers were exposed to blends of fuel C and methanol with the physical property testing completed after immersion at 60°C and the permeation testing at 40°C.