Compatibility of sealing materials with biodiesel, bioethanolgasoline and biodiesel-heating oil blends

摘要

Biofuels including ethanol and biodiesel (fatty acid methyl ester) represent an importantrenewable fuel alternative to petroleum-derived transport fuels.Materials compatibility is a major concern whenever the fuel composition is changedin a fuel system.The aim of this work is to study the interaction between sealing materials such asFKM (fluorocarbon rubber), EPDM (ethylene-propylene-diene rubber), CR (chloroprenerubber), CSM (chlorosulfonated polyethylene), NBR (acrylonitrile-butadienerubber), IIR (butyl rubber), VMQ (methyl-vinyl-silicone rubber) and FVMQ (methylfluoro-silicone rubber) and biofuels such as biodiesel, E85 (fuel with 85% ethanol)and B10 (heating oil with 10% biodiesel) at 70°C for 84 days. Experiments were conductedwith tests specimens of these elastomers to document the changes in themass and tensile properties of these sealing materials according to ISO 1817.The exposure tests of the elastomers in E85 showed that the weight gain caused byswelling of the test specimens was in the range of 3% to 12%. However, the weightgain of the fluorinated elastomers was at the lower end of this range. Tensile strengthand breaking elongation decreased by 22% to 61% or 13% to 77%. The lowest decreasewas determined for FKM, VMQ und IIR. These sealing materials were evaluatedas resistant to E85 up to a temperature of 70°C.Biodiesel absorbed water more quickly and aged faster than conventional diesel fuel.The weight gain of the elastomers varied between 9% (FKM) and 138% (CR) in biodiesel.FKM was evaluated as resistant with a 16% reduction in tensile strength, a2% reduction in breaking elongation and low weight loss. NBR, EPDM, CR, IIR, CSMand VMQ were evaluated as not resistant. CR even lost 100% of its original tensilestrength and breaking elongation.The highest weight gain as a result of swelling was measured for CR with 240%, IIRwith 190%, CSM with 86%, EPDM with 84% and VMQ with 54% in B10, while thefluorine-containing elastomers FKM (1%) and FVMQ (3%) absorbed much less B10and swelled less. FKM lost 23% in tensile strength and 17% in breaking elongation,and FMVQ lost 29% in tensile strength and 36% in breaking elongation. FMVQ was,therefore, only limited in its resistance to B10.The elastomers NBR, EPDM, CR, CSM, IIR and VMQ were not resistant to B10 at allas the decrease in the tensile properties was significantly over 50%. NBR lost about93% and CR and CSM about 100% of their breaking elongation.The conclusion of the investigations at 70°C is that FKM is the most resistant sealingmaterial in biodiesel, E85 (fuel with 85% ethanol) and B10 (heating oil with 10% biodiesel).