Elastomer—Gasoline Blends Interactions II. Effects of Ethanol/Gasoline and Methyl-t-Butyl Ether/Gasoline Mixtures on Elastomers

Abstract

Abstract The effects of ethanol/gasoline and MTBE/gasoline mixtures on swell and tensile properties of selected automotive elastomers were determined and compared to those of methanol/gasoline mixtures. Two gasolines with aromatic content of 30% and 50% were used in this investigation. Equilibrium swell and tensile measurements were conducted using ASTM standard procedures. Results show that in the case of ethanol/gasoline combinations, the elastomers were more severely affected by the mixtures than by the pure components. The ethanol/gasoline mixtures are less severe than the methanol/gasoline mixtures in their effects on most fuel resistant elastomers. In the case of MTBE, effects of mixtures with gasoline were an average of the effects of the pure components. The presence of a higher aromatic content in the gasoline resulted in increased swell and, hence, increased deterioration of tensile properties of elastomers exposed to the gasoline and its mixtures. Addition of benzene to increase the aromatic content resulted in slightly more detrimental effects on nitrile elastomers than the addition of toluene. The data on all elastomers can be explained in terms of the solubility parameter concept. For most elastomers, the ultimate tensile and elongation values were found to be quantitatively related by simple linear equations to the volume fraction of the rubber swelled in mixtures of gasoline and ethanol or MTBE. They were also found to be related to each other by simple logarithmic relationships.