Experimental Study on Elastomer Compatibility with Ethanol-Gasoline Blends

Ethanol has shown tremendous potential in the journey of substitution of fossil fuels in the recent past. Primarily, the ethanol blends up to 10% in gasoline used in many countries as the existing vehicles are compatible with lower ethanol content. However, it is essential to address the compatibility of the vehicle’s fuel system when using higher ethanol-containing blends. The current study focused on the compatibility of different ethanol-gasoline blends with two widely used elastomer materials in the vehicle’s fuel system, namely, nitrile butadiene rubber/polyvinyl chloride blend (NBR/PVC) and epichlorohydrin (ECO). These materials are used for manufacturing parts like seals, gaskets, hoses/tubes, and cover of the fuel systems. The test fuels used in this study include commercial gasoline (E0), gasoline containing 10% ethanol (E10), 12% ethanol (E12), 15% ethanol (E15), and 20% ethanol (E20). The compositional analysis of NBR/PVC blend and ECO samples was undertaken using Carbon, Hydrogen, Nitrogen, Sulfur (CHNS) analyzer, Fourier-transform infrared (FTIR) spectroscopy, and Thermogravimetric Analysis (TGA). The test material specimens were immersed in test fuels at an elevated temperature of 55 ± 2°C for 1008 hr, or six weeks. Critical properties of material specimens under fresh, post immersion (wet), and dry conditions were analyzed. These properties include visual inspection, volume change, weight change, hardness change, tensile strength, and percentage (%) elongation change. Variations in properties of test specimens were used to illustrate the compatibility with test fuels. The results indicate that the volume change and weight change correspond well with hardness, tensile strength, and % elongation trends. The behavior of E10 and E12 fuels with test materials were found to be similar within a 5.0% tolerance. As we move to E15 and E20, the performance of elastomers changed moderately in certain properties, tensile strength, and % elongation change in particular.