Polymer/fuel interaction and properties of typical automotive fuel-system polymers exposed to methanol blended (M15) gasoline

Methanol blended with gasoline (M15) is a potential alternative transportation fuel option. It can provide benefits like reduced emissions from tail-pipe of vehicles and savings of import duty on crude oil. Three elastomers including Fluroelastomer (FKM), Epichlorohydrin (ECO) and Polyvinylchloride/Nitrile butadiene rubber (PVC/NBR) and a plastic Polyamide (PA-66), which are widely used in fuel-system components were tested for their compatibility with methanol blended (M15) gasoline and Gasoline (E0, as a baseline reference fuel) as per the guidelines given in SAE J1748. Identification of materials, fuels (before and after immersion) were done by FT-IR analysis. Impact of fuels on material properties was evaluated on the basis of appearance, volume/swell, weight change, tensile strength, % elongation, impact strength (for plastics) and hardness (for elastomers). Assessment of properties of materials was carried out after ageing of elastomers and plastic in fuels for 1008 Hrs (similar to 6 weeks) and 3024 h (similar to 18 weeks), respectively. We have reported relative change of properties, after immersion in M15 with respect to gasoline. This is carried out by taking ratio of absolute value of a property after immersion in M15 to the absolute value of same property after immersion in gasoline (E0). Therefore, any change greater than one represents higher change (multiples of the change in E0) in M15 than that in gasoline. Epichlorohydrin showed the highest change in all the properties amongst the three elastomers in M15 as compared to gasoline (E0) except for the weight change. A significant change in volume was observed in case of ECO followed by FKM and PVC/NBR post aging/immersion. Whereas, PVC/NBR showed minimal change in all properties compared to FKM and ECO. PA 66 showed substantial increase in weight and decrease in tensile strength after immersion in M15 compared to gasoline. The information generated in this study on compatibility of polymers with M15 will help fuel system component manufacturers, vehicle designers, materials engineers in selecting, manufacturing appropriate/alternate materials which can provide service for its intended application. This will enable and policy makers to take informed decisions on implementation of policies related to utilization of M15 as an alternate fuel in future.

Automated summary

Testing the compatibility of three elastomers and one plastic material widely used in fuel-system components with methanol blended gasoline (M15) and gasoline (E0) is crucial for potential benefits like reduced emissions and savings on import duty. Results showed significant changes in material properties in M15, with Epichlorohydrin exhibiting the highest changes and PVC/NBR showing minimal changes compared to the baseline fuel.