Polymer components servicing in motor vehicle fuel systems are exposed to elevated temperatures and fuel contact, which may lead to performance loss and severe vehicle operational problems, such as fuel leakage and fuel pump failures. In recent years, the degradation of polymers in vehicle fuel systems have gained increasing attention due to the increase in engine temperatures and use of renewable biofuels such as bioethanol and biodiesel. In this study, the deterioration of polyamide 12 (PA12), one of the most common polymers used in vehicle fuel system, was studied after ageing in petroleum diesel, biodiesel and their mixture (with 20 vol.% of biodiesel) in autoclave at 125 °C. The degradation mechanisms involved the fuel uptake by, and extraction of monomers/oligomers from PA12. The kinetics of fuel uptake and its influence on the glass transition temperature were accessed. The results showed that Youngs’ modulus decreased by 40 % during first 48 h exposure due to the plasticizing effect of fuels, and then increased slightly upon further ageing because of an increase of crystallinity caused by the annealing effects. The samples also underwent extensive oxidation after prolonged ageing, leading to the embrittlement, as revealed by the decrease in strain-at-break.<br/>

Degradation of polyamide 12 exposed to petroleum diesel, biodiesel and their mixture

256th National Meeting (2018)

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