For sustainability reasons recently, synthetic aviation turbine fuels have become increasingly important as blending components for conventional fuels in both civil and military aviation. In order to ensure that existing aircraft can be operated with these new energy sources without further modifications, it must be examined, among other things, what influence synthetic fuels have on installed elastomeric sealing materials with regard to swelling in comparison to conventional fuels. This work deals with this question. For this purpose, fundamental diffusion mechanisms of fuel-typical model substances are investigated in elastomers, especially in acrylonitrile-butadien-rubber (NBR). A time resolved analysis of the mass transport of the individual substances as well as their mixtures is carried out in the polymeric materials using sorption experiments, which are assisted by gas chromatography/mass spectrometry (GC/MS). Furthermore, the influence of different parameters such as temperature or composition of the elastomers as well as mixtures of model substances on the occurring mass transport phenomena are investigated. Results show that the diffusion behavior of mixtures is dominantly influenced by components with the higher individual swelling potentials. Especially aromatic hydrocarbons increase the diffusion rate and are accumulated in the elastomers. Based on the obtained findings, compatibility tests between elastomers and different (modified) synthetic and conventional aviation turbine fuels are carried out, whereby storage tests are performed at different temperatures. The stored samples are chemically and mechanically examined at different times, whereby fuel uptake, additive concentrations and parameters such as density, hardness and tensile strength are determined. It is found that synthetic and conventional aviation fuels, which exhibit same concentrations of aromatics, show a nearly identical influence on the chemical and mechanical properties of the elastomers. To provide a fast method for the prediction of the swelling degree of an elastomer in contact with a certain fuel, chemometric models based on UV/Vis, infrared and mass spectra are developed. The calibration is performed with model substance mixtures, as these provide more flexible models compared to real fuels. Validation results show that models based on infrared spectra exhibit the highest prediction qualities, while models, which are based on UV/Vis spectra can only be used for rough estimations.    «

For sustainability reasons recently, synthetic aviation turbine fuels have become increasingly important as blending components for conventional fuels in both civil and military aviation. In order to ensure that existing aircraft can be operated with these new energy sources without further modifications, it must be examined, among other things, what influence synthetic fuels have on installed elastomeric sealing materials with regard to swelling in comparison to conventional fuels. This work de...    »