Swelling of Nitrile Rubber by Selected Aromatics Blended in a Synthetic Jet Fuel

Abstract

To examine the contributions of different types of aromatics, the volume swell of nitrile rubber O-rings was determined in aromatic-free synthetic JP-5 fuel and in synthetic JP-5 fuel blended with selected aromatics. Additionally, partition coefficients between the O-ring and fuel phases were measured for the fuel and aromatic species. Volume swell was measured using an in situ optical dilatometry technique that provided temporal data, while partition coefficients were measured using direct thermal desorption GC-MS analysis of swollen O-ring samples. For the hydrocarbons studied, the data indicate a correlation between partition coefficient and volume swell. The propensity to swell nitrile rubber was found to increase with the polarity and hydrogenbonding character of the aromatics, suggesting that swelling of nitrile rubber requires disrupting the attractive forces between cyano groups on adjacent polymer chains and replacing them with cyano group-aromatic interactions. Volume swell was also found to decrease with increasing molecular weight.

A review of the combustion and emissions properties of advanced transportation biofuels and their impact on existing and future engines

“…Fischer-Tropsch synthesis results in hydrocarbon molecules with no oxygen content, leading to excellent compatibility with existing engine and fueling infrastructure [37,94]. The lack of aromatic content in Fischer-Tropsch fuels can lead to issues associated with poor lubricity and seal-swell problems that must be overcome for it to be used within the current ground and air transportation fleets [36,[94][95][96]. Aromatic compounds, such as benzene or toluene, are hydrocarbon molecules that are stabilized by shared electrons within their carbon-ring structure, and are named as such due to their characteristic sweet smell.…”

Dependence of Fuel Properties During Blending of Iso-Paraffinic Kerosene and Petroleum-Derived Jet Fuel

“…Research is being conducted to determine the minimum aromatic levels required to swell o-rings. 15,18 If additional research shows that a lower minimum percentage of aromatic content can adequately provide seal swell and other FFP characteristics, then the linear functional dependence will be used to maximize the percentage of FT while maintaining levels required for the proper function of fuel system materials. …”

“…Several studies have been performed to characterize the use of upgraded FT-derived fuels for aviation applications. [1][2][8][9][10][11][12][13][14][15][16][17][18][19] Studies with neat FT fuels have demonstrated that significant improvements in thermal oxidative stability and emission production can be realized while superior low-temperature properties can be achieved with a sufficiently high iso-alkane/n-alkane ratio. However, the IPK will not meet the JP-8 specification density requirement (minimum 0.775 g/mL) or potentially other specification and -Fit-for-Purpose‖ (FFP) properties.…”

Fatigue of swollen elastomers

“…Polymer oxidation can be initiated when stabilizer additives are extracted during exposure to solvents, especially for B100. Indeed, the immersion of rubbers in solvents risks the extraction of fillers or additives (Richaud et al, 2013;Seehra et al, 2012;Graham et al, 2006;Trakarnpruk and Porntangjitlikit, 2008). The oxidation process eventually induces chain scission and decreases the polymer resistance to failure (Richaud et al, 2013).…”