Compatibility of Biologically Derivable Alcohols, Alkanes, Esters, Ketones, and an Ether as Diesel Blendstocks with Fuel System Elastomers

The compatibility of 11 bioderivable diesel blendstocks with 17 elastomer materials common to fuel storage, dispensing, and delivery systems was evaluated though volume and hardness measurements. The blendstocks included two alcohols (1-octanol and 1-nonanol), two acid esters (methyl decanoate and hexyl hexanoate), tri­(propylene glycol) methyl ether (TPM), butylcyclohexane, two ketones (2-nonanone and 2-pentanone), biodiesel, and renewable diesel. Each blendstock was blended with diesel in concentrations of 0, 10, 20, and 30 wt %. The elastomers included two fluorocarbons, six acrylonitrile butadiene rubbers (NBRs), and one each of fluorosilicone, neoprene, polyurethane, styrene butadiene rubber (SBR), hydrogenated acrylonitrile butadiene rubber (HNBR), a blend of NBR and PVC (OZO), epichlorohydrin/ethylene oxide (ECO), ethylene propylene diene monomer (EPDM), and silicone. Specimens of each elastomer material were immersed in the test fuels for a period of 4 weeks and measured for volume and hardness. Afterward, they were dried at 60 °C for 20 h and remeasured. The results showed that the alkanes, esters, and alcohols were suitable with many of the elastomers. For some materials, such as neoprene, these blendstocks improved the compatibility compared to neat diesel. In contrast, the ketones and TPM produced unsuitable volume expansion (>30%) and softening in many of the elastomers including the high-performance fluoroelastomers. Analysis of the results showed that the swelling behavior is predominantly due to polarity of the elastomer and test fuels.