Compatibility of Sealing Elastomers With Palm Biodiesel (B100): Elastomer and Fuel Property Changes After Exposure

ABSTRACT

The compatibility between biodiesel and elastomeric sealing materials is a key factor for the reliable operation of fuel storage and transportation systems. This study evaluates the interaction between B100 (pure) biodiesel and three elastomers used in sealing applications: ethylene‐propylene‐diene rubber (EPDM), nitrile‐butadiene rubber (NBR), and fluorocarbon rubber (FKM). Immersion tests were conducted by exposing the elastomers to biodiesel at 70°C for 70 h. Changes in biodiesel properties and the elastomers were assessed. After exposure, no significant variations were detected in the fatty acid methyl ester (FAME) composition of the biodiesel. Fuel darkening, the formation of insoluble species at low temperatures, and the increase in induction time (oxidative stability test) were observed after elastomer exposure, suggesting the migration of elastomer‐derived additives into biodiesel. EPDM showed the largest mass and volume increases, while NBR displayed intermediate behavior. FKM showed minimal changes and higher resistance to biodiesel‐induced swelling. Mechanical characterization further indicated plasticization effects in EPDM and NBR. EPDM also exhibited the greatest reductions in hardness, tensile strength, and elongation at break. Compatibility trend under the studied conditions followed the order FKM >> NBR ≥ EPDM. Complementary field evaluations under real operating conditions confirmed satisfactory performance of NBR O‐rings for 5 months.