Palm and soybean biodiesel compatibility with fuel system elastomers

• Device developed evaluate effects of diffusion and stress on elastomer degradation.
• Due to composition and unsaturated molecules, biodiesel causes material degradation.
• Based on little changes in tensile strength and hardness, FKM is more compatible with biodiesel.
• Soybean biodiesel causes more changes in swelling and mechanical properties for NBR.

The present study aims to investigate the impact of biodiesel on the degradation behavior and sealing ability of elastomers such as nitrile rubber (NBR) and fluorocarbon (FKM). Pressurized tests were carried out with biodiesel of palm and soybean oil and a system piston-cylinder of steel SAE 1045. The fluid pressure applied was 200 bar and the time test was 5 h. The results showed a decrease in mass of the NBR for all biodiesels. Upon exposure into biodiesel, both tensile strength and hardness were reduced but in different proportions for biodiesels tested. FKM exhibited good resistance to degradation and keeping its swelling ability. The surface of elastomers was a little modified showing pits and cracks.