Low-Unsaturated Soybean Oils In Epdm Rubber Compounds

High oleic soybean oil and hydrogenated soybean oils having a different degree of unsaturation were investigated as bio-based plasticizers for ethylene-propylene-diene monomer (EPDM) rubber filled with carbon black and vulcanized with sulfur. The plasticizing effect of the oils with different unsaturation levels was studied by dynamic mechanical analysis (DMA) while the variation in crosslink density of EPDM rubbers was investigated by the equilibrium solvent swelling method. The linear thermal expansion coefficient (LTEC) at different temperatures for EPDM rubbers formulated with different oils was examined by thermomechanical analysis (TMA). The oil with the highest level of unsaturation demonstrates the greatest plasticizing effect but interacts with vulcanizing sulfur lowering crosslink density and deteriorating the mechanical properties of the EPDM rubber. Hydrogenated oil with all-saturated fatty acid chains shows no decrease in crosslink density, improvements in the mechanical properties of rubber but is less effective as a plasticizer for EPDM. The results of tensile testing for EPDM rubbers formulated with different concentrations of soy-based oils were studied, correlated, and discussed. The properties of soy-based EPDM rubbers compared to the properties of EPDM rubbers formulated with petroleum-based paraffinic oil.