Epoxidized Natural Oils as the Alternative Safe Process Oils in Rubber Compounds

Due to a toxicity of aromatic oils derived from polycyclic aromatic hydrocarbon (PAHs), safe process oils are required for a replacement in rubber industry.  This work investigated the properties of tire tread compounds filled with high abrasion furnace black (HAF) when epoxidized palm oil (EPO) and epoxidized soya bean oil (ESBO) were used as a processing oil in comparison with a use of conventional distillate aromatic extract (DAE).  The oil characteristics were analyzed by using chemical methods, spectroscopic techniques (FTIR and NMR), differential scanning calorimetry and elemental analysis.  Influence of the oils on the properties of NR/SBR, NR and SBR compounds was investigated. All compounds with EPO and DAE oils have similar cure characteristics (i.e. scorch and cure times, torque differences) and processing properties (i.e. minimum torques and Mooney viscosities).  However, the use of ESBO clearly retards the curing reaction resulting in lower extent of crosslinking, and results in inferior mechanical properties.  The mechanical properties, e.g. hardness, modulus, tensile strength, elongation at break, tear and abrasion resistance of the compounds utilizing EPO an DAE oils are comparable, and superior to those of the ESBO added compound.  In addition, the use of EPO results in similar dynamic mechanical properties of rubber vulcanizates when compare with the use of conventional DAE.  The results indicate that the EPO is a potential candidate for a replacement of DAE oil in rubber compounds.  In addition,  by an adjustment of vulcanizing agent, the properties of the compounds with ESBO could be improved.