Curing and Mechanical Characterization of Soy-Based Epoxy Resin System

A potentially inexpensive alternative epoxy resin system based on soybean oil has been developed for polymer composite applications. Epoxidized methyl soyate (EMS) and epoxidized allyl soyate (EAS) have been synthesized at the University of Missouri-Rolla. These materials consist of mixtures of epoxidized fatty acid esters. The epoxidized soy-based resins provide better intermolecular crosslinking and yield materials that are stronger than materials obtained with commercially available epoxidized soybean oil (ESO). The curing behavior and glass transition have been monitored with differential scanning calorimetry. Neat resin test samples have been fabricated from resin systems containing various amounts of EMS, EAS, and ESO. Standardized tests have shown that the addition of EAS enhances the tensile and flexural properties of the base epoxy resin system. Therefore, epoxidized soy ester additives hold great potential for environmentally friendly and lower cost raw materials for the fabrication of epoxy composites for structural applications.