Derivation and characterization of epoxidized soybean oil and epoxy resin film produced using a three step-washing neutralization process

The scientific community has recently focused on developing high-value-added epoxidized soybean oil and green bio-based epoxy resins using sustainable resources because of their cost-effectiveness and eco-friendliness. A part of this developing epoxy resin includes the replacement of conventional petroleum-based resins with their green counterparts, that is, bio-based epoxy resins. The long-term goal of this research is to develop low-cost, value-added, and bio-based epoxy resins from conventional soybean oils and commercialize the technology to be scaled up for epoxy resin production for chemical industries. Epoxidized soybean oil (ESO) was developed through the synthesis of conventional soybean oil by applying deep eutectic solvent catalysts, such as choline chloride-oxalic acid (DES-02) and choline chloride-butyric acid (DES-06) followed by three steps of washing neutralization processes. The impact of the catalysts on the epoxidation process was verified using titration methods in com-bination with infrared and nuclear magnetic resonance spectroscopies. The results showed an optimal carbon --carbon double bond conversion with a high selectivity of 73% when soybean oil was epoxidized with bifunctional DES-02 catalysts. The conventional epoxidized soybean oil synthesis without deep eutectic catalysts yielded relatively low carbon-carbon double bond conversions with 5% selectivity. Various novel bio-based epoxy resins with equal amounts of ESO and acrylic acid as monomers were developed, followed by injection molding. Bio-based epoxidized soybean resin films were characterized by dynamic mechanical and thermo-mechanical analyses. The results showed that resin films catalyzed by DES-02 and DES-06 improved the storage modulus (ca. 2000 MPa) and loss modulus (ca. 390 MPa).

Automated summary

The scientific community is focusing on developing high-value-added epoxidized soybean oil and green bio-based epoxy resins using sustainable resources. The goal is to produce low-cost, value-added, and bio-based epoxy resins from conventional soybean oils and commercialize the technology for chemical industries. The use of deep eutectic solvent catalysts in the synthesis of epoxidized soybean oil has shown improved carbon-carbon double bond conversion and selectivity. Novel bio-based epoxy resins catalyzed by these catalysts have also shown enhanced mechanical properties.