What is Epoxidized Soybean Oil?

Epoxidized soybean oil (ESBO) is a semi-solid, pale yellow liquid produced by oxidizing the double bonds present in unsaturated fatty acids that make up soybean oil. This process, called epoxidation, involves reacting soybean oil with peroxide in the presence of an acid or base catalyst. The resulting product, ESBO, contains epoxy groups in its chemical structure that provide unique properties and make it well-suited for use in a variety of industrial applications.

Chemical and Physical Properties 
From a chemical standpoint, epoxidized soybean oil is comprised largely of epoxidized derivatives of the three main fatty acids found in soybean oil - linoleic acid, linolenic acid, and oleic acid. The epoxidation process introduces epoxy groups (-O-) into the carbon chains of these unsaturated fatty acids. This modification imparts ESBO with an oxirane oxygen content of around 7-9%.

ESBO is a pale yellow liquid at room temperature with a faint characteristic odor. It has a density between 0.96-1.01 g/cm3 and a viscosity ranging from 1,500-10,000 cP depending on oxirane content and processing method. ESBO has good thermal stability with a flash point over 495°F and is non-toxic. Its epoxy groups make Epoxidized Soybean Oil highly reactive and water-absorbent, allowing for further chemical reactions and uses.

Uses of Epoxidized Soybean Oil
As an epoxy plasticizer: ESBO is widely used as a plasticizer for polyvinyl chloride (PVC) and other polymers due to its ability to plasticize and improve flexibility and oil resistance in finished products. This application area accounts for over 50% of global ESBO usage.

As a reactive diluent: The epoxy groups in ESBO allow it to function as a reactive diluent in epoxy resin systems, helping to reduce viscosity during mixing and application while still participating in the final cure reaction. This expands the range of epoxy resin applications.

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