Epoxidized Soybean Oil (ESO) is a chemically modified derivative of soybean oil, produced through the epoxidation of its unsaturated fatty acids. This process introduces epoxy groups into the triglyceride structure, enhancing its thermal and oxidative stability. ESO is widely used as a bio-based plasticizer and stabilizer in polymer formulations, particularly in the production of flexible PVC. It improves flexibility, UV resistance, and heat stability while offering a safer alternative to traditional phthalate-based plasticizers. Although derived from a natural source, ESO is classified as a UVCB substance due to its complex and variable composition. Its applications span across the plastics, coatings, adhesives, and sealants industries, where it contributes to performance, sustainability, and regulatory compliance in modern material design.