Fully Bio-Based Epoxy Thermoset Based on Epoxidized Linseed Oil and Tannic Acid

Increasing demand for bio-based epoxy thermoset alternatives has risen in the last few years. Epoxidized vegetable oils (EVO) have attracted significant attention due to their bio-based, unharmful nature and high availability. This study proposes a fully bio-based epoxy thermoset based on epoxidized linseed oil (ELO) and tannic acid (TA). TA allows, with its high degree of functionality and aromatic structure as a curing agent for ELO, to create a fully bio-based polymer network with a high glass transition temperature (T_g), high stiffness, and high strength. A maximum T_g of 146 °C, a flexural modulus of 2986 MPa, and flexural strength of 72 MPa are obtained. The strong material properties of the TA/ELO thermoset expose its potential as a bio-based substitute for petrochemical-based epoxy resins for high-performance applications.