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. IntroductionEpoxy thermosets (EP) are well established in a large variety of applications, including electronic encapsulation, paints, coatings, adhesives, sealants, and composite materials. EPs represent a prominent place in the thermosetting market. Its market is expected to witness further growth in the forecast period of 2021-2026, growing at a Compound Annual Growth rate (CAGR) of 5%, and is projected to reach ≈4.3 million metric tons by 2026. [1] About 90% of the epoxy thermoset is derived from diglycidyl ether of bisphenol A (DGEBA). The raw materials for DGEBA, bisphenol A (BPA), and epichlorohydrin (ECH) are petroleum-based and cause adverse effects on living organisms and ecosystems. Glycerol, a byproduct from the biodiesel industry, can be used to produce ECH. However, considerable

In the present study, an epoxy compound, 1,2‐epoxy‐6‐methyl‐triglycidyl‐3,4,5‐cyclohexanetricarboxylate (EGCHC) synthesized from sorbic acid, maleic anhydride, and allyl alcohol is proposed. Using commodity chemicals, a bio‐based carbon content of 68.4 % for the EGCHC resin is achieved. When cured with amine hardeners, the high oxirane content of EGCHC forms stiff cross‐linked networks with strong mechanical and thermal properties. The characterization of the epoxy specimens showed that EGCHC can compete with conventional epoxy resins such as DGEBA. A maximum stiffness of 3965 MPa, tensile strength of 76 MPa, and Tg of 130 °C can be obtained by curing EGCHC with isophorone diamine (IPD). The cured resin showed to be decomposable under mild conditions due to the ester bonds. The solid material properties of EGCHC expose its potential as a promising bisphenol A, and epichlorohydrine free alternative to conventional petroleum‐based epoxies with an overall high bio‐based carbon content.

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