Synthesis of a Sustainable and Bisphenol A‐Free Epoxy Resin Based on Sorbic Acid and Characterization of the Cured Thermoset

Abstract

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.

Kinetic Modeling of the Synthesis Path for the Production of a Sustainable Epoxy Resin Based on Allyl Sorbate

“…The commercial standard epoxy component DGEBA yields 9.4%. The difference in OOC results from the higher density of epoxy groups per mass in EGCHC than in DGEBA which leads to a lower epoxy equivalent weight in the sustainable epoxy . Though, in the present study, only theoretical observations are made to interpret the model results and expand the model predictions.…”

“…The difference in OOC results from the higher density of epoxy groups per mass in EGCHC than in DGEBA which leads to a lower epoxy equivalent weight in the sustainable epoxy. 11 Though, in the present study, only theoretical observations are made to interpret the model results and expand the model predictions. Figure 12 shows the relative progress in oxirane oxygen formation η for the different tested reaction temperatures within 1 day.…”

“…Detailed information on the analysis method and synthesis procedure can be found in the Supplementary Information and our previous publication. 11 Total sample volumes were kept <5% of the reaction volume. Thus, all reactions are modeled in batch with the assumption of constant volume over reaction time.…”

“…IPD is available with a bio-based carbon content of up to 90%, 17 further increasing the total bio-based carbon content of the cured resin to 75%, exceeding competitors 10 while maintaining the required thermo-mechanical properties. 11 As the proposed novel molecule shows promising properties, details on the reaction should pave the way for further elaboration on the production. Thus, reaction models of the crucial reaction steps are postulated.…”

“…Previously, we reported a novel synthesis route to an epoxy compound which can readily be produced with a bio-based content of >68% and also is completely BPA-free . Additionally, the chemicals used in the current synthesis strategy can reportedly be produced with renewable resources − or alternatives are at hand. , Furthermore, synthesized 1,2-epoxy-6-methyl-triglycidyl-3,4,5-cyclohexantricarboxylate (EGCHC) cured with isophorone diamine (IPD) shows promising mechanical properties with high glass transition temperatures up to 131 °C and a tensile stress of up to 50 MPa.…”