03/31/2026

Epoxy resins are indispensable materials in advanced composites, coatings, and structural adhesives due to their outstanding mechanical strength, chemical resistance, and thermal stability. However, the widespread reliance on bisphenol A (BPA)-based systems has raised increasing environmental and toxicological concerns. Addressing this challenge, the present work successfully demonstrates a green-by-design strategy for the development of high-performance, bio-based epoxy resins derived from renewable and environmentally benign precursors.

A central achievement of this study is the identification of aromatic bio-based building blocks capable of delivering thermomechanical properties comparable to conventional BPA-based systems. Owing to their rigid molecular architecture, these renewable precursors enable elevated glass transition temperatures while maintaining the sustainability profile of the material. To accelerate discovery and reduce experimental iteration cycles, a data-driven workflow was established. Machine learning models, trained on a curated dataset of experimentally reported epoxy systems, were employed to predict glass transition temperature directly from molecular structure. Random Forest Regression successfully identified key structural motifs governing thermal performance.

The initial model predictions revealed that epoxy systems incorporating anhydride-containing and phenolic moieties can achieve Tg values of 137 °C and 133.53 °C, respectively, when cured with anhydride-based hardeners. These findings confirm the feasibility of reaching high thermal performance without relying on BPA-derived chemistries. Although the current dataset primarily emphasizes Tg, ongoing efforts focus on dataset expansion and the implementation of Gaussian process models to enhance predictive accuracy and robustness.

Overall, this work represents a significant step toward sustainable high-performance epoxy systems. By integrating molecular design, experimental validation, and machine learning, the study establishes a powerful framework for accelerating the development of environmentally responsible thermosetting polymers with competitive industrial performance.

04/30/2025

In earlier studies by the Bio-ART consortium leader, a high-performance thermoset with 100% bio-based carbon content was produced using epoxidised linseed oil (ELSO) and citric acid (CA) [1]. However, the main limitation of such systems is generally the long curing times at high temperatures, which hinders their wider use in commercial applications. Recently, chicken eggshell powder has been investigated as a promising curing catalyst for bisphenol A diglycidyl ether epoxy resins [2]. Therefore, in Project 1.3, the effects of adding eggshell powder to an ELSO resin with a CA hardener are being comprehensively investigated and researched. The curing kinetics of the respective compositions were examined using differential scanning calorimetry, and the kinetic parameters were evaluated using several isoconversion models. Thermal analysis clearly showed that an increase in the proportion of eggshell membrane leads to a systematic reduction in the onset of curing temperature, indicating a catalytic acceleration of the cross-linking reaction. Furthermore, the data suggest that citric acid exhibits increased reactivity in the presence of the membrane, possibly due to synergistic interactions between the acidic and amine-rich environments. The results are very promising with regard to reducing curing times and temperatures for bio-based resin systems in the future and increasing energy efficiency during processing.

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[1] A. Anusic, Y. Blößl, G. Oreski, K. Resch-Fauster, Polymer Degradation and Stability 2020, 181, 109284.
[2] J. J. P. Barros, N. G. Jaques, I. D. d. S. Silva, A. K. C. de Albuquerque, A. M. Araújo, R. M. R. Wellen,Polímeros 2022, 32.