High glass transitions, high storage moduli, high thermal stability, and low water absorption values are crucial criteria of high-performant materials, though there is a challenge when we are confronting the bio-resourced materials with their performances. This work proposes the chemical combination of aromatic bio-based epoxy monomers with potential bio-based anhydrides to produce thermosetting materials with competitive performances. Triglycidyl ether of phloroglucinol (TGPh) and diglycidyl ether of vanillyl alcohol (DGEVA) were copolymerized with hexahydro-4-methylphthalic anhydride or methyl nadic anhydride. These copolymerization reactions start at low temperature, from 35 or 70 °C; that is a first advantage for an industrial up-scaling. The produced thermosets have high bio-based carbon content, ∼50–60%, high glass transition values (>100 °C for DGEVA-based resins and >200 °C for TGPh resins), high storage moduli (2.7–3.1 GPa at 30 °C), high thermal stability (T 5% = 329–359 °C), and very low water absorption (in average ∼1.5% after 15 days). These performances of these bio-based thermosets open windows of application in space, aerospace, or naval industry.

A scheme of development of rigid and elastic materials with a biobased carbon content >54% from humins biorefinery by-products.

The need for thermosets from renewable resources is continuously increasing to find eco-friendly alternatives to petroleum-derived materials. Products obtained from biomass have shown to play an important role in this challenge. Here, we present the structural characterization of new biobased thermosets made of humins, a byproduct of lignocellulosic biorefinery, and glycidylated phloroglucinol coming from the biomass phenolic fraction. By employing attenuated total reflection-Fourier transform infrared and NMR spectroscopies, we elucidated the connections between these two systems, contributing to clarify their molecular structures and their reactivities. We demonstrated that the resin curing takes place through ether bond formation between humin hydroxyl functions and phloroglucinol epoxides. Besides cross-linking, humins show a complex rearrangement of their furanic structure through different concomitant chemical pathways depending on the reaction conditions.

Biobased resins and composites with high biobased carbon content were prepared and characterized. Epoxidized linseed oil (ELO) was copolymerized with four cyclic anhydrides, the initiation step being optimized in terms of initiator nature and its ratio. The optimized ELO/anhydride formulations were combined with a high load of lignin, as biofiller, ~30 wt%. The obtained materials were characterized by TGA, DSC, DMA, gel content, water absorption (WA) and Shore hardness tests. The results revealed very good thermomechanical properties, high gel content and low WA, opening the way to their utilization as a sustainable alternative to oil-based resins and composites.

The combination of eco-respectful epoxy compounds with the humins, a by-product of biomass chemical conversion technologies, allow the obtention of materials with high added value. In this work, we propose a chemical connection study of humins with two aliphatic bis-epoxides through copolymerization reactions to synthesize sustainable, bio-based thermosets. The mechanism insights for the crosslinking between the epoxides and humins was proposed considering the different functionalities of the humins structure. Fourier Transform InfraRed (FT-IR), one dimensional (1D) and two-dimensional (2D) Nuclear Magnetic Resonance (NMR) spectroscopy techniques were used to build the proposed mechanism. By these techniques, the principal chain connections and the reactivity of all the components were highlighted in the synthesized networks.

There is an imperative need to find sustainable ways to produce bisphenol A free, high performance thermosets for specific applications such as the space or aerospace areas. In this study, an aromatic tris epoxide, the tris(4-hydroxyphenyl)methane triglycidyl ether (THPMTGE), was selected to generate high crosslinked networks by its copolymerization with anhydrides. Indeed, the prepared thermosets show a gel content (GC) ~99.9% and glass transition values ranged between 167–196 °C. The thermo-mechanical properties examined by DMA analyses reveal the development of very hard materials with E′ ~3–3.5 GPa. The thermosets’ rigidity was confirmed by Young’s moduli values which ranged between 1.25–1.31 GPa, an elongation at break of about 4–5%, and a tensile stress of ~35–45 MPa. The TGA analyses highlight a very good thermal stability, superior to 340 °C. The Limit Oxygen Index (LOI) parameter was also evaluated, showing the development of new materials with good flame retardancy properties.

Keratin, a valuable protein obtained from chicken feather waste from the food industry, was used in this study in combination with a biobased formulation of epoxidized linseed oil (ELO) and dodecenylsuccinic anhydride (DDSA). The influence of keratin on the ELO cross-linking reaction was studied using differential scanning calorimetry (DSC) and in situ Fourier transform infrared (FT-IR) spectroscopy, showing the chemical contribution of the protein during network formation. Moreover, keratin showed a positive effect on the overall performances of the network, glass transition, storage modulus, and tensile strength, proving its potential in developing sustainable materials with industrial application potential.

The environmental pollution is growing continuously -causing a worldwide problem. Production and use of petroleum-based materials but also huge quantities of industrial wastes are important factors that affect the wellbeing of the environment. New scientific researches place great emphasis on waste valorization, and also on developing new environmentally friendly bio-based materials. In this work we focus on the valorization of humins, a biorefinery side product, by its copolymerization with a bio-based triepoxide. In this manner we produce materials with a very high bio-based carbon content (BCC) ≈ 94%. The physico-chemical and mechanical properties of the cured bio-based resins were investigated using different technics as TGA, DMA, Shore hardness test, water absorption and solvents resistance. It was revealed that the obtained materials present very good mechanical properties with values of E' in glassy region ≈ 3.7-5 GPa. The tan δ -maxima of the three huminsbased resins are ranging from 122 to 154 °C. The thermosets' hardness values ≈ 82-85 SD confirm the stiffness of these materials.