Eutectic hardener from food-based chemicals to obtain fully bio-based and durable thermosets

Tellers, Jonathan; Willems, Philippe; Tjeerdsma, Bôke F.; Guigo, Nathanaël; Sbirrazzuoli, Nicolas

doi:10.1039/d0gc00311e

Cited by 18 publications

(34 citation statements)

References 47 publications

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“…As hardener, the recently developed eutectic hardener was employed based on a 1:1 molar mixture of CA and EL (CAEL-Hardener), which stays liquid at room temperature. [34] After the previous investigations, [34] the ratio of epoxy and acid groups was fixed at R = 0.8 (epoxy/acid).…”

Section: Thermoset Preparationmentioning

confidence: 99%

“…Moreover, in such application, curing at room temperature should be considered as appliers usually spread the resin on the countertop and they have no possibilities to heat. The actual thermoset system studied here is comprised of epoxidized linseed oil (ELO) as matrix and our recently published eutectic biobased hardener consisting of a mixture of citric acid (CA) and ethyl lactate (EL), [34,35] to induce a cross-linked network. In contrast to previous work, this paper will investigate in detail the curing behavior, reaction kinetics, and mechanical properties of the final materials with and without added SCGs.…”

Section: Introductionmentioning

confidence: 99%

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Spent Coffee Grounds as Property Enhancing Filler in a Wholly Bio‐Based Epoxy Resin

Tellers

Willems²,

Tjeerdsma³

et al. 2021

Macro Materials & Eng

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Coffee is one of the most popular beverages in the world but generates copious amounts of waste that is usually discarded. This discarded waste, the so-called spent coffee grounds (SCGs), can become a valuable resource if compelling use cases are found. Following a circular economy approach, one such use case can be employing SCGs as filler in polymer matrices, complementing conventional inorganic fillers such as kaolin clay. This work studies the effect of SCGs as filler in wholly natural thermosets, investigating changes in curing kinetics and final material properties. Different SCG content, for example, 25 to 35 wt% and various curing time and temperature is employed. SCGs are found to have a moderate catalytic effect on the curing reaction. Furthermore, SCGs are found to heavily increase stiffness of the final material, especially when oils present in SCGs are previously extracted, raising the rubber plateau modulus from around 5 MPa to 14 MPa. Extracted SCGs are most efficient during curing at room temperature, where they significantly improved the tensile strength, toughness, and hardness of the filled material compared to the pristine resin.

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Section: Thermoset Preparationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Spent Coffee Grounds as Property Enhancing Filler in a Wholly Bio‐Based Epoxy Resin

Tellers

Willems²,

Tjeerdsma³

et al. 2021

Macro Materials & Eng

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“…14−16 The main drawback of these hardeners is their toxicity, and hence, the solution is to turn to carboxylic acids. In the literature, ELO has been cross-linked with citric acid 17 or with long-chain dicarboxylic acids. 18−20 A new synthesis route is to react ELO with a hardener present in vegetal biomass like suberin.…”

Section: ■ Introductionmentioning

confidence: 99%

Suberin from Cork as a Tough Cross-Linker in Bioepoxy Resins

Menager

Guigo

Vincent

et al. 2021

ACS Appl. Polym. Mater.

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The cross-linking between epoxidized linseed oil (ELO) and suberin has been investigated. Suberin is the major component of cork which can be extracted by hydrolysis. In this study, ELO was cross-linked with suberin with the aim to make fully biobased and nontoxic thermosets without addition of catalysts and to valorize cork coproducts. Polymerization mechanisms were investigated by Fourier transform infrared, rheology, and advanced isoconversional kinetic analysis. Finally, thermomechanical properties have been studied by thermogravimetric analysis, dynamic mechanical analysis, and tensile tests. These experiments highlight that cross-linked ELO/suberin films have a wide relaxation temperature range and a tunable glass transition temperature (T g ) between 57 and 66 °C depending of the suberin ratio in the reaction medium.

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“…Thus, DES has also gained attention for the development of thermosetting resins. [29][30][31][32] For instance, DES consisting of choline chloride and ZnCl 2 or SnCl 2 can be simultaneously employed as an efficient curing agent for epoxy resin and anti-flaming agent. 30 Besides, a eutectic mixture between ethyl lactate and citric acid has been reported for curing the epoxidized linseed oil at room temperature, with the curing system exhibiting natural, abundant, inexpensive, non-toxic and even food contact approved constitents.…”

Section: Introductionmentioning

confidence: 99%

“…30 Besides, a eutectic mixture between ethyl lactate and citric acid has been reported for curing the epoxidized linseed oil at room temperature, with the curing system exhibiting natural, abundant, inexpensive, non-toxic and even food contact approved constitents. 32 Considering the fact such DES systems generally contain ZnCl 2 or urea, these can be suggested to be suitable for curing phthalonitrile. However, to the best of our knowledge, no relevant study employing these systems has been reported so far.…”

Section: Introductionmentioning

confidence: 99%

Deep eutectic solvent for curing of phthalonitrile resin: Lower the curing temperature but improve the properties of thermosetting

Weng

Song

et al. 2020

High Performance Polymers

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Long curing duration and high curing temperature are commonly known to restrict the application of the phthalonitrile resin. In this study, a deep eutectic solvent (DES) containing ZnCl2 and urea has been developed to improve the curing process of the resorcinol-based phthalonitrile resin (DPPh) without sacrificing the useful properties of the resin. For the molar ratio of ZnCl2 and urea as 1:1 (ZnCl2-urea (1–1)), the initial curing temperature and apparent activation energy of the system were recorded as 179.5°C and 90.1 kJ/mol, respectively, indicating a reduction of 31.2% and 39.0% as compared to the pristine ZnCl2 system. More importantly, with curing time of 6 h and post-curing temperature of 300°C, the temperature at 5% weight loss as well as glass transition temperature of the resin with DES as the curing agent were 523.1°C and 370.2°C, respectively, demonstrating a significant improvement as compared to the resin cured with ZnCl2. In addition, the satisfactory long-term oxidation stability of the resin could also be obtained by employing the new curing agent. The findings from this study open a functional pathway for facile preparation of the high-performance curing agent for the phthalonitrile resin.

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Eutectic hardener from food-based chemicals to obtain fully bio-based and durable thermosets

Abstract: This paper presents a facile strategy to activate citric acid (CA) for room temperature curing.

Cited by 18 publications

References 47 publications

Spent Coffee Grounds as Property Enhancing Filler in a Wholly Bio‐Based Epoxy Resin

Spent Coffee Grounds as Property Enhancing Filler in a Wholly Bio‐Based Epoxy Resin

Suberin from Cork as a Tough Cross-Linker in Bioepoxy Resins

Deep eutectic solvent for curing of phthalonitrile resin: Lower the curing temperature but improve the properties of thermosetting

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