Depolymerizable bio-based multifunctional closed loop recyclable epoxy systems for energy efficient structures

Project Information

REPOXYBLE

Grant agreement ID: 101091891

DOI

10.3030/101091891

EC signature date 29 November 2022

Start date 1 December 2022

End date 30 November 2026

Funded under

• Digital, Industry and Space

Total cost

€ 3 810 103,00

EU contribution

€ 3 810 103,00

Coordinated by

AVANZARE INNOVACION TECNOLOGICA SL
Spain

Periodic Reporting for period 2 - REPOXYBLE (Depolymerizable bio-based multifunctional closed loop recyclable epoxysystems for energy efficient structures)

Reporting period: 2024-06-01 to 2025-05-31

Summary of the context and overall objectives of the project

Lightweight materials such as glass and carbon fibre composites are commonly used due to their intrinsic properties. However, the poor recyclability and recovery aspect poses a significant challenge. This issue becomes even greater when using thermoset matrices. The end-of-life aspect of these materials is crucial, as when landfilled they release toxic substances into the environment. Minimising resource use, energy of manufacturing processes and optimising waste disposal of future advanced materials can help mitigate cost and product’s end-to-end footprint across its global lifecycle, thereby significantly improving its overall environmental performance. These are critical problems that OEMs (vehicle manufacturers) in the transport sector are currently facing.
Cost-saving through the reduction of overall weight is a primary driver towards the adoption of advanced lightweight materials in the transport sector: the lighter the weight, the lesser the fuel consumption and environmental footprint.
In recent years, for example, there has been a transition from petrol cars to electric cars to minimise the carbon footprint. However, there is a challenge of reducing the overall weight of the batteries. If lightweight materials are used, they can compensate for the heavy battery weight, extend vehicle range and cost benefits.
Optimising performance while maintaining environmental sustainability, especially end-of-life (EoL) management of lightweight composites, is a significant drive and a huge challenge.
To bring new advanced transportation concepts to life, future materials must be more lightweight, recyclable, multifunctional and cost-effective than ever before. Moreover, integrating multiple functions into materials can help reduce lead times during manufacturing and enable predictive maintenance. Further multi-functionality will enable
advanced concepts and improve performance of transportation systems.
The need of a new class of high performance materials—bio-composites—is emerging to offer even more exciting possibilities for improved environmental performance as engineers aim to unlock their potential for use in future transportation systems.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The partners have developed several actions, with main outcomes, listed below:

1. Selection of the cleavable hardeners has been performed, achieving its synthesis and purification with yields improved to approximately 70%. Solvent use was significantly reduced by nearly 35%, and solvent recovery processes were implemented. Safety evaluation (human and environmental hazards) of the benchmark materials and the developed Repoxyble components, shows that cleavable hardener seems to have lower toxicity profile than the commercial benchmark. The experiments with the functional additives showed a lower toxicity profile.
2. Optimisation process of the curing and proving the fitting of the digital model for optimal curing with experimental data obtained by DSC.
3. Thermal stabilities of above 300ºC and Tg between 100 and 120ºC could be obtained for the epoxy resin systems containing cleavable hardener.
4. Good compatibility of the fibers with the epoxy resin systems has been confirmed.
5. Optimization of the parameters and conditions of the depolymerization process of the selected epoxy resin systems.
6. Graphene foils prepared and introduced in coupons of composites, aiming dissipate heat in a more efficient way. Creation of embedded circuits by laser printing.
7. Upscale and validation of depolymerizable epoxy systems at kg scale. 2 kg of prepreg was successfully manufactured.
8. For the aerospace domain, two structural demonstrators were fully designed: a wing flat panel and a curved engine nacelle panel for the HYPLANE hypersonic spaceplane. These panels were defined in terms of geometry, laminate architecture, and mechanical loading conditions.
9. Two automotive demonstrators were selected and developed — a rear intake manifold and a structural roof component — with emphasis on integrating fast-curing, bio-based resin formulations and transferring aerospace manufacturing knowledge to the automotive sector.
10. Development and preliminary validation of graphene-based strain sensors for structural health monitoring, fabricated using graphene oxide inks and tested under uniaxial strain conditions, demonstrating consistent and anisotropic electrical response both parallel and perpendicular to the loading axis.
11. Surrogate models based on IR curing data were developed using genetic algorithms, enabling identification of energy-minimizing curing parameters across varied layups and geometries.
12. Sustainability verification work by expanding the life cycle assessment framework with upscaled data, including use-phase and end-of-life models based on actual component production.

In summary, during this 30 months; the components of the new composites have been obtained and scaled up, achieving good quality impregnation of the fibers and a new methodolghy to prepare composite by using IR Out-of-Autoclave procedure. It has been demostrated a reduction in the energy consuption needed for the preparation of the panels.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Some of the results obtained during this first reporting period are beyond the state of the art and working at lab scale.
For example:
- the scaled up and validatation of a depolymerizable epoxy based resin. The technology has to be protected (the partners are working for patent protection) and the access to market, explotaition has to be done. Inside the consortium it can be a supplier of the raw materials after its validation.

- Integrated circuits and antennas in the composites will be validated and tested in real enviroments. The technologies have to be protected and commercialized.

- IR fast curing protocols for composites using additives to speed up the curing time; this technology has to be validated and protected.

materials and procedures