This report summarises the work carried out in each technical WP during the period.
WP1 (Set-up of conditions and tools to enhance material recyclability):
Work focused on sustainable strategies for epoxy resin recycling, including alternative additives, material requirements and, mainly, the search for microorganisms and enzymes with degradative potential. A successful screening and characterization of microorganisms able to survive and interact with epoxy matrices was completed. Thus, the strain Pseudomonas putida ULE23_001was confirmed as an intriguingly biological workhorse, demonstrating sustained viability on RTM6® as well as on additional resin formulations developed by ESTELLA project partners along long periods of time (> 50 days). Transcriptomic and proteomic analyses were finalised with good consistency, although no new enzymatic candidates emerged. Microbiota characterisation, partner strain collections and genome analyses produced many potential enzymes (peroxidases, lipases, esterases), some of which performed successfully in lab assays. Selected commercial enzymes were also tested individually and in combination.
WP2 (Design of thermoset polymers with CAN and natural fibre development):
Different lignin fractions were obtained, functionalised and used to formulate bio-based epoxy resins with associative CAN. Additional thermosets were produced, both fossil-based (associative CAN) and renewable-based (dissociative CAN). Various natural fibres were obtained, functionalised, characterised and applied. Reprocessability was studied for each resin type, allowing identification of the most promising one, the fossil-based resin.
WP3 (Composite preparation and properties evaluation):
Two demonstrators were designed and produced: a scooter platform and a window frame. Designs were based on the properties of matrices and reinforcements, followed by simulations. Prototype manufacturing and characterisation were completed.
WP4 (Composite recycling):
Partners studied mechanical, biological and chemical recycling routes to identify and scale up the most efficient ones. Enzymatic screenings targeted epoxy and fibre components. Enzymes able to attack key chemical bonds were produced and tested. Preliminary and scaled-up tests evaluated fibre degradation and resin recovery. Chemical recycling and self healing approaches were assessed for lignin-based resins. Fibres recovered by chemolysis proved enzymatically degradable, and combining enzymatic degradation with chemolysis showed synergistic effects. Mechanical recycling was performed on both final composites, and recycled materials were reintegrated into new matrices. Supercritical CO2 and solvolysis experiments were developed by FEY and AND.
WP5 (Safety and health assessment):
Risk assessment covered biodegradability, toxicity prediction and exposure. SINT performed chemical analyses of extractables and leachables; untargeted scans of volatiles, semi-volatiles and polar compounds are ongoing. Most tasks are in the final stages before deliverable submission.
WP6 (Social, economic and environmental assessment):
A comprehensive evaluation of economic feasibility, environmental sustainability and socio economic impacts was conducted. Market and value chain analysis established the strategic basis. TEA, SIA and LCA assessed industrial viability, costs, barriers and environmental and social impacts. Preliminary results were presented at General Assemblies, and final findings are included in deliverables D6.2 D6.3 and D6.4.
WP7 (Dissemination and exploitation):
Activities included maintaining templates, the website, social media content and biannual newsletters. The exploitation plan was finalised, with emphasis on IP management and business modelling (Canvas, SWOT).
WP8 (Project management):
Overall coordination, communication and reporting to the EC were carried out, supported by partners’ contributions and experimental results.
