Evaluation of the recyclability of the developed matrices

Grant Agreement number: 101058371 Project acronym: ESTELLA Project title: Design of biobased thermoset polymer with recycling capability by dynamic bonds for bio-composite manufacturing Grant Agreement number: 101058371 Project acronym: ESTELLA Project title: Design of biobased thermoset polymer with recycling capability by dynamic bonds for biocomposite manufacturing Evaluation of recyclability of the developed matrices DELIVERABLE 4.1 Contractual Date of Delivery: 31 October 2024 Actual Date of Delivery: 29 October 2024 Lead contractor for this deliverable: FEYECON (FEY) Author(s): Maria F.P. Schonherr, Daniela Trambitas (FEY), Mª Dolores Ramirez (AND), , Natalia Biernat (ICSO), Filipa Vincente , Giorgio Tofani (NIC) Participants(s): FEY; AND ISCO, NIC WP contributing to the deliverable: WP 4 Nature: Confidential Version V. 5 Grant Agreement 101058371 Project ESTELLA ESTELLA-Deliverables_4.1.V5 ©ESTELLA - This is the property of ESTELLA Parties: shall not be distributed/reproduced without formal approval of ESTELLA General Assembly. therein. Executive Summary The work described in this report was focused on the recyclability of epoxy resin matrices developed within the Estella project by means of different recycling methods. The experiments were conducted in the project partners locations (FeyeCon (FEY), Andaltec (AND), Instytut Ciezkiej Syntezy Organicznej Blachownia (ICSO), and National Institute of Chemistry (NIC) in the period M17-M29. The deliverable exhibits some time deviations concerning the analysis of recycled materials and the optimization of recycling processes. This delay was caused by setbacks in epoxy matrices synthesis (work conducted in T2.2). Despite these limitations, no significant impact on the overall project implementation is anticipated. The completed work has successfully met its objectives as outlined in the grant agreement by identifying promising recycling methods and detailing the preliminary characteristics of recycled materials, thereby providing a solid foundation for continued efforts in Task 4.4. Objectives In the ESTELLA Project, Task 4.1 is described as follows: recyclability in order to select in T2.4 two matrices for the composite fabrication in T4.3 (one with the most exigent requirements and another with less demanding ones)". The main objectives of these tasks were to develop recycling methods that were tailored to break the covalent adaptable network uniquely present in each of the developed matrices and assess their recyclability based on the changes in their properties. For this purpose, scCO2-assisted and chemical recycling processes were selected to be investigated. Key outcomes 1. Diels-Alder resin (Composition: DGEBA+ furfurylamine+ BMI-689): a. scCO2-assisted recycling: The addition of scCO2induced swelling and foaming, accelerate the structural disintegration of the matrix and facilitates the dissolution of the resin (Figure 1). The recyclability assessment is still ongoing. Figure 1. DA resin: Original shape (left), after scCO2-assisted recycling: disintegrate (middle left), foamed (middle right) and dissolved (right) Grant Agreement 101058371 Project ESTELLA ESTELLA-Deliverables_4.1.V5 ©ESTELLA - This is the property of ESTELLA Parties: shall not be distributed/reproduced without formal approval of ESTELLA General Assembly. therein. b. Chemical recycling: Dissolution was observed when acidic solution (e.g., Cyrene/water/tartaric acid (TAR) or furfurylamine were used as solvent at processing temperature of 80-90 C (Figure 2). Figure 2. Diels-Alder resin dissolution in acidic solvents (left and middle) and furfurylamine (right) after treatment . 2. Epidian 6-based resin with various compositions developed by ICSO: The matrix can be either partially or totally dissolved mainly in glycol solvents. The recycling temperatures can vary significantly from 60 to 180 0C, depending on the presence or absence of additional co-solvent/catalyst and the initial cross linkers. The process involves evaporating the solvent using rotary evaporator and adding fresh crosslinker to the concentrated recycled resin, allowing the dissolved oligomers/monomers to be reused (Figure 3). Figure 3. Example of E-6-based resin dissolution in glycol (middle) and recycled resin concentrate (right) 3. NIC resin (Composition: Functionalized lignin + 1,4-Butanediol diglycidyl ether (B14DODGE): Despite similar CAN bond with ICSO resin, the recyclability of this sample was slightly different, only limited to no dissolution observed in glycol. The resin matrix can be recycled by using other types of solvents like bio-based dipolar heterocyclic cycloalkanones represented by Cyrene with acidic catalyst such as p-toluenesulfonic acid and TAR in combination with small amount of water (10% v/v) using a temperature ranged from 80-180 C. The recycled resin was able to be reshaped for the formation of new resin (Figure 4). Grant Agreement 101058371 Project ESTELLA ESTELLA-Deliverables_4.1.V5 ©ESTELLA - This is the property of ESTELLA Parties: shall not be distributed/reproduced without formal approval of ESTELLA General Assembly. therein. Figure 4. From left to right: original NIC resin, recycled resin, remoulded samples 1 (from exp 14) and 2 (from exp 18). 4. Characteristics of recycled resins: In general, changes in the thermal properties of recycled resins were observed. This observation is based on the decline of glass transition temperatures (all resin types) and melting temperature (DA resin). Not all the recycled materials have been analysed yet due to the delays in the delivery to the partners. Conclusions The results from Task 4.1 successfully demonstrated the feasibility of recycling epoxy matrices containing specific CAN bonds, developed by the Estella project partners within the promised timeline. This recyclability is evidenced by the dissolution of these resins in chemical solvents under milder conditions compared to conventional epoxy resins. However, further investigations are required to evaluate whether the key characteristics of these matrices, particularly their mechanical properties, can be effectively preserved after recycling. The subsequent work on these matters will be continue in Task 4.4 and going to be reported in more detailed in D4.4.