Material requirements for recycling processes

Grant Agreement number: 101058371 Project acronym: ESTELLA Project Design of biobased thermoset polymer with recycling capability by dynamic bonds for bioGrant Agreement number: 101058371 Project acronym: ESTELLA Project title: Design of bio-based thermoset polymer with recycling capability by dynamic bonds for bio-composite manufacturing DELIVERABLE 1.4 Material requirements for recycling processes Contractual Date of Delivery: 31 08 2022 Actual Date of Delivery: 03.10.2022 Lead contractor for this deliverable: ULE Author(s): Carlos Barreiro (ULE) Participants(s): Tonje M. B. Heggeset (SINT); Simone Balzer Le (SINT); Julia Guerrero (CID); Antonio Peñas (AND); Daniela Trambitas (FEY); María López Abelairas (IDE); Damian Kiełkiewicz (ICSO) WP contributing to the deliverable: WP 1 Nature: Public Version V. 03 Grant Agreement 101058371 – Project ESTELLA ESTELLA_D1.4 ©ESTELLA - This is the property of ESTELLA Parties: shall not be distributed/reproduced without formal approval of ESTELLA General Assembly. This reflects only the author’s views. The Community is not liable for any use that may be made of the information contained therein. REVISION TABLE Document version Date Modified sections - Details V1 16.09.2022 First draft V2 23.09.2022 Second version after technical review (ULE, IDE, SINT, AND, CID, ICSO) V3 30.09.2022 Final version Grant Agreement 101058371 – Project ESTELLA ESTELLA_D1.4 ©ESTELLA - This is the property of ESTELLA Parties: shall not be distributed/reproduced without formal approval of ESTELLA General Assembly. This reflects only the author’s views. The Community is not liable for any use that may be made of the information contained therein. Table of Contents TABLE OF CONTENTS .................................................................................................................... 3 ABBREVIATIONS ........................................................................................................................... 4 EXECUTIVE SUMMARY .................................................................................................................. 5 1. RECYCLABILITY OF THERMOSET COMPOSITES ................................................................... 6 2. TASK 1.4: DEFINITION OF RECYCLABILITY TARGET CONDITIONS ..................................... 7 3. RECYCLING SCENARIOS AND PROCEDURES .................................................................... 7 4. GENERAL GUIDE OF THE ESTELLA RECYCLING PROCESS .................................................. 9 5. DELIVERABLE 1.4 RECOMMENDATIONS ........................................................................... 11 BIBLIOGRAPHY ........................................................................................................................... 12 Grant Agreement 101058371 – Project ESTELLA ESTELLA_D1.4 ©ESTELLA - This is the property of ESTELLA Parties: shall not be distributed/reproduced without formal approval of ESTELLA General Assembly. This reflects only the author’s views. The Community is not liable for any use that may be made of the information contained therein. Abbreviations DSP: Downstream Processing GMO: Genetically Modified Organisms PET: Polyethylene terephthalate scCO2: Super Critical CO2 Grant Agreement 101058371 – Project ESTELLA ESTELLA_D1.4 ©ESTELLA - This is the property of ESTELLA Parties: shall not be distributed/reproduced without formal approval of ESTELLA General Assembly. This reflects only the author’s views. The Community is not liable for any use that may be made of the information contained therein. Executive Summary Deliverable 1.4 presents the possible scenarios for thermoset fibre reinforced polymer composites recycling, different approaches (biotechnological, chemical, and mechanical) and provides a guide of conditions to reach the final recycling target process of ESTELLA as a sequential combination of these approaches. D1.4 is highly relevant for the subsequent tasks related to the thermoset material recyclability because of it condition the manufacturing and the recycling procedures. This deliverable fully covers the requirements of task 1.4 of WP1 in content and fulfilment. Its submission delay has been the result of the starting date of the project and the holiday periods of the partners (Northern Europe in July, Southern Europe in August), which delayed the results coordination, the critical review by the participants, and the writing process. Grant Agreement 101058371 – Project ESTELLA ESTELLA_D1.4 ©ESTELLA - This is the property of ESTELLA Parties: shall not be distributed/reproduced without formal approval of ESTELLA General Assembly. This reflects only the author’s views. The Community is not liable for any use that may be made of the information contained therein. 1. Recyclability of thermoset composites Thermosetting polymeric composites are widely used in almost all industrial sectors (construction, aeronautics, automotive, renewable energy, sports) where lightness and high mechanical performance (dimensional stability, environmental resistance and durability) are required. Nowadays, epoxy resins obtained from fossil resources are the polymeric matrix used for these composite materials due to their good combination of processability and thermomechanical performance (1). A thermosetting polymer, resin, or plastic, often simply called as thermosetting, is a polymer that irreversibly hardens when it is subjected to a curing process from a prepolymer or resin, which is a soft solid, or viscous liquid (2). Curing is induced by heat, suitable irradiation, or both, and can also be enhanced by high pressure or by mixing with a catalyst (3). However, their main fortress, durability, also intrinsically involves their principal disadvantage, which is their poor recyclability. Due to the crosslinked microstructure that is generated along the curing process, thermosetting compounds are not readily available for reprocessing or recycling, which means that after their useful life, disposal is often the only alternative. Thus, although some recycling techniques are already available, these methods are often energy intensive and not a long-term sustainable solution, or significantly reduce the qualities of the material, limiting its further applications. Thermosetting polymeric composites usually have, at least, two components: i) polymeric matrix and ii) reinforcement (2,4–6). The matrix is made of the epoxy materials mentioned above, while the reinforcements are made of fibres (synthetic or natural), which very often is what recovery techniques only focus on, as it can be the most valuable element, discarding the polymer matrix (7). Thus, at the end of their useful life, most thermosetting compounds end up burned or accumulated in landfills, triggering environmental and health problems. Finally, only a small percentage (<10%) reaches the recycling processes. Integration of biological components in the thermosetting composites is paving the way for the application of biotechnological solutions [e.g., native microorganisms, GMO (Genetically Modified Organisms), enzymes, …]. Thus, little by little these biotechnological recycling routes are making their way as an innovative alternative process for plastic waste recycling by using bacteria to break down plastics, reducing their environmental impact and boosting the economy by offering new opportunities in the waste management sector. Recent studies such as the isolation of the polyethylene terephthalate (PET) degrading bacterium, Ideonella sakaiensis (8), or the description of the caterpillars of the wax moth (Galleria mellonella) (9) as polyethylene degraders, Grant Agreement 101058371 – Project ESTELLA ESTELLA_D1.4 ©ESTELLA - This is the property of ESTELLA Parties: shall not be distributed/reproduced without formal approval of ESTELLA General Assembly. This reflects only the author’s views. The Community is not liable for any use that may be made of the information contained therein. possibly due to its microbiota, have promoted research on the biotechnological degradation (microorganisms, enzymes) of plastic, as well as the search for new microbial and enzymatic activities that allow it. 2. Task 1.4: Definition of Recyclability Target Conditions Task 1.4 is focused on the recycling conditions that thermoset composites developed in ESTELLA will have to meet [confinement, collection of materials, particle size required (shredding)] to reach a successful recycling process. The task, and its subsequent deliverable (D1.4), is aimed to provide the guidelines that should be directing composites recycling. This task is the result of the collaboration of the different partners involved in WP1 (ULE, IDE, SINT, WR, NIC, ICSO, FEY, ECRT, AND, CID). 3. Recycling scenarios and procedures Two different concepts must be considered in this deliverable:  Thermoset degradation, pointing to the complete degradation of the polymer [e.g., by enzymatic, microbiological (using natural isolates or genetically modified organisms, GMO), and/or chemical processes]. For example, enzymatic processes are often slow and the reaction rates need to be improved.  Thermoset recycling (total/partial) refers to breaking down the polymer into useful building blocks that can be reused (not necessarily as the same product). In addition, three main questions help to define the possible recycling scenarios: • What do we want to obtain as recycling product? • Where can we do it? • How can we do it? The following summary tables condense different aspects of the proposed approaches of ESTELLA. Grant Agreement 101058371 – Project ESTELLA ESTELLA_D1.4 ©ESTELLA - This is the property of ESTELLA Parties: shall not be distributed/reproduced without formal approval of ESTELLA General Assembly. This reflects only the author’s views. The Community is not liable for any use that may be made of the information contained therein. Trying to answer the proposed questions, possible recycling scenarios can be as follows: Epoxy final fate Degradation Recycling (total / partial) Being able to fully degrade the reinforced epoxy composites to basal molecules NH3 and/or CO2 (depending on the composition). The contaminant epoxy material is taken out of circulation and no byproducts or composite components will be recovered. Being able to recover natural fibres, epoxy resins, precursors, mixtures of them or by-products of the process. Partial degradation of the thermoset composites could be needed. Recovery of products with intrinsic economic value --- +++ / ++ Based on these recovery possibilities, the location of the material to be recycled or degraded would be determined: Location of material: recycling conditions Fully confined (e.g., fermenter) Partially confined (e.g., recycling plant area) Contaminated environment This is the scenario suitable for GMO (genetically modified organisms) and/or enzyme addition Natural isolated microorganisms (no GMO) and enzymes (e.g., powder) Natural isolated microorganisms (no GMO) and enzymes (e.g., powder) Controlled recovery of products with intrinsic economic value +++ ++ --- Control over conditions of the process Fully controlled Partially controlled Uncontrolled The biotechnological developments included in the ESTELLA application should be in concordance with the recycling conditions: Biotechnological degradation (Microorganisms / Enzymes) Wild type microorganisms GMO microorganisms Enzymes Natural isolates can be used under confined and not confined conditions Mandatory: controlled and confined conditions must be applied Free environmental application could be feasible Recovery of by-products or thermoset component Conditioned to the application location Grant Agreement 101058371 – Project ESTELLA ESTELLA_D1.4 ©ESTELLA - This is the property of ESTELLA Parties: shall not be distributed/reproduced without formal approval of ESTELLA General Assembly. This reflects only the author’s views. The Community is not liable for any use that may be made of the information contained therein. Mechanical recycling implies the design of a pipeline boarding different procedures to reach a suitable process: Mechanical recycling Grinding process Fractions separation Reduction of material volume by cutting, shredding, and crushing Material classification (cyclones, sieves) and separation in different fractions for material enrichment (fibreand/or resin-enriched fractions) Recovery thermoset component A thin powder fraction with a higher proportional amount of fiber and polymer than the original composite Chemical recycling methodologies must address several aspects of the composite: Chemical recycling Temperature conditions Depolymerization strategies Mechanical properties Specific issues To avoid thermal degradation of natural fibres, temperatures below 160-200 ºC should be used Depolymerized product obtaining should be feasible both at laboratory and industrial level Mechanical properties of discontinuous fibre could require previous shredding steps -Fibre layers should be easily delaminated -Depolymerization work-up conditions should be feasible -Resin-fibre adhesion should be controlled Recovery thermoset component Proper integration of all requirements will support the chemical recycling process of each valuable component (fibres, polymers or valuable by-products) 4. General guide of the ESTELLA recycling process The presented scenarios and concerns regarding the recycling processes provide the answers to the initially proposed questions aimed to recover: i) fiber (by degradation of resins); ii) epoxy resin (by degradation of fibers); iii) both (partial degradation of each compound); or (iv) interesting by-products. What do we want to obtain as recycling product? The main aim of the recycling process is to obtain fibres and epoxy resin. This way, one or both fractions can be reused to obtain new materials. If any, a limited degradation in each fraction can be carried out, which would allow the reuse of both.