Periodic Reporting for period 2 - REDONDO (REVERSIBLY DESIGNED CROSS LINKED POLYMERS)
Reporting period: 2024-03-01 to 2025-08-31
REDONDO (Reversibly Designed Cross linked Polymers) is a Horizon Europe project that aims to produce recyclable cross-linked polyethylene. Cross-linked polyethylene (PEX) is a difficult to recycle material due to the presence of very stable cross-links between the PE chains. REDONDO aims at developing a fully reversible cross-linking process to produce reversibly cross-linked polyethylene (rPEX), therefore enabling its recycling on demand.
PEX exhibits improved thermal stability, chemical resistance and structural integrity and is thus used in a number of applications for which polyethylene (PE) lacks temperature-related, strength-related, and other required properties. PEX has a wide variety of applications, notably as an insulation material for electric wires and cables and for hot and cold-water pipes and heating systems. Cross-linking modifies the nature of PE from thermoplastic to thermoset. As a result, PEX cannot be melted, as thermoplastics do, and recycled appropriately per application. It seems today that the only recycling technology for waste PEX scrap is grinding it to powder and directly moulding it with other thermoplastic blends as a filler, loosing most of its value.
REDONDO aims to achieve a fully reversible cross-linking process, that will enable the synthesis of reversibly cross-linked polyethylene (rPEX), that will be inherently recyclable and thus sustainable-by-design. Additionally, innovative biobased/green additives will be used to confer to rPEX novel/improved properties. Overall, rPEX will obtain significant added value due to its recyclability and its lower toxicity, compared to the use of traditional PVC-based polymeric materials or expensive and non-recyclable PEX. rPEX will be tested in two test-cases: pipes and photovoltaic cables. Complementarily, safety- and sustainability-by-design (SSbD) aspects will be incorporated to the design of the REDONDO products, while EoL scenarios will be investigated. Finally, two digital tools aiming at assisting stakeholders with SSbD concepts will be created: the additive inventory tool and the PLACE-me tool.
PEX exhibits improved thermal stability, chemical resistance and structural integrity and is thus used in a number of applications for which polyethylene (PE) lacks temperature-related, strength-related, and other required properties. PEX has a wide variety of applications, notably as an insulation material for electric wires and cables and for hot and cold-water pipes and heating systems. Cross-linking modifies the nature of PE from thermoplastic to thermoset. As a result, PEX cannot be melted, as thermoplastics do, and recycled appropriately per application. It seems today that the only recycling technology for waste PEX scrap is grinding it to powder and directly moulding it with other thermoplastic blends as a filler, loosing most of its value.
REDONDO aims to achieve a fully reversible cross-linking process, that will enable the synthesis of reversibly cross-linked polyethylene (rPEX), that will be inherently recyclable and thus sustainable-by-design. Additionally, innovative biobased/green additives will be used to confer to rPEX novel/improved properties. Overall, rPEX will obtain significant added value due to its recyclability and its lower toxicity, compared to the use of traditional PVC-based polymeric materials or expensive and non-recyclable PEX. rPEX will be tested in two test-cases: pipes and photovoltaic cables. Complementarily, safety- and sustainability-by-design (SSbD) aspects will be incorporated to the design of the REDONDO products, while EoL scenarios will be investigated. Finally, two digital tools aiming at assisting stakeholders with SSbD concepts will be created: the additive inventory tool and the PLACE-me tool.
During the second reporting period, important progress was achieved towards the objectives of REDONDO.
In WP3 rPEX was synthesised through two different routes and initial evaluation supports the development of these syntheses on a large scale to assess the processability of novel rPEX and its use in the selected end-user applications.
In WP4 the synthesis of several modified lignin-based and cellulose-based novel nanoadditives was developed/optimised, and HDPE composites with these additives were prepared to assess their impact on HDPE. Overall, promising properties were observed.
Regarding the processability of the composite materials (WP5), the incorporation of biobased nanofillers to HDPE and LDPE, on a larger scale compared to WP4, was extensively studied and challenges and mitigation actions were identified.
In WP6, the safety of the chemicals used in REDONDO was assessed, both in terms of hazard assessment and human health during production and processing.
In the context of WP7, LCA and LCC analyses were performed, recyclability of composites was assessed, the development of the additives' inventory and the place-me-tool are ongoing.
In WP8, competitors analysis and business cases for all industrial partners were drawn and a new YouTube channel has been set up to disseminate REDONDO’s results.
In WP3 rPEX was synthesised through two different routes and initial evaluation supports the development of these syntheses on a large scale to assess the processability of novel rPEX and its use in the selected end-user applications.
In WP4 the synthesis of several modified lignin-based and cellulose-based novel nanoadditives was developed/optimised, and HDPE composites with these additives were prepared to assess their impact on HDPE. Overall, promising properties were observed.
Regarding the processability of the composite materials (WP5), the incorporation of biobased nanofillers to HDPE and LDPE, on a larger scale compared to WP4, was extensively studied and challenges and mitigation actions were identified.
In WP6, the safety of the chemicals used in REDONDO was assessed, both in terms of hazard assessment and human health during production and processing.
In the context of WP7, LCA and LCC analyses were performed, recyclability of composites was assessed, the development of the additives' inventory and the place-me-tool are ongoing.
In WP8, competitors analysis and business cases for all industrial partners were drawn and a new YouTube channel has been set up to disseminate REDONDO’s results.
Significant progress has been achieved in the context of WP3, with the development of two different reversibly cross-linked polyethylene polymers.
After some optimisation, an rPEX based on Diels-Alder chemistry was developed and reversibility was evidenced over 110 °C. Gel content achieved was satisfactoty and rheoloical studies demonstrated the reversible character of cross-linking.
The second material developed was based on S-C-S bonds. Gel contents over 60% were achieved. The obtained rPEX materials were subjected to consecutive remelting ccles to evidence the reversibility of the cross-linking. The reprocessed materials were further characterised exhibiting only a small loss of mechanical properties.
After some optimisation, an rPEX based on Diels-Alder chemistry was developed and reversibility was evidenced over 110 °C. Gel content achieved was satisfactoty and rheoloical studies demonstrated the reversible character of cross-linking.
The second material developed was based on S-C-S bonds. Gel contents over 60% were achieved. The obtained rPEX materials were subjected to consecutive remelting ccles to evidence the reversibility of the cross-linking. The reprocessed materials were further characterised exhibiting only a small loss of mechanical properties.