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Bio-based recyclable, reshapable and repairable (3R) fibre-reinforced EpOXY composites for automotive and construction sectors.

Periodic Reporting for period 3 - ECOXY (Bio-based recyclable, reshapable and repairable (3R) fibre-reinforced EpOXY composites for automotive and construction sectors.)

Reporting period: 2019-12-01 to 2020-11-30

Fibre reinforced thermoset composites (FRTCs) are attractive materials for high demanding sectors, such as automotive or construction, due to their lightweight and excellent mechanical properties. However, their lack of reprocessability and difficulty for repairing and recycling them significantly increases the overall material cost and causes grave environmental concerns. Additionally, the vast majority of polymer matrices and fibres used in their manufacturing are non-renewable fossil-derived materials or require high amounts of energy for their production.
Aiming at addressing those limitations by involving the European bio-based industry, ECOXY has developed innovative bio-based epoxy resins and fibre reinforcements to produce new sustainable and techno-economically competitive FRTCs by targeting advanced functionalities: reparability, reprocessability and recyclability (3R). The 3R functionalities were achieved by using new resin formulations replacing commonly used curing agents by dynamic hardeners, which under certain operational make possible to: 1) repair fibre/matrix delamination and matrix micro-cracks, 2) reprocess cured laminates to create new 3D parts, 3) mechanical and chemical recycling.
Thus, ECOXY developed: 1) tailor-made bio-based epoxy monomers, 2) upgraded and functional bio-based fibres (natural and PLA), 3) specific formulations for FRTCs manufacturing processes (WCM and pultrusion) and 4) additional functionalities such as flame-retardancy for 3R resin and self-healing for fibres.
The selected prototypes were validated for automotive and construction sectors using relevant standards and applicable certifications. Besides, an environmental (LCA) and socio-economic assessment of the results was carried out.
The well balanced composition of the consortium, 6 SME, 6 RTO and 1 academia gives ECOXY the maximum chance of success.
Specifications for demons, processes, and raw materials were defined in WP2. The seat back panel of the Lancia Y was chosen as the demo for the automotive sector, while a window profile was defined as the demo for construction. The requirements for their validation and demonstration of reshaping, repairing and recycling were defined and details of each of the process and product stages were given. Finally, bio-based fibers and resins that would be investigated in the project were defined considering their suitability for the composite manufacturing processes and targeted applications.
Based on the aforementioned specifications, bio-based fibers and fabrics were prepared, characterized and accordingly modified within WP3. In this context, flax-reinforcement structures with minimal curvature were produced by F&D as rovings and textiles. Similarly, PLA yarns and woven materials for reinforcement structures with improved properties in comparison to the existing ones were developed by CTB. All the reinforcements were sent for their use in WP4 and WP5.
Resins developed by SP in WP4 were divided in two groups: i) epoxy resins based on different vegetable oils; and ii) DGEVA (Diglycidyl Ether of Vanillyl Alcohol) and PHTE (Phloroglucinol Tris Epoxy), other bio-based epoxy precursors based on vanillyl alcohol and phloroglucinol respectively. All these resins were used by CID and UNICE within WP4 to prepare the targeted 3R bio-based thermoset resins and composites (with fibres and fabrics from WP3). Only the resins from the second group (DGEVA and PHTE) showed to fulfill the specifications defined in WP2 for the processing techniques and material properties and, therefore, the most suitable resin formulation based on these two (DGEVA:PHTE in a 60:40 ratio) was selected for its up-scaling and use in WP5 for the fabrication of demonstrator components.
The aforementioned resin formulation was selected as the one that best met the requirements of the final product. However, results showed that PLA fibre reinforcements were not appropriate for the defined application: the elevated Tg value (set by the requirements of the demonstrators) of the DGEVA:PHTE (60:40) mixture required too high reprocessing/recycling/repairing temperatures (PLA would melt at this T). Thus, the use of PLA fibre reinforcements would need to be left for applications with lower Tg requirements.
Within WP5 the selected demos for the automotive and the construction sectors were fabricated via conventional manufacturing techniques using the composite formulation developed in WP4. Demos for the automotive sector were manufactured by ICT through WCM technique, using the resins and fibre reinforcements developed within WP3 and WP4. Manufactured demos showed to be reprocessable by thermoforming at AITIIP. In the case of the window profile for the construction sector, some problems arose for the use of the developed materials and commercially available bio-based epoxy resin systems had to be used for their production by pultrusion in AIMPLAS. The obtained demos were validated by CRF and BGTec (end users of the automotive and construction sectors, respectively).
3R properties of the developed materials were studied in WP6. A complete study of the chemical and mechanical recycling of the prepared bio-based 3R thermosets, reprocessability and reparability was first done at a lab scale by CID and UNICE. These properties were also demonstrated at a semi-industrial scale and a flat laminate could be manufactured at AITIIP by hot-pressing the recycled material received from ECRT.
Sustainability analyses were performed within WP7 in order to address the three pillars of sustainability: i) LCA; ii) LCC; and iii) S-LCA. Due to their different synthesis scale, the most critical components from the environmental point of view showed to be PHTE and DGEVA. Both materials have to be further optimized to reduce their environmental impact. From the economic perspective it would also be critical as well to optimize the PHTE and DGEVA synthesis and scale their process up to an industrial level. The price of the components can compete with currently used materials, since the price increment can be compensated with the 3R, eco and natural sources labels.
Finally, dissemination and communication of the project results was done in WP8. Project logo, website, social networks, leaflet, stakeholder database…were created at the beginning on the project in order to support these tasks. A total of 10 scientific papers have been published and consortium members have attended to several conferences throughout the life of the project. Exploitation strategies and IPR management were also studied and described within this WP: 3 KERs were identified by the end of the project.
Epoxy resins from natural resources have been succesfully developed within the project as a suitable alternative for the most widely used epoxy resin (DGEBA, based on Bisphenol A). These resins, combined with the selected dynamic hardeners gave the target bio-based polymer matrix with advanced 3R functionalities allowing (re)processing, repairing and recycling while keeping their functional properties (something that is not possible with conventional thermoset materials). By the end of the project, the most promising formulation (comparable to DGEBA in terms of thermomechanical properties) was upscaled and the defined demos were succesfully manufactured and validated.
Natural and bio-based fibres have been developed too for using them as reinforcements of the aforementioned 3R polymer matrix.