Circularity of thermoplastic ComposIte wound stRuCtUres through innovative materiaL design, peeling-based disAssembly and Re-winding – CIRCULAR2

Thermoplastic composite winding enables the manufacturing of lightweight tanks particularly suited for the transportation sector. Nevertheless, a classical recycling without downcycling of these structures made of valuable tapes made of continuous fibers embedded in a polymeric matrix is a major technical and economical challenge. In order to retain the value of the composite, the end-of-usage processing should preserve the continuity of the fibers to maximize the mechanical properties and maintain the fibers embedded in the matrix to simplify reuse. Recent experimental results have demonstrated the ability of peeling-based disassembly to reach these goals and have highlighted the decisive role of the interlaminar properties on the quality of the recovered material. Building on these results, the aim of the project Circular² is to enable material circularity of thermoplastic composite wound structures through innovative material design, peeling-based disassembly and tape reprocessing using a holistic design for reuse approach. Two innovative design strategies will be investigated: (A) material-focused design consisting in tuning the tape surface to induce the desired interface properties under dedicated thermo-mechanical loading; (B) structure-focused winding design consisting in avoiding peeling-disadvantageous fiber nesting of adjacent layers; in combination with two innovative disassembly strategies: (I) ultrasonic-assisted peeling; (II) peeling at low temperature or high peeling rate to induce an embrittlement of the layer to layer interface. Peeled tapes will be reused in a winding process. The mechanical performance will be determined after manufacturing, peeling and reuse of the tape material. A multi-physics and multi-scale simulation tool will be developed to model the mechanisms involved during the different processes. Finally, the environmental footprint of the investigated strategies will be compared.