Vitrimer-Based Composites: Enabling Repairable, Recyclable Propellers

Within the TorPropel project, we are shaping the future of aircraft propellers at the intersection of advanced composite materials, sustainability, and repair-oriented design. Our work focuses on the development of toroidal propellers using innovative vitrimer-based materials, enabling lighter structures, extended service life, and significantly simplified repair processes — all without the need for autoclave manufacturing.

Aerospace-grade composites provide exceptional strength-to-weight ratios, contributing to improved aircraft performance through weight reduction and enhanced fuel efficiency. At the same time, composite repair technologies have evolved, with methods such as scarf joining and patch repair allowing structural integrity to be restored without compromising performance. Recent advances in thermoset chemistry, particularly vitrimer resins, further simplify repair processes by combining the advantages of traditional thermosets (processing conditions and mechanical properties) with thermoplastic-like features such as recyclability, re-processability, welding, and enhanced repairability.

Within TorPropel, novel vitrimer tapes based on the 3R system are being developed for the rapid production of toroidal propellers that are both easy to repair and intrinsically recyclable. These tapes can be processed in the so-called “enduring state”, reached a few days after production at room temperature, during which the glass transition temperature stabilizes between 50 °C and 60 °C and remains stable for more than 200 days. Enduring tapes can be stored at room temperature and used at any degree of curing, addressing one of the major challenges faced by the aeronautical industry: limited shelf life and demanding storage conditions of conventional composite materials. The materials will also be optimized to extend propeller lifecycle and eliminate the need for autoclave-based manufacturing and repair.

Following experimental testing, structural analyses of toroidal propeller demonstrators will be conducted using advanced non-destructive inspection techniques, including ultrasonic testing and thermography, to detect internal or surface damage under simulated operational conditions. In parallel, the feasibility and effectiveness of composite repair methodologies will be assessed, leveraging the intrinsic repairability of vitrimer-based tapes.

Finally, standardized repair procedures will be developed by GMI AERO, building on existing aeronautical protocols. Proprietary curing and pneumatic equipment, including ANITA hot bonders and the OLGA positive pressure application device, will be adapted to ensure compliant, efficient, and reliable repair of toroidal composite propellers.