Recycling of end-of-use (EoU) or scraps aerospace composites produced during the manufacturing process have been the current trend followed for the past decade. Even though conventional recycling processes such as, shredding, pyrolysis, solvolysis are well established, these process does not consider the physical aspects like the fiber length, fiber orientation and the part-size of the composites. Previous researches on the conventional recycling of composites also report that the recycled fibers could able to reacquire 10-75 % of the mechanical performance compared to its initial state [1-4]. Hence, a circularity approach is necessary to recover and reuse these valuable thermoplastic composites in high-performance applications. Main challenges here are to separate the single fiber layer along with the matrix without any damage. Successful separation of glass-fibers embedded in a polypropylene matrix was performed by Imbert et al [5]. To reuse the composites in high-performance applications, these separated layers have to be bonded again to come to the initial state of the material or to be used as substitutes into other structural components to improve its loading-bearing capacity. Preliminary investigations on the recovery of carbon and glass fiber composites by ultrasonic assisted cutting and reconsolidated have been studied by Ragupathi et al [6,7]. However, a proof-of-concept was realised in the above-mentioned work, an in-depth analysis of the combination of US assisted cutting and reconsolidation still needs further clarifications. In this work, the propagation of crack during US cutting and the bonding mechanism w.r.t the oscillation amplitude, generator power and frequency from the welding system during the US reconsolidation will be presented for a better understanding on the process itself.

References:

[1] Gopalraj, S.K., Kärki, T., 2020. Review on the recycling of waste carbon fibre/glass fibre-reinforced composites: fibre recovery, properties and life-cycle analysis. SN Appl. Sci.

[2] Yang, Y., Boom, R., Irion, B., van Heerden, D.J., Kuiper, P., de Wit, H., 2012. Recycling of composite materials. Chem. Eng. and Proc.-Proc. Intensi. 51, 53–68. https://doi .org / 10 .1016 /j .cep .2011 .09 .007.

[3] Zhang, J., Chevali, V.S., Wang, H., Wang, C.H., 2020. Current status of carbon fibre and carbon fibre composites recycling. Composites, Part B, Eng. 193

[4] Zhu, J.H., Chen, P.Y., Su, M.N., Pei, C., Xing, F., 2019. Recycling of carbon fibre reinforced plastics by electrically driven heterogeneous catalytic degradation of epoxy resin. Green Chem. 21, 1635–1647. https://doi .org /10 .1039 /c8gc03672a.

[5] Imbert, M., Hahn, P., Jung, M., Balle, F., May, M., 2022. Mechanical laminae separation at room temperature as a high-quality recycling process for laminated composites. Mater. Lett. 306. https://doi .org /10 .1016 /j .matlet .2021 .130964.

[6] Balaji Ragupathi, Matthias Florian Bacher, Frank Balle, 2023a. First efforts on recovery of thermoplastic composites at low temperatures by power ultrasonics. Cleaner Materials 8. 10.1016/j.clema.2023.100186.

[7] Balaji Ragupathi, Matthias Florian Bacher, Frank Balle, 2023b. Separation and Reconsolidation of thermoplastic glass fiber composites by power ultrasonics. Resources, Conservation and Recycling 198. 10.1016/j.resconrec.2023.107122.