End-to-end processing of recycled carbon fiber composites: From waste hydrogen tanks to mechanically enhanced additive-manufactured components

Abstract

The expanding applications of carbon-fiber-reinforced plastics (CFRP) in various industries have resulted in significant waste generation, creating an urgent need for effective CFRP recycling. However, there are few studies on end-of-life CFRP recycling or remanufacturing processes using recycled carbon fibers (rCF) from actual end-of-life products. This study comprehensively investigated the recycling process, remanufacturing, and post-processing of recycled CFRP (rCFRP) using rCF recovered from end-of-life hydrogen tanks through chemical oxidative recycling. The recovered rCF maintained 95 % tensile strength retention compared to virgin CF. The recovered rCFs were processed into rCF/acrylonitrile butadiene styrene (ABS) composites through rCF content adjustment and twin-screw extrusion for filament production, followed by material extrusion (MEX) fabrication. Thermal analysis revealed improved thermal stability, with an increased glass transition temperature from 101 to 103.7 °C, as the rCF content increased. A systematic evaluation of the rCF contents (5 and 10 wt%) demonstrated enhanced mechanical properties, with tensile strengths increasing from 31.4 to 37.6 MPa for filaments. However, void formation limited further performance enhancement. Post-processing through annealing at the optimized temperature effectively addressed these limitations by reducing porosity and enhancing interfacial bonding. The combined effect of 10 wt% rCF content and annealing resulted in optimal performance: tensile strength of 43.9 MPa and flexural strength of 70.7 MPa. To demonstrate industrial feasibility, automotive components were successfully fabricated through MEX using rCF/ABS composites. This comprehensive investigation demonstrates a viable approach for sustainable composite manufacturing, offering environmental benefits while enabling the production of complex customized parts for industrial applications. © 2025 Elsevier B.V., All rights reserved.