Advances in carbon and glass fiber recycling: optimal composite recycling and sustainable solutions for composite waste

The increasing industrial use of carbon and glass fiber-reinforced polymer (FRP) composites, coupled with growing landfill restrictions, has necessitated the development of efficient recycling and remanufacturing technologies. This review presents a comprehensive analysis of state-of-the-art engineering and process optimization techniques employed in the recycling of FRP composites, with a focus on mechanical, thermal, chemical, and emerging advanced recycling methods. Carbon and glass fiber composites are extensively used across sectors, such as aerospace, automotive, construction, and sports, resulting in substantial waste generation during both manufacturing and end-of-life phases. The recovery and reuse of reinforcement fibers, particularly in renewable energy sectors, pose significant technical and environmental challenges. This paper evaluates recent progress in composite recycling strategies, including the remanufacturing potential of recovered fibers, and provides a comparative assessment of recycled versus virgin materials. It also highlights the environmental benefits of recycling over conventional end-of-life options, such as landfilling and energy recovery. While mechanical recycling is relatively established, its effectiveness in fiber reclamation is limited. In contrast, advanced methods, such as pyrolysis and solvolysis, offer superior recovery quality but face economic and scalability constraints. Emerging technologies—including high-voltage fragmentation (HVF) and solvent-based chemical processes—demonstrate promising potential for sustainable and energy-efficient fiber recovery. The findings underscore the importance of continued innovation, technological optimization, and supportive policy frameworks in advancing composite recycling toward a circular economy.