Recent Advancements in Chemical Valorization of Legacy and Emerging Fiber-Reinforced Polymer Composites

Fiber-reinforced polymer (FRP) composites are increasingly crucial in the global effort to shift toward sustainable energy sources and more fuel-efficient transportation technologies. These materials are excellent in service; however, poor end-of-life (EoL) recycling options compromise the sustainability of FRPs. Current methods, including pyrolysis and mechanical recycling, are inadequate at preserving value from the fibers or polymers. By contrast, chemical recycling methods demonstrate promise to recover high-value fibers and chemicals from composite materials. Novel, chemically engineered resin systems further enable fiber/matrix separation to facilitate the recycling process. Particularly within the past 5 years, there has been a growing interest in targeting monomer recovery from composite matrices. This review provides a comprehensive overview of recent developments in selective depolymerization of current (legacy) composite materials and strategies for facile polymer disconnection in novel resin systems. Advantages and limitations across recycling strategies for both legacy and novel composites underscore key remaining challenges in composite sustainability.