Industrial-scale recycling of closed-loop carbon fiber composites: pyrogasification and fiber reuse

The transition toward a circular economy constitutes a critical priority for advanced manufacturing, particularly in the domain of composite materials, whose intrinsic structural complexity and thermoset matrices severely limit end-of-life recovery. Carbon-fiber-reinforced polymers (CFRPs), extensively employed in aerospace and automotive industries due to their high specific strength and durability, present significant environmental and economic challenges once decommissioned. This research addresses these issues through a dual and complementary strategy: the industrial-scale recovery of carbon fibers via pyro-gasification and the molecular design of recyclable thermoreversible matrices compatible with recycled reinforcements. The first research stream concerns the implementation and optimization of a continuous pyro-gasification process for composite waste treatment. The integrated system combines thermal decomposition and controlled oxidation to selectively remove the polymeric matrix while preserving fiber morphology and mechanical integrity. Operating parameters, including temperature profiles and residence times, were systematically optimized to minimize oxidative degradation. The process achieves recovery efficiencies exceeding 98 wt%, producing high-purity recycled fibers with carbon content above 97% and tensile strength retention approaching that of virgin counterparts. Morphological analyses confirmed complete matrix removal under optimized conditions, while single-fiber tensile testing demonstrated substantial preservation of stiffness and strength. Life cycle assessment further quantified the environmental benefits, indicating a marked reduction in carbon footprint compared with primary fiber production. The second research stream focuses on the development of a thermoreversible polymer matrix based on Diels–Alder chemistry between a functionalized polyketone and a bio-based bismaleimide. By tailoring crosslink density, the resulting networks exhibit tunable thermo-mechanical properties and reversible behavior, with retro-Diels–Alder transitions enabling controlled network dissociation. Composites reinforced with recycled carbon fibers display mechanical stability and effective property retention over multiple recycling cycles. Overall, the integration of scalable recycling technology and reversible polymer chemistry demonstrates the feasibility of a closed-loop lifecycle for high-performance composite systems.