Chemical Recycling of Carbon Fiber Composites Via Alkaline Degradation and In Situ Self-Assembly of Functional Spheres

Abstract

An integrated upcycling strategy for waste carbon fiber-reinforced polymer composites (CFRP) is developed by coupling alkaline hydrothermal degradation with binder-free interfacial self-assembly. Under optimized conditions (25 wt % KOH, 200 °C, 8 h), selective ester cleavage yields clean carbon fibers and a degradation liquid rich in pH-responsive amphiphilic oligomers. These oligomers function as intrinsic dispersants, coagulants, and surface modifiers, enabling short reclaimed fibers to self-assemble into uniform porous spheres (2–4 mm) under mild mechanical stirring. The formation mechanism relies on oligomer adsorption, shear-induced aggregation, and energy-minimized spheroidization. Key parameters were optimized to achieve sphericity yields exceeding 85%. The resulting spheres possess a three-dimensional porous network and show considerable potential as catalyst supports, adsorbents, and lightweight thermal or conductive fillers. This one-pot, binder-free route establishes a viable pathway for high-value upcycling of CFRP waste.