We have developed a chemical recycling method for carbon fiber reinforced plastics (CFRP) using the nitric acid decomposition method. While recycling of carbon fiber (CF) in CFRP has been widely studied, reports focusing on the chemical recycling of the CFRP’s resin matrix remain scarce. Only a limited number of studies have explored the chemical recycling of the thermosetting resin component in CFRP. In this study, we targeted the resin fraction of epoxy-based prepreg of CFRP and successfully decomposed it under mild conditions (80 °C) in a short process time (3 hours) using nitric acid. This process enabled the efficient separation and recovery of carbon fiber with minimal damage, while also allowing for the isolation of the decomposed resin fragments. Characterization of the decomposed resin products revealed the formation of nitro-containing aromatic compounds. Subsequent catalytic hydrogenation of these nitroaromatics yielded amine-functionalized compounds, which were evaluated as potential curing agents of epoxy resins. Low-level substitution of commercial amine hardener is feasible under the present formulation, whereas higher-level substitution led to precipitation and decreased flexural strength. This approach not only enables the recycling of both carbon fibers and the resin matrix in CFRP but also provides a pathway to convert the resin fraction into functional intermediates for polymer synthesis. This study provides a laboratory-scale proof of concept for simultaneous fiber recovery and upcycling.
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