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OAJRC Material Science

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ArticleOpen Access http://dx.doi.org/10.26855/oajrcms.2026.06.002

Recycling of Epoxy Resin in CFRP Prepreg Using Nitric Acid Decomposition Method

Naoki Mori1, Winarto Kurniawan2, Masatoshi Kubouchi1,*, Saiko Aoki1

1School of Materials and Chemical Technology, Institute of Science Tokyo, 2-12-1, Ookayama, Meguro-ku Tokyo 152-8552, Japan.

2Department of Chemical and Biological Engineering, School of Creative System Engineering, National Institute of Technology Akita Col-lege, 1-1 Iijimabunkyocho, Akita 011-8511, Japan.

*Corresponding author: Masatoshi Kubouchi

Published: May 27, 2026

Abstract

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.

Keyword

CFRP prepreg recycling; Chemical recycling; Epoxy resin decomposition; Nitric acid; Carbon fiber recovery

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Copyright

© 2026 by the author(s).
This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives (CC BY-NC-ND) license, which permits non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited and is not modified or adapted.
https://creativecommons.org/licenses/by-nc-nd/4.0/

How to cite this paper

Recycling of Epoxy Resin in CFRP Prepreg Using Nitric Acid Decomposition Method

How to cite this paper: Naoki Mori, Winarto Kurniawan, Masatoshi Kubouchi, Saiko Aoki. (2026) Recycling of Epoxy Resin in CFRP Prepreg Using Nitric Acid Decomposition MethodOAJRC Material Science8(1), 12-20.

DOI: http://dx.doi.org/10.26855/oajrcms.2026.06.002