Recovery of carbon fiber from carbon fiber reinforced plastics using alkali molten hydroxide

Abstract High-strength carbon fibers were recovered by a new method, involving the decomposition of the thermosetting resin part of carbon fiber-reinforced plastic (CFRP) by heating it in a mixture of sodium hydroxide (NaOH) and potassium hydroxide (KOH). Alkali molten hydroxide was prepared by heat...

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Main Authors: Takaaki Wajima, Kazuki Yamashita
Format: Article
Language:English
Published: Nature Portfolio 2025-01-01
Series:Scientific Reports
Subjects:
Online Access:https://doi.org/10.1038/s41598-024-84293-4
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author Takaaki Wajima
Kazuki Yamashita
author_facet Takaaki Wajima
Kazuki Yamashita
author_sort Takaaki Wajima
collection DOAJ
description Abstract High-strength carbon fibers were recovered by a new method, involving the decomposition of the thermosetting resin part of carbon fiber-reinforced plastic (CFRP) by heating it in a mixture of sodium hydroxide (NaOH) and potassium hydroxide (KOH). Alkali molten hydroxide was prepared by heating the mixture of NaOH and KOH at various ratios (NaOH: KOH = 1:0, 3:1, 1:1, 1:3, 0:1) at 400oC, and the CFRP was then heated with the aforementioned alkali molten hydroxide under a nitrogen atmosphere at 200–400oC for 0–90 min. Subsequently, the CFRP was washed with distilled water and filtered to recover the carbon fibers, and its tensile strength was estimated. Carbon fibers with higher strength can be recovered by heating the CFRP with an alkali molten hydroxide. As the temperature increased, the strength of the recovered carbon fiber decreased owing to the increase in gas generation caused by the decomposition of the thermosetting resin and carbon fiber in the molten hydroxide, such as H2 and CH4. KOH increase in the alkali molten hydroxide promoted decomposition of the resin, whereas the fiber was degraded. High-strength carbon fiber, nearly the same as virgin fiber, can be recovered at 200oC using the NaOH: KOH molten hydroxide at a ratio of 1:3.
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spelling doaj-art-f621e2a8e3404615ad5d1fbd76a055ba2025-01-05T12:20:37ZengNature PortfolioScientific Reports2045-23222025-01-011511810.1038/s41598-024-84293-4Recovery of carbon fiber from carbon fiber reinforced plastics using alkali molten hydroxideTakaaki Wajima0Kazuki Yamashita1Department of Materials Science, Graduate School of Engineering, Chiba UniversityDepartment of Materials Science, Graduate School of Engineering, Chiba UniversityAbstract High-strength carbon fibers were recovered by a new method, involving the decomposition of the thermosetting resin part of carbon fiber-reinforced plastic (CFRP) by heating it in a mixture of sodium hydroxide (NaOH) and potassium hydroxide (KOH). Alkali molten hydroxide was prepared by heating the mixture of NaOH and KOH at various ratios (NaOH: KOH = 1:0, 3:1, 1:1, 1:3, 0:1) at 400oC, and the CFRP was then heated with the aforementioned alkali molten hydroxide under a nitrogen atmosphere at 200–400oC for 0–90 min. Subsequently, the CFRP was washed with distilled water and filtered to recover the carbon fibers, and its tensile strength was estimated. Carbon fibers with higher strength can be recovered by heating the CFRP with an alkali molten hydroxide. As the temperature increased, the strength of the recovered carbon fiber decreased owing to the increase in gas generation caused by the decomposition of the thermosetting resin and carbon fiber in the molten hydroxide, such as H2 and CH4. KOH increase in the alkali molten hydroxide promoted decomposition of the resin, whereas the fiber was degraded. High-strength carbon fiber, nearly the same as virgin fiber, can be recovered at 200oC using the NaOH: KOH molten hydroxide at a ratio of 1:3.https://doi.org/10.1038/s41598-024-84293-4CFRPCarbon fiber recoveryAlkali molten hydroxideResin decompositionTensile strength
spellingShingle Takaaki Wajima
Kazuki Yamashita
Recovery of carbon fiber from carbon fiber reinforced plastics using alkali molten hydroxide
Scientific Reports
CFRP
Carbon fiber recovery
Alkali molten hydroxide
Resin decomposition
Tensile strength
title Recovery of carbon fiber from carbon fiber reinforced plastics using alkali molten hydroxide
title_full Recovery of carbon fiber from carbon fiber reinforced plastics using alkali molten hydroxide
title_fullStr Recovery of carbon fiber from carbon fiber reinforced plastics using alkali molten hydroxide
title_full_unstemmed Recovery of carbon fiber from carbon fiber reinforced plastics using alkali molten hydroxide
title_short Recovery of carbon fiber from carbon fiber reinforced plastics using alkali molten hydroxide
title_sort recovery of carbon fiber from carbon fiber reinforced plastics using alkali molten hydroxide
topic CFRP
Carbon fiber recovery
Alkali molten hydroxide
Resin decomposition
Tensile strength
url https://doi.org/10.1038/s41598-024-84293-4
work_keys_str_mv AT takaakiwajima recoveryofcarbonfiberfromcarbonfiberreinforcedplasticsusingalkalimoltenhydroxide
AT kazukiyamashita recoveryofcarbonfiberfromcarbonfiberreinforcedplasticsusingalkalimoltenhydroxide