Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Preparation of carbon fibers coated with epoxy sizing agents containing degradable acetal linkages and synthesis of carbon fiber-reinforced plastics (CFRPs) for chemical recycling

Abstract

New epoxy resins containing degradable acetal linkages were synthesized by the addition reaction of bisphenol-A (BA) and epoxy-functionalized vinyl ethers containing hydrophilic oxyethylene chains, 2-(vinyloxy)ethyl glycidyl ether (VEGE) and 2-[2-(vinyloxy)ethoxy]ethyl glycidyl ether (VEEGE). Carbon fibers were applied with the obtained degradable epoxy resin-based sizing agents (designated as BA-VEGE and BA-VEEGE) in ordinary (1.4 ~ 2.2 wt%) or excess (6.4 ~ 13.4 wt%) amounts. Interfacial adhesion between the carbon fibers applied with the degradable epoxy resin-based sizing agents and matrix resins (bisphenol-A-type epoxy resin) was evaluated by the microdroplet method. Carbon fibers with both degradable epoxy resins as a sizing agent showed improved adhesive properties compared with the desized carbon fibers. Using the degradable sizing agent-applied carbon fibers, carbon fiber-reinforced plastics (CFRPs) were prepared by laminating prepreg sheets and heating them under pressure. The tensile properties of the CFRPs with [0]50 lay-up did not depend on the structure of the sizing agents, but the tensile strength decreased as the amount of sizing agent used increased. On the other hand, the tensile properties of the CFRPs with [0/90]12S lay-up were not dependent on the structure or volume of sizing agents used. The impact toughness of the CFRPs was evaluated by the charpy impact test. When an ordinary volume of sizing agent was applied, the CFRPs with degradable epoxy resin-based sizing agents exhibited higher levels of impact strength than the commercial sizing agent-based CFRPs. However, applying an excessive volume of sizing agent to carbon fibers led to a decline in impact strength. The degradation reaction was conducted under acidic conditions by the treatment of HCl at room temperature or 70 °C. CFRPs with degradable epoxy resins as sizing agents in ordinary volumes were barely decomposed due to insufficient degradable regions in the CFRP components. However, the CFRPs applied with excess degradable sizing agents decomposed and carbon fibers were recovered.

This is a preview of subscription content

Access options

Buy article

Get time limited or full article access on ReadCube.

$32.00

All prices are NET prices.

Scheme 1
Scheme 2
Scheme 3
Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10
Fig. 11
Fig. 12

References

  1. Nakanishi Y, Ikuta N. Interphase of FRP and its chemical. Control J Soc Mat Sci Jpn. 1996;45:1307.

    CAS  Article  Google Scholar 

  2. Tsujioka N, Maekawa Z, Hamada H, Hojo M. Effect of surface oxidation and sizing treatment of carbon fiber on interfacial adhesion. J Soc Mat Sci, Jpn. 1997;46:163.

    CAS  Article  Google Scholar 

  3. Cao X, Wen YF, Zhang SC, Yang YG. A heat resistant emulsifying sizing agent for carbon fibers. New Carbon Mater. 2006;21:337.

    CAS  Google Scholar 

  4. Zhang RL, Huang YD, Liu L, Tang YR, Su D, Xu LW. Effect of emulsifier content of sizing agent on the surface of carbon fibres and interface of its composites. Appl Surf Sci. 2011;257:3519.

    CAS  Article  Google Scholar 

  5. Zhang RL, Huang YD, Liu L, Tang YR, Su D, Xu LW. Effect of the molecular weight of sizing agent on the surface of carbon fibres and interface of its composites. Appl Surf Sci. 2011;257:1840.

    CAS  Article  Google Scholar 

  6. Guo H, Huang Y, Liu L, Shi X. Effect of epoxy coatings on carbon fibers during manufacture of carbon fiber reinforced resin matrix composites. Mater Des. 2010;31:1186.

    CAS  Article  Google Scholar 

  7. Yamaguchi K, Kitano A. Development in composites technology for reduction of environmental load II: recycle method for CFRP. J Soc Mat Sci Jpn. 2008;57:747.

    CAS  Article  Google Scholar 

  8. Pickering SJ. Recycling technologies for thermoset composite materials-current status, Compos. Part A Appl Sci Manuf. 2006;37:1206.

    Article  Google Scholar 

  9. Okajima I, Hiramatsu M, Shimamura Y, Awaya T, Sako T. Chemical recycling of carbon fiber reinforced plastic using supercritical methanol. J Supercrit Fluids. 2014;91:68.

    CAS  Article  Google Scholar 

  10. Liu Y, Liu J, Jiang Z, Tao T. Chemical recycling of carbon fibre reinforced epoxy resin composites in subcritical water: Synergistic effect of phenol and KOH on the decomposition efficiency. Polym Degrad Stabil. 2012;97:217.

    Google Scholar 

  11. Bai Y, Wang Z, Feng L. Chemical recycling of carbon fibers reinforced epoxy resin composites in oxygen in supercritical water. Mater Des. 2010;31:999.

    CAS  Article  Google Scholar 

  12. Luzuriaga ARD, Martin R, Markaide N, Rekondo A, Cabañero G, Rodríguez J, et al. Epoxy resin with exchange disulfide crosslinks to obtain reprocessable, repairable and recyclable fiber-reinforced thermoset composite. Mater Horiz. 2016;3:241.

    Article  Google Scholar 

  13. Luzuriaga ARD, Matxian JM, Ruipérez F, Martin R, Asua JM, Cabañero G, et al. Transient mechanochromism in epoxy vitrimer composites containing aromatic disulfide crosslinks. J Mater Chem C. 2016;4:6220.

    Article  Google Scholar 

  14. Yuan Y, Sun Y, Yan S, Zhao J, Liu S, Zhang M, et al. Multiply fully recyclable carbon fibre reinforced heat-resistant covalent thermosetting advanced composites. Nat Commun. 2017;8:14657.

    Article  Google Scholar 

  15. Wang Y, Cui X, Ge H, Yang Y, Wang Y, Zhang C, et al. Chemical recycling of carbon fiber reinforced epoxy resin composites via selective cleavage of the carbon-nitrogen bond. ACS Sustain Chem Eng. 2015;3:3332.

    CAS  Article  Google Scholar 

  16. Deng T, Liu Y, Cui X, Yang Y, Jia S, Wang Y, et al. Cleavage of C-N bonds in carbon fiber/epoxy resin composites. Green Chem. 2015;17:2141.

    CAS  Article  Google Scholar 

  17. Hashimoto T, Meiji H, Urushisaki M, Sakaguchi T, Kawabe K, Tsuchida C, et al. Degradable and chemically recyclable epoxy resins containing acetal linkages: synthesis, properties, and application for carbon fiber-reinforced plastics. J Polym Sci Part A Polym Chem. 2012;50:3674.

    CAS  Article  Google Scholar 

  18. Yamaguchi A, Hashimoto T, Kakichi Y, Urushisaki M, Sakaguchi T, Kawabe K, et al. Recyclable carbon fiber-reinforced plastics (CFRP) containing degradable acetal linkages: synthesis, properties, and chemical recycling. J Polym Sci Part A Polym Chem. 2015;53:1052.

    CAS  Article  Google Scholar 

  19. Yamaguchi A, Hashimoto T, Kakichi Y, Urushisaki M, Sakaguchi T, Kawabe K, et al. Recyclable, adhesive, acetal-linkage-containing epoxy resins: measuring the adhesive properties with carbon fibers. Kobunshi Ronbunshu. 2016;73:244.

    CAS  Article  Google Scholar 

  20. Kakichi K, Hashimoto T, Yamaguchi A, Urushisaki M, Sakaguchi T, Kawabe K, et al. Development of acetal linkage-containing matrix epoxy resins with high toughness and degradability for chemically recyclable CFRP. Kobunshi Ronbunshu. 2017;74:208.

    CAS  Article  Google Scholar 

  21. Kakichi K, Yamaguchi A, Hashimoto T, Urushisaki M, Sakaguchi T, Kawabe K, et al. Development of recyclable carbon fiber-reinforced plastics (CFRPs) with controlled degradability and stability using acetal linkage-containing epoxy resins. Polym J. 2017;49:851.

    CAS  Article  Google Scholar 

  22. Kawabe K. New spreading technology for carbon fiber tow and its application to composite materials. Sen’i Gakkaishi. 2008;64:262.

    Google Scholar 

Download references

Acknowledgements

We are grateful to Nicca Chemical Co., Ltd., Fukui, Japan for allowing us to use its sizing agent-applying apparatus. We also thank Nippon Carbide Industries, Tokyo, Japan for donating 2-hydroxyethyl vinyl ether and diethylene glycol monovinyl ether.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Tamotsu Hashimoto.

Ethics declarations

Conflict of interest

The authors declare that they have no conflict of interest.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Aoki, R., Yamaguchi, A., Hashimoto, T. et al. Preparation of carbon fibers coated with epoxy sizing agents containing degradable acetal linkages and synthesis of carbon fiber-reinforced plastics (CFRPs) for chemical recycling. Polym J 51, 909–920 (2019). https://doi.org/10.1038/s41428-019-0202-7

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41428-019-0202-7

Further reading

Search

Quick links