Strategies to enhance the carbon yield from cellulose-based precursor fiber through blending with other bio-based polymers as charring agents

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School of Chemical Technology | Doctoral thesis (article-based) | Defence date: 2024-10-30
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Date

2024

Department

Biotuotteiden ja biotekniikan laitos
Department of Bioproducts and Biosystems

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Mcode

Degree programme

Language

en

Pages

98 + app. 84

Series

Aalto University publication series DOCTORAL THESES, 228/2024

Abstract

The intrinsically low carbon yield upon cellulose pyrolysis is one major challenge in producing carbon fibers from cellulosic precursors. In this dissertation, chitosan and keratin, natural amino group−containing biopolymers, are utilized as natural charring agents to increase the yield of cellulose−based carbon fibers. Cellulose pulp was co−dissolved with chitosan or keratin in the ionic liquid 1,5-diazabicyclo[4.3.0]non-5-enium acetate, and then dry−jet wet spun via the so-called Ioncell® process. Thermogravimetric analysis showed that chitosan and keratin incorporation increased the char yield by >100 wt% and ~53 wt%, at ~21 wt% and ~30 wt% incorporation level, respectively. The role of chitosan and keratin as dehydration catalysts during cellulose pyrolysis up to 900 °C was confirmed through analysis of the volatile products. There was an enhanced production of water, CO2, and a reduced formation of levoglucosan. The change in the cellulose pyrolysis products was further seen in the increased production of several furanic compounds and acetic acid due to chitosan or keratin incorporation in the composite fibers. Mere physical contact between cellulose pulp and biopolymer powder did not alter the cellulose pyrolysis products, suggesting that close packing of the biopolymers in the composite fibers is needed for a synergistic interaction between cellulose and the additives during pyrolysis. Structural analyses revealed that chitosan was distributed homogeneously in the composite matrix. By contrast, keratin aggregates and open voids were found in the keratin composite fibers, leading to a suboptimum interaction between keratin and cellulose and, hence, a lower dehydration activity of keratin than chitosan. The same defects also led to a decrease in the mechanical properties of keratin-cellulose fibers. Chitosan and keratin introduced nitrogen to the composite- and resulting carbon fibers, respectively. The nitrogen might induce in-plane disorders in the aromatic carbon cluster, particularly at pyrolysis temperatures from 500 to 700 °C, but also promote the formation of crosslink structures due to the enhancement of the dehydration reaction. The cross-links increased the mechanical properties of carbon fibers derived from chitosan composite fibers, which can still be improved by further heat treatment such as higher carbonization temperatures. Open pores in the keratin composite fibers were also present in the resulting carbon fibers, resulting in fiber brittleness. However, nitrogen and open pores in carbon materials can be beneficial for electrochemical applications, with the possibility to tune them through tailored heat treatment protocols.

Description

Supervising professor

Hummel, Michael, Assoc. Prof., Aalto University, Department of Bioproducts and Biosystems, Finland

Thesis advisor

Sawada, Daisuke, Dr., Aalto University, Department of Bioproducts and Biosystems, Finland
Guizani, Chamseddine, Dr., Aalto University, Department of Bioproducts and Biosystems, Finland

Keywords

carbon, cellulose-based, biobased polymers

Other note

Parts

  • [Publication 1]: H. Zahra, D. Sawada, C. Guizani, Y. Ma, S. Kumagai, T. Yoshioka, H. Sixta, M. Hummel. 2020. Close Packing of Cellulose and Chitosan in Regenerated Cellulose Fibers Improves Carbon Yield and Structural Properties of Respective Carbon Fibers. Biomacromolecules 21(10), 4326–4335.
    Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202010306189
    DOI: 10.1021/acs.biomac.0c01117 View at publisher
  • [Publication 2]: H. Zahra, D. Sawada, S. Kumagai, Y. Ogawa, L.S. Johansson, Y. Ge, C. Guizani, T. Yoshioka, M. Hummel. 2021. Evolution of carbon nanostructure during pyrolysis of homogeneous chitosan-cellulose composite fibers. Carbon 158, 27-38.
    Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202110139612
    DOI: 10.1016/j.carbon.2021.08.062 View at publisher
  • [Publication 3]: H. Zahra, J. Selinger, D. Sawada, S. Kumagai, Y. Ogawa, H. Orelma, Y. Ma, S. Kumagai, T. Yoshioka, M. Hummel. 2022. Evaluation of keratin-cellulose composite fibers as precursor for carbon fibers. ACS Sustainable Chemistry & Engineering 10, 26, 8314–8325.
    Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202208245021
    DOI: 10.1021/acssuschemeng.2c00976 View at publisher

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https://urn.fi/URN:ISBN:978-952-64-2095-0

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[diss] Kemian tekniikan korkeakoulu / CHEM