Cellulose-based carbon fibers prepared using electron-beam stabilization

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  • ABSTRACT

    Cellulose fibers were stabilized by treatment with an electron-beam (E-beam). The properties of the stabilized fibers were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The E-beam-stabilized cellulose fibers were carbonized in N2 gas at 800℃ for 1 h, and their carbonization yields were measured. The structure of the cellulose fibers was determined to have changed to hemicellulose and cross-linked cellulose as a result of the E-beam stabilization. The hemicellulose decreased the initial decomposition temperature, and the cross-linked bonds increased the carbonization yield of the cellulose fibers. Increasing the absorbed E-beam dose to 1500 kGy increased the carbonization yield of the cellulose-based carbon fiber by 27.5% upon exposure compared to untreated cellulose fibers.


  • KEYWORD

    electron-beam stabilization , carbonization yield , cellulose fiber , cross-linked bond

  • 1. Introduction

    Carbon fibers (CFs) have been used as reinforcements in aircraft, automobiles, boats, high-grade sporting goods, wind turbine blades, gas sensors and electromagnetic shielding due to their exceptionally good mechanical and electrical properties. As a result, demand for CFs has continuously increased, and research on new precursors to satisfy this demand is being conducted [1-3]. In general, the most exploited precursors for the preparation of CFs are pitch and synthetic polymers, but their application is limited due to energy and resource concerns [4-6]. Cellulose can be easily obtained from natural sources [7] and is a precursor to carbon fiber. Additionally, cellulose does not suffer from the energy and resource concerns associated with pitch and synthetic polymers [3]. However, the carbonization yield of cellulose-based carbon fiber does not exceed 10%–15% because of its very low initial carbon content (44.4%). Therefore, the cellulose-to-carbon-fiber yield needs to be as high as possible [8-10].

    The preparation process for CFs includes stabilization and carbonization steps. In general, the stabilization process uses thermal stabilization in an air atmosphere. During this process, the chemical structure of the precursor is changed through cyclization, oxidation, dehydrogenation, and cross-linking [11-13]. The modified chemical structure of the precursor affects the carbonization yield of the CFs. However, thermal stabilization is a time-consuming and complex process.

    Electron-beam (E-beam) treatment has been shown to induce polymer modification, such as cross-linking, curing, and grafting. The advantages of this method include a short reaction time and a simplified process compared to thermal stabilization [14-17]. In this study, cellulose fibers were treated using E-beam stabilization, which has a short reaction time and a simplified process, and CFs were prepared from these E-beam-stabilized cellulose fibers. The properties of the E-beam-stabilized cellulose fibers were investigated as a function of the absorbed E-beam dose.

    2. Experimental

       2.1. E-beam stabilization and carbonization of cellulose fibers

    In this work, the cellulose fiber was a lyocell fiber supplied by KOLON Industries (Korea). Twenty grams of cellulose fibers were treated by E-beam stabilization. During the E-beam stabilization, electrons were accelerated through a voltage gradient of 1.14 MeV, and the absorbed doses from the E-beam stabilization were between 500 and 2000 kGy. As shown in Table 1, the prepared samples were labeled according to the E-beam stabilization dosage conditions, as CeF, ECeF-500, ECeF-1000, ECeF-1500, and ECeF-2000. The E-beam-stabilized cellulose fibers were then carbonized in a nitrogen atmosphere at 800℃ for 1 h at a heating rate of 5℃/min.

       2.2. Analysis of E-beam-stabilized cellulose fibers

    fibers The surface morphology of the samples was observed using scanning electron microscopy (SEM; S-5500, Hitachi, Tokyo, Japan, KBSI) to investigate the effects of the E-beam stabilization on the cellulose fibers. The chemical structures of the samples were investigated using Fourier transform infrared spectroscopy (FT-IR; Bio-Rad Laboratories, Hercules, CA, USA) and X-ray photoelectron spectroscopy (XPS; ThermoVG Scientific, UK). The thermal properties of the samples were investigated using thermogravimetric analysis (TGA; Mettler-Toledo Inc., USA). The TGA scans were performed at 5℃/min under a constant nitrogen gas flow at temperatures ranging from 30℃ to 1000℃.

    3. Results and Discussion

       3.1. Surface properties of the cellulose fibers by E-beam stabilization

    The surface morphology of the E-beam-stabilized cellulose fibers and carbonized cellulose fibers was analyzed using SEM, as shown in Fig. 1. The surface morphologies of the cellulose fibers were unchanged by the E-beam stabilization. However, the cellulose fiber diameter was reduced by carbonization. The surface functional groups on the cellulose fibers exposed to the E-beam were investigated using FT-IR (Fig. 2). The FTIR spectrum shows peaks in the range 1200–500 cm–1 arising from cellulose fiber [18,19]. Pure cellulose fibers do not exhibit C=O (1740 cm–1) [15] or C=N (1628 cm–1) [4] peaks. However, these peaks did appear in the spectra for the E-beam-stabilized cellulose fibers. The oxygen and nitrogen functional groups in the cellulose fibers are modified by the oxygen and nitrogen in the air during the E-beam stabilization [20]. This modification is a result of the electrons created by the electron gun during the E-beam stabilization, forming oxygen and nitrogen radicals from the oxygen and nitrogen in the air. The functional groups of the cellulose fibers were modified by these oxygen and nitrogen radicals. Increases in the absorbed dose during the E-beam stabilization caused the intensity of the C=O, C=N, CH2 (2870 cm–1) and OH peaks (3150–3560 cm–1) in the cellulose fibers to increase.

       3.2. Chemical bond structures of the cellulose fibers by E-beam stabilization

    The structures of the surface chemical bonds in the E-beam-stabilized cellulose fibers were analyzed using XPS, and the elemental contents are shown in Table 2. The chemical compositions are also shown in Fig. 3 and Table 3. The surfaces of the E-beam-stabilized cellulose fibers consisted mostly of caron, oxygen and nitrogen. Increasing the absorbed E-beam dose caused the oxygen content to increase and the carbon content to decrease. In contrast to pure cellulose fibers, the E-beam-stabilized cellulose fibers contain an O-C=O bond (289.8 eV, ester bond) [21]. Increasing the absorbed E-beam dose was also found to increase the number of ester bonds in the cellulose fibers. The ECeF-1500 and ECeF-2000 samples exhibited the most ester bonds of the E-beam-stabilized cellulose fibers examined here. The ester bonds were created by reactions between the oxygen radicals and the cellulose fibers, and the ester bonds cross-linked the cellulose fibers, as presented in Fig. 4 [22]. However, the number of O-C-O bonds (288.3 eV) was decreased from 9.9% to 7.9% and the number of C-O bonds (286.7 eV) was increased from 14.3% to 22.5%, which increased with the increase in absorbed E-beam dose. The cellulose fibers transformed to a hemicellulose structure, which consists of short cellulose chains, due to the degradation of the O-C-O bond as a result of the E-beam stabilization (Fig. 5) [23-26].

       3.3. Thermal properties of the E-beam-stabilized cellulose fibers

    The thermal behavior of the E-beam-stabilized cellulose fibers was investigated by TGA, with the results shown in Fig. 6. The initial degradation temperature (IDT) decreased with an increase in the absorbed E-beam dose. In general, hemicellulose has a low IDT compared to cellulose [21,27]. The XPS results showed that the cellulose fibers were decomposed into hemicellulose by the E-beam stabilization. Therefore, increasing the absorbed E-beam dose decreased the IDT due to the increasing ratio of hemicellulose to cellulose fibers.

    At temperatures higher than the IDT, the samples exhibited a significant weight loss as the cellulose degraded. At temperatures over 400℃, all of the samples were carbonized, and the char yield of the cellulose fiber increased with the absorbed E-beam dose. From the XPS results, the cellulose fibers were found to be cross-linked by the E-beam stabilization. The crosslinked degree was increased by the increase in absorbed E-beam dose. In general, cross-linked bonds in polymers increase the degree of the char yield [28-30]. Therefore, the char yield of the cellulose fibers increased with the amount of cross-linked bonds in the cellulose fibers.

    The cellulose fibers and E-beam-stabilized cellulose fibers were carbonized in N2 gas at 800℃ for 1 h. The carbonization yield of the samples is shown Fig. 7. The carbonization yield of the non-treated cellulose fiber was 16%, and electron beam treated cellulose fiber was increased to 20.4%. In this study, the carbonization yield of the cellulose fiber was increased by 27.5% with a 1500 kGy absorbed E-beam dose or greater.

    4. Conclusions

    In this work, cellulose fibers were stabilized using an E-beam treatment, and their properties were analyzed with SEM, FT-IR, XPS, and TGA. The E-beam stabilization resulted in decomposition and cross-linking in the cellulose fibers, the degree of which increased with the increase in absorbed E-beam dose. The cellulose decomposed to hemicellulose, which exhibited a decreased IDT However, cross-linking was introduced via ester bonds in the cellulose fibers, which resulted in a 27.5% increase in the carbonization yield for the cellulose-based carbon fiber, compared to the pure cellulose fibers, when stabilized by a 1500 kGy absorbed E-beam dose.

  • 1. Kiadehi AD, Rahimpour A, Jahanshahi M, Ghoreyshi AA (2015) Novel carbon nano-fibers (CNF)/polysulfone (PSf) mixed matrix membranes for gas separation [J Ind Eng Chem] Vol.22 P.199 google doi
  • 2. Yim YJ, Rhee KY, Park SJ (2015) Influence of electroless nickel-plating on fracture toughness of pitch-based carbon fibre reinforced composites [Compos Part B: Eng] Vol.76 P.286 google doi
  • 3. Kuzmenko V, Naboka O, Gatenholm P, Enoksson P (2014) Ammonium chloride promoted synthesis of carbon nanofibers from electrospun cellulose acetate [Carbon] Vol.67 P.694 google doi
  • 4. Shin HK, Park M, Kang PH, Choi HS, Park SJ (2014) Preparation and characterization of polyacrylonitrile-based carbon fibers produced by electron beam irradiation pretreatment [J Ind Eng Chem] Vol.20 P.3789 google doi
  • 5. Guo Z, Liu Z, Ye L, Ge K, Zhao T (2015) The production of lignin-phenol-formaldehyde resin derived carbon fibers stabilized by BN preceramic polymer [Mater Lett] Vol.142 P.49 google doi
  • 6. Kim BJ, Eom Y, Kato O, Miyawaki J, Kim BC, Mochida I, Yoon SH (2014) Preparation of carbon fibers with excellent mechanical properties from isotropic pitches [Carbon] Vol.77 P.747 google doi
  • 7. Bettaieb F, Khiari R, Hassan ML, Belgacem MN, Bras J, Dufresne A, Mhenni MF (2015) Preparation and characterization of new cellulose nanocrystals from marine biomass Posidoniaoceanica [Ind Crops Prod] Vol.72 P.175 google doi
  • 8. Cho D, Kim JM, Kim D (2013) Phenolic resin infiltration and carbonization of cellulose-based bamboo fibers [Mater Lett] Vol.104 P.24 google doi
  • 9. Diakite M, Paul A, Jager C, Pielert J, Mumme J (2013) Chemical and morphological changes in hydrochars derived from microcrystalline cellulose and investigated by chromatographic, spectroscopic and adsorption techniques [Bioresour Technol] Vol.150 P.98 google doi
  • 10. Cagnon B, Py X, Guillot A, Stoeckli F, Chambat G (2009) Contributions of hemicellulose, cellulose and lignin to the mass and the porous properties of chars and steam activated carbons from various lignocellulosic precursors [Bioresour Technol] Vol.100 P.292 google doi
  • 11. Liu X, Zhu C, Guo J, Liu Q, Dong H, Gu Y, Liu R, Zhao N, Zhang Z, Xu J (2014) Nanoscale dynamic mechanical imaging of the skin-core difference: from PAN precursors to carbon fibers [Mater Lett] Vol.128 P.417 google doi
  • 12. Rahaman MSA, Ismail AF, Mustafa A (2007) A review of heat treatment on polyacrylonitrile fiber [Polym Degrad Stab] Vol.92 P.1421 google doi
  • 13. Mirbaha H, Arbab S, Zeinolebadi A, Nourpanah P (2013) An investigation on actuation behavior of polyacrylonitrile gel fibers as a function of microstructure and stabilization temperature [Smart Mater Struct] Vol.22 P.045019 google doi
  • 14. Driscoll M, Stipanovic A, Winter W, Cheng K, Manning M, Spiese J, Galloway RA, Cleland MR (2009) Electron beam irradiation of cellulose [Radiat Phys Chem] Vol.78 P.539 google doi
  • 15. Shin HK, Jeun JP, Kim HB, Kang PH (2012) Isolation of cellulose fibers from kenaf using electron beam [Radiat Phys Chem] Vol.81 P.936 google doi
  • 16. Wanichapichart P, Taweepreeda W, Nawae S, Choomgan P, Yasenchak D (2012) Chain scission and anti fungal effect of electron beam on cellulose membrane [Radiat Phys Chem] Vol.81 P.949 google doi
  • 17. Metreveli PK, Metreveli AK, Kholodkova EM, Ponomarev AV (2014) Effect of an electron beam on the subsequent pyrogenic distillation of lignin and cellulose [Radiat Phys Chem] Vol.96 P.167 google doi
  • 18. Reddy JP, Rhim JW (2014) Isolation and characterization of cellulose nanocrystals from garlic skin [Mater Lett] Vol.129 P.20 google doi
  • 19. Barud HGO, Barud HDS, Cavicchioli M, Amaral TSD, de Oliveira Junior OB, Santos DM, de Oliveira Almeida Petersen AL, Celes F, Borges VM, de Oliveira CI, de Oliveira PF, Furtado RA, Tavares DC, Ribeiro SJL (2015) Preparation and characterization of a bacterial cellulose/silk fibroin sponge scaffold for tissue regeneration [Carbohydr Polym] Vol.128 P.41 google doi
  • 20. Hakoda T, Zhang G, Hashimoto S (2001) Chain oxidation initiated by OH, O(3P) radicals, thermal electrons, and O3 in electron beam irradiation of 1,2-dichloroethylenes and air mixtures [Radiat Phys Chem] Vol.62 P.243 google doi
  • 21. Belgacem MN, Czeremuszkin G, Sapieha S, Gandini A (1995) Surface characterization of cellulose fibres by XPS and inverse gas chromatography [Cellulose] Vol.2 P.145 google doi
  • 22. Zhou Y, Stuart-Williams H, Farquhar GD, Hocart CH (2010) The use of natural abundance stable isotopic ratios to indicate the presence of oxygen-containing chemical linkages between cellulose and lignin in plant cell walls [Phytochemistry] Vol.71 P.982 google doi
  • 23. Ponomarev AV, Kholodkova EM, Metreveli AK, Metreveli PK, Erasov VS, Bludenko AV, Chulkov VN (2011) Phase distribution of products of radiation and post-radiation distillation of biopolymers: cellulose, lignin and chitin [Radiat Phys Chem] Vol.80 P.1186 google doi
  • 24. Waterhouse JS, Cheng S, Juchelka D, Loader NJ, McCarroll D, Switsur VR, Gautam L (2013) Position-specific measurement of oxygen isotope ratios in cellulose: isotopic exchange during heterotrophic cellulose synthesis [Geochim Cosmochim Acta] Vol.112 P.178 google doi
  • 25. Alberti A, Bertini S, Gastaldi G, Iannaccone N, Macciantelli D, Torri G, Vismara E (2005) Electron beam irradiated textile cellulose fibres: ESR studies and derivatisation with glycidyl methacrylate (GMA) [Eur Polym J] Vol.41 P.1787 google doi
  • 26. Sundar S, Bergey NS, Salamanca-Cardona L, Stipanovic A, Driscoll M (2014) Electron beam pretreatment of switchgrass to enhance enzymatic hydrolysis to produce sugars for biofuels [Carbohydr Polym] Vol.100 P.195 google doi
  • 27. Roman M, Winter WT (2004) Effect of sulfate groups from sulfuric acid hydrolysis on the thermal degradation behavior of bacterial cellulose [Biomacromolecules] Vol.5 P.1671 google doi
  • 28. Astrini N, Anah L, Haryono A (2012) Crosslinking parameter on the preparation of cellulose based hydrogel with divynilsulfone [Procedia Chem] Vol.4 P.275 google doi
  • 29. Rimdusit S, Jingjid S, Damrongsakkul S, Tiptipakorn S, Takeichi T (2008) Biodegradability and property characterizations of methyl cellulose: effect of nanocompositing and chemical crosslinking [Carbohydr Polym] Vol.72 P.444 google doi
  • 30. Yuan Z, Fan Q, Dai X, Zhao C, Lv A, Zhang J, Xu G, Qin M (2014) Crosslinkage effect of cellulose/laponite hybrids in aqueous dispersions and solid films [Carbohydr Polym] Vol.102 P.431 google doi
  • [Table 1.] The E-beam stabilization conditions of samples
    The E-beam stabilization conditions of samples
  • [Fig. 1.] Scanning electron microscopy image of cellulose fibers from CeF (a), ECeF-1500 (b) and ECeF-2000 (c) and carbon fibers from CeF (d), ECeF-1500 (e), and ECeF-2000 (f).
    Scanning electron microscopy image of cellulose fibers from CeF (a), ECeF-1500 (b) and ECeF-2000 (c) and carbon fibers from CeF (d), ECeF-1500 (e), and ECeF-2000 (f).
  • [Fig. 2.] Fourier transform infrared spectroscopy spectra of (a) CeF, (b) ECeF-500, (c) ECeF-1000, (d) ECeF-1500, and (e) ECeF-2000.
    Fourier transform infrared spectroscopy spectra of (a) CeF, (b) ECeF-500, (c) ECeF-1000, (d) ECeF-1500, and (e) ECeF-2000.
  • [Table 2.] XPS surface elemental analysis parameters of samples
    XPS surface elemental analysis parameters of samples
  • [Fig. 3.] C1s deconvolution of (a) CeF, (b) ECeF-500, (c) ECeF-1000, (d) ECeF-1500, and (e) ECeF-2000.
    C1s deconvolution of (a) CeF, (b) ECeF-500, (c) ECeF-1000, (d) ECeF-1500, and (e) ECeF-2000.
  • [Table 3.] C1s peak parameters of samples
    C1s peak parameters of samples
  • [Fig. 4.] Cross-linking mechanism of cellulose by electron-beam stabilization.
    Cross-linking mechanism of cellulose by electron-beam stabilization.
  • [Fig. 5.] Degradation mechanism of cellulose by electron-beam stabilization.
    Degradation mechanism of cellulose by electron-beam stabilization.
  • [Fig. 6.] Thermogravimetric analysis curves of samples at a heating rate of 5℃/min under nitrogen gas.
    Thermogravimetric analysis curves of samples at a heating rate of 5℃/min under nitrogen gas.
  • [Fig. 7.] Carbonization yield of cellulose based carbon fibers by electron-beam stabilization.
    Carbonization yield of cellulose based carbon fibers by electron-beam stabilization.