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Value-added Utilization of Lignin Residue from Pretreatment Process of Lignocellulosic Biomass

목질계 바이오매스 전처리 공정에서 발생하는 리그닌 부산물 활용 기술 개발 동향

  • Jung, Jae Yeong (Department of chemical engineering, Kyung Hee University) ;
  • Lee, Yumi (Department of chemical engineering, Kyung Hee University) ;
  • Lee, Eun Yeol (Department of chemical engineering, Kyung Hee University)
  • 정재영 (경희대학교 공과대학 화학공학과) ;
  • 이유미 (경희대학교 공과대학 화학공학과) ;
  • 이은열 (경희대학교 공과대학 화학공학과)
  • Received : 2016.02.17
  • Accepted : 2016.03.18
  • Published : 2016.04.10

Abstract

Due to the high price volatility and environmental concern of petroleum, biofuels such as bioethanol produced from lignocellulosic biomass have attracted much attention. It is also expected that the amount of lignin residue generated from pretreatment of lignocellulosic biomass will increase as the volume of cellulosic bioethanol increases. Lignin is a natural aromatic polymer and has very complex chemical structures with chemical functional groups. Chemical modification of lignin such as oxypropylation and epoxidation has also been applied to the production of value-added bioplastics such as polyurethane and polyester with enhanced thermal and mechanical properties. In addition, lignin can be used for carbon fiber production in automobile industries. This review highlights recent progresses in utilizations and chemical modifications of lignin for the production of bioplastics, resins, and carbon fiber.

Acknowledgement

Supported by : 한국산업기술평가관리원(KEIT)

References

  1. H. J. Eom, Y. K. Hong, S. H. Chung, Y. M. Park, and K. Y. Lee, Depolymerization of Kraft Lignin at Water-Phenol Mixture Solvent in Near Critical Region, J. Energy Eng., 20, 36-43 (2011). https://doi.org/10.5855/ENERGY.2011.20.1.036
  2. J. A. Melero, J. Iglesias, and A. Garcia, Biomass as renewable feedstock in standard refinery units. Feasibility, opportunities and challenges, Energy Environ. Sci., 5, 7393-7420 (2012). https://doi.org/10.1039/c2ee21231e
  3. J. Y. Zhu and X. J. Pan, Woody biomass pretreatment for cellulosic ethanol production: technology and energy consumption evaluation, Bioresour. Technol., 101, 4992-5002 (2010). https://doi.org/10.1016/j.biortech.2009.11.007
  4. M. Ballesteros, J. M. Oliva, M. J. Negro, P. Manzanares, and I. Ballesteros, Ethanol from lignocellulosic materials by a simultaneous saccharification and fermentation process (SFS) with Kluyveromycesmarxianus CECT 10875, Process Biochem., 39, 1843-1848 (2004). https://doi.org/10.1016/j.procbio.2003.09.011
  5. Z. P. Lei, Z. Q. Hu, H. F. Shui, S. B. Ren, Z. C. Wang, S. G. Kang, and C. X. Pan, Pyrolysis of lignin following ionic liquid pretreatment at low temperature, Fuel Process. Technol., 138, 612-615 (2015). https://doi.org/10.1016/j.fuproc.2015.06.049
  6. S. Kubo and J. F. Kadla, Lignin-based carbon fibers: Effect of synthetic polymer blending on fiber properties, J. Polym. Environ., 13, 97-105 (2005). https://doi.org/10.1007/s10924-005-2941-0
  7. M. Kleinert and T. Barth, Phenols from lignin, Chem. Eng. Technol., 31, 736-745 (2008). https://doi.org/10.1002/ceat.200800073
  8. X. Luo, A. Mohanty, and M. Misra, Lignin as a reactive reinforcing filler for water-blown rigid biofoam composites from soy oil-based polyurethane, Ind. Crop. Prod., 47, 13-19 (2013). https://doi.org/10.1016/j.indcrop.2013.01.040
  9. S. Sen, S. Patil, and D. S. Argyropoulos, Thermal properties of lignin in copolymers, blends, and composites: a review, Green Chem., 17, 4862-4887 (2015). https://doi.org/10.1039/C5GC01066G
  10. E. Dorrestijn, L. J. Laarhoven, I. W. Arends, and P. Mulder, The occurrence and reactivity of phenoxyl linkages in lignin and low rank coal, J. Anal. Appl. Pyrolysis, 54, 153-192 (2000). https://doi.org/10.1016/S0165-2370(99)00082-0
  11. A. K. Sangha, J. M. Parks, R. F. Standaert, A. Ziebell, M. Davis, and J. C. Smith, Radical coupling reactions in lignin synthesis: a density functional theory study, J. Phys. Chem. B, 116, 4760-4768 (2012).
  12. F. S. Chakar and A. J. Ragauskas, Review of current and future softwood kraft lignin process chemistry, Ind. Crop. Prod., 20, 131-141 (2004). https://doi.org/10.1016/j.indcrop.2004.04.016
  13. P. Azadi, O. R. Inderwildi, R. Farnood, and D. A. King, Liquid fuels, hydrogen and chemicals from lignin: a critical review, Renew. Sust. Energ. Rev., 21, 506-523 (2013). https://doi.org/10.1016/j.rser.2012.12.022
  14. S. Laurichesse and L. Averous, Chemical modification of lignins: towards biobased polymers, Prog. Polym. Sci., 39, 1266-1290 (2014). https://doi.org/10.1016/j.progpolymsci.2013.11.004
  15. A. Lee and Y. Deng, Green polyurethane from lignin and soybean oil through non-isocyanate reactions Eur. Polym. J., 63, 67-73 (2015). https://doi.org/10.1016/j.eurpolymj.2014.11.023
  16. Y. Park, W. O. Doherty, and P. J. Halley, Developing lignin-based resin coatings and composites, Ind. Crop. Prod., 27, 163-167 (2008). https://doi.org/10.1016/j.indcrop.2007.07.021
  17. B. Zhao, G. Chen, Y. Liu, K. Hu, and R. Wu, Synthesis of lignin base epoxy resin and its characterization, J. Mater. Sci. Lett., 20, 859-862 (2001). https://doi.org/10.1023/A:1010975132530
  18. Y. J. Jo, S. H. Choi, and E. Y. Lee, Production of Biopolyols, Bioisocyanates and Biopolyurethanes from Renewable Biomass, Appl. Chem. Eng., 24, 579-586 (2013). https://doi.org/10.14478/ace.2013.1081
  19. H. Hatakeyema, N. Tanamachi, H. Matsumura, S. Hirose, and T. Hatakeyama, Bio-based polyurethane composite foams with inorganic fillers studied by thermogravimetry, Thermochim. Acta, 431, 155-160 (2005). https://doi.org/10.1016/j.tca.2005.01.065
  20. R. Auvergne, S. Caillol, G. David, B. Boutevin, and J. P. Pascault, Biobased thermosetting epoxy: present and future, Chem. Rev., 114, 1082-1115 (2013).
  21. L. Pilato, Phenolic resins: 100Years and still going strong, React. Funct. Polym., 73, 270-277 (2013). https://doi.org/10.1016/j.reactfunctpolym.2012.07.008
  22. K. H. Kim, Y. J. Jo, C. G. Lee, and E. Y. Lee, Solvothermal liquefaction of microalgalTetraselmis sp. biomass to prepare biopolyols by using PEG# 400-blended glycerol, Algal Res., 12, 539-544 (2015). https://doi.org/10.1016/j.algal.2015.08.007
  23. K. Nakamura, T. Hatakeyama, and H. Hatakeyama, Thermal properties of solvolysis lignin-derived polyurethanes, Polym. Adv. Technol., 3, 151-155 (1992). https://doi.org/10.1002/pat.1992.220030402
  24. S. Hu, C. Wan, and Y. Li, Production and characterization of biopolyols and polyurethane foams from crude glycerol based liquefaction of soybean straw, Bioresour. Technol., 103, 227-233 (2012). https://doi.org/10.1016/j.biortech.2011.09.125
  25. Y. Li and A. J. Ragauskas, Kraft lignin-based rigid polyurethane foam, J. Wood Chem. Technol., 32, 210-224 (2012). https://doi.org/10.1080/02773813.2011.652795
  26. N. Mahmood, Z. Yuan, J. Schmidt, and C. C. Xu, Production of polyols via direct hydrolysis of kraft lignin: Effect of process parameters, Bioresour. Technol., 139, 13-20 (2013). https://doi.org/10.1016/j.biortech.2013.03.199
  27. S. Hu, X. Luo, and Y. Li, Polyols and polyurethanes from the liquefaction of lignocellulosic biomass, Chem. Sus. Chem., 7, 66-72 (2014). https://doi.org/10.1002/cssc.201300760
  28. E. B. da Silva, M. Zabkova, J. D. Araujo, C. A. Cateto, M. F. Barreiro, M. N. Belgacem, and A. E. Rodrigues, An integrated process to produce vanillin and lignin-based polyurethanes from Kraft lignin, Chem. Eng. Res. Des., 87, 1276-1292 (2009). https://doi.org/10.1016/j.cherd.2009.05.008
  29. Y. Jin, X. Ruan, X. Cheng, and Q. Lu, Liquefaction of lignin by polyethyleneglycol and glycerol, Bioresour. Technol., 102, 3581-3583 (2011). https://doi.org/10.1016/j.biortech.2010.10.050
  30. H. Q. Li, Q. Shao, H. Luo, and J. Xu, Polyurethane foams from alkaline lignin-based polyether polyol, J. Appl. Polym. Sci., Doi:10.1002/app.43261. https://doi.org/10.1002/app.43261
  31. J. H. Lee, J. H. Lee, D. K. Kim, C. H. Park, J. H. Yu, and E. Y. Lee, Crude glycerol-mediated liquefaction of empty fruit bunches saccharification residues for preparation of biopolyurethane, J. Ind. Eng. Chem., 34, 157-164 (2016). https://doi.org/10.1016/j.jiec.2015.11.007
  32. J. C. Dominguez, M. Oliet, M. V. Alonso, E. Rojo, and F. Rodriguez, Structural, thermal and rheological behavior of a bio-based phenolic resin in relation to a commercial resol resin, Ind. Crop. Prod., 42, 308-314 (2013). https://doi.org/10.1016/j.indcrop.2012.06.004
  33. J. M. Perez, M. Oliet, M. V. Alonso, and F. Rodriguez, Cure kinetics of lignin-novolac resins studied by isoconversional methods, Thermochim. Acta, 487, 39-42 (2009). https://doi.org/10.1016/j.tca.2009.01.005
  34. S. Cheng, Z. Yuan, M. Leitch, M. Anderson, and C. C. Xu, Highly efficient de-polymerization of organosolv lignin using a catalytic hydrothermal process and production of phenolic resins/adhesives with the depolymerized lignin as a substitute for phenol at a high substitution ratio, Ind. Crop. Prod., 44, 315-322 (2013). https://doi.org/10.1016/j.indcrop.2012.10.033
  35. N. S. Cetin and N. Ozmen, Use of organosolv lignin in phenol-formaldehyde resins for particleboard production: I. Organosolv lignin modified resins, Int. J. Adhes. Adhes., 22, 477-480 (2002). https://doi.org/10.1016/S0143-7496(02)00058-1
  36. M. V. Alonso, M. Oliet, J. M. Perez, F. Rodriguez, and J. Echeverria, Determination of curing kinetic parameters of lignin-phenol-formaldehyde resol resins by several dynamic differential scanning calorimetry methods, Thermochim. Acta, 419, 161-167 (2004). https://doi.org/10.1016/j.tca.2004.02.004
  37. C. C. Lin and H. Teng, Influence of the formaldehyde-to-phenol ratio in resin synthesis on the production of activated carbons from phenol-formaldehyde resins, Ind. Eng. Chem. Res., 41, 1986-1992 (2002). https://doi.org/10.1021/ie010610n
  38. P. K. Pal, A. Kumar, and S. K. Gupta, Modelling of resole type phenol formaldehyde polymerization, Polymer, 22, 1699-1704 (1981). https://doi.org/10.1016/0032-3861(81)90389-X
  39. W. J. Lee, K. C. Chang, and I. M. Tseng, Properties of phenol formaldehyde resins prepared from phenol-liquefied lignin, J. Appl. Polym. Sci., 124, 4782-4788 (2012).
  40. W. Zhang, Y. Ma, Y. Xu, C. Wang, and F. Chu, Lignocellulosic ethanol residue-based lignin-phenol-formaldehyde resin adhesive, Int. J. Adhes. Adhes., 40, 11-18 (2013). https://doi.org/10.1016/j.ijadhadh.2012.08.004
  41. W. J. Lee and Y. C. Chen, Novolak PF resins prepared from phenol liquefied Cryptomeria japonica and used in manufacturing moldings, Bioresour. Technol., 99, 7247-7254 (2008). https://doi.org/10.1016/j.biortech.2007.12.060
  42. J. M. Raquez, M. Deleglise, M. F. Lacrampe, and P. Krawczak, Thermosetting (bio) materials derived from renewable resources: a critical review, Prog. Polym. Sci., 35, 487-509 (2010). https://doi.org/10.1016/j.progpolymsci.2010.01.001
  43. B. J. Anderson, Thermal stability of high temperature epoxy adhesives by thermogravimetric and adhesive strength measurements, Polym. Degrad. Stabil., 96, 1874-1881 (2011). https://doi.org/10.1016/j.polymdegradstab.2011.07.010
  44. M. R. Bagherzadeh, A. Daneshvar, and H. Shariatpanahi, Novel water-based nanosiloxane epoxy coating for corrosion protection of carbon steel, Surf. Coat. Technol., 206, 2057-2063 (2012). https://doi.org/10.1016/j.surfcoat.2011.05.036
  45. T. I. Yang, C. W. Peng, Y. L. Lin, C. J. Weng, G. Edgington, A. Mylonakis, T. C. Huang, C. H. Hsu, J. M. Yeh, and Y. Wei, Synergistic effect of electroactivity and hydrophobicity on the anticorrosion property of room-temperature-cured epoxy coatings with multiscale structures mimicking the surface of Xanthosomasagittifolium leaf, J. Mater. Chem., 22, 15845-15852 (2012). https://doi.org/10.1039/c2jm32365f
  46. K. Li, K. Wang, M. S. Zhan, and W. Xu, The change of thermal-mechanical properties and chemical structure of ambient cured DGEBA/TEPA under accelerated thermo-oxidative aging, Polym. Degrad. Stabil., 98, 2340-2346 (2013). https://doi.org/10.1016/j.polymdegradstab.2013.08.014
  47. R. F. Fischer, Polyesters from epoxides and anhydrides, J. Polym. Sci., 44, 155-172 (1960). https://doi.org/10.1002/pol.1960.1204414314
  48. L. H. Sinh, N. N. Trung, B. T. Son, S. Shin, D. T. Thanh, and J. Y. Bae, Curing behavior, thermal, and mechanical properties of epoxy resins cured with a novel liquid crystalline dicarboxylic acid curing agent, Polym. Eng. Sci., 54, 695-703 (2014). https://doi.org/10.1002/pen.23585
  49. E. C. Dodds and W. Lawson, Synthetic estrogenic agents without the phenanthrene nucleus, Nature, 137, 996-996 (1936).
  50. K. L. Howdeshell, A. K. Hotchkiss, K. A. Thayer, J. G. Vandenbergh, and F. S. VomSaal, Environmental toxins: exposure to bisphenolA advances puberty, Nature, 401, 763-764 (1999). https://doi.org/10.1038/44517
  51. A. Campanella, M. A. Baltanas, M. C. Capel-Sanchez, J. M. Campos-Martin, and J. L. G. Fierro, Soybean oil epoxidation with hydrogen peroxide using an amorphous Ti/SiO 2 catalyst, Green Chem., 6, 330-334 (2004). https://doi.org/10.1039/B404975F
  52. T. Koike, Progress in development of epoxy resin systems based on wood biomass in Japan, Polym. Eng. Sci., 52, 701-717 (2012). https://doi.org/10.1002/pen.23119
  53. N. E. El Mansouri, Q. Yuan, and F. Huang, Synthesis and characterization of kraft lignin-based epoxy resins, Bioresources, 6, 2492-2503 (2011).
  54. T. Malutan, R. Nicu, and V. I. Popa, Lignin modification by epoxidation, Bioresources, 3, 1371-1376 (2008).
  55. P. Y. Kuo, M. Sain, and N. Yan, Synthesis and characterization of an extractive-based bio-epoxy resin from beetle infested Pinus contorta bark, Green Chem., 16, 3483-3493 (2014). https://doi.org/10.1039/c4gc00459k
  56. H. Pan, G. Sun, and T. Zhao, Synthesis and characterization of aminated lignin, Int. J. Biol. Macromol., 59, 221-226 (2013). https://doi.org/10.1016/j.ijbiomac.2013.04.049
  57. C. Sasaki, M. Wanaka, H. Takagi, S. Tamura, C. Asada, and Y. Nakamura, Evaluation of epoxy resins synthesized from steam-exploded bamboo lignin, Ind. Crop. Prod., 43, 757-761 (2013). https://doi.org/10.1016/j.indcrop.2012.08.018
  58. F. Ferdosian, Z. Yuan, M. Anderson, and C. C. Xu, Synthesis of lignin-based epoxy resins: optimization of reaction parameters using response surface methodology, RSC Adv., 4, 31745-31753 (2014). https://doi.org/10.1039/C4RA03978E
  59. F. Ferdosian, Z. Yuan, M. Anderson, and C. C. Xu, Sustainable lignin-based epoxy resins cured with aromatic and aliphatic amine curing agents: Curing kinetics and thermal properties, Thermochim. Acta, 618, 48-55 (2015). https://doi.org/10.1016/j.tca.2015.09.012
  60. J. Qin, M. Woloctt, and J. Zhang, Use of polycarboxylic acid derived from partially depolymerized lignin as a curing agent for epoxy application, ACS Sustain. Chem. Eng., 2, 188-193 (2013).
  61. T. Saito, R. H. Brown, M. A. Hunt, D. L. Pickel, J. M. Pickel, J. M. Messman, F. S. Baker, M. Keller, and A. K. Naskar, Turning renewable resources into value-added polymer: development of lignin-based thermoplastic, Green Chem., 14, 3295-3303 (2012). https://doi.org/10.1039/c2gc35933b
  62. A. L. Korich, K. M. Clarke, D. Wallace, and P. M. Iovine, Chemical modification of a lignin model polymer via arylboronate ester formation under mild reaction conditions, Macromolecules, 42, 5906-5908 (2009). https://doi.org/10.1021/ma901146b
  63. J. H. Lora and W. G. Glasser, Recent industrial applications of lignin: a sustainable alternative to nonrenewable materials, J. Polym. Environ., 10, 39-48 (2002). https://doi.org/10.1023/A:1021070006895
  64. M. Evtiouguina, A. Barros-Timmons, J. J. Cruz-Pinto, C. P. Neto, M. N. Belgacem, and A. Gandini, Oxypropylation of cork and the use of the ensuing polyols in polyurethane formulations, Biomacromolecules, 3, 57-62 (2002). https://doi.org/10.1021/bm010100c
  65. B. Ahvazi, O. Wojciechowicz, T. M. Ton-That, and J. Hawari, Preparation of lignopolyols from wheat straw soda lignin, J. Agric. Food Chem., 59, 10505-10516 (2011). https://doi.org/10.1021/jf202452m
  66. C. A. Cateto, M. F. Barreiro, A. E. Rodrigues, and M. N. Belgacem, Optimization study of lignin oxypropylation in view of the preparation of polyurethane rigid foams, Ind. Eng. Chem. Res., 48, 2583-2589 (2009). https://doi.org/10.1021/ie801251r
  67. H. Nadji, C. Bruzzese, M. N. Belgacem, A. Benaboura, and A. Gandini, Oxypropylation of lignins and preparation of rigid polyurethane foams from the ensuing polyols, Macromol. Mater. Eng., 290, 1009-1016 (2005). https://doi.org/10.1002/mame.200500200
  68. H. Sadeghifar, C. Cui, and D. S. Argyropoulos, Toward thermoplastic lignin polymers. Part 1. Selective masking of phenolic hydroxyl groups in kraftlignins via methylation and oxypropylation chemistries, Ind. Eng. Chem. Res., 51, 16713-16720 (2012). https://doi.org/10.1021/ie301848j
  69. M. Yoshioka, Y. Nishio, D. Saito, H. Ohashi, M. Hashimoto, and N. Shiraishi, Synthesis of biopolyols by mild oxypropylation of liquefied starch and its application to polyurethane rigid foams, J. Appl. Polym. Sci., 130, 622-630 (2013). https://doi.org/10.1002/app.39167
  70. M. V. Alonso, M. Oliet, F. Rodriguez, J. Garcia, M. A. Gilarranz, and J. J. Rodriguez, Modification of ammonium lignosulfonate by phenolation for use in phenolic resins, Bioresour. Technol., 96, 1013-1018 (2005). https://doi.org/10.1016/j.biortech.2004.09.009
  71. L. Hu, H. Pan, Y. Zhou, and M. Zhang, Methods to improve lignin's reactivity as a phenol substitute and as replacement for other phenolic compounds: A brief review, BioResources, 6, 3515-3525 (2011).
  72. J. Podschun, B. Saake, and R. Lehnen, Reactivity enhancement of organosolv lignin by phenolation for improved bio-based thermosets, Eur. Polym. J., 67, 1-11 (2015).
  73. R. Fang, X. Cheng, and W. S. Lin, Preparation and application of dimer acid/lignin graft copolymer, BioResources, 6, 2874-2884 (2011).
  74. J. Qiao, M. Guo, L. Wang, D. Liu, X. Zhang, L. Yu, W. Song and Y. Liu, Recent advances in polyolefin technology, Polym. Chem., 2, 1611-1623 (2011). https://doi.org/10.1039/c0py00352b
  75. H. Chung and N. R. Washburn, Chemistry of lignin-based materials, Green Mat., 1, 137-160 (2012).
  76. M. Mikulasova, B. Kosikova, P. Alexy, F. Kacik, and E. Urgelova, Effect of blending lignin biopolymer on the biodegradability of polyolefin plastics, World J. Microbiol. Biotechnol., 17, 601-607 (2001). https://doi.org/10.1023/A:1012415023385
  77. G. Cazacu, M. C. Pascu, L. Profire, A. I. Kowarski, M. Mihaes, and C. Vasile, Lignin role in a complex polyolefin blend, Ind. Crop. Prod., 20, 261-273 (2004). https://doi.org/10.1016/j.indcrop.2004.04.030
  78. M. Nahmany and A. Melman, Chemoselectivity in reactions of esterification, Org. Biomol. Chem., 2, 1563-1572 (2004). https://doi.org/10.1039/b403161j
  79. G. Sivasankarapillai, A. G. McDonald, and H. Li, Lignin valorization by forming toughened lignin-co-polymers: Development of hyperbranchedprepolymers for cross-linking, Biomass Bioenerg., 47, 99-108 (2012). https://doi.org/10.1016/j.biombioe.2012.09.057
  80. T. Saito, R. H. Brown, M. A. Hunt, D. L. Pickel, J. M. Pickel, J. M. Messman, F. S. Baker, M. Keller, and A. K. Naskar, Turning renewable resources into value-added polymer: development of lignin-based thermoplastic, Green Chem., 14, 3295-3303 (2012). https://doi.org/10.1039/c2gc35933b
  81. Z. X. Guo and A. Gandini, Polyesters from lignin-2. The copolyesterification of kraft lignin and polyethylene glycols with dicarboxylic acid chlorides, Eur. Polym. J., 27, 1177-1180 (1991). https://doi.org/10.1016/0014-3057(91)90053-Q
  82. N. T. ThanhBinh, N. D. Luong, D. O. Kim, S. H. Lee, B. J. Kim, Y. S. Lee, and J. D. Nam, Synthesis of lignin-based thermoplastic copolyester using kraft lignin as a macromonomer, Compos. Interfaces, 16, 923-935 (2009). https://doi.org/10.1163/092764409X12477479344485
  83. E. Frank, L. M. Steudle, D. Ingildeev, J. M. Sporl, and M. R. Buchmeiser, Carbon fibers: precursor systems, processing, structure, and properties, Angew. Chem. Int. Ed., 53, 5262-5298 (2014). https://doi.org/10.1002/anie.201306129
  84. I. Norberg, Y. Nordstrom, R. Drougge, G. Gellerstedt, and E. Sjoholm, A new method for stabilizing softwood kraft lignin fibers for carbon fiber production, J. Appl. Polym. Sci., 128, 3824-3830 (2013). https://doi.org/10.1002/app.38588
  85. J. F. Kadla, S. Kubo, R. A. Venditti, R. D. Gilbert, A. L. Compere, and W. Griffith, Lignin-based carbon fibers for composite fiber applications, Carbon, 40, 2913-2920 (2002). https://doi.org/10.1016/S0008-6223(02)00248-8
  86. D. A. Baker and T. G. Rials, Recent advances in low-cost carbon fiber manufacture from lignin, J. Appl. Polym. Sci., 130, 713-728 (2013). https://doi.org/10.1002/app.39273
  87. G. Gellerstedt, E. Sjoholm, and I. Brodin, The wood-based biorefinery: A source of carbon fiber?, Open Agric. J., 4, 119-124 (2010). https://doi.org/10.2174/1874331501004010119