Browsing by Author "Hummel, Michael"
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Item 2-Mercaptoimidazolium halides : structural diversity, stability and spontaneous racemisation(ROYAL SOC CHEMISTRY, 2020-09-28) Braun, Doris E.; Lampl, Martin; Kahlenberg, Volker; Wurst, Klaus; Schottenberger, Herwig; Hummel, Michael; Griesser, Ulrich J.; University of Innsbruck; Department of Bioproducts and BiosystemsExperimental and theoretical characterisation and studies of the stability of heterobicyclic thiazinium salts (bicyclic 2-mercaptoimidazolium chlorides and bromides) were performed to rationalise and understand the influence of the counterion (Cl−↔ Br−) and the replacement of CH by N on crystal packing, the influence of the anion on the moisture and temperature dependent stability, and the racemisation behaviour of the imidazo-thiazinium chloride. Six compounds were synthesised and for five of the compounds the structures were solved from single-crystal X-ray diffraction data. The structural features of the sixth compound could be derived from powder X-ray diffraction data comparisons. An exchange of the Cl−anion by Br−does not influence the crystal packing of the racemic thiazinium salt but increases its moisture dependent stability. In contrast, replacing the imidazole moiety of the cation by a triazole or tetrazole moiety results in distinct packing arrangements of the investigated bromide salts, although,substitution calculations suggest that isostructural packing arrangements might exist. The binary melting point phase diagram was constructed to confirm the nature of the racemic species of the thiazinium chloride, and differential scanning calorimetry and lattice energy minimisations were used to estimate the enthalpy difference between the racemic and enantiopure crystals, rationalising the high tendency of racemisation of the enantiopure compound.Item Accelerated thermostabilization through electron-beam irradiation for the preparation of cellulose-derived carbon fibers(Elsevier Ltd, 2024-01-31) Jang, Minjeong; Fliri, Lukas; Trogen, Mikaela; Choi, Dongcheon; Han, Jeong Heum; Kim, Jungwon; Kim, Sung Kon; Lee, Sungho; Kim, Sung Soo; Hummel, Michael; Department of Bioproducts and Biosystems; Biopolymer Chemistry and Engineering; Korea Institute of Science and Technology; Jeonbuk National UniversityThe potential of biobased materials like regenerated celluloses as precursors for carbon fibers (CFs) is long known. However, owing to an intrinsic two pathway pyrolysis mechanism of cellulose its carbonization is accompanied with side reactions under generation of volatiles. In practice, this leads to a reduced char yield, results in inferior mechanical properties of the CFs, and requires time-consuming thermostabilization procedures or wet-chemical pretreatments during production. Thus, their market share currently remains low. In ambitions to circumvent these issues, the potential of electron beam irradiation (EBI) as a dry chemical pretreatment for cellulosic CFs was investigated in this study. The conducted chemical analyses showed that high radiation dosages (2 MGy) lead to a strong depolymerization of the cellulose chains down to oligomers, while the fibrous macrostructure was preserved. Minor oxidation reactions were also evident. Thorough thermostabilization experiments under air in the temperature range from 100 °C to 250 °C revealed that reactions caused by EBI treatment alone were insufficient to increase the char yield. Only when the EBI treated precursor fibers are subjected to heating between 200 and 250 °C the char yield increased significantly to 34.4 % compared to 12.1 % for the untreated fiber. Furthermore, the EBI treatment strongly accelerated the reactions during thermostabilization allowing to collect CFs at heating rates of 2 °C/min compared to 0.5 °C/min needed for pristine fibers. Additionally, cellulose-lignin composite fibers were subjected to EBI treatment, proving that this strategy can also be applied to these emerging biobased CF precursors.Item Activation of carbon tow electrodes for use in iron aqueous redox systems for electrochemical applications(ROYAL SOC CHEMISTRY, 2020-06-21) Schröder, Philipp; Aguiló-Aguayo, Noemí; Auer, Andrea; Grießer, Christoph; Kunze-Liebhaüser, Julia; Ma, Yibo; Hummel, Michael; Obendorf, Dagmar; Bechtold, Thomas; University of Innsbruck; Innsbruck Medical University; Department of Bioproducts and Biosystems; Biopolymer Chemistry and EngineeringExcellent chemical inertness, good conductivity and high overpotentials for water electrolysis make carbon fibres (CFS) an ideal electrode material for electrochemical applications. A customized design of three-dimensional (3D) carbon electrodes can be achieved by tailored fibre placement of carbon tows with textile production techniques like embroidery. After manufacturing of the 3D structure, appropriate removal of the polymer coating and oxidative activation is required to achieve low overpotentials and avoid thermal treatments of the carbon structure. For the electrolytes Na[FeIII-racEDDHA] and K4[FeII(CN)6] a sequential treatment by acetone extraction and anodic oxidation was identified to yield optimum surface activation. Electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy of activated fibres indicated complete removal of the coating layer without damage of the CFS. From electrochemical impedance spectroscopy (EIS) at the carbon tow electrodes, charge transfer resistances of <0.1 Ω (0.023 Ω g) and < 0.2 Ω (0.046 Ω g) were determined at 50% state-of-charge (SoC) for 65 mM K4[FeII(CN)6] and 65 mM Na[FeIII-racEDDHA], respectively. In potentiostatic bulk electrolysis no electrode deactivation was observed during 10 charge/discharge cycles (5-6 hours) between 10% and 90% SoC. The processing of carbon tows by textile techniques to near net shaped 3D electrodes opens a new method to manufacture electrodes for electrochemical applications, such as redox flow cells.Item Air gap spinning of a cellulose solution in [DBNH][OAc] ionic liquid with a novel vertically arranged spinning bath to simulate a closed loop operation in the Ioncell® process(WILEY-BLACKWELL, 2021-02-05) Guizani, Chamseddine; Larkiala, Sauli; Moriam, Kaniz; Sawada, Daisuke; Elsayed, Sherif; Rantasalo, Sami; Hummel, Michael; Sixta, Herbert; Department of Bioproducts and Biosystems; BiorefineriesA novel, small-volume vertically arranged spin bath was successfully developed for an air gap lyocell-type spinning process. A maximum regeneration bath length with a minimum free volume characterizes the concept of the new spin bath. Using the ionic liquid (IL) 1,5-diazabicyclo[4.3.0]non-5-enium acetate [DBNH][OAc], the spin bath showed very good spinning performances of IL-cellulose dopes at high draw ratios and spinning duration for single filament spinning experiments. Using this new device, it was possible to get a step further in the optimization of the Ioncell® process and simulate a process closed loop operation by performing single filament spinning in IL/H2O mixtures. Good dope spinnability and preserved fibers mechanical properties were achieved in a coagulation bath containing up to 30 wt% IL. It is only at 45 wt% of IL in the bath that the spinnability and fibers mechanical properties started to deteriorate. The fibers fibrillar structure was less pronounced in IL-containing spinning bath in comparison to a pure water bath. However, their crystallinity after washing was preserved regardless of the spinning bath composition. The results presented in this work have a high relevance to the upscaling of emerging IL-based cellulose dissolution and spinning processes.Item Assessing Wood Supply Availability for Wood Construction in Finland(2022-12-16) Ostapenko, Michael; Hughes, Mark; Kemiantekniikan korkeakoulu; Hummel, MichaelItem Atomic layer deposition for pulmonary pharmaceuticals(2022-09-14) Pärkinen, Jenni; Miikkulainen, Ville; Kemiantekniikan korkeakoulu; Hummel, MichaelItem Binary Classification of Histopathological Images by Pre-Trained modified VGG16 model(2022-04-15) Lamoureux, Maxim; Jung, Alexander; Kemiantekniikan korkeakoulu; Hummel, MichaelItem Binary mixtures of ionic liquids-DMSO as solvents for the dissolution and derivatization of cellulose(ELSEVIER SCI LTD, 2019-05-15) Ferreira, Daniela C.; Oliveira, Mayara L.; Bioni, Thais A.; Nawaz, Haq; King, Alistair W.T.; Kilpeläinen, Ilkka; Hummel, Michael; Sixta, Herbert; El Seoud, Omar A.; Universidade de São Paulo; University of Helsinki; Biopolymer Chemistry and Engineering; Department of Bioproducts and BiosystemsThe efficiency of mixtures of ionic liquids (ILs) and molecular solvents in cellulose dissolution and derivatization depends on the structures of both components. We investigated the ILs 1-(1-butyl)-3-methylimidazolium acetate (C 4 MeImAc) and 1-(2-methoxyethyl)-3-methylimidazolium acetate (C 3 OMeImAc) and their solutions in dimethyl sulfoxide, DMSO, to assess the effect of presence of an ether linkage in the IL side-chain. Surprisingly, C 4 MeImAc-DMSO was more efficient than C 3 OMeImAc-DMSO for the dissolution and acylation of cellulose. We investigated bothsolvents using rheology, NMR spectroscopy, and solvatochromism. Mixtures of C 3 OMeImAc-DMSO are more viscous, less basic, and form weaker hydrogen bonds with cellobiose than C 4 MeImAc-DMSO. We attribute the lower efficiency of C 3 OMeImAc to “deactivation” of the ether oxygen and C2–H of the imidazolium ring due to intramolecular hydrogen bonding. Using the corresponding ILs with C2–CH 3 instead of C2–H, namely, 1-butyl-2,3-dimethylimidazolium acetate (C 4 Me 2 ImAc) and 1-(2-methoxyethyl)-2,3-dimethylimidazolium acetate (C 3 OMe 2 ImAc) increased the concentration of dissolved cellulose; without noticeable effect on biopolymer reactivity.Item Bio-based materials for solar cells(John Wiley & Sons, 2024-01-01) Miettunen, Kati; Hadadian, Mahboubeh; García, Joaquín Valdez; Lawrynowicz, Alicja; Akulenko, Elena; Rojas, Orlando J.; Hummel, Michael; Vapaavuori, Jaana; Department of Bioproducts and Biosystems; Department of Chemistry and Materials Science; Biopolymer Chemistry and Engineering; Multifunctional Materials Design; University of Turku; University of British ColumbiaPlant-based materials are emerging as an alternative to conventional components in advanced energy applications. Among these, energy harvesting from sunlight is highly attractive and, in fact, represents the fastest growing energy technology. This review addresses the broad field of solar cell science since plant-based components can be utilized in almost all solar technologies, and in certain photovoltaic technologies, they can fulfill most of the roles in photovoltaic devices. There is strengthened recent interest in developing sustainable materials options as well as new functionalities being developed for bio-based materials. This contribution describes the different options for plant-derived materials in photovoltaics and discusses their deployment feasibility. We focus on performance, lifetime, and embedded energy, all of which are critical to achieve—economically and sustainably–competitive photovoltaic devices. We address the tendency in the current literature for greenwashing, given that not all plant-based solutions are environmentally-sound at the device level. On the other hand, plant-based materials can offer functionalities that cannot be reached with currently used materials. This article is categorized under: Sustainable Energy > Solar Energy Emerging Technologies > Materials Sustainable Energy > Bioenergy.Item Birch bark – a valuable raw material; Pre-feasibility study for producing value-added products from birch bark(2023-09-07) Andersin, Astrid; Oinas, Pekka; Perustieteiden korkeakoulu; Hummel, MichaelItem Carbon Fibers Based on Cellulose–Lignin Hybrid Filaments: Role of Dehydration Catalyst, Temperature, and Tension during Continuous Stabilization and Carbonization(MDPI AG, 2024-07) Unterweger, Christoph; Schlapp-Hackl, Inge; Fürst, Christian; Robertson, Daria; Cho, MiJung; Hummel, Michael; Department of Bioproducts and Biosystems; Biopolymer Chemistry and Engineering; Wood K plusLignocellulose has served as precursor material for carbon fibers (CFs) before fossil-based polymers were discovered as superior feedstock. To date, CFs made from polyacrylonitrile have dominated the market. In search of low-cost carbon fibers for applications with medium strength requirements, cellulose and lignin, either as individual macromolecule or in combination, have re-gained interest as renewable raw material. In this study, cellulose with 30 wt% lignin was dry-jet wet-spun into a precursor filament for bio-based carbon fibers. The stabilization and carbonization conditions were first tested offline, using stationary ovens. Diammonium sulfate (DAS) and diammonium hydrogen phosphate were tested as catalysts to enhance the stabilization process. Stabilization is critical as the filaments’ strength properties drop in this phase before they rise again at higher temperatures. DAS was identified as a better option and used for subsequent trials on a continuous carbonization line. Carbon fibers with ca. 700 MPa tensile strength and 60–70 GPa tensile modulus were obtained at 1500 °C. Upon further carbonization at 1950 °C, moduli of >100 GPa were achieved.Item Cellulose-lignin composite fibres as precursors for carbon fibres. Part 1 – Manufacturing and properties of precursor fibres(ELSEVIER SCI LTD, 2020-09-28) Trogen, Mikaela; Le, Nguyen-Duc; Sawada, Daisuke; Guizani, Chamseddine; Vergara Lourencon, Tainise; Pitkänen, Leena; Sixta, Herbert; Shah, Riddhi; O'Neill, Hugh; Balakshin, Mikhail; Byrne, Nolene; Hummel, Michael; Biopolymer Chemistry and Engineering; Deakin University; Wood Material Science; Department of Bioproducts and Biosystems; Biorefineries; Oak Ridge National Laboratory; Lignin Chemistry; Department of Bioproducts and BiosystemsCellulose-lignin composite fibres were spun from ionic liquid (IL) solutions by dry-jet wet spinning. Birch pre-hydrolysed Kraft (PHK) pulp and organosolv beech (BL) or spruce lignin (SL) were dissolved in the IL 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH]OAc) to prepare spinning dopes. Fibres with lignin concentrations of up to 50% were spun successfully. The fibres were analysed focusing on important properties for the production of carbon fibres (CF). Due to the higher molar mass of the SL compared to the BL, SL showed higher stability in the spinning process, giving higher lignin content in the final fibres. The CF yield after carbonization increased with increasing lignin content. The higher carbon content of SL compared to BL, resulted in moderately higher CF yield of the SL fibres, compared to fibres with BL. Overall, the produced cellulose-lignin composite fibres show great potential as precursors for CF production.Item Cellulose-lignin composite fibres as precursors for carbon fibres. Part 1 – Manufacturing and properties of precursor fibres(ELSEVIER SCI LTD, 2021-01-15) Trogen, Mikaela; Le, Nguyen Duc; Sawada, Daisuke; Guizani, Chamseddine; Lourençon, Tainise Vergara; Pitkänen, Leena; Sixta, Herbert; Shah, Riddhi; O'Neill, Hugh; Balakshin, Mikhail; Byrne, Nolene; Hummel, Michael; Department of Bioproducts and Biosystems; Biopolymer Chemistry and Engineering; Wood Material Science; Biorefineries; Lignin Chemistry; Deakin University; Oak Ridge National LaboratoryCellulose-lignin composite fibres were spun from ionic liquid (IL) solutions by dry-jet wet spinning. Birch pre-hydrolysed Kraft (PHK) pulp and organosolv beech (BL) or spruce lignin (SL) were dissolved in the IL 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH]OAc) to prepare spinning dopes. Fibres with lignin concentrations of up to 50 % were spun successfully. The fibres were analysed focusing on important properties for the production of carbon fibres (CF). Due to the higher molar mass of the SL compared to the BL, SL showed higher stability in the spinning process, giving higher lignin content in the final fibres. The CF yield after carbonization increased with increasing lignin content. The higher carbon content of SL compared to BL, resulted in moderately higher CF yield of the SL fibres, compared to fibres with BL. Overall, the produced cellulose-lignin composite fibres show great potential as precursors for CF production.Item Cellulose-lignin composite fibres as precursors for carbon fibres. Part 2 - The impact of precursor properties on carbon fibres(ELSEVIER SCI LTD, 2020-12-15) Le, Nguyen-Duc; Trogen, Mikaela; Ma, Yibo; Varley, Russell J.; Hummel, Michael; Byrne, Nolene; Department of Bioproducts and Biosystems; Biopolymer Chemistry and Engineering; Biorefineries; Deakin UniversityCarbon fibres, despite being responsible lightweight structures that improve sustainability through fuel efficiency and occupational safety, remain largely derived from fossil fuels. Alternative precursors such as cellulose and lignin (bio-derived and low cost) are rapidly gaining attention as replacements for polyacrylonitrile (PAN, an oil-based and costly precursor). This study uses a cellulose-lignin composite fibre, to elucidate the influence of precursor fabrication parameters (draw ratio and lignin content) on the efficiency of stabilisation and carbonisation, from the perspective of the chemical, morphological and mechanical changes. The degradation of cellulose chains was the primary contributor to the decrease in mechanical properties during stabilization, but is slowed by the incorporation of lignin. The skin-core phenomenon, a typical effect in PAN-based carbon fibres production, was also observed. Finally, the carbonization of incompletely stabilized fibres is shown to produce hollow carbon fibres, which have potential application in batteries or membranes.Item Characterisation of cellulose pulps isolated from Miscanthus using a low-cost acidic ionic liquid(SPRINGER, 2020-05-01) Tu, Wei Chien; Weigand, Lisa; Hummel, Michael; Sixta, Herbert; Brandt-Talbot, Agnieszka; Hallett, Jason P.; Department of Bioproducts and Biosystems; Biopolymer Chemistry and Engineering; Biorefineries; Imperial College LondonThe ionoSolv pretreatment generates a cellulose pulp by extracting hemicellulose and lignin using low-cost ionic liquids. In this study, cellulose pulp was obtained from Miscanthus × giganteus using the protic ionic liquid triethylammonium hydrogen sulfate [N2220][HSO4] with 20% water as a co-solvent and characterised in detail for its material properties as a function of pretreatment severity. We measured the particle size distribution, porosity and crystallinity of the unbleached pulps and the molar weight distribution of the cellulose contained within. We report that the surface area increased and the size of the pulp particles decreased as ionoSolv processing progressed. While the native cellulose I structure was maintained, the average degree of polymerisation of the cellulose was reduced to a DPn of around 300, showing the cellulose polymers are shortened. We correlate the pulp properties with enzymatic saccharification yields, concluding that enzymatic saccharification of the cellulose after ionoSolv pretreatment is mainly enhanced by removing hemicellulose and lignin. We also observed that overtreatment deteriorated saccharification yield and that this coincides with cellulose fibrils becoming coated with pseudolignin redeposited from the ionic liquid solution, as demonstrated by FT-IR spectroscopy. Pseudolignin deposition increases the apparent lignin content, which is likely to increase chemical demand in bleaching, suggesting that both glucose release and material use benefit from a minimum lignin content. Overall, this study demonstrates that cellulose pulps isolated with ionoSolv processing are not only a promising intermediate for high-yield release of purified glucose for biorefining, but also have attractive properties for materials applications that require cellulose I fibrils. Graphic abstract: [Figure not available: see fulltext.].Item Chemical recycling of polycotton textiles: Fractionation of cotton by TEMPO-mediated oxidation(2024-01-23) Vuorinen, Julia; Periyasamy, Aravin; Kemian tekniikan korkeakoulu; Hummel, MichaelDeveloping chemical recycling methods for textiles is needed to improve the sustainability of the textile industry and provide solutions for recycling textile blends. TEMPO oxidation is a little-studied method in the context of textile recycling, although it could enable the upcycling of cotton in the form of nanocellulose. Earlier literature shows that pure cotton textiles can be successfully recycled by the method. This study aimed to fill the gap in the literature by testing if TEMPO oxidation could also be used for separating the materials of polycotton textiles. This study examined the effects of temperature, pH, and reaction time on the recovery of cotton and polyester as separate fractions. The TEMPO-oxidized polycotton samples were disintegrated using a high-shear mixer. The results showed a significantly lower yield of nanocellulose-like cotton fraction compared to earlier literature. However, the oxidization at a high temperature and pH allowed a high recovery of polyester. The polyester was recovered in fibre form and its purity increased with the temperature, pH, and reaction time. The chemical structure and molecular weight of the recovered polyester were not significantly damaged by the oxidation. The findings suggest that TEMPO oxidation is an interesting method for recycling polycotton textiles. Further studies are needed to improve the efficiency of material separation and the recovery of cotton.Item Chemically Accelerated Stabilization of a Cellulose-Lignin Precursor as a Route to High Yield Carbon Fiber Production(AMERICAN CHEMICAL SOCIETY, 2022-03-14) Le, Nguyen-Duc; Trogen, Mikaela; Varley, Russell J.; Hummel, Michael; Byrne, Nolene; Department of Bioproducts and Biosystems; Biopolymer Chemistry and Engineering; Deakin UniversityThe production of carbon fiber from bio-based or renewable resources has gained considerable attention in recent years with much of the focus upon cellulose, lignin, and cellulose-lignin composite precursor fibers. A critical step in optimizing the manufacture of carbon fiber is the stabilization process, through which the chemical and physical structure of the precursor fiber is transformed, allowing it to withstand very high temperatures. In this work, thermogravimetric analysis (TGA) is used to explore and optimize stabilization by simulating different stabilization profiles. Using this approach, we explore the influence of atmosphere (nitrogen or air), cellulose-lignin composition, and alternative catalysts on the carbon yield, efficiency, and rate of stabilization. Carbon dioxide and water vapor released during stabilization are analyzed by Fourier transform infrared (FTIR) spectroscopy, providing further information about the stabilization mechanism and the accelerating effect of oxygen and increased char yield (carbon content), especially for lignin. A range of different catalysts are evaluated for their ability to enhance the char yield, and a phosphorus-based flame retardant (H3PO4) proved to be the most effective; in fact, a doubling of the char yield was observed.Item Chemically Activated Spruce Organosolv Lignin as a Carbocatalyst for Heterogeneous Oxidative Dehydrogenations in the Liquid Phase(American Chemical Society, 2023-09-01) Lenarda, Anna; Melchionna, Michele; Aikonen, Santeri; Montini, Tiziano; Fornasiero, Paolo; Hu, Tao; Hummel, Michael; Helaja, Juho; Department of Bioproducts and Biosystems; Biopolymer Chemistry and Engineering; University of Helsinki; University of Trieste; University of OuluActivated carbons obtained from organosolv lignin by chemical activation with KOH and oxidized with diluted HNO3 were studied as catalysts for aerobic oxidative dehydrogenation (ODH) reactions. The structure/activity relationship was investigated through multiple techniques revealing the crucial role of oxygen functionality distribution in promoting two mechanistically archetypical ODH probe reactions: (i) the tetrahydroquinoline (THQ) aromatization, which represents ODH triggered by hydride transfer, and (ii) the 2-phenyl indole homocoupling reaction, a model for single-electron transfer-promoted reactions. In particular, the catalytic activity, correlating with oxygen functionality distribution on the basis of X-ray photoelectron spectroscopy and temperature-programmed desorption analysis, was associated with the C═O surface functionalities, as confirmed by blocking experiments with 2,2,2-trifluoroethyl hydrazine. Kinetic profiling tools were employed to assess THQ ODH product inhibition effects on the overall yield of the process as well as the extent of stoichiometric activity of the carbocatalyst. The breadth of the developed catalysts’ applicability was explored through selected relevant ODH reactions.Item Climate impact, (Bio-)degradation and Recyclability of bioplastics(2024-04-22) Tanhua, Aino; Holl, Max Philipp; Kemiantekniikan korkeakoulu; Hummel, MichaelPlastics are currently utilised in almost every aspect of human life, which is mainly due to the physical properties and low manufacturing costs. However, fossil-based plastics are associated with many environmental problems, such as plastic pollution, and greenhouse gas emissions. Solutions for this problem are rapidly needed. Bioplastics have been proposed as a more environmentally friendly alternative to conventional plastics. Bioplastics are plastics that are either, biodegradable, derived from renewable resources or both. Bioplastics have clear advantages in environment aspects compared to conventional plastics such as decreased energy usage in production, less CO2 emissions and less durable microplastics in the environment. However, for bioplastics to be considered as a viable solution for problems caused by fossil-based plastics, several problems, such as high production costs, environmentally harmful resources, and inferior physical properties, still need to be solved. The aim of this bachelor’s thesis is to review how bioplastics compare to conventional plastics. This comparison has been studied especially from the perspectives of production, recycling, and climate impact. In addition, the current state of plastic pollution was studied to give an understanding on the importance of this study.Item Close Packing of Cellulose and Chitosan in Regenerated Cellulose Fibers Improves Carbon Yield and Structural Properties of Respective Carbon Fibers(AMERICAN CHEMICAL SOCIETY, 2020-10-12) Zahra, Hilda; Sawada, Daisuke; Guizani, Chamseddine; Ma, Yibo; Kumagai, Shogo; Yoshioka, Toshiaki; Sixta, Herbert; Hummel, Michael; Department of Bioproducts and Biosystems; Biopolymer Chemistry and Engineering; Biorefineries; Tohoku UniversityA low carbon yield is a major limitation for the use of cellulose-based filaments as carbon fiber precursors. The present study aims to investigate the use of an abundant biopolymer chitosan as a natural charring agent particularly on enhancing the carbon yield of the cellulose-derived carbon fiber. The ionic liquid 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH]OAc) was used for direct dissolution of cellulose and chitosan and to spin cellulose-chitosan composite fibers through a dry-jet wet spinning process (Ioncell). The homogenous distribution and tight packing of cellulose and chitosan revealed by X-ray scattering experiments enable a synergistic interaction between the two polymers during the pyrolysis reaction, resulting in a substantial increase of the carbon yield and preservation of mechanical properties of cellulose fiber compared to other cobiopolymers such as lignin and xylan.
