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  • 1.
    de Carvalho, Danila Morais
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Moser, Carl
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Lindström, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Sevastyanova, Olena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Impact of the chemical composition of cellulosic materials on the nanofibrillation process and nanopaper properties2019In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 127, p. 203-211Article in journal (Refereed)
    Abstract [en]

    This paper investigated the impact of the amounts of lignin and hemicelluloses on cellulose nanofibers (CNFs). Birch and spruce wood were used to prepare holocellulose and cellulose samples by classical methods. To better assess the effect of the chemical composition on the CNF performance and simplify the process for CNF preparation, no surface derivatization method was applied for CNF preparation. Increased amounts of hemicelluloses, especially mannans, improved the defibration process, the stability of the CNFs and the mechanical properties, whereas the residual lignin content had no significant effect on these factors. On the other hand, high lignin content turned spruce nanopapers yellowish and, together with hemicelluloses, reduced the strain-at-break values. Finally, when no surface derivatization was applied to holocellulose and cellulose samples before defibration, the controlled preservation of residual lignin and hemicelluloses on the CNFs indicate to be crucial for the process. This simplified method of CNF preparation presents great potential for forest-based industries as a way to use forestry waste (e.g., branches, stumps, and sawdust) to produce CNFs and, consequently, diversify the product range and reach new markets.

  • 2.
    Giummarella, Nicola
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Fundamental Aspects of Lignin Carbohydrate Complexes (LCC): Mechanisms, Recalcitrance and Material concepts2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Covalent bonds between lignin and carbohydrates, forming a matrix referred to as lignin carbohydrate complexes (LCC), remain one of the most controversial topics in wood chemistry. A key issue is whether they are formed during chemical and mechanical pretreatments of the compact wood structure or actually present in wood prior to isolation. A fundamental understanding of their origin and reactivity is vital to unravel their role in wood formation and recalcitrance. Recalcitrance, specifically, has affected the successful development of effective and clean fractionation of wood polymers.

    To address the above-mentioned concerns, we have developed a novel mild universal and quantitative fractionation protocol of LCC that, when combined with robust spectroscopic analytical tools, including a variety of NMR techniques, GC MS and SEC, reveals deeper insights into the molecular structure of LCC.

    This method was applied to both hardwood and softwood LCCs and revealed interesting findings on molecular-level regulatory mechanism for lignin carbohydrate (LC) bond formation such as the role of acetylation in hemicelluloses. Moreover, the role of LC bonds on recalcitrance during subcritical water extraction was unveiled.

    Bio-mimicking in vitro lignin polymerization was adopted to investigate whether LC bonds are native or formed during isolation from wood. For the first time, direct evidence lending support that they are formed in wood cells was demonstrated, thus corroborating the mechanisms suggested in the literature.  

    Furthermore, based on the overall LCC study, we suggest a sequence for how LC bonds may form in vitro.

    Finally, of special interest to material science, the unveiled LC bond formation mechanism inspired a green, biomimetic, one-pot synthesis of functionalized lignin starting from monomeric components. Excellent selectivity of functionalization is reported and production of lignin-based recyclable materials, based on the premise of this functionalization philosophy, is discussed.

    The full text will be freely available from 2019-05-15 11:59
  • 3.
    Giummarella, Nicola
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Gioia, Claudio
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Department of Civil, Chemical, Environmental and Materials Engineering. Universita´ di Bologna.
    Lawoko, Martin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    A One-Pot Biomimetic Synthesis of Selectively Functionalized Lignins from Monomers: A Green Functionalization Platform2018In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270Article in journal (Refereed)
    Abstract [en]

    Lignin is the most abundant renewable source of phenolic compound with great application potential in renewable materials, biofuels and platform chemicals. Current technology for producing cellulose-rich fibers co-produces heterogeneous lignin, which includes an untapped source of monomeric phenolics. One such monomer also happen to be the main monomer in soft wood lignin biosynthesis, namely coniferyl alcohol. Herein, we investigate the potential of coniferyl alcohol as a platform monomer for the biomimetic production of tailored functionalized oligolignols with desirable properties for material synthesis. Accordingly, a bifunctional molecule with at least one carboxyl-ended functionality is included with coniferyl alcohol in biomimetic lignin synthesis to, in one-pot, produce a functionalized lignin. The functionalization mechanism is a nucleophilic addition reaction to quinone methide intermediate of lignin polymerization. The solvent systems applied were pure water or 50% aqueous acetone. Several bi-functional molecules differing in the second functionality were successfully inserted in the lignin demonstrating the platform component of this work. Detailed characterizations were performed by a combination of NMR techniques which include 1H NMR, COSY-90, 31P NMR, 13C NMR, 13C APT, HSQC, HMBC and HSQC TOCSY. Excellent selectivity towards benzylic carbon and high functionalization degree were noted. The structure of lignin was tailored through solvent system choice, with the 50% aqeuous acetone producing a skeletal structure favorable for high functionalization degrees. Finally, material concepts are demonstrated using classical Thiol-ene- and Diels Alder- chemistries to show potential for thermoset- and thermoplastic- concepts, respectively. The functionalization concept presents unprecedentent opportunities for green production of lignin-based recyclable biomaterials.

  • 4.
    Huang, Tianxiao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Li, Dongfang
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Water repellency improvement of cellulosic textile fibers by betulin and a betulin-based copolymer2018In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 3, p. 2115-2128Article in journal (Refereed)
    Abstract [en]

    Betulin is a naturally abundant and hydrophobic compound in the outer bark of birch and can readily be obtained by solvent extraction. Here, solutions of betulin were used to treat cotton fabrics and improve their water repellency. Cotton fabric impregnated in a solution of betulin in ethanol showed a contact angle for water of approximately 153A degrees and reached a water repellency score of 70 according to a standard water repellency test method. A betulin-terephthaloyl chloride (TPC) copolymer was synthesized. Both betulin and betulin-TPC copolymer were characterized by nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy. The copolymer was characterized by size exclusion chromatography and differential scanning calorimetry. When impregnated with a solution of betulin-TPC copolymer in tetrahydrofuran, a cotton fabric showed a water contact angle of 151A degrees and also reached a water repellency score of 70. Films based on betulin and betulin-TPC copolymer were prepared and coated onto the surface of the fabrics by compression molding. These coated fabrics showed water contact angles of 123A degrees and 104A degrees respectively and each reached a water repellency score of 80.

  • 5.
    Moser, Carl
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Backlund, Hanéle
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Lindström, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Henriksson, Gunnar
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Xyloglucan for estimating the surface area of cellulose fibers2018In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 33, no 2, p. 194-199Article in journal (Refereed)
    Abstract [en]

    The hemicellulose xyloglucan can be utilized to measure exposed cellulose surfaces for pulp fibers. This was shown by correlating a refining series with the adsorbed amount of xyloglucan, and by swelling cellulose fibers to various degrees by increasing the charge density. The method is specific to cellulose and could be used to quantify refining or to determine hornification.

  • 6.
    Moser, Carl
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology. KTH Royal Institute of Technology.
    Backlund, Hanéle
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Louise, Drenth
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gunnar, Henriksson
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Mikael E., Lindström
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Xyloglucan adsorption for measuring the specific surface area on various never-dried cellulose nanofibers2018In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 33, no 2, p. 186-193Article in journal (Refereed)
    Abstract [en]

    In this paper, we explore xyloglucan adsorption to cellulose nanofibers as a method for the evaluation of their quality (i. e., the degree of disintegration) and the accessible surface area in the wet state and at low ionic strength. This method was shown to be capable of estimating the surface areas of 14 different cellulose nanofiber qualities from both hardwood and softwood with different pretreatments, including enzymatic hydrolysis using a monocomponent endoglucanase, TEMPO-mediated oxidation, and carboxymethylation. The cellulose surface measured using this method showed a correlation with the degree of disintegration expressed as transmittance for different concentrations of xyloglucan.

  • 7.
    Moser, Carl
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Henriksson, Gunnar
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Lindström, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Improved dispersibility of once-dried cellulose nanofibers in the presence of glycerol2018In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669Article in journal (Refereed)
    Abstract [en]

    To investigate the dispersibility of dried cellulose nanofibers (CNFs), various additions (glycerol, octanol, glycol, and sodium perchlorate) were added to CNFs prior to drying. Glycerol was the only species to show any significant effect on re-dispersibility. The sedimentation was slower, and the transmittance of the solution was comparable to that of its undried counterpart. Increasing the amount of glycerol showed a clear trend with regard to dispersibility. The mechanical properties of films were maintained for samples that were dried and redispersed in the presence of glycerol.

  • 8.
    Ottenhall, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Antimicrobial materials from cellulose using environmentally friendly techniques2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The transition to a more biobased society introduces both new opportunities and new challenges as we replace nonrenewable materials with renewable alternatives. One important challenge will be to control microbial growth on materials, both to protect the materials from biological degradation and to prevent the spread of infections and toxins that can cause illness.

    In this thesis, both existing and new types of cellulose-based materials were treated with environmentally friendly alternatives to usual biocides to prevent microbial growth and remove bacteria from water. Two types of antimicrobial systems were studied, and the antimicrobial effects were evaluated for bacteria and fungi using both model organisms and wild-type cultures.

    The first antimicrobial approach employed was a nonleaching and contact-active layer-by-layer adsorption of polyelectrolytes to provide the cellulose fibers with a cationic surface charge, which attracts and captures bacteria onto the fiber surface. The study showed that paper filters with pores much larger than bacteria could remove more than 99.9 % of E. coli from water when used in filtration mode. The polyelectrolyte-modified materials showed a good antibacterial effect but did not prevent fungal growth.

    The second approach was to utilize biobased compounds with antimicrobial properties, which were applied to cellulose fiber foam materials. Chitosan and extractives from birch bark were selected as biobased options for antimicrobial agents. Two types of cellulose fiber foam materials were developed and evaluated for their antimicrobial properties.

    This thesis shows the importance of understanding both the application and the targeted microorganism when selecting an environmentally friendly antimicrobial system for treating biobased materials. It highlights that a good understanding of both material science and microbiology is important when designing new antimicrobial materials.

  • 9.
    Ottenhall, Anna
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Henschen, Jonatan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Illergård, Josefin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Cellulose-based water purification using paper filters modified with polyelectrolyte multilayers to remove bacteria from water through electrostatic interactions2018In: Environmental Science: Water Research & Technology, ISSN 20531400Article in journal (Refereed)
    Abstract [en]

    Filtration is a common way to obtain pure drinking water by removing particles and microorganisms based on size exclusion. Cellulose-based filters are affordable and biobased option for the removal of particles but bacteria are usually too small to be removed by size exclusion alone. In this article, the surfaces of cellulose fibres in two types of commercial paper filters have been given a positive net charge to trap bacteria through electrostatic interactions without releasing any biocides. The fibres were modified with the cationic polyelectrolyte polyvinylamine polymer in single layers (1 L) or in multilayers together with the anionic polyelectrolyte polyacrylic acid (3 L or 5 L) using a water-based process at room temperature. Filtration tests show that all filters, using both types of filter papers and a number of layers, can physically remove more than 99.9% of E. coli from water and that the 3 L modified filters can remove more than 97% of cultivatable bacteria from natural water samples. The bacterial reduction increased with increasing number of filter sheets used for the filtration and the majority of the bacteria were trapped in the top sheets of the filter. The results show the potential for creating water purification filters from bio-based everyday consumable products with a simple modification process. The filters could be used in the future for point-of-use water purification that may be able to save lives without releasing bactericides.

  • 10.
    Ottenhall, Anna
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Illergård, Josefin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Water Purification Using Functionalized Cellulosic Fibers with Nonleaching Bacteria Adsorbing Properties2017In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 51, p. 7616-7623Article in journal (Refereed)
    Abstract [en]

    Portable purification systems are easy ways to obtain clean drinking water when there is no large-scale water treatment available. In this study, the potential to purify water using bacteria adsorbing cellulosic fibers, functionalized with polyelectrolytes according to the layer-by-layer method, is investigated. The adsorbed polyelectrolytes create a positive charge on the fiber surface that physically attracts and bonds with bacteria. Three types of cellulosic materials have been modified and tested for the bacterial removal capacity in water. The time, material-water ratio and bacterial concentration dependence, as well as the bacterial removal capacity in water from natural sources, have been evaluated. Freely dispersed bacteria adsorbing cellulosic fibers can remove greater than 99.9% of Escherichia coli from nonturbid water, with the most notable reduction occurring within the first hour. A filtering approach using modified cellulosic fibers is desirable for purification of natural water. An initial filtration test showed that polyelectrolyte multilayer modified cellulosic fibers can remove greater than 99% of bacteria from natural water. The bacteria adsorbing cellulosic fibers do not leach any biocides, and it is an environmentally sustainable and cheap option for disposable water purification devices.

  • 11.
    Ottenhall, Anna
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Seppänen, Tiinamari
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Water-stable cellulose fiber foam with antimicrobial properties for bio based low-density materials2016In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 5, p. 2599-2613Article in journal (Refereed)
    Abstract [en]

    New bio-based packaging materials are highly interesting for replacing conventional fossil based products for a more sustainable society. Water-stable cellulose fiber foams have been produced in a simple one-batch foam-forming process with drying under ambient conditions. The cellulose fiber foams have a low density (33–66 kg/m3) and can inhibit microbial growth; two highly valuable features for insulating packaging materials, especially in combination with stability in water. Cationic chitosan and/or polyvinylamine have been added during the foam-forming process to give the foams water-stability and antimicrobial properties. The structural and mechanical properties of the cellulose fiber foams have been studied and the antimicrobial properties have been evaluated with respect to both Escherichia coli, a common model bacteria and Aspergillus brasiliensis, a sporulating mold. The cellulose foams containing chitosan had both good water-stability and good antibacterial and antifungal properties, while the foams containing PVAm did disintegrate in water and did not inhibit fungal growth when nutrients were added to the foam, showing that it is possible to produce a bio-based foam material with the desired characters. This can be an interesting low-density packaging material for protection from both mechanical and microbial damage without using any toxic compounds.

  • 12.
    Tagami, Ayumu
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology. Nippon Paper Industries Co., Ltd. .
    Towards molecular weight-dependent uses of kraft lignin2018Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    There is growing demand for a more efficient use of polymers that originate from renewable feedstocks due to the depleting supply of fossil fuels, based on economic and environmental reasons. As a result, lignin has attracted renewed interest as a resource for various bioproducts. Lignin is a natural biopolymer with a high carbon content and is composed of aromatic moieties, with a high level of polar functionalities. This makes it a unique precursor for certain high-value applications, such as in biofuels, bioplastics, composite materials, carbon fibers and activated carbons and as a source of phenolic monomers and fine chemicals.

    Industrial lignins are formed as byproducts of pulping processes (such as kraft, sulfite or alkaline pulping) or result from the biorefining process, where carbohydrates are used for sugar production. Lignin’s intrinsic structure is significantly modified during the processing of lignocellulose, resulting in the formation of more diverse, condensed and less reactive raw materials. Since molecular mass and polydispersity are the most important parameters affecting the chemical reactivity and thermal properties of lignin, additional process steps to improve the quality of crude technical lignins, including kraft lignin, are needed. Solvent extraction is a potentially useful technique for further improving the polydispersity of technical lignins.

    This work summarizes the impact of solvent fractionation on the chemical structure, antioxidant activity, heating value, and thermal and sorption properties of industrial hardwood and softwood kraft lignins. The purpose was to understand the correlation between certain structural features in the lignin fractions and their properties to select the appropriate solvent combinations for specific applications of lignin raw materials.

    Four common industrial solvents, namely, ethyl acetate, ethanol, methanol and acetone, in various combinations were used to separate both spruce and eucalyptus kraft lignins into fractions with lower polydispersities. Gel-permeation chromatography analysis was used to evaluate the efficiency of the chosen solvent combination for lignin fractionation. The composition and structure of the lignin material were characterized by elemental analysis, analytical pyrolysis (Py-GC/MS/FID) and 31P NMR spectroscopy. The thermal properties of the lignin samples were studied by thermogravimetric analysis. Proximate analysis data (ash, volatile components, organic matter and fixed carbon) were obtained through the direct measurement of weight changes during the analysis, while the high heating values (in MJ/kg) were calculated according to equations suggested in the literature. The sorption properties of fractionated kraft lignins were studied with respect to methylene blue dye.

    Additionally, lignin fractions with different molecular weights (and therefore various chemical structures) that were isolated from both softwood and hardwood kraft lignins were incorporated into a tunicate cellulose nanofiber (CNF)-starch mixture to prepare 100% bio-based composite films. The aim was to investigate the correlation between lignin diversity and film performance. The transmittance, density and thermal properties of the films were investigated, as were their mechanical properties, including the tensile stress and Young’s modulus.

    This part of the study addressed the importance of lignin diversity on composite film performance, which could be helpful for tailoring lignin applications in bio-based composite materials based on the material’s specific requirements.

  • 13.
    Tagami, Ayumu
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology. Nippon paper Industries Co., Ltd..
    Gioia, Claudio
    University of Bologna.
    Lauberts, Maris
    Latvian State Institute of Wood Chemistry.
    Budnyak, Tetyana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Moriana, Rosana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. HIS-University of Skövde.
    Lindström, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Sevastyanova, Olena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Solvent fractionation of softwood and hardwood kraft lignins for more efficient uses: compositional, structural, thermal, antioxidant and sorption propertiesManuscript (preprint) (Other academic)
    Abstract [en]

    This work summarizes the impact of solvent fractionation on the chemical structure, antioxidant activity, heating values, and thermal and sorption properties of industrial hardwood and softwood kraft lignins. The aim was to develop a simple approach for the obtaining of lignin fractions with a tailored properties for the certain material applications.  Four common industrial solvents, namely, ethyl acetate, ethanol, methanol and acetone, in various combinations efficiently separated both spruce and eucalyptus kraft lignins into fractions with low polydispersities. The ethanol fraction of spruce and the ethyl acetate fraction of eucalyptus afforded the highest yields. Gel-permeation chromatography analysis was used to evaluate the efficiency of the chosen solvent combination for lignin fractionation. The composition and structure of the lignin material was characterized by elemental analysis, analytical pyrolysis (Py-GC/MS/FID) and 31P NMR spectroscopy. The thermal properties of the lignin samples were studied by thermogravimetric analysis. Proximate analysis data (ash, volatile components, organic matter and fixed carbon) were obtained through the direct measurement of weight changes in each experimental curve, and the high heating values (in MJ/kg) were calculated according to equations suggested in the literature. The sorption properties of fractionated kraft lignins were studied with respect to methylene blue dye. The clear correlation between certain structural features in the lignin fractions and the properties of the lignin provides useful information for selecting the appropriate solvent combinations for specific applications of lignin raw materials, including as antioxidants, biofuels or sorbents in water treatment processes.

    The full text will be freely available from 2019-09-14 15:00
  • 14.
    Tagami, Ayumu
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology. Nippon paper Industries Co., Ltd. .
    Zhao, Yadong
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Dobele, Galina
    Latvian State Institute of Wood Chemistry.
    Lindström, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, Superseded Departments (pre-2005), Fibre and Polymer Technology. KTH, Superseded Departments (pre-2005), Pulp and Paper Technology.
    Sevastyanova, Olena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Lignin-modified tunicate cellulose nanofiber (CNF)-starch composites: impact of lignin diversity on film performanceManuscript (preprint) (Other academic)
    Abstract [en]

    Lignin fractions having different molecular weights and varied chemical structures isolated from kraft lignins of both softwood and hardwood via a sequential solvent fractionation technique were incorporated into a tunicate cellulose nanofibers (CNF) - starch mixture to prepare 100% bio-based composite films. The aim was to investigate the correlation between lignin diversity and film performance. It was confirmed that lignin’s distribution in the films was dependent on the solvents used for fractionation (acetone > methanol > ethanol > ethyl acetate) and influenced the optical properties of the films. The -OH group content and molecular weight of lignin were positively related to film density. In general, the addition of lignin fractions led to the thermal stability decrease and the Young's modulus increase of the composite films. The modulus of the films was found to decrease as the molecular weight of lignin increased, and a higher amount of carboxyl and phenolic -OH groups in the lignin fraction resulted in films with higher stiffness. The thermal analysis showed higher char content formation for lignin-containing films in a nitrogen atmosphere with increased molecular weight. In an oxygen atmosphere, the phenol contents, saturated side chains and short chain structures of lignin had impacts on the maximum decomposition temperature of the films, confirming the positive relationship between the antioxidant ability of lignin and thermo-oxidative stability of the corresponding film. This study addresses the importance of lignin diversities on composite film performance, which could be helpful for tailoring lignin’s applications in bio-based materials based on their specific characteristics.

    The full text will be freely available from 2019-09-14 15:00
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