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  • 1.
    Chen, Chao
    et al.
    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.
    Antibacterial evaluation of CNF/PVAm multilayer modified cellulose fiber and cellulose model surface2018In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 33, no 3, p. 385-396Article in journal (Refereed)
    Abstract [en]

    Earlier studies have shown that 3-layer-modified cellulose fibers with poly(acrylic acid) (PAA) as the middle layer between two cationic polyelectrolyte polyvinylamine (PVAm) layers have strong antibacterial efficacy in terms of both bacteria adsorption and bacterial growth inhibition. In the present work, the fossil-based PAA middle layer was replaced by sustainable wood-based cellulose nano-fibrils (CNF), i. e., the fibers were modified by a 3-layer PVAm/CNF/PVAm system. Interestingly, the antibacterial efficacy of this system was greater than that of the previous PVAm/PAA/PVAm system. A higher salt concentration and lower assembly pH in the multilayer build-up resulted in better bacterial reduction. As the surface of a cellulose fiber is heterogeneous, making it difficult to characterize and visualize at high resolution, more homogeneous cellulose model surfaces were prepared by spin coating the dissolved cellulose fiber onto a silica surface to model the fiber surface. With increasing ionic strength, more aggregated and heterogeneous structures can be observed on the PVAm/CNF/PVAm modified model surfaces. The adsorbed bacteria distributed on the structured surfaces were clearly seen under fluorescence microscopy. Adsorbed amounts of bacteria on either aggregate or flat regions were quantified by scanning electron microscopy (SEM). More adsorbed bacteria were clearly seen on aggregates than on the flat regions at the surfaces. Degrees of bacteria deformation and cell damage were also seen under SEM. The surface roughness of the modified model surfaces was examined by atomic force microscopy (AFM), and a positive correlation was found between the surface roughness and the bacterial adhesion. Thus, an additional factor that controls adhesion, in addition to the surface charge, which is probably the most dominant factor affecting the bacteria adhesion, is the surface structures, such as roughness. 

  • 2.
    Chen, Chao
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Illergård, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Effect of cationic polyelectrolytes in contact-active antibacterial layer-by-layer functionalization2017In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 71, no 7-8, p. 649-658Article in journal (Refereed)
    Abstract [en]

    Contact-active surfaces have been created by means of the layer-by-layer (LbL) modification technique, which is based on previous observations that cellulose fibers treated with polyelectrolyte multilayers with polyvinylamine (PVAm) are perfectly protected against bacteria. Several different cationic polyelectrolytes were applied, including PVAm, two different poly(diallyl dimethyl ammonium chloride) polymers and two different poly(allylamine hydrochloride) polymers. The polyelectrolytes were self-organized in one or three layers on cellulosic fibers in combination with polyacrylic acid by the LbL method, and their antibacterial activities were evaluated. The modified cellulose fibers showed remarkable bacterial removal activities and inhibited bacterial growth. It was shown that the interaction between bacteria and modified fibers is not merely a charge interaction because a certain degree of bacterial cell deformation was observed on the modified fiber surfaces. Charge properties of the modified fibers were determined based on polyelectrolyte titration and zeta potential measurements, and a correlation between high charge density and antibacterial efficiency was observed for the PVAm and PDADMAC samples. It was demonstrated that it is possible to achieve antibacterial effects by the surface modification of cellulosic fibers via the LbL technique with different cationic polyelectrolytes.

  • 3.
    Chen, Chao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Royal Inst Technol KTH, Fibre & Polymer Technol, Stockholm, Sweden..
    Illergård, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Royal Inst Technol KTH, Fibre & Polymer Technol, Stockholm, Sweden..
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Royal Inst Technol KTH, Fibre & Polymer Technol, Stockholm, Sweden..
    Ek, Monica
    Royal Inst Technol KTH, Fibre & Polymer Technol, Stockholm, Sweden..
    Evaluation of Antibacterial functionalizations of CNF/PVAm multilayer modified cellulose fibre and surface studies on silica model surface2017In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 253Article in journal (Other academic)
  • 4.
    Chen, Chao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Pettersson, Torbjörn
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Illergård, Josefin
    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.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Influence of Cellulose Charge on Bacteria Adhesion and Viability to PVAm/CNF/PVAm-Modified Cellulose Model Surfaces2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602Article in journal (Refereed)
    Abstract [en]

    A contact-active antibacterial approach based on the physical adsorption of a cationic polyelectrolyte onto the surface of a cellulose material is today regarded as an environment-friendly way of creating antibacterial surfaces and materials. In this approach, the electrostatic charge of the treated surfaces is considered to be an important factor for the level of bacteria adsorption and deactivation/killing of the bacteria. In order to clarify the influence of surface charge density of the cellulose on bacteria adsorption as well as on their viability, bacteria were adsorbed onto cellulose model surfaces, which were modified by physically adsorbed cationic polyelectrolytes to create surfaces with different positive charge densities. The surface charge was altered by the layer-by-layer (LbL) assembly of cationic polyvinylamine (PVAm)/anionic cellulose nanofibril/PVAm onto the initially differently charged cellulose model surfaces. After exposing the LbL-treated surfaces to Escherichia coli in aqueous media, a positive correlation was found between the adsorption of bacteria as well as the ratio of nonviable/viable bacteria and the surface charge of the LbL-modified cellulose. By careful colloidal probe atomic force microscopy measurements, it was estimated, due to the difference in surface charges, that interaction forces at least 50 nN between the treated surfaces and a bacterium could be achieved for the surfaces with the highest surface charge, and it is suggested that these considerable interaction forces are sufficient to disrupt the bacterial cell wall and hence kill the bacteria.

  • 5.
    Ek, Monica
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Engström, Ann-Charlott
    Henriksson, Gunnar
    Increase Reactivity of Dissolving Pulps by different pretreatments2006Conference paper (Refereed)
  • 6.
    Ek, Monica
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gellerstedt, Göran
    Henriksson, Gunnar
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ljungberg Textbook: Pulp and Paper Chemistry and Technology2007Book (Refereed)
  • 7.
    Ek, Monica
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Illergård, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Chen, Chao
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Biointeractive fibers with antibacterial properties2016In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 251Article in journal (Other academic)
  • 8.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Li, Dongfang
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Henschen, Jonatan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Esterification and hydrolysis of cellulose using oxalic acid dihydrate in a solvent-free reaction suitable for preparation of surface-functionalised cellulose nanocrystals with high yield2017In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 19, p. 5564-5567Article in journal (Refereed)
    Abstract [en]

    A one-pot esterification and hydrolysis of cellulose was carried outby treating cellulose fibres with molten oxalic acid dihydrate. Eachcellulose oxalate had a free carboxyl content above 1.2 mmol g−1and an average molecular weight of approximately 40 kDa.Aqueous suspensions of the oxalates were sonicated to preparecellulose nanocrystals with a gravimetric yield of 80.6%

  • 9.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, Fibre & Polymer Technol, Stockholm, Sweden..
    Li, Dongfang
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Royal Inst Technol, Fiber & Polymer Technol, Stockholm, Sweden..
    Le Normand, Myriam
    Galderma, Uppsala, Sweden..
    WOBAMA wood based materials based on bark2016In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 251Article in journal (Other academic)
  • 10.
    Feng, Nianjie
    et al.
    Hubei Univ Technol, Wuhan 430068, Hubei, Peoples R China.;Nanjing Forestry Univ, Nanjing 210037, Jiangsu, Peoples R China..
    Guo, Lifang
    Nanjing Forestry Univ, Nanjing 210037, Jiangsu, Peoples R China..
    Ren, Hao
    Nanjing Forestry Univ, Nanjing 210037, Jiangsu, Peoples R China..
    Xie, Yimin
    Hubei Univ Technol, Wuhan 430068, Hubei, Peoples R China..
    Jiang, Zhihua
    Auburn Univ, Alabama Ctr Paper & Bioresource Engn, Auburn, AL 36849 USA..
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Zhai, Huamin
    Nanjing Forestry Univ, Nanjing 210037, Jiangsu, Peoples R China..
    Changes in chemical structures of wheat straw auto-hydrolysis lignin by 3-hydroxyanthranilic acid as a laccase mediator2019In: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, Vol. 122, p. 210-215Article in journal (Refereed)
    Abstract [en]

    3-Hydroxyanthranilic acid (3-HAA), as a potential natural laccase mediator, was shown to mediate the oxidation of non-phenolic lignin subunits. The problem of cost and toxicity of artificial mediators could be solved to some extent by a further study about the detailed changes of lignin chemistry structures in laccase 3-HAA system (LHS). In this work, wheat straw auto-hydrolysis lignin (AL) was prepared. Oxidations of AL by LHS and laccase 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) system were then investigated, respectively. Various structural changes of AL during the oxidation were characterized by different methods including phenolic hydroxyl group determination, nitrobenzene oxidation, ozonation, gel permeation chromatography, ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy and two-dimensional nuclear magnetic resonance (2D NMR) spectroscopy. The changes in AL chemical structures were found in LHS, including unit removal, bond cleavage and biopolymerization. Compared to laccase ABTS system, a selective removal of guaiacyl-type lignin in LHS was observed, based on the results of nitrobenzene oxidation and 2D NMR analysis. The selective removal of guaiacyl-type lignin was due to improved aromatic ring cleavage and weaken lignin biopolymerization. The selectivity of guaiacyl-type lignin removal in LHS plays an important role, especially for improving bioconversion efficiency of laccase for guaiacyl-rich lignocellulosic biomass.

  • 11.
    Garcia-Garcia, Daniel
    et al.
    UPV, ITM, Plaza Ferrandiz y Carbonell 1, Alicante 03801, Spain..
    Balart, Rafael
    UPV, ITM, Plaza Ferrandiz y Carbonell 1, Alicante 03801, Spain..
    Lopez-Martinez, Juan
    UPV, ITM, Plaza Ferrandiz y Carbonell 1, Alicante 03801, Spain..
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Moriana, Rosana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Optimizing the yield and physico-chemical properties of pine cone cellulose nanocrystals by different hydrolysis time2018In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 5, p. 2925-2938Article in journal (Refereed)
    Abstract [en]

    Cellulose nanocrystals (CNCs) were isolated for the first time from pine cones (PC) by alkali and bleaching treatments and subsequent sulfuric acid hydrolysis (64%) at 45 degrees C. The influence of the hydrolytic reaction time (30, 45, and 90 min) on the yield, chemical composition and structure, and thermal stability of CNCs was evaluated. The removal of non-cellulosic constituents during the alkaline and bleaching treatment resulted in high pure cellulosic fibres. The isolation of CNCs from these cellulosic fibres at different reaction times was verified by the nano-dimensions of the individual crystals (< 3 and < 335 nm of average diameter and length, respectively). The highest yield (15%) and the optimum CNCs properties in terms of aspect ratio, thermal stability and crystallinity were obtained for an extraction time of 45 min. PC appeared to be a new promising source of cellulose fibres and CNCs with potential to be applied as reinforcement in composites and for food-packaging.

  • 12.
    Guo, Lifang
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Li, Dongfang
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Lennholm, Helena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Zhai, H.
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Structural and functional modification of cellulose nanofibrils using graft copolymerization with glycidyl methacrylate by Fe 2+ –thiourea dioxide–H 2 O 2 redox system2019In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, no 8, p. 4853-4864Article in journal (Refereed)
    Abstract [en]

    Abstract: To graft epoxy and ester functional groups onto cellulose nanofibrils (CNFs) and to overcome their poor hydrophobicity, we studied the modification of CNFs using graft copolymerization with glycidyl methacrylate (GMA) by a Fe 2+ –thiourea dioxide–H 2 O 2 initiator system (Fe 2+ –TD–H 2 O 2 ) in aqueous solution. The synthesized poly (GMA)-grafted CNF (CNF-g-PGMA) was characterized by FTIR, AFM, XRD, water contact angle, and TGA. GMA was successfully grafted onto the CNFs by Fe 2+ –TD–H 2 O 2 , the epoxy groups and ester groups of GMA were clearly present and intact in the CNF-g-PGMA, and TD is an important component of the initiator system under relatively mild graft conditions. CNF-g-PGMA may be an important intermediate because of its epoxy and ester functional groups. The main nanostructure of the CNFs was retained after graft copolymerization, and there were no obvious effects of graft copolymerization on the crystalline structure of the CNF backbone, although the crystalline index slightly decreased with the increased percentage of grafting. Graft copolymerization significantly modifies the CNF hydrophobicity. This strategy could extend the applications of CNFs into many areas. Graphical abstract: [Figure not available: see fulltext.]

  • 13.
    Henschen, Jonatan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Illergård, Josefin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Larsson, Per
    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. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Antibacterial surface modification of nanocellulosic materials2015In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 249Article in journal (Other academic)
  • 14.
    Henschen, Jonatan
    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.
    Preparation of cellulose nanomaterials via cellulose oxalates2019In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 213, p. 208-216Article in journal (Refereed)
    Abstract [en]

    Nanocellulose prepared from cellulose oxalate has been discussed as an alternative to other methods to prepare cellulose nanofibrils or crystals. The current work describes the use of a bulk reaction between pulp and oxalic acid dihydrate to prepare cellulose oxalate followed by homogenization to produce nanocellulose. The prepared nanocellulose is on average 350 nm long and 3–4 nm wide, with particles of size and shape similar to both cellulose nanofibrils and cellulose nanocrystals. Films prepared from this nanocellulose have a maximum tensile stress of 140–200 MPa, strain at break between 3% and 5%, and oxygen permeability in the range of 0.3–0.5 cm 3 μm m −2 day −1 kPa −1 at 50% relative humidity. The presented results illustrate that cellulose oxalates may be a low-cost method to prepare nanocellulose with properties reminiscent of those of both cellulose nanofibrils and cellulose nanocrystals, which may open up new application areas for cellulose nanomaterials.

  • 15.
    Huang, Tianxiao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Chen, Chao
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer 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. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH Royal Inst Technol, Stockholm, Sweden..
    Hydrophobic and antibacterial textile fibres prepared by covalently attaching betulin to cellulose2019In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal (Other academic)
  • 16.
    Huang, Tianxiao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Chen, Chao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer 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.
    Hydrophobic and antibacterial textile fibres prepared by covalently attaching betulin to cellulose2019In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, no 1, p. 665-677Article in journal (Refereed)
    Abstract [en]

    Betulin, a natural compound extractable from the outer bark of birch, can be used to improve the properties of cellulosic textile fibres. Herein, oxidation was performed to prepare carboxyl-functionalized cellulose, which was subsequently covalently attached by betulin through esterification. The surface-modified cellulosic textile fibres showed a substantially improved hydrophobicity, as indicated by a water contact angle of 136°. Moreover, the material showed excellent antibacterial properties, as indicated by over 99% bacterial removal and growth inhibition, in both Gram-positive and Gram-negative bacterial assays. The method of surface-modification of the cellulosic materials adapted in this study is simple and, to the best of our knowledge, has not been carried out before. The results of this study prove that betulin, a side-stream product produced by forest industry, could be used in value-added applications, such as for preparing functional materials. Additionally, this modification route can be envisaged to be applied to other cellulose sources (e.g., microfibrillated cellulose) to achieve the goal of functionalization.

  • 17.
    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.

  • 18. Ibarra, David
    et al.
    Köpcke, Viviana
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Influence of a monocomponent endoglucanase on different fibre raw materials: Study of accessability and reactivity2008Conference paper (Refereed)
  • 19.
    Karlsson, Josefin
    et al.
    KTH. Royal Inst Technol, S-10044 Stockholm, Sweden..
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Enarsson, Lars-Erik
    KTH.
    Wågberg, Lars
    KTH.
    CELL 283-Making biointeractive fibers: Buildup of antibacterial multilayers studied by QCM-D and SPAR2008In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 235Article in journal (Other academic)
  • 20.
    Kittikorn, Thorsak
    et al.
    Prince Songkla Univ, Dept Mat Sci & Technol, Fac Sci, Hat Yai 90112, Thailand..
    Malakul, Raminatun
    Prince Songkla Univ, Dept Microbiol, Fac Sci, Hat Yai 90112, Thailand..
    Strömberg, Emma
    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.
    Karlsson, Sigbritt
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Enhancement of mechanical, thermal and antibacterial properties of sisal/polyhydroxybutyrate-co-valerate biodegradable composite2018In: JOURNAL OF METALS MATERIALS AND MINERALS, ISSN 0857-6149, Vol. 28, no 1, p. 52-61Article in journal (Refereed)
    Abstract [en]

    Lignocellulosic biocomposite is a promising biodegradable materials, though improvement of the interfacial adhesion between cellulose fibre and polymer matrix is still challenged. Therefore, this work investigated the effect of propionylation of sisal reinforced fibre in the sisal/polyhydroxybutyrate-co-valerate (PHBV) biocomposite. Propionylation involved esterification substitution of propionic anhydride to hydroxyl group of sisal fibre, where ester group (COOR) of propionylated fibre was successfully observed by Fourier transform Infrared spectroscopy (FTIR). Then mechanical and thermal properties were evaluated and biodegradation characteristics were assessed. The tensile strength and modulus of propionylated sisal/PHBV biocomposite were greater than unmodified sisal/PHBV, which revealed better compatibility at the interface. In addition, propionate moieties of sisal fibre could induce crystalline formation of PHBV, as determined by an increase of crystalline phase. The higher decomposition temperature (Td) and activation energy (Ea) of 155 kJ.mol(-1), determined by thermal gravimetric analyser (TGA), were strong confirmation of good thermal resistance of the propionylated sisal biocomposite. The storage modulus, as characterized by dynamic mechanical thermal analyser (DMTA), also revealed the improvement of stiffness. Bacterial growth tests evaluated the inhibition of bacterial growth on the PHBV biocomposites. It was clear that propionylation of sisal fibre decreased colonization of Staphylococcus aureus (SA) and Escherichia coli (E.coli).

  • 21.
    Le Normand, Myriam
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Edlund, Ulrica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    SPRUCE BARK HEMICELLULOSES AND PECTINS: EXTRACTION AND CHARACTERIZATION2011In: 16TH INTERNATIONAL SYMPOSIUM ON WOOD, FIBER AND PULPING CHEMISTRY, PROCEEDINGS, VOLS I & II / [ed] Wang, L Kuang, S Hou, Q Cao, C Si, CL Zhang, HJ, CHINA LIGHT INDUSTRY PRESS , 2011, p. 103-106Conference paper (Refereed)
    Abstract [en]

    In industrial spruce bark, up to 20 % of the dry mass consists of non-cellulosic polysaccharides. These polysaccharides can easily be extracted with pressurized hot water and have a large potential as a starting polymeric biomass for functional materials development. In this study, spruce bark was collected directly after the debarking process. The different steps of extraction were performed in an Accelerated Solvent Extractor (ASE). Bark was first extracted with acetone at 100 degrees C to remove extractives. Spruce bark polysaccharides could then be extracted with pressurized water at 100-460 degrees C with the highest yield at 140 degrees C. They were mainly composed of glucose, arabinose and galacturonic acid units which revealed the presence of pectic substances, starch and arabinose-rich hemicelluloses, e.g. arabinans. Molecular weight estimations showed the presence of rather large polysaccharides with a Mw varying between 10 to 30 kDa, depending of the extraction conditions.

  • 22. Moliner, C.
    et al.
    Badia, J. D.
    Bosio, B.
    Arato, E.
    Kittikorn, T.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. e Department of Materials Science and Technology, Faculty of Science, Prince of Songkla University, Songkhla, Thailand .
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Teruel-Juanes, R.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ribes-Greus, A.
    Thermal and thermo-oxidative stability and kinetics of decomposition of PHBV/sisal composites2018In: Chemical Engineering Communications, ISSN 0098-6445, E-ISSN 1563-5201, Vol. 205, no 2, p. 226-237Article in journal (Refereed)
    Abstract [en]

    The decomposition behaviours of composites made of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and sisal were assessed in terms of thermal stability and decomposition kinetics, under inert and oxidative conditions, by means of multi-rate linear non-isothermal thermogravimetric experiments. A statistical design of experiments was applied to study the influence of the addition of sisal (0–10–20–30%wt), the presence coupling agent (Yes/No) and the applied conditions of work (inert or oxidative). An improvement of the thermal and thermo-oxidative stability of PHBV with the addition of sisal was observed for all cases. An accurate methodology based on iso-conversional methods was applied to simulate the potential of thermal recovery technologies, such as pyrolysis and controlled combustion, to use these biocomposites after the end of their service life. The mathematical descriptions of both thermo-chemical reactions were helpful in the evaluation of the eventual optimal operational conditions to carry out a suitable energetic valorisation. A minimum of 240°C and 137 kJ/mol of activation energy in inert conditions and 236°C and 118 kJ/mol in oxidative conditions ensured the feasibility of the reactions regardless the composition of the PHBV/sisal biocomposites, which may ease the operability of further energy valorisation with the aim to turn biowaste into new fuels.

  • 23.
    Moliner, C.
    et al.
    Univ Genoa, DICCA, Via Opera Pia 15, I-16145 Genoa, Italy.;Univ Politecn Valencia, ITM, Camino Vera S-N, E-46022 Valencia, Spain..
    Badia, J. D.
    Univ Politecn Valencia, ITM, Camino Vera S-N, E-46022 Valencia, Spain.;Univ Valencia, Escola Tecn Super Engn, Dept Engn Quim, Av Univ S-N, E-46100 Burjassot, Spain..
    Bosio, B.
    Univ Genoa, DICCA, Via Opera Pia 15, I-16145 Genoa, Italy..
    Arato, E.
    Univ Genoa, DICCA, Via Opera Pia 15, I-16145 Genoa, Italy..
    Teruel-Juanes, R.
    Univ Politecn Valencia, ITM, Camino Vera S-N, E-46022 Valencia, Spain..
    Kittikorn, Thorsak
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Prince Songkla Univ, Fac Sci, Dept Mat Sci & Technol, Hat Yai 90112, Thailand..
    Strömberg, Emma
    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.
    Karlsson, Sigbritt
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Ribes-Greus, A.
    Univ Politecn Valencia, ITM, Camino Vera S-N, E-46022 Valencia, Spain..
    Thermal kinetics for the energy valorisation of polylactide/sisal biocomposites2018In: Thermochimica Acta, ISSN 0040-6031, E-ISSN 1872-762X, Vol. 670, p. 169-177Article in journal (Refereed)
    Abstract [en]

    The thermal stability and decomposition kinetics of PLA/sisal biocomposites was discussed to evaluate the suitability of their use in energy recovery processes such as pyrolysis and combustion. The influence of the addition of sisal up to 30%wt, the presence of coupling agent, and the atmosphere of operation, i.e. inert or oxidative was discussed by means of multi-rate linear non-isothermal thermogravimetric experiments. All biocomposites showed a mean high heating value of 15 MJ/kg indicating their suitability for energy recovery processes. The thermal requirements of PLA/sisal decomposition were assessed in terms of onset decomposition temperature and apparent activation energy. A minimum of 240 degrees C and 174 kJ mol(-1) in inert environment and 225 degrees C and 190 kJ mol(-1) in oxidative environment ensured the feasibility of the reactions regardless the composition of the PLA/sisal biocomposites. The atmosphere of work lead to a greater amount of residue in case of pyrolysis reactions that would need further treatment whereas an oxidative atmosphere resulted in nearly zero final waste stream. The similar kinetics obtained for all samples regardless the amount of sisal or use of coupling agent eases the operability of energy facilities aimed of turning these biowastes into new fuels.

  • 24.
    Ottenhall, Anna
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Illergård, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Water Purification Using Functionalized Cellulosic Fibers with Nonleaching Bacteria Adsorbing Properties2017In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 13, p. 7616-7623Article in journal (Refereed)
    Abstract [en]

     Portable purifi cation 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 fi bers, functionalized with polyelectrolytes according to the layer-by-layer method, is investigated. The adsorbed polyelectrolytes create a positive charge on the fi ber surface that physically attracts and bonds with bacteria. Three types of cellulosic materials have been modifi ed 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 fi bers can remove greater than 99.9% of Escherichia coli  from nonturbid water, with the most notable reduction occurring within the fi rst hour. A fi ltering approach using modifi ed cellulosic fi bers is desirable for purifi cation of natural water. An initial fi ltration test showed that polyelectrolyte multilayer modifi ed cellulosic fi bers can remove greater than 99% of bacteria from natural water. The bacteria adsorbing cellulosic fi bers do not leach any biocides, and it is an environmentally sustainable and cheap option for disposable water purification devices.

  • 25.
    Ottenhall, Anna
    et al.
    KTH, School of Chemical Science and Engineering (CHE).
    Henschen, Jonatan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Illergård, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Bacteria adsorbing emergency water filters based on polyelectrolyte modified paperManuscript (preprint) (Other academic)
    Abstract [en]

    Water filtration is a popular way to remove particles and microorganisms from drinking water but is generally based on size exclusion of the particles. Bacteria can be modeled as small particles with a diameter of 1-2 µm, which is usually too small to be excluded by paper filters. In this article, commercial available paper filters have been surface modified by polyelectrolyte multilayer adsorption to create a positively charged filter that can trap the negatively charged bacteria through electrostatic interactions. The polyelectrolyte modified filters bind the bacteria to there surface and will thereby remove bacteria from the water instead of inactivated them through addition of biocides. The modified filters can remove more than 99.9 % of bacteria in water, depending on filter design, and has successfully been compared to a commercial cellulose water filter, based on the release of silver to inactivate bacteria. This cheap and easy modification of filter paper has potential to create disposable water purification filters that could be used in emergency situations to prevent outbreak of lethal diarrheal diseases.

  • 26.
    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 2053-1400Article 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.

  • 27.
    Ottenhall, Anna
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Illergård, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Water purification using functionalized cellulose with non-leaching bacteria adsorbing propertiesManuscript (preprint) (Other academic)
    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 cellulose functionalized with polyelectrolytes, according to the Layer-by-Layer method, is investigated. The adsorbed polyelectrolytes create a positive charge on the cellulose surface that physically attracts and bonds with bacteria. Three types of cellulose material 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 cellulose can remove greater than 99.9% of Escherichia coli from non-turbid water, with the most notable reduction occurring within the first hour. For turbid water, a filtering approach using modified cellulose fibers is desirable. This bacteria adsorbing cellulose does not leach any biocides, and it is an environmentally sustainable and cheap option for disposable water purification devices.

  • 28.
    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.

  • 29.
    Ottenhall, Anna
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Seppänen, Tiinamari
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Purification of water using cellulose: A safe way to remove bacteria2017In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 253Article in journal (Other academic)
  • 30.
    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.

  • 31.
    Ottenhall, Anna
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer 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 materials2018In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 4, 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.

  • 32.
    Sevastyanova, Olena
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Li, Dongfang
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Evaluation of Ionic Liquids as direct solvents for the manufacturing of novel products from cellulose2010Conference paper (Refereed)
  • 33. Sjödahl, Ragnar
    et al.
    Keyoumu, Ayiguli
    Axelsson, Patrik
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Dissolved wood components in the kraft pulping liquor: Effect on the rate of delignification and bleachability2003Conference paper (Refereed)
  • 34.
    Swensson, Beatrice
    et al.
    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.
    Gray, Derek G.
    McGill Univ, Dept Chem, Pulp & Paper Bldg,3420 Univ St, Montreal, PQ H3A 2A7, Canada..
    In Situ Preparation of Silver Nanoparticles in Paper by Reduction with Alkaline Glucose Solutions2018In: ACS OMEGA, ISSN 2470-1343, Vol. 3, no 8, p. 9449-9452Article in journal (Refereed)
    Abstract [en]

    Percolation of contaminated water through paper sheets containing silver nanoparticles is a promising way to provide emergency drinking water. The silver nanoparticles are deposited by the in situ reduction of silver nitrate on the cellulose fibers of an absorbent blotting paper sheet. Sodium borohydride has been used as the reductant but is toxic and expensive. Glucose is a benign alternative but is much less reactive. In this note, we demonstrate an improved way to produce silver nanoparticles in paper sheets by adding sodium hydroxide to the glucose reductant. The silver content of the sheets, measured by diffuse reflectance spectroscopy, was around 2-3 mg of silver per gram of dry paper. This was sufficient to reduce the concentration of a model Escherichia coli suspension after percolation through the sheet.

  • 35. Villaverde, Juan Jos
    et al.
    Li, Jiebing
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ligero, Pablo
    Vega, Alberto de
    Structural characterization of Acetosolve lignin from Miscanthus sinensis2008Conference paper (Refereed)
  • 36.
    Zheng, Chao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer 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.
    Bio-based fire retardant and its application in cellulose-based thermal insulation materials2018In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Article in journal (Other academic)
  • 37.
    Zheng, Chao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer 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.
    Improving fire retardancy of cellulosic thermal insulating materials by coating with bio-based fire retardants2019In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 34, no 1, p. 96-106Article in journal (Refereed)
    Abstract [en]

    Sustainable thermal insulating materials produced from cellulosic fibers provide a viable alternative to plastic insulation foams. Industrially available, abundant, and inexpensive mechanical pulp fiber and recycled textile fiber provide potential raw materials to produce thermal insulating materials. To improve the fire retardancy of low-density thermal insulating materials produced from recycled cotton denim and mechanical pulp fibers, bio-based fire retardants, such as sulfonated kraft lignin, kraft lignin, and nanoclays, were coated onto sustainable insulating material surfaces to enhance their fire retardancy. Microfibrillated cellulose was used as a bio-based binder in the coating formula to disperse and bond the fire-retardant particles to the underlying thermal insulating materials. The flammability of the coated thermal insulating materials was tested using a single-flame source test and cone calorimetry. The results showed that sulfonated kraft lignin-coated cellulosic thermal insulating materials had a better fire retardancy compared with that for kraft lignin with a coating weight of 0.8 kg/m(2). Nanoclay-coated samples had the best fire retardancy and did not ignite under a heat flux of 25 kW/m(2), as shown by cone calorimetry and single-flame source tests, respectively. These cost-efficient and bio-based fire retardants have broad applications for improving fire retardancy of sustainable thermal insulating materials.

  • 38.
    Zheng, Chao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer 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.
    Mechanism and kinetics of thermal degradation of insulating materials developed from cellulose fiber and fire retardants2019In: Journal of thermal analysis and calorimetry (Print), ISSN 1388-6150, E-ISSN 1588-2926, Vol. 135, no 6, p. 3015-3027Article in journal (Refereed)
    Abstract [en]

    The mechanism and kinetics of thermal degradation of materials developed from cellulose fiber and synergetic fire retardant or expandable graphite have been investigated using thermogravimetric analysis. The model-free methods such as Kissinger–Akahira–Sunose (KAS), Friedman, and Flynn–Wall–Ozawa (FWO) were applied to measure apparent activation energy (Ea).The increased Ea indicated a greater thermal stability because of the formation of a thermally stable char, and the decreased Ea after the increasing region related to the catalytic reaction of the fire retardants, which revealed that the pyrolysis of fire retardant-containing cellulosic materials through more complex and multi-step kinetics. The Friedman method can be considered as the best method to evaluate the Ea of fire-retarded cellulose thermal insulation compared with the KAS and two methods. A master-plots method such as the Criado method was used to determine the possible degradation mechanisms. The degradation of cellulose thermal insulation without a fire retardant is governed by a D3 diffusion process when the conversion value is below 0.6, but the materials containing synergetic fire retardant and expandable graphite fire retardant may have a complicated reaction mechanism that fits several proposed theoretical models in different conversion ranges. Gases released during the thermal degradation were identified by pyrolysis–gas chromatography/mass spectrometry. Fire retardants could catalyze the dehydration of cellulosic thermal insulating materials at a lower temperature and facilitate the generation of furfural and levoglucosenone, thus promoting the formation of char. These results provide useful information to understand the pyrolysis and fire retardancy mechanism of fire-retarded cellulose thermal insulation.

1 - 38 of 38
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