Ändra sökning
Avgränsa sökresultatet
1 - 47 av 47
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Alakalhunmaa, Suvi
    et al.
    University of Helsinki, Finland.
    Parikka, Kristi
    University of Helsinki, Finland.
    Penttilä, Paavo A.
    University of Helsinki, Finland.
    Cuberes, M. Teressa
    University of Castilla-La Mancha, Spain.
    Willför, Stefan
    Åbo Akademi University, Finland.
    Salmen, Lennart
    RISE., Innventia.
    Mikkonen, Kristi S.
    University of Helsinki, Finland.
    Softwood-based sponge gels2016Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, nr 5, s. 3221-3238Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Crosslinking-aided gelation was utilized to prepare hydrogels from softwood polysaccharides, with spruce galactoglucomannans (GGM)—a group of largely unexploited hemicelluloses—as the main component, aiming at conversion into sponge-like aerogels. Cellulose nanofibrils were used for the formation of a reinforcing network, which was further crosslinked together with a GGM matrix by ammonium zirconium carbonate, an inorganic salt that is regarded as safe for use in food packaging. The hydrogels were freeze-dried into stiff, low-density aerogels with 98 % of their volume composed of air-filled pores. When immersed in water, the aerogels absorbed water up to 37 times their initial weight, demonstrating elasticity and repeatable and reversible sponge capacity. The developed concept reassembles the wood polysaccharides in a new way, creating interesting possibilities for utilizing the abundant “green gold,” GGM. The obtained biobased materials could find application potential, for example, in the field of food packaging and could contribute in the reduction of the usage of petroleum-based plastics in the future.

  • 2.
    Almgren, K. M.
    et al.
    RISE., STFI-Packforsk.
    Kerholm, M.
    RISE., STFI-Packforsk.
    Gamstedt, E. K.
    RISE., STFI-Packforsk.
    Salmen, Lennart
    RISE., STFI-Packforsk.
    Lindström, Mikael
    RISE., STFI-Packforsk.
    Effects of moisture on dynamic mechanical properties of wood fiber composites studied by dynamic FT-IR spectroscopy2008Ingår i: Journal of reinforced plastics and composites (Print), ISSN 0731-6844, E-ISSN 1530-7964, Vol. 27, nr 16-17, s. 1709-1721Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wood fiber reinforced polylactide is a biodegradable composite where both fibers and matrix are from renewable resources. In the development of such new materials, information on mechanical behavior on the macroscopic and the molecular level is useful. In this study, dynamic Fourier transform infrared (FT-IR) spectroscopy is used to measure losses at the molecular level during cyclic tensile loading for bonds that are characteristic of the cellulosic fibers and the polylactid matrix. This molecular behavior is compared with measured macroscopic hysteresis losses for different moisture levels. The results show that moisture ingress will transfer the load from the fibers to the matrix, and that a more efficient fiber-matrix interface would diminish mechanical losses. Although the dynamic FT-IR spectroscopy method is still qualitative, this investigation shows that it can provide information on the stress transfer of the constituents in wood fiber reinforced plastics.

  • 3.
    Baker, Darren A.
    et al.
    RISE., Innventia.
    Bäckström, Marie
    RISE., Innventia.
    Salmen, Lennart
    RISE., Innventia.
    Schweinebarth, Hannah
    RISE., Innventia.
    Tomani, Per
    RISE., Innventia.
    Opportunities in lignin based carbon fibre2015Ingår i: NWBC 2015: The 6th Nordic Wood Biorefinery Conference, Espoo: VTT , 2015, s. 244-251Konferensbidrag (Refereegranskat)
    Abstract [en]

    Innventia AB's LignoBoost process enables the extraction of high purity lignin efficiently from the black liquor in kraft mills. A stream of black liquor is taken from the evaporation plant and the lignin is precipitated by acidification and filtered. The filter cake is redispersed and acidified and the resulting slurry is filtered and washed. High purity lignin can be produced at several scales, namely 10g, 1kg, 10kg and over 1,000kg. Innventia has invested significantly to demonstrate the potential of lignin as a viable feedstock for carbon fibre manufacture. Initially, the fibre melt spinning performance of the lignin is assessed using single filament melt extrusion and then melt spinning is performed at the multifilament scale, where fine fibres can be produced for conversion to carbon fibre. Oxidative thermostabilisation of the lignin fibres is carried out so that carbonisation can proceed. The effects of thermal treatment programmes and tensioning have been studied by using either thermomechanical analysis or by using test equipment specially designed to monitor carbonisation profiles with either stress or strain control. In addition, continuous processes for the conversion of lignin fibre to carbon fibre are being developed.

  • 4. Bjurhager, I.
    et al.
    Olsson, Anne-Mari
    RISE., Innventia.
    Zhang, B.
    Gerber, L.
    Kumar, M.
    Berglund, Lars A.
    Burgert, I.
    Sundberg, B.
    Salmen, Lennart
    RISE., Innventia.
    Ultrastructure and mechanical properties of populus wood with reduced lignin content caused by transgenic down-regulation of cinnamate 4-hydroxylase2010Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 11, nr 9, s. 2359-2365Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Several key enzymes in lignin biosynthesis of Populus have been down-regulated by transgenic approaches to investigate their role in wood lignification and to explore their potential for lignin modification. Cinnamate 4-hydroxylase is an enzyme in the early phenylpropanoid pathway that has not yet been functionally analyzed in Populus. This study shows that down-regulation of cinnamate 4-hydroxylase reduced Klason lignin content by 30% with no significant change in syringyl to guaiacyl ratio. The lignin reduction resulted in ultrastructural differences of the wood and a 10% decrease in wood density. Mechanical properties investigated by tensile tests and dynamic mechanical analysis showed a decrease in stiffness, which could be explained by the lower density. The study demonstrates that a large modification in lignin content only has minor influences on tensile properties of wood in its axial direction and highlights the usefulness of wood modified beyond its natural variation by transgene technology in exploring the impact of wood biopolymer composition and ultrastructure on its material properties.

  • 5. Chang, Shan-Shan
    et al.
    Salmen, Lennart
    RISE., Innventia.
    Olsson, Anne-Mari
    RISE., Innventia.
    Clair, Bruno
    Deposition and organisation of cell wall polymers during maturation of poplar tension wood by FTIR microspectroscopy2014Ingår i: Planta, ISSN 0032-0935, E-ISSN 1432-2048, Vol. 239, nr 1, s. 243-254Artikel i tidskrift (Refereegranskat)
  • 6. Dammström, S.
    et al.
    Salmen, Lennart
    RISE., STFI-Packforsk.
    Gatenholm, P.
    On the interactions between cellulose and xylan, a biomimetic simulation of the hardwood cell wall2009Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 4, nr 1, s. 3-14Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The plant cell wall exhibits a hierarchical structure, in which the organization of the constituents on different levels strongly affects the mechanical properties and the performance of the material. In this work, the interactions between cellulose and xylan in a model system consisting of a bacterial cellulose/glucuronoxylan (extracted from aspen, Populus tremula) have been studied and compared to that of a delignified aspen fiber material. The properties of the materials were analyzed using Dynamical Mechanical Analysis (DMA) with moisture scans together with dynamic Infra Red -spectroscopy at dry and humid conditions. The results showed that strong interactions existed between the cellulose and the xylan in the aspen holocellulose. The same kinds of interactions were seen in a water-extracted bacterial cellulose/xylan composite, while unextracted material showed the presence of xylan not interacting with the cellulose. Based on these findings for the model system, it was suggested that there is in hardwood one fraction of xylan that is strongly associated with the cellulose, taking a similar role as glucomannan in softwood.

  • 7.
    De Magistris, Federica
    et al.
    RISE., STFI-Packforsk.
    Salmen, Lennart
    RISE., STFI-Packforsk.
    Finite element modelling of wood cell deformation transverse to the fibre axis2008Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, nr 2, s. 240-246Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Modelling of wet wood under compression and combined shear and compression load was performed to simulate the mechanical pulping of wood chips in refiners. Experiments have shown that the wet fibre network exhibit two different deformation modes; an S-shape mode associated with compression and a brick-shape mode associated with combined shear and compression. To study the factors governing the mechanical behaviour of the fibre network a material model with the characteristics originating from the properties of the wood polymers was developed and was used in a three-dimensional finite element analysis. The effects of material properties were investigated by comparing models with anisotropic one-layer cell walls and orthotropic multi-layer cell walls. The deformation achieved both under compression and under combined shear and compression was found to be similar independent of the material constants used or the number of layers of the cells walls. This implies that the most important factor governing the deformation pattern of the fibre network is the cell structure itself.

  • 8.
    Dong, F.
    et al.
    RISE., Innventia.
    Olsson, Anne-Mari
    RISE., Innventia.
    Salmen, Lennart
    RISE., Innventia.
    Fibre morphological effects on mechano-sorptive creep2010Ingår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 44, nr 3, s. 475-483Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The increased creep rate of paper under load during moisture cycling conditions as compared to that at high constant humidity is a problem in the use of packaging materials. In order to investigate the influence of morphological factors of the fibres on the occurrence and magnitude of this phenomenon, i.e. the occurrence of mechano-sorptive creep, studies on wood fibres isolated from different parts of spruce wood were performed. Thus, creep properties were studied on earlywood and latewood fibres from both juvenile wood and mature wood. In general, latewood fibres showed a higher degree of mechano-sorptive creep than earlywood fibres, and mature wood showed a higher degree of mechano-sorptive creep than juvenile fibres. The difference in mechano-sorptive creep rate between different fibres was shown to be correlated to the differences in fibril angle. The smaller the fibril angle the higher was the mechano-sorptive creep ratio. It was suggested that at fibril angles approaching 45° wood fibres do not exhibit mechano-sorptive creep.

  • 9. Fackler, K.
    et al.
    Stevanic, Jasna S.
    RISE., Innventia.
    Ters, T.
    Hinterstoisser, B.
    Schwanninger, M.
    Salmen, Lennart
    RISE., Innventia.
    Localisation and characterisation of incipient brown-rot decay within spruce wood cell walls using FT-IR imaging microscopy2010Ingår i: Enzyme and microbial technology, ISSN 0141-0229, E-ISSN 1879-0909, Vol. 47, nr 6, s. 257-267Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Spruce wood that had been degraded by brown-rot fungi (Gloeophyllum trabeum or Poria placenta) exhibiting mass losses up to 16% was investigated by transmission Fourier transform infrared (FT-IR) imaging microscopy. Here the first work on the application of FT-IR imaging microscopy and multivariate image analysis of fungal degraded wood is presented and the first report on the spatial distribution of polysaccharide degradation during incipient brown-rot of wood. Brown-rot starts to become significant in the outer cell wall regions (middle lamellae, primary cell walls, and the outer layer of the secondary cell wall S1). This pattern was detected even in a sample with non-detectable mass loss. Most significant during incipient decay was the cleavage of glycosidic bonds, i.e. depolymerisation of wood polysaccharides and the degradation of pectic substances. Accordingly, intramolecular hydrogen bonding within cellulose was reduced, while the presence of phenolic groups increased.

  • 10. Fernandes, S.C.M.
    et al.
    Freire, C.S.R.
    Silvestre, A.J.D.
    Pascoal Neto, C.
    Gandini, A.
    Berglund, Lars A.
    Salmen, Lennart
    RISE., Innventia.
    Transparent chitosan films reinforced with a high content of nanofibrillated cellulose2010Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 81, nr 2, s. 394-401Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper reports the preparation and characterization of nanocomposite films based on different chitosan matrices and nanofibrillated cellulose (NFC) for the purpose of improving strength properties. The nanocomposite films were prepared by a simple procedure of casting a water-based suspension of chitosan and NFC, and were characterized by several techniques: namely SEM, X-ray diffraction, visible spectrophotometry, TGA, tensile and dynamic-mechanical analysis. The films obtained were shown to be highly transparent (transmittance varying between 90 and 20% depending on the type of chitosan and NFC content), flexible, displayed better mechanical properties, with a maximum increment on the Young’s modulus of 78% and 150% for high molecular weight (HCH) and water-soluble high molecular weight (WSHCH) filled chitosans, respectively; and of 200% and 320% for low molecular weight (LCH) and water-soluble filled (WSLCH) chitosans, respectively. The filled films also showed increased thermal stability, with, for example, an increase in the initial degradation temperature (Tdi) from 227 °C in the unfilled LCH film up to 271 °C in filled LCHNFC50% nanocomposite films, and a maximum degradation temperature (Td1) raising from 304 °C to 313 °C for the same materials.

  • 11.
    Giummarella, Nicola
    et al.
    KTH Royal Institute of Technology, Sweden.
    Henriksson, Gunnar
    KTH Royal Institute of Technology, Sweden.
    Salmen, Lennart
    RISE - Research Institutes of Sweden, Bioekonomi, Bioraffinaderi och energi.
    Lawoko, Martin
    KTH Royal Institute of Technology, Sweden.
    On the effect of hemicellulose removal on cellulose-lignin interactions2017Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, nr 4, s. 542-549Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In a recent study, it was suggested that there could be direct associations between cellulose and lignin in mild alkaline cooked pulps. The observation was based on studies showing that the molecular straining of lignin was similar to that of cellulose. This finding has serious ramifications for technical production of pulps as it could expand on what is known about recalcitrant lignin removal during pulping. Herein, we investigate the possible interaction between cellulose and lignin discussing possible mechanisms involved at the nano- and molecular-scales, and present support for that the removal of hemicellulose by hot water extraction or mild kraft pulping causes strong interactions between lignin and cellulose. 

  • 12.
    Guo, Juan
    et al.
    Chinese Academy of Forestry, China.
    Song, Kunlin
    Chinese Academy of Forestry, China.
    Salmen, Lennart
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Yin, Yafang
    Chinese Academy of Forestry, China; KTH Royal Institute of Technology, Sweden.
    Changes of wood cell walls in response to hygro-mechanical steam treatment2015Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 115, s. 207-214Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effects of compression combined with steam treatment (CS-treatment), i.e. a hygro-mechanical steam treatment on Spruce wood were studied on a cell-structure level to understand the chemical and physical changes of the secondary cell wall occurring under such conditions. Specially, imaging FT-IR microscopy, nanoindentation and dynamic vapour absorption were used to track changes in the chemical structure, in micromechanical and hygroscopic properties. It was shown that CS-treatment resulted in different changes in morphological, chemical and physical properties of the cell wall, in comparison with those under pure steam treatment. After CS-treatment, the cellular structure displayed significant deformations, and the biopolymer components, e.g. hemicellulose and lignin, were degraded, resulting in decreased hygroscopicity and increased mechanical properties of the wood compared to both untreated and steam treated wood. Moreover, CS-treatment resulted in a higher degree of degradation especially in earlywood compared to a more uniform behaviour of wood treated only by steam.

  • 13.
    Guo, Juan
    et al.
    Chinese Academy of Forestry, China.
    Yin, Jiangping
    Chinese Academy of Forestry, China.
    Zhang, Yonggang
    Chinese Academy of Forestry, China.
    Salmen, Lennart
    RISE - Research Institutes of Sweden, Bioekonomi. RISE., Innventia.
    Yin, Yafang
    Chinese Academy of Forestry, China.
    Effects of thermo-hygro-mechanical (THM) treatment on the viscoelasticity of in-situ lignin2017Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 71, nr 6, s. 455-460Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For producing wood products without fractures based on thermo-hygro-mechanical (THM) treatments, it is essential to understand how steaming and compression change the wood softening and cell wall components. In this paper, the effects of compression combined with steam treatment (CS) on the viscoelasticity of the in-situ lignin of Chinese fir has been investigated through dynamic mechanical analysis (DMA) under fully saturated conditions. Several variations were studied, such as the softening temperature (Tg) and apparent activation energy (ΔHa) of the softening process in response to CS treatment conditions (such as steam temperature and compression ratio) under separate consideration of earlywood (EW) and latewood (LW). No difference between EW and LW with respect to the viscoelasticity was noted. Tg and ΔHa of the lignin softening were nearly unaffected by the compression ratio, but were highly influenced by the steam temperature. The Tg decreased significantly with CS treatments at or above 160oC, but showed no appreciable change, compared to the native wood, at the lower steaming temperature of 140oC. ΔHa increased at higher steam temperatures, while ΔHa showed a decreasing tendency with decreasing Tg. This indicates that lignin undergoes a simultaneous depolymerization as well as a condensation during CS treatment.

  • 14.
    Guo, Juan
    et al.
    Chinese Academy of Forestry, China.
    Zhou, Haibin
    Chinese Academy of Forestry, China.
    Stevanic Srndovic, Jasna
    RISE - Research Institutes of Sweden, Bioekonomi, Bioraffinaderi och energi.
    Dong, Mengyu
    Chinese Academy of Forestry, China.
    Yu, Min
    Chinese Academy of Forestry, China.
    Salmen, Lennart
    RISE - Research Institutes of Sweden, Bioekonomi, Bioraffinaderi och energi.
    Yin, Yafang
    Chinese Academy of Forestry, China.
    Effects of ageing on the cell wall and its hygroscopicity of wood in ancient timber construction2018Ingår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 52, nr 1, s. 131-147Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An important traditional load bearing member in oriental ancient timber structure buildings, i.e. Huagong (flower arm), was selected to explore the alterations in cell wall components and hygroscopic properties of wood during long time ageing. This archaeological poplar (Populus spp.) wood with cal. BP 690: BP 790 was studied from the wood surface and inwards by means of imaging FTIR spectroscopy, X-ray diffraction and dynamic vapour sorption. The deterioration of the archaeological wood mainly displayed a depolymerization of glucomannan and lignin as well as a hydrolysis of the glucuronic acid of xylan and of the aromatic C–O groups in the condensed lignins or lignin–carbohydrate complexes. Furthermore, the degradation promoted the rearrangement of the cellulose molecules in adjacent microfibrils. The cellulose crystallites in the archaeological wood were therefore packed more tightly and had larger diameter. The structural alterations of wood cell wall components and a decrease in crystallinity contributed to an increase in the number of moisture bonding sites and led to an increase in both the equilibrium moisture content of the archaeological wood in the entire RH range as well as an increase in hysteresis.

  • 15.
    Hammar, Lars-Åke
    et al.
    RISE., STFI-Packforsk.
    Salmen, Lennart
    RISE., STFI-Packforsk.
    Sandberg, C.
    Sundström, L.
    The effect of process conditions on pulp quality development at low consistency refining of mechanical pulp - TMP2009Ingår i: 2009 International Mechanical Pulping Conference : proceedings: IMPC 2009, 2009, s. 182-185Konferensbidrag (Refereegranskat)
    Abstract [en]

    Low consistency refining (LC) as a second refining stage, after a HC-defibration is an energy-efficient process solution. This HC-LC concept has for some time been explored in pilot scale and shown promising results. However it is clear that in order to obtain an optimal development of pulp properties the LC-refining has to be optimized with regard to process conditions. In this study the effects of temperature, pH, and specific edge load in the LC-refining on the pulp quality were investigated. For this purpose a mobile LC refiner rig placed after a primary stage HC mill refiner in the Braviken Paper mill, Holmen Paper was used. The trials show that energy savings are possible with preserved properties in the production of mechanical pulp. High temperature, high pH and low specific edge load were indicated to be preferable for both the tensile index development and for preserving the fibre length of the pulp. An increased degree of refining developed as expected the tensile index but too high specific energy resulted in some fibre shortening.

  • 16.
    Hammar, Lars-Åke
    et al.
    RISE., Innventia.
    Salmen, Lennart
    RISE., Innventia.
    Sandberg, C.
    Sundström, L.
    The effect of process conditions on pulp quality development in low consistency refining of mechanical pulp - TMP2010Ingår i: Appita journal, ISSN 1038-6807, Vol. 63, nr 5, s. 377-380Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High consistency (HC) defibration followed by secondary stage low consistency refining (LC) is an energy efficient process in mechanical pulping that has been explored for some time. In this study the effects of temperature, pH, specific edge load and specific energy on pulp quality have been investigated for LC refining using a mobile LC refiner rig placed after a primary stage HC refiner In the Braviken Paper mill. The trials showed that the specific energy consumption in production of mechanical pulp can be reduced with at least 15% with preserved pulp properties. High temperature, pH over 7 and low specific edge load were advantageous both for tensile index development and for preserving the fibre length of the pulp. The development of other pulp properties such as shives content and light scattering coefficient, as a function of freeness, were comparable for the second stage LC- and HC-refining.

  • 17.
    Jetsu, Petri
    et al.
    VTT Technical Research Centre of Finland, Finland.
    Pöhler, Tiina
    VTT Technical Research Centre of Finland, Finland.
    Barraud, Vincent
    Soprema, France.
    Seppänen, Rauni
    Holmen, Sweden.
    Salmen, Lennart
    RISE., Innventia.
    Lecourt, Michael
    FCBA, France.
    Wood-based thermal insulation materials2016Ingår i: Proceedings of the 14th European workshop on lignocellulosics and pulp, 2016, Vol. 2, s. 341-345Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    A research project has been undertaken with the aim of developing wood-based cellulosic thermal insulation panel material manufactured by foam forming with high performance and to explore the possibilities of creating a new bio-based cellulosic in-situ spray-on thermal insulation foam to replace traditional spray-on plastics insulation foams. Insulation boards were manufactured from 100% softwood and a mixture of softwood and microfibrillated cellulose (MFC). The foaming surfactant used was sodium dodecyl sulphate (SDS). The materials made of softwood and MFC mixtures were made by layering. The thermal conductivity behaviour of the boards was investigated. It has been demonstrated that by using foam forming technology, nanofibrillated cellulose and softwood kraft pulp, it was possible to create high bulk fibre networks with good thermal insulation properties that simultaneously had outstanding high air flow resistivity in relation to the total density of the material. The results obtained were affected by board density. Air flow decreased with board bulk density, due to higher tortuosity of fibrous structure. Air flow resistance increased with layering strategy, with MFC layer enhancing the performance of boards to limit air going across the board.

  • 18.
    Kleinhans, Henrik
    et al.
    RISE., Innventia.
    Salmen, Lennart
    RISE., Innventia.
    Development of lignin carbon fibers: Evaluation of the carbonization process2016Ingår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 133, nr 38, artikel-id APP43965Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The use of lignin as a renewable resource for the production of less-expensive carbon fibers has in recent years attracted great interest. In order to develop the strength properties, the stabilization and carbonization processes have to be optimized. For this reason, the process parameters during carbonization have here been studied on stabilized lignin fibers in the temperature interval from 300 to 1300 °C. The effects of temperature, heating rate, and straining of fibers during carbonization on the strength properties of carbon fibers were investigated. The heating rate, in the range from 1 to 40 °C/min, was shown to have no effect on the property development of the fibers. During carbonization with no load applied to the fibers, a shrinkage of 20% was noted. Counteracting the shrinkage by imposing a load on the fibers during the carbonization resulted in fibers with a greater stiffness. The tensile strength was not, however, affected by this loading.

  • 19.
    Lecourt, Micheal
    et al.
    FCBA, France.
    Pöhler, Tiina
    VTT, Finland.
    Hornatowska, Joanna
    RISE - Research Institutes of Sweden, Bioekonomi.
    Salmen, Lennart
    RISE - Research Institutes of Sweden, Bioekonomi, Bioraffinaderi och energi.
    Jetsu, Petri
    VTT, Finland.
    Density profiles of novel kraft pulp and TMP based foam formed thermal insulation materials observed by X-ray tomography and densitometry2018Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, nr 5, s. 397-403Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    X-ray tomography and densitometry (XRT and XRD) were applied to characterise wood fibre based insulation materials, which were produced by the foam forming technology. XRT is a high resolution approach with long measurement times of around 29 h, while XRD measurement needs only a few minutes. The determination of density distribution of boards in the thickness direction was the focus of this study. Both approaches visualised well the impact of raw materials and manufacturing processes on the structure of the panels. The density profiles were dependent on the pulp applied for panel production, and the processing conditions were also influential. Air flow resistance correlated with the maximum density measured inside the board. Both XRT and XRD revealed similar trends, which are useful for the characterisation of insulation materials.

  • 20.
    Lindh, Erik L.
    et al.
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Bergenstråhle-Wohlert, Malin
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Terenzi, Camilla
    KTH Royal Institute of Technology, Sweden.
    Salmen, Lennart
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Furo, István
    KTH Royal Institute of Technology, Sweden.
    Non-exchanging hydroxyl groups on the surface of cellulose fibrils: The role of interaction with water2016Ingår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 434, s. 136-142Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The interaction of water with cellulose stages many unresolved questions. Here 2H MAS NMR and IR spectra recorded under carefully selected conditions in 1H-2H exchanged, and re-exchanged, cellulose samples are presented. It is shown here, by a quantitative and robust approach, that only two of the three available hydroxyl groups on the surface of cellulose fibrils are exchanging their hydrogen with the surrounding water molecules. This finding is additionally verified and explained by MD simulations which demonstrate that the 1HO(2) and 1HO(6) hydroxyl groups of the constituting glucose units act as hydrogen-bond donors to water, while the 1HO(3) groups behave exclusively as hydrogen-bond acceptors from water and donate hydrogen to their intra-chain neighbors O(5). We conclude that such a behavior makes the latter hydroxyl group unreactive to hydrogen exchange with water.

  • 21.
    Lindh, Erik L.
    et al.
    RISE - Research Institutes of Sweden, Bioekonomi. RISE., Innventia. KTH Royal Institute of Technology, Sweden .
    Terenzi, Camilla
    KTH Royal Institute of Technology, Sweden .
    Salmen, Lennart
    RISE - Research Institutes of Sweden, Bioekonomi. RISE., Innventia. KTH Royal Institute of Technology, Sweden .
    Furo, Istvan
    KTH Royal Institute of Technology, Sweden .
    Water in cellulose: evidence and identification of immobile and mobile adsorbed phases by 2H MAS NMR2017Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, s. 4360-4369Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The organization of water molecules adsorbed onto cellulose and the supramolecular hydrated structure of microfibril aggregates represents, still today, one of the open and complex questions in the physical chemistry of natural polymers. Here, we investigate by 2H MAS NMR the mobility of water molecules in carefully 2H-exchanged, and thereafter re-dried, microcrystalline cellulose. By subtracting the spectral contribution of deuteroxyls from the spectrum of hydrated cellulose, we demonstrate the existence of two distinct 2H2O spectral populations associated with mobile and immobile water environments, between which the water molecules do not exchange at the NMR observation time scale. We conclude that those two water phases are located at differently-accessible adsorption sites, here assigned to the cellulose surfaces between and within the microfibril aggregates, respectively. The superior performance of 2H MAS NMR encourages further applications of the same method to other complex systems that expose heterogeneous hygroscopic surfaces, like wood cell walls.

  • 22.
    Lindh, Erik
    et al.
    RISE - Research Institutes of Sweden, Bioekonomi. RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Salmen, Lennart
    RISE - Research Institutes of Sweden, Bioekonomi. RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Surface accessibility of cellulose fibrils studied by hydrogena€“deuterium exchange with water2017Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, nr 1, s. 21-33Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A problem with cellulose-based materials is that they are highly influenced by moisture, leading to reduced strength properties with increasing moisture content. By achieving a more detailed understanding of the water–cellulose interactions, the usage of cellulose-based materials could be better optimized. Two different exchange processes of cellulose hydroxyl/deuteroxyl groups have been monitored by transmission FT-IR spectroscopy. By using line-shape-assisted deconvolution of the changing intensities, we have been able to follow the exchange kinetics in a very detailed and controlled manner. The findings reveal a hydrogen exchange that mainly is located at two different kinds of fibril surfaces, where the differences arise from the water accessibility of that specific surface. The slowly accessible regions are proposed to be located between the fibrils inside of the aggregates, and the readily accessible regions are suggested to be at the surfaces of the fibril aggregates. It was also possible to identify the ratio of slowly and readily accessible surfaces, which indicated that the average aggregate of cotton cellulose is built up by approximately three fibrils with an assumed average size of 12 × 12 cellulose chains. Additionally, the experimental setup enabled visualizing and discussing the implications of some of the deviating spectral features that are pronounced when recording FT-IR spectra of deuterium-exchanging cellulose: the insufficient red shift of the stretching vibrations and the vastly decreasing line widths.

  • 23. Mikkonen, Kirsi S
    et al.
    Liljeström, Ville
    Serimaa, Riitva
    Berglund, Lars
    Salmen, Lennart
    RISE., Innventia.
    Tankanen, Maija
    Enzymatic tailoring reveals the effect of arabinoxylan structure on the properties of nanofibrillated cellulose-reinforced films2012Konferensbidrag (Refereegranskat)
  • 24. Mikkonen, K.S.
    et al.
    Stevanic Srndovic, Jasna
    RISE., Innventia.
    Pirkkalainen, K.
    Liljestrom, V.
    Serimaa, R.
    Salmen, Lennart
    RISE., Innventia.
    Tenkanen, M.
    Microfibrillated cellulose reinforced galactoglucomannan and arabinoxylan films2012Konferensbidrag (Refereegranskat)
  • 25.
    Odeberg Glasenapp, Astrid
    et al.
    RISE - Research Institutes of Sweden, Bioekonomi, Papperstillverkning och förpackningar.
    Alfthan, Johan
    RISE - Research Institutes of Sweden, Bioekonomi, Papperstillverkning och förpackningar.
    Salmen, Lennart
    RISE - Research Institutes of Sweden, Bioekonomi, Bioraffinaderi och energi.
    Stevanic Srndovic, Jasna
    RISE - Research Institutes of Sweden, Bioekonomi, Bioraffinaderi och energi.
    Björk, Elisabeth
    RISE - Research Institutes of Sweden, Bioekonomi, Papperstillverkning och förpackningar.
    Holmqvist, Claes
    RISE - Research Institutes of Sweden, Bioekonomi, Papperstillverkning och förpackningar.
    Yang, Li
    RISE - Research Institutes of Sweden, Bioekonomi, Papperstillverkning och förpackningar.
    Berthold, Jesper
    RISE - Research Institutes of Sweden, Bioekonomi, Papperstillverkning och förpackningar.
    Next level of corrugated board research2019Ingår i: 29th IAPRI Symposium on packaging, 2019: Serving society innovative perspectives on packaging, 2019Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

     For the first time in the Bioeconomy research program at RISE, corrugatedboard has an own research area. Research is building around the main driving forcesin the corrugated board value chain like e-commerce, improved box performance anddigital printing. The main weakness of corrugated board, its moisture sensitivity, isalso addressed.These main driving forces and weaknesses of corrugated board are mirrored in thethemes of this large research program area:Fibre sorption and deformation mechanismsFundamental knowledge on the mechanisms behind moisture sorption and deformation on fibre level is developed to increase moisture and creep resistance throughmodification of paper materials. State of the art methods for characterization ofthe fibre ultra- and nano-structure such as Fourier transform infra-red spectroscopy(FTIR), small angle X-ray scattering (SAXS), and wide angle X-ray scattering (WAXS)give new insights on mechanisms and clarify effects of moisture as well as chemicalmodifications.Papermaking for improved base sheetsConcepts that are explored are fibre-based strength additives produced with novelrefining techniques, and modified ZD-profiles in the sheet for better mechanical properties.Box mechanicsMechanical performance of structures such as corrugated board boxes can be predicted through physically based mathematical modelling by taking the behaviour ofthe constituent materials as well as the geometry into account. Appropriate materialmodels for the corrugated board are identified and finite element models for simulation of corrugated board packaging performance are developed.Tool for inkjet printability on corrugatedThere is a genuine need for improved inkjet printability on corrugated materials thanksto rapid development in e-commerce as well as digitalization along the corrugatedvalue chain. Effective measurement methods and knowledge around ink-substrateinteractions are developed to enable board producers and converters to have effective product development and predictable printability on not only liners but also oncorrugated materials.

  • 26.
    Peng, Hui
    et al.
    Research Institute of Wood Industry of Chinese Academy of Forestry, China.
    Salmen, Lennart
    RISE - Research Institutes of Sweden, Bioekonomi, Bioraffinaderi och energi.
    Jiang, Jíali
    Research Institute of Wood Industry of Chinese Academy of Forestry, China.
    Lu, Jianxiong
    Research Institute of Wood Industry of Chinese Academy of Forestry, China.
    Contribution of lignin to the stress transfer in compression wood viewed by tensile FTIR loading2019Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434XArtikel i tidskrift (Refereegranskat)
    Abstract [en]

    To achieve efficient utilization of compression wood (CW), a deeper insight into the molecular interactions is necessary. In particular, the role of lignin in the wood needs to be better understood, especially concerning how lignin contributes to its mechanical properties. For this reason, the properties of CW and normal wood (NW) from Chinese fir (Cunninghamia lanceolata) have been studied on a molecular scale by means of polarized Fourier transform infrared (FTIR) spectroscopy, under both static and dynamic loading conditions. Under static tensile loading, only molecular deformations of cellulose were observed in both CW and NW. No participation of lignin could be detected. In relation to the macroscopic strain, the molecular deformation of the cellulose C-O-C bond was greater in NW than in CW as a reflection of the higher microfibril angle and the lower load taken up by CW. Under dynamic deformation, a larger contribution of the lignin to stress transfer was detected in CW; the molecular deformation of the lignin being highly related to the amplitude of the applied stress. Correlation analysis indicated that there was a direct coupling between lignin and cellulose in CW, but there was no evidence of such a direct coupling in NW. 

  • 27.
    Peng, Hui
    et al.
    Research Institute of Wood Industry of Chinese Academy of Forestry, China.
    Salmen, Lennart
    RISE - Research Institutes of Sweden, Bioekonomi, Bioraffinaderi och energi.
    Stevanic Srndovic, Jasna
    RISE - Research Institutes of Sweden, Bioekonomi, Bioraffinaderi och energi.
    Lu, Jianxiong
    Research Institute of Wood Industry of Chinese Academy of Forestry, China.
    Structural organization of the cell wall polymers in compression wood as revealed by FTIR microspectroscopy2019Ingår i: Planta, ISSN 0032-0935, E-ISSN 1432-2048, Vol. 250, nr 1, s. 163-171Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Glucomannan was more strongly oriented, in line with the orientation of cellulose, than the xylan in both compression wood and normal wood of Chinese fir. Lignin in compression wood was somewhat more oriented in the direction of the cellulose microfibrils than in normal wood.

    The structural organization in compression wood (CW) is quite different from that in normal wood (NW). To shed more light on the structural organization of the polymers in plant cell walls, Fourier Transform Infrared (FTIR) microscopy in transmission mode has been used to compare the S2-dominated mean orientation of wood polymers in CW with that in NW from Chinese fir (Cunninghamia lanceolata). Polarized FTIR measurements revealed that in both CW and NW samples, glucomannan and xylan showed a parallel orientation with respect to the cellulose microfibrils. In both wood samples, the glucomannan showed a much greater degree of orientation than the xylan, indicating that the glucomannan has established a stronger interaction with cellulose than xylan. For the lignin, the absorption peak also indicated an orientation along the direction of the cellulose microfibrils, but this orientation was more pronounced in CW than in NW, indicating that the lignin is affected by the orientation of the cellulose microfibrils more strongly in CW than it is in NW.

  • 28.
    Rahman, Hafizur
    et al.
    SCA R&D Centre, Sweden.
    Lindström, Mikael E.
    KTH Royal Institute of Technology, Sweden.
    Sandström, Peter
    SCA R&D Centre, Sweden.
    Salmen, Lennart
    RISE - Research Institutes of Sweden, Bioekonomi.
    Engstrand, Per
    Mid Sweden University, Sweden.
    The effect of increased pulp yield using additives in the softwood kraft cook on the physical properties of low-grammage handsheets2017Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, nr 2, s. 317-323Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of increasing the pulp yield by the addition of sodium borohydride (NaBH4) or polysulfide (PS) in softwood kraft cooking, i.e. enhancing the retention of glucomannan, on the physical properties of low-grammage handsheets was studied. In addition to the yield improvement, an increase in tensile index was observed, especially at lower degrees of beating. These higher yield pulps showed an increase in pore volume, indicating an increased degree of swelling of the fibres. Presumably, the increased flexibility of the fibres affects the bonding strength and leads to the higher tensile index observed.

  • 29.
    Salmen, Lennart
    RISE., Innventia.
    Role of lignin in the structure of wood fibres2015Ingår i: Proceedings of the 8th Plant Biomechanics International Conference, 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    Wood materials are nowadays being viewed with increasing interest, as a green resource. Its utilization in new types of applications is also highly desired. Thus a better understanding of the wood ultrastructure and how the wood components are interacting in building up its properties is highly demanded. In the wood, the cellulose fibril aggregates dominates properties especially along the grain why the contribution from the other wood polymers and its role in the arrangement of the cell wall structure is often neglected. However their importance both in affecting transverse fiber properties and in their role as a spacer affecting cellulose aggregation during processing cannot be neglected. As the cellulose microfibrils make up a highly irregular lenticular three-dimensional structure the role of the matrix polymers in-between may be viewed in different ways. The understanding of the load bearing capacities of the lignin in different structural elements may be a key factor.

  • 30.
    Salmen, Lennart
    RISE - Research Institutes of Sweden, Bioekonomi, Bioraffinaderi och energi.
    Wood cell wall structure and organisation in relation to mechanics2018Ingår i: Plant Biomechanics: From structure to function at multiple scales, Springer International Publishing , 2018, s. 3-19Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    The wood cell wall, as well as the entire wood structure, is a highly intermixed assembly of biopolymers building up various structural elements. The understanding of the organisation of these wood polymers and their interaction is a key to be able to better utilise wood materials. The complexity of the wood cell wall is here discussed regarding the cellulose fibrillar network, the cellulose aggregate structure and the arrangement of the matrix polymers of hemicelluloses and lignin. The ability to model the wood cell wall properties, based on the structural organisation within different cell wall structures, and the difficulties in relating predictions to actual measurements of cell wall properties are described. The deficiencies regarding our structural knowledge in relation to mechanical properties are also being defined.

  • 31.
    Salmen, Lennart
    RISE., Innventia.
    Wood morphology and properties from molecular perspectives2015Ingår i: Annals of Forest Science, ISSN 1286-4560, E-ISSN 1297-966X, Vol. 72, nr 6, s. 679-684Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    • Background

    It is with increasing interest that wood materials are now being considered as a green resource. For improving the product performance of wood derived materials new ways of separating them from wood are required. Thus, there is a great demand for a better understanding of the ultrastructure of wood and how the components are interaction on a molecular level in building up its properties.

    • Material and method

    By the use of microscopic and spectroscopic techniques combined with mechanical forces, new knowledge regarding especially the role of the matrix polymers, the hemicelluloses and lignin, has been gained. This relates specifically to molecular interaction and orientation.

    • Results

    It is here demonstrated that all of the wood polymers within the secondary cell wall exhibit a preferred orientation along the fibrils. The degree of orientation decreases in the order cellulose, hemicelluloses to the lignin which only shows a small degree of orientation, probably induced by structural constrains.

    • Conclusion

    This orientation distribution is probably what has to be considered to better predict transverse cell wall properties. Moisture accessible regions are also aligned in a parallel arrangement in the cellulose fibrils explaining its high moisture resistance. The lignin is surprisingly inactive in the stress transfer in the secondary wall. This could perhaps be related to the function of lignin providing compressive, hydrostatic resistance in the lenticular spaces between fibrils, when longitudinally straining the fibre. This knowledge of the ultrastructural properties of the wood polymers, here presented, provides for a better understanding of the cell wall properties.

  • 32.
    Salmen, Lennart
    et al.
    RISE., Innventia.
    Axegård, Peter
    RISE., Innventia.
    Utilization of the wood fibre for biorefinery products2014Konferensbidrag (Refereegranskat)
  • 33.
    Salmen, Lennart
    et al.
    RISE., Innventia.
    Bergnor, Elisabeth
    RISE., Innventia.
    Olsson, Anne-Mari
    RISE., Innventia.
    Åkerström, Mårten
    RISE., Innventia.
    Uhlin, Anders
    RISE., Innventia.
    Extrusion of Softwood Kraft Lignins as Precursors for Carbon Fibres2015Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 10, nr 4, artikel-id 7544Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There is much interest in using less expensive raw materials as precursors for carbon fibre manufacture to increase the utilisation of strong, light-weight composite materials in the transportation sector. One such potential raw material is lignin. Most studies exploring melt spinning of lignin have used lignins from organosolv or hardwood kraft delignification processes. There has been little success reported in utilisation of the more commercially available softwood kraft lignins. In this study, lignins from different softwood kraft cooking processes were investigated with respect to their melt spinning performance and conversion to carbon fibres. The isolated lignins differed mainly in molecular weight, glass transition temperature, and softening temperature. All of the lignins produced from the laboratory cooks could be extruded without any plasticizer addition. However, the lignins contained volatiles that resulted in bubbles being formed along the length of the fibres. After vacuum drying, at elevated temperatures to remove volatiles, only the lignin originating from conventional kraft cooking was able to be melt extruded without plasticiser addition; this lignin had the lowest molecular weight amongst the samples. The stabilisation and carbonisation of these fibres gave carbon fibres with strengths comparable to those produced from lignins of other origins.

  • 34.
    Salmen, Lennart
    et al.
    RISE., Innventia.
    Bergström, E.
    RISE., Innventia.
    Cellulose structural arrangement in relation to spectral changes in tensile loading FTIR2009Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 16, nr 6, s. 975-982Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to utilise wood and wood fibres in advanced materials, a better understanding of the mechanical material characteristics and the interactions among the components is necessary. For this purpose, FTIR was explored together with mechanical loading as a means of studying the molecular responses to the loading of spruce wood and cellulose paper material. A linear shift of absorption bands was detected as the loading was applied. In relation to the applied stress these shifts were higher under moist conditions than under dry ones but they were similar with regard to the strains applied. There were no shifts detected in bands related to lignin or the hemicelluloses. The results are interpreted as reflecting a parallel arrangement of the load bearing component, the cellulose ordered structure, and the moisture accessible regions in the cellulose microfibril structure. This therefore represents an equal strain loaded system.

  • 35.
    Salmen, Lennart
    et al.
    RISE., Innventia.
    Burgert, I.
    Cell wall features with regard to mechanical performance. A review.: COST Action E35 2004-2008 : Wood machining - Micromechanics and fracture2009Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 63, nr 2, s. 121-129Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The mechanical performance of wood and wood products is highly dependent on the structural arrangement and properties of the polymers within the fibre cell wall. To improve utilisation and manufacture of wood materials, there is an increasing need for a more detailed knowledge regarding structure/property relations at the micro- or nanostructural level. In this article, recent developments regarding our understanding of the wood cell wall structure and its mechanical performance are summarised. The new results are interpreted in relation to property performances of wood fibres and wood tissues. Suggestions are made for future requirements for research in this field. © 2009 by Walter de Gruyter.

  • 36.
    Salmen, Lennart
    et al.
    RISE - Research Institutes of Sweden, Bioekonomi, Bioraffinaderi och energi.
    Larsson, Per A
    KTH Royal Institute of Technology, Sweden.
    On the origin of sorption hysteresis in cellulosic materials2018Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 182, s. 15-20Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Moisture sorption and moisture sorption hysteresis of carbohydrates are phenomena which affect the utilisation of products made thereof. Although extensively studied, there is still no consensus regarding the mechanisms behind sorption hysteresis. Attempts have been made to link the behaviour to molecular properties, in particular to softening properties, and the moisture sorption hysteresis has therefore here been investigated by modifying cellulosic fibres to affect their softening properties. The results show that the moisture sorption hysteresis diminishes with decreasing softening temperature, and was even completely absent at the higher degrees of modification. The moisture sorption characteristics also changed from a type II sorption to a more type III sorption behaviour, a feature more prominent the higher the degree of modification and the higher the temperature. For the highest degree of modification studied the sorption characteristics changed from sorbing less water the higher the temperature to sorbing more water with increasing temperature.

  • 37.
    Salmen, Lennart
    et al.
    RISE., Innventia.
    Lindström, Mikael
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Improved pulp yield and strength by retained glucomannans in kraft pulping of softwood2015Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 30, nr 4, s. 584-590Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The possibilities of improving yield and strength properties of softwood bleached kraft pulps by retaining a higher content of glucomannan during kraft cooking using additives that decrease the rate of carbohydrate degradation were looked upon. In addition the effect of an increased alkaline concentration, favouring stopping reactions over peeling reactions was explored. Yield increases in the range of 2 to 4%-units were achieved using additives. In the case of the higher alkali charge instead a small yield decrease was noticed. Higher alkali charge in general resulted in a larger loss of xylan in the pulp. When examining the effects of the application of shearing forces at the end of the cook, mimicking industrial pulps, all cooks using high alkali conditions were affected by a large decrease in strength properties, both in tensile index and tear index as well as in fibre strength measured as re-wet Zero-span. For pulps cooked with polysulphide and H2S additions, stabilising the glucomannan degradation, the strength reductions were smaller than for the reference pulps. This resulted in pulps with both a higher yield and similar or better strength properties than those for the reference pulp. These pulps also had better beatability, i.e. the tensile strength increased faster during PFI-beating than for the reference pulp.

  • 38.
    Salmen, Lennart
    et al.
    RISE., Innventia.
    Olsson, Anne-Mari
    RISE., Innventia.
    Physical properties of cellulosic materials related to moisture changes2016Ingår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 50, nr 1, s. 81-89Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Moisture affects the mechanical properties of paper to a high degree. Moreover, the creep properties of paper may be highly affected while the relative humidity is changing, exhibiting mechano-sorptive creep. The reasons for the great sensitivity to moisture changes of papers are not fully explained. In this study, thin papers were examined during sorption processes and the moisture content within the paper, paper length and dynamic elastic modulus during RH changes were measured. It is demonstrated that the dimensional changes of the paper exactly reflected the changes in moisture content within the sample. During both absorption and desorption, the elastic modulus changed so that it was lower than the equilibrium value corresponding to its moisture content. This was especially evident during absorption where the modulus dropped below the equilibrium value at the end RH, i.e. the value was approached from below. The modulus drop was highly related to RH changes made at higher RH and could possibly be related to the softening of carbohydrates.

  • 39.
    Salmen, Lennart
    et al.
    RISE., STFI-Packforsk.
    Possler, H.
    Stevanic, Jasna S.
    RISE., STFI-Packforsk.
    Stanzl-Tschegg, S. E.
    Analysis of thermally treated wood samples using dynamic FT-IR-spectroscopy2008Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 62, nr 6, s. 676-678Artikel i tidskrift (Refereegranskat)
  • 40.
    Salmen, Lennart
    et al.
    RISE - Research Institutes of Sweden, Bioekonomi, Bioraffinaderi och energi.
    Stevanic Srndovic, Jasna
    Effect of drying conditions on cellulose microfibril aggregation and "€œhornification"2018Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, nr 11, s. 6333-6344Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Drying of chemical pulps results in a decreased swelling of the fibres, leading to lower density and strength properties of paper sheets. To investigate how variation of pulp pH, drying process temperature, and final moisture content affect this phenomenon, structural studies were performed on a cellulose-rich pulp. Interrupting the drying at moisture contents of around 20%, using drying temperatures of 80 °C and 140 °C, resulted in a more severe degree of hornification than if the pulp was completely dried at the same temperatures. This increased loss of swelling was accompanied by increased cellulose microfibril aggregation. No change of the cellulose microfibril size or of the cellulose crystallinity, as determined by NMR, could be seen. Further, the accessibility of the cellulose microfibril surfaces, including surfaces between microfibrils, was unaffected by the drying. Thus, hornification should not primarily be related to a reduction of accessible cellulosic surfaces.

  • 41.
    Salmen, Lennart
    et al.
    RISE., Innventia.
    Stevanic Srndovic, Jasna
    RISE., Innventia.
    Olsson, Anne-Mari
    RISE., Innventia.
    Contribution of lignin to the strength properties in wood fibres studied by dynamic FTIR spectroscopy and dynamic mechanical analysis (DMA)2016Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 70, nr 12, s. 1155-1163Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A deeper insight into the molecular interactions in the highly intermixed structure of the wood cell wall, from the point of view of both basic and applied science, is necessary. In particular, the role of the different matrix materials within the cell wall needs to be better understood, especially concerning how lignin contributes to the mechanical properties. In the present paper, the mechanical properties of spruce wood have been studied on a molecular scale by means of dynamic Fourier transform infrared (FTIR) spectroscopy. To this purpose, native spruce wood was subjected to chemical changes by impregnation and a mild pre-cooking with white liquor with a composition usual for kraft pulping. For comparison, lignin-rich primary cell wall material was also isolated by means of thermomechanical pulp (TMP) refining. Dynamic FTIR spectroscopy revealed that lignin took part in the stress transfer in all investigated samples. This finding is in contrast to literature data. A strong indirect coupling between lignin and cellulose was seen in the primary cell wall (P) material. In case of native wood, the lignin signal was much weaker and also indicated an indirect coupling to cellulose. In the case of pre-cooked wood samples (submitted to mild pulping), the interactions were modified so that the molecular straining of lignin was stronger and more directly related to that of cellulose. In other words, in these samples, lignin played a more active role in the stress transfer as compared to native wood. These findings were supported by a narrower lignin-softening region as measured by dynamic mechanical analysis (DMA). The interpretation is plausible in terms of the superior stiffness seen for high-yield pulps of a similar yield as the studied pre-cooked wood samples.

  • 42.
    Stevanic, Jasna S.
    et al.
    RISE., STFI-Packforsk.
    Salmen, Lennart
    RISE., STFI-Packforsk.
    Characterizing wood polymers in the primary cell wall of Norway spruce (Picea abies (L.) Karst.) using dynamic FT-IR spectroscopy2008Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 15, nr 2, s. 285-295Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dynamic Fourier Transform Infra-Red (FT-IR) spectroscopy was used to examine the interactions among cellulose, xyloglucan, pectin, protein and lignin in the outer fibre wall layers of spruce wood tracheids. Knowledge regarding these interactions is fundamental for understanding the fibre separation in a mechanical pulping process. Sheets made from an enriched primary cell wall material were used for studying the viscoelastic response of the polymers. The results indicated that strong interactions exist among lignin, protein, pectin, xyloglucan and cellulose in the primary cell wall. This signified a closely linked network structure of the components on the fibre surface. This ultrastructural arrangement in the primary cell wall and the relatively high content of lignin, pectin and protein in it, means that the primary cell wall is more submissive to selective chemical attacks, when compared to the secondary cell wall. A low ratio of cellulose Iα to cellulose Iβ in the primary cell wall was also found.

  • 43.
    Stevanic, Jasna S.
    et al.
    RISE., STFI-Packforsk.
    Salmen, Lennart
    RISE., STFI-Packforsk.
    Interactions among components in the primary cell wall of Norway spruce (Picea Abies (L.) Karst.): Effect of a low sulphonation pretreatment2008Ingår i: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 34, nr 2, s. 107-112Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dynamic Fourier Transform Infra-Red (FT-IR) spectroscopy was used to examine the effect of a low sulphonation treatment on the ultrastructure of the primary cell wall of spruce wood. Sheets made from enriched primary cell wall material coming from a low sulphonated thermomechanical pulp were used for studying the viscoelastic response of the polymers using dynamic FT-IR spectroscopy. The overall ultrastructure of the primary cell wall remained largely unaltered, due to the exceptionally low degree of sulphonation used. However, an increased softening of the material as well as a weakening of the lignin;pectin, lignin;protein and pectin;protein interactions were observed. The suggestion is that, together with a structural modification of the lignin, it is the increased viscoelasticity of the material, resulting from the breaking down of the interactions among the polymers, that is the cause for the lower energy demand, when refining correspondingly low sulphonated chips.

  • 44.
    Stevanic, Jasna S.
    et al.
    RISE., STFI-Packforsk.
    Salmen, Lennart
    RISE., STFI-Packforsk.
    Orientation of the wood polymers in the cell wall of spruce wood fibres2009Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 63, nr 5, s. 497-503Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The mechanical and physical properties of wood fibres depend to a large extent on the orientation of the polymers, mainly the cellulose microfibrils, within the supramolecular structure of the cell wall. Under moist conditions, the arrangement within the polymer matrix may play a dominant role for mechanical properties in general and, especially, in the transverse direction. In this context, it is of special interest to determine the orientation of glucomannan and xylan, being the essential components of softwood hemicelluloses, and of lignin in wood fibres. Fourier transform infrared (FTIR) microscopy was used to examine the orientation of the main wood polymers in transversal and longitudinal direction of spruce fibres. We investigated fibres made from a thermomechanical pulp, in which the outer fibre wall layers were removed by mechanical action, and chemically delignified fibres. The polarised FTIR measurements indicated that glucomannan and xylan appear to have a parallel orientation with regard to the orientation of cellulose and, in all probability, an almost parallel orientation with regard to the fibre axis. Lignin was found to be less oriented in the fibre wall, although its arrangement is not fully isotropic. In the longitudinal direction of the fibres, there were no significant changes in the molecular orientation of the studied polymers.

  • 45.
    Veguta, Vijaya Lakshmi
    et al.
    RISE - Research Institutes of Sweden, Bioekonomi. RISE., Innventia. KTH Royal institute of technology, Sweden.
    Stevanic, Jasna S.
    RISE - Research Institutes of Sweden, Bioekonomi. RISE., Innventia.
    Lindström, Mikael E.
    KTH Royal institute of technology, Sweden.
    Salmen, Lennart
    RISE - Research Institutes of Sweden, Bioekonomi. RISE., Innventia.
    Thermal and alkali stability of sodium dithionite studied using ATR-FTIR spectroscopy2017Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, nr 2, s. 2496-2506Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sodium dithionite (Na2S2O4) may have the potential to be used as a reducing agent for the stabilization of glucomannan in kraft cooking for increased pulp yield. However, due to the fact that dithionite decomposes under the conditions of kraft pulping, studies of the effects of dithionite in kraft pulping are non-conclusive; sometimes clearly showing an increased yield, and in other studies no effect at all. The specific conditions influencing dithionite degradation are also unclear. For that reason, this study was conducted to determine the thermal and chemical stability of sodium dithionite with respect to specific factors, such as the pH, temperature, heating time, and the concentration of sodium dithionite solution. The study was performed under anaerobic conditions using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The thermal and alkali stability of the sodium dithionite solution was shown to decrease with increasing temperature, heating time, and concentration of the solution at the alkaline conditions studied. The thermal stability decreased rapidly at weak alkalinity (pH 9) as well as in high alkalinity (pH 14), whereas the sodium dithionite was rather stable at moderate alkalinity (pH 11.5 to pH 13).

  • 46.
    Viforr, Silvia
    et al.
    RISE., STFI-Packforsk.
    Salmen, Lennart
    RISE., STFI-Packforsk.
    Shear/compression of chips for lower energy consumption in TMP refining2008Ingår i: Appita journal, ISSN 1038-6807, Vol. 61, nr 1, s. 49-55Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fundamental studies of the deformation behaviour of wood show that combining small amounts of shear along with compression within a roll press reduces the work required for cell wall deformation. This permanent deformation can be increased by: increased number of passes through the nip reduced roll speed increased process temperature. Refining trials showed that the strength properties (except for the tear index), as well as the optical properties of TMP produced from these shear/compression pretreated chips are improved, with the potential of reducing electric energy by approx. 100 kWh/tonne, when compared to untreated chips.

  • 47. Yin, Yafang
    et al.
    Berglund, Lars
    Salmen, Lennart
    RISE., Innventia.
    Effect of compressive treatment by steaming on the properties of wood cell walls2011Konferensbidrag (Refereegranskat)
1 - 47 av 47
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
v. 2.35.8