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  • 1.
    Aldaeus, F.
    et al.
    RISE, Innventia.
    Schweinebarth, H.
    RISE, Innventia.
    Törngren, P.
    RISE, Innventia.
    Jacobs, A.
    RISE, Innventia.
    Simplified determination of total lignin content in kraft lignin samples and black liquors2011In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, no 4, p. 601-604Article in journal (Refereed)
  • 2. Alfredsen, G.
    et al.
    Pilgard, A.
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Fossdal, C. G.
    Characterisation of Postia placenta colonisation during 36 weeks in acetylated southern yellow pine sapwood at three acetylation levels including genomic DNA and gene expression quantification of the fungus2016In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 70, no 11, p. 1055-1065Article in journal (Refereed)
    Abstract [en]

    One way to protect timber in service against basidiomycete deterioration is by means of acetylation via reaction with acetic anhydride. The reason why acetylated wood (WAc) is resistant against decay fungi is still not exactly understood. The aim of this study was to contribute to this field of science, and Postia placenta colonisation after 4, 12, 20, 28 and 36 weeks was observed at three acetylation levels of Pinus spp. sapwood. Mass loss (ML) and wood moisture content (MC) data reflected the acetylation levels. The initial equilibrium MC (EMC) proved to be a good indicator of subsequent ML. Genomic DNA quantification showed P. placenta colonisation in all samples, also in samples where no ML were detectable. The number of expressed gene transcripts was limited, but the findings supported the results of previous studies: WAc seems to have some resistance against oxidative mechanisms, which are part of the metabolism of P. placenta. This leads to a delay in decay initiation, a delay in expression of genes involved in enzymatic depolymerisation, and a slower decay rate. The magnitudes of these effects are presented for each acetylation level. The data also imply that there is no absolute decay threshold at high acetylation levels, but instead a significant delay of decay initiation and a slower decay rate. © 2016 Walter de Gruyter GmbH, Berlin/Boston.

  • 3. Ambjörnsson, H.A.
    et al.
    Östberg, L.
    Schenzel, K.
    Larsson, P.T.
    RISE, Innventia.
    Germgård, U.
    Enzyme pretreatment of dissolving pulp as a way to improve the following dissolution in NaOH/ZnO2014In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 68, no 4, p. 385-391Article in journal (Refereed)
  • 4.
    Bengtsson, Andreas
    et al.
    KTH Royal Institute of Technology, Sweden.
    Bengtsson, Jenny
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Olsson, Carina
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Sedin, Maria
    RISE - Research Institutes of Sweden, Bioeconomy, Papermaking and Packaging.
    Jedvert, Kerstin
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    Sjöholm, Elisabeth
    RISE - Research Institutes of Sweden, Bioeconomy, Biobased Materials.
    Improved yield of carbon fibres from cellulose and kraft lignin2018In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434XArticle in journal (Refereed)
    Abstract [en]

    To meet the demand for carbon-fibre-reinforced composites in lightweight applications, cost-efficient processing and new raw materials are sought for. Cellulose and kraft lignin are each interesting renewables for this purpose due to their high availability. The molecular order of cellulose is an excellent property, as is the high carbon content of lignin. By co-processing cellulose and lignin, the advantages of these macromolecules are synergistic for producing carbon fibre (CF) of commercial grade in high yields. CFs were prepared from precursor fibres (PFs) made from 70:30 blends of softwood kraft lignin (SW-KL) and cellulose by dry-jet wet spinning with the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([EMIm][OAc]) as a solvent. In focus was the impact of the molecular mass of lignin and the type of cellulose source on the CF yield and properties, while membrane-filtrated kraft lignin and cellulose from dissolving kraft pulp and fully bleached paper-grade SW-KP (kraft pulp) served as sources. Under the investigated conditions, the yield increased from around 22% for CF from neat cellulose to about 40% in the presence of lignin, irrespective of the type of SW-KL. The yield increment was also higher relative to the theoretical one for CF made from blends (69%) compared to those made from neat celluloses (48-51%). No difference in the mechanical properties of the produced CF was observed.

  • 5.
    Bengtsson, Charlotte
    et al.
    AB Trätek.
    Kliger, Robert
    Bending creep of high-temperature dried spruce timber2003In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 57, no 1, p. 95-100Article in journal (Refereed)
    Abstract [en]

    In this paper, bending creep test results from high-temperature (HT) dried Norway Spruce timber are presented. The results are compared with creep tests of conventional low-temperature (LT) dried timber. The HT drying was performed at 115°C and the LT drying was performed at 70°C. The creep tests were performed in a varying climate with 20°C and 30–90% relative humidity. A total number of 24 specimens, 45 × 70 × 1100 mm, were loaded in bending during approximately 240 days. Both the HT-dried and the LT-dried material were cut from the same four trees to have as equal raw material as possible for the two drying methods. The results show smaller bending creep deformations of HT-dried timber (approximately 30%) as compared to the LT-dried timber. The variation in magnitude of creep for HT-dried timber was equal to or smaller than for LT-dried timber. Additionally, the variation in deformation between the moisture cycles was smaller for HT-dried timber. These observations indicate a less pronounced mechano-sorptive effect for HT-dried timber. The free shrinkage in the grain direction was significantly smaller for the HT-dried material than for the LT-dried material.

  • 6.
    Brodin, Ida
    et al.
    RISE, Innventia.
    Ernstsson, Marie
    YKI, Stockholm, Sweden.
    Gellerstedt, Göran
    RISE, Innventia.
    Sjöholm, Elisabeth
    RISE, Innventia.
    Oxidative stabilisation of kraft lignin for carbon fibre production2012In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, no 2, p. 141-147Article in journal (Refereed)
  • 7. Brodin, Ida
    et al.
    Sjöholm, Elisabeth
    RISE, STFI-Packforsk.
    Gellerstedt, Göran
    RISE, STFI-Packforsk.
    Kraft lignin as feedstock for chemical products: The effects of membrane filtration2009In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 63, no 3, p. 290-297Article in journal (Refereed)
    Abstract [en]

    The use of technical lignins as feedstock for chemical products will require improvements in purity, molecular mass distribution, and thermal behavior. Therefore, industrial black liquors from kraft pulping of softwood (spruce/pine) and hardwood (birch and Eucalyptus globulus) have been subjected to fractionation according to molecular mass by ceramic membranes. After acidification and isolation of the lignin fractions, a variety of analytical methods have been applied to help understand their structure - property relationships. From all types of lignin, the chemical and polymeric properties of fractions isolated from the membrane permeates were more homogeneous. This demonstrates that technical kraft lignins, irrespective of origin, may constitute an interesting feedstock for products, such as carbon fibers, adhesives, and phenol-based polymers.

  • 8. Bryne, Lars Elof
    et al.
    Lausmaa, Jukka
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Funktionella material (KMf).
    Ernstsson, Marie
    Englund, Finn
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, Trätek.
    Wålinder, Magnus
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, Trätek.
    Ageing of modified wood. Part 2: Determination of surface composition of acetylated, furfurylated, and thermally modified wood by XPS and ToF-SIMS2010In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 64, no 3, p. 305–313-Article in journal (Refereed)
    Abstract [en]

    The main objective of this work was to study the chemical composition of surfaces and ageing effects on acetylated pine (Pinus sylvestris), heat treated spruce (Picea abies), and furfurylated radiata pine (Pinus radiata) in comparison to unmodified wood. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were the instruments of choice. Observation with a low-vacuum scanning electron microscope (LV-SEM) complemented the study. The spectroscopic information was also linked to a parallel wettability study on matched wood samples by the Wilhelmy method. The results show that XPS and ToF-SIMS are two powerful tools that in combination give complementary information, both quantitative and qualitative, and are well suited for observation of the ageing process of different wood surfaces. The hydrophobization process as a result of migration of extractives during ageing was well quantified by the XPS measurements and the results correlated well with wetting results. Several specific hydrophobic substances could be identified by ToF-SIMS measurements.

  • 9. Bryne, Lars Elof
    et al.
    Wålinder, Magnus
    SP- Sveriges Tekniska Forskningsinstitut, Trätek.
    Ageing of modified wood. Part 1: Wetting properties of acetylated, furfurylated, and thermally modified wood2010In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 64, no 3, p. 295–304-Article in journal (Refereed)
    Abstract [en]

    The main objective of this work was to apply contact angle analysis to predict work of adhesion (Wa) between some modified wood materials and certain thermoplastics and adhesives. Wetting properties, i.e., contact angles, were measured by the Wilhelmy method on both freshly prepared and aged veneer samples of unmodified and acetylated Scots pine, furfurylated radiata pine, and heat treated Norway spruce. The sessile drop method was used to measure contact angles on a phenol resorcinol formaldehyde, an emulsion polymer isocyanate, and a one-component polyurethane adhesive. Contact angle data were also collected from the literature on polyethylene, polyvinyl chloride, polymethyl methacrylate, polystyrene, and Nylon 6. Contact angle analysis based on the Chang-Qin-Chen model was then applied to determine so-called acid-base interaction parameters and Wa between the wood samples and the selected thermoplastics and adhesives. Results show that the ageing process led to an increased hydrophobic character of unmodified, heat treated, and furfurylated wood samples. The freshly prepared acetylated wood samples had a pronounced hydrophobic character which remained approximately constant after ageing. The predicted Wa between the wood and the adhesives was considerably higher than that between the wood and the thermoplastics. Furthermore, the predicted Wa between the acetylated wood and both the thermoplastics and water was approximately unchanged when comparing the fresh and aged samples. In contrast, the ageing of all other wood samples resulted in a dramatic decrease of the wood-water Wa and a moderate decrease of the wood-thermoplastics Wa. The wood-adhesives Wa, however, was unchanged for the unmodified and furfurylated wood when comparing the fresh and aged samples and even increased for heat treated and acetylated wood samples.

  • 10.
    Brännvall, Elisabet
    RISE - Research Institutes of Sweden, Bioeconomy, Biorefinery and Energy.
    Increasing pulp yield in kraft cooking of softwoods by high initial effective alkali concentration (HIEAC) during impregnation leading to decreasing secondary peeling of cellulose2018In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434XArticle in journal (Refereed)
    Abstract [en]

    Pulp yield can be improved by a more homogeneous delignification of the chips, achieved by improved impregnation prior to the cooking stage. Complete and efficient impregnation is obtained by increasing the diffusion rate by means of an impregnation liquor with a high initial effective alkali concentration (HIEAC). In the present study, the effect of HIEAC in the impregnation was evaluated and compared to a reference impregnation procedure and a prolonged impregnation. After the various impregnation scenarios, the alkali concentration was always adjusted to the same level in the beginning of the cooking stage. Impregnation with a HIEAC resulted in yield improvements by 1-1.5% units, due to a higher cellulose yield and possibly also to higher yield of glucomannan. The HIEAC with an even alkali distribution within the chips prior to the cooking stage resulted in a more uniform delignification carbohydrate degradation. Yield increase obtained by uniform delignification is due to both decreased shives content as well as less secondary peeling.

  • 11.
    Brännvall, Elisabet
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, Biorefinery and Energy.
    Reimann, Anders
    RISE - Research Institutes of Sweden, Bioeconomy, Biobased Materials.
    The balance between alkali diffusion and alkali consuming reactions during impregnation of softwood. Impregnation for kraft pulping revisited2018In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, no 3, p. 169-178Article in journal (Refereed)
    Abstract [en]

    The purpose of the impregnation stage is to ensure that cooking chemicals reach all parts of the chips. However, as alkali comes into contact with wood, reactions take place, which alter the paths available for ionic transport and dissolve wood components. The aim of the present study is to establish the most favorable impregnation conditions, which result in an even alkali concentration profile through the chip at a sufficiently high level without extensive yield losses due to peeling. Softwood chips were subjected to different impregnation conditions. The progress of impregnation was assessed by analyzing the concentration of hydroxide ions in the bound liquor inside wood chips and the release of acetic acid. The extent of undesired reactions was measured as the amount of carbohydrate degradation products formed and amount of wood dissolved. Increased temperature and time lead to more degradation of the carbohydrates during impregnation. At high temperature, the concentration of alkali in the bound liquor was lower due to higher alkali consumption in degradation reactions. The most favorable process is to perform impregnation at an elevated initial effective alkali (EA) for a short time. This resulted in an increased alkali concentration in the bound liquor within the chip without extensive carbohydrate degradation.

  • 12. Buchert, J
    et al.
    Carlsson, G
    YKI – Ytkemiska institutet.
    Viikari, L
    Ström, G
    Surface characterization of unbleached kraft pulps by enzymatic peeling and ESCA1996In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 50, p. 69-74Article in journal (Refereed)
    Abstract [en]

    Specific enzymes hydrolyzing pulp carbohydrates can be used for characterization of pulp fibres. By combining enzymatic peeling of fibre hemicelluloses with novel techniques of surface analysis, such as ESCA, new information can be obtained on the location of different components, i.e. xylan, glucomannan and lignin on the fibre surfaces. In this work unbleached kraft pulps were selectively peeled with purified Trichoderna reesi xylanase and mannanase and the structural modifications caused by the removal of the hemicelluloses were analyzed with ESCA. The removal of the accessible portion of the pine kraft xylan increased the amount of surface lignin, whereas mannan removal had no effect on the amount of lignin on the surface. In the case of birch kraft pulp the removal of accessible xylan did not enhance the amount of lignin on the surface. However, in birch kraft pulp the removal of xylan decreased the amount of extractives covering the surface.

  • 13.
    Bäckström, Marie
    et al.
    RISE, Innventia.
    Jensen, Anna
    RISE, Innventia.
    Brännvall, Elisabet
    RISE, Innventia.
    Influence of chip presteaming conditions on kraft pulp composition and properties2016In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 70, no 5, p. 393-399Article in journal (Refereed)
    Abstract [en]

    Presteaming is a well-established technique in pulp mills, which improves cooking liquor impregnation by removing air from within and between chips. The aim of the study was to investigate how conditions during steaming affect the subsequent kraft cook and properties of the obtained pulp. It was found that higher pressure and temperature during chip presteaming led to increased degradation and dissolution of hemicelluloses. Lower refinability and tensile index was obtained for pulps cooked after presteaming at high pressure and for a long time.

  • 14.
    Bäckström, Marie
    et al.
    RISE, STFI-Packforsk.
    Kolar, Marie-Claude
    RISE, STFI-Packforsk.
    Htun, Myat
    RISE, STFI-Packforsk.
    Characterisation of fines from unbleached kraft pulps and their impact on sheet properties2008In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 62, no 5, p. 546-552Article in journal (Refereed)
    Abstract [en]

    Fines are an essential component in the papermaking process because they have a profound influence on the behaviour of the wet web and on the mechanical properties of the final sheet. Primary fines are present in the pulp prior to refining, and secondary fines are produced during refining. In the present investigation, two commercially manufactured unbleached pulps with kappa numbers of 45 and 90 were studied in terms of how they responded to refining with respect to the quality of fibre and fines. Primary and secondary fines were collected and characterised and their impact on sheet strength was evaluated by addition of known amounts to a refined and decrilled pulp. All the measured paper strength properties improved when primary and secondary fines were added. The strength improvement was generally somewhat higher in the second case. The effect was more pronounced at a higher level of addition. We attribute the main strength improvements associated with fines to improved consolidation by the creation of capillary forces between the surfaces.

  • 15. Chen, Z. -Q
    et al.
    Abramowicz, K.
    Raczkowski, R.
    Ganea, S.
    Wu, H. X.
    Lundqvist, Sven-Olof
    RISE, Innventia.
    Mörling, T.
    De Luna, S. S.
    Garci­a Gil, M. R.
    Mellerowicz, E. J.
    Method for accurate fiber length determination from increment cores for large-scale population analyses in Norway spruce2016In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 70, no 9, p. 829-838Article in journal (Refereed)
    Abstract [en]

    Fiber (tracheid) length is an important trait targeted for genetic and silvicultural improvement. Such studies require large-scale non-destructive sampling, and accurate length determination. The standard procedure for non-destructive sampling is to collect increment cores, singularize their cells by maceration, measure them with optical analyzer and apply various corrections to suppress influence of non-fiber particles and cut fibers, as fibers are cut by the corer. The recently developed expectation-maximization method (EM) not only addresses the problem of non-fibers and cut fibers, but also corrects for the sampling bias. Here, the performance of the EM method has been evaluated by comparing it with length-weighing and squared length-weighing, both implemented in fiber analyzers, and with microscopy data for intact fibers, corrected for sampling bias, as the reference. This was done for 12-mm increment cores from 16 Norway spruce (Picea abies (L.) Karst) trees on fibers from rings 8-11 (counted from pith), representing juvenile wood of interest in breeding programs. The EM-estimates provided mean-fiber-lengths with bias of only +2.7% and low scatter. Length-weighing and length2-weighing gave biases of-7.3% and +9.3%, respectively, and larger scatter. The suggested EM approach constitutes a more accurate non-destructive method for fiber length (FL) determination, expected to be applicable also to other conifers.

  • 16. Chunilall, V.
    et al.
    Bush, T.
    Larsson, Per Tomas
    RISE, Innventia.
    Iversen, Tommy
    RISE, Innventia.
    Kindness, A.
    A CP/MAS 13C-NMR study of cellulose fibril aggregation in eucalyptus dissolving pulps during drying and the correlation between aggregate dimensions and chemical reactivity2010In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 64, no 6, p. 693-698Article in journal (Refereed)
    Abstract [en]

    Changes in supramolecular properties of cellulose I, namely its lateral fibril aggregate dimension (LFAD), in bleached hardwood acid bisulphite pulp during drying was studied using cross-polarization/magic angle spinning carbon-13 nuclear magnetic resonance (CP/MAS 13C-NMR) in combination with spectral fitting. A significant change in aggregate dimensions was noticed when each of the pulp grades were oven dried. The effect of drying was further investigated with pulp samples subjected to different drying methods. A comparison of a harsh oven drying, mild and rapid air drying, and a very mild and slow condition drying showed that the LFAD of the material decreases in the following order: oven drying > air drying > condition drying. The correlation between the total extractable material S10 (%) and LFAD and also the LFAD increment (ΔLFAD in %) are presented and shown to be intimately related. This means that the method of drying influences the size of the fibril aggregate dimensions and depends on the presence of extractable material within the fibre cell wall. Reactivity studies were carried out based on the acetylation of cotton linters and commercial 96α pulp. Results indicate that the initial reaction rate is proportional to the specific surface area of the two cellulose pulp samples. Accordingly, the specific surface area is directly related to initial reactivity of the performed acetylation. We demonstrated that it is possible to control the LFAD and hence specific surface area in laboratory-produced pulps 91α, 92α, and 96α by the drying method. Thus controlling LFAD can probably be one viable route for controlling the initial reactivity of dissolving pulp towards acetylation.

  • 17.
    Dedic, D.
    et al.
    RISE, Innventia.
    Sandberg, T.
    Iversen, T.
    RISE, Innventia.
    Larsson, T.
    RISE, Innventia.
    Ek, M.
    Analysis of lignin and extractives in the oak wood of the 17th century warship Vasa2014In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 68, no 4, p. 419-425Article in journal (Refereed)
  • 18. Dvinskikh, Sergey
    et al.
    Henriksson, Marielle
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, Trätek.
    Berglund, Lars
    Furó, István
    A multinuclear magnetic resonance imaging (MRI) study of wood with adsorbed water: Estimating bound water concentration and local wood density2011In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 65, no 1, p. 103–107-Article in journal (Refereed)
    Abstract [en]

    The interaction between moisture and the macromolecular wood tissue is of critical importance to wood properties. In this context, magnetic resonance imaging (MRI) is very promising as this method could deliver molecular information on the submillimeter scale (i.e., along concentration gradients) about both free and adsorbed water and the cell wall polymers. In the present study, it is demonstrated for the first time that wood containing adsorbed heavy water (2H2O) can be studied by MRI based on separated images due to water (2H MRI) and cell wall polymers (1H MRI). Data confirm that in specimens equilibrated at controlled humidity there is a direct correlation between bound water content and relative density of the polymers in wood tissue; there is a strong variation across annual rings.

  • 19.
    Ehmcke, Gabrielle
    et al.
    Technical University of Munich, Germany.
    Pilgård, Annica
    RISE - Research Institutes of Sweden, Bioeconomy, Biobased Materials. Technical University of Munich, Germany.
    Koch, Gerald
    Thunene Institute of Wood Research, Gemany.
    Richter, Klaus
    Technical University of Munich, Germany.
    Topochemical analyses of furfuryl alcohol-modified radiata pine (Pinus radiata) by UMSP, light microscopy and SEM2017In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 71, no 10, p. 821-831Article in journal (Refereed)
    Abstract [en]

    Furfurylation is one of the wood modification techniques via catalytic polymerization of the monomeric furfuryl alcohol (FA) in the impregnated cell wall. Little is known about the topochemistry of this process. Brown rot degradation begins with lignin modification and therefore, the reactions between FA and lignin was one focus of this research. Furfurylated radiata pine (Pinus radiata) with three different weight percent gains (WPGs of 57%, 60% and 70%) after FA uptake was observed by cellular ultraviolet microspectrophotometry (UMSP) to analyze chemical alterations of the individual cell wall layers. Moreover, light microscopy (LM) and scanning electron microscopy (SEM) analyses were performed. The ultraviolet (UV) absorbance of the modified samples increased significantly compared to the untreated controls, indicating a strong polymerization of the aromatic compounds. Highest UV absorbances were found in areas with the highest lignin concentration. The UMSP images of individual cell wall layers support the hypothesis concerning condensation reactions between lignin and FA.

  • 20. Engelund, E.T.
    et al.
    Salmen, L.
    RISE, Innventia.
    Tensile creep and recovery of Norway spruce influenced by temperature and moisture2012In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, no 8, p. 959-965Article in journal (Refereed)
  • 21. Epmeier, Hanna
    et al.
    Johansson, Marie
    Kliger, Robert
    Westin, Mats
    SP- Sveriges Tekniska Forskningsinstitut, Trätek.
    Material properties and their interrelation in chemically modified clear wood of Scots pine2007In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 61, no 1, p. 34-42Article in journal (Refereed)
  • 22. Epmeier, Hanna
    et al.
    Johansson, Marie
    Kliger, Robert
    Westin, Mats
    SP- Sveriges Tekniska Forskningsinstitut, Trätek.
    Matertial properties and their interrelation in chemically modified clear wood of Scots pine2007In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 61, no 1, p. 34-42Article in journal (Refereed)
  • 23. Fackler, K.
    et al.
    Stevanic, J.S.
    RISE, Innventia.
    Ters, T.
    Hinterstoisser, B.
    Schwanninger, M.
    Salmen, L.
    RISE, Innventia.
    FT-IR imaging microscopy to localise and characterise simultaneous and selective white-rot decay within spruce wood cells2011In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, no 3, p. 411-420Article in journal (Refereed)
  • 24. Fardim, P
    et al.
    Heijnesson Hultén, A
    Boisvert, J-P
    Johansson, L-S
    Ernstsson, M
    YKI – Ytkemiska institutet.
    Campbell, JM
    Critical comparison of methods for surface coverage by extractives and lignin in pulps by X-ray photoelectron spectroscopy (XPS)2006In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 60, p. 149-155Article in journal (Refereed)
    Abstract [en]

    Different methods for estimation of the surface coverage by extractives and lignin were critically compared. For data collection, four state-of-the-art X-ray photoelectron spectroscopy (XPS) instruments located in four different laboratories were used. Hand sheets of one mechanical and two chemical pulp samples were prepared in one laboratory and distributed among the other participants. The XPS results based on O/C ratios and curve fitting of the C 1s peak had very good intra- and interlaboratory variation for extracted and non-extracted pulp samples. The estimations of surface coverage by extractives and lignin also had acceptable intra- and interlaboratory variation. However, significant differences were observed between the results for the various methods. Estimation of surface coverage by extractives based on O/C ratios was much higher than that based on the C1 component analysis in the case of mechanical and unbleached chemical pulp. The surface coverage by lignin of mechanical pulp was reproducibly detected based on O/C ratios, C1 component analysis and by labelling with mercury acetate. The same data were, however, rather scattered if they were collected with these three methods for bleached and unbleached chemical pulp. In spite of the differences, similar trends regarding the pulp type could be observed. We interpret the results as indicating that the surface coverage for both extractives and lignin should not be considered as absolute “true” values, but rather as relative values, which are reliable only for comparison of samples for the same instrument. Even for relative comparisons, we recommend the selection of a strict experimental set-up for spectral acquisition and data treatment when applying any of the instruments and calculation models currently available.

  • 25. Franceschini, T.
    et al.
    Lundqvist, S.-O.
    RISE, Innventia.
    Bontemps, J.-D.
    Grahn, T.
    RISE, Innventia.
    Olsson, L.
    RISE, Innventia.
    Evans, R.
    Leban, J.-M.
    Empirical models for radial and tangential fibre width in tree rings of Norway spruce in north-western Europe2012In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, no 2, p. 219-230Article in journal (Refereed)
  • 26. Gebremeskel, G.G.
    et al.
    Aldaeus, F.
    RISE, Innventia.
    Determination of lignin content in kraft black liquors by capillary zone electrophoresis (CZE)2013In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, no 8, p. 887-890Article in journal (Refereed)
  • 27.
    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, Bioeconomy. RISE, Innventia.
    Yin, Yafang
    Chinese Academy of Forestry, China.
    Effects of thermo-hygro-mechanical (THM) treatment on the viscoelasticity of in-situ lignin2017In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 71, no 6, p. 455-460Article in journal (Refereed)
    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.

  • 28. Heijnesson Hultén, A
    et al.
    Basta, J
    Larsson, P
    Ernstsson, M
    YKI – Ytkemiska institutet.
    Comparison of different XPS methods for fiber surface analysis2006In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 60, no 1, p. 14-19Article in journal (Refereed)
    Abstract [en]

    Three different XPS methods based on the O/C atomic ratio, C1 carbon content, and Hg amount are compared in this study to quantify the surface coverage of various pulp fiber surfaces by lignin and extractives. The sensitivity of the methods to drying technique and the stability of organically bound mercury when subjected to X-ray irradiation were also investigated. Results reveal that the surfaces of all pulp fibers have a higher content of lignin and extractives than the bulk of the fibers. Similar lignin surface coverage was obtained for thermomechanical pulp fibers using the Hg, O/C, and C1 carbon methods, while the Hg method gave lower values for kraft pulp fibers than the O/C and C1 carbon methods. The O/C and C1 carbon methods are sensitive to the drying technique, i.e., air-dried samples showed a higher amount of lignin on the fiber surface than freeze-dried samples, while no or only minor differences in results were obtained using the Hg method. The Hg method was more reproducible than the other methods. Special care must be exercised during XPS analysis to minimize mercury degradation.

  • 29. Jääskeläinen, A-S
    et al.
    Saariaho, A-M
    Vyörykkä, J
    YKI – Ytkemiska institutet.
    Vuorinen, T
    Matousek, P
    Parker, AW
    Application of UV-Vis and resonance Raman spectroscopy to study bleaching and photoyellowing of thermomechanical pulps2006In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 60, p. 231-238Article in journal (Refereed)
    Abstract [en]

    The chemistry of thermomechanical pulp bleaching and brightness reversion was studied. First, UV-Vis reflectance spectroscopy was used to obtain information on the reactive structures in pulp. Based on these data, a Raman excitation wavelength was chosen close to the absorption bands of the chromophores formed to take advantage of the resonance enhancement (resonance Raman spectroscopy). Fluorescence was rejected with a picosecond Kerr gate. The results revealed that coniferyl aldehyde structures were partly removed by alkaline peroxide bleaching and these structures were further degraded during light exposure. However, this reaction was obviously not responsible for chromophore formation in the pulp. On the other hand, based on the resonance Raman spectra, formation of quinonoid structures, possibly para-quinones, was a more prominent explanation for the brightness reversion

  • 30. Kihlman, M.
    et al.
    Aldaeus, F.
    RISE, Innventia.
    Chedid, F.
    RISE, Innventia.
    Germgård, U.
    Effect of various pulp properties on the solubility of cellulose in sodium hydroxide solutions2012In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, no 5, p. 601-606Article in journal (Refereed)
  • 31. Kliger, Robert
    et al.
    Bengtsson, Charlotte
    SP - Sveriges provnings- och forskningsinstitut, Trätek.
    Johansson, Marie
    Comparison between HT-dried and LT-dried spruce timber in terms of shape and dimensional stability2005In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 59, no 6, p. 647-653Article in journal (Refereed)
  • 32.
    Källbom, Susanna
    et al.
    KTH Royal Institute of Technology, Sweden.
    Sedighi Moghaddam, Maziar
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Wålinder, Magnus E. P.
    KTH Royal Institute of Technology, Sweden.
    Liquid sorption, swelling and surface energy properties of unmodified and thermally modified Scots pine heartwood after extraction2018In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, no 3Article in journal (Refereed)
    Abstract [en]

    The effect of extractives removal on liquid sorption, swelling and surface energy properties of unmodified wood (UW) and thermally modified Scots pine heartwood (hW) (TMW) was studied. The extraction was performed by a Soxtec procedure with a series of solvents and the results were observed by the multicycle Wilhelmy plate method, inverse gas chromatography (IGC) and Fourier transform infrared (FTIR) spectroscopy. A significantly lower rate of water uptake was found for the extracted UW, compared with the unextracted one. This is due to a contamination effect in the latter case from water-soluble extractives increasing the capillary flow into the wood voids, proven by the decreased water surface tension. The swelling in water increased after extraction 1.7 and 3 times in the cases of UW and TMW, respectively. The dispersive part of the surface energy was lower for the extracted TMW compared to the other sample groups, indicating an almost complete removal of the extractives. The FTIR spectra of the extracts showed the presence of phenolic compounds but also resin acids and aliphatic compounds.

  • 33.
    Larsson, P.T.
    et al.
    RISE, Innventia.
    Salmen, L.
    RISE, Innventia.
    Influence of cellulose supramolecular structure on strength properties of chemical pulp2014In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 68, no 8, p. 861-866Article in journal (Refereed)
  • 34.
    Lecourt, Micheal
    et al.
    FCBA, France.
    Pöhler, Tiina
    VTT, Finland.
    Hornatowska, Joanna
    RISE - Research Institutes of Sweden, Bioeconomy.
    Salmen, Lennart
    RISE - Research Institutes of Sweden, Bioeconomy, Biorefinery and Energy.
    Jetsu, Petri
    VTT, Finland.
    Density profiles of novel kraft pulp and TMP based foam formed thermal insulation materials observed by X-ray tomography and densitometry2018In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434XArticle in journal (Refereed)
    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.

  • 35. Li, D.
    et al.
    Iversen, Tommy
    RISE, Innventia.
    Ek, M.
    Hydrophobic materials based on cotton linter cellulose and an epoxy-activated polyester derived from a suberin monomer2015In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 69, no 6, p. 721-730Article in journal (Refereed)
    Abstract [en]

    Suberin is a natural hydrophobic material that could be used to improve the water repellency of cellulose surfaces. It is also abundant in the outer bark of birch (Betula verrucosa); birch bark is a side-stream product in Scandinavia from the forest industry, which is generally burned for energy production. A suberin monomer, cis-9,10-epoxy-18-hydroxyoctadecanoic acid, was isolated from birch outer bark and polymerized via lipase (immobilized Candida antarctica lipase B). The resulting epoxy-activated polyester was characterized by nuclear magnetic resonance (NMR) imaging, matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry, and size exclusion chromatography. Then the polyester was cured with tartaric or oxalic acid, and the crosslinked polyesters were characterized by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry. Hydrophobic materials were prepared by compression molding of polyester-impregnated cellulose sheets, and the final products were characterized by FTIR, cross-polarization magic angle spinning 13C NMR, and field-emission scanning electron microscopy. The water contact angle was significantly increased from 0° for the original cellulose sheets to over 100° for the produced hydrophobic materials.

  • 36.
    Lindfors, Eva-Lisa
    et al.
    RISE, STFI-Packforsk.
    Lindström, Mikael
    RISE, STFI-Packforsk.
    Iversen, Tommy
    RISE, STFI-Packforsk.
    Polysaccharide degradation in waterlogged oak wood from the ancient warship Vasa2008In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 62, no 1, p. 57-63Article in journal (Refereed)
    Abstract [en]

    A rather extensive degradation of cellulose and hemicelluloses was found in waterlogged oak wood samples from the ancient warship Vasa by size exclusion chromatography with the solvent system lithium chloride/N,N-dimethylacetamide (LiCl/DMAc). The degradation has mainly occurred after salvage of the wreck, probably as a consequence of keeping iron contaminated wood in contact with air. The most likely explanation is Fenton type of reactions degrading the wood polymers and oxidising reduced sulphur forms to sulphuric acid. An increased degradation rate of the Vasa wood can be anticipated in the future if the sulphuric acid cannot be neutralised and the oxidative reactions cannot be quenched.

  • 37.
    Malmquist, Lars
    Trätek..
    Sorption equilibrium in relation to the spatial distribution of molecules1995In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 49, p. 555-564Article in journal (Refereed)
  • 38. Malmquist, Lars
    et al.
    Söderström, Ove
    Trätek..
    Sorption equilibrium in relation to the spatial distribution of molecules. Application to desorption of water by wood1996In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 50, p. 437-448Article in journal (Refereed)
  • 39.
    Meyer, L
    et al.
    Faculty of Architecture and Landscape Sciences, Institute of Vocational Sciences in the Building Trade (IBW), Leibniz University Hannover.
    Brischke, C
    Faculty of Architecture and Landscape Sciences, Institute of Vocational Sciences in the Building Trade (IBW), Leibniz University Hannover.
    Treu, A
    Norwegian Forest and Landscape Institute.
    Larsson-Brelid, P
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Critical moisture conditions for fungal decay of modified wood by basidiomycetes as detected by pile tests2016In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 70, no 4, p. 331-339Article in journal (Refereed)
    Abstract [en]

    The aim of cell wall modification is to keep wood moisture content (MC) below favorable conditions for decay organisms. However, thermally modified, furfurylated, and acetylated woods partly show higher MCs than untreated wood in outdoor exposure. The open question is to which extent decay is influenced by the presence of liquid water in cell lumens. The present paper contributes to this topic and reports on physiological threshold values for wood decay fungi with respect to modified wood. In total, 4200 specimens made from acetylated, furfurylated, and thermally modified beech wood (Fagus sylvatica L.) and Scots pine sapwood (sW) (Pinus sylvestris L.) were exposed to Coniophora puteana and Trametes versicolor. Piles consisting of 50 small specimens were incubated above malt agar in Erlenmeyer flasks for 16 weeks. In general, pile upward mass loss (ML) and MC decreased. Threshold values for fungal growth and decay (ML≥2%) were determined. In summary, the minimum MC for fungal decay was slightly below fiber saturation point of the majority of the untreated and differently modified materials. Surprisingly, T. versicolor was able to degrade untreated beech wood at a minimum of 15% MC, and growth was possible at 13% MC. By contrast, untreated pine sW was not decayed by C. puteana at less than 29% MC. © 2016 by De Gruyter 2016.

  • 40.
    Moghaddam, Maziar S.
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Wålinder, M. E. P.
    Claesson, Per M.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik. KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Surface and Corrosion Science.
    Swerin, Agne
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Wettability and swelling of acetylated and furfurylated wood analyzed by multicycle Wilhelmy plate method2016In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 70, no 1, p. 69-77Article in journal (Refereed)
    Abstract [en]

    The wetting, dimensional stability and sorption properties of a range of modified wood samples obtained either by acetylation or furfurylation were compared with those of unmodified samples of the same wood species via a multicycle Wilhelmy plate method. Wettability measurements were performed with water and octane as the swelling and non-swelling liquids, respectively. It was found that acetylation reduces water uptake mainly by reducing the swelling. In comparison, furfurylation reduces both swelling and the void volume in the sample. To quantify the effect of the modification process of the wood properties, the parameters "liquid up-take reduction" and the "perimeter change reduction" were introduced, which were determined from multicycle Wilhelmy plate measurements. Compared with the acetylated wood, the furfurylated wood with a higher level of weight percent gain exhibited larger property changes on the surface and in terms of swelling and sorption properties.

  • 41.
    Moghaddam, Maziar Sedighi
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik. KTH Royal Institute of Technology, School of Architecture and the Built Environment, Department of Civil and Architectural Engineering, Building Materials.
    Heydari, G.
    Tuominen, Mikko
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Fielden, M.
    Haapanen, J.
    Mäkelä, J. M.
    Wålinder, M. E. P.
    Claesson, Per M.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik. Department of Chemistry Surface and Corrosion Science, KTH Royal Institute of Technology.
    Swerin, Agne
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Hydrophobisation of wood surfaces by combining liquid flame spray (LFS) and plasma treatment: Dynamic wetting properties2016In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 70, no 6, p. 527-537Article in journal (Refereed)
    Abstract [en]

    The hydrophilic nature of wood surfaces is a major cause for water uptake and subsequent biological degradation and dimensional changes. In the present paper, a thin transparent superhydrophobic layer on pine veneer surfaces has been created for controlling surface wettability and water repellency. This effect was achieved by means of the liquid flame spray (LFS) technique, in the course of which the nanoparticulate titanium dioxide (TiO2) was brought to the surface, followed by plasma polymerisation. Plasma polymerised perfluorohexane (PFH) or hexamethyldisiloxane (HMDSO) were then deposited onto the LFS-treated wood surfaces. The same treatment systems were applied to silicon wafers so as to have well-defined reference surfaces. The dynamic wettability was studied by the multicycle Wilhelmy plate (mWP) method, resulting in advancing and receding contact angles as well as sorption behavior of the samples during repeated wetting cycles in water. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were employed to characterise the topography and surface chemical compositions and to elucidate the question how the morphology of the nanoparticles and plasma affect the wetting behavior. A multi-scale roughness (micro-nano roughness) was found and this enhanced the forced wetting durability via a superhydrophobic effect on the surface, which was stable even after repeated wetting cycles. The hydrophobic effect of this approach was higher compared to that of plasma modified surfaces with their micro-scale modification.

  • 42.
    Moghaddam, Maziar Sedighi
    et al.
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials. KTH Royal Institute of Technology, Sweden.
    Van den Bulcke, Jan
    Ghent University, Belgium.
    Wålinder, Magnus E. P.
    KTH Royal Instituteof Technology, Sweden.
    Claesson, Per M.
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials. KTH Royal Institute of Technology, Sweden.
    Van Acker, Joris
    Ghent University, Sweden.
    Swerin, Agne
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials. KTH Royal Institute of Technology, Sweden.
    Microstructure of chemically modified wood using X-ray computed tomography in relation to wetting properties2017In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 71, no 2, p. 119-128Article in journal (Refereed)
    Abstract [en]

    X-ray computed tomography (XCT) was utilized to visualize and quantify the 2D and 3D microstructure of acetylated southern yellow pine (pine) and maple, as well as furfurylated pine samples. The total porosity and the porosity of different cell types, as well as cell wall thickness and maximum opening of tracheid lumens were evaluated. The wetting properties (swelling and capillary uptake) were related to these microstructural characteristics. The data show significant changes in the wood structure for furfurylated pine sapwood samples, including a change in tracheid shape and filling of tracheids by furan polymer. In contrast, no such changes were noted for the acetylated pine samples at the high resolution of 0.8

  • 43.
    Nordstierna, Lars
    et al.
    SP- Sveriges Tekniska Forskningsinstitut, Trätek.
    Westin, Mats
    SP- Sveriges Tekniska Forskningsinstitut, Trätek.
    Lande, Stig
    Karlsson, Olav
    Furó, István
    Avd för kemi.
    Towards novel wood-based materials: Chemical bonds between lignin-like model molecules and poly(furfuryl alcohol) studied by NMR2008In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 62, no 6, p. 709-713Article in journal (Refereed)
    Abstract [en]

    Wood modification with furfuryl alcohol is a non-toxic alternative to conventional preservation treatments. A process in which furfuryl alcohol polymerises in situ was previously proposed for chemical modification of wood. In the present work, liquid model systems were investigated using compounds that resemble repeating units of lignin to verify whether chemical bonds form between the furfuryl alcohol polymer and wood. Using different NMR spectroscopic techniques we confirmed that these model compounds do form covalent bonds with the polymerising polymer. The results indicate that the furan polymer grafts to lignin, supporting observations in similar studies performed with genuine wood materials.

  • 44.
    Nowak, Andrzej P.
    et al.
    KTH Royal Institute of Technology, Sweden ; Gdansk university of technology, Poland.
    Hagberg, Johan
    KTH Royal Institute of Technology, Sweden.
    Leijonmarck, Simon
    RISE - Research Institutes of Sweden, Swerea, Swerea KIMAB. KTH Royal Institute of Technology, Sweden.
    Schweinebarth, Hannah
    RISE - Research Institutes of Sweden, Bioeconomy, Biorefinery and Energy.
    Baker, Darren A
    RISE - Research Institutes of Sweden, Bioeconomy, Biorefinery and Energy.
    Uhlin, Anders
    RISE - Research Institutes of Sweden, Bioeconomy, Biorefinery and Energy.
    Tomani, Per
    RISE - Research Institutes of Sweden, Bioeconomy, Biorefinery and Energy.
    Lindbergh, Göran
    KTH Royal Institute of Technology, Sweden.
    Lignin-based carbon fibers for renewable and multifunctional lithium-ion battery electrodes2018In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, no 2, p. 81-90Article in journal (Refereed)
    Abstract [en]

    Lignin-based carbon fibers (LCFs) from the renewable resource softwood kraft lignin were synthesized via oxidative thermostabilization of pure melt-spun lignin and carbonization at different temperatures from 1000°C to 1700°C. The resulting LCFs were characterized by tensile testing, scanning electron microscopy (SEM), X-ray diffraction (XRD) and confocal Raman spectroscopy. The microstructure is mainly amorphous carbon with some nanocrystalline domains. The strength and stiffness are inversely proportional to the carbonization temperature, while the LCFs carbonized at 1000°C exhibit a strength of 628 MPa and a stiffness of 37 GPa. Furthermore, the application potential of LCFs was evaluated as negative electrodes in a lithium-ion battery (LIB) by electrochemical cycling at different current rates in a half-cell setup. The capacity drops with the carbonization temperature and the LCFs carbonized at 1000°C have a capacity of 335 mAh g-1. All LCFs showed good cycling stability. Because of the mechanical integrity and conductivity of the LCFs, there is no need to apply current collectors, conductive additives or binders. The advantage is an increased gravimetric energy density compared to graphite, which is the most common negative electrode material. LCFs show a promising multifunctional behavior, including good mechanical integrity, conductivity and an ability to intercalate lithium for LIBs.

  • 45.
    Oksman, Kristiina
    et al.
    RISE, Swerea, Swerea SICOMP.
    Lindberg, H.
    Luleå University of Technology.
    The Influence of a SBS Compatibilizer in Polyethylene-Wood Flour Composites1998In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 52, no 6, p. 661-666Article in journal (Refereed)
    Abstract [en]

    A styrene-butadiene-styrene (SBS) block copolymer has been used as a compatibilizer in a low density polyethylene/wood flour (LDPE/WF) composite system. Dynamic mechanical thermal analysis (DMTA) and a transmission electron microscopy (TEM) were used to investigate the interfacial properties in the composites. A high resolution study of the composite microstructure, and especially of the interfaces between the wood particles and LDPE matrix, indicated that the SBS compatibilizer was located at the interface region between the wood particles and LDPE matrix and partially covered the wood particle surfaces. The SBS was also found in the LDPE matrix. The unsaturated part of the copolymer was stained with osmium(VIII)tetraoxide (OsO4) to enhance contrast and to allow it to be detectable in TEM. Dynamic mechanical measurements confirmed interaction between polystyrene (PS) and wood in the PE/PS/WF system. The tan d peak of PS was shifted about 10°C to a higher temperature and also broadened when wood flour was added in the LDPE/PS blend.

  • 46.
    Olsson, Carina
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Sjöholm, Elisabeth
    RISE - Research Institutes of Sweden, Bioeconomy. RISE, Innventia.
    Reimann, Anders
    RISE - Research Institutes of Sweden, Bioeconomy. RISE, Innventia.
    Carbon fibres from precursors produced by dry-jet wet-spinning of kraft lignin blended with kraft pulps2017In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 71, no 4, p. 275-283Article in journal (Refereed)
    Abstract [en]

    A part of kraft lignin (KL) can be used as a value-added product without detracting the chemical recovery and the energy balance of the kraft mill. The focus of this study is the production of light-weight carbon fibres (CFS) from KL obtained by the LignoBoost process. For this purpose, crude KL and various cellulose products from kraft pulping of hardwood (HW) and softwood (SW) were dissolved in 1-ethyl-3-methylimidazolium acetate ([EMIm][OAc]) and submitted to dry-jet wet-spun to obtain precursor fibres containing 70% KL and 30% cellulose, which were thermally stabilised and further converted by thermal treatments into CF. The initial and final products were characterised with respect to, e.g. mole mass distribution, thermal properties, tensile strength and tensile modulus determination. The optimised precursor fibres are smooth and flexible with similar mechanical properties as commercial textile fibres. The best CFS made had a tensile strength of 780 MPa and a tensile modulus of 68 GPa and are thus stronger and stiffer than those produced by melt-spinning of SW-based lignins alone. The new CFS based on dry-jet wet-spun precursors still have a high potential for further improvements.

  • 47.
    Pilgård, Annica
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, Trätek.
    Alfredsen, Gry
    Gjelstrup Björdal, Charlotte
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, Trätek.
    Fossdal, Carl Gunnar
    Børja, Isabella
    qPCR as a tool to study basidiomycete colonization in wooden field stakes2011In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 65, no 6, p. 889-895Article in journal (Refereed)
  • 48.
    Pilgård, Annica
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, Trätek.
    Alfredsen, Gry
    Hietala, Ari
    Quantification of fungal colonization in modified wood: Quantitative real-time PCR as a tool for studies on Trametes versicolor2010In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 64, no 5, p. 645–651-Article in journal (Refereed)
    Abstract [en]

    Traditional wood preservatives based on biocides are effective against wood-deteriorating organisms because of their toxicity. By contrast, modified woods are non-toxic by definition. To investigate the efficiency of various wood modifications, quantitative real-time polymerase chain reaction (qPCR) was used to profile the DNA amounts of the white-rot fungus Trametes versicolor (L.) [Lloyd strain CTB 863 A] during an 8-week-long growth period in treated Pinus sylvestris (L.) sapwood. The studied wood was modified by acetylation, furfurylation, and thermal treatment. The traditional wood preservatives bis-(N-cyclohexyldiazeniumdioxy)-copper (Cu-HDO) and chromated copper arsenate (CCA) were used as references, whereas untreated P. sylvestris (L.) sapwood served as a control. The maximum levels of fungal DNA in native wood occurred at the end of the experiment. For all wood treatments, the maximum fungal DNA level was recorded after an incubation period of 2 weeks, followed by a decline until the end of the trial. For the preservative-treated woods, Cu-HDO showed the lowest level of fungal DNA throughout the experiment, indicating that exploratory hyphal growth is limited owing to the phytotoxicity of the treatment. The other treatments did not inhibit the exploratory hyphal growth phase. We conclude that qPCR studies of hyphal growth patterns within wood should provide a powerful tool for evaluating and further optimizing new wood protection systems.

  • 49.
    Ringman, Rebecka
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Material och produkter (TRm).
    Pilgård, Annica
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Hållbar Samhällsbyggnad.
    Brischke, Christian
    Richter, Klaus
    Mode of action of brown rot decay resistance in modified wood: a review2014In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 68, no 2, p. 239–246-Article in journal (Refereed)
  • 50.
    Rosenkilde, Anders
    AB Trätek.
    Measurement of moisture content profiles during drying of Scots pine using magnetic resonance imaging2004In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 58, no 2, p. 138-142Article in journal (Refereed)
    Abstract [en]

    Moisture content profiles with high spatial pixel resolution, 21 µm, were measured in Scots pine heartwood while drying from wet conditions to near equilibrium in the surface layer, (0–300 µm). The measuring technique used was Magnetic Resonance Imaging. In order to obtain magnetic resonance profiles with a high pixel resolution at both high and low moisture contents, a highg-radient permanent magnet was used. The results presented show one-dimensional moisture content profiles and mean moisture content development in the surface layer. In Scots pine heartwood, almost flat moisture content profiles were observed when the moisture content was above the fibre saturation level. When the mean moisture content in the surface layer decreases to the fibre saturation level, gradients start to build up from the surface towards the bulk of the sample although the bulk moisture content is far above the fibre saturation. Furthermore, the results presented in this study imply that a dry shell forms in the surface layer shortly after drying has begun. This dry shell controls the drying rate until the mean moisture content in the bulk decreases to the fibre saturation level.

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