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  • 1.
    Sekan, Alona S.
    et al.
    Institute of Food Biotechnology and Genomics, National Academy of Science of Ukraine, Kyiv, Ukraine.
    Myronycheva, Olena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Gryganskyi, Andrii P.
    LF Lambert Spawn Co., Coatesville, PA, USA.
    Blume, Yaroslav
    Institute of Food Biotechnology and Genomics, National Academy of Science of Ukraine, Kyiv, Ukraine.
    Green potential of Pleurotus spp. in biotechnology2019In: PeerJ, ISSN 2167-8359, E-ISSN 2167-8359, Vol. 7, article id e6664Article in journal (Refereed)
    Abstract [en]

    Background

    The genus Pleurotus is most exploitable xylotrophic fungi, with valuable biotechnological, medical, and nutritional properties. The relevant features of the representatives of this genus to provide attractive low-cost industrial tools have been reported in numerous studies to resolve the pressure of ecological issues. Additionally, a number of Pleurotus species are highly adaptive, do not require any special conditions for growth, and possess specific resistance to contaminating diseases and pests. The unique properties of Pleurotus species widely used in many environmental technologies, such as organic solid waste recycling, chemical pollutant degradation, and bioethanol production.

    Methodology

    The literature study encompasses peer-reviewed journals identified by systematic searches of electronic databases such as Google Scholar, NCBI, Springer, ResearchGate, ScienceDirect, and ISI Web of Knowledge. The search scheme was divided into several steps, as described below.

    Results

    In this review, we describe studies examining the biotechnological feasibility of Pleurotus spp. to elucidate the importance of this genus for use in green technology. Here, we review areas of application of the genus Pleurotus as a prospective biotechnological tool.

    Conclusion

    The incomplete description of some fungal biochemical pathways emphasises the future research goals for this fungal culture.

  • 2.
    Raudoniene, Jolanta
    et al.
    Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Vilnius, Lithuania.
    Skaudzius, Ramunas
    Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Vilnius, Lithuania.
    Zarkov, Aleksej
    Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Vilnius, Lithuania.
    Selskis, Algirdas
    Center for Physical Sciences and Technology, Vilnius, Lithuania.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Kareiva, Aivaras
    Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Vilnius, Lithuania.
    Garskaite, Edita
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Wet-chemistry synthesis of shape-controlled Ag3PO4 crystals and their 3D surface reconstruction from SEM imagery2019In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 345, p. 26-34Article in journal (Refereed)
    Abstract [en]

    A simple chemical solution-based synthesis route has been developed to prepare uniform and shape-controllable Ag3PO4 crystals. Tetrapod- and cube-shaped crystals having a size of about 9–10 μm were prepared from AgNO3 and NH4H2PO4 precursors, and pseudo-octahedral (equiaxial) crystals were prepared from AgNO3 and (NH4)2HPO4. TEM analysis revealed Ag3PO4 crystals to be electron beam sensitive materials, which under a voltage of 200 kV decompose to the metallic Ag, thereby demonstrating the difficulty in determining crystal facets and structural defects using conventional electron diffraction studies. UV–Vis diffuse reflectance spectroscopy was used to study the correlation between structural and optical properties of surfaces of Ag3PO4 crystals. Furthermore, a spatial 3-dimentional (3D) reconstruction of Ag3PO4 surface structures was performed from SEM images. The reconstruction produced realistic 3D mesh models, insomuch that the 3D reconstructed structures provided extra information about the examined crystals. Results suggested that the proposed synthesis route and performed spatial reconstruction of Ag3PO4 had the potential for simulating processing conditions to produce various microcrystals and explore material surface structures and reconstruction of microstructures.

  • 3.
    Myronycheva, Olena
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Öhman, Micael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Distribution of low-molecular lipophilic extractives beneath the surface of air- and kiln-dried Scots pine sapwood boards2018In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, no 10, article id e0204212Article in journal (Refereed)
    Abstract [en]

    During industrial wood drying, extractives migrate towards the wood surfaces and make the material more susceptible to photo/biodegradation. The present work provides information about the distribution, quantity and nature of lipophilic substances beneath the surface in air- and kiln-dried Scots pine (Pinus sylvestris L.) sapwood boards. Samples were taken from knot-free sapwood surfaces and the composition of lipophilic extractives, phenols and low-molecular fatty/resin acids layers at different nominal depths below the surface was studied gravimetrically, by UV-spectrometry and by gas chromatography-mass spectrometry (GC-MS). The concentration of total extractives was significantly higher in kiln-dried than in air-dried samples and was higher close to the surface than in the layers beneath. The scatter in the values for the lipophilic extractives was high in both drying types, being highest for linoleic acid and slightly lower for palmitic, oleic and stearic acids. The amount of fatty acids was low in kiln-dried boards, probably due to a stronger degradation due to the high temperature employed. The most abundant resin acid was dehydroabietic acid followed by pimaric, isopimaric, and abietic acids in both drying types. It is concluded that during kiln-drying a migration front is created at a depth of 0.25 mm with a thickness of about 0.5 mm.

  • 4.
    Myronycheva, Olena
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Growth of mold and rot fungi on copper-impregnated Scots pine sapwood: Influence of planing depth and inoculation pattern.2018In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 13, no 4, p. 8787-8801Article in journal (Refereed)
    Abstract [en]

    The biocidal properties of an industrially used copper-based preservative were evaluated at different planing depths on exposure of pine wood to mold fungi in direct and indirect contamination methods, with simultaneous verification of white rot fungi virulence on wood. The preservative was an aqueous solution of copper carbonate, 2-aminoethanol, and quaternary ammonium compounds. Full cell preservative impregnation efficiency against visual mold fungi growth was tested on sapwood surfaces planed to different depths before impregnation. The virulence of two white rot fungal strains of Trametes versicolor (441 and JPEI) against the dried non-impregnated and impregnated wood samples was also tested. The unplaned surface of impregnated timber was occupied by air-borne contaminants, such as Paecilomyces variottiand Aspergillus niger up to 30%, and, even after impregnation it was necessary to process the surface to avoid micro-fungi settlement. The virulence of the tested rot fungi strains was confirmed by the aggressive degradation of non-impregnated wood with a mass loss of over 40%. Both Trametes sp. strains degraded the preservative-impregnated wood with a mass loss of 3.1% to 4.8%, but degradation by the JPEI strain was more intensive and more dependent on planing depth than the other strain (441).

  • 5.
    Myronycheva, Olena
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sidorova, Ekaterina
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hyperspectral Imaging Surface Analysis for Dried and Thermally Modified Wood: An Exploratory Study2018In: Journal of Spectroscopy, ISSN 2314-4920, E-ISSN 2314-4939, article id 7423501Article in journal (Refereed)
    Abstract [en]

    Naturally seasoned, kiln-dried, and thermally modified wood has been studied by hyperspectral near-infrared imaging between 980 and 2500 nm in order to obtain spatial chemical information. Evince software was used to explore, preprocess, and analyse spectral data from image pixels and link these data to chemical information via spectral wavelength assignment. A PCA model showed that regions with high absorbance were related to extractives with phenolic groups and aliphatic hydrocarbons. The sharp wavelength band at 2135 nm was found by multivariate analysis to be useful for multivariate calibration. This peak represents the largest variation that characterizes the knot area and can be related to areas in wood rich in hydrocarbons and phenol, and it can perhaps be used for future calibration of other wood surfaces. The discriminant analysis of thermally treated wood showed the strongest differentiation between the planed and rip-cut wood surfaces and a fairly clear discrimination between the two thermal processes. The wavelength band at 2100 nm showed the greatest difference and may correspond to stretching of C=O-O of polymeric acetyl groups, but this requires confirmation by chemical analysis.

  • 6.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Myronycheva, Olena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Jones, Dennis
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Elustondo, Diego
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Thermally modified wood treated with methacrylate2018In: Proceedings IRG Annual Meeting IRG49 Scientific Conference on Wood Protection Sandton, Johannesburg, South Africa 29 April-3 May, 2018Conference paper (Refereed)
    Abstract [en]

    Thermally modified timber (TMT)from Scots pine sapwood similar to Thermo-D quality was impregnated with methacrylate resin by the hot-and-cold method and subsequently cured at elevated temperatures. The results showedthat methacrylate resin could be used to reduce colouring of painted TMT wood during accelerated weathering probably by hindering the migration of extractives. The resin itself did not reduce greying of the unpainted wood. Hardness was only slightly improved by treatment with the resin probably due to a higher density of the material. Formation of blisters occurred but wasreduced by treatment with the resin. Resistance to mould growth by a mixture of Aureobasidium pullulans, Cladosporium cladosporioides, Aspergillus versicolor, Penicillium purpurogenumwas performed by applying EN-15457:2014. Treatment with methacrylic resin hindered the colonisation of the three last mouldfungi.

  • 7.
    Myronycheva, Olena
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Bandura, Iryna
    Department of Technology Processing and Storag e of Agricultural Products, Tavria State Agrotecnological University.
    Bisko, Nina
    Department of Mycology, Institute of Botany, National Academy of Sciences of Ukraine.
    Grygansky, Andrii P.
    LF Lambert Spawn Co..
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Assessment of the Growth and Fruiting of 19 Oyster Mushroom Strains for Indoor Cultivation on Lignocellulosic Wastes2017In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, no 3, p. 4606-4626Article in journal (Refereed)
    Abstract [en]

    AbstractTwelve Pleurotus ostreatus (Jacq. ex Fr.) P. Kumm and six Pleurotus pulmonarius (Fr.) Quél. strains were characterized from the National Culture Collection of Mushrooms, Institute of Botany Kholodny, National Academy of Science, Kyiv, Ukraine (IBK). The strains were grown under commercial conditions on a mixture of wheat straw and sunflower shells under both winter and summer temperatures typical for those climatic conditions. The strains were divided into three groups according to their growing patterns. Important characteristics were compared with a commercial analogue, HK-35, such as vegetative growth, generative growth, and biological efficiency (1.9- to 3.1-fold), and were recorded for strains 2251, 2292, 2316, 2319, and 2320 of P. ostreatus and 2314 of P. pulmonarius. Strains 2251, 2292, 2301, 2321 and 2323 were the most suitable for commercial production, while strains 2319 and 2320 could satisfy processing industry requirements with their high biological efficiency. Strains 2287 and 2317 produced high-quality fruit bodies but probably required a higher temperature for cultivation. Strain 2318 might be attractive for some consumers due to its unique and unusual fruit body shape. Strain 2314 was the most promising for summer cultivation, while strain 537 produced the highest quality fruit bodies.KeywordsOyster mushroom; Strain; Vegetative growth; Fruit body; Biological efficiency; Conversion Factor (CF); Asymmetry of the Fruit Body Cap (Cas)

  • 8.
    Hemmilä, Venla
    et al.
    Department of Forestry and Wood Technology, Linnaeus University.
    Adamopoulos, Stergios
    Department of Forestry and Wood Technology, Linnaeus University.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Kumar, Anuj
    Department of Forestry and Wood Technology, Linnaeus University.
    Development of sustainable bio-adhesives for engineered wood panels: A Review2017In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 61, p. 38604-38630Article in journal (Refereed)
    Abstract [en]

    Changes in both formaldehyde legislations and voluntary requirements (e.g. Germany RAL) are currently the driving factors behind research on alternatives to amino-based adhesives; moreover, consumer interest in healthy and sustainable products is increasing in bio-based adhesives. Sources of formaldehyde emissions in wood-based panels as well as different emission test methods have been discussed, and the main focus of this review is on the research conducted on sustainable bio-based adhesive systems for wood panels. Lignin, tannin, protein, and starch have been evaluated as both raw materials and adhesive alternatives to existing amino-based thermosetting adhesives. Adhesion improving modifications of these bio-based raw materials as well as the available and experimental crosslinkers have also been taken into account.

  • 9.
    Cristescu, Carmen
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Markers of quality in self-bonded beech boards2017Conference paper (Refereed)
    Abstract [en]

    A self-bonding phenomenon takes place when five layers of beech (Fagus SylvaticaL.) veneers are pressed at temperatures higher than 200ºC. If the pressing temperature between veneer surfaces reaches at least 225ºC during pressing and if the pressure applied is optimal, water-resistant bonds are formed between veneers. This study investigates the relation of thickness reduction (marker of compression) and mass loss (marker of heat treatment intensity) to boards quality. The effect of water and water vapour on the bondings between veneer in boards pressed at 200, 225 and 250ºC is studied. The conclusion is that pressing 5 layers of 2 mm rotary-cut beech veneer parallel-fibered at 225ºC, 5 MPa and 300 s leads to a thickness reduction of 33.4 % and mass loss of 1.23 %; in such boards bondings are not resistant to liquid water but are resistant to vapour after one adsorption-desorption cycle. When pressing at 250ºC, 5 MPa and 300 seconds, the thickness reduction is 50% and the mass loss 4%; in such boards no delamination was observed when soaked in water. Boards pressed athigher temperature show lower hygroscopicity. Their equilibrium moisture content (EMC) rangedbetween 3.6 and 7%. Based on the results of this study it ishypothesised that the decay resistance of self-bonded boards will increase when increasing the severity of the hot-pressing.

  • 10.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Myronycheva, Olena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Öhman, Micael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Multivariate modeling of mould growth in relation to extractives in dried Scots pine sapwood2017In: Proceedings IRG Annual Meetin, 2017, article id 17-20629Conference paper (Refereed)
    Abstract [en]

    Influence of extractives on mould growth on Scots pine sapwood dried in air or in kiln was studied. Boards were sprayed with water mixtures of spores of the fungal species Penicillium sp., Aspergillus sp., Mucor sp., Paecilomyces sp., Trichoderma sp., treated at a temperature of 22ºC at 90% RH, classified into a percentage of covered area. Acetone and water extracts were isolated and analyzed for sugars, nitrogen, ash, resin/fatty acids, glycerol, and phenols. A multivariate Orthogonal Partial Least Squares (OPLS) regression model was developed to study relations between the extent of mould coverage of boards and chemical content. The model describes 51% variability in X and 69% in Y with prediction power of 55%. The results indicated that total acetone soluble extractives and sugars like glucose contributed to increased mould growth whereas fatty acids prevent mould growth.

  • 11.
    Chen, Tingjie
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Wu, Zhenzeng
    College of Material Engineering, Fujian Agricultural and Forestry University.
    Wei, Wei
    College of Material Engineering, Fujian Agricultural and Forestry Universit.
    Xie, Yongqun
    College of Material Engineering, Fujian Agricultural and Forestry Universit.
    Wei, Qihua
    College of Material Engineering, Fujian Agricultural and Forestry Universit.
    Wang, Alice
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Optimizing Refining Conditions of Pinus massoniana Cellulose Fibers for Improving the Mechanical Properties of Ultra-Low Density Plant Fiber  Composite (ULD_UFC)2017In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, no 1, p. 8-18Article in journal (Refereed)
    Abstract [en]

    Response surface methodology was used to optimize the refining conditions of Pinus massoniana cellulose fiber and to improve the mechanical properties of ultra-low density plant fiber composite (ULD_PFC). The effects and interactions of the pulp consistency (X1), the number of passes (X2), and the beating gap (X3) on the internal bond strength of ULD_PFC were investigated. The results showed that the optimum internal bond strength (91.72 ± 2.28 kPa) was obtained under the conditions of 8.0% pulp consistency, two passes through the refiner, and a 30.0 μm beating gap. Analysis of the physical properties of the fibers and handsheets showed that the fibrillation of fibers with optimum refining conditions was improved. Also, the tear index of the optimal specimen was 13.9% and 24.5% higher than specimen-1 with a lowest beating degree of 24 oSR and specimen-6 with a highest beating degree of 73 oSR, respectively. Consequently, the optimal refining conditions of the fibers are valid for preparing ULD_PFCs.

  • 12.
    Bandura, Iryna
    et al.
    Tavria State Agrotechnological University .
    Myronycheva, Olena
    Tavria State Agrotechnological University .
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Anike, F.N.
    North Carolina A&T State University, Greensboro.
    Isikhuemhen, O.S.
    North Carolina A&T State University, Greensboro.
    Pretreatment of wheat straw and solid state fermentation improves yield and biological efficiency in Pleurotus ostreatus Jacq) P. Kumm. mushroom production2017In: Advances in medicinal mushroom science: Building bridges between Western and Eastern medicine : th International medicinal mushrooms conference : book of abstracts / [ed] Maria Letizia Gardano, Giuseppe Venturella, Palermo, Italy: University of Palermo , 2017, p. 41-43Conference paper (Refereed)
    Abstract [en]

    The pretreatment method for generating substrate for large scale production of oyster mushroom is critical for determining high yield and biological efficiency (BE). The aim of this study was to develop an optimal storage and pretreatment procedure for substrate used in oyster mushroom production. The effect of wheat straw substrate storage (outdoor- open air versus indoor- closed barn) and pretreatment (steam (SP) and hot water (HWP) pasteurization and solid state fermentation (SSF)) on substrate microbiological quality, mushroom yield/BE were investigated during the cultivation of Pleurotus ostreatus strain HK-35. The influence of temperatures used during solid state fermentation on BE was also investigated. There were significant changes among the parameters measured (moisture, total nitrogen, ash content, C/N ratio and total microbial count (CFU) between indoor and outdoor storage. The indoor storage gave higher values. With outdoor storage, CFU showed about 800 times increase. Among the substrate treatment methodstested (SP-control, HWP and SSF), SSF gave consistently higher fruit body yield and BE which ranged from 77-86% compared to the control which ranged from 40-53%. Also SSF conducted at higher temperature (74°C) gave higher BE of 81.2% compared to one conducted at lower temperature (63°C), which gave BE of 69.4%. We consider these findings to be useful in further studies on the redesign oF industrial production systems, which can make oyster mushroom production more profitable in Ukraine and beyond.

  • 13.
    Bandura, Iryna
    et al.
    Tavria State Agrotechnological University, Department of technology of processi ng and storage of agricultural products.
    Myronycheva, Olena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Assessment of Raw Plant material and Substrate for Efficient production of Oyster Mushrooms (Pleurotusostreatus (Jacq.) P. Kumm.)2016In: Ochrana drevín a dreva 2016: zborník recenzovaných vedeckých prác a abstraktov / [ed] Pavol Hlaváč , Zuzana Vidholdová, Zvolen: Technická univerzita vo Zvolene , 2016, p. 27-33Conference paper (Refereed)
    Abstract [en]

    Microbial analysis of raw materials and substrate during all phases of thermal processing revealed the most efficient methods for industrial mushroom cultivation. The aerobic fermentation in the upper layer is preferable if using long term stored material. The oyster mushroom strain HK-35 was used for testing. An increase in biological efficiency with 37% was found for aerobic fermentation in comparison with stream processing. From evaluation of temperature influence during pasteurization phase, the biological efficiency increased with 11% for tested temperature treatment at 74±3°С in comparison to the standard at 63±3°С.

  • 14.
    Chen, Tingjie
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. tingjie.chen@ltu.se .
    Xie, Yongqun
    Department of Material Science and Engineering, Fujian Agriculture and Forestry University, Fuzhou.
    Wei, Qihua
    Department of Material Science and Engineering, Fujian Agriculture and Forestry University, Fuzhou.
    Wang, Alice
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Liu, Jinghong
    Department of Material Science and Engineering, Fujian Agriculture and Forestry University, Fuzhou.
    Effect of Refining on Physical Properties and Paper Strength of Pinus massoniana and China Fir Cellulose Fibers2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, no 3, p. 7839-7848Article in journal (Refereed)
    Abstract [en]

    To obtain a suitable refining process for Pinus massoniana cellulose fibers (PMCF) and China fir cellulose fibers (CFCF), the effects of the beating gap and the pulp consistency on the physical properties and the morphology of the two cellulose fibers were investigated. The results showed that the physical properties of the PMCF and the CFCF were well affected by the beating gap and the pulp consistency. The CFCF showed a smaller weight-average length and width than that of the PMCF. The CFCF exhibited smaller weight-average length, width, and kink index than the PMCF. It is easy to get the high beating degree, indicating it is more easily to be refined. Additionally, the tensile index and burst index of PMCFP and CFCFP increased with increasing beating degree, while the tear index decreased. Compared to the CFCF, the paper made from PMCF had superior strength properties. Consequently, the PMCF was suitable for refining with a high pulp consistency and a medium beating gap, whereas the CFCF had a medium pulp consistency and a big beating gap.

  • 15.
    Chen, Tingjie
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Xie, Yongqun
    College of Material Engineering, Fujian Agriculture and Forestry University.
    Wei, Qihua
    College of Material Engineering, Fujian Agriculture and Forestry University.
    Wang, Xiaodong (Alice)
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Liu, Jinghong
    College of Material Engineering, Fujian Agriculture and Forestry University.
    Lin, Ming
    College of Material Engineering, Fujian Agriculture and Forestry University.
    Improving the Mechanical Properties of Ultra-Low Density Plant Fiber Composite (ULD_PFC) by Refining Treatment2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, no 4, p. 8558-8569Article in journal (Refereed)
    Abstract [en]

    To improve the mechanical properties of ultra-low density plant fiber composite (ULD_PFC), a suitable beating process to improve the fibrillation of cellulose fibers and maintain their length was investigated. The physical properties of cellulose fibers and papers, surface chemical bonds, and internal bond strength (IB) of ULD_PFCs were analyzed. The results showed that the beating degrees, degree of fibrillation, and fiber fines increased with the decreasing of beating gap, except for the fiber weight-average length, width, kink index, and curl index. The tensile index and burst index of paper showed an increasing trend with an increase in beating degree, while the tear index showed a decreasing trend. FTIR results showed that intermolecular and intramolecular hydrogen bonds in ULDF were broken. A suitable beating gap of 30 μm with a beating degree of 35 °SR was obtained. The corresponding IB was 50.9 kPa, which represented an increase of 73.1% over fibers with a beating degree of 13 °SR.

  • 16.
    Elustondo, Diego
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Myronycheva, Olena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sundqvist, Bror
    SP Technical Research Institute of Sweden.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Localized Wood Surface Modification: Part I: Method Characterization2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, no 1, p. 283-295Article in journal (Refereed)
    Abstract [en]

    This study assesses the potential of an open process for treatment of European Scots pine (Pinus sylvestris) with chemicals that could potentially make the surfaces stronger, more dimensionally stable, or more durable, depending on the treatment solution. The method provides an intermediate solution between full volume impregnation by pressure treatment and superficial surface treatment by dipping. Figuratively speaking, the process creates the equivalent of a layer of coating applied below the wood surfaces rather than above. Two different techniques were compared, namely, heating-and-cooling (H&C) and compression-and-expansion (C&E). Taking into account that commercial suppliers recommend 0.15 to 0.25 L/m2 of coating in sawn wood and 0.1 to 0.15 L/m2 in planed wood surfaces, then this study demonstrates that the H&C method can impregnate an equivalent amount of solution under the surfaces in less than 15 min using treatment temperatures below 150 °C.

  • 17.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Cristescu, Carmen
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Autoadhesion of laminated boards from Scots pine veneers: effect of oxidative pretreatment2015In: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 11, no 4, p. 110-115Article in journal (Refereed)
    Abstract [en]

    This paper presents results from studies on the pre-treatment of veneers from Scots pineusing hydrogen peroxide and a ferrous catalyst followed by pressing at 220, 230, and 240°C. Thetreatment gave boards that did not delaminate when exposed to water followed by drying of roomtemperature, whereas boards without a pre-treatment delaminated. The press-plate temperature didnot influence the extent of delamination, but the thickness swelling was lower at higher presstemperature. Analysis of extracts from the oxidative pre-treated and hot-pressed surface materialusing UV-spectroscopy was compared with analysis of bondlines from water-stable laminated boardsfrom beech.

  • 18.
    Cristescu, Carmen
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Could colour predict hardness of hot-ptressed self-laminated beech boards2015In: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 11, no 4, p. 150-156Article in journal (Refereed)
    Abstract [en]

    Laminated self-bonded densified boards were obtained by pressing five veneers of beech(Fagus sylvatica L.) parallel-grain-oriented, without adhesive and without surface activation. Theboards were pressed according to an experimental design based on fifteen different combinations ofpressing parameters: temperature (200, 225, and 250°C), pressure (4, 5, and 6MPa), and time (240,300, and 360s). The image of the 40 board edges (radial sections) was analysed with ImageJ softwarein the red-green-blue (RGB) colour space. Brinell hardness tests were also performed. The resultsshow an almost linear relation between the brightness values (defined as the arithmetic mean of theRGB channels) and the Brinell hardness. It is suggested that brightness is a predictor of strength forself-bonded laminated boards.

  • 19.
    Elustondo, Diego
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sidorova, Ekaterina
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Development of method for surface modification of wood.2015In: Proceedings of the Eighth European Conference on Wood Modification: ECWM8 / [ed] Mark Huges; Lauri Rautkari; Tuuli Uimonen; Holger Militz; Brigitte Junge, Helsinki: Aalto University, School of Chemical Engineering , 2015, p. 137-140Conference paper (Refereed)
  • 20.
    Cristescu, Carmen
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Ekevad, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Influence of pressing parameters on mechanical and physical properties of self-bonded laminated beech boards2015In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 10, no 2, p. 205-214Article in journal (Refereed)
  • 21.
    Niu, Min
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Wang, Xiaodong (Alice)
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Xie, Yongqun
    Fujian Agriculture and Forestry University.
    Microstructure of Burned Ultra-Low-Density Fiberboards using Plant Fiber as the Matrix and Si-Al compounds as the Filler2015In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 10, no 2, p. 2903-2912Article in journal (Refereed)
    Abstract [en]

    Ultra-low-density fiberboards (ULDFs) were prepared by a liquid frothing technique using plant fibers as the matrix and Si-Al compounds as the filler to be used as a versatile bio-based composite. Si-Al compounds played an important role in the fire properties of ULDFs. Fire intensity and the amount of volatiles were significantly restrained because of the Si-Al compounds. To determine the combustion mechanism of ULDFs treated by Si-Al compounds, the microstructure of burned specimens was tested by chemical analysis, X-ray diffractometer (XRD), and infrared spectrometer (IR). According to the results from gas chromatography, glucose, xylose, and mannose disappeared in the bottom ashes. After combustion, the XRD profiles of the two ashes became weaker and broader; the sharpest peaks at 18.6o (2) that represented Si-Al compounds remained; the obvious peaks at 22o (2) from cellulose were gone. The results from IR suggested the characteristic functional groups OH, CH, and C=O from carbohydrate also disappeared, and absorbance at 1200 to 400 cm-1, which attributed to the vibration of Si-O, Al-O, and Si- O-Si bonds, increased. In conclusion, fibers are almost completely pyrolyzed at 780 °C. The crystalline structure of Si-Al compounds is rearranged and more amorphous silicon oxide and aluminum oxide are generated.

  • 22.
    Niu, Min
    et al.
    Fujian Agriculture and Forestry University, Fuzhou, China.
    Wang, Xiaodong (Alice)
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Xie, Yongqun
    Fujian Agriculture and Forestry University.
    Morphology of Burned Ultra-low Density Fiberboards2015In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 10, no 4, p. 7292-7301Article in journal (Refereed)
    Abstract [en]

    The synergistic effect of two fire retardants, a Si-Al compound and chlorinated paraffin, was tested on ultra-low density fiberboards (ULDFs). To further understand the mechanism of fire retardancy, morphologies of unburned and burned ULDFs were studied using a scanning electron microscope with energy dispersive spectroscopy. It was found that as the volume of the burned ULDFs shrank, some crevices appeared. In addition, less fly ash formed on the top of specimens, and more bottom ashes remained in the original framework, with a clear network of structure built by the fibers. Carbon was almost absent in the fly ash; however, the weight ratio of C in the bottom ashes reached the maximum (> 43%) of the composition. Oxygen, Al, and Si appeared to have varying weight ratios for different ashes. Oxygen content increased with increasing Si and Al contents. Furthermore, Cl sharply decreased to less than 1% after combustion. Therefore, upon combustion, it was found that almost all of the substances in ULDFs, except for the Si-Al compound, were pyrolyzed to volatile carbon oxides and Cl compounds, especially the fly ash and lightweight C compounds.

  • 23.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Cristescu, Carmen
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Neyses, Benedikt
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Pretreatment of veneers with hydrogen peroxide for self-bonded laminated boards.2015In: Proceedings of the Eighth European Conference on Wood Modification: ECWM8 / [ed] mark Huges; Lauri Rautkari; Tuuli Uimonen; Holger Militz; Brigitte Junge, Helsinki: Aalto University, School of Chemical Engineering , 2015, p. 305-310Conference paper (Refereed)
  • 24.
    Yoon, Kukjin
    et al.
    Graduate School of Life and Environmental Sciences, University of Tsukuba.
    Takahashi, Shiho
    Forestry and Forest Products Research Institute, Tsukuba, Ibaraki.
    Nge, Thi Thi
    Graduate School of Life and Environmental Sciences, University of Tsukuba.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. Forestry and Forest Products Laboratory, Tsukuba, Ibaraki.
    Nakagawa-izumi, Akiko
    Graduate School of Life and Environmental Sciences, University of Tsukuba.
    Ohi, Hiroshi
    Graduate School of Life and Environmental Sciences, University of Tsukuba.
    Uraki, Yasumitsu
    Faculty of Agriculture, Hokkaido University, Sapporo.
    Yamada, Tatsuhiko
    Graduate School of Life and Environmental Sciences, University of Tsukuba, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki.
    Thermal Melting of Lignin Derivates Prepared from Dried Black Liquor Powder of Softwood Soda-AQ Cooking and Polyehylene Glycol2015In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 10, no 1, p. 912-921Article in journal (Refereed)
  • 25.
    Niu, Min
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Wang, Alice
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Xie, Yongqun
    Fujian Agriculture and Forestry University, Department of Wood Science & Technology.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Cai, LiLi
    Fujian Agriculture and Forestry University, Department of Wood Science & Technology.
    Effect of Si-Al compounds on fire properties of ultra-low density fiberboard2014In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 9, no 2, p. 2415-2430Article in journal (Refereed)
    Abstract [en]

    An ultra-low density fiberboard was made of plant fiber using a liquid frothing approach. The inflammability of the plant fiber limited its application as a candidate for building insulation materials and packaging buffering materials. Si-Al compounds were introduced into the foaming system because of the high temperature resistance of Si and Al compounds. The results from energy-dispersive spectroscopy suggested that the Si and Al relatively evenly covered the surface of the fibers, and their weight ratios in the material increased as a function of the amount of Si-Al compounds. The increasing weight ratios of Si and Al affected the fire properties of the material, reducing the released amount of heat, smoke, and off-gases such as CO and CO2, as well as decreasing the mass loss percentage, shown through the use of a Cone Calorimeter. It follows that Si-Al compounds have an evident collaborative effect on the halogen fire retardant. The system can effectively restrain the fire hazard intensity and the yields of solid and gas volatiles.

  • 26.
    Hemmilä, Venla
    et al.
    Linnéuniversitetet.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Modified Wood-Protein Adhesive Bondline Strength Development during Curing2014In: The seventh European Conference on Wood Modification: Book of Abstracts / [ed] Lina Nunes; Dennis Jones; Callum Hill; Holger Militz, Lissabon, 2014, p. 134-137Conference paper (Refereed)
  • 27.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Dagbro, Ola
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Granlund, Kurt
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Soluble degradation products in thermally modified wood2014In: Final Cost Action FP0904 Conference: “Recent Advances in the Field of TH and THM Wood Treatment” : May 19-21, 2014, Skellefteå, Sweden : book of abstracts / [ed] Mojgan Vaziri; Dick Sandberg, Skellefteå: Luleå tekniska universitet, 2014, p. 16-17Conference paper (Refereed)
  • 28. Cristescu, Carmen
    et al.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Changes in content of furfurals and phenols in self-bonded laminated boards2013In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 8, no 3, p. 4056-4071Article in journal (Refereed)
    Abstract [en]

    Pressing beech veneers at high temperatures has been shown to be a reliable method for manufacturing laminated boards without adhesives. The reasons behind the self-bonding phenomenon as well as the causes of the waterproof character gained by the boards being pressed at 250 degrees C were investigated. Water leachates from the dried and the hot-pressed veneers were analysed by UV-spectroscopy, high-performance liquid chromatography (HPLC), and solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance (CP/MAS 13C NMR). Press-plate temperatures during hot pressing were 200, 225, and 250 degrees C. After pressing, an increased content of 5-(hydroxymethyl) furfural (not at 250 degrees C) and conjugated phenols was observed in the bonding lines (interfaces) compared to the inner part of veneers of the self-bonded boards. Furfural contents were low and relatively similar, but 5-(hydroxymethyl) furfural (HMF) showed an abrupt decrease in the bonding line when the temperature increased from 200 degrees C to 225 degrees C and especially to 250 degrees C. The contribution of caramelization to browning and bonding is suggested. In studies with CP/MAS 13C NMR, a higher content of phenolic units in beech lignin was observed during hot pressing at 225 degrees C. Homolytical cleavage of beta-O-4 structures in lignin as well as the condensation reactions involved are discussed

  • 29. Yang, Qian
    et al.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Ahmed, Sheikh Ali
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Dimensional stability and water repellency of european aspen improved by oxidized carbohydrates2013In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 8, no 1, p. 487-498Article in journal (Refereed)
    Abstract [en]

    Small samples from European aspen (Populus tremula L.) were impregnated with carbohydrates oxidized by Fenton’s reagent using water in a vacuum, followed by heating in an oven at 103°C. An antiswelling efficiency (ASE) of around 45% for wood treated with oxidized glucose and 35% for wood treated with oxidized sucrose was obtained. Samples treated with oxidized carbohydrates gave water repellent effectiveness (WRE) values over 35%. The decrease in cell wall thickness during impregnation was about 18% less in the presence of oxidized glucose than samples only treated with Fenton’s reagent. An ASE of 20% for the wood samples that had been treated with oxidized glucose was obtained after 7 days of soaking in water. The reasons for the improvement in dimensional stability are discussed in this work.

  • 30.
    Sehlstedt-Persson, Margot
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Persson, Fredrik
    SP Trätek.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Ahmed, Sheikh Ali
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Virkestorkningens inverkan på impregnerbarhet i furusplint – Del II: TCN Delrapport 12013Report (Other academic)
    Abstract [sv]

    Projektets målsättning är att undersöka om och hur virkestorkning påverkar impregnerbarhet i furusplint med vattenbaserat kopparmedel, samt att ge rekommendationer om hur torkningsbetingelserna kan göras så gynnsamma som möjligt för ett bra impregneringsresultat. Det bör tydliggöras att det virke som impregnerats i denna studie inte kommer att säljas inom detaljhandeln. Virket anses inte heller vara representativt för impregnerat virke då det har impregnerats vid fuktkvoter som avsiktligt avviker från normala förhållanden och som kan antas vara ogynnsamma för inträngningen. Virket impregnerades enligt Nordiska Träskyddsföreningen (NTR) klass AB.I delsteg 1 som avrapporteras i denna rapport, har huvudfrågan varit att undersöka inverkan av fuktkvotsnivå och maxtemperatur under torkningen på impregneringsresultatet. Försöksmaterialet har bestått av totalt 553 hyvlade bräder och plank (28 resp. 48 mm). Både planken och bräderna sågades fram ur centrumutbyte och innehöll därför kärnved. Virket torkades industriellt vid 60°C och 80°C maxtemperatur till tre målfuktkvoter: 24 %, 18 % och 10 %. Efter impregnering har samtliga virkesstycken kapats upp var 50:e cm och impregneringsresultat har analyserats visuellt enligt NTR:s bedömningsgrunder. Vissa kemiska analyser har även utförts för att undersöka om och hur extraktiver och fetter kan förklara impregneringsmissarna i bräderna. Undersökningen visar att virkesdimension, fuktkvot och temperaturnivå har betydelse för impregneringsresultatet. Totalt sett fanns det fler missar i planken än i bräderna. Plank och bräder uppvisar dessutom något olika beteende: för bräder är resultatet mera tydligt vilket även framkom vid multivariat dataanalys (MVDA) på medelvärdesnivå: högre temperatur och högre fuktkvot visar minst impregneringsmissar hos brädgrupperna. För plankgrupper erhölls överhuvudtaget inga MVDA-modeller. Även för plank hade den högre temperaturen i medel bättre impregneringsresultat. Sambandet hög fuktkvot och god impregnerbarhet är inte lika tydligt för plank, möjligen att kombinationen låg temperatur och låg fuktkvot är ogynnsam.Densitetsvariationerna visade sig vara tämligen liten och inga låga/höga extremvärden fanns i försöksmaterialet. Vid MVDA framkom ändå tendenser att det hos bräder var gynnsamt ur impregneringssynpunkt med högre densitet.Kemiska analyser visar inga dramatiska omfördelningar av extraktiver under torkning som förklaring till impregneringsmissar. Detekterbara fetter och hartssyror var dock lägre i ytliga än i inre delar av splintveden troligen beroende på oxidativ förnätning av deras struktur under torkningen.Sammanfattningsvis blir tolkningen att torktemperatur, fuktkvotsintervall och virkesdimensioner har betydelse för impregneringsresultat men att det finns ett antal okända materialvariabler som har stor inverkan på resultatet på individnivå. Även om torkningsbetingelserna görs så gynnsamma som möjligt för impregnering förekommer individer som har allvarliga genomgående missar.

  • 31.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Yang, Qian
    Heat treatments of high temperature dried norway spruce boards: Saccharides and furfurals in sapwood surfaces2012In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, no 2, p. 2284-2299Article in journal (Refereed)
    Abstract [en]

    Carbohydrates that migrate to wood surfaces in sapwood during drying might influence properties such as mould susceptibility and colour. Sugars on the surface of Norway spruce boards during various heat treatments were studied. Samples (350mm×125mm×25mm) were double-stacked, facing sapwood-side outwards, and dried at 110°C to a target moisture content (MC) of 40%. Dried sub-samples (80 mm × 125 mm × 25 mm) were stacked in a similar way and further heated at 110°C and at 130°C for 12, 24, and 36 hours, respectively. Glucose, fructose, and sucrose as well as 5-hydroxymethylfurfural (HMF) and furfural in the sapwood surface layer of treated wood were analysed using HPLC (RI- and UV-detectors). Carbohydrates degraded to a lower extent at 110°C than at 130°C. Furfural and to a larger extent HMF increased with treatment period and temperature. Heat treatment led to a decrease in lightness and hue of the sapwood surface of sub-samples, while chroma increased somewhat. Furthermore, considerably faster degradation (within a few minutes) of the carbohydrates on the surface of the dried spruce boards was observed when single sub-samples were conductively hot pressed at 200°C. Treatment period and initial MC influenced the presence of the carbohydrates in wood surface as well as colour change (ΔE ab) of the hot pressed sub-samples.

  • 32.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Torniainen, Petteri
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Dagbro, Ola
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Granlund, Kurt
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Presence of water-soluble compounds in thermally modified wood: carbohydrates and furfurals2012In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, no 3, p. 3679-3689Article in journal (Refereed)
    Abstract [en]

    With thermal modification, changes in properties of wood, such as the presence of VOC and water-soluble carbohydrates, may occur. Thermal modifications under saturated steam conditions (160°C or 170°C) and superheated steam conditions (170, 185, and 212°C) were investigated by analysing the presence of water-soluble 5-(hydroxymethyl)furfural (HMF), furfural, and carbohydrates in heat-treated wood. The influence of thermal modifications on Scots pine, Norway spruce, and silver birch was also studied. Furfurals were analysed using HPLC at 280 nm, while monosaccharides and water-soluble carbohydrates were determined by GC-FID as their acetylated alditiols and, after methanolysis, as their trimethylsilylated methyl-glycosides, respectively. The amount of furfurals was larger in boards thermally modified under saturated steam conditions than those treated under superheated steam conditions. Generally, more of HMF than furfural was found in the thermally modified boards. In process water, in which saturated steam conditions had been used, furfural and only traces of HMF were found. Higher content of water-soluble carbohydrates was found in boards treated in saturated steam rather than in superheated steam. After modification in saturated steam, substantial parts of the water-soluble carbohydrates were due to monosaccharides, but only traces of monosaccharides were found in boards treated under superheated steam conditions.

  • 33. Ahmed, Sheikh Ali
    et al.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Uneven distribution of preservative in kiln-dried sapwood lumber of Scots pine: Impact of wood structure and resin allocation2012In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 66, no 2, p. 251-258Article in journal (Refereed)
    Abstract [en]

    Scots pine (Pinus sylvestris L.) sapwood lumber was collected after kiln drying and preservative treatment with Celcure AC 800 (a copper-amine wood preservative). Distribution of the preservative throughout the lumber was visually examined. Not all, but some samples showed specific localized areas without any preservative distribution throughout their entire length. Those samples were assessed further for anatomical properties, specifically in impregnated and unimpregnated areas. Additional study was conducted on the morphological nature and redistribution of lipophilic extractives using three different histochemical staining methods. Intrinsic wood properties – especially the frequency of axial resin canals and the percentage of canals blocked – were found to be responsible for the irregular distribution of the preservative. Furthermore, the inability to create continuous and frequent interstitial spaces due to the collapse of thin-walled ray cells throughout the lumber resulted in uneven distribution of preservatives. Staining techniques were useful to localize places with more or less abundance of extractives (e.g., fats) in impregnated and unimpregnated wood, which varied considerably. Histochemical observations revealed information pertaining to the kiln dry specific distribution and redistribution of extractives between the areas. Moreover, resin reallocation and modification in ray parenchyma and resin canals induced by kiln drying would be another reason for the impregnation anomalies.

  • 34.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sidorova, Ekaterina
    SP Technical Research Institute of Sweden.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Influence of heat transferring media on durability of thermally modified wood2011In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 6, no 1, p. 356-372Article in journal (Refereed)
    Abstract [en]

    Studies on the durability and dimensional stability of a series of hardwoods and softwoods after thermal modification in vegetable oils and in steam atmospheres have been performed. Mass loss after exposure to Coniophora puteana (BAM Ebw. 15) for 16 weeks was very low for European birch, European aspen, Norway spruce, and Scots pine thermally modified in a linseed oil product with preservative (for 1 hour at 200 degrees C). Fairly low mass losses were obtained for wood thermally modified in linseed-, tung-and rapeseed oil, and losses were related to the wood species. Low mass loss during rot test was also found for Norway spruce and Scots pine modified in saturated steam at 180 degrees C. Water absorption of pine and aspen was reduced by the thermal treatments and the extent of reduction was dependent on wood species and thermal modification method. Thermally modified aspen was stable during cycling climate tests, whereas pine showed considerable cracking when modified under superheated steam conditions (Thermo D). At lower modification temperature (180 degrees C) an increase in mass after modification in rapeseed oil of spruce, aspen and sapwood as well as heartwood of pine was observed, whereas at high temperature (240 degrees C) a mass loss could be found. Oil absorption in room tempered oil after thermal modification in oil was high for the more permeable aspen and pine (sapwood).

  • 35.
    Sehlstedt-Persson, Margot
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Wamming, Thomas
    SP Trätek.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Ahmed, Sheikh Ali
    Modern torknings inverkan på impregnerbarhet i furusplint: Förstudie2011Report (Other academic)
    Abstract [sv]

    Under senare år rapporteras i Sverige för vissa impregneringsmedel en kraftig ökning av antalet underkända prov och då speciellt för kopparbaserade vattenlösliga medel. På några års sikt, när konsekvenserna av impregneringsmissar blir synliga hos slutanvändaren genom att rötskadat virke måste bytas ut, beräknas kostnaderna kunna uppgå till en halv miljard årligen. Orsakerna till inträngningsproblem diskuteras och en av många teorier är att virkestorkningen är en av huvudorsakerna. Målet med denna förstudie har varit att identifiera relevanta process- och materialvariabler som misstänks inverka på impregnerbarheten i furusplint. Resultat från impregneringsförsöken i denna förstudie visar att fuktkvotsnivån i bräder efter torkning är viktig för impregneringsresultatet. Bäst inträngning erhölls vid högre fuktkvotsnivåer än vad som vanligen används vid anläggningarna idag: i fuktkvotsintervallet 20-25 % var andelen missar lägst medan andelen missar ökade påtagligt vid sjunkande fuktkvot. En rekommendation är att inte övertorka virke som ska impregneras. Detta är vanligt speciellt vid torkning av tunna dimensioner i äldre brädkanaler.Resultat från denna förstudie sammanfattas enligt följande•Inverkan av fuktkvotsnivå vid impregnering är viktig. Bäst inträngning i bräder erhölls i fuktkvotsintervallet 20-25 %, dvs. vid högre fuktkvot än vad som vanligen görs medan missarna ökade påtagligt vid sjunkande fuktkvot. •Resultaten pekar på att splintvedsdensiteten tycks spela roll för impregnerbarheten: högre densitet tenderar att vara bättre ur impregneringssynpunkt. •Olika typer av impregneringsmissar noteras. Vissa typer har en tydlig koppling till vedanatomiska detaljer medan andra missar kopplas till process och yttre form.•Anrikning av näring mot splintvedsytor som sker vid forcerad torkning kan i vissa fall ha försvårat inträngning av träskyddsmedel.•Vedanatomiska studier visar att– axiella kådkanaler sannolikt spelar en viktig roll för inträngning av träskyddsmedel– parenkymcellers hartsinnehåll i splintved kan blockera inträngning via märgstrålar•Tomografering indikerar att hög splintvedsdensitet är gynnsamt för inträngning av träskyddsmedel. Detta överensstämmer med iakttagelsen att axiella hartskanaler är viktiga för inträngning av träskyddsmedel eftersom axiella hartskanaler främst finns i sommarved och hög densitet förknippas med hög sommarvedsandel. •Kemisk analys indikerar att lokal skillnad i extraktivämneshalt kan vara en av förklaringarna till impregneringsmiss i splintved. •I fortsatta studier är tomografering ett kraftfullt analysverktyg för att se inträngningsmissar i rått tillstånd.

  • 36.
    Sehlstedt-Persson, Margot
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Wamming, Thomas
    SP Träteknik.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Mold growth on sapwood boards exposed outdoors: the impact of wood drying2011In: Forest products journal, ISSN 0015-7473, Vol. 61, no 2, p. 170-179Article in journal (Refereed)
    Abstract [en]

    Mold growth on dried Norway spruce and Scots pine sapwood boards was investigated in an accelerated outdoor field test for 96 days. The boards were dried using three different methods of stacking: single stacking, double stacking with the sapwood sides in each pair facing toward each other, and double stacking with sapwood sides facing outward. Drying was performed at three temperatures: 25ºC, corresponding to air drying, and kiln drying at 70ºC and 110ºC. The degree of mold growth was visually assessed on both sides of each board. On average, pine boards showed a higher level of mold growth than the spruce boards. The highest average level of mold growth was found on the boards kiln dried at 708C, whereas the air-dried boards and the boards kiln dried at 110ºC showed considerably less mold growth. Stacking the boards during drying had a large impact on mold susceptibility of the sapwood. This study confirmed that, during the drying process, it is possible to direct the migration of nutrients in sapwood toward one chosen side of each board by double stacking; the opposite side leaches out, which has a great impact on surface mold growth. Chemical analyses of monosaccharide sugar gradients beneath the boards’ surfaces confirmed the results.

  • 37.
    Dagbro, Ola
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Torniainen, Petteri
    Department of Forest Products, Swedish University of Agricultural Sciences, Uppsala.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Colour responses from wood, thermally modified in superheated steam and pressurized steam atmospheres2010In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 5, no 3, p. 211-219Article in journal (Refereed)
    Abstract [en]

    In this study, two different methods were used to produce thermally modified wood. One was carried out in a typical kiln drying chamber using superheated steam (SS) and the other used pressurized steam in an autoclave cylinder (PS). Overall, both processes followed the same principles and the wood was not treated with any chemicals. Two wood species were studied, Scots pine (Pinus sylvestris) and Norway spruce (Picea abies). Treatments in the autoclave were carried out under pressure using temperatures of 160°C, 170°C and 180°C. Temperatures of 190°C and 212°C were used in treatments in the chamber at normal air pressure. The colour was measured using L*C*H colour space. Results for both species showed that similar L* (lightness) can be reached at lower (20-308C) temperatures using PS compared with SS treatment. The hue angle of PS-treated wood was smaller than that of SS-treated wood. No significant difference in C* (chroma) was detected. The difference in E value between PS- and SS-treated wood was smaller for Norway spruce than for Scots pine. The residual moisture content was about 10% higher in wood treated by the PS process compared with the SS process

  • 38.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Colour stabilization of heat modified Norway spruce exposed to out-door conditions2010In: Proceedings, 11th International IUFRO Wood Drying Conference: [... in Skellefteå, Sweden, January 18 - 22, 2010 ... the theme of the conference was "Recent Advances in the Field of Wood Drying"] / [ed] Tom Morén; Lena Antti; Margot Sehlstedt-Persson, Luleå: Luleå tekniska universitet, 2010, p. 265-268Conference paper (Refereed)
    Abstract [en]

    Wood boards from Norway spruce (300 mmx125mmx10mm) were heat modified in a pilot chamber corresponding to Thermowood-D quality. The surface of boards was sprayed with diluted solutions of ferrous sulphate alone or in combination with subsequent spraying of a 30% solution of hydrogen peroxide. The boards were exposed to outdoor conditions during summer 2009 (45o facing south). Colour coordinates were measured using a colorimeter.Only small changes in colour of boards were observed directly after the surface treatments. Lightness increased for boards with no surface treatments during out-door exposure (seven weeks). Increase in lightness was delayed when ferrous sulphate was applied to the board. Lightness was essentially unchanged during the out-door exposure period when ferrous sulphate and hydrogen peroxide was used to modify the wood surface (at low hydrogen peroxide charge a small increase of lightness was, however, observed). Chroma decreased for boards with surface treatments but levelled out after a couple of weeks. On the other hand a decrease in chroma of boards with no surface treatments started after about four weeks exposure. Hue increased for all the boards until the fourth week. After that hue of untreated boards and boards treated with both ferrous sulphate and hydrogen peroxide continue to increase.

  • 39.
    Sehlstedt-Persson, Margot
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Natural durability and phenolic content in dried Scots Pine heartwood2010In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 5, no 2, p. 1126-1142Article in journal (Refereed)
    Abstract [en]

    The durability of Scots pine heartwood has previously been shown to be affected by the industrial drying process of sawn lumber. The durability of heartwood from boards dried at temperatures between 20°C-110°C was studied by measuring the mass loss in a decay test with a brown rot fungus (Coniophora puteana), and the concentration of total phenolics was measured according to the Folin-Ciocalteu (FC) assay. The relation between mass loss and phenolics in dried heartwood showed a weaker negative correlation at lower levels of phenolics as compared to the strong relationship found in a study on heartwood from standing Scots pine trees. Mass loss in dried heartwood showed a weak negative correlation to density. Heating of extractives-rich green sawdust under moist conditions resulted in a reduction of phenolics with temperature up to 180 oC and with increasing time. The concentration of phenolics in heated, green sawdust was higher in extractives-rich pine heartwood than in heartwood with a normal extractives content.

  • 40.
    Sehlstedt-Persson, Margot
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Wamming, Thomas
    SP Trätek.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Processanpassning för funktionsbeständiga träprodukter: Vilken roll spelar torkningen för mögelpåväxt på brädor i utomhusprodukter ovan mark?2010Report (Other academic)
    Abstract [sv]

    Torkningsprocessens inverkan på mögelbenägenhet hos råspont i utomhusanvändning har studerats. Brädor postat som sidoutbyte från vinterfällt virke har använts i försöken. De torkningar som utvärderats är friluftstorkning, artificiell torkning vid 70°C samt en HT (högtemperatur) torkning vid 110°C. Som utvärderingsmetod har ett forcerat mögeltest utomhus använts. Mögelpåväxten har därefter bedömts visuellt på provbrädornas båda sidor.I projektansökan ingick enbart undersökning av träslaget gran men i försöken har även furu ingått. Anledningen till denna utökning av projektet med träslaget furu är att projektutförarna ville vara säkra på att effekter av olika variabler skulle bli tydliga nog för utvärdering av torkningens inverkan, då furu på grund av sin högre näringshalt i splintveden förväntas vara mer mögelbenäget än gran. Projektets arbetshypoteser har varit följande:•en anrikning av näringsämnen sker i gransplint under torkning•näringsanrikning mot ytan kan styras under torkning•den av torkningen påverkade näringsanrikningen i splintved mot ytan har betydelse för virkesytans mögelbenägenhet •den näringsanrikade zonen kan påverkas termiskt genom värmning och göras mindre ”aptitlig” för mögelsvampar I projektets inledande del undersöktes om en näringsgradient finns i den torkade virkesytan även i gransplint på samma sätt som det väl dokumenterat finns i furu. Denna anrikning av kolhydrater påverkas i hög grad av hur snabbt, ”hårt” torkningen görs i den inledande kapillära torkningsfasen. Den inledande kemiska kolhydratanalys av torkad gransplint som gjordes bekräftade att en anrikning av kolhydrater sker även i gransplint under torkning. På det artificiellt torkade provmaterialet har ur varje prov gjorts ett avkap efter torkning. På dessa avkap har effekten på mögelbenägenhet av två olika efterbehandlingar genom värmning i tork undersökts: 3 timmars torr värmning upp till 90°C samt 3 timmars värmning med mättad vattenånga upp till 90°C.En intressant idé dök upp under projektets inledande planering med ursprung i iakttagelsen att synlig mögelpåväxt inte tycks finnas på ytor där strön legat an mot virket och blockerat fuktavgången. Idén bygger på hypotesen att näringsanrikning i splintved under torkning är möjlig att styra mot en av brädornas flatsidor genom dubbelläggning av brädor under torkning. Vid efterföljande hyvling av brädor till råspont väljs den näringsurlakade flatsidan som utsida och den näringsanrikade sidan och kanterna bearbetas. Inledande försök på små prover av furusplint bekräftade hypotesen att näringsanrikning kan styras mot en sida av brädan. Därför togs i projektet beslutet att undersöka effekterna på mögelbenägenhet av olika kombinationer av dubbelläggning av virke under torkning. Eftersom idén vid utvärdering visade mycket lovande resultat har under projektets gång en patentansökan av metoden, att genom dubbelläggning av virke under torkning styra näringsvandringen i splintved mot vald yta och på så sätt åstadkomma virkesytor med minskad mögelbenägenhet inlämnats till PRV den 2010 02 17.Resultaten sammanfattas under följande rubrikerAnrikning av näringsämnen i gransplintI projektet konstateras att •kemisk kolhydratanalys av torkad gransplint bekräftar att en näringsanrikning sker även i gransplint under torkning•denna anrikade ”front” även kan bekräftas visuelltStyrning av näringsanrikning mot ytan under torkningI projektet konstateras att •näringsanrikning i splintved kan styras mot en flatsida under torkning genom dubbelläggning•mest näring i ytan finns i splintsidor som lagts utåt i dubbelläggning•minst näring i ytan finns i märgsidor som lagts mot varandra under torkningMögelbenägenhet hos torkade splintvedsytorI projektet konstateras att •den under torkning anrikade näringen mot splintvedsytor har stor betydelse för virkesytans mögelbenägenhet •furusplint är mer mögelbenäget än gransplint•HT-torkning vid 110°C visar låg mögelgrad i gran vid både enkel- och dubbelläggning •friluftstorkad gran visar låg mögelgrad vid enkelläggning•forcerad torkning vid 70°C uppvisar mest mögelpåväxt i både gran och furu•genom dubbelläggning av gran med ”rätt” flatsidor mot varandra kan ytor med låg mögelpåväxt åstadkommas även vid 70°C•det forcerade mögeltestet utomhus som använts som utvärderingsmetod har fungerat utmärkt Efterbehandling i tork genom torrvärmning och ångvärmningI projektet konstateras att •för gran torkat vid 70°C ger både ånga och torrvärmning signifikant lägre mögelpåväxt jämfört med ej efterbehandlat•i furu ger dessa efterbehandlingar inte signifikant lägre mögelpåväxt Inverkan på mögelbenägenhet av vankant och maskinskador i virket I projektet konstateras att •förekomst av vankant och maskinskador i virket ökar mögelbenägenheten på splintsidan•även brädor med mycket vankant/maskinskador som dubbelläggs kan ha låg mögelbenägenhet på motlagda flatsidor

  • 41. Pantze, Anna
    et al.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Westermark, Ulla
    Esterification of carboxylic acids on cellulosic material: solid state reactions2008In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 62, no 2, p. 136-141Article in journal (Refereed)
    Abstract [en]

    In the present work, the formation of ester linkages in cellulosic materials during drying and heating was addressed. The results indicated that direct ester formation, without anhydride intermediate, occurs between carboxylic acids of suitable structure and cellulosic hydroxyls at 180 degrees C, even after reaction times as short as 5 min. The 2(R)-hydroxybutyric acid is most effective in ester formation, followed by 2-ketobutyric acid and 3-hydroxybutyric acid. Hexanoic acid is less effective and veratric acid produces no esters at all. At lower temperatures, 2-ketobutyric acid is the most reactive compound. One conclusion is that a hydroxyl or keto group in alpha position of the carboxylic acids favours ester formation. Another finding is that three pyrrolidine structures are produced after esterification and aminolysis of 2-ketobutyric acid. One of the structures indicates that 2-ketobutyric acid is reactive in two positions and could therefore be a potential cross-linker. A critical parameter for ester formation is pH, and the results indicate that pH < 2 strongly favours esterification, whereas almost no esters are produced at pH > 5-6. All experiments were performed in a solid-state model system (on cellulosic filter paper) with low moisture content. Esterification of five carboxylic acids was studied. Samples were heated constantly at 180 degrees C for 5 min or gradually from 22 degrees C to 180 degrees C over periods ranging from 5 to 45 min. Quantitative analysis of ester formation between the monocarboxylic acids and the hydroxyl groups of cellulose was performed by means of aminolysis and gas chromatography.

  • 42.
    Sehlstedt-Persson, Margot
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Wamming, Thomas
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Skog, Johan
    Processanpassning för funktionsbeständiga träprodukter: vilken roll spelar torkningen för virkets beständighet i utomhusprodukter ovan mark?2008Report (Other academic)
    Abstract [sv]

    Torkningsprocessens inverkan på beständigheten hos centrumsågat furuvirke 50x125 mm har studerats. Som utvärderingsmetod har röttester med brunrötesvampen Coniophora puteana (källarsvamp) gjorts på prov från splintved samt inre och yttre kärnved. Stor massförlust efter röttest visar på dålig beständighet. De torkningar som utvärderats är lufttorkning, artificiell torkning vid 70°C och 90°C samt en högtemperaturtorkning vid 110°C. För 70°C och 90°C torkningarna har två principscheman använts: ett med snabb temperaturökning i virket tidigt i torkningen och ett där virkestemperaturen når maxtemp i ett betydligt senare skede. Även inverkan av ångkonditionering i slutet av torkningen har utvärderats. Skanning med UV-ljus har utförts på virkestvärsnitt från samtliga torkningar för att undersöka hur UV-fluorescens av pinosylvin i kärnved påverkas av torkning samt om denna skanningsmetod kan användas för att prediktera massförlust (beständighet). Kapillärupptag av vatten i splint från de olika torkningarna har studerats i tomograf. Totalhalten av fenoliska ämnen i torkad kärnved, som av andra forskare visats ha stor betydelse för rötbeständighet mot källarsvamp på färsk ved, har bestämts med Folin-Ciocalteu (FC) metoden. Inledningsvis gjordes två serier med homogent spån (från virke som ej ingår i torkförsöken) som värmdes vid olika temperaturer. När resultaten från röttesterna från det torkade försöksvirket var kända utvaldes provplankor med lägst och högst massförlust ut från samtliga torkningsserier och analyserades med avseende på extraktivämneshalt och totalfenolhalt enligt FC-metoden. Resultaten sammanfattas under följande rubriker Råvaran Vid röttest med källarsvamp på torkat furuvirke konstateras Splintved ha betydligt sämre rötbeständighet än kärnved. Ingen skillnad i rötbeständighet mellan inre och yttre kärnved. Stor spridning i rötbeständighet mellan olika plankindivider men även inom en och samma planka i längdled. Svag indikation att högre veddensitet har bättre beständighet. Trolig förklaring är extraktivämneshalt. Totalfenolhalten vara högre i kärnved med hög extraktivämneshalt jämfört med låg extraktivämneshalt. Totalfenolhalten i spån från fet kärnved minskar vid värmning över 40°C upp till 110°C. Högre totalfenolhalt indikera lägre massförlust även i torkad furukärna. Torkning Vid beständighetstest med källarsvamp på furuvirke torkat vid olika temperaturer konstateras Splintved ha betydligt större massförlust än kärnved i samtliga torkningar Kärnved från lufttorkat virke ha minst massförlust vid röttest. Splintved och kärnved från virke torkat vid 90°C med snabb temperaturökning i virket ha störst massförlust vid röttest. Ångkonditionering efter torkning öka massförlusten vid röttest i furusplint. UV-skanning Vid UV-skanning av virkestvärsnitt från samtliga torkningar konstateras att färgkomponenter kan separera: - Virke torkat vid 20°C och 70°C från virke torkat vid 90°C och 110°C. - Inre kärnved från yttre kärnved och splintved. att signalerna måste kalibreras då möjligen även inslag av "vanlig färg" iveden ingår i signalerna. Kapillärförsök Då ingen fullständig utvärdering av tidsskäl hunnit göras konstateras här endast att Skillnader mellan olika torkningar kan ses i fuktgradienternas utseende i axiell led efter 6 dygns uppsugning. En tänkbar förklaring kan vara övergångar mellan olika mekanismer för vattenupptagning som har att göra med torkningssätt och temperatur, exempelvis söndertrasade pormembran i det artificiellt torkade virket eller förändrade vätningsegenskaper i veden vid högre temperatur. Projektets målsättning att formulera rekommendationer för beständighetsanpassad torkning av furuvirke sammanfattas enligt följande: Den kritiska parametern under torkningsprocessen för beständigheten i kärnved är virkestemperaturen tidigt i torkningen. För artificiell torkning i virkestork bör därför torkstyrningen anpassas så att virkestemperaturen hålls nere tidigt i torkningen när fuktkvoten är hög. För rötbeständighet i splintved är ångkonditionering efter torkning mindre lämplig.

  • 43.
    Nordstierna, Lars
    et al.
    Industrial NMR Centre and Division of Physical Chemistry, Department of Chemistry, Royal Institute of Technology, Stockholm.
    Lande, Stig
    Kebony ASA, Porsgrunn.
    Westin, Mats
    SP Technical Research Institute of Sweden, Borås.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Furó, István
    Industrial NMR Centre and Division of Physical Chemistry, Department of Chemistry, Royal Institute of Technology, Stockholm.
    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. Pantze, Anna
    et al.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Westermark, Ulla
    A model system to study esterification reactions in cellulosic or lignocellulosic material2007In: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 33, no 4, p. 177-183Article in journal (Refereed)
    Abstract [en]

    The formation of natural ester cross-linkages in cellulosic or lignocellulosic composite materials during drying and heating is of interest for the production of paper and of wood composite boards and in giving cotton materials improved characteristics. A model system has been developed to study quantitatively the esterification of cellulosic material during drying and heating when solid-state conditions can be said to predominate. In the experiments, hexanoic acid and 3-hydroxybutyric acid were added to ordinary filter paper. Moisture content was adjusted, and samples were heated to temperatures ranging from 85 degrees C to 180 degrees C for between 15 and 45 minutes. Quantitative analysis of ester,formation, in this case between the monocarboxylic acids and the cellulose's hydroxyl groups, was performed using aminolysis/gas chromatography. The 3-hydroxybutyric acid was surprising v effective in ester formation. The results indicate that direct esterification of monocarboxylic acid can be an important reaction in lignocellulosic material at elevated temperatures.

  • 45. Sundqvist, Bror
    et al.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Westermark, Ulla
    Determination of formic-acid and acetic acid concentrations formed during hydrothermal treatment of birch wood and its relation to colour, strength and hardness2006In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 40, no 7, p. 549-561Article in journal (Refereed)
    Abstract [en]

    Formation of benzyl esters from acetic and formic acids during heat treatment of birch at 160-200°C has been studied by gas chromatography. High concentrations of formic and acetic acids formed by the wood itself during hydrothermal treatment were found. The concentrations of acids increased with both treatment time and temperature. The maximum formic- and acetic acid concentrations found at 180°C and after 4 h of treatment performed in this work were 1.1 and 7.2%, based on dry-weight wood, respectively. The treated wood material was characterised by mechanical testing [bending tests perpendicular to the grain, modulus of rupture, modulus of elasticity, Brinell hardness, impact bending and colour measurements (CIE colour space)]. The experiments, where high concentration of acids was formed, showed severe losses in mass and mechanical strength. Indications of possible enhanced mechanical properties for the treated, compared with untreated birch wood were found around 180-200°C at short treatment times. This paper discusses possible degradation reactions coupled with the colour and mechanical properties in relation to acid formation, and suggestions for process optimisations.

  • 46.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Westermark, Ulla
    Backlund, Ulrika
    Metso, Sundsvall.
    Halvarsson, Sören
    Mittuniversitetet.
    Environmentally friendly process for high density fibreboards2006Conference paper (Other academic)
    Abstract [en]

    Urea-formaldehyde (UF) resin is a common binder in many fibre- and particleboards today. However, formaldehyde is a fairly reactive compound with many negative affects on health and environment. This paper describes a process to make thin high density fibreboards without use of conventional resin such as UF. Initially we found that wood particles such as ones used in particle board had, when activated with hydrogen peroxide and iron catalyst, self-bonding capability when hot-pressed into boards. Low swelling board, although at somewhat higher density than conventional glued ones, could be formed by pressing activated wood particles at 170 oC in a laboratory press. We found that the activation technique was applicable to dry or semi-dry board processes and was considered to be well suited for fibreboards from refined wood fibers especially as their specific (contact) area is high. Activated wood fibres were produced at Metso Panelboards Pilot-refiner in Sundsvall and mats were also formed and pressed into boards 50x60 cm2 at fairly conventional pressing conditions. At a hydrogen peroxide charge of 4% boards made from birch fibres with good mechanical properties (in terms of bending strength and internal bonding) were produced. Thickness swelling in water was low (TS24h., 15-20%). At lower hydrogen peroxide charges (<2%) the swelling was higher. Development of the process to also include other wood species than birch is in our interest. Furthermore, properties of the boards were strongly dependent on the moisture content of fibres; at low moisture content (MC<8%) thickness swelling increased. We see a high potential in the process as the glue-free technique is estimated to reduce production cost of boards as well as give environmental advantages.

  • 47. Pantze, Anna
    et al.
    Westermark, Ulla
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Formation of ester cross linkage in lignocellulosic materials during drying and heating2005Conference paper (Other academic)
  • 48.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Ikeda, Tsutomu
    Wood Chemistry Laboratory.
    Kishimoto, Takao
    Wood Chemistry Laboratory.
    Magara, Kengo
    Wood Chemistry Laboratory.
    Matsumoto, Yuji
    Wood Chemistry Laboratory.
    Hosoya, Shuji
    Wood Chemistry Laboratory.
    Isolation of lignin-carbohydrate bonds in wood: model experiments and preliminary application to pine wood2004In: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 50, no 2, p. 141-150Article in journal (Refereed)
    Abstract [en]

    A novel method for analysis of benzylic ether type lignin-carbohydrate bonds has been developed by using model compounds. Four diastereomers of model compound 3-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)-3-(methyl -d-glucopyranoside-6-O-yl)-1-propanol (GGMGP), were ozonized in acetic acid/water/methanol 16:3:1 for 1h at 0°C. The product from ozonation of each diastereomer was saponified and the corresponding -etherified tetronic acid (TAMGP) was isolated using ion exchange chromatography. Minor amounts of methyl -d-glucopyranoside (MGP) and small amounts of a gluconic acid etherified with tetronic acid (TAGLCA), tetronic acid, gluconic acid, and glyceric acid were detected in the product mixture of ozonated benzylic ether type model compounds. The results suggest that a benzyl ether bond between lignin and carbohydrate is rather stable during the ozone treatment. Acid treatments with sulfuric acid or trifluoroacetic acid of the derived TAMGP led to cleavage of the glucosidic bond but only a small amount of products (tetronic acid and glucose) resulting from cleavage of the -ether bond were formed. The successful chemical treatments were used for studies of benzylic ether bonds in Japanese red pine. The results suggest the presence of benzylic ether bonds to polysaccharides in the wood.

  • 49.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Westermark, Ulla
    Auto-adhesive bonding by oxidative treatment of wood2003In: Proceedings of the 12th International Symposium on Wood and Pulping Chemistry: University of Wisconsin-Madison, Department of Forest Ecology and Management, June 9 - 12, 2003, Madison, Wisconsin, USA, Madison, Wis, 2003, p. 365-368Conference paper (Refereed)
  • 50. Magara, Kengo
    et al.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hosoya, Shuji
    Reduction of chloroform emission from hypochlorite-bleaching process2003In: Kami Pa Gikyoshi, ISSN 0022-815X, Vol. 57, no 9, p. 76-83Article in journal (Refereed)
    Abstract [en]

    Chloroform was readily converted to formic acid through the nucleophilic attack of hydroxyl anion under the certain reaction conditions (pH>12, temp.>°C). When guaiacol was reacted with hypochlorite at such reaction conditions, the generation of chloroform was almost completely reduced. Successful reduction of the chloroform generation was also observed in alkaline hypochlorite bleaching of kraft pulps and DIP without any loss in pulp quality. Even when the hypochlorite bleaching was carried out under the open system (no sealing of the reaction vessel), nearly 90% of the generated chloroform was converted to formic acid.

12 1 - 50 of 64
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