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  • 1.
    Ahmed, Sheikh Ali
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sehlstedt-Persson, Margot
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Morén, Tom
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Uneven distribution of preservative in kiln-dried sapwood lumber of Scots pine: Impact of wood structure and resin allocation2012Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 66, nr 2, s. 251-258Artikel i tidskrift (Refereegranskat)
    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.

  • 2.
    Bandura, Iryna
    et al.
    Tavria State Agrotechnological University, Department of technology of processi ng and storage of agricultural products.
    Myronycheva, Olena
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Assessment of Raw Plant material and Substrate for Efficient production of Oyster Mushrooms (Pleurotusostreatus (Jacq.) P. Kumm.)2016Ingår i: Ochrana drevín a dreva 2016: zborník recenzovaných vedeckých prác a abstraktov / [ed] Pavol Hlaváč , Zuzana Vidholdová, Zvolen: Technická univerzita vo Zvolene , 2016, s. 27-33Konferensbidrag (Refereegranskat)
    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.

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    oyster
  • 3.
    Bandura, Iryna
    et al.
    Tavria State Agrotechnological University .
    Myronycheva, Olena
    Tavria State Agrotechnological University .
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    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 production2017Ingår i: 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, s. 41-43Konferensbidrag (Refereegranskat)
    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.

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  • 4.
    Borko, Domen
    et al.
    Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia.
    Scharf, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Lin, Chia-Feng
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Humar, Miha
    Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Jones, Dennis
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik. Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia.
    The potential of citric acid and glucose enhancing the reaction of wood with bicine and tricine2024Ingår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To improve the resistance of wood to biological decay the Maillard reaction between introduced amines and wood cell-wall polymers can be utilised. However, initial studies in wood modification showed almost complete leaching of bicine and tricine from treated wood and the loss of beneficial effects. The objective of this study was to assess whether possible reactions of bicine or tricine with wood could be further enhanced and reaction products stabilised through the addition of glucose and/or citric acid. Thus, Scots pine sapwood specimens were impregnated with tricine or bicine, with or without glucose and citric acid, and then heated to a temperature of 160°C. The dimensional stability, degree of chemical leaching and mechanical properties were assessed. Overall, it was concluded that neither the presence of glucose nor citric acid did appear to enhance the reactivity of tricine or bicine. Anti-swelling efficiency (ASE) of 50% was observed for combined treatments of bicine/tricine and citric acid but the leaching resistance originated mainly from citric acid and glucose, with no indication for the retention of bicine or tricine. The presence of citric acid led to a strongly reduced modulus of rupture. 

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  • 5.
    Brunow, G.
    et al.
    Department of Chemistry, University of Helsinki, Helsinki, Finland.
    Karlsson, Olov
    Department of Organic Chemistry, Chalmers University of Technology and University of Göteborg, Göteborg, Sweden.
    Lundquist, K.
    Department of Organic Chemistry, Chalmers University of Technology and University of Göteborg, Göteborg, Sweden.
    Sipilä, J.
    Department of Chemistry, University of Helsinki, Helsinki, Finland.
    On the distribution of the diastereomers of the structural elements in lignins: the steric course of reactions mimicking lignin biosynthesis1993Ingår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 27, nr 4, s. 281-286Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Stereochemical studies on the formation of the diastereomers of arylglycerol-β-aryl ether structures during lignin biosynthesis have been carried out with model compounds. The addition of water to quinone methides of the β-syringyl ether type gives arylglycerol β-syringyl ethers with a predominance of the erythro isomer when the pH of the medium is low. Since erythro forms of arylglycerol β-syringyl ethers are prevalent in hardwood lignins, this indicates that the pH of the medium in which lignin biosynthesis occurs is lower than has been assumed until now. Equilibration studies with non-phenolic model compounds of the arylglycerolβ-guaiacyl ether and β-syringyl ether types under acidolysis conditions indicate that the erythro predominance observed in the syringyl ethers in lignins does not correspond to equilibrium conditions. A remarkable resistance to acidolysis is observed in the model compounds of etherified syringylglycerol β-syringyl ether type.

  • 6.
    Chen, Tingjie
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    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 tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Optimizing Refining Conditions of Pinus massoniana Cellulose Fibers for Improving the Mechanical Properties of Ultra-Low Density Plant Fiber  Composite (ULD_UFC)2017Ingår i: BioResources, E-ISSN 1930-2126, Vol. 12, nr 1, s. 8-18Artikel i tidskrift (Refereegranskat)
    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.

  • 7.
    Chen, Tingjie
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    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 tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    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 Fibers2016Ingår i: BioResources, E-ISSN 1930-2126, Vol. 11, nr 3, s. 7839-7848Artikel i tidskrift (Refereegranskat)
    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.

  • 8.
    Chen, Tingjie
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    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 tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    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 Treatment2016Ingår i: BioResources, E-ISSN 1930-2126, Vol. 11, nr 4, s. 8558-8569Artikel i tidskrift (Refereegranskat)
    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.

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  • 9.
    Cristescu, Carmen
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Changes in content of furfurals and phenols in self-bonded laminated boards2013Ingår i: BioResources, E-ISSN 1930-2126, Vol. 8, nr 3, s. 4056-4071Artikel i tidskrift (Refereegranskat)
    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

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    FULLTEXT01
  • 10.
    Cristescu, Carmen
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Ekevad, Mats
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Influence of pressing parameters on mechanical and physical properties of self-bonded laminated beech boards2015Ingår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 10, nr 2, s. 205-214Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Five-ply self-bonded boards were obtained by pressing beech veneers parallel to the grain without additional adhesives, steam or pre-treatment. Fifteen different combinations of pressing parameters were tested, including temperature (200°C, 225°C and 250°C), pressure (4, 5 and 6 MPa) and pressing time (240, 300 and 360 seconds). Due to severe pressing conditions, the new product showed a higher density and different properties compared to a conventionally glued laminated wooden board. The self-bonding quality was assessed through dry shear strength tests, through a three-point bending test and a water-soaking test at 20°C. The dimensions in the cross section of the boards were measured after soaking in water. Results show that the choice of pressing parameters affects all the mechanical and physical properties tested. A statistical analysis revealed that the pressing temperature is the most influential parameter. Boards pressed at 200°C delaminated rapidly in water, whereas boards pressed at 225°C delaminated only at core-positioned layers after 48 hours and boards pressed at 250°C did not delaminate at all in water. Compared to panels pressed at lower temperatures, boards pressed at 250°C had the highest density, a higher shear and bending strength and a lower water absorption.

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    fulltext
  • 11.
    Cristescu, Carmen
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Could colour predict hardness of hot-ptressed self-laminated beech boards2015Ingår i: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 11, nr 4, s. 150-156Artikel i tidskrift (Refereegranskat)
    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.

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  • 12.
    Cristescu, Carmen
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Markers of quality in self-bonded beech boards2017Konferensbidrag (Refereegranskat)
    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.

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  • 13.
    Dagbro, Ola
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Torniainen, Petteri
    Department of Forest Products, Swedish University of Agricultural Sciences, Uppsala.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Morén, Tom
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Colour responses from wood, thermally modified in superheated steam and pressurized steam atmospheres2010Ingår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 5, nr 3, s. 211-219Artikel i tidskrift (Refereegranskat)
    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

  • 14.
    Elustondo, Diego
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Myronycheva, Olena
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sundqvist, Bror
    SP Technical Research Institute of Sweden.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Localized Wood Surface Modification: Part I: Method Characterization2016Ingår i: BioResources, E-ISSN 1930-2126, Vol. 12, nr 1, s. 283-295Artikel i tidskrift (Refereegranskat)
    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.

  • 15.
    Elustondo, Diego
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sidorova, Ekaterina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Development of method for surface modification of wood2015Ingår i: 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, s. 137-140Konferensbidrag (Refereegranskat)
    Abstract [en]

    This study concerns the development of a method for surface modification based on the hot-and-cold bath process. In the experiments the wooden boards were first heated in an oven and after that they were immediately soaked in a cold chemical solution. This procedure allowed the chemicals to penetrate partially into the wood without using pressure equipment. In this study copper, furfuryl alcohol and phenol formaldehyde based solutions were used. The impregnation resulted in modified layers below the wood surfaces representing a trade- off between the full-bulk modification and surface coating of wood. It is concluded that the method can be developed further for potential industrial use to produce e.g. flooring, cladding or decking.

  • 16.
    Garskaite, Edita
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Stankeviciute, Zivile
    Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Vilnius, Lithuania.
    Aivaras, Kareiva
    Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Vilnius, Lithuania.
    Jones, Dennis
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Surface hardness and flammability of Na2SiO3 and nano-TiO2 reinforced wood composites2019Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 9, nr 48, s. 27973-27986Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The objective of this study was to explore an effect of the combined inorganic materials on the wood hardness and flame-retardancy properties in a concept of sustainable material management. Herein, the reinforcement of Scots pine (Pinus sylvestris L.) sapwood with sodium silicate and TiO2 nanoparticles via vacuum-pressure technique is reported. Pyrolysis of modified wood was studied by TG-FTIR analysis; the results showed that maximum weight loss for the modified wood was obtained at 40–50 °C lower temperatures compared to the reference untreated wood. The Gram–Schmidt profiles and spectra extracted at maxima absorption from Gram–Schmidt plots indicated chemical changes in wood–inorganic composites. SEM/EDS analysis revealed the presence of Na–O–Si solid gel within the wood-cell lumen and showed that TiO2 was homogeneously distributed within the amorphous Na–O–Si glass-forming phase to form a thin surface coating. EDS mapping further revealed the higher diffusivity of sodium into the cell wall compared to the silicon compound. The presence of amorphous sodium silicate and nano-TiO2 was additionally confirmed by XRD analysis. FTIR spectra confirmed the chemical changes in Scots pine sapwood induced by alkalization. Brinell hardness test showed that the hardness of the modified wood increased with the highest value (44% increase in hardness) obtained for 10% Na2SiO3–nTiO2 modified wood. The results showed good correlation between TG and flammability test; limiting oxygen index (LOI) values for the wood–inorganic composites increased by 9–14% compared to the untreated wood.

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  • 17.
    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 tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Kumar, Anuj
    Department of Forestry and Wood Technology, Linnaeus University.
    Development of sustainable bio-adhesives for engineered wood panels: A Review2017Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 7, nr 61, s. 38604-38630Artikel i tidskrift (Refereegranskat)
    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.

  • 18.
    Hemmilä, Venla
    et al.
    Linnaeus University, SE-351 95 Växjö, Sweden.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Modified Wood-Protein Adhesive Bondline Strength Development during Curing2014Ingår i: The seventh European Conference on Wood Modification: Book of Abstracts / [ed] Lina Nunes; Dennis Jones; Callum Hill; Holger Militz, Lissabon, 2014, s. 134-137Konferensbidrag (Refereegranskat)
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  • 19.
    Jones, Dennis
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik. Department of Forestry and Biomaterials, Czech University of Life Sciences Prague, Prague, Czech Republic.
    Lin, Chia-Feng
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Kim, Injeong
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Garskaite, Edita
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik. Department of Forestry and Biomaterials, Czech University of Life Sciences Prague, Prague, Czech Republic.
    Recent studies into improved fire retardancy of wood undertaken at Luleå University of Technology.2023Ingår i: Proceedings IRG54 Scientific Conference on Wood Protection., The International Research Group on Wood Protection , 2023, artikel-id IRG/WP 23-30784Konferensbidrag (Refereegranskat)
  • 20.
    Jones, Dennis
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik. Czech University of Life Sciences Prague, Department of Forestry and Biomaterials, 16500 Prague, Suchdol, Czech Republic.
    Lin, Chia-Feng
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Kim, Injeong
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik. Czech University of Life Sciences Prague, Department of Forestry and Biomaterials, 16500 Prague, Suchdol, Czech Republic.
    Recent studies into improving the fire retardancy of particleboards at Luleå University of Technology2023Ingår i: Proceedings of International Panel Production Symposium 2023 / [ed] Spear, M., Curling, S., Dimitriou, A, Elias, R. & Loxton, C., The BioComposite Centre, Bangor University, UK , 2023, s. 85-93Konferensbidrag (Refereegranskat)
  • 21.
    Jönsson, L.
    et al.
    Division of Biochemistry, Chemical Center, University of Lund, Lund , Sweden.
    Karlsson, Olov
    Department of Organic Chemistry, Chalmers University of Technology, University of Göteborg, Göteborg, Sweden.
    Lundquist, K.
    Department of Organic Chemistry, Chalmers University of Technology, University of Göteborg, Göteborg, Sweden.
    Nyman, P. O.
    Division of Biochemistry, Chemical Center, University of Lund, Lund , Sweden.
    Trametes versicolor ligninase: isozyme sequence homology and substrate specificity1989Ingår i: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 247, nr 1, s. 143-146Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The substrate specificity of three ligninase isozymes from the white-rot fungus Trametes versicolor has been investigated using stereochemically defined synthetic dimeric models for lignin. The isozymes have been found to attack non-phenolic β-O-4 as well as β-1 lignin model compounds. This finding confirms the classification of the isozymes from T. versicolor as ligninases. The amino-terminal residues of the three isozymes from T. versicolor have been determined using Edman degradation. Minor differences found between the sequences suggest the existence of several structural genes for ligninase in T. versicolor. Comparisons have been made with the sequences of three previously reported ligninases from Phanerochaete chrysosporium, another lignin-degrading fungus. One of the sequences from P. chrysosporium is distinctly more similar to the T. versicolor isozymes than to the other two sequences from P. chrysosporium.

  • 22.
    Jönsson, L.
    et al.
    University of Lund.
    Karlsson, Olov
    Department of Organic Chemistry, Chalmers University of Technology and University of Göteborg, Göteborg, Sweden.
    Lundquist, K.
    Department of Organic Chemistry, Chalmers University of Technology and University of Göteborg, Göteborg, Sweden.
    O., Nyman P.
    University of Lund.
    Stereospecificity in enzymic and non-enzymic oxidation of β-O-4 lignin model compounds1990Ingår i: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 276, nr 1,2, s. 45-48Artikel i tidskrift (Refereegranskat)
  • 23.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Cristescu, Carmen
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Neyses, Benedikt
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Pretreatment of veneers with hydrogen peroxide for self-bonded laminated boards2015Ingår i: 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, s. 305-310Konferensbidrag (Refereegranskat)
    Abstract [en]

    Self-bonded veneers could be an environmentally friendly alternative to the use of synthetic adhesives in the making of laminated boards. This paper describes the influence of an oxidative treatment of beech veneers using hydrogen peroxide and an iron catalyst on the properties of 2-ply laminated veneer boards formed by hot-pressing at 230-250°C. The mass loss for boards from oxidative treated veneers increased with increasing press temperature and mass loss was higher for boards made with oxidative treatment than without this treatment. Boards from oxidative treated veneer pressed at 230°C had higher shear strength than from untreated ones both before and after wet cycling. Swelling in water decreased with increasing press temperature and the results indicate that swelling of the boards in water was less when oxidatively activated veneers were used instead of untreated veneers.

  • 24.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Cristescu, Carmen
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Autoadhesion of laminated boards from Scots pine veneers: effect of oxidative pretreatment2015Ingår i: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 11, nr 4, s. 110-115Artikel i tidskrift (Refereegranskat)
    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.

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  • 25.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Dagbro, Ola
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Granlund, Kurt
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Soluble degradation products in thermally modified wood2014Ingår i: 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, s. 16-17Konferensbidrag (Refereegranskat)
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  • 26.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik. Wood Chemistry Laboratory, Department of Chemical Utilization, Forestry and Forest Products Research Institute, P.O. Box 16, Tsukuba Norin Kenkyu-Danchi Nai, Ibaraki, 305-8687, Japan.
    Ikeda, Tsutomu
    Wood Chemistry Laboratory, Department of Chemical Utilization, Forestry and Forest Products Research Institute, P.O. Box 16, Tsukuba Norin Kenkyu-Danchi Nai, Ibaraki, 305-8687, Japan.
    Kishimoto, Takao
    Laboratory of Wood Chemistry, Research Group of Bioorganic Chemistry, Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo, 060-8598, Japan; Wood Chemistry Laboratory, Department of Chemical Utilization, Forestry and Forest Products Research Institute, P.O. Box 16, Tsukuba Norin Kenkyu-Danchi Nai, Ibaraki, 305-8687, Japan.
    Magara, Kengo
    Wood Chemistry Laboratory, Department of Chemical Utilization, Forestry and Forest Products Research Institute, P.O. Box 16, Tsukuba Norin Kenkyu-Danchi Nai, Ibaraki, 305-8687, Japan.
    Matsumoto, Yuji
    Laboratory of Wood Chemistry, Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, 113-8657, Japan.
    Hosoya, Shuji
    Wood Chemistry Laboratory, Department of Chemical Utilization, Forestry and Forest Products Research Institute, P.O. Box 16, Tsukuba Norin Kenkyu-Danchi Nai, Ibaraki, 305-8687, Japan; Institute of Agricultural and Forest Engineering, University of Tsukuba, Ibaraki, 305-8572, Japan.
    Isolation of lignin-carbohydrate bonds in wood: model experiments and preliminary application to pine wood2004Ingår i: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 50, nr 2, s. 141-150Artikel i tidskrift (Refereegranskat)
    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.

  • 27.
    Karlsson, Olov
    et al.
    Wood Chemistry Laboratory, Wood Chemistry Division, Forestry and Forest Products Research Institute, Tsukuba Norin Kenkyu Danchi-Nai, Ibaraki, Japan.
    Ikeda, Tsutomu
    Wood Chemistry Laboratory, Wood Chemistry Division, Forestry and Forest Products Research Institute, Tsukuba Norin Kenkyu Danchi-Nai, Ibaraki, Japan.
    Kishimoto, Takao
    Wood Chemistry Laboratory, Wood Chemistry Division, Forestry and Forest Products Research Institute, Tsukuba Norin Kenkyu Danchi-Nai, Ibaraki, Japan.
    Magara, Kengo
    Wood Chemistry Laboratory, Wood Chemistry Division, Forestry and Forest Products Research Institute, Tsukuba Norin Kenkyu Danchi-Nai, Ibaraki, Japan.
    Matsumoto, Yuji
    Laboratory of Wood Chemistry, Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, Japan.
    Hosoya, Shuji
    Wood Chemistry Laboratory, Wood Chemistry Division, Forestry and Forest Products Research Institute, Tsukuba Norin Kenkyu Danchi-Nai, Ibaraki, Japan;Institute of Agricultural and Forest Engineering, The University of Tsukuba, 1-1-1 Tennoudai, Ibaraki, Japan.
    Ozonation of a lignin-carbohydrate complex model compound of the benzyl ether type2000Ingår i: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 46, nr 3, s. 263-265Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Evidence for the presence of lignin-carbohydrate bonds of the benzylic ether type in wood and pulps may be obtained by use of ozonation treatment to selectively degrade the lignin. It was found that the benzyl ether bond in 3-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxy-phenoxy)-3-(methyl--d-glucopyranosid-6-O-yl)-1-propanol was rather stable during ozonation in acetic acid-water-methanol 1631 at 0°C. The corresponding acid, 3,4-dihydroxy-2-(methyl--d-glucopyranosid-6-O-yl)-butanoic acid, was found to be the major reaction product. The use of ozonation followed by acid hydrolysis in connection with studies of lignincarbohydrate linkages is briefly discussed.

  • 28.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Ikeda, Tsutomu
    Magara, Kengo
    Hosoya, Shuji
    Novel method for isolation of a lignin-carbohydrate bond2001Ingår i: 11th ISWPC: Symposium on Wood and Pulping Chemistry; Nice, France, June 11 to 14, 2001, Nice, 2001Konferensbidrag (Refereegranskat)
  • 29.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Jones, Dennis
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik. Department of Forestry and Biomaterials, Czech University of Life Sciences Prague, Prague, Czech Republic.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik. Department of Forestry and Biomaterials, Czech University of Life Sciences Prague, Prague, Czech Republic.
    Phenol-formaldehyde-resin treatment of Scots pine sapwood for the reduction of resin exudation through coatings2022Ingår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 17, nr 2, s. 144-146Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Brown discolouration caused by resin exudation from knots is a problem for a range of light-coloured painted pines, and will negatively affect the appearance of the finish. To solve this problem, a hot-and-cold bath impregnation process of wood prior to painting was tested. Sawn timber, 18 × 120 mm in cross-section dimension, were heated in an oven and then immediately immersed in a cold liquid containing a phenol-formaldehyde-based solution, filling a 1–5 mm thick layer beneath the surface with phenol-formaldehyde. After curing, the timbers were painted with a white coloured coating system intended for exterior use, and tested in artificial weathering test (QUV). The phenol-formaldehyde treatment greatly reduced the discolouration of the coating compared to non-impregnated wood.

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  • 30.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Lin, Chia-Feng
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    The analysis of long-time-exposed tars from wood shingles from church roofs and facades in mid-Sweden2024Ingår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 19, nr 3, s. 783-789Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Poor condition of roofs in terms of decay of shingles and loss of tar-based surface treatments has been revealed in a number of churches at various geographical locations in mid-Sweden. The condition of tars obtained from shingles of selected churches in mid-Sweden were analysed and obtained data were compared with geographical locations of the churches. According to gas chromatography-mass spectroscopy result, dehydroabietic acid was the dominant compound found in the exposed tars from the churches except in church of Malung where similar amounts of retene was found. Oxidised resin acids were found in exposed tars from the churches but not in commercially available pit burned tar. Tar from church shingles had higher char residues than the pit burned tar which was totally consumed when heated under nitrogen gas up to 750°C using thermogravimetric analysis. Scanning electron microscopy with energy dispersive X-ray spectrometer analysis revealed higher amounts of silicates in some exposed tars; however, these compounds constituted only a minor portion of the organic matter in these specimens. Based on the data obtained in the study other factors rather than simply geographical location of churches seemed to be of importance to explain differences of the investigated properties of the church tars.

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  • 31.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Lin, Chia-Feng
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Jones, Dennis
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik. Department of Forestry and Biomaterials, Czech University of Life Sciences Prague, Prague, Czech Republic.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik. Department of Forestry and Biomaterials, Czech University of Life Sciences Prague, Prague, Czech Republic.
    Phosphorylation of Kraft lignin to be used as a water-stable fire retardant in wood2022Ingår i: Proceedings of the 10th European Conference on Wood Modification / [ed] Candelier, K., Collet, K., Dumarçay, S. et al., Nancy: University of Lorraine, Faculty of Science and Technology, Laboratory of Study and Research on the Wood Material (LERMaB) , 2022, s. 374-377Konferensbidrag (Refereegranskat)
    Abstract [en]

    Conditions for phosphorylation of softwood kraft lignin was studied. Heating lignin at 150°C with ammonium dihydrogen phosphate water solution in the presence of urea gave a phosphor content in the worked-up product of ca. 2%. The intumescent behaviour during heating could also add to the fire stability of a potential product. In order to use lignin that has been treated with phosphoric acid as fire retardant in wood, acid removal or neutralisation is needed to obtain a final sustainable product. Water washing of phosphoric acid treated lignin led, however, to significant mass losses and a material that under suitable phosphorylation conditions (low temperature and shorter periods) could be efficiently solubilised in alkaline water.

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  • 32.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Lundquist, Knut
    Acid reactions of hydrobenzoins: effect of catalyst and reaction medium on product composition1992Ingår i: Acta Chemica Scandinavica, ISSN 0904-213X, E-ISSN 1902-3103, Vol. 46, s. 283-289Artikel i tidskrift (Refereegranskat)
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    FULLTEXT01
  • 33.
    Karlsson, Olov
    et al.
    Department of Organic Chemistry, Chalmers University of Technology, Sweden.
    Lundquist, Knut
    Department of Organic Chemistry, Chalmers University of Technology, Sweden.
    Stomberg, Rolf
    Department of Inorganic Chemistry, University of Göteborg, Sweden.
    Preparation and crystal structure of (+/-)-1,2-Bis(3,4-dimethoxyphenyl)-1,2-ethanediol1993Ingår i: Acta Chemica Scandinavica, ISSN 0904-213X, E-ISSN 1902-3103, Vol. 47, s. 728-733Artikel i tidskrift (Refereegranskat)
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  • 34.
    Karlsson, Olov
    et al.
    Department of Organic Chemistry, Chalmers University of Technology, S-41296 Gothenburg, Sweden.
    Lundquist, Knut
    Department of Organic Chemistry, Chalmers University of Technology, S-41296 Gothenburg, Sweden.
    Stomberg, Rolf
    Department of Inorganic Chemistry, University of Göteborg, S-412 96, Sweden.
    Studies on hydrobenzoins: Preparation, crystal structure and stability of borate complexes1990Ingår i: Acta Chemica Scandinavica, ISSN 0904-213X, E-ISSN 1902-3103, Vol. 44, s. 617-624Artikel i tidskrift (Refereegranskat)
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  • 35.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Morén, Tom
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Colour stabilization of heat modified Norway spruce exposed to out-door conditions2010Ingår i: 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, s. 265-268Konferensbidrag (Refereegranskat)
    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.

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  • 36.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Myronycheva, Olena
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Jones, Dennis
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Elustondo, Diego
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Thermally modified wood treated with methacrylate2018Ingår i: Proceedings IRG Annual Meeting IRG49 Scientific Conference on Wood Protection Sandton, Johannesburg, South Africa 29 April-3 May, 2018Konferensbidrag (Refereegranskat)
    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.

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  • 37.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Myronycheva, Olena
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sehlstedt-Persson, Margot
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Öhman, Micael
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Multivariate modeling of mould growth in relation to extractives in dried Scots pine sapwood2017Ingår i: Proceedings IRG Annual Meetin, 2017, artikel-id 17-20629Konferensbidrag (Refereegranskat)
    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.

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    IRG/WP 17-20629
  • 38.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Pettersson, B.
    Westermark, Ulla
    Linkages between residual lignin and carbohydrates in bisulphite (magnefite) pulps2001Ingår i: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 27, nr 9, s. 310-316Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The presence of bonds between residual lignin and carbohydrates in bisulphite pulps from hardwoods and softwoods was studied. Results showed that a fraction of the residual lignin was bonded to cellulose in bisulphite pulps of softwood. The treatment with xylanase indicated the existence of alkali-stable lignin-xylan bonds in softwood bisulphite pulps.

  • 39.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Pettersson, B.
    Westermark, Ulla
    The use of cellulases and hemicellulases to study lignin-cellulose as well as lignin-hemicellulose bonds in kraft pulps2001Ingår i: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 27, nr 6, s. 196-201Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The combination of carbohydrate-degrading enzymes and size-exclusion chromatography (SEC) has been used to analyze the existence of covalent bonds between lignin and cellulose and/or hemicelluloses in pulps. Cellulases and xylanase were used for degradation of cellulose and xylan, respectively. Analysis of the molecular weight profiles of lignin and carbohydrates before and after enzymic hydrolysis were performed by dissolution of the pulps in LiCl/dimethylacetamide (DMAC). The results indicate that a considerable part of the residual lignin in unbleached pine kraft pulp is bond to cellulose. Bonding of lignin to xylan in the pine kraft pulp could also be detected. Analysis of birch kraft pulp shows that most of the residu lignin in birch kraft pulps is covalently linked to xylan. The combination of carbohydrate-degrading enzymes and SEC in LiCl/DMAC seems to be an excellent way of characterizing bonds between lignin and carbohydrates in chemical pulps.

  • 40.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sidorova, Ekaterina
    SP Technical Research Institute of Sweden, S-114 86 Stockholm, Drottning Kristinas väg 67, Sweden.
    Morén, Tom
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Influence of heat transferring media on durability of thermally modified wood2011Ingår i: BioResources, E-ISSN 1930-2126, Vol. 6, nr 1, s. 356-372Artikel i tidskrift (Refereegranskat)
    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).

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  • 41.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Torniainen, Petteri
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Dagbro, Ola
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Granlund, Kurt
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Morén, Tom
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Presence of water-soluble compounds in thermally modified wood: Carbohydrates and furfurals2012Ingår i: BioResources, E-ISSN 1930-2126, Vol. 7, nr 3, s. 3679-3689Artikel i tidskrift (Refereegranskat)
    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.

  • 42.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Westermark, Ulla
    Auto-adhesive bonding by oxidative treatment of wood2003Ingår i: 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, s. 365-368Konferensbidrag (Refereegranskat)
  • 43.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Westermark, Ulla
    Evidence for chemical bonds between lignin and cellulose in kraft pulps1996Ingår i: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 22, nr 10, s. J397-401Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The cellulose solvent system LiCl-dimethylacetamide has been used to dissolve kraft pulps prepared from pine and birch. The dissolved polymers were analyzed using size-exclusion chromatography combined with both RI- and UV-detection systems in order to monitor simultaneously the major wood polymers (cellulose, hemicellulose and lignin). Kraft pulps from birch were completely soluble in the solvent system and the pine kraft pulp about 80% soluble. Analyses of the kraft pulps strongly suggest that a considerable amount of the residual lignin is chemically linked to the high molecular weight cellulose in pine but not in birch. The presence of stable lignin-cellulose bonds will reduce the possibility of achieving a low kappa number by cooking. For comparison, sulphite and bisulphite pulps were also examined. Both pulps were soluble in the solvent system and analyses indicated that lignin-cellulose bonds also exist in these pulps although to a significantly lesser extent than in the pine kraft pulp

  • 44.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Westermark, Ulla
    Resin-free particleboard by oxidation of wood2002Ingår i: 6th Pacific Rim Bio-Based Composites Symposium & Workshop on the Chemical Modification of Cellulosics: November 10th to 13th 2002, Portland, Oregon ; proceedings / [ed] P. E. Humphrey, Corvallis, Or: Wood science and engineering department , 2002Konferensbidrag (Refereegranskat)
  • 45.
    Karlsson, Olov
    et al.
    Swedish Pulp and Paper Institute (STFI), Stockholm, Sweden.
    Westermark, Ulla
    Swedish Pulp and Paper Institute (STFI), Stockholm, Sweden.
    The significance of glucomannan for the condensation of cellulose and lignin under kraft pulping conditions1997Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 12, nr 2, s. 90-93Artikel i tidskrift (Refereegranskat)
  • 46.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Westermark, Ulla
    Backlund, Ulrika
    Metso, Sundsvall.
    Halvarsson, Sören
    Mittuniversitetet.
    Environmentally friendly process for high density fibreboards2006Konferensbidrag (Övrigt vetenskapligt)
    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.

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  • 47.
    Karlsson, Olov
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Yang, Qian
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sehlstedt-Persson, Margot
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Morén, Tom
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Heat treatments of high temperature dried norway spruce boards: Saccharides and furfurals in sapwood surfaces2012Ingår i: BioResources, E-ISSN 1930-2126, Vol. 7, nr 2, s. 2284-2299Artikel i tidskrift (Refereegranskat)
    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.

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  • 48.
    Kim, Injeong
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Jones, Dennis
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Antzutkin, Oleg N.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Shah, Faiz Ullah
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Investigations into the use of Maleic Anhydride/Sodium Hypophosphite as a Wood Modification Process2020Ingår i: Proceedings IRG Annual Meeting 2020, Stockholm: The International Research Group on Wood Protection , 2020, artikel-id IRG/WP 20-40891Konferensbidrag (Refereegranskat)
    Abstract [en]

    The formation of crosslinked bonds between wood constituents is believed to be an effective way to stabilize wood against wet conditions. The possibility to use maleic anhydride (MA) combined with sodium hypophosphite (SHP) as crosslinking agents was studied, using Scots pine sapwood and a model compound. The modified wood showed weight gain and bulking effect after treatment and subsequent Soxhlet extractions, which indicated penetration into the wood cell wall and reaction of the chemicals with the wood constituents. The FTIR spectra confirmed the formation of an ester bond between the wood and MA. Furthermore, a decrease of intensity of band at 1635 cm-1 indicated a reduction of the double bond between carbons in MA after further treatment with SHP, especially at 170 ̊C. Such reactions were studied using monomethyl maleate (MMM) and SHP. The 13C NMR spectra of the reaction product confirmed a reduction of the double bond between carbons. This paper outlines studies undertaken to date, along with outlining aims of ongoing and future work.

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    fulltext
  • 49.
    Kim, Injeong
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Antzutkin, Oleg
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Shah, Faiz Ullah
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Jones, Dennis
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Wood modification with maleic anhydride and sodium hypophosphite2019Ingår i: Proceedings of the 20th International Symposium on Wood, Fiber and Pulping Chemistry, ISWFPC20, September 9-11, 2019, Tokyo, Japan, 4 pp., Tokyo: The University of Tokyo , 2019, s. 1-4Konferensbidrag (Refereegranskat)
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    fulltext
  • 50.
    Kim, Injeong
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Jones, Dennis
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik. Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, Suchdol, 165 21, Praha 6, Czech Republic.
    Mantanis, George
    Department of Forestry, Wood Sciences and Design, Laboratory of Wood Science and Technology, University of Thessaly, 43100, Karditsa, Greece.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik. Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, Suchdol, 165 21, Praha 6, Czech Republic.
    Dimensional stabilisation of Scots pine (Pinus sylvestris L.) sapwood by reaction with maleic anhydride and sodium hypophosphite2021Ingår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 79, nr 3, s. 589-596Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wood has the ability to absorb and desorb moisture, which can affect its dimensional size when in use. Limiting this can provide products with greater shape stability and less stresses on external coatings. One method that has been investigated for achieving this has been through chemical modification. In this work, the dimensional stabilisation imparted to Scots pine sapwood by chemical modification with maleic anhydride (MA) combined with sodium hypophosphite (SHP) was investigated. The influence of concentration of MA, treatment temperature and treatment period on weight percent gain (WPG) and bulking coefficient (BC) during treatment with MA and SHP of wood was studied. Furthermore, dimensional stability was determined by the water soak/oven dry method (wet-dry cycle) through five cycles in order to determine the hydrolytic stability of the ester bond and any potential cross-linking reactions. Wood blocks (20 × 20 × 10 mm) modified with MA combined with SHP exhibited lower weight loss following water soaking than unmodified blocks or MA-treated blocks. Wood blocks modified with MA and SHP showed the best anti-swelling efficiency and minimum wet-volume (water-saturated). However, as the concentration of SHP increased, dimensional stability was diminished without any increase in weight percentage gain after water soaking. When combined with FTIR results, it appeared that the modification with MA and SHP seemed to form cross-linking between wood constituents, though high concentration of SHP did not seem to result in additional cross-linking.

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