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  • 1.
    Ahmed, Sheikh Ali
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hansson, Lars
    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.
    Distribution of preservatives in thermally modified Scots pine and Norway spruce sapwood2013In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 47, no 3, p. 499-513Article in journal (Refereed)
    Abstract [en]

    Studying the impregnation and distribution of oil-based preservative in dried wood is complicated as wood is a nonhomogeneous, hygroscopic and porous material, and especially of anisotropic nature. However, this study is important since it has influence on the durability of wood. To enhance the durability of thermally modified wood, a new method for preservative impregnation is introduced, avoiding the need for external pressure or vacuum. This article presents a study on preservative distribution in thermally treated Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) sapwood using computed tomography scanning, light microscopy, and scanning electron microscopy. Secondary treatment of thermally modified wood was performed on a laboratory scale by impregnation with two types of preservatives, viz. Elit Träskydd (Beckers) and pine tar (tar), to evaluate their distribution in the wood cells. Preservative solutions were impregnated in the wood using a simple and effective method. Samples were preheated to 170°C in a drying oven and immediately submerged in preservative solutions for simultaneous impregnation and cooling. Tar penetration was found higher than Beckers, and their distribution decreased with increasing sample length. Owing to some anatomical properties, uptake of preservatives was low in spruce. Besides, dry-induced interstitial spaces, which are proven important flow paths for seasoned wood, were not observed in this species.

  • 2.
    Ahmed, Sheikh Ali
    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.
    Moisture properties of heat-treated Scots pine and Norway spruce sapwood impregnated with wood preservatives2012In: Wood and Fiber Science, ISSN 0735-6161, Vol. 44, no 1, p. 85-93Article in journal (Refereed)
    Abstract [en]

    An experiment was conducted on commercially heat-treated (HT) Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies [L.] Karst.) sapwood collected from Ht Wood AB, Arvidsjaur, Sweden. Secondary treatment on HT wood was performed in laboratory scale by impregnating with water-repellent preservatives (a commercial one and pine tar) to evaluate their retention and different moisture-related properties. Preservative solutions were impregnated using a simple and effective method. Wood samples were heated at 170°C in a dry oven and were immediately immersed in preservative solutions. Considerable retention was observed in HT wood, particularly in pine. Moisture adsorption properties were measured after conditioning in a high-humidity environmental chamber (4°C and 84% RH). Experimental results showed that secondary treatment enhanced moisture excluding efficiencies by decreasing equilibrium moisture content, suggesting better hydrophobicity. Soaking test in water showed that antiswelling and water repellence efficiencies improved, especially in tar-treated wood. In addition, this type of treatment significantly decreased water absorption. It was also possible to decrease volumetric swellings. Thus, secondary treatment of HT wood with preservative, in particular with tar, improved dimensional stability and water repellency.

  • 3.
    Ahmed, Sheikh Ali
    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.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Cloutier, Alain
    Wood Research Center (CRB), Department of Wood and Forest Sciences, Faculty of Forestry, Geography and Geomatics, Laval University, Quebec.
    Fang, Chang-Hua
    Wood Research Center (CRB), Department of Wood and Forest Sciences, Faculty of Forestry, Geography and Geomatics, Laval University, Quebec.
    Elustondo, Diego
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Anatomical properties and process parameters affecting blister/blow formation in densified European aspen and downy birch sapwood boards by thermo-hygro-mechanical compression2013In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 48, no 24, p. 8571-8579Article in journal (Refereed)
    Abstract [en]

    Approximately, 13.5 % of the standing volume of productive forest land in Sweden is covered by birch and aspen, which provides the vast potential to produce value-added products such as densified wood. This study shows whether it is possible to densify those species with a thermo-hygro-mechanical (THM) process using heat, steam, and pressure. In this process, transverse compression on thin European aspen (Populus tremula) and downy birch (Betula pubescens) boards was performed at 200 ºC with a maximum steam pressure of 550 kPa. To obtain a theoretical 50 % compression set, the press’s maximum hydraulic pressure ranged from 1.5 to 7.3 MPa. Preliminary tests showed that ~75 % of the birch boards produced defects (blisters/blows) while only 25 % of the aspen boards did. Mainly, radial delamination associated with internal checks in intrawall and transwall fractures caused small cracks (termed blisters) while blows are characterized by relatively larger areas of delamination visible as a bumpy surface on the panel. Anatomical investigations revealed that birch was more prone to those defects than aspen. However, those defects could be minimized by increasing the pre-treatment time during the THM processing.

  • 4.
    Ahmed, Sheikh Ali
    et al.
    Department of Forestry and Wood Technology, Faculty of Technology, Linnaeus University.
    Morén, Tom
    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.
    Blom, Åsa
    Department of Forestry and Wood Technology, Faculty of Technology, Linnaeus University.
    Effect of oil impregnation on water repellency, dimensional stability and mold susceptibility of thermally-modified European aspen and downy birch wood2017In: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 63, no 1, p. 74-82Article in journal (Refereed)
    Abstract [en]

    Conventional chemical wood preservatives have been banned or restricted in some applications due to human and animal toxicity and their adverse impact on the surrounding environment. New, low-environmental-impact wood treatments that still provide effective protection systems are needed to protect wood. Thermal modification of wood could reduce hygroscopicity, improve dimensional stability and enhance resistance to mold attack. The aim of this study is to investigate if these properties enhanced in thermally-modified (TM) wood through treatments with oils. In this study, TM European aspen (Populus tremula) and downy birch (Betula pubescens) wood were impregnated with three different types of oil: water-miscible commercial Elit Träskydd (Beckers oil with propiconazole and 3-iodo-2-propynyl butylcarbamate, IPBC), a pine tar formulation and 100% tung oil. The properties of oil-impregnated wood investigated were water repellency, dimensional stability and mold susceptibility. The treated wood especially with pine tar and tung oil, showed an increase in water repellency and dimensional stability. However, Beckers oil which contains biocides like propiconazole and IPBC, showed better protection against mold compared with pine tar and tung oil. To enhance the dimensional stability of the wood, pine tar and tung oil can be used, but these oil treatments did not significantly improve mold resistance rather sometimes enhanced the mold growth. Whereas, a significant anti-mold effect was observed on Beckers oil treated samples.

  • 5.
    Ahmed, Sheikh Ali
    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.
    Hansson, Lars
    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.
    Evaluation of preservative distribution in thermally modified European aspen and birch boards using computed tomography and scanning electron microscopy2013In: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 59, no 1, p. 57-66Article in journal (Refereed)
    Abstract [en]

    The aim of this experiment was to impregnate thermally modified wood using an easy and cost-effective method. Industrially processed thermally modified European aspen (Populus tremula L.) and birch (Betula pubescens Ehrh.) were collected and secondarily treated at the laboratory scale with the preservatives tung oil, pine tar and Elit Träskydd (Beckers) using a simple and effective method. Preservative uptake and distribution in sample boards were evaluated using computed tomography (CT) and scanning electron microscopy (SEM) techniques. Preservative uptake and treatability in terms of void volume filled were found the highest in Beckers and the lowest in tung oil-treated samples. Thermally modified samples had lower treatability than their counterpart control samples. More structural changes after thermal modification, especially in birch, significantly reduced the preservative uptake and distribution. The differences of preservatives uptake near the end grain were high and then decreased near the mid position of the samples length as compared with similar type of wood sample. Non-destructive evaluation by CT scanning provided a very useful method to locate the preservative gradients throughout the sample length. SEM analysis enabled the visualization of the preservative deposits in wood cells at the microstructural level.

  • 6. 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.

  • 7.
    Ahmed, Sheikh Ali
    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.
    Development of a new rapid method for mould testing in a climate chamber: Preliminary tests2013In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 71, no 4, p. 451-461Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to develop fast, simple and robust solid wood mould testing methods for the use in small-scale laboratory tests. The objective was to investigate mould susceptibility of different wood materials within the batches. The proposed method is based on natural contamination of non-sterile surfaces in climates conducive to mould growth. For this purpose, a climate chamber with regulated temperature and relative humidity was used. The conditioning chamber was divided into upper and lower chamber by a thin layer of stainless steel placed horizontally above the fan to minimise air circulation to the sample in the upper compartment. Mould-infected samples from outdoor tests were used as a source of mould inocula, and test trials were conducted on Scots pine (Pinus sylvestris L.) sapwood. Samples were suspended from the top of the upper chamber, and the chamber was exposed to different temperature and humidity levels. Severe mould infestation was observed after 12-14 days of incubation. Visual mould rating was then performed. Regardless of some constraints, this test method was very simple, fast, and effective. More importantly, unlike other test methods, it closely models mould infestation as it would occur under natural condition.

  • 8.
    Ahmed, Sheikh Ali
    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.
    Mould susceptibility of Scots pine (Pinus sylvestris L.) sapwood: Impact of drying, thermal modification, and copper-based preservative2013In: International Biodeterioration & Biodegradation, ISSN 0964-8305, E-ISSN 1879-0208, Vol. 85, p. 284-288Article in journal (Refereed)
    Abstract [en]

    The development of mould on wood surfaces depends on several factors. Although mould does not affect the mechanical properties of wood, it greatly reduces the aesthetic value of wood like the sapwood of Scots pine (Pinus sylvestris L.), which is very prone to mould. In addition, adverse health effects of mould on humans are also a great concern. Different types of dried and treated wood were used to observe whether they had enhanced durability against mould following an accelerated laboratory test method in a climate chamber. Samples were green, air-dried, industrially thermally-modified, treated with copper-based preservative, and kiln-dried wood, which were tested within a single test run. The test produced the following main results: the thermal modification increased the durability of the wood, and the protective effectiveness of alternative treatments was comparable to that of commercially available copper-based treatment. However, the initial moisture content of the samples during mould exposure had a great influence on the onset of mould growth. The risk of mould susceptibility of industrial kiln-dried lumber can be reduced by drying using the double-layering technique which likely forced the nutrients to deposit near the evaporation surfaces followed by planing off the nutrient enriched edges.

  • 9.
    Ahmed, Sheikh Ali
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Yang, Qian
    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.
    Accelerated mold test on dried pine sapwood boards: Impact of contact heat treatment2013In: Journal of wood chemistry and technology, ISSN 0277-3813, E-ISSN 1532-2319, Vol. 33, no 3, p. 174-187Article in journal (Refereed)
    Abstract [en]

    We test the hypothesis that the combination of kiln drying of double-stacked boards and contact heat treatment will reduce the susceptibility of treated boards to colonization by mold fungi. Winter-felled Scots pine (Pinus sylvestris L.) sapwood boards were double-stacked in an industrial kiln in ‘‘sapwood out’’ and ‘‘sapwood in’’ positions. Dried samples were then contact heat-treated using a hot press at three different temperatures (140°C, 170°C, and 200°C) for three different periods (1, 3, and 10 min). Accelerated mold test was performed in a climate chamber where naturally mold infected samples were used as a source of mold inocula. Contact heat treatment degraded the saccharides which accumulated at dried surfaces, and reduced the mold growth. The threshold temperature and time for inhibiting mold growth was 170°C for 10 min. But, for industrial application, the most feasible combination of temperature and time would be 200°C for 3 min. We concluded that double stacking/contact heat treatment used is an environmentally friendly alternative to chemicals for reducing mold on Scots pine sapwood boards.

  • 10.
    Couceiro, José
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Vikberg, Tommy
    SP Technical Research Institute of Sweden .
    Hansson, Lars
    Natural Sciences and Preliminary Courses, NTNU Ålesund, Norway .
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    In Situ CT-Scanning of Checking and Collapse Behaviour of Eucalyptus nitens During Drying2016In: Proceedings of the 59th International Convention of Society of Wood Science and Technology March 6-10, 2016 – Curitiba, Brazil, 2016Conference paper (Other academic)
    Abstract [en]

    Eucalyptus nitens has become a commercially important species in Chile and it isrepresenting one of the fastest growing wood-stock in the country. Today, it is widelyused for pulp and paper production, but the interest in using the solid wood has increasedin recent years. Before the sawn timber can be utilized, its moisture content must bereduced. Often during drying, hydrostatic tension forces within the cell exceed thecompressive strength of the thin cell wall of Eucalyptus nitens and the cell collapses. Thisphenomenon usually leads to severe surface deformation and both surface and internalcracks (honeycombing). Yield and quality of the final product, and thereby sawmills’profitability, are decreased by these cracks and deformations. The aim of this study wasto investigate, by CT-scanning samples throughout the drying process, if it is possible todetect when and how cracking and deformation occurs and develops in specimens ofEucalyptus nitens from Chile. Based on this knowledge, better drying schedules canhopefully be developed to improve the yield and provide a higher end-quality of the sawntimber.

  • 11.
    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

  • 12.
    Dagbro, Ola
    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.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Thermal modification of birch using saturated and superheated steam2011In: Proceedings of the 7th meeting of the Nordic-Baltic Network in Wood Material Science and Engineering (WSE): October 27-28, 2011, Oslo, Norway / [ed] Erik Larnøy; Gry Alfredsen, Ås: Norsk institutt for skog og landskap , 2011, p. 43-48Conference paper (Refereed)
    Abstract [en]

    During the thermal modification, wood is normally exposed to temperatures between 160 - 220°C. As a result physical and chemical changes are taking place and some of the wood properties are changed. Dimensional stability and weather resistance are improved. On the other hand the mechanical strength properties are usually negatively affected by the treatment. The visual appearance is also changed. There were two different types of thermal modification processes used in this study. One of them was using saturated steam and the other one superheated steam. Treatment temperature was 160°C in saturated steam process and 185°C in superheated steam. The wood specie used in this study was Silver birch (Betula pendula). In the chemistry part the acid content was investigated. Despite the 25°C lower treatment temperature, birch modified in saturated steam was more acidic compared to birch modified in superheated steam. Some differences in equilibrium moisture content (EMC) and dimensional stability were found mainly in the environment T=20°C and RH=85%. The colour of birch treated in saturated steam at 160°C was darker than the colour of birch treated in superheated steam at temperature 185°C.

  • 13. Danvind, Jonas
    et al.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Using X-ray CT scanning for moisture and displacement measurements in knots and their surroundings2004Conference paper (Refereed)
  • 14. Esping, Björn
    et al.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Program för svensk trätorkningsforskning 1983-19861983Report (Other academic)
  • 15. Esping, Björn
    et al.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Program för svensk trätorkningsforskning 1983-19861983Report (Other academic)
  • 16.
    Hansson, Lars
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Antti, Lena
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    IR- och HFV-teknik för virkestorkning2002Report (Other academic)
    Abstract [sv]

    Syftet med föreliggande arbete är att presentera några relativt nya virkestorkningsmetoder. Tanken är att visa på metodernas möjligheter och begränsningar för den svenska träbranschen. De metoder som valts ut är torkning med hjälp av infraröd strålning och högfrekvens/vakuum-torkning. Studien baseras på fysikaliska förutsättningar, litteraturinventering, intervjuer med metodutvecklare och i IR-fallet på medverkan vid praktiska kvalitetsmätningar av det torkade virket. Resultatet visar att teknologin som bygger på infraröd teknik möjligen kan minska torkningstiden, men detta antagande bygger endast på den grundläggande fysiken bakom teknologin. De som har investerat i denna teknologi vill ej ge ut information kring tekniken innan den grundligt har testats. Därför finns en del obesvarade frågeställningar, såsom hur mycket tid som kan tjänas vid torkningen, energiåtgångens storlek samt vilken torkningskvalitet som erhålls med denna torkningsmetod. Det sistnämnda undersöks för närvarande av Trätek. Högfrekvens/vakuumtekniken som beskrivs här är utvecklad i Kanada och används industriellt där, än så länge dock i liten skala. Träslag som på senare tid undersökts och torkas med denna metod är företrädesvis nordamerikanskt barrvirke. Metoden lämpar sig ur ekonomiskt perspektiv (i Kanada) framför allt för torkning av grövre dimensioner, men också för att fuktutjämna konventionellt torkat virke. Fördelarna med metoden jämfört med konventionell teknik är kortare torkningstid, mindre förekomst av ytsprickor, inre spänningar och fläckvis missfärgning förekommer inte alls och dessutom uppnås en jämn slutfuktkvot i hela lasten. Virket behöver inte ströläggas då den huvudsakliga fukttransporten sker i fiberriktningen. Svårigheter med torkstyrningen i form av övertorkning och kollaps har numera minimerats genom den senaste generationen högfrekvens-/vakuumtorkar. Metoden kräver tillgång till elenergi och energiförbrukningen uppges till 1.2 kWh per kg bortfört vatten.

  • 17.
    Hansson, Lars
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Cherepanova, Ekaterina
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    CT-scanning during heat treatment of wood2011In: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 7, no 4, p. 11-17Article in journal (Refereed)
    Abstract [en]

    Earlier experiences from industrial heat treatment of wood with the ThermoWood® process show that more or less extensive internal cracking may occur for thicker dimensions. This type of timber damage is particularly troublesome because these cracks do not reach the surface and are thus not visible on unprocessed timber. After resawing or planing the boards, cracks can appear, resulting in costly downgrading of the material. The ThermoWood® heat treatment process can be divided into six periods. The first period, the heating period, is when saturated steam is injected into the kiln, the second period is the drying step, which can be either high or low temperature drying, the third period is when the final heating and drying take place, the fourth period is when the temperature is kept constant for about 2–4 hours, the fifth period is the cooling regime, the sixth period is the conditioning regime for remoistening the material, and the last period is the cooling one. At the Division of Wood Physics at Luleå University of Technology in Skellefteå a climate chamber has recently been installed. This climate chamber together with a CTscanner makes it possible to study wood density changes in different climates. As the maximum temperature that can be reached in the climate chamber is 220 °C, it is also possible to study the heat treatment process, besides conventional air circulation drying. The aim of this study was to use the CT-scanning (CT) technique during heat treatment of wood in order to investigate whether it is possible to detect internal checking in situ during the treatment.

  • 18. Johansson, Dennis
    et al.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    The potential of colour measurement for strength prediction of thermally treated wood2006In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 64, no 2, p. 104-110Article in journal (Refereed)
    Abstract [en]

    This paper investigates the effects of thermal treatment of birch with respect to colour and strength. Birch wood was treated at 175 °C and 200 °C for 0 h, 1 h, 3 h and 10 h. In bending-strength experiments, treatment was also performed at 185 °C for 2 h. Both static bending strength and impact bending strength were investigated using multivariate statistics (PLS) for correlation to process parameters, density, EMC, position in board, modulus of elasticity (only in static bending), colour and dimensions of samples. In static bending, two PLS models were designed, one based on process parameters and the other based on colour and EMC. From these models it was concluded that colour is not a useful parameter for prediction of strength. In impacted bending, the correlation was too small to give useful results. One test of static bending strength with matched samples was performed, and it showed a strength reduction of 43% when treatment was conducted at 200 °C for 3 h. Measurement of colour homogeneity of the treated boards showed that the colour is not homogeneous.

  • 19. Johansson, Dennis
    et al.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Morén, Tom
    Effect of heat treatment on capillary water absorption of heat-treated pine, spruce and birch2006In: Wood structure and properties '06: [proceedings of the 5th IUFRO Symposium Wood Structure and Properties '06 held on September 3-6, 2006 in Sliač - Sielnica, Slovakia] / [ed] R. Lagana; S. Kurjatko; J. Kudela, Zvolen, Slovakia: Arbora Publishers , 2006, p. 251-255Conference paper (Refereed)
    Abstract [en]

    Longitudinal absorption of water in matched heat-treated and untreated boards was studied. The boards are from three different species. Scots pine (Pious sylvestris), Norway spruce (Picea abies) and birch (Betula pubescens). The heat treatment was performed according to the Thermowood process at two different temperature levels (170 degrees C and 200 degrees C) for all three species. Computer tomography (CT) scanning was used to intermittently monitor the ascent of the water front. The use of CT scanning enables a study of the liquid water ascent in three dimensions over time. This means that it is possible to determine the influence of different treatment temperatures and species as well as the difference between heartwood and sapwood on capillary action.The results show that longitudinal water absorption in pine sapwood was substantially lamer when heat-treated at 170 degrees C compared to untreated pine sapwood. In pine heartwood, the ascent of water was low in heat-treated as well as in untreated boards. Spruce boards showed low water absorption in sap- and heartwood in heat-treated as well as in untreated boards. Birch showed a decreasing uptake of water with increasing treatment temperature

  • 20.
    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.

  • 21.
    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.

  • 22.
    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).

  • 23.
    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.

  • 24. Larsson, R.
    et al.
    Danvind, Jonas
    Imbaud, O.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Prediction modelling of colour changes on boards of Norway Spruce and Scots Pine during low temperature drying2005In: Proceedings: 9th International IUFRO Wood Drying Conference, Nanjing Forestry University , 2005Conference paper (Refereed)
  • 25.
    Larsson, R.
    et al.
    Valutec AB, Skellefteå.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Implementation of adaptive control systems in industrial dry kilns2003In: Proceedings 8th International IUFRO Wood Drying Conference: Improvement and innovation in wood drying : a major issue for a renewable material : 24-29 August 2003, Brasov, Romania / [ed] Mihai Ispas; Sergiu T Chiriacescu, Brasov: Transilvania University of Brasov, Faculty of Wood Industry , 2003, p. 397-400Conference paper (Refereed)
    Abstract [en]

    Capacity optimisation of Norway spruce, 150x50 mm2 was carried out in a full-scale kiln dryer starting at 50 °C wet bulb temperature. The objective was to reach as high capacity as possible. Maximum allowed moisture content (MC) standard deviation was 10% of the end moisture content value with 2 % maximum allowed amount of checks. An adaptive control strategy for the process control of a kiln dryer was used to optimise the drying process. The temperature drop across the load (TDL) was used to achieve a constant moisture flux from the drying batch. The drying time was 56 h and the total cycle time was 66. 7 h. The end moisture content was 15. 6 % with a standard deviation of 1. 4 %-units. It was concluded that adjustments in TDL due to the amount of heartwood need to be done using this control strategy. Optimising start parameters for different wood species and board dimensions considering maximum allowed checking is important to achieve maximum capacity with this control strategy.

  • 26. Larsson, Robert
    et al.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Danvind, Jonas
    Styrsystem för ändamålsstyrd torkning: förutsättningar och industriförsök2002Report (Other academic)
    Abstract [sv]

    Del A: Inledningsvis behandlas allmänna principer för adaptiv reglering av torkprocessen vad gäller solitt trä. De grundläggande meknaismerna som ligger bakom fukttransporten i trä vid artificiell torkning beskrivs även. På basis av denna fundamentala kunskap kan exempelvis parameterstyrning utvecklas för industriella satstorksystem. Ett antal principer för sådan styrning har implementerats i en laboratorietork. Del B: Ett antal industriförsök i full skala har genomförts för att undersöka hur en dynamisk återkoppling i styrsystemet kan ske. Exempelvis finns tydliga samband mellan vireksstapelns krympning och dess medelfuktkvot, vilket tillsammans med andra signaler från torkningen kan ge återkoppling i styrsystemet. En multivariat ansats kan vara en möjlig utveckling till ett styrsystem som även innefattar ett integrerat expertsystem för färgstyrning bl a.

  • 27.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Check formation during low temperature dryin on Scots pine: theoretical considerations experimental results1989In: Upgrading wood quality through drying technology: proceedings of the IUFRO International Wood Drying Symposium, July 23-28, 1989, Seattle, Washington, USA / [ed] Ferhan Kayihan; Jay A. Johnson; Ramsay Smith, Tacoma, Wash: IUFRO , 1989Conference paper (Refereed)
  • 28.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Conditioning of Pine during artificial drying in a kiln1987In: Proceedings of the International Conference on Stress Development and Degrade During Wood Drying, Skellefteå, Sweden, September 28-October 2, 1987 / [ed] Tom Morén; O. Söderström, Skellefteå: Luleå University of Technology, Dept. of Wood Technology , 1987Conference paper (Refereed)
  • 29.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Creep, deformation and moisture redistribution during air convective wood drying and conditioning: air convective wood drying and conditioning1993Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Air convective wood drying is associated with a considerable risk for damage to the timber, especially checking and warping. This thesis contains an analysis of creep and deformation during wood drying related to stress development and susceptibility of checking. Also heat and mass transfer problems in the wood drying process are considered. Finally an investigation of different conditioning treatments as a way of relaxing residual stress and moisture gradients is presented. Related to the studies mentioned above, this thesis describes some useful techniques to evaluate deformation, moisture flux and redistribution by nondestructive and non-contact measurements. Moisture flux is evaluated by infrared thermography, surface moisture content by near-infrared measurements, displacement by white light speckle photogrametry and moisture pickup during steaming by computer tomography. The results show that during air convective drying the heat transfer from hot humid air to the wood starts a surface evaporation which differs between sapwood and heartwood but also between earlywood and latewood in the annual ring. This evaporation pattern is caused by the amount of water contained in these tissues of the wood and also by the pit aspiration, especially in the earlywood cells. Another result shows that Fickian diffusion theory for wood results in a mass transfer coefficient (surface emission factor) which is not in accordance with classical heat and mass transfer boundary layer theory. The mass transfer coefficient is one order of a magnitude lower than the ones obtained from classical theory. Checking susceptibility is closely related to stress development across the grain during drying. The tension stress at the beginning of the drying period develops rapidly causing a creep response of the surface. This mechanosorptive creep relaxes the tension stress enough to prevent checking in many cases. This effect is more pronounced at elevated temperatures. It is shown that high density and low temperature make wood more susceptible to checking, a property closely related to the value of strain at failure. Warping during drying is generally caused by the anisotropic shrinkage of wood. The study of cupping shows that it depends mainly on the differential shrinkage in tangential and radial direction but also that cupping is reduced to some extent by the creep of the surface layer. However during the conditioning treatment cupping increases to values near those reached after stress free drying. Finally conditioning tests in saturated water steam show that this treatment is an efficient way of relaxing residual drying stress as well as to equalize moisture variation. Also steaming offers an interesting method of fast and efficient heating prior to the drying period.

  • 30.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    CT-scanning of wood during drying: Consequences for the development of adaptive kiln-control systems2000Conference paper (Refereed)
  • 31.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Heating and conditioning by steaming during low-temperature drying1994In: Improving wood drying technology August 9 - 13th, 1994, Rotorua, New Zealand: August 9 - 13th, 1994, Rotorua, New Zealand : 4th IUFRO International Conference on Wood Drying / [ed] A.N Haslett, New Zealand Forest Research Institute , 1994Conference paper (Refereed)
  • 32.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Infrared thermography in the analysis of moisture flux from drying wooden surfaces1992In: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 10, no 5, p. 1219-1230Article in journal (Refereed)
  • 33.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Steam conditioning after low temperature drying1994In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 52, no 2, p. 77-82Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to investigate the response of saturated water vapour steaming on boards from Scots pine and Norway spruce. Steaming treatment of the predried boards were done in a laboratory chamber equipped with a 1.5 kW electric water boiler. The experiments were performed mainly at 100°C in saturated steam and the relation between temperature and moisture pickup as well as stress relaxation was studied. The results showed that steaming is a very efficient process to relax stress and equalise moisture gradients in boards. The gain of time is considerable; steaming takes only about 10% of traditional conditioning time at lower temperatures. The temperature rise is correlated to moisture pickup from surface condensation resulting in the possibility of estimating the increase of moisture content during steaming from measurements of temperature.

  • 34.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Temperaturfall i cirkulationsluften vid kammartorkning1984Report (Other academic)
  • 35.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    The effect of drying and conditioning on the cupping of boards from Pinus sylvestris and Picea abies1993In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 51, no 4, p. 296-Article in journal (Refereed)
  • 36.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Torkning av furu i det hygroskopiska området1987Report (Other academic)
  • 37.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Vidaretorkning och konditionering av furuvirke1987Report (Other academic)
  • 38.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Vidaretorkning och konditionering av furuvirke1987Report (Other academic)
  • 39.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Larsson, Robert (Publisher)
    Virkestorkningens grunder: en bok för personer verksamma inom träindustrin samt för områdets utbildningar2007Book (Other (popular science, discussion, etc.))
  • 40.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Värmelära: exempelsamling med lösta exempel1979Report (Other academic)
  • 41.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Värmelära: problemsamling med lösta exempel1978Report (Other academic)
  • 42.
    Morén, Tom
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Salin, Jarl-Gunnar
    Söderström, Ove
    Determination of the surface emission factors in wood sorption experiments: paper presented at 3rd IUFRO International Wood Drying Conference, Vienna, August 18-21, 19921993Report (Other academic)
  • 43.
    Morén, Tom
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Salin, J.G.
    Söderström, O.
    Determination of the surface emission factors in wood sorption1992In: Understanding the wood drying process: a synthesis of theory and practice ; [proceedings of the] 3rd IUFRO conference on wood drying, August 18-21, 1992, Vienna, Austria, Wien: IUFRO , 1992Conference paper (Refereed)
  • 44.
    Morén, Tom
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Analys av olika metoder för utformning av hörnskarv av tätningslist1983Report (Other academic)
  • 45.
    Morén, Tom
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Creep formation of the surface layer of timber boards during air circulation drying1992In: Understanding the wood drying process: a synthesis of theory and practice ; [proceedings of the] 3rd IUFRO conference on wood drying, August 18-21, 1992, Vienna, Austria, Wien: IUFRO , 1992Conference paper (Refereed)
  • 46.
    Morén, Tom
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Cupping of center boards during drying due to anisotropic shrinkage1992In: Understanding the wood drying process: a synthesis of theory and practice : [proceedings of the] 3rd IUFRO conference on wood drying, August 18-21, 1992, Vienna, Austria, Wien: IUFRO , 1992Conference paper (Refereed)
  • 47.
    Morén, Tom
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Desorptionsisoterm för furu och gran vid 20° och 50° C1984Report (Other academic)
  • 48.
    Morén, Tom
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Draghållfasthet och E-modul: nordsvensk furu och gran i området för artificiell torkning1984Report (Other academic)
  • 49.
    Morén, Tom
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Formförändringar hos virke: Torkning av granreglar från klentimmer2001Report (Other academic)
    Abstract [sv]

    Två delstudier har gjorts med syfte att studera träreglars formbeständighet vid industriell produktion av granreglar sågat från klentimmer. Delstudie I omfattar studier av virkesegenskapers, och då främst fibervinkelns inverkan på virkesdeformation men även processparametrar som virkeslängd, paketläggning samt belastning under torkning ingår. Delstudie II omfattar en liknande undersökning med processvariabler som ströavstånd och inverkan av konditioneringssteg på virkesdeformationer. Även högtemperaturtorkning i LTU:s labtork ingår för jämförelse.

  • 50.
    Morén, Tom
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Heat and Mass Transfer during Sapwood Drying above the FSP: Consequences for Kiln Drying2000In: 6th international IUFRO wood drying conference on wood drying research and technology for sustainable forestry beyond 2000., Marcel Dekker Incorporated , 2000Conference paper (Refereed)
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