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  • 701.
    Trischler, Johann
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Dorn, Micheal
    Department of Building Technology, Linnæus University.
    Effect of temperature during vital gluten adhesive preparation and application on shear-bond strength2018Inngår i: Journal of Adhesion Science and Technology, ISSN 0169-4243, E-ISSN 1568-5616, Vol. 32, nr 4, s. 448-455Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    If protein-based adhesives are to become a competitive bio-based alternative to synthetic adhesives, the preparation and application methods have to be considerable improved to reduce process time and thereby improve the economy of the adhesive system. The purpose of this study was to investigate the impact of the temperature during preparation and application on the shear-bond strength of an adhesive based on vital gluten for use in wood applications. Vital gluten was used in its natural form and mixed with water of different temperatures (preparation temperature 0 °C or 20 °C), and applied on beech veneer at different temperature (application temperature –10, 20, 60 and 100 °C). Tensile shear-bond strength samples were prepared and tested according to EN 205. The results showed that an increase in veneer temperature during application of the adhesive led to a decrease in the shear-bond strength, but that the preparation temperature of the adhesive had no influence on the strength.

  • 702.
    Trischler, Johann
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Luleå University of Technology.
    Nuszkowski, Kalle
    Linnéuniversitetet, Fakulteten för konst och humaniora (FKH), Institutionen för design (DE).
    The use of gluten adhesive and removable surface finishes in rebyblable furniture panels2015Inngår i: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 11, nr 4, s. 613-618Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A general problem in the recycling of furniture is that different materials and components are included within a single piece of furniture. Not only is the furniture built of components such as wood, leather, textiles, foams, steel and others but the wood component is also very often a composite made of wood, adhesives and functional additives such as water repellents or chemical substances as surface treatments. Sometimes these additives make cost-effective recycling of the composite wood difficult because of problems related to the separation of the components. The purpose of this study was to present an alternative product design for wood-based panels i.e. particleboards, which reduces or avoids many of the problems in the recycling of wood-based panels used in furniture. The results show that it is possible to produce wood-based panels in a way that facilitates the recycling of these panels although there are still some challenges which have to be dealt with. The concept as such seems to be promising. 

  • 703.
    Trischler, Johann
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Thörnqvist, Thomas
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    An approach to estimate the productivity of various species on sites in Sweden by choosing individual climate and productivity values and the MIAMI-model with modifications.2013Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The literature contains a large variety of bioclimate, climate, biometric models for estimating the production of different species or stands under specific conditions for a defined site, or general models giving a worldwide overview of a single species. Depending on the model used, the amount of input-data varies considerable and is often related to a large investment in time and money.

    The purpose of this study was to create a model to estimate the productivity of various species of interest for biomass production using only easy available input data defining the site conditions. Further, if the site-specific input-data is the same for all species, the model allows a comparison of different species on a single site. For this approach, the MIAMI-model of Lieth et al. was used as basic model with some modifications.

    This modified model differs from recently developed models regarding the combination of species-unspecific site data and the species-specific productivity data. As the site data change with geographical location, easy handling data are profitable. The species-specific data require more extensive investigation, but once established as a database they can be used for all sites without changes. Mean annual temperature and mean annual precipitation were chosen as site-defining data and the mean annual temperature of the native distribution area of each species in combination with the highest biomass production found in the literature were chosen as the species-specific data. This combination makes this model very efficient to estimate the productivity of various species on different sites once the database is established.

    This first version of the model is restricted to sites in Sweden where changes in soil and groundwater level are relatively small. Vegetation is then mainly controlled by energy input expressed for example as temperature or irradiation. As the maximum biomass production is estimated, lower nutrient and water supplies in the soil lead primary to a decrease in biomass production, but this negative impact can be influenced by culture and treatment such as fertilising which is common in conventional agriculture. When extended to other regions with a more Mediterranean climate, for example, the impact of soil, water-storage and distribution of precipitation has to be evaluated first and if necessary included in the model formulation.

    A validation of this model with data from the literature on the one hand and data estimated by another model on the other hand showed that it seems to be possible to use the model for purposed suggested here.

  • 704.
    Trischler, Johann
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Luleå Univeristy of Technology.
    Thörnqvist, Thomas
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Evaluating the Competition of Lignocellulose Raw Materials for their Use in Particleboard Production, Thermal Energy Recovery, and Pulp- and Papermaking2014Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 9, nr 4, s. 6591-6613Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is increasing competition for raw materials between particleboard production, thermal energy recovery, and pulp-and papermaking. According to different scenarios, the consumption of lignocellulosic raw materials is increasing, which means that the competition is increasing. The primary production of lignocellulosic raw material in some regions may therefore reach the limit of sustainability; i.e., the lignocellulosic raw material must be used more efficiently to reduce the risk of a shortage. The physical and chemical properties of the lignocellulosic raw material of selected species have therefore been surveyed, and the raw material properties that are important for each of the three competitors have been defined. The aim of the study is to characterise the lignocellulosic raw materials according to the three competing users and to show whether they are high or low in competition. As methods, a relative ranking of the species regarding their raw material properties and regarding the requirements of the competitors as well as cluster analysis were chosen. The results show that the most favourable raw materials are from coniferous species, while monocotyledon species show an opposite trend.

  • 705. Trovatti, E.
    et al.
    Cunha, A. Gisela
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Carvalho, A. J. F.
    Gandini, A.
    Furan-modified natural rubber: A substrate for its reversible crosslinking and for clicking it onto nanocellulose2017Inngår i: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, Vol. 95, s. 762-768Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The conventional vulcanization process applied to elastomers is irreversible and hinders therefore their useful recycling. We demonstrate here that natural rubber can be reversibly crosslinked via the Diels-Alder coupling of furan and maleimide moieties. The furan-modified natural rubber used in this strategy was also exploited to bind it to maleimide-modified nanocellulose, thus generating a covalently crosslinked composite of these two renewable polymers.

  • 706.
    Tuominen, Mikko
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Funktionella ytbeläggningar på trä/ Functional multilayer coatings to improve properties of wood2016Rapport (Annet vitenskapelig)
    Abstract [sv]

    Report on the Troëdsson Postdoc-project 2013‒2015.

  • 707.
    Turesson, Jonas
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Diagonal compression of Cross-Laminated Timber2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Twelve blocks of Cross Laminated Timber (CLT) were built, tested and simulated. Three types of blocks with different laminate directions in the middle/second layers were used: 0/30/0, 0/45/0 and 0/90/0. Simulations with three-dimensional quadratic orthotropic linear elastic finite elements were conducted. The goal was to compare tested in-plane shear stiffnesses for CLT blocks made from Norway Spruce (Picea abies) boards of C24 quality with a finite element (FEM) simulated block stiffness. Three-layer CLT were studied with block dimensions of 600 x 600 x 45 mm. The first and last layer laminate directions were assumed to be 0. The middle layer laminate directions were 30, 45 and 90. A 1 mm gap was assumed between the side edges. The glued contact surfaces were assumed to be perfectly glued with rigid glue in the simulations. In the practically tested blocks a PVAc D2 classified glue was used. All blocks were simulated and tested in the same loading arrangement as the practical test set-up. The blocks were compressed in the diagonal direction. Blocks of 0/30/0 and 0/45/0 were compressed twice, once over each diagonal. The 0/90/0 blocks were compressed over one diagonal. A total of 19 practical compression tests was performed; in all cases, the displacements were measured in the force- and orthogonal direction. The stiffest loading case, measured in the force direction, was the loading arrangement 0/45/0-A. The weakest loading case, measured in the force direction, was the loading arrangement 0/30/0-B. The same result could be concluded from the FEM simulations. The calculated stiffness in the loading direction was between 1.21 – 1.87 times larger than the measured stiffness. The models pressed in the “weakest” direction gave the largest difference between the simulated and measured stiffness.

  • 708. Uetimane, Ernesto, Jr.
    et al.
    Allegretti, Ottaviano
    Terziev, Nasko
    Söderström, Ove
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Application of non-symmetrical drying tests for assessment of drying behaviour of ntholo (Pseudolachnostylis maprounaefolia PAX)2010Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 64, nr 3, s. 363-368Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Experiments concerning drying behaviour of ntholo (Pseudolachnostylis maprounaefolia PAX) were conducted to find a suitable drying schedule. Two non-symmetrical drying (NSD) tests were carried out to determine the drying behaviour of ntholo in terms of drying rate and stress behaviour. A tentative drying schedule was selected for comparison of the test results with those of similar tests with other known species. The schedule was tested in a laboratory kiln on 28-mm thick boards. According to both NSD tests and laboratory tests, ntholo dries easily but slowly. The laboratory drying lasted 266 h and achieved standard drying quality characterised by 8.9% moisture content, a moisture gradient of 1.2% and a case-hardening (gap) of 1.2 mm. Twist was the largest deformation with 3.4 mm per 1000 mm on average. The assigned schedule provided standard drying quality and it could be tested further in industrial kilns.

  • 709.
    Umoru, Joseph Adejo
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Characteristics assessment of aspen logs used in the production of matches2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Aspen (Populus tremula L.) accounts for about 2% of the total wood stock in Sweden. Sawmills use only a small part (about 5,000 m³fub) of round wood aspen per year. Since there are no Swedish gradings and design values for aspen, no aspen is used for structural purposes. This also applies to other hardwood trees in Sweden. Aspen is mainly used for pulp and paper with a mass consumption of 800,000 m³fub per year of which about 50% is imported. Most imported aspen is from Russia and the Baltics. The other major use of aspen is in match industries. Consumption for matches amounts to approximately 30,000 m³fub per year in Sweden.

    The aim of the research work was to increase knowledge on the wood quality of aspen used in the production of matches. Aspen (Populus tremula L.) logs were collected from two different sites in Sweden and a non-destructive tools weas used to estimate the modulus of elasticity in logs. To measure the dynamic modulus of elasticity (MOEdyn), Fakopp resonance log grader used. Other properties like density and moisture content were measure and were correlated with the MOEdyn values in order to identify the site that has a better log quality. Besides, horizontal and vertical variation of different wood properties were measured and compared within and between trees from two different sites in order to justify the variation of log quality. A total of 20 trees from Askaremåla and Vimmerby, Sweden were felled and used in this study. From each tree, 3 m long logs were sampled from each base, middle and top. After that, non-destructive evaluations were performed in those logs. Besides, 5 cm thick discs were collected in every tree height (base, middle and top) to measure horizontal and vertical variations.

    This study shows that there were differences in MOEdyn between and within trees. It was evident that trees collected from Vimmerby had a better log property than that in Askaremåla. Using non-destructive tools, it is possible to sort out quality logs for the production of Swedish matches.

  • 710. Vahtikari, Katja
    et al.
    Rautkari, Lauri
    Noponen, Tuula
    Lillqvist (nee Laine), Kristiina
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Hughes, Mark
    The influence of extractives on the sorption characteristics of Scots pine (Pinus sylvestris L.)2017Inngår i: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 52, nr 18, s. 10840-10852Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The sorption behaviour of extracted and un-extracted Scots pine (Pinus sylvestris L.) heartwood was analysed using dynamic vapour sorption apparatus. In addition to the sorption isotherm and hysteresis, the moisture increments and decrements were determined as well as the rate of sorption. Parallel exponential kinetics model was used for further analysis. The effect of cyclic humidity loading on the sorption characteristics was studied by exposing samples to ten repeated sorption cycles and by determining the amount of accessible hydroxyl (OH) groups before and after the cyclic humidity loading. Removal of extractives led to an increase in EMC both in adsorption and in desorption. Hysteresis decreased due to the removal of extractives. Cyclic humidity loading reduced the sorptive capacity of wood material for both extracted and un-extracted wood, but was more pronounced in un-extracted wood. However, despite the decrease in the sorptive capacity, the amount of accessible OH groups increased after ten repeated dry-humid cycles.

  • 711. van Blokland, J
    et al.
    Adamopoulos, S
    Olsson, A
    Oscarsson, J
    Bending properties and strain fields around knots in thermally modified timber2018Inngår i: / [ed] Jos Creemers, Thomas Houben, Bôke Tjeerdsma, Holger Militz and Brigitte Junge, 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Thirty-two (32) boards of Norway spruce with cross-sectional dimensions of 145×45 mm2 were first tested non-destructively in a four-point static bending test, were then thermally modified according to the ThermoWood® process, and were finally tested destructively in the mentioned test set up. For one of these boards, the 2D strain fields occurring due to pure bending were recorded, both before and after thermal modification, over the surface of a knotty part of the board using a non-contact optical deformation measurement system. The objectives were to get more insight into the static bending behaviour of thermally modified timber (TMT), specifically with regard to the local and global modulus of elasticity (MOE) and their respective relationship to bending strength, and the strain development around a cluster of knots. The bending strength was significantly reduced by thermal treatment, whereas the effect on the MOEs was limited. Linear regression analyses demonstrated that bending strength of TMT can be predicted by employing stiffness as indicating property. Strain field measurements showed that at the examined levels of loading the quantity and distribution of strains in a knotty area were not influenced by thermal modification. It was therefore suggested that the influence of thermal modification on global stiffness, as well as on local stiffness around knots, is limited.

  • 712.
    van Blokland, Joran
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Olsson, Anders
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY). Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Oscarsson, Jan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Källander, Björn
    Swedish Wood.
    Evaluation of non-destructive test methods to predict bending properties of thermally modified timber2018Inngår i: 2018 World Conference on Timber Engineering (WCTE),August 20-23, 2018, Seoul, Republic of Korea, National Institute of Forest Science (NIFoS) , 2018, s. 8-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Thermally modified wood is available through a number of manufacturers in Europe on today’s market for interior and exterior building products. Thermal modification of wood allows for improvement of dimensional stability and durability, but a considerable decrease in strength properties occurs. Despite this loss in strength, thermally modified wood shows potential to be further exploited in structures exposed to loading. For such applications, accurate prediction of its static bending behaviour is essential. This paper studies the applicability of two different non-destructive test (NDT) techniques in estimating the bending properties of thermally modified timber (TMT). The study was done on 100 Norway spruce logs. One hundred (100) boards (i.e. one from each log) were thermally modified and the mirrored 100 boards were used as controls. After modification, resonance-based and time-of-flight measurements of axial wave velocity were carried out. Subsequently, all 200 boards were bent to failure following European standard EN408. This study shows that although TMT has a lower bending strength than unmodified timber, predictions of bending strength and stiffness using the NDT techniques are possible and with sufficient accuracy. The resonance-based method gave better predictions of the bending properties of TMT in respect to time-of-flight method.

  • 713. Van den Bulcke, Jan
    et al.
    Wernersson, Erik L. G.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för visuell information och interaktion. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Bildanalys och människa-datorinteraktion.
    Dierick, Manuel
    Van Loo, Denis
    Masschaele, Bert
    Brabant, Loes
    Boone, Matthieu N.
    Van Hoorebeke, Luc
    Haneca, Kristof
    Brun, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för visuell information och interaktion. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Bildanalys och människa-datorinteraktion.
    Luengo Hendriks, Cris L.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för visuell information och interaktion. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Bildanalys och människa-datorinteraktion.
    Van Acker, Joris
    3D tree-ring analysis using helical X-ray tomography2014Inngår i: Dendrochronologia, ISSN 1125-7865, E-ISSN 1612-0051, Vol. 32, nr 1, s. 39-46Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The current state-of-the-art of tree-ring analysis and densitometry is still mainly limited to two dimensions and mostly requires proper treatment of the surface of the samples. In this paper we elaborate on the potential of helical X-ray computed tomography for 3D tree-ring analysis. Microdensitometrical profiles are obtained by processing of the reconstructed volumes. Correction of the structure direction, taking into account the angle of growth rings and grain, results in very accurate microdensity and precise ring width measurements. Both a manual as well as an automated methodology is proposed here, of which the MATLAB (c) code is available. Examples are given for pine (Pinus sylvestris L), oak (Quercus robur L) and teak (Tectona grandis L.). In all, the methodologies applied here on the 3D volumes are useful for growth related studies, enabling a fast and non-destructive analysis.

  • 714. Varshoee, Ali
    et al.
    Hosseinpourpia, Reza
    Soltani, Mojtaba
    Talaeipoor, Mohammad
    The Effect of Coupling Agent on Water Absorption Property of Natural Fiber-Cement Nanocomposites2011Inngår i: Iranian Journal of Sciences and Techniques in Natural Resources, Vol. 6, nr 2, s. 127-137Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [fa]

    این تحقیق به منظور بررسی تاٌثیر ماده جفت کننده بر خصوصیات میکروسکوپی و جذب آب در نانو کامپوزیتهاي ساخته شده از الیاف دورریز خمیر کاغذ سولفیت و سیمان انجام گرفته است. در این پژوهش هشت تیمار شامل تاٌثیر دو سطح ماده جفتکننده بر پایه آمینو سیلان (0 و6 درصد وزنی الیاف) و چهار سطح نانو سیلیس (0 ،5/0 ،1 و 3 درصد جایگزینی وزنی سیمان) به عنوان عوامل متغیر و میزان الیاف و آب به ترتیب در سطح 10 درصد و نسبت یک به یک وزنی سیمان ثابت، بر خصوصیت جذب آب نمونه هاي ساخته شده مورد بررسی قرار گرفت. کلیه نمونه ها مطابق با استاندارد Part: 1881 BS 5 1983-122 در سه مرحله جامد، مایع و اختلاط نهایی ساخته و مورد آزمایش قرار گرفتند. تصاویر میکروسکوپی SEM جهت بررسی خواص ریز ساختاري کامپوزیتها از نمونه ها تهیه شد. نتایج به دست آمده نشان داد که با افزایش مقدار نانو ذرات سیلیس، جذب آب در مقایسه با نمونه شاهد کاهش یافت، همچنین افزودن ماده جفت کننده موجب افزایش جذب آب گردید. از طرفی اثر متقابل نانوذرات سیلیس و ماده جفت کننده در مقایسه با نمونههاي شاهد که حاوي مقدار 10 درصد الیاف آزبست بودهاند، نشان دهنده کاهش میزان جذب آب بوده است. نمونههاي حاوي 3 درصد نانو ذرات سیلیس و 6 درصد ماده جفتکننده داراي کمترین میزان جذب آب بوده اند. همچنین تصاویر SEM حاکی از بهبود ریزساختاري نانوکامپوزیتها با افزودن ماده جفت کننده بود.

  • 715. Voulgaridis, E
    et al.
    Karastergiou, S
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Passialis, C
    Kortsalioudakis, N
    Koutsianitis, D
    Foti, D
    Voulgaridou, E
    Effect of laser drilling on the mechanical properties and impregnation of fir and spruce wood2015Konferansepaper (Fagfellevurdert)
  • 716. Voulgaridis, E
    et al.
    Passialis, C
    Adamopoulos, Stergios
    Wood quality characterization in black locust of different origin2000Inngår i: 3rd Workshop of COST Action E10: Wood properties for Industrial Use “Measuring of wood properties, grades and qualities in the conversion chains and global wood optimization”, 19-21 June, Espoo, Finland, 2000, s. 147-162Konferansepaper (Annet vitenskapelig)
  • 717. Voulgaridis, Elias
    et al.
    Adamopoulos, Stergios
    Karastergiou, Sotirios
    Passialis, Costas
    Koutsianitis, Dimitrios
    Kortsalioudakis, Nathanail
    Petrakis, Panagiotis
    Moustaizis, Stavros
    Effects of laser drilling on mechanical properties and impregnability of fir and spruce wood2015Inngår i: Innovation in Woodworking Industry and Engineering Design, ISSN 2367-6663, nr 1, s. 14-22Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fir (Abies borisii regis) and spruce (Picea excelsa) wood specimens, 2 × 2 cm in cross section and 34 cm long, were prepared with true radial and tangential surfaces. All lateral surfaces of the specimens were drilled by laser to a depth of 4 mm (1/5 of specimen thickness) with two drilling patterns (distance between holes 1 × 1 cm and 1 × 2 cm). ). After drilling, the mechanical strength of wood (MOE, MOR, axial compression, toughness) was determined and compared with non-drilled controls. MOE was not affected by the laser drilling, MOR was significantly increased, axial compression was increased and toughness was decreased but not significantly. The overall results imply that strength properties do not decline by the laser drilling. Furthermore, wood specimens were impregnated with rape oil and CCB preservatives by applying vacuum (0.6 mmHg) and pressure (1,5 bars) for 15 minutes and 30 minutes, respectively. The results showed that both drilling patterns improved the retention and penetration of preservatives in fir and spruce wood specimens and, thus, are encouraging for further evaluating the drilling effects on the liquid permeability of these refractory to impregnation species. This effect was more pronounced in fir than in spruce wood.

  • 718.
    Voulgaridis, Elias
    et al.
    Aristotle University of Thessaloniki, Greece.
    Adamopoulos, Stergios
    Technological Educational Institute of Thessaly, Greece.
    Passialis, Costas
    Aristotle University of Thessaloniki, Greece.
    Foti, Dafni
    Aristotle University of Thessaloniki, Greece.
    Voulgaridou, Eleni
    Aristotle University of Thessaloniki, Greece.
    Properties of gypsum bonded solid bricks manufactured with recovered wood and rubber2013Inngår i: Annual Meeting Prosylva Europe and 16th Panhellenic Forestry Conference , 6-9 October 2013, Thessaloniki, Greece, 2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Utilization of recovered wood fromparticleboard production residues and rubber from waste tires in the manufacture of solid bricks was investigated, using gypsum as bonding media. The manufacturing parameters were: small and large rubber and wood particles, different gypsum/wood/rubber ratios for each fraction (small, large), and different gypsum/water ratios. Cylindrical samples, produced by pouring the mixtures into cylindrical molds, were used for testing compressive strength, thermal conductivity and sound absorption according to standard methods.Compressive strength of all gypsum bonded wood and rubber samples was much lower than the controls, e.g. pure gypsum samples. It was found that the wood samplesand the larger fractions (both rubber and wood) were superior in strength than the rubber samples and small fractions, respectively. A maximum proportion25% of wood or rubber as well the use of reclaimed fibrous materials in the manufacture of samples would probably ensure an acceptable compressive strength. No differences were found among the wood/rubber typesfor thermal conductivity, while particle size and proportion of the materials had no effect. Samples with small wood and rubber particles at the lower proportion (25%) were similar in their sound absorption behaviour.

  • 719.
    Voulgaridis, Elias
    et al.
    Aristotle University of Thessaloniki, Greece.
    Passialis, Costas
    Aristotle University of Thessaloniki, Greece.
    Adamopoulos, Stergios
    Technological Educational Institute of Larissa, Greece.
    ΑΝΑΓΝΩΡΙΣΗ ΞΥΛΙΝΩΝ ΕΥΡΗΜΑΤΩΝ ΑΠΟ TON ΤΑΦΙΚΟ ΤΥΜΒΟ ΤΗΣ ΜΙΚΡΗΣ ΔΟΞΙΠΑΡΑΣ-ΖΩΝΗΣ: Identification of the wooden finds from the Tumulus of Mikri Doxipara-Zoni2010Inngår i: ΑΛΟΓΑ ΚΑΙ ΑΜΑΞΕΣ ΣΤΟΝ ΑΡΧΑΙΟ ΚΟΣΜΟ: ΠΡΑΚΤΙΚΑ ΕΠΙΣΤΗΜΟΝΙΚΗΣ ΣΥΝΑΝΤΗΣΗΣ ΟΡΕΣΤΙΑΔΑ 30 ΣΕΠΤΕΜΒΡΙΟΥ 2006: Horses and Wagons in the Ancient World: Proceedings of One Day Scientific Meeting, Orestiada-Greece September 30, 2006 / [ed] Diamantis Triantafyllos, Domna Terzopoulou, Νομαρχία Έβρου , 2010, s. 151-173Konferansepaper (Annet vitenskapelig)
  • 720.
    Voulgaridis, Elias
    et al.
    Aristotle University, Greece.
    Passialis, Costas
    Aristotle University, Greece.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Foti, Dafni
    Aristotle University, Greece.
    Voulgaridou, Eleni
    Aristotle University, Greece.
    ΠΑΡΑΓΩΓΗ ΚΑΙ ΙΔΙΟΤΗΤΕΣ ΠΕΙΡΑΜΑΤΙΚΩΝ ΠΛΙΝΘΩΝ ΕΣΩΤΕΡΙΚΗΣ ΤΟΙΧΟΠΟΙΙΑΣ ΑΠΟ ΓΥΨΟ ΚΑΙ ΑΝΑΚΥΚΛΟΥΜΕΝΑ ΥΛΙΚΑ ΞΥΛΟΥ ΚΑΙ ΕΛΑΣΤΙΚΩΝ ΟΧΗΜΑΤΩΝ: [ Production and properties of experimental bricks for interior walls from gypsum and recycled materials of wood and rubber ]2017Inngår i: ΠΡΑȀΤǿȀΑ : 18ου Πανελλήνιου Δασολογικού Συνεδρίου : “Η Ελληνική Δασοπονία μπροστά σε σημαντικές προκλήσεις: αειφορική διαχείριση δασών, δασικοί χάρτες, περιβαλλοντικές τεχνολογίες – δικτύωση και προστασία φυσικού περιβάλλοντος”: & International Workshop : “Information Technology, Sustainable Development, Scientific Network & Nature Protection” : 8-11 Οκτωβρίου 2017, ΕΔΕΣΣΑ ΠΕȁȁΑΣ, Περιοχή Βαρόσι, Hellenic Forestry Society , 2017, s. 315-323Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Τhe manufacturing and testing of gypsum bonded solid bricks with wood chips from particleboard production residues and rubber and textile fibers from waste tires was investigated. The recovered rubber and wood materials were mixed in gypsum/water solutions for the fabrication of standard solid bricks with six holes by using appropriate molds. After drying, the compressive strength, the thermal conductivity, the air-flow resistance, the sound absorption coefficient and the emissions of volatile organic compounds (VOC) of the bricks were determined. The compressive strength of solid bricks was much greater than that required in interior walls. The bricks showed a better thermal insulation than both the extruded and pressed house bricks but lower than the insulating bricks. Emissions of volatile organic compounds of bricks were at acceptable levels according to regulations for construction products. The sound absorption coefficient of the solid bricks was 0,72 for the frequency of 1 kHz and decreased with increasing frequency. In addition, information on the raw materials and production cost are given.

  • 721. Voulgaridis, Elias
    et al.
    Passialis, Costas
    Adamopoulos, Stergios
    Triantafyllos, D
    Identification of wood and charcoal specimens from the ancient tomb of Mikri Doxipara-Zoni, Evros Prefecture2008Inngår i: National Archaeological Conference, March 13-15, Thessaloniki, Greece, 2008Konferansepaper (Annet vitenskapelig)
  • 722.
    Voulgaridis, Elias
    et al.
    Aristotle University of Thessaloniki, Greece.
    Passialis, Costas
    Aristotle University of Thessaloniki, Greece.
    Karastergiou, Sotirios
    Technological Educational Institute of Thessaly, Greece.
    Adamopoulos, Stergios
    Technological Educational Institute of Thessaly, Greece.
    Kakaras, Ioannis
    Technological Educational Institute of Thessaly, Greece.
    Foti, Dafni
    Aristotle University of Thessaloniki, Greece.
    Koutsianitis, Dimitrios
    Aristotle University of Thessaloniki, Greece.
    Voulgaridou, Eleni
    Aristotle University of Thessaloniki, Greece.
    Effect of laser drilling on impregnability of fir (Abies borisii regis) and spruce (Picea excelsa) wood2014Inngår i: Wood Structure, Properties and Quality – 2014: 5th RCCWS International Symposium, Moscow State University Press, 2014, s. 51-56Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Fir and spruce wood specimens, 2×2 cm in cross section and 34 cm long, were pre-pared with true radial and tangential surfaces. All lateral surfaces of the wood specimens were drilled by laser beams to a depth of 0,4 cm (1/5 of specimen thickness) with two drilling patterns (distance between holes 1×1 cm and 1×2 cm) in order to improve the wood permea-bility of these refractory to impregnation species. After drilling and assessing the drilling ef-fect on mechanical properties of wood, wood specimens, 10 cm long, were impregnated with oil and CCB preservatives by using vacuum (0,6 mmHg) and pressure (1,5 bar) for 15 minutes and 30 minutes, respectively. The effects of the two laser drilling patterns on impreg-nability of fir and spruce wood specimens were measured and assessed. The results showed that both drilling patterns created by laser beams on all lateral surfaces of fir and spruce wood specimens at 0,4 mm depth improved the retention and penetration of preservatives in fir and spruce wood specimens. This effect was more pronounced in fir than in spruce. Between the two drilling patterns, the pattern with distances between holes 1×1 cm was more effective than that with distances 1×2 cm, in both species tested.

  • 723.
    Voulgaridis, Elias
    et al.
    Aristotle Univ Thessaloniki, Greece.
    Passialis, Costas
    Aristotle Univ Thessaloniki, Greece.
    Negri, Martino
    Ivalsa Cnr, Trees & Timber Inst, Italy.
    Adamopoulos, Stergios
    Technol Educ Inst Larissa, Greece.
    Shear bond strength of black locust wood glued with three adhesive systems2012Inngår i: Wood research, ISSN 1336-4561, Vol. 57, nr 3, s. 489-496Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Black locust wood was bonded with three commercial adhesives (PVAc, PU, epoxy) and tested for its shear bond strength against process (treatments I and II) and surface parameters (radial, tangential, roughness). For treatment I (applied pressure 8 bar, press time 1.5 h, curing time 24 h), the mean shear bondstrength was found to be 6.95 N.mm(-2), 5.54 N.mm(-2) and 10.53 N.mm(-2) corresponding to the three adhesives tested, respectively. Increase in press and curing time in treatment II (press time 3 h, curing time 7 days) significantly improved the gluing performance of adhesives, 9.58 N.mm(-2) for PVAc, 13.32 N.mm(-2) for PU and 15.03 N.mm(-2) for epoxy. Surface of gluing (radial, tangential) did not affect the shear bond strength significantly. Failure within wood was found to be up to 40 % for treatment I (PVAc, epoxy) and up to 85 % for treatment II (epoxy). Positive linear regressions were calculated between shearbond strength and wood failure only for PU and epoxy adhesives. Shear bond strength was not related to surface roughness for any adhesive.

  • 724.
    Wagner, Leopold
    et al.
    Vienna University of Technology, Austria.
    Almkvist, Gunnar
    Swedish University of Agricultural Sciences .
    Bader, Thomas K.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY). Vienna University of Technology, Austria.
    Bjurhager, Ingela
    Uppsala University.
    Rautkari, Lauri
    Aalto University, Finland.
    Gamstedt, E. Kristofer
    Uppsala University.
    The influence of chemical degradation and polyethylene glycol on moisture-dependent cell wall properties of archeological wooden objects: a case study of the Vasa shipwreck2016Inngår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 50, nr 6, s. 1103-1123Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cell wall measures allow for direct assessment of wood modification without the adverse effect of varying density and microstructure. In this study, cell wall properties of recent and archeological oak wood from the Vasa shipwreck were investigated for cell wall stiffness, hardness and creep with respect to effects of chemical degradation, impregnation with a preservation agent, namely polyethylene glycol, and moisture. For this purpose, nanoindentation tests were performed at varying relative humidity, leading to different moisture contents in the wood samples. Concurrently, microstructural and chemical characterization of the mate- rial was conducted. Impregnated and untreated recent oak wood showed a softening effect of both moisture and preservation agent at the wood cell wall level. On the contrary, increased stiffness was found for non-impregnated Vasa oak, which can be explained by aging-related modifications in cell wall components. These effects were counteracted by the softening effect of polyethylene glycol in the impregnated Vasa material, where a lower overall stiffness was measured. The reverse effect of the preservation agent and moisture, namely increased indentation creep of the cell wall material, was revealed. The loss of acetyl groups in the hemicelluloses explained the decreased hygroscopicity of the Vasa oak. In the impregnated Vasa oak, this effect seemed to be partly counteracted by the presence of low-molecular polyethylene glycol contributing to higher hygroscopicity of the cell wall. Thus, the higher overall sorptive capacity of the impregnated Vasa material, with respect to the non-impregnated material, was detected, which has resulted in a sorptive behavior similar to that of recent oak wood. The proposed approach requires only small amounts of material, making it especially suitable for application to precious historical wooden artifacts. 

  • 725. Wagner, Leopold
    et al.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Cell Wall Properties of Archaelogical Oak Wood from the Vasa Shipwreck: A Nanoindentation Study2015Inngår i: 32nd Danubia-Adria-Symposium (DAS 32), Zilina, Slovakia, 2015, s. 162-163Konferansepaper (Annet vitenskapelig)
  • 726.
    Wagner, Leopold
    et al.
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Auty, David
    Université Laval, Canada.
    de Borst, Karin
    University of Glasgow, UK.
    Control Parameters for Within-Tree Variability of Wood Stiffness at Different Length Scales: Multiscale Modeling and Experimental Investigations2012Inngår i: COST Action FP0802 - Experimental and Computational Micro-Characterization Techniques in Wood Mechanics, Edinburgh, UK, 2012, s. 72-73Konferansepaper (Annet vitenskapelig)
  • 727.
    Wagner, Leopold
    et al.
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Auty, David
    University of Aberdeen, UK.
    de Borst, Karin
    University of Glasgow, UK.
    Key parameters controlling stiffness variability within trees: a multiscale experimental–numerical approach2012Inngår i: Trees, ISSN 0931-1890, E-ISSN 1432-2285, Vol. 27, nr 1, s. 321-336Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Microstructural properties of wood vary considerably within a tree. Knowledge of these properties and a better understanding of their relationship to the macroscopic mechanical performance of wood are crucial to optimize the yield and economic value of forest stocks. This holds particularly for the end-use requirements in engineering applications. In this study the microstructure–stiffness relationships of Scots pine are examined with a focus on the effects of the microstructural variability on the elastic properties of wood at different length scales. For this purpose, we have augmented microstructural data acquired using SilviScan-3™ (namely wood density, cell dimensions, earlywood and latewood proportion, microfibril angle) with local measurements of these quantities and of the chemical composition derived from wide-angle X-ray scattering, light microscopy, and thermogravimetric analysis, respectively. The stiffness properties were determined by means of ultrasonic tests at the clear wood scale and by means of nanoindentation at the cell wall scale. In addition, micro-mechanical modeling was applied to assess the causal relations between structural and mechanical properties and to complement the experimental investigations. Typical variability profiles of microstructural and mechanical properties are shown from pith to bark, across a single growth ring and from earlywood to latewood. The clear increase of the longitudinal stiffness as well as the rather constant transverse stiffness from pith to bark could be explained by the variation in microfibril angle and wood density over the entire radial distance. The dependence of local cell wall stiffness on the local microfibril angle was also demonstrated. However, the local properties did not necessarily follow the trends observed at the macroscopic scale and exhibited only a weak relationship with the macroscopic mechanical properties. While the relationship between silvicultural practice and wood microstructure remains to be modeled using statistical techniques, the influence of microstructural properties on the macroscopic mechanical behavior of wood can now be described by a physical model. The knowledge gained by these investigations and the availability of a new micromechanical model, which allows transferring these findings to non-tested material, will be valuable for wood quality assessment and optimization in timber engineering.

  • 728. Wagner, Leopold
    et al.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    de Borst, Karin
    Mechanical Properties of Scots Pine (Pinus sylvestris L.) Cell Walls After Fungal Degradation: Multiscale Micromechanical Modeling and Experimental Validation2012Konferansepaper (Annet vitenskapelig)
  • 729.
    Wagner, Leopold
    et al.
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    de Borst, Karin
    University of Glasgow, UK.
    Micromechanical Modelling of Degration Processes in Wood2014Inngår i: 11th. World Congress on Computational Mechanics (WCCM XI), 5th. European Conference on Computational Mechanics (ECCM V), 6th. European Conference on Computational Fluid Dynamics (ECFD VI), July 20 - 25, 2014, Barcelona, Spain, Barcelona, Spain, 2014Konferansepaper (Annet vitenskapelig)
  • 730. Wagner, Leopold
    et al.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    de Borst, Karin
    Nanoindentation of Wood Cell Walls: Effects of Different Sample Preparation Methods2013Konferansepaper (Annet vitenskapelig)
  • 731.
    Wagner, Leopold
    et al.
    University of Technology, Austira.
    Bader, Thomas K.
    University of Technology, Austira.
    de Borst, Karin
    University of Glasgow, UK.
    Nanoindentation of wood cell walls: effects of sample preparation and indentation protocol2014Inngår i: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 49, nr 1, s. 94-102Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nanoindentation has become a valuable tool in wood science. It enables to examine the mechanical properties of the wood cell walls, which are polymeric, multi-layered structures with typical thicknesses of a few micrometers. Despite the intensive use of the method for the characterization of wood cell walls, it is not entirely clear yet how the measurement results may be affected by the way the sample is prepared and the indentation is carried out. This manuscript contributes to clarify these issues, by presenting indentation data for a variety of sample preparation techniques and indentation protocols, and by critically evaluating the observed differences of the obtained indentation moduli and hardnesses. Investigations covered the effect of different embedding materials, including testing of non-embedded cell walls, and of repeated exposure to high temperatures during harsh drying before the indentation test. Moreover, potential edge effects were studied when the indentation size approaches the width of the individual cell wall layers. Using different embedding materials as well as testing non-embedded cell walls did not lead to significant changes in the measured properties. Due to damage during the sample preparation, non-embedded cell walls tend to show substantially higher experimental scatter. Repeated drying prior to embedding had no significant effect on the resulting moduli and hardnesses. Finally, it was found that reasonable mechanical properties can be extracted from the cell corner middle lamella (CCML), even when the size of the indent approaches the diameter of the CCML.

  • 732. Wagner, Leopold
    et al.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    de Borst, Karin
    Eberhardsteiner, Josef
    Nanoindentation to Study Within-Tree Variability of Wood Cell Wall Stiffness2012Inngår i: 29th DANUBIA-ADRIA SYMPOSIUM on Advances in Experimental Mechanics, September 26-29, Belgrade, Serbia, Belgrade, Serbia, 2012, s. 8-9Konferansepaper (Annet vitenskapelig)
  • 733.
    Wagner, Leopold
    et al.
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    de Borst, Karin
    University of Glasgow, UK.
    Ters, Thomas
    Vienna University of Technology, Austria.
    Fackler, Karin
    Vienna University of Technology, Austria.
    Cell wall properties of softwood deteriorated by fungi: combined chemical analyses, FT-IR spectroscopy, nanoindentation and micromechanical modelling2013Inngår i: Proceedings IRG Annual Meeting, Stockholm: The International Research Group on Wood Protection , 2013Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Mechanical properties of wood are determined by its inherent hierarchical microstructure, starting at the nanometer scale, where the elementary components cellulose, hemicelluloses, and lignin build up the wood cell wall material. Fungi cause degradation and decomposition of these components and, thus, alter the mechanical properties of wood. The aim of this study is to gain new insight into these relationships at the cell wall level, particularly at early stages of degradation, characterized by a mass loss of less than 10 %. Early detection of deterioration is essential during monitoring of timber structures as it may help avoiding subsequent larger scale damages. This contribution presents results of an ambitious experimental programme covering the determination of earlywood/latewood specific compositional data with consistent microstructural and micromechanical properties. Scots pine (Pinus sylvestris L.) sapwood was studied in reference condition and after degradation by brown rot (Gloeophyllum trabeum) and white rot (Trametes versicolor), respectively. Ultrastructural and compositional data were acquired by means of FT-IR spectroscopy and wet chemical analyses. Micro-structural features, such as the microfibril angle, were determined by X-ray diffraction. Mechanical properties of sound and degraded wood cell walls were determined using nanoindentation, yielding the (anisotropic) indentation modulus of the S2 cell wall layer and the cell corner middle lamella of Scots pine tracheids. Aiming at the identification of relationships between ultrastructural and micromechanical characteristics, two different approaches were followed. On the one hand, multivariate data analysis was applied. On the other hand, a multiscale micromechanical model was used to derive causal relationships between structure and (mechanical) function for deteriorated wood. Anisotropic indentation theory allows calculating model predictions for the indentation modulus of the S2 cell wall layer based on measured chemical compositions resulting from the degradation process. Comparing these predictions with the experimental results enables to test hypotheses on possible scenarios of wood cell wall deterioration during fungal attack. Identified relationships between ultrastructural, microstructural, and micromechanical characteristics will be discussed as well as the potential of micromechanical modelling in the analysis of fungal degradation strategies and their effect on the mechanical behaviour. 

  • 734.
    Wagner, Leopold
    et al.
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    de Borst, Karin
    University of Glasgow, UK.
    Consequences of Microbial Decay on Mechanical Properties of Wood Cell Walls2015Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    As a natural material, wood is susceptible to degradation processes, preserving equilibrium between buildup and breakdown of biomass. Microorganisms, such as fungi or bacteria, play a major role in the degradation processes in wood. Their activity depends on the environmental conditions: in ambient conditions fungal degradation is dominant while in waterlogged conditions mainly bacterial degradation occurs. Wood exhibits a hierarchical organization. Thus, mechanical properties of a piece of solid wood depend on its inherent heterogeneous microstructure. Starting from the annual rings, individual wood cells and their cell wall layers can be identified as hierarchical levels. The so-called S2 cell wall layer and the middle lamella between individual wood cells dominate the macroscopic behaviour of wood. Thus the properties of these two layers are of particular interest. Their mechanical properties can be assessed by means of nanoindentation. During nanoindentation, a probe is pushed into a flat sample surface and from the subsequent unloading behavior, material properties, such as the indentation modulus and the indentation hardness, can be determined. In contrast to findings at the macroscopic scale, no stiffness losses were detected in degraded cell wall layers. Even slightly increased stiffness of the S2 layer and the middle lamella were measured in material degraded either by fungi or bacteria. Concurrently, microstructural and chemical analyses of the degraded material were conducted. Both multivariate data analysis as well as micromechanical modeling enables establishing structure-function relationships also for degraded wood cell walls.

  • 735.
    Wagner, Leopold
    et al.
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    de Borst, Karin
    University of Glasgow, UK.
    Fungal degradation of softwood cell walls: Enhanced insight through micromechanical modeling2014Inngår i: International Biodeterioration & Biodegradation, ISSN 0964-8305, E-ISSN 1879-0208, Vol. 93, s. 223-234Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Abstract Fungal degradation is among the greatest hazards for standing trees as well as timber constructions. Herein we aim at gaining more detailed insight into the degradation strategies of wood destroying fungi and the consequences on the mechanical performance of wood. At the macroscale, the occurring losses of mass and of mass density mask effects of altered chemical composition and microstructure. Thus, it is necessary to step down the hierarchical organization of wood to the cell wall scale in order to resolve these changes and their mechanical impact. We present a multiscale micromechanical model which is used to estimate the stiffnesses of the S2 cell wall layer and the compound middle lamella of fungal degraded wood. Data from a detailed chemical, microstructural and micromechanical characterization of white rot and brown rot degraded Scots pine sapwood is analyzed. Comparing predicted cell wall stiffnesses with measured ones confirms the suitability of the approach. The model enables to establish structure–stiffness relationships for fungal degraded wood cell walls and to test hypotheses on yet unknown effects of fungal decay. The latter include the evolution of porosity, modifications of the cell wall polymers resulting in changes of their stiffnesses, as well as increasing cell wall crystallinity. The model predictions in general showed good agreement with the predictions not considering pores in the cell wall. However, this finding does not rule out the formation of porosity. Other degradation related effects like modifications of the cell wall polymers as well as increased crystallinity have the potential to account for stiffness decreases upon the formation of pores.

  • 736.
    Wagner, Leopold
    et al.
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Fackler, Karin
    Vienna University of Technology, Austria.
    Ters, Thomas
    Vienna University of Technology, Austria.
    Nanoindentation and Micromechanical Modeling to Explore the Mechanical Performance of Deteriorated Softwood2011Inngår i: COST Action FP0802 - Experimental and Computational Micro-Characterization Techniques in Wood Mechanics, Helsinki, Finland, 2011, s. 61-62Konferansepaper (Annet vitenskapelig)
  • 737.
    Wagner, Leopold
    et al.
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Ters, Thomas
    Vienna University of Technology, Austria.
    Fackler, Karin
    Vienna University of Technology, Austria.
    de Borst, Karin
    University of Glasgow, UK.
    A combined view on composition, molecular structure, and micromechanics of fungal degraded softwood2015Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 69, nr 4, s. 471-482Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fungal decay alters the composition, microstructure, and mechanical properties of wood cell walls. To understand better the structure-function relationships during fungal decay, selected annual rings of fungal deteriorated Scots pine sapwood were analyzed in terms of their composition, microstructure, and micromechanical properties. The datasets were acquired separately for earlywood and latewood concerning the S2 cell wall layer and the cell corner middle lamella (CCML) and analyzed by means of principal component analysis and partial least squares regression analysis. Links between cell wall stiffness and hardness and the composition and microstructure could be established. Increased mechanical properties in the CCML, as obtained by nanoindentation, were correlated to the degradation of pectins. In the S2 layer, the altered data were related to the degradation of hemicelluloses and lignin modification during fungal decay.

  • 738.
    Wagner, Leopold
    et al.
    Vienna University of Technology, Austria.
    Bos, Clemence
    Vienna University of Technology, Austria ; Institute for applied materials, Germany.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    de Borst, Karin
    University of Glasgow, UK.
    Effect of Water on the Mechanical Properties of Wood Cell Walls: Results of a Nanoindentation Study2015Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 10, nr 3Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The paper presents a nanoindentation study on five different wood species in which the elastic and creep properties of the S2 cell wall layer and the middle lamella were determined. Measurements were carried out at relative humidities (RH) ranging from 10 to 80% as well as underwater. Indentation moduli were found to decrease by about a third in the S2 layer and by about half in the middle lamella between RH of 10 and 80%. Hardness dropped by 50 to 60% in this humidity range in both the S2 layer and the middle lamella. Creep parameters were almost constant up to a relative humidity of 40%, but they increased considerably at higher RH. The most pronounced change of reduced moduli and creep properties occurred between 60 and 80% RH, which is consistent with the expected softening of hemicellulose and amorphous parts of cellulose in this humidity region. Immersion into water resulted in a further decrease of the reduced moduli to about 20 to 30% of their values at 10% RH and to only about 10 to 20% for the hardness. This can be explained by additional softening of the less ordered regions of cellulose.

  • 739. Wagner, Leopold
    et al.
    Bos, Clemence
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Moisture-Dependent Mechanical Properties of Softwood and Hardwood Cell walls: A Nanoindentation Study2014Inngår i: 16th International Conference on Experimental Mechanics (ICEM16), July 7-11, 2014, Cambridge, Cambridge, UK, 2014Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Wood is a hygroscopic material. Increasing moisture decreases the macroscopic mechanical properties of wood. Investigations of the mechanical behaviour of the solid wood substance at the cell wall scale may contribute to an enhanced insight into moisture-mechanics relationships. Wood cells walls are composed of several different layers, of which the S2 layer and the middle lamella (ML) are mechanically most important. Their mechanical properties can be assessed by nanoindentation. Wood of two hardwood species and three softwood species is investigated. Mechanical properties of the S2 layer as well as of the ML are determined at different relative humidity (RH), i.e. at different wood moisture contents (MC).

  • 740. Wagner, Leopold
    et al.
    Bos, Clemence
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Moisture-Dependent Mechanical Properties of Softwood and Hardwood Cell Walls: A Nanoindentation Study2014Inngår i: 31st Danubia-Adria Symposium on Advances in Experimental Mechanics, September 24-27, 2014, Kempten, 2014, s. 151-152Konferansepaper (Annet vitenskapelig)
  • 741. Wagner, Leopold
    et al.
    Fackler, Karin
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Ters, Thomas
    de Borst, Karin
    Fungal Degradation of Scots Pine (Pinus sylvestris L.) Wood: Micromechanical and Microstructural Characterization at the Cell Wall Level2012Inngår i: 7th International Plant Biomechanics Conference, August 20-24, 2012, Clermont-Ferrand, France, Clermont-Ferrand, France, 2012Konferansepaper (Annet vitenskapelig)
  • 742.
    Walford, Brian
    et al.
    Wood Quality and Solid Wood Products Forest Research.
    Ormarsson, Sigurdur
    Prediction of Twist in Poles that Contain Spiral Grain2003Inngår i: IAWPS2003 International Conference on Forest Products, 2003Konferansepaper (Fagfellevurdert)
  • 743.
    Wang, X. A.
    et al.
    Luleå University of Technology.
    Hagman, O.
    Luleå University of Technology.
    Sundqvist, B.
    SP Technical Research Institute of Sweden ; SP Sustainable Built Environment.
    Ormarsson, Sigurdur
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Wan, H.
    Mississippi State University, USA.
    Niemz, P.
    ETH, Switzerland.
    Impact of cold temperatures on the shear strength of Norway spruce & scots pine joints with different glues2016Inngår i: WCTE 2016 - World Conference on Timber Engineering, Vienna University of Technology , 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    As wood construction increasingly uses engineered wood products worldwide, concerns arise about the integrity of the wood and adhesives used. Bondline strength is a crucial issue for engineered wood applications, especially in cold climates. In this study, the impact of cold temperatures on the shear strength of Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) joints (150 mm x 20 mm x 10 mm) bonded with seven commercially available adhesives was studied. The cold temperatures investigated were: 20, -20, -30, -40, -50, and -60 °C. Generally, within the temperature test range, temperature changes significantly affected the shear strength of solid wood and wood joints for both species. As the temperature decreased, the shear strength decreased. PUR adhesive in most cases resulted in the strongest shear strength and MUF adhesive resulted in the weakest. But different adhesives responded differently with Norway spruce and Scots pine.

  • 744.
    Wang, Xiaodong Alice
    et al.
    Luleå University of Technology.
    Björnberg, Jonathan
    Luleå University of Technology.
    Hagman, Olle
    Luleå University of Technology.
    Ahmed, Sheikh Ali
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Wan, Hui
    Mississippi State University, USA.
    Niemz, Peter
    Swiss Federal Institute of Technology in Zurich, Switzerland.
    Effect of Low Temperatures on the Block Shear Strength of Norway Spruce Glulam Joints2016Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, nr 4, s. 9638-9648Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The block shear strength of Norway spruce (Picea abies (L.) Karst.) glulam joints was tested under low temperature. Glulam samples were glued with the three of the most common outdoor structural adhesives. The cold temperatures tested were 20, −20, −30, −40, -50 and −60 °C. Within the temperature test range, the block shear strength of the glulam joints was resistant to the effect of temperature. As the temperature decreased, the joints’ block shear strength did not show any significant change. In most cases, phenol-resorcinol-formaldehyde (PRF) adhesive yielded the strongest block shear strength, while melamine-formaldehyde (MF) adhesive yielded the weakest block shear strength. Melamine-urea-formaldehyde (MUF) adhesive yielded similar results to those of MF adhesives for all temperatures tested. The block shear strengths of the glulam joints with PRF, MUF and MF adhesives were not sensitive to temperature change. The results indicated that PRF, MUF and MF adhesives are stable for outdoor structural engineered wood construction in cold climate. The results also suggest that the SS-EN 14080 (2013) standard for the block shear method may not be the proper standard for testing differences in shear strength at different temperatures. The EN 302-1 (2011) standard could be more suitable for this purpose.

  • 745.
    Wang, Xiaodong (Alice)
    et al.
    Luleå Universoty of Technology.
    Hagman, Olle
    Luleå Universoty of Technology.
    Sundqvist, Bror
    SP Technical Research Institute of Sweden.
    Ormarsson, Sigurdur
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Wan, Hui
    Mississippi State University, USA.
    Niemz, Peter
    ETH Zurich, Switzerland.
    Shear Strength of Scots Pine Wood and Glued Joints in a Cold Climate2016Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, nr 1, s. 944-956Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The impact of cold temperatures on the shear strength of Scots pine (Pinus sylvestris) joints glued with seven commercially available adhesives was studied in this work. The cold temperatures investigated were: 20, -20, -30, -40, and -50 degrees C. Generally, within the temperature test range, the shear strength of Scots pine solid wood and wood joints were more resistant to the effect of temperature than those of Norway spruce. As the temperature decreased, only some of the joints' shear strength significantly decreased. In most cases, PUR adhesive yielded the strongest shear strength and MUF adhesive yielded the weakest shear strength. MF adhesive responded to temperature changes in a similar manner to that of PUR and PVAc adhesives. The shear strengths of wood joints with PRF and EPI adhesives were more sensitive to temperature change. For dynamic tests of shear strength, the values for 12-h and 6-day tests under temperature cycles (-20 and 0 degrees C) were compared. The values for 6-day tests were lower than those for 12-h tests. Therefore, the duration of the samples subjected to the same temperature had a significant impact on shear strength. Our results indicate that PUR adhesive is the most stable; whereas the stability of MUF and PRF adhesives decreased significantly.

  • 746.
    Wang, Xiaodong
    et al.
    Luleå University of Technology.
    Hagman, Olle
    Luleå University of Technology.
    Sundqvist, Bror
    SP Technical Research Institute of Sweden.
    Ormarsson, Sigurdur
    Technical University of Denmark, Denmark.
    Wan, Hui
    Mississippi State University, USA.
    Niemz, Peter
    ETH Zurich.
    Impact of cold temperatures on the shear strength of Norway spruce joints glued with different adhesives2015Inngår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 73, nr 2, s. 225-233Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    As wood construction increasingly uses engineered wood products worldwide, concerns arise about the integrity of the wood and adhesives used. Bondline strength is a crucial issue for engineered wood applications, especially in cold climates. In this study, Norway spruce (Picea abies) joints (150 mm × 20 mm × 10 mm) were bonded with seven commercially available adhesives: polyurethane (PUR), polyvinyl acetate (PVAc), emulsion-polymer-isocyanate (EPI), melamine-formaldehyde (MF), phenol-resorcinol-formaldehyde (PRF), melamine-urea-formaldehyde1 (MUF1), and melamine-urea-formaldehyde2 (MUF2). Each adhesive was tested at six temperatures: 20, −20, −30, −40, −50 and −60 °C. Generally, within the temperature test range, temperature changes significantly affected the shear strength of solid wood and wood joints. As the temperature decreased, the shear strength decreased. PUR adhesive in most cases resulted in the strongest shear strength and MUF adhesive resulted in the weakest. MF and PRF adhesives responded to temperature changes in a similar manner to that of the PUR adhesive. The shear strengths of wood joints with PVAc and EPI adhesives were more sensitive to temperature change. At low temperatures, the variability of shear strengths increased with all adhesives. Percent wood failures of joints bonded with different adhesives in most cases were not sensitive to temperature changes.

  • 747.
    Wang, Zhao
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Recalcitrance of wood to biochemical conversion: feedstock properties, pretreatment, saccharification, and fermentability2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Lignocellulose is an inexpensive and abundant renewable resource that can be used to produce advanced biofuels, green chemicals, and other bio-based products. Pretreatment and efficient enzymatic saccharification are essential features of bioconversion of lignocellulosic biomass. The aims of the research were to achieve a better understanding of the recalcitrance of woody biomass to bioconversion, to explore different pretreatment techniques that can be used to decrease the recalcitrance of the biomass and improve the digestibility of the cellulose, and to investigate by-products of acid pretreatment that cause enzymes and microorganisms to work less efficiently.

    The recalcitrance of wood from aspen, birch, and spruce was investigated before and after acid pretreatment. Before pretreatment, birch exhibited the highest recalcitrance, which was attributed to structural factors. After pretreatment, spruce showed the highest recalcitrance, which was attributed to chemical factors, such as high lignin content. Deacetylation of hybrid aspen in planta by a CE5 acetyl xylan esterase decreased the recalcitrance, and the glucose yield of enzymatic saccharification of non-pretreated wood increased with 27%.

    Pretreatment options based on ionic liquids and steam explosion were further explored. The effects of the anionic constituents of a series of imidazolium-based ionic liquids on pretreatment of aspen and spruce were investigated. [HSO4]− was efficient only for aspen, which was attributed to acid degradation of xylan. [MeCO2]− was efficient for both aspen and spruce, which was attributed to its capability to create a disordered cell wall structure rather than to removal of lignin and hemicellulose. A comparison was made between using sulfuric acid and sulfur dioxide for pretreatment of spruce. Although sulfur dioxide resulted in a pretreatment liquid that was more inhibitory to both enzymes and yeast, it was still superior to pretreatment with sulfuric acid, a phenomenon that was attributed to the particle size of the pretreated material.

    In a comparison of microbial inhibitors in pretreatment liquids from steam explosion of spruce, formaldehyde was found to be the most important inhibitor of yeast. Enzyme inhibition by catalytically non-productive adsorption to lignins and pseudo-lignin was investigated using quantitative proteomics. The results indicate that protein adsorption to pseudo-lignin can be as extensive as adsorption to real lignin. 

    Fulltekst tilgjengelig fra 2019-03-06 00:01
  • 748.
    Wernersson, Erik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Centrum för bildanalys. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datoriserad bildanalys.
    Brun, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Centrum för bildanalys.
    Luengo Hendriks, Cris L.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Centrum för bildanalys. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datoriserad bildanalys.
    Segmentation of Wood Fibres in 3D CT Images Using Graph Cuts2009Inngår i: Image Analysis and Processing – ICIAP 2009, Berlin: Springer-Verlag , 2009, s. 92-102Konferansepaper (Fagfellevurdert)
    Abstract [en]

    To completely segment all individual wood fibres in volume images of fibrous materials presents a challenging problem but is important in understanding the micro mechanical properties of composite materials. This paper presents a filter that identifies and closes pores in wood fibre walls, simplifying the shape of the fibres. After this filter, a novel segmentation method based on graph cuts identifies individual fibres. The methods are validated on a realistic synthetic fibre data set and then applied on μCT images of wood fibre composites.

  • 749.
    Wernersson, Erik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Centrum för bildanalys. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datoriserad bildanalys.
    Luengo Hendriks, Cris L.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Centrum för bildanalys.
    Brun, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Centrum för bildanalys.
    Generating synthetic μCT images of wood fibre materials2009Inngår i: Proc. 6th International Symposium on Image and Signal Processing and Analysis: ISPA 2009, Piscataway, NJ: IEEE , 2009, s. 365-370Konferansepaper (Fagfellevurdert)
    Abstract [en]

    X-ray Computerized Tomography at micrometer resolution (μCT) is an important tool for understanding the properties of wood fibre materials such as paper, carton and wood fibre composites. While many image analysis methods have been developed for μCT images in wood science, the evaluation of these methods if often not thorough enough because of the lack of a dataset with ground truth. This paper describes the generation of synthetic μCT volumes of wood fibre materials. Fibres with a high degree of morphological variations are modeled and densely packed into a volume of the material. Using a simulation of the μCT image acquisition process, realistic synthetic images are obtained. This simulation uses noise characterized from a set of μCT images. The synthetic images have a known ground truth, and can therefore be used when evaluating image analysis methods.

  • 750. Wessels, C.B
    et al.
    Crafford, P.L
    du Toit, B
    Grahn, Thomas
    RISE, Innventia.
    Johansson, M
    Lundqvist, Sven-Olof
    RISE, Innventia.
    Säll, H
    Seifert, T
    Variation in physical and mechanical properties from three drought tolerant Eucalyptus species grown on the dry west coast of Southern Africa2016Inngår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, s. 1-13Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Southern Africa, and specifically its western parts is dominated by low rainfall areas, and it is expected that the rainfall in most of these parts will in future decrease further due to climate change. Woodlots of fast-growing, non-invasive tree species can provide the opportunity to produce wood and release the pressure on natural woodlands, while creating much needed income to inhabitants. Over the last two decades several trials of Eucalyptus species that could potentially withstand arid conditions were established on the South African west coast. The three most promising genotypes according to their volume growth were selected among 46 pure and hybrid species from two 20-year-old trials for further evaluation. These included 10 Eucalyptus grandis × Eucalyptus camaldulensis hybrid trees, 9 Eucalyptus gomphocephala trees, and 9 Eucalyptus cladocalyx trees for a total of 28 trees. The objective of the study reported here was to investigate the within-tree and between species variability of selected physical and processing properties determining the suitability of these three species for lumber production. The density, microfibril angle, spiral grain angle, MOE, MOR, radial and tangential shrinkage, twist, bow, splitting, and collapse were measured in a radial and longitudinal gradient. Valuable insights were gained which could provide decision support for planting, processing and further research on these species when grown in arid conditions. The E. grandis × camaldulensis hybrid was inferior in terms of most relevant properties to the other two species evaluated. The main shortcoming of both E. gomphocephala and E. cladocalyx was the high levels of twist in lumber.

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