lnu.sePublications
Change search
Refine search result
4567 301 - 343 of 343
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 301.
    Sterley, Magdalena
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Gustafsson, Per Johan
    Lund University.
    Shear Fracture Characterisation of Green Glued Polyurethane Wood Adhesive Bonds at Various Moisture and Gluing Conditions2012In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 7, no 2, p. 93-100Article in journal (Refereed)
    Abstract [en]

    The shear fracture properties of green-glued one-component polyurethane (PUR) wood adhesive bonds subjected to kiln drying were investigated. The local shear strength and fracture energy of the wood adhesive bonds were determined from experimentally recorded complete shear stress versus deformation curves of the bond line. A stable test set-up and small specimens that were anti-symmetrically loaded were used in order to get a uniform and pure state of shear stress. Different moisture contents (MCs) and pressing times were investigated. The fracture properties of conventionally dry-glued wood adhesive bonds and of solid wood were used as reference. The results show that the fracture energy of green-glued bonds with PUR adhesive is dependent on the MC of wood and on the pressing time. The same fracture energy and strength can be obtained by green gluing as by dry gluing, but there seems to exist a maximum MC of sapwood, in the range between 78% and 160%, and a minimum pressing time, in the range between 3 h and 48 h, for which it can be achieved. Both dry- and green-glued polyurethane adhesive bonds were more ductile than solid wood.

  • 302.
    Sterley, Magdalena
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Serrano, Erik
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Enquist, Bertil
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Flat wise green gluing of Norway spruce for structural application2009In: International Conference on Wood Adhesives 2009 / [ed] Charles Frihart, Madison: Forest Products Society, 2009, p. 325-334Conference paper (Refereed)
    Abstract [en]

    Unseasoned (green) Spruce timber planks with dimensions25 x 150 x 5400 mm3 were flat-wise glued with a one-componentPUR adhesive, forming laminated beams with 150 x 300 mm2 crosssection.After curing, each beam was divided in two halves and subsequentlydried. The final cross-section of the beams was thus 50 x 300mm2. The evaluation of the beams included bending stiffness andbending strength in 4-point bending and the mechanical properties ofthe adhesive bonds. The adhesive bonds were tested according toEuropean standards for glued-laminated timber (EN 392, EN 391) andaccording to ASTM D 905, but also with a special small-scale specimenfor testing the fracture properties of the adhesive bond in Mode I.The complete force vs. deformation curve, including both the ascendingand the descending parts could be obtained. The deformationswere measured with a contact-free technique, based on two camerasand white light. The equipment made it possible to register the strainin the bond line and in the adjacent wood with a high spatial resolution(0,2 mm). The strength of the bond line and the fracture energywas calculated. Results show that both the stiffness and the strength ofthe beams can comply with the requirements for glued-laminated timberclass L40. The adhesive bonds fulfill the requirements of glulam instandard EN 386. The tensile strength and fracture energy measuredwith the small specimens of green-glued bond lines is on the samelevel as of conventionally glued bond lines.

  • 303.
    Sterley, Magdalena
    et al.
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Serrano, Erik
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Enquist, Bertil
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Fracture characterisation of green glued-polyurethane adhesive bonds in Mode I2013In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 46, no 3, p. 421-434Article in journal (Refereed)
    Abstract [en]

    Unseasoned (green) spruce timber side boards of size 25 × 120 × 600 mm were flatwise-glued with a one-component PUR adhesive. Glued pairs of boards were then kiln-dried to 12 % moisture content. A special small-scale specimen for testing the fracture properties of the adhesive bond in Mode I was developed in order to evaluate the adhesive bond properties. The complete force versus deformation curve, including both the ascending and the descending parts, could be obtained with these small-scale specimens, enabling the strength and fracture energy of the bond line to be calculated. In addition, the fractured specimens were examined by scanning electron microscope. Results show that both the tensile strength and the fracture energy of the green glued PUR adhesive bonds were equal to those of the dry glued bonds. The methodology developed and used in the present study gives new possibilities for analysis of the mechanical behaviour of wood adhesive bonds, and particularly of their brittleness and its correlation with the type of fracture path. This is in sharp contrast to the use of standardised test methods (e.g. EN 302, ASTM D905) with specimens having relatively large glued areas. Using such types of specimens, it is not possible to obtain the complete force versus deformation response of the bond. In addition, when using such test methods, failure takes place in the wood or in the fibres near the bond, thus making it impossible to obtain detailed information about the bond line characteristics.

  • 304.
    Sterley, Magdalena
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Trey, Stacy
    SP Wood Technol.
    Lundevall, Åsa
    Swerea IVF.
    Olsson, Sara
    SP Wood Technol.
    Influence of cure conditions on the properties of a one-component moisture-cured polyurethane adhesive in the context of green gluing of wood2012In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 126, no S1, p. E296-E303Article in journal (Refereed)
    Abstract [en]

    A commercial one-component moisture-cured polyurethane-urea wood adhesive was investigated under different curing environments to simulate parameters during green gluing, that is, gluing of freshly sawn and undried timber. This process is an eco-efficient and waste eliminating process in which only the finished wood product properties have been tested; however, not the adhesive itself. Therefore, the effect of moisture and postcuring heat treatment on the adhesive properties such as cure, chemical, and physical characteristics, and adhesion to wood were studied. It was determined by rheometry that the water content was proportional to the time to gel point, with moisture content of 2.65.6 wt % water, resulting in a higher initial storage modulus of the adhesive. Additionally, it was found that the strength of the wet glued bonds was significantly higher after the heat treatment, corresponding to the increase in ordered bidentate groups (Fourier transform infrared spectroscopy), higher storage modulus (rheometry), and higher Tg (dynamic mechanical thermal analysis).

  • 305.
    Strand, Michael
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Lutic, Doina
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. University of Kalmar, Department of Technology. Bioenergiteknik.
    Sanati, Mehri
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. University of Kalmar, Department of Technology. Bioenergiteknik.
    Catalyst properties of oxide nanoparticles applied in gas sensors manufacturing2006In: 12th Nordic Symposium in Catalysis-May 28-30-Trondheim-Norway, 2006, p. 167-168Conference paper (Other academic)
  • 306.
    Svensson, Ingvar L
    et al.
    Jönköping University.
    Dugic, Izudin
    Jönköping University.
    Modelling of volumes in cast iron solidification to predict shrinkage and expansion defects1999In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 11, no 6, p. 489-494Article in journal (Refereed)
  • 307.
    Svensson, Niklas
    et al.
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Holmberg, Martin
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Offshore cable protection2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The market for renewable energy and an international power grid is constantly growing. This project has focused on the installation and protection methods for offshore power cables. Long distance cables over e.g. oceans and smaller distances within offshore wind farms.

    The focus is on three different materials for the protection task; concrete, cast iron and plastics. These materials have been evaluated in aspect to strength, life-length, reliability and environmental impact.

    Snapp products of Sweden AB have developed a cable protective pipe of polypropylene for offshore usage. This product and its opportunities are thoroughly investigated.

    Download full text (pdf)
    offshore cable protection - degree project
  • 308.
    Svidró, Peter
    et al.
    Jönköping University.
    Elmquist, Lennart
    SinterCast AB.
    Dugic, Izudin
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Diószegi, Attila
    Jönköping University.
    Characterization of primary dendrite morphology in complex shaped lamellar cast iron castings2014In: The 10th International Symposium on the Science and Processing of Cast Iron, SPCI10, November, 2014, Mar del Plata, Argentina, 2014, p. 1-7Conference paper (Refereed)
    Abstract [en]

    Shrinkage porosity and metal expansion penetration are two fundamental defects appearing during the production of complex shaped lamellar cast iron components. Simplified test models simulating the thermal and geometrical conditions existing in complex shaped castings have been successfully used to provoke shrinkage porosity and metal expansion penetration. A stereological investigation of the primary dendrite morphology indicates a maximum intra-dendritic space in connection with the casting surface where the porosity and the penetration defects appear. Away from the defect formation area the intra-dendritic space decreases. Comparison of the simulated local solidification times and measured intra-dendritic space indicates a strong relation which can be explained by the dynamic ripening process. The slow local solidification time situated at the boundary between the casting surface and its surrounding is explained to be the reason for the formation of an austenite morphology which can promote mass flow between dendrites, thereby provoking shrinkage porosity or metal expansion penetration.

  • 309.
    Svidró, Péter
    et al.
    Jönköping University.
    Elmquist, Lennart
    Jönköping University.
    Dugic, Izudin
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Diószegi, Attila
    Jönköping University.
    Investigation of cooling rate dependent dendrite morphology in hypoeutectic lamellar cast iron2013Report (Other academic)
    Abstract [en]

    Shrinkage porosity and metal expansion penetration are two fundamental defects appearing at production ofcomplex shaped lamellar cast iron components. In previous work it has been shown that both shrinkageporosity and metal expansion penetration are related to the primary austenite dendrite network and itsformation mechanisms. The purpose of the present work is to study the morphology of primary austenite intest casting with a high tendency to form shrinkage porosity and metal expansion penetration. Simplified testmodels simulating the thermal and geometrical conditions similar to the conditions existing in complex shapedcasting have been successfully used to provoke shrinkage porosity and metal expansion penetration.Stereological investigation of the primary dendrite morphology indicates a maximum interdendritic space inconnection to the casting surface where the porosity and the penetration defect appear. Away from the defectformation area the interdendritic space decreases. Furthermore the local solidification times of the investigatedsamples were calculated in a 3D simulation software. Comparison of the simulated local solidification timesand measured interdendritic space indicates a strong relation of the same shape as it is known from theliterature when dynamic coarsening mechanism is characterized. The main outcome of the present paper is theobserved gradient of increasing interdendritic space from sections with high local solidification to sectionswith low solidification time. The mechanism of increasing the interdendritic phase can be explained by thedynamic ripening process. The unfortunate thermal conditions with the slowest local solidification timesituated in the border between the casting surface and its surrounding are considered the reason to form anaustenite morphology which can promote the mass flow between dendrite provoking shrinkage porosity ormetal expansion penetration.

    Download full text (pdf)
    FULLTEXT01
  • 310.
    Svidró, Péter
    et al.
    Jönköping University.
    Elmquist, Lennart
    Jönköping University.
    Dugic, Izudin
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Diószegi, Attila
    Jönköping University.
    Investigation of cooling rate dependent dendrite morphology inhypoeutectic lamellar cast iron2013Report (Other academic)
    Abstract [en]

    Shrinkage porosity and metal expansion penetration are two fundamental defects appearing at production ofcomplex shaped lamellar cast iron components. In previous work it has been shown that both shrinkageporosity and metal expansion penetration are related to the primary austenite dendrite network and itsformation mechanisms. The purpose of the present work is to study the morphology of primary austenite intest casting with a high tendency to form shrinkage porosity and metal expansion penetration. Simplified testmodels simulating the thermal and geometrical conditions similar to the conditions existing in complex shapedcasting have been successfully used to provoke shrinkage porosity and metal expansion penetration.Stereological investigation of the primary dendrite morphology indicates a maximum interdendritic space inconnection to the casting surface where the porosity and the penetration defect appear. Away from the defectformation area the interdendritic space decreases. Furthermore the local solidification times of the investigatedsamples were calculated in a 3D simulation software. Comparison of the simulated local solidification timesand measured interdendritic space indicates a strong relation of the same shape as it is known from theliterature when dynamic coarsening mechanism is characterized. The main outcome of the present paper is theobserved gradient of increasing interdendritic space from sections with high local solidification to sectionswith low solidification time. The mechanism of increasing the interdendritic phase can be explained by thedynamic ripening process. The unfortunate thermal conditions with the slowest local solidification timesituated in the border between the casting surface and its surrounding are considered the reason to form anaustenite morphology which can promote the mass flow between dendrite provoking shrinkage porosity ormetal expansion penetration.

    Download full text (pdf)
    FULLTEXT01
  • 311.
    Säll, Harald
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Skog och trä.
    Källsner, Bo
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Skog och trä.
    Olsson, Anders
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Byggteknik.
    Bending strength and stiffness of aspen sawn timber2007In: Quality Control for Wood and Wood Products, COST, Warsaw , 2007, p. 6-Conference paper (Refereed)
    Abstract [en]

    In order to investigate the possibility of using sawn timber of European aspen (Populus tremula L.) as a structural

    material, 150 pieces of the dimension 45 x 120 mm2 were selected from a sawmill in the south of Sweden. The material was

    visually strength graded using the Nordic standard INSTA 142 and the British standard BS 4978-1996, respectively.

    The timber pieces were also subjected to flat-wise bending in a Cook-Bolinder Ò strength grading machine. Finally all

    specimens were tested in edge-wise bending according to the European testing standard EN 408. Global and local moduli

    of elasticity as well as bending strength were determined.

    The results indicate that the visual grading rules, intended for use on Norway spruce and Scots pine, seem to work fairly

    well on European aspen. However, grading in a flat-wise bending machine like the Cook-Bolinder seems to give a lower

    correlation between stiffness and strength for aspen timber than generally found for coniferous. Further, the correlation

    between density and bending strength was found to be very low for the aspen timber tested. It was also noticed that

    the aspen timber has a slightly higher bending strength and modulus of elasticity than is the case for normal qualities

    of Norway spruce.

    The study indicates that sawn timber of European aspen grown in southern Sweden can be visually graded and used

    as structural material.

  • 312.
    Tabikh, Mohamad
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Khattab, Ammar
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Scheduled maintenance policy for minimum cost: a case study2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report evaluate the maintenance policies that been applied within specific industrial company, Taken into considerations all corrective and preventive maintenance costs ,in addition to optimise best preventive maintenance schedule for minimum cost.

    Dynamate Intralog AB was the surveyed company that been encountered high maintenance cost compatible with less productivity, therefore obtaining maintenance schedule policy for minimum cost was the best solution for their problem, then by calculating their corrective and preventive maintenance cost the optimum time was acquired. Finally, the maintenance schedule approve that organized maintenance based on optimum time enhance the productivity and minimize the company maintenance cost.

    Download full text (pdf)
    fulltext
  • 313.
    Taghiyari, Hamid Reza
    et al.
    Shahid Rajaee Teacher Training University, Iran.
    Elyasi, Abdollah
    University of Tehran, Iran.
    Doost-Hoseini, Kazem
    University of Tehran, Iran.
    Hosseinpourpia, Reza
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology. Georg August University Gottingen, Germany.
    Correlation between gas and liquid permeability with noise reduction coefficient in insulation boards made from sugar cane bagasse2017In: Bulgarian Journal of Agricultural Science, ISSN 1310-0351, Vol. 23, no 3, p. 674-681Article in journal (Refereed)
    Abstract [en]

    Specific gas and liquid permeability, as well as noise reduction coefficients, in insulating boards made of sugar-cane bagasse were studied here. Urea-formaldehyde (UF) and melamine-urea-formaldehyde (MUF) were used to produce homogeneous as well as three-layered insulating boards with three densities of 0.3, 0.4, and 0.5 g/cm3. The obtained results indicated that MUF slightly decreased gas and liquid permeability, but it did not significantly affect the noise reduction coefficients. Gas and liquid permeability were considerably affected by the density of the boards, due to the compression between the bagasse particles and less spaces and voids to let the fluids to pass through. However, noise reduction coefficients were significantly affected both by the density, as well as the board-type. More compression between the particles and the consequent less space between the bagasse particles entangled the waves; further more, the sudden change between the layers in the three-layered boards formed a barrier towards transmission of waves.

  • 314.
    Taghiyari, Hamid Reza
    et al.
    Shahid Rajaee Teacher Training University, Iran.
    Tajvidi, Mehdi
    University of Maine, USA.
    Taghiyari, Reyhaneh
    Payame Noor University, Iran.
    Mantanis, George
    University of Thessaly, Greece.
    Esmailpour, Ayoub
    Shahid Rajaee Teacher Training University, Iran.
    Hosseinpourpia, Reza
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Nanotechnology for wood quality improvement and protection2020In: Nanomaterials for Agriculture and Forestry Applications: Micro and Nano Technologies / [ed] Azamal Husen and Mohammad Jawaid, Elsevier, 2020, p. 469-489Chapter in book (Refereed)
    Abstract [en]

    Wood is a natural renewable material with unique properties helping mankind to build and develop its communities since the genesis of human on the Earth. Moreover, wood/cellulosic composites provide the opportunity to utilize low-density wood species and agricultural materials that are basically not suitable for structural applications. Although wood is considered irreplaceable, it has some disadvantages narrowing its applications and limiting its service life. These disadvantages mainly include its susceptibility to water and water vapor, biological deteriorating fungi, insects, termites, and marine borers. The present chapter tries to summarize some main areas in which nanotechnology is being used to improve wood and lignocellulosic-based composite panels. Moreover, some new applications and capabilities of this precious natural material are also brought into perspective, areas such as transparent wood, self-cleaning coatings, and smart windows. Though some areas have been thoroughly studied, much potential still exists for further studies and commercialization.

  • 315.
    Trischler, Johann
    et al.
    Luleå University of Technology, Sweden.
    Sandberg, Dick
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology. Luleå University of Technology, Sweden.
    Dorn, Michael
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Vital gluten for particleboard production: effect of wood-particle moisture on board properties2018In: Forest products journal, ISSN 0015-7473, Vol. 68, no 2, p. 127-131Article in journal (Refereed)
    Abstract [en]

    The growing environmental awareness is leading to an increased interest in the use of bio-based adhesives and proteins such as vital gluten. The purpose of this study was to investigate the influence of the wood-particle moisture content, water application and press time on the internal bond strength, thickness expansion and thickness swelling of particleboards glued with vital gluten. Green and dried wood particles with similar moisture contents were achieved through drying or water addition and were blended with vital gluten powder and pressed for 1 to 3 minutes. The results show that not only the pressing time and moisture content, but also the way of achieving the moisture content has a strong impact on the performance of the boards. At comparable moisture content, never-dried (green) particles with high moisture content in combination with a dry adhesive application produced boards which performed better than boards made of dry particles with water addition to simulate liquid adhesive application.

  • 316. Valai, A
    et al.
    Birbilis, D
    Karageorgos, A
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Estimation of properties of recovered paper used for the production of corrugated board2015Conference paper (Refereed)
    Abstract [en]

    The objective of this paper was the estimation of corrugated board mechanical properties based on the fiber characteristics from recovered paper and some physical properties (mainly grammage and thickness). Two kind of papers (liners and flutings) used for corrugated board production in Greece were examined. After the experimental determination of a plenty of variables, linear regressions were developed among those variables. Regressions led to some linear models with significant correlations between mechanical properties and fiber characteristics or physical properties (grammage and thickness). For the recycled paper of the liners category, significant correlations were observed considering tensile strength, tearing strength and zero span strength. For the recycled paper of the flutings category, significant correlations were observed considering compression strength and tearing strength

  • 317.
    Voulgaridis, Elias
    et al.
    Aristotle University, Greece.
    Passialis, Costas
    Aristotle University, Greece.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    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 ]2017In: 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, p. 315-323Conference paper (Refereed)
    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.

  • 318. 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 Study2015In: 32nd Danubia-Adria-Symposium (DAS 32), Zilina, Slovakia, 2015, p. 162-163Conference paper (Other academic)
  • 319.
    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 Investigations2012In: COST Action FP0802 - Experimental and Computational Micro-Characterization Techniques in Wood Mechanics, Edinburgh, UK, 2012, p. 72-73Conference paper (Other academic)
    Download full text (pdf)
    fulltext
  • 320.
    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 approach2012In: Trees, ISSN 0931-1890, E-ISSN 1432-2285, Vol. 27, no 1, p. 321-336Article in journal (Refereed)
    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.

  • 321. 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 Validation2012Conference paper (Other academic)
  • 322.
    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 Wood2014In: 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, 2014Conference paper (Other academic)
    Download (pdf)
    sammanfattning
  • 323. 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 Methods2013Conference paper (Other academic)
  • 324.
    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 protocol2014In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 49, no 1, p. 94-102Article in journal (Refereed)
    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.

  • 325. 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 Stiffness2012In: 29th DANUBIA-ADRIA SYMPOSIUM on Advances in Experimental Mechanics, September 26-29, Belgrade, Serbia, Belgrade, Serbia, 2012, p. 8-9Conference paper (Other academic)
  • 326.
    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 Walls2015Conference paper (Other academic)
    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.

  • 327.
    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 modeling2014In: International Biodeterioration & Biodegradation, ISSN 0964-8305, E-ISSN 1879-0208, Vol. 93, p. 223-234Article in journal (Refereed)
    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.

  • 328.
    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 Softwood2011In: COST Action FP0802 - Experimental and Computational Micro-Characterization Techniques in Wood Mechanics, Helsinki, Finland, 2011, p. 61-62Conference paper (Other academic)
    Download full text (pdf)
    fulltext
  • 329.
    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 softwood2015In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 69, no 4, p. 471-482Article in journal (Refereed)
    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.

  • 330.
    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 Study2015In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 10, no 3Article in journal (Refereed)
    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.

  • 331. 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 Study2014In: 16th International Conference on Experimental Mechanics (ICEM16), July 7-11, 2014, Cambridge, Cambridge, UK, 2014Conference paper (Other academic)
    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).

  • 332. 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 Study2014In: 31st Danubia-Adria Symposium on Advances in Experimental Mechanics, September 24-27, 2014, Kempten, 2014, p. 151-152Conference paper (Other academic)
  • 333. 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 Level2012In: 7th International Plant Biomechanics Conference, August 20-24, 2012, Clermont-Ferrand, France, Clermont-Ferrand, France, 2012Conference paper (Other academic)
  • 334. Wikete, Christoph
    et al.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Jäger, Andreas
    Hofstetter, Karin
    Eberhardsteiner, Josef
    Mechanical Properties and Microstructural Characteristics of Hardwood2010In: 27th Danubia-Adria Symposium on Advances in Experimental Mechanics : September 22nd - 25th, 2010, Wrocław University of Technology, Wrocław, Poland / [ed] Romuald Be̜dziński, Wroclaw, Poland: Wrocław University of Technology , 2010, p. 237-238Conference paper (Other academic)
  • 335.
    Wojcik, Natalia A.
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. Gdansk Univ Technol, Poland.
    Jonson, Bo
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Möncke, Doris
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. Natl Hellen Res Fdn, Greece.
    Polies, D.
    Natl Hellen Res Fdn, Greece.
    Kamitsos, E. I.
    Natl Hellen Res Fdn, Greec.
    Ghassemali, E.
    Jönköping University.
    Seifeddine, S.
    Jönköping University.
    Eriksson, M.
    Stockholm University.
    Ali, Sharafat
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Influence of synthesis conditions on glass formation, structure and thermal properties in the Na2O-CaO-P2O5 system doped with Si3N4 and Mg2018In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 494, p. 66-77Article in journal (Refereed)
    Abstract [en]

    Oxynitride phosphate glasses and glass-ceramics were prepared using new synthesis routes for phosphate glasses. Materials were melted from pre-prepared glass samples in the system Na-Ca-P-0 with addition of Mg and/or Si3N4 powders under different preparation conditions. The melting process was conducted at 1000-1500 degrees C either under air or nitrogen atmosphere to obtain materials with different nitrogen content. Their topography and structure were characterized by Confocal Microscopy, Scanning Electron Microscopy, X-ray powder diffraction and Raman and infrared spectroscopy techniques, while their chemical compositions were examined by Energy Dispersive X-ray spectroscopy (EDS). All materials prepared under nitrogen atmosphere were found to contain a relative low quantity of nitrogen and high amount of Nb leached from the crucible. The reaction with the Nb crucible was not previously observed for silicon-based oxynitride glasses. The synthesized materials form two groups: glasses and glass-ceramics. The first ones, were prepared under air and nitrogen atmospheres at temperatures up to 1400 degrees C, and were found to be amorphous and homogeneous. Raman and infrared spectroscopy measurements confirm the presence of amorphous phosphates in the synthesized materials. The samples of the second group were prepared at temperatures above 1400 degrees C and were found to be translucent and partially crystallized. They contain nanocrystallites of calcium and sodium phosphates including hydroxyapatite (HAp). The thermal properties of samples were studied by Differential Scanning Calorimetry (DSC). The obtained glass transition temperatures range from about 360 degrees C to 640 degrees C and exhibit high values for glass-ceramic materials. Stability is improved in the studied glass-ceramics because of the increased degree of network polymerization of the remaining glassy matrix. The approximate fragility index decreases two times for oxynitride materials compared to the primary glass. The synthesized new materials may be competitive to well-known bioactive phosphate glasses thanks to their improved stability by Mg, Si, N and Nb doping.

  • 336.
    Wojcik, Natalia A.
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. Gdansk Univ Technol, Poland.
    Kupracz, P.
    Gdansk Univ Technol, Poland.
    Barczynski, R. J.
    Gdansk Univ Technol, Poland.
    Nonlinear electrical properties of glass-ceramics nanocomposites containing ferroelectric nanocrystallites of Bi2VO5.52018In: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 317, p. 7-14Article in journal (Refereed)
    Abstract [en]

    Nonlinear A.C. impedance measurements were conducted in the 50BiV-50SrBAlO nanocomposite as a function of frequency, temperature and A.C. voltage. This material is ferroelectric below temperature of 730 K, and above 730 K is a good ion-conductor. For this nanocomposite a low A.C. voltage of 1 V-rms, is enough to observe high nonlinearities. The origin of these nonlinear effects depends on the temperature and frequency. In the high temperature and low frequency region, the nonlinearities are due to interfacial processes. In the low temperatures and higher frequencies, the nonlinearities may be also correlated with ion-transport processes: hopping and blocking in glass matrix and phase boundaries. The ferroelectric properties of the Bi2VO5.5 nanocrystallites are also possible origin of nonlinear effects. However, their contribution into nonlinearities is weaker than from the other observed processes. It is shown that a decrease of the Bi2VO5.5 crystallites size from micro- to nanometers and introduction of additional structural disorder into material significantly decrease the real part of the third order electric susceptibility coefficient but does not influence the ratio of the third harmonic to the base conductivity. It is suggested that the ferroelectric nanoregions are single-domain and the nonlinearities derived from domain walls probably are not observed.

  • 337.
    Wu, Min
    et al.
    Technical University of Denmark, Denmark;COWI AS, Denmark.
    Fridh, Katja
    Lund University.
    Johannesson, Björn
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Geiker, Mette
    Norwegian University of Science and Technology, Norway.
    Impact of sample crushing on porosity characterization of hardened cement pastes by low temperature calorimetry: Comparison of powder and cylinder samples2018In: Thermochimica Acta, ISSN 0040-6031, E-ISSN 1872-762X, Vol. 665, p. 11-19Article in journal (Refereed)
    Abstract [en]

    Theimpact of sample crushing on the detected porosity of hardened cement pastes bylow temperature calorimetry (LTC) was studied using powder and cylindersamples. Two types of cements, CEM I and CEM III were used to prepare thepastes. A model porous material, MCM-41, was also used in order to investigatesome aspects of the measurement and the evaluation approach. The powder andcylinder samples of the cement pastes were compared in terms of the calculatedice content curves, total pore volumes and pore size distribution curves. For thetwo studied cement pastes, the calculated ice content curves of freezing of thepowder sample differed from that of the cylinder samples, especially for thepaste CEM III. The results indicate that sample crushing changed the poreconnectivity as compared to non-crushed samples. One important differencebetween the powder sample and the cylinder samples of the paste CEM III wasthat the determined maximum ice content in the powder sample was much higherthan that in the cylinder samples, the relatively difference being about 40–50%.However, this kind of marked difference was not found in the paste CEM I. Theobserved difference between the calculated pore volume of the powder and thecylinder samples of the paste CEM III is possibly due to some of the “isolated”pores which, presumably, cannot be fully filled with water in the preparationof the cylinder samples. However, sample crushing makes it possible to saturatethe pores to a greater extent if the crushing contributes to open up the“isolated” pores. Consequently, more pores are detected in the powder samples.The argument that the “isolated” pores have a tendency to be opened up by thecrushing process is supported by results using gravimetric measurements and“dynamic (water) vapor sorption” measurements on powder samples.

  • 338.
    Wójcik, Natalia A.
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. Gdańsk University of Technology, Poland.
    Ali, Sharafat
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Möncke, Doris
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. Alfred University, USA;National Hellenic Research Foundation, Greece.
    Kamitsos, Efstratios
    National Hellenic Research Foundation, Greece.
    Segawa, Hiroyo
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. National Institute for Materials Science, Japan.
    Eriksson, Mirva
    Stockholm University, Sweden.
    Jonson, Bo
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    The influence of Be addition on the structure and thermal properties of alkali-silicate glasses2019In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 521, article id 119532Article in journal (Refereed)
    Abstract [en]

    Be-Na-(Li)-Si oxide glasses containing up to 15 mol% of BeO were prepared. Their structure was characterized by X-ray powder diffraction and Raman as well as infrared spectroscopic techniques, while their chemical compositions were examined by Inductively Coupled Plasma Optical Emission Spectrometry. All materials were found to be amorphous and contain Al contaminations from minor dissolution of the alumina crucibles. The results of Raman and IR spectroscopies showed that BeO addition to Na-(Li)-Si glass systems resulted in the formation of [BeO4/2]2− tetrahedra which are inserted into the silicate glass network, demonstrating the intermediate glass-forming role of BeO. In parallel, the effective destruction of Si-O-Si bridges was observed by vibrational spectroscopy. The glass transition temperature was studied by Differential Thermal Analysis and found to range from about 431 °C to 551 °C. A significant increase in Tg by 70 °C was found as SiO2 was substituted by up to 15 mol% BeO.

  • 339.
    Wójcik, Natalia A.
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. Gdansk Univ Technol, Poland.
    Jonson, Bo
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Barczynski, R. J.
    Gdansk Univ Technol, Poland.
    Kupracz, P.
    Gdansk Univ Technol, Poland.
    Woncke, D.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. Natl Hellen Res Fdn, Greece.
    Ali, Sharafat
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Electrical properties of Na2O-CaO-P2O5 glasses doped with SiO2 and Si3N42018In: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 325, p. 157-162Article in journal (Refereed)
    Abstract [en]

    Sodium-calcium-phosphate glasses doped with SiO2 or Si3N4 having similar sodium ion concentrations were prepared by melt quenching. The conductivity was measured by impedance spectroscopy under nitrogen atmosphere in a wide frequency range (10 mHz-1 MHz) and wide temperature range (153-473 K). At 36.6 degrees C, DC conductivities of all glasses vary between 1.1 *10(-12) and 8.9 * 10(-12) S cm(-1) and have similar activation energies (between 0.87 and 0.91 eV), which are characteristic for an ionic conduction mechanism. The analysis of AC conductivities showed that the spectra are governed by one dynamic process - hopping of the mobile charge carriers - which may be described i.e., by the 'concept of mismatch and relaxation' or by the 'random barrier' model. The obtained results confirmed a higher influence of nitrogen incorporation on the various glass conductivity parameters than shown for silicon doping alone. However, the influence of fundamental structural changes on the glass conductivity is less relevant as is the overall sodium ion concentration, which remains the decisive factor for a high ion conduction.

  • 340. Wójcik, Natalia A.
    et al.
    Jonson, Bo
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Möncke, Doris
    Alfred University, NY, USA.
    Barczyński, Ryszard
    Kupracz, Piotr
    Kamitsos, Efstratios
    Ghassemali, Ehsan
    Seifeddine, Salem
    Eriksson, Mirva
    Ali, Sharafat
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Influence of synthesis conditions on glass formation, structure, thermal and electrical properties in the Na2O-CaO-P2O5 system doped with Si3N4 and Mg2018Conference paper (Refereed)
  • 341.
    Wójcik, Natalia A.
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. Gdańsk University of Technology, Poland.
    Jonson, Bo
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Möncke, Doris
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. National Hellenic Research Foundation, Greece;Alfred University, USA.
    Kamitsos, Efstratios
    National Hellenic Research Foundation, Greece.
    Segawa, Hiroyo
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. National Institute for Materials Science, Japan.
    Karczewski, Jakub
    Gdańsk University of Technology, Poland.
    Ali, Sharafat
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    The effect of nitrogen on the structure and thermal properties of beryllium-containing Na-(Li)-Si-O-N glasses2019In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 522, p. 1-8, article id 119585Article in journal (Refereed)
    Abstract [en]

    Two oxynitride glass series with the composition of 35Na2O-5BeO-(60-x)SiO2-xSi3N4 and 9Li2O- 27Na2O-5BeO-(59-x)SiO2-xSi3N4, were prepared. The glasses' topography and structure were studied by Scanning Electron Microscopy and Raman spectroscopy. The composition was analyzed by Inductively Coupled Plasma Optical Emission Spectrometer, SEM-EDS and nitrogen and oxygen elemental analyzer. Na-(Li)-Be-silicate glasses were found to contain up to approximately 3.4 (or 5.2 for EDS measurements) at.% of N, respectively. The samples were homogenous in their topography and compositions of their cross-sections.

    The presence of three-fold coordinated nitrogen atoms in Na-Be-Si-O-N glasses results in higher degree of polymerization as was observed by Raman spectroscopy. The spectrum of analogous glasses with lithium did not show a significant decrease in Q2 units but exhibit the presence of Q4 units which also indicates a polymerization of the network. The incorporation of nitrogen in these glasses leads to the increase of the glass transition temperature and thermal stability.

  • 342.
    Wójcik, Natalia A.
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. Gdańsk University of Technology, Poland.
    Kupracz, P
    Gdańsk University of Technology, Poland;Polish Academy of Science, Poland.
    Barczyński, Ryszard. J
    Gdańsk University of Technology, Poland.
    Jonson, Bo
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Ali, Sharafat
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Ion conduction in beryllium-alumino-silicate glasses doped with sodium or sodium and lithium ions2019In: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 341, p. 1-7, article id 115055Article in journal (Refereed)
    Abstract [en]

    Electrical properties of beryllium-alumino-silicate glasses containing sodium ions or sodium and lithium ions were studied with impedance spectroscopy technique over a frequency range from 10 mHz to 1 MHz and at temperature range from 213 to 473 K. The frequency- and temperature-dependent conductivity spectra of individual single alkali glasses were superimposed by means of the Summerfield scaling. Mixed-alkali glasses do not overlap into a single master curve. Glasses doped with sodium ions exhibit significantly higher values of D.C. conductivity and lower activation energy (~0.63 eV) than glasses doped with both sodium and lithium ions (~0.95 eV). The observed mixed-alkali effect can be described by the dynamic structure model (DSM). The conductivity pre-exponential factors and activation energy follow the Meyer-Neldel rule in both glass series. It was observed that the replacement of SiO2 by BeO in single cation glasses resulted in decrease in activation energy and pre-exponential factor σ0. In mixed cations glasses similar effect found for D.C. conduction process parameters was assigned to influence of both oxides BeO and Al2O3.

  • 343.
    Zehnder, Christoffer
    et al.
    Rhein Westfal TH Aachen, Germany.
    Peltzer, Jan-Niklas
    Rhein Westfal TH Aachen, Germany.
    Gibson, James S. K. -L.
    Rhein Westfal TH Aachen, Germany.
    Möncke, Doris
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. Natl Hellen Res Fdn, Greece.
    Korte-Kerzel, Sandra
    Rhein Westfal TH Aachen, Germany.
    Non-Newtonian Flow to the Theoretical Strength of Glasses via Impact Nanoindentation at Room Temperature2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 17618Article in journal (Refereed)
    Abstract [en]

    In many daily applications glasses are indispensable and novel applications demanding improved strength and crack resistance are appearing continuously. Up to now, the fundamental mechanical processes in glasses subjected to high strain rates at room temperature are largely unknown and thus guidelines for one of the major failure conditions of glass components are non-existent. Here, we elucidate this important regime for the first time using glasses ranging from a dense metallic glass to open fused silica by impact as well as quasi-static nanoindentation. We show that towards high strain rates, shear deformation becomes the dominant mechanism in all glasses accompanied by Non-Newtonian behaviour evident in a drop of viscosity with increasing rate covering eight orders of magnitude. All glasses converge to the same limit stress determined by the theoretical hardness, thus giving the first experimental and quantitative evidence that Non-Newtonian shear flow occurs at the theoretical strength at room temperature.

4567 301 - 343 of 343
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf