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  • 201.
    Hameed, Mahmood
    et al.
    Damascus University, Syria.
    Al-Douhji, Ziad
    The Possibility of Manufacturing Medium Density Fiber board (MDF) from Cotton Seeds hulls as a Waste by-Product of Cotton Oil and Determination of its mechanical Properties2013Ingår i: Minia Journal of Agricultural Research and Development, ISSN 1110-0257, Vol. 33, nr 1, s. 243-260Artikel i tidskrift (Refereegranskat)
    Abstract [en]

     This research has demonstrated for the first time the possibility of manufacturing models of Medium Density Fiber board (MDF)   from Cotton Seeds hulls as a Waste by-Product of Cotton with good mechanical Specifications comply with European specifications EN (DIN1999). A steady increase in the rates of resistance of models wood panels manufactured Medium Density Fiber board (MDF) of cotton seeds hulls with Static Binding Strength of the increasing of Proportion of each the glue used, harder and formaldehyde scavenger used. All models wood panels manufactured Medium Density Fiber board (MDF) Seeds hulls, which glued with 14% characterized  with bad mechanical specification dont Comply with European standards for technical quality EN (DIN1999) and must be excluded.  All models wood panels manufactured Medium Density Fiber board (MDF) of Seeds hulls, which glued with 16% and 18% characterized with good mechanical Specifications Comply with European standards specifications, while the models glued with 18% characterized with soperior mechanical specifications for high technical quality, making it very good for the manufacture of furniture and coating halls. 

  • 202.
    Hameed, Mahmood
    et al.
    Damascus University, Syria.
    Al-Douhji, Ziad
    The Possibility of Manufacturing Medium Density Fiber board (MDF) from Cotton Seeds hulls as a Waste by-Product of Cotton Oil and Determination of its physical Properties2013Ingår i: Minia Journal of Agricultural Research and Development, ISSN 1110-0257, Vol. 33, nr 1, s. 219-242Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This research has demonstrated for the first time the possibility of manufacturing models of Medium Density Fiber board (MDF)   from Cotton Seeds hulls as a Waste by-Product of Cotton with good physical Specifications comply with European specifications EN (DIN1999).  Decrease in the average ability of models wood panels manufactured Medium Density Fiber board (MDF) of Seeds hulls to water absorption and the Cross-Swilling after 24h with the increasing Proportion of each the glue used, harder and formaldehyde scavenger used.  All models wood panels manufactured Medium Density Fiber board (MDF) Seeds hulls, which glued with 14% characterized  with bad physical specification dont Comply with European standards for technical quality EN (DIN1999) and must be excluded.  All models wood panels manufactured Medium Density Fiber board (MDF) of Seeds hulls, which glued with 16% and 18% characterized with good physical Specifications Comply with European standards specifications, while the models glued with 18% characterized with soperior physical specifications for high technical quality, making it very good for the manufacture of furniture and coating halls. 

  • 203.
    Hameed, Mahmood
    et al.
    Damascus University, Syria.
    Ayoub, Monier
    Aboud, Nesreen
    Study of Mechanical properties of River red gum Eucalyptus camaldulensis Dehn in Damascus-Daraa Road.2012Ingår i: Minia Journal of Agricultural Research and Development., ISSN 1110-0257, Vol. 32, nr 1, s. 37-64Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The River red gum (Eucalyptus camaldulensis Dehn. ) is found in a lot of places in Syria, and the trees in Damascus- Daraa Road are in  good height, diameter and growth, so that we aimed to study some of the mechanical properties of its wood related to the most important modern uses of this wood in industry.

    The study was done over Three trees, and three trunk masses of wood about 70 cm were taken from each tree from the beginning, the breast and the middle of the tree .

    The results show that the wood of Rever red gum has the following mechanical properties:

    -     The compression strength parallel to grain is medium (39.6 N/mm2), therefore, it is good in industries uses.

    -     The bending factor is weak (1.44) , and its coherence is medium  (2.27).

    -          The risistance of tensile strength was 40 N/mm2 .

    -          Hardness (Janka) was 38.3 N/mm2.

    So that we find out that the wood of River red gum is good and could be considered as a good wood with various uses and this spice is considered one of the promosing trees in our country for afforestration in zones like the stydy zones.

    As for the variance, ther are significant effects of tacking masses from tree on the physical and mechanical properties of the wood.

  • 204.
    Hameed, Mahmood
    et al.
    Damascus University, Syria.
    Ayoub, Monier
    Aboud, Nesreen
    Study of Physical properties of River red gum Eucalyptus camaldulensis Dehn.  in Damascus-Daraa Road.2012Ingår i: Minia Journal of Agricultural Research and Development., ISSN 1110-0257, Vol. 32, nr 1, s. 17-36Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The trees of River Red Gum in Damascus- Daraa Road are in a good height, diameter and growth, so that we aimed to study some of the physical properties of its wood related to the most important modern uses of this wood in industry.

    The study was done over Three trees, and three trunk masses of wood about 70 cm were taken from each tree from the beginning, the breast and the middle height of the tree.

    The results show that the wood of Rever red gum has the following physical properties:

    • It is hard, in which the density was 0.63 g/cm3, and this means that it is resistant to mechanical stress and sutable for using in building and engineering constructions.
    • The shrinkage is high.
    • As for the variance, there are significant effects of tacking masses from tree on the physical properties of the wood.
  • 205.
    Hameed, Mahmood
    et al.
    University of Göttingen, Germany.
    Behn, Claus
    University of Göttingen, Germany.
    Roffael, Edmone
    University of Göttingen, Germany.
    Dix, Brigitta
    Wilhelm-Klauditz-Institut (WKI), Germany.
    Benetzbarkeit von Recyclingspänen und ,,frischen“ Holzspänen mit verschiedenen Bindemitteln: [Wettability of fresh chips (chips obtained directly from wood) and chips obtained by mechanical disintegration (M-chips) and  thermohydrolytical degredation (T-chips) of particleboards with UF-, PF-resins and binders based on PMDI (polymers of diphenylmethan diisocyanates)]2005Ingår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 63, nr 5, s. 394-395Artikel i tidskrift (Refereegranskat)
    Abstract [de]

    Nach allen Messzeiten zeigten die „frischen“ Holzspäne eine bessere Benetzung mit UF-Harz, PF-Harz und PMDI-Klebstoff als die Recyclingspäne. Besonders durch mechanische Zerklei- nerung gewonnene Recyclingspäne weisen eine geringere Benet- zung auf als die „frischen“ Holzspäne. Dies ist womöglich auf das den Recyclingspänen anhaftende Binde- und Hydrophopie- rungsmittel zurückzuführen. Die bessere  Benetzung der durch thermohydrolytischen Aufschluss gewonnenen Späne ist möglicherweise darauf zurückzuführen, dass während des Aufschlus- ses Teile des Bindemittels chemisch abgebaut und wasserlöslich werden. Die Benetzung der Recyclingspäne mit PMDI ist auffallend besser als mit UF- und PF-Harz. Dies ist unabhängig davon, ob die zu benetzenden Späne durch mechanische Zerkleinerung oder durch thermohydrolytischen Aufschluss gewonnen wurden.

  • 206.
    Hameed, Mahmood
    et al.
    Göttingen University, Germany.
    Behn, Claus
    Göttingen University, Germany.
    Roffael, Edmone
    Göttingen University, Germany.
    Dix, Brigitta
    Wilhelm-Klauditz-Institut (WKI), Germany.
    Wasserrückhaltevermögen von Recyclingspänen und von direkt aus Holz gewonnenen Spänen: [The water retention value of dried wood particle (obtained directly from wood) was determinated and compared with that of particle obtained by mechanical disintegration (M) or thermohydrolytical degredation (T-) of UF-bonded particleboards]2005Ingår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 63, nr 5, s. 390-391Artikel i tidskrift (Refereegranskat)
    Abstract [de]

    Das Wasserrückhaltevermögen nimmt mit Verlängerung der Lagerungsdauer im Wasser zu, wobei die Zunahme im Falle der mechanisch gewonnenen Recyclingspäne (M) besonders ausge- prägt und im Falle der thermohydrolytisch gewonnenen Späne (T) auffallend gering war. Gegenüber den direkt aus Holz gewonnenen Spänen weisen die mechanisch gewonnenen (M) besonders niedrige WRV-Werte auf. Durch die thermohydrolytische Behandlung der Späne, bei der erhebliche Teile des Bindemittels abgebaut werden, nimmtdas  Wasserrückhaltevermögen  deutlich  zu  und  erreicht  sogar Werte,  die  höher  liegen  als  die  von  „frischen“  Spänen.  Für den Abbau des UF-Harzes infolge der thermischen Behandlung spricht auch der gegenüber den mechanisch gewonnenen Spänen (M) niedrigere Stickstoffgehalt der thermohydrolytisch erzeug- ten Späne (T). Es ist nicht auszuschließen, dass während der ther- mohydrolytischen Behandlung ebenfalls Acetylgruppen im Holz abgespalten werden, die zu einer zunehmenden Hydrophilie der Späne führen. Auf einen Abbau von Acetylgruppen deutet der vergleichsweise hohe Gehalt an Essigsäure in den Kaltwasserex- trakten der Späne hin, der nach der Thermohydrolyse festgestellt wurde.

     

  • 207.
    Hameed, Mahmood
    et al.
    Damascus University, Syria.
    Mosseily, Ihssan
    The Possibility of Producing Particleboard from Wastes by-Product of Olives and Determination of its physical- and mechanical Properties2012Ingår i: Minia Journal of Agricultural Research and Development, ISSN 1110-0257, Vol. 32, nr 6, s. 1087-10104Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This investigation has established the possibility of producing Particleboard from Byrene (waste after the oil has been extracted from the second time with Naphtha). This product has good physical-[moisture content (6.1%). density (0.73). absorption and cross-swelling after 2 hours (29.8%:12.6%) and after 24 hours (40.1%:19.1%)] and mechanical properties [binding strength (8.3 N/mm2) and cross-tensile strength (0.23 N/mm2)] according to European Norms and is very economical. 

  • 208.
    Hameed, Mahmood
    et al.
    Georg-August-Universität Göttingen, Germany.
    Roffael, Edmone
    Georg-August-Universität Göttingen, Germany.
    Eindringtiefe verschiedener Bindemittel in Splintholz- und Kernholzspänen der Kiefer (Pinus sylvestris L.): [On the penetrability of various glues from sap- and heartwood of Pine (Pinus sylvesteis L.)]2001Ingår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 58, nr 6, s. 432-436Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Investigation of the penetrability of various glues [urea-formaldehyde resin (UP-resin), phenol-formaldehyde resin (PP-resin), melamine-urea-phenol-formaldehyde made of pine sapwood and heartwood revealed: the various glues penetrate chips from pine sapwood regardless of tree age, height of the sample studied and surface structure deeper than in those made of heartwood. The various glues more deeply penetrate chips from sapwood and heartwood of the 48-year-old pine than chips from sapwood and heartwood of the 124-year-old pine. The penetrability of various glues in chips from sapwood and heartwood of the 124-year-old pine increases with increasing height of the sample studied. Moreover,  glues penetrate sanded surfaces of chips from sapwood and heartwood of the 48- und the 124-year-old pine to a lesser extent than unsanded chip surfaces.

  • 209.
    Hameed, Mahmood
    et al.
    University of Göttingen, Germany.
    Roffael, Edmone
    University of Göttingen, Germany.
    Veränderung des Gehaltes an Ethanol-Cyclohexan-Extrakten von Kiefernsplint- und kernholzspänen infolge thermischer Behandlung: [Decrease in the extractive content (ethanol-cyclohexane) of Chips from sapwood and heartwood of Pine (Pinus sylvestris L.) due to thermal treatment]1999Ingår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 57, nr 4, s. 294-295Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Decrease in the extractive content (ethanol-cyclohexane) of Chips from sapwood and heartwood of Pine (Pinus sylvestris L.) due to thermal treatment at 103 °C. 

  • 210.
    Hameed, Mahmood
    et al.
    University of Göttingen, Germany.
    Roffael, Edmone
    University of Göttingen, Germany.
    Voruntersuchungen zum Einfluß der anatomischen Schnittrichtung auf die Verleimbarkeit des Splint- und Kernholzes der Kiefer (P. sylvestris L.): [Influence of anatomical Wood section on the Gluing of Sap- and heartwood of Pine (Pinus sylvestris L.) with UF-resins]2000Ingår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 58, nr 5, s. 306-307Artikel i tidskrift (Refereegranskat)
    Abstract [de]

    Die Scherfestigkeitswerte von UF-Harz-gebundenem Kiefernsplint- und -kernholz sind in Abhängigkeit von der anatomischen Richtung in der Tabelle 2 zusammengestellt. Daraus geht hervor:

    1. Die Scherfestigkeit der Klötzchenpaare  aus dem Splintholz ist höher als die des Kernholzes  in den entsprechenden anato-mischen Richtungen.

  • 211.
    Hameed, Mahmood
    et al.
    Georg-August-Universität Göttingen, Germany.
    Roffael, Edmone
    Georg-August-Universität Göttingen, Germany.
    Über die Benetzbarkeit von Splint- und Kernholz der Kiefer, Douglasie und Lärche: [On the Wettability of sapwood and heartwood of various woods pieces (Pine, Douglas fir and Larch)]1999Ingår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 57, nr 4, s. 287-293Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    On the wettability of sapwood and heartwood of various woodspecies (Pine, Douglas fir and larch) Results have established that the wettability of sapwood from three woodspecies (Pine, Douglas ®r and Larch) on the cross, radial and tangential section with water and various glues (UF-resins, PF-resins, MUPF-resins and PMDI-adhesive) is better than that of heartwood. In most cases, the tangential section in sapwood and heartwood was less wettable than radial and cross sections. Using alkaline phenolic resins which cause wood to swell, wettability in the tangential direction was improved.

  • 212.
    Hameed, Mahmood
    et al.
    Damascus University, Syria.
    Roffael, Edmone
    Kraft, Redelf
    Freier Harnstoff in alten Spanplatten nachweisbar: Zusammenhang zwischen chemischer Zusammensetzung des Härters und dem Gehalt an freiem Harnstoff wahrscheinlich: [Content of free urea in old particleboards bonded with UF-Resins]2006Ingår i: Holz-Zentralblatt, ISSN 0018-3792, Vol. 132, nr 45, s. 1320-1321Artikel i tidskrift (Refereegranskat)
  • 213.
    Hameed, Mahmood
    et al.
    Damascus University, Syria.
    Roffael, Edmone
    Kraft, Redelf
    On the formation of formaldehyde, furfural and formic acid by thermo hydrolytic treatment of monomeric sugars  (xylose, arabinose and galactose ) . Contribution to the formation of volatile organic compounds (VOC) during thermo-mechanical pulping2007Ingår i: Holztechnologie, ISSN 0018-3881, Vol. 48, nr 3, s. 15-18Artikel i tidskrift (Refereegranskat)
    Abstract [de]

    Bildung von Formaldehyd, Furfural und Ameisensäure bei der thermohydrolytischen Behandlung von einigen monomeren Zuckern (Xylose, Arabinose und Galactose); Beitrag zu Entstehung von flüchtigen organischen Verbindungen (VOC) beim Holzaufschluss für die MDF-Herstellung

     

    Die thermomechanische Behandlung (TMP) von Holz bei der Herstellung von mitteldichten Faserplatten (MDF) führt, wie bekannt, zur Bildung von niedermolekularen Kohlenhydraten einschließlich monomeren Zuckern, die hauptsächlich den Hemicellulosen entstammen. Ergebnisse von orientierenden Voruntersuchungen lassen den Schluss zu, dass aus den monomeren Zuckern bereits bei 100 grd C Furfural, Formaldehyd und Ameisensäure entstehen. Der Gehalt an Formaldehyd, Furfural und Ameisensäure nimmt mit Erhöhung der Temperatur von 100 grd C auf 160 grd C deutlich zu. Die Pen-tosen scheinen weitaus stärker Ameisensäure, Formaldehyd und Furfural zu bilden, als die Hexosen.

     

    Erschienen in Heft 3/2007, S. 15 - 18

  • 214.
    Hellmich, Christian
    et al.
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    Role of Water in Cell Walls of the Hierarchical Composite "Softwood": A Poroelastic Analysis2011Ingår i: Engineering Mechanics Institute 2011 Conference (EMI 2011), Bonston, 2011, s. 195-Konferensbidrag (Övrigt vetenskapligt)
  • 215.
    Hemmilä, Venla
    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).
    Karlsson, Olov
    Luleå university of technology.
    Kumar, Anuj
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Development of sustainable bio-adhesives for engineered wood panels – A review2017Ingår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, nr 61, s. 38604-38630Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 216.
    Hemmilä, Venla
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Hosseinpourpia, Reza
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Eceiza, Arantxa
    Univ Basque Country, Spain.
    Characterization of Wood-based Industrial Biorefinery Lignosulfonates and Supercritical Water Hydrolysis Lignin2019Ingår i: Waste and Biomass Valorization, ISSN 1877-2641, E-ISSN 1877-265X, s. 1-11Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Understanding the properties of any particular biorefinery or pulping residue lignin is crucial when choosing the right lignin for the right end use. In this paper, three different residual lignin types [supercritical water hydrolysis lignin (SCWH), ammonium lignosulfonate (A-LS), and sodium lignosulfonate (S-LS)] were evaluated for their chemical structure, thermal properties and water vapor adsorption behavior. SCWH lignin was found to have a high amount of phenolic hydroxyl groups and the highest amount of beta-O-4 linkages. Combined with a low ash content, it shows potential to be used for conversion into aromatic or platform chemicals. A-LS and S-LS had more aliphatic hydroxyl groups, aliphatic double bonds and C=O structures. All lignins had available C-3/C-5 positions, which can increase reactivity towards adhesive precursors. The glass transition temperature (T-g) data indicated that the SCWH and S-LS lignin types can be suitable for production of carbon fibers. Lignosulfonates exhibited considerable higher water vapor adsorption as compared to the SCWH lignin. In conclusion, this study demonstrated that the SCWH differed greatly from the lignosulfonates in purity, chemical structure, thermal stability and water sorption behavior. SCWH lignin showed great potential as raw material for aromatic compounds, carbon fibers, adhesives or polymers. Lignosulfonates are less suited for conversion into chemicals or carbon fibers, but due to the high amount of aliphatic hydroxyl groups, they can potentially be modified or used as adhesives, dispersants, or reinforcement material in polymers. For most value-adding applications, energy-intensive purification of the lignosulfonates would be required. [GRAPHICS] .

  • 217.
    Hemmilä, Venla
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Meyer, Bettina
    Fraunhofer WKI, Germany.
    Larsen, Annelise
    IKEA of Sweden AB, Sweden.
    Schwab, Harald
    Fraunhofer WKI, Germany.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Influencing factors, repeatability and correlation of chamber methods in measuring formaldehyde emissions from fiber- and particleboards2019Ingår i: International Journal of Adhesion and Adhesives, ISSN 0143-7496, E-ISSN 1879-0127, Vol. 95, s. 1-9, artikel-id 102420Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recently, there has been focus on lowering emission levels of wood-based boards. However, the accuracy and correlationbetween EN 717-1 and ASTM D 6007 chamber methods at emission levels below 0.05 ppm are not wellinvestigated, and information about their correlation to the EN 16516 method is limited. In this paper, the lowemission level of interest was determined by measuring emissions from particles, fibers and pressed boards withoutglue. The effect of analytical methods and edge-sealing on chamber emissions was determined, and accuracies andcorrelations of the EN 717-1 and ASTM D 6007 chambers were defined at low emission levels (< 0.05 ppm). Inaddition, some emission values were compared to those obtained with EN 16516. The EN 717-1 and ASTM D 6007methods had high accuracy. The acetyl acetone and 2.4-dinitrophenylhydrazine analytical methods showed lowstandard deviations (< 5%), except at emission levels below 0.02 ppm. This could be counteracted by using a directreagent absorber solution. Opening 5% of the edge of boards affected emissions and was dependent on board type.ASTM D 6007 and EN 717-1 methods were highly correlated for both particleboards (r2=0.9167) and fiberboards(r2=0.9443) at emission levels below 0.05 ppm. EN 16516 emissions were 2.6 times greater than those of EN 717-1 at emission range<0.05 ppm, exceeding the conversion factor of two given in the German legislation. The EN 717-1 to EN 16516 correlation needs to be further evaluated for different board types and emission ranges

  • 218.
    Hemmilä, Venla
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Trischler, Johann
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Luleå University of Technology.
    Bio-based adhesives for the wood industry: an opportunity for the future?2013Ingår i: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 9, nr 4, s. 118-125Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper reviews the use of some of the new technologies that may be implemented in bio-based adhesives, e.g. carbohydrate polymers, proteins, tannins, lignins, and vegetable oils.

    In order to take a part of the market share, an adhesive should have low production costs, fulfil the environmental and health standards and give better properties than conventional synthetic adhesives. For large-volume wood products such as chipboard, it is essential to develop adhesives that enable the product to be cost competitive. Bio-based adhesives that are available and affordable for the wood industry suffer from three main problems: low moisture resistance, low reactivity and poor adhesive properties, and in several cases they are expensive compared to synthetic adhesives.

  • 219.
    Hemmilä, Venla
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Trischler, Johann
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Lignin: an adhesive raw material of the future or waste of research energy?2013Ingår i: Northern European Network for Wood Science and Engineering (WSE): Proceedings of the 9th meeting, September 11-12, 2013, Hannover, Germany / [ed] Brischke, Christian & Meyer, Linda, Hannover: Leibniz Universität , 2013, s. 98-103Konferensbidrag (Refereegranskat)
    Abstract [en]

    Lignin has been studied as an adhesive for more than 100 years, but there are only a few industrial applications. The reason for the current interest is the high availability and low price of lignin. Lignin is the main by-product of paper pulping processes and is typically burned as fuel. Being the natural glue in plants and having a phenolic nature makes lignins an attractive replacement for wood adhesives.

     

    An adhesive system for wood composites consisting mainly of lignin has yet to be developed. Lignin has less reactive sites in the aromatic ring than phenols, and the steric effects caused by the macromolecular structure further hinder its reactivity. The low reactivity leads to slow curing and causes problems in applications where the curing speed is a critical parameter. Modifications such as phenolation, methylolation, and demethylation have been shown to have a positive impact on the reactivity of lignin.

     

    This paper presents properties of particle boards produced using unmodified and oxidized Kraft lignin adhesives. The paper also describes recent research relating to lignin as a base for wood adhesive and discusses the possibilities for future research.

     

    The boards produced with unmodified and modified lignin adhesives under equivalent pressing conditions performed poorly compared to the reference board made with standard UMF adhesive. Oxidation at the correct pH level improved the adhesion of the boards compared with those based on unmodified lignin. Efforts to produce an industrially viable lignin-based adhesive system will continue, and promising combinations of modifications and alternative hardeners are being studied.

  • 220.
    Hemmilä, Venla
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Zabka, Michal
    IKEA Sweden.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Evaluation of dynamic microchamber as a quick factory formaldehyde emission control method for industrial particleboards2018Ingår i: Advances in Materials Science and Engineering, ISSN 1687-8434, E-ISSN 1687-8442, artikel-id 4582383Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The most common formaldehyde control method for wood panels in Europe, the perforator method, measures formaldehyde content, while most of the legal requirements in the world are based on emissions. Chamber methods typically used for emission measurements require too much time to reach steady state for factory quality control. The aim of this study was therefore to investigate whether emission values of particleboards measured one day after production would be usable for quality control purposes. The correlation between 1-day and 7-day emission values was determined using a dynamic microchamber (DMC). Three industrial board types that differed in density and emission levels were used for the evaluation. The online emission measuring equipment Aero-laser AL4021 connected to the 1 m3 chamber was used to gain further information on the emission reduction behaviour of the different board types. Only the two particleboard types with higher densities showed good correlation between the 1-day and 7-day emissions. The overall results suggested that 1-day emission values can be used for factory quality control purposes; however, if the initial 1-day values are above the permitted level, extensive evaluation for each individual board type needs to be performed

  • 221.
    Herdinius, Andreas
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    En undersökning av möjliga tillväxtmiljöer vid den tidiga sågverkshanteringen av ek2019Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Trä är ett biologiskt och organiskt material vars egenskaper möjliggör att det vid rätt förhållanden kan växa mögel på det. Mögeltillväxt på trä som människor hanterar och har i sin närhet kan skapa hälsoproblem då vissa mögelarter kan orsaka respiratoriska problem samt allergisk alveolit.En undersökning av vilken mögelsvamp som växer på brädor vid ett sågverk i södra Sverige har utförts. Utöver detta har möjliga tillväxtmiljöer för mögel undersökts under brädgårdstorkning samt en torkprocess. De undersökta parametrarna var temperatur och relativ luftfuktighet.Mögelsvampen Paecilomyces hittades samt Aspergillus niger och jäst. Klimatet under brädgårdstorkning samt torkprocessen visade att de under stor del av den tidiga hanteringen av virket fanns ett klimat gynnsamt för mögeltillväxt.

  • 222.
    Hochreiner, G.
    et al.
    Vienna University of Technology, Austria.
    Füssl, J.
    Vienna University of Technology, Austria.
    Serrano, Erik
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Eberhardsteiner, J.
    Vienna University of Technology, Austria.
    Influence of Wooden Board Strength Class on the Performance of Cross-laminated Timber Plates Investigated by Means of Full-field Deformation Measurements2014Ingår i: Strain, ISSN 0039-2103, E-ISSN 1475-1305, Vol. 50, nr 2, s. 161-173Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Although cross-laminated timber (CLT) plates are increasingly used in high-performance building structures, a tailored composition of them or, at least, a performance-based classification scheme is not available. Especially, the influence of the quality of the ‘raw’ material (wooden boards) on the load carrying capacity of CLT elements is hardly investigated yet. For this reason, within this work, bending tests on 24 CLT plates consisting of wooden boards from three different strength classes have been carried out. The global mechanical response as well as the formation of failure mechanisms were investigated, including a full-field deformation measurement system, which allowed for a qualitatively as well as quantitatively identification of board failure modes. Interestingly, no influence of the board strength class on the elastic limit load of the CLT plates was observed, but the situation was different for the load displacement history beyond the elastic regime, where basically, two different global failure mechanisms could be distinguished. The obtained knowledge about the ‘post-elastic’ behaviour of CLT plates may serve as a basis for the optimisation of CLT products and the development or improvement of design concepts, respectively. Moreover, the obtained large ‘post-elastic’ capacity reserve of CLT consisting of high quality boards could lead to a better utilisation of the raw material.

  • 223. Hochreiner, Georg
    et al.
    Bader, Thomas K.
    de Borst, Karin
    Eberhardsteiner, Josef
    Stiftförmige Verbindungsmittel im EC5 und baustatische Modellbildung mittels kommerzieller Statiksoftware2013Ingår i: Bauingenieur: Zeitschrift für das gesamte Bauwesen, ISSN 0005-6650, E-ISSN 1436-4867, Vol. 88, s. 275-289Artikel i tidskrift (Refereegranskat)
  • 224.
    Hochreiner, Georg
    et al.
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Schweigler, Michael
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    Structural behaviour and design of dowel groups: experimental and numerical identification of stress states and failure mechanisms of the surrounding timber matrix2017Ingår i: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 131, s. 421-437Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dowel-type fasteners in combination with steel plates are widely used in engineered timber structures. Since dowel groups are designed as semi-rigid connections subjected to an arbitrary set of internal forces, the corresponding structural behaviour of the surrounding timber matrix must be considered in the design process accordingly, including the effect of reinforcements. Corresponding stress states and failure mechanisms in the timber matrix of dowel groups are discussed herein. Surface strain fields from tests of dowel groups under complex loading situations were used to identify the sequence of cracking, as well as to assign the related failure modes. First cracking events were caused by stress peaks at the most loaded dowels and by a combination of shear stresses and stresses perpendicular to the grain, while later crack- ing events were associated with a predominant action of individual stress components. Thus, the non- linear global moment-relative rotation behaviour of dowel groups could be related to failure mechanisms in the surrounding timber matrix. The corresponding strain state was qualitatively as well as quantita- tively reproduced by means of a numerical model, which gave access to stresses in the timber matrix and has potential to be implemented as a sub-model in engineering design software. The numerical model supported the feasibility of a decomposition of the stress state due to the global bending moment into stresses caused by a couple of equal forces parallel and perpendicular to the grain, which could be used in the design process. Based on experimental and numerical findings, essential aspects for a design procedure for the timber matrix in dowel groups loaded by a combination of internal forces are proposed. 

  • 225.
    Hochreiner, Georg
    et al.
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Schweigler, Michael
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    Timber Matrix Failure Modes in Multi-Dowel Connections2016Ingår i: 17th International Conference on Experimental Mechanics, Rhodes, Greece, July 3-7, 2016, 2016Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    The engineering design of dowel type steel-to-timber connections is comprehensive and shall also include the surrounding timber matrix, as required by the principles specified in Eurocode 5. As one part of a hierarchically structured research program, the loading and failure modes of multi-dowel connections has been investigated, including both the elastic as well as the cracked domain of the load history. Depending on the presence of local reinforcement, in order to prevent premature brittle failure and to insure local ductile dowel behavior, the global response became more or less ductile. The monitoring of surface deformations of the timber by means of a contact free displacement measurement system (DIC) supported the identification of stepwise changing structural systems. This data constitutes a valuable basement for the completion resp. improvement of the present design procedures with respect to consistency and effectiveness.

  • 226. Hochreiner, Georg
    et al.
    Bader, Thomas K.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Schweigler, Michael
    Esser, Gerold
    Hagmann, Stefan
    Glatz, Bernhard
    The Historic Roof Structure of the Spanish Riding School in Vienna: Structural Assessment2015Ingår i: Proceedings of the International Conference on Structural Health Assessment of Timber Structures, SHATIS15, Dolnoslaskie Wydawnictwo Edukacyjne (DWE) , 2015, s. 248-259Konferensbidrag (Refereegranskat)
    Abstract [en]

    In 2012, the historical roof structure of the Spanish Riding School, built in the years from 1729 to 1735 as part of the ensemble of the Vienna Imperial Palace (called Hofburg), was documented by students and staff of the Vienna University of Technology. The survey was performed deformation- accurate and included both, the main structure and corresponding joints. Consequently, the documentation highlights deviations from the initial perception of the roof structure such as broken joints, inactivity of compressive devices like knee braces or excessive displacements of single structural members. Probably, these damages led to strengthening measures (=additional substructures) that were added in recent times to avoid progressive failure. This documentation formed the basis for the assessment of this historical roof structure from a structural and timber engineering point of view, which will be presented herein. The focus of the structural modelling was placed on the assessment of the two initial structural concepts, namely the main hall with and without the timber dome structure that was added in 1734, by visualisation of the internal forces and displacements. For this purpose, the nonlinear load carrying capacities and failure modes of the carpentry joints were assessed. Subsequently, alternative structural systems could be found by iterative recalculation revealing the capabilities for redundancy of the timber roof structure. Corresponding results were checked again with in-situ observations. Consequently, the findings of this study highlight the benefits of integrating modern structural and timber engineering methods and tools in the context of building history and building survey.

  • 227.
    Hochreiner, Georg
    et al.
    Vienna University of Technology, Austria.
    Schweigler, Michael
    Vienna University of Technology, Austria.
    Riedl, Christian
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    Matrix Failure of Multi-Dowel Type Connections Engineering Modelling and Parameter Study2016Ingår i: Proceedings of the 2016 World Conference on Timber Engineering (WCTE), Vienna: Vienna University of Technology , 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    A simplified numerical engineering model for the design of the surrounding timber matrix of dowel groups, developed within the framework of a commercial structural analysis software, is presented herein. This model was applied to highlight and reflect various dowel arrangements in timber to steel connections from building practice subjected to arbitrary sets of internal forces against the background of both the real mechanical behavior and the present practice of design. A parameter study revealed the interdependence of stresses in the timber matrix and geometrical and mechanical properties of dowel groups.

  • 228.
    Hofstetter, Karin
    et al.
    Vienna University of Technology, Austria.
    Eitelberger, Johannes
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Hellmich, Christian
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    Computational Multiscale Approach to the Mechanical Behavior and Transport Behavior of Wood2009Ingår i: Computational Structural Engineering: Proceedings of the International Symposium on Computational Structural Engineering, held in Shanghai, China, June 22–24, 2009, Springer, 2009, s. 79-85Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Moisture considerably affects the macroscopic material behavior of wood. Since moisture takes effect on wood at various length scales, a computational multiscale approach is presented in this paper in order to explain and mathematically describe the macroscopic mechanical and transport behavior of wood. Such an approach allows for appropriate consideration of the underlying physical phenomena and for the suitable representation of the influence of microstructural characteristics of individual wood tissues on the macroscopic behavior. Continuum (poro-)micromechanics is applied as homogenization technique in order to link properties at different length scales. Building the model on universal constituents with tissue-independent properties and on universal building patterns, the only tissue-dependent input parameters are wood species, mass density, moisture content, and temperature. All these parameters are easily accessible, what renders the models powerful and easily applicable tools for practical timber engineering.

  • 229.
    Hofstetter, Karin
    et al.
    Vienna University of Technology, Austria.
    Hellmich, Christian
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    Poro-micromechanical Estimates for Elastic Limit States of Wood2008Ingår i: Eleventh East Asia-Pacific Conference on Structural Engineering and Construction, Taipei, Taiwan, 2008, s. 550-551Konferensbidrag (Övrigt vetenskapligt)
  • 230. Hofstetter, Karin
    et al.
    Hellmich, Christian
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Relevance of Microstructural Failure Mechanismus for Macroscopic Elastic Limit States of Wood2008Konferensbidrag (Övrigt vetenskapligt)
  • 231.
    Holmberg, Hans
    et al.
    KTH Träteknologi.
    Sandberg, Dick
    KTH.
    Diagrambilaga till Rapport KTH-Trä TRITA-TRÄ R-95-12.1995Rapport (Övrigt vetenskapligt)
  • 232.
    Holmberg, Hans
    et al.
    KTH Träteknologi.
    Sandberg, Dick
    KTH Träteknologi.
    Kvistars frekvens, form och beskaffenhet i trekantprofil av furu (Pinus silvestris L) och gran (Picea abies Karst).1995Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Frequency and Character of Knots in Triangular Profiles of Pine (Pinus silvestris L) and Spruce (Picea abies Karst).

    by

    Hans

    Holmberg Dick Sandberg

    Abstract

    This report describes the structure and amount of knots in triangular profiles from StarSawing of pine (Pinus silvestris L) and spruce (Picea abies Karst). The yield of blanks is determined mainly with a defined knot structure and the fibre aberration around knots. In addition a minor investigation of the amount of pitch pockets has been carried out.

    The specimens comprise of butt logs from three different areas in Sweden. The specimens are taken from normal grown pine, and both normal and fast grown spruce.

    Large amounts of the knots found in triangular profiles from butt logs are unacceptable for further refinement. Thus, the knots have to be removed. When producing blanks free from knots there is a volume decrease of 8 and 21 percent in average for pine and spruce respectively, referring to the original volume. Further refinement including fibre aberration increases the volume loss by another 5 percent for pine and 6 percent for spruce. The length of the refined blanks varies between 2 and 500 centimetres for pine and between 2 and 400 centimetres for spruce.

    Measurement results are included in the report for calculating the volume yield of blanks free from knots, with or without fibre aberration. The distributions of lengths of blanks and corresponding volume yields are shown in different graphs.

  • 233.
    Holmberg, Hans
    et al.
    KTH Träteknologi.
    Sandberg, Dick
    KTH Träteknologi.
    Structure and Properties of Scandinavian Timber1997Rapport (Övrig (populärvetenskap, debatt, mm))
  • 234.
    Holmberg, Hans
    et al.
    KTH Träteknologi.
    Sandberg, Dick
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Transportprocesser i trä.: Permeabilitet.1997Rapport (Övrigt vetenskapligt)
  • 235.
    Holmberg, Hans
    et al.
    KTH Träteknologi.
    Sandberg, Dick
    KTH, Träteknologi.
    Utvärdering av en ny ströläggningsmetod för stjärnsågad trekantprofil.1995Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    En ny typ av ströläggning för trekantprofiler har undersökts. Profilema har torkats i buntar om tre där man alltid har lagt de tangentiella sidoma inåtvända för att minska risken för sprickbiIdning.

    Trekantprofilema som undersökts hade sidomåttet 120 mm. Torken som använts var en kammartork som styrs med ett torkschemat anpassat för furu med tjockleken 100 mm. Slutfuktkvoten var avsedd att bli 18 % om man torkat 100 mm virke.

    Efter torkning har prover tagits i rot, mitt och topp för att mata fuktkvotsgradienten i virket. I samband med fuktkvotsmätningen har även densiteten för virket bestämts. Resultaten visar att furu erhåller en större fuktkvotsgradient an gran för det parti som undersökts. Medelfuktkvoten för furn var efter torkning 15,8 % medan gran erhöll en medelfuktkvot på 13,0 %. Fuktkvotsskillnaden mellan torraste och fuktigaste parti i tvärsnittet var för furu 6,4 % och för gran 2,1 %.

    I undersökningen jämfördes trekantprofilemas slutfuktkvot med avsseende på placering i grupperna och med avseende på densitet. Med ett 95 % konfidensintervall kan man inte säkerställa att det finns skillnad mellan de olika placeringama i gruppen. Det går vidare inte att finna några samband mellan densiteten för virket och dess slutfuktkvot.

    En undersökning av ungefär tio kubikmeter virke visar att cirka 15 % av de torkade trekantprofilerma hade lättare angrepp av mögelsvampar. Mindre an 5 % av det genomgångna virket hade angrepp av blånad. Tryckskador fran strön förekom på två tredjedelar av virket och dessa skador kan i många fall härledas till dåIig måttnoggrannhet på profilema.

  • 236.
    Holmberg, Hans
    et al.
    KTH Träteknologi.
    Sandberg, Dick
    KTH.
    Volym- och kvalitetsutbyte vid stjärnsågning.1996Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Volume yield and quality of timber when using Star-sawing technique

    by

    Hans Holmberg and Dick Sandberg

    Abstract

    Volume yield and quality are investigated when starsawing logs of pine (Pinus silvestris L) and spruce (Picea abies Karst). Topdiameters of timber were for pine sorted in two classes 260-300 rnm and 300-340 mm. Spruce timber were sorted in one class with top diameters between 290 and 340 mm.

    The investigation shows a volume yield considerably higher for starsawing compared to conventional techniques. This investigation, carried out on a simple testplant, yields 68 %calculated from top volume of log. Volume yield calculated from a cone with top and root diameters is 56 %. With sideboards included these numbers will incerease with one percent. The triangular profiles is 47 % of the total volume and the rest 53 % are quarter sawn boards.

    The volume yield of spruce is about one percent higher than for pine. The difference is assumed to depend on more pronounced taper of the log in spruce, wich allows easier positioning of the log.

    Quality is determined with a method developed especially for quarter sawn timber.

     

  • 237.
    Holmberg, Hans
    et al.
    KTH.
    Sandberg, Dick
    KTH.
    Volymutbyte vid tillverkning av furulimfog från stjärnsågad trekantsprofil.1997Rapport (Övrigt vetenskapligt)
    Abstract [da]

    Volume yield in manufacturing gluelam board of Scots pine from star-sawn triangular profiles.

    by

    H.Holmberg

    D. Sandberg

    Abstract

    Triangular profiles from star-sawing have been used to produce knot free gluelam boards with radial surfaces and a length of 2.1 m. The volume yield has been evaluated in two different gluelam qualities. One was with finger joints and the other one without finger joints. The material used was 7.78 mtriangular profiles of pine. The quality and dimension was sawfallen. The manufacture of the profiles has been carried out in five steps:

    1. Removal of knots and defects.
    2. Finger jointing of cut pieces.
    3. Planing of triangular profiles.
    4. Clueing of triangular profiles into blocks.
    5. Splitting the blocks into gluelam boards and finishing the surface.

    The measurements comprises all steps except splitting and final finishing. These steps have been simulated theoretically.

    The total volume yield was 53.8 %. In the process three operations were found to be critical for the result. They are: removal of knots and defects, planing and splitting of blocks and finishing. These operations account for more than 93 % of the total loss during manufacturing.

    Removal of knots and defects resulted in 12,8 % loss of volume. 13 % of the manufactured blocks were without knots, defects and finger joints. The average length of the pieces after cutting was 0,41 m.

  • 238.
    Hosseinpourpia, Reza
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). University of Göttingen, Germany.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Holstein, Nonna
    University of Göttingen, Germany.
    Mai, Carsten
    University of Göttingen, Germany.
    Dynamic vapour sorption and water-related properties of thermally modified Scots pine (Pinus sylvestris L.) wood pre-treated with proton acid2017Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 138, s. 161-168Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study investigates the effect of proton acid pre-treatment and subsequent thermal modification at relatively low temperatures (up to 180 °C) on wood with respect to dimensional stability and water vapour sorption properties. The effects are compared to those of solely thermally-modified wood at higher temperatures (up to 250 °C). Scots pine sapwood (P. sylvestris L.) was impregnated with a proton acid or demineralised water, and subsequently, thermally modified to various mass losses (ML). Acid pre-treatment and thermal modification improved the dimensional stability and reduced the equilibrium moisture content (EMC) until certain ML. Excess surface work (ESW) obtained from vapour sorption studies indicated that, at comparable ML, the acid pre-treatment reduced the available sorption sites as compared to sole thermal treatment. Samples pre-treated with acid also showed stronger decreasing courses of EMC- and ESW-ratios than sole thermally modified ones. This was attributed to degradation of amorphous wood polymers and a stiffer matrix due to cross-linking of the cell wall polymers as a consequence of acid pre-treatment. Electron spin resonance (ESR) analysis indicated that acid pre-treatment did not enhance the concentration of phenoxy radicals, whereas thermally modified wood showed a considerably higher concentration of phenoxy radicals, suggesting that high radical density cannot be used as an indicator for high matrix stiffness.

  • 239.
    Hosseinpourpia, Reza
    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).
    Mai, C
    Georg-August-University Gottingen, Germany.
    Analysis of the vapour sorption behaviour of wood modified with thermosetting resins with Hailwood-Horrobin and Excess Surface Work models2018Ingår i: 29th International Conference on Wood Science and Technology, ICWST 2018: Implementation of Wood Science in Woodworking Sector - Proceedings / [ed] Spanic N.,Zupcic I., University of Zagreb , 2018, s. 87-92Konferensbidrag (Refereegranskat)
    Abstract [en]

    Wood modification is a well-known technology to enhance the dimensional stability of wood and the resistance to abiotic and biotic degradation. Impregnation modification of wood with thermosetting resins, such as melamine formaldehyde (MF) or phenol formaldehyde (PF), alters the material properties of wood through formation of a three-dimensional network within the cell wall. This work investigates the vapour sorption behaviour of Scots pine (Pinus sylvestris L.) micro-veneers modified with MF and PF resins by means of Hailwood-Horrobin (H-H) and excess surface work (ESW) models. The analysed sorption data indicated that the available sorption sites were increased in the modified samples compared to the unmodified controls due to an increase of the monolayer sorption. However, modification resulted in a considerable reduction of the multilayer sorption. This could be attributed to the formation of a rigid, three-dimensional corset within the cell wall formed by auto-polymerization reactions of resin monomers and oligomers, which is known to reduce the cell wall swell-ability upon water absorption.

  • 240.
    Hosseinpourpia, Reza
    et al.
    Georg-August-University Göttingen, Germany.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Mai, Carsten
    Georg-August-University Göttingen, Germany.
    Dynamic vapour sorption of wood and holocellulose modified with thermosetting resins2016Ingår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 50, nr 1, s. 165-178Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Micro-veneers of wood and holocellulose (HC) were modified with the thermosetting resins phenol formaldehyde and melamine formaldehyde. The dynamic water vapour sorption of the modified and untreated veneers was studied in a dynamic vapour sorption apparatus to assess the effects of resin modification. The adsorption of wood and HC as well as the desorption of wood was little affected by the modification in the low relative humidity (RH) range but decreased in the RH range above 60–70 %. The desorption isotherm of HC, however, was increased in the RH range of 15–80 % due to modification. Resin modification gradually decreased the EMC ratio of wood and HC and also influenced the moisture increment, equilibrium time and sorption rate in RH range above 50–60 % RH for wood and above 70–80 % RH for HC. HC exhibited a clearly lower hysteresis than wood. Modification of wood slightly reduced hysteresis compared to untreated wood, but modification of HC clearly increased hysteresis about to the same extent as that of wood. This indicates that the stiffening effect of lignin and thermosetting resins reduces the flexibility of the HC matrix, which results in increased hysteresis.

  • 241.
    Hosseinpourpia, Reza
    et al.
    Georg-August-University Göttingen, Germany.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Mai, Carsten
    Georg-August-University Göttingen, Germany.
    Dynamic water vapour sorption properties and dimensional stability of thermally and acid-treated Scots pine (Pinus sylvestris L.)2015Ingår i: 69th Forest Products Society (FPS) International Convention, June 10-12, Atlanta, GA, Forest Products Society , 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    In order to accelerate the thermal modification process, Scots pine sapwood samples were subjected to two types of treatments. One group of samples was impregnated with water and exposed to 220oC and the second group was initially treated with low concentration of acids (1 mol l-1 AlCl3 and a mixture of 0.5 mol l-1 H2SO4 and 1 mol l-1 AlCl3), and then heated at different temperatures (180 and 120oC) to achieve comparable mass loss (ML) levels. The water vapour sorption isotherms of the thermally and acid-treated wood samples were determined using a dynamic vapour sorption (DVS) apparatus. Increasing the temperature in both thermally and acid-treated samples resulted in ML attributable to hemicelluloses degradation. As a result thereof, dimensional stability and reduction in the hygroscopicity of wood were observed. Acid-treated samples heated at lower temperature exhibited similar water sorption behaviour as water-treated samples subjected to considerably higher temperature. The sorption data were analysed using the Hailwood-Horrobin (H-H) and excess surface work (ESW) models. The data indicated that the monolayer and polylayer sorption were reduced by the acid and thermal treatments, but acid treatment reduced the monolyer sorption stronger than the thermal. The effect of thermal and acid treatments on the flexibility of the cell wall matrix could not be fully distinguished.

  • 242.
    Hosseinpourpia, Reza
    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).
    Mai, Carsten
    Effect of lignin and hemicelluloses removal on dynamic water vapour sorption behavior of wood2017Ingår i: IUFRO Division 5 Conference, 12-14 June, 2017 - Vancouver, British Columbia: Final program, proceedings and abstracts, IUFRO Division 5 Conference , 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    Water-related properties of wood are strongly depended on the sorption behavior of its hygroscopic polymers such as cellulose, hemicelluloses and lignin. To assess the sorption performance of wood matrix in the absence of hemicelluloses and lignin, micro-veneers of Scots pine (Pinus sylvestris L.) were hydrolyzed with sulphuric acid and delignified with sodium chlorite and acetic acid, respectively. The dynamic water vapour sorption of the hydrolyzed, delignified and untreated veneers was studied in a dynamic vapour sorption (DVS) apparatus. The moisture adsorption of hydrolyzed veneers was decreased in the relative humidity (RH) range above 60-70 %. Delignified veneers, however, showed obviously higher moisture adsorption at RH above 70%, as compared to untreated controls. Hydrolyzed and untreated veneers exhibited a comparable hysteresis, while delignified veneers showed a considerably lower hysteresis in comparison to them. This explains that, despite the fact that the hydrophilic hemicelluloses influence the moisture sorption of wood, the expand-ability of the cell wall matrix is mainly controlled by lignin.

  • 243.
    Hosseinpourpia, Reza
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Georg-August-University, Germany.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Mai, Carsten
    Georg-August-University, Germany.
    Effects of acid pre-treatments on the swelling and vapor sorption of thermally modified Scots pine (Pinus sylvestris L.) wood2018Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 13, nr 1, s. 331-345Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Scots pine sapwood samples were pre-treated with a Lewis acid (AlCl3) and a combination of Lewis and protonic acids (AlCl3 and H2SO4), and were subsequently exposed to respective temperatures of 180 °C and 120 °C for establishing a comparable mass loss with those impregnated with demineralized water and solely thermally modified at 220 °C. Water impregnated samples dried at 120 °C also served as controls. The swelling behavior of all wood samples was examined with respect to maximum swelling in water, anti-swelling efficiency (ASE), shrinkage, and dynamic water vapor sorption at relative humidity ranges of 0% to 95%. The thermal modification at 220 °C diminished swelling and moisture adsorption, and also reduced moisture increment and decrement compared with the unmodified control. However, it was less obvious than both acid pre-treated samples. Excess surface work and Hailwood-Horrobin results calculated from water vapor sorption studies demonstrated that, at comparable mass loss, the available sorption sites were reduced to a greater extent by Lewis acid and combination of Lewis and protonic acids pre-treatment than the sole thermal treatment. This was attributed to more pronounced degradation of polysaccharides, mainly hemicelluloses and amorphous parts of cellulose, and to cross-linking of cell wall polymers due to the acid pre-treatments.

  • 244.
    Hosseinpourpia, Reza
    et al.
    Georg August University Göttingen, Germany.
    Adamopoulos, Stergios
    Technological Educational Institute of Thessaly, Greece.
    Mai, Carsten
    Georg August University Göttingen, Germany.
    Tensile strength of handsheets from recovered fibers treated with N-methylol melamine and 1,3-dimethylol-4,5-dihydroxyethyleneurea2015Ingår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 132, nr 3, artikel-id 41290Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The main objective of this study was to assess the effect of two amino resins, N-methylol melamine (NMM) and 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU), on the intrafiber and interfiber strengths and water absorption of two types of waste paper categories, office paper (OP), and old corrugated containers (OCCs). The tensile strength of individual fibers measured at zero span was reduced by increases in the resin concentrations. The dry tensile strengths of the recovered handsheets measured at a finite span were enhanced with increases in the weight percentage gain of the resins. The increasing of the resin concentration also significantly improved the intrabonding of the OP and OCCs in moist measuring conditions. The water absorption of the handsheets considerably decreased at the higher concentration of the thermosetting resins, especially with NMM. The results are promising for the use of NMM- and DMDHEU-treated recovered fibers as an alternative fiber resource for the production of laminated paper and also for the use of DMDHEU as a new N-methylol compound for laminated paper.

  • 245.
    Hosseinpourpia, Reza
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Georg-August-University Göttingen, Germany.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Mai, Carsten
    Georg-August-University Göttingen, Germany.
    Hemmilä, Venla
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Effect of Bio-Based Additives on Physico-Mechanical Properties of Medium Density Fibreboards2017Ingår i: 28th ICWST, International Conference on Wood Science and Technology: Implementation of Wood Science in Woodworking Sector, Proceedings. Zagreb, 7th - 8th of December 2017 / [ed] Ivica Zupcic, Vjekoslav Zivkovic, Josip Miklecic, Zagreb: University of Zagreb, Faculty of Forestry , 2017, s. 153-158Konferensbidrag (Refereegranskat)
    Abstract [en]

    Dimensional stability of wood-based panels is generally improved with application of suitable additives. Most of these additives, such as paraffin wax, are petroleum-based and with relatively high cost, and therefore, it is desirable to develop low-cost and effective substitutes from renewable resources. This work studied the potential of using a renewable water-repellent additive, such as tall oil fatty acid, for lab-scale manufacturing of medium density fibreboards (MDF). Tall oil fatty acid (TOFA) was used at 1 and 3% w/w of urea formaldehyde (UF) resin. MDF panels with similar concentrations of paraffin wax (wax) and panels without adding a water-repellent agent were served as controls. It was assessed the dimensional stability of the panels in terms of thickness swelling and water uptake after 4 and 24h immersion in water, and their mechanical performance in terms of modulus of elasticity, modulus of rupture and internal bonding. Results showed no obvious differences in the strength behaviour of the panels by addition of water-repellent agents. Dimensional stability, however, considerably improved by addition of TOFA, but it was still inferior when compared to that provided by wax.   

  • 246.
    Hosseinpourpia, Reza
    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).
    Mai, Carsten
    Georg-August-University Göttingen, Germany.
    Taghiyari, Hamid Reza
    Shahid Rajaee Teacher Training University, Iran.
    Properties of medium-density fibreboards bonded with dextrin-based wood adhesive2019Ingår i: Wood research, ISSN 1336-4561, Vol. 64, nr 2, s. 185-194Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study focuses on manufacturing of medium density fibreboard (MDF) panels bonded with dextrin-based wood adhesive and crosslinked in situ with various weight ratios of synthetic (e.g., polymeric-methane diphenyl-diisocyanate, pMDI) or bio-based (e.g., glyoxal) crosslinkers. The physical and mechanical properties of the panels were evaluated and compared with those from panels without crosslinker (control). Modulus of rupture (MOR) and internal bond (IB) strength of the MDF panels were considerably increased by increasing the crosslinkers’ content. While, slight improvements were observed in modulus of elasticity (MOE) of the panels as a function of crosslinker type and content. Addition of crosslinkers clearly reduced the thickness swelling (TS) and water absorption (WA) of the panels, whereas, the panels with pMDI showed superior performances than the control and glyoxal added ones within 4 h and 24 h immersion in water. The results indicate the potential of dextrin as wood panel adhesive along with the use of appropriate crosslinkers.

  • 247.
    Hosseinpourpia, Reza
    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).
    Parsland, Charlotte
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Utilization of different tall oils for improving the water resistance of cellulosic fibers2019Ingår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 136, nr 13, artikel-id 47303Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study was conducted to assess the effect of the pulping by-products crude tall oil (CTO), distilled tall oil (DTO), andtall oil fatty acid (TOFA) on dynamic water vapor sorption behavior, interfiber strength, and thermal stability of cellulosic paper-sheets.The results were compared against those obtained in cellulose papers treated with the conventional petroleum-derived hydrophobicagent hydrowax and in untreated ones. The tall oil treatments caused strong reduction in equilibrium moisture content of the paper-sheets during adsorption and desorption runs. The same trend was noticed for the hydrowax-treated papers, however, it was lesspronounced than the CTO-treated and DTO-treated samples in the relative humidity range of 75–95%. The sorption hysteresis was con-siderably decreased after the treatments. The ultimate dry-tensile strengths of the paper-sheets were significantly reduced by TOFA andhydrowax treatments, while CTO and DTO showed comparable strength as that of untreated control. The ultimate wet-strengths of thepaper-sheets were improved after the treatments. The thermal stability of the specimens was improved by the tall oil treatments, and thehydrowax-treated samples illustrated lower degradation temperature than the untreated control. The results are promising for the use oftall oils as alternative hydrophobic agents of cellulosicfiber-based products, such as wood panels and paper packaging.

  • 248.
    Hosseinpourpia, Reza
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Echart, Arantzazu Santamaria
    University of the Basque Country UPV/EHU, Spain.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Gabilondo, Nagore
    University of the Basque Country UPV/EHU, Spain.
    Eceiza, Arantxa
    University of the Basque Country UPV/EHU, Spain.
    Modification of Pea Starch and Dextrin Polymers with Isocyanate Functional Groups2018Ingår i: Polymers, ISSN 2073-4360, E-ISSN 2073-4360, Vol. 10, nr 9, artikel-id 939Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pea starch and dextrin polymers were modified through the unequal reactivity of isocyanate groups in isophorone diisocyanate (IPDI) monomer. The presence of both urethane and isocyanate functionalities in starch and dextrin after modification were confirmed by Fourier transform infrared spectroscopy (FTIR) and 13C nuclear magnetic resonance (13C NMR). The degree of substitution (DS) was calculated using elemental analysis data and showed higher DS values in modified dextrin than modified starch. The onsets of thermal degradation and temperatures at maximum mass losses were improved after modification of both starch and dextrin polymers compared to unmodified ones. Glass transition temperatures (Tg) of modified starch and dextrin were lower than unmodified control ones, and this was more pronounced in modified dextrin at a high molar ratio. Dynamic water vapor sorption of starch and dextrin polymers indicated a slight reduction in moisture sorption of modified starch, but considerably lower moisture sorption in modified dextrin as compared to that of unmodified ones.

  • 249.
    Hosseinpourpia, Reza
    et al.
    Islamic Azad University, Iran ; Georg-August University, Germany.
    Hosseini, Payam
    Sharif University of Technology, Iran.
    Mofidian, Seyedehrashin
    Mazandaran University of Science and Technology, Iran.
    Hosseinpourpia, Rezvan
    Islamic Azad University, Iran.
    Varshoee, Ali
    Islamic Azad University, Iran.
    Influence of Nanosilica on Properties of Green Cementitious Composites Filled with Waste Sulfite Pulp Fiber and Aminosilane2014Ingår i: The Arabian Journal for Science and Engineering, ISSN 1319-8025, Vol. 39, nr 4, s. 2631-2640Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Developments in the field of green cement-based products are characterized as an important approach to sustainable development and are being devoted much attention by the construction industry. Numerous types of materials are utilized; however, based on other published studies, the use of waste material as a filler normally deteriorates the performance of cementitious products. Appropriate additives thus need to be employed to improve the performances and properties of green products. As a consequence, the aim of this study has been to investigate the properties of a novel green cement-based composite—a hybrid system composed of cement, waste natural fiber, silica nano-particles, and aminosilane. Experiments were performed to assess the physical properties (density and flowability), mechanical properties (compressive strength and bending performance), and microstructural properties (as determined by scanning electron microscopy) of the cement sheets. The results demonstrated an improvement in the mechanical and microstructural properties of green cement-based composites by using this hybrid system.

  • 250.
    Hosseinpourpia, Reza
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Göttingen university, Germany.
    Mai, Carsten
    Dynamic water vapour sorption properties of wood cell wall polymer constituents2015Ingår i: COST FP1303 (Performance of bio-based building materials) / [ed] Dennis Jones, Christian Brischke, Jaan Kers, Triinu Poltimäe and Joachim Schmid, SP Technical Research Institute of Sweden , 2015, s. 42-44Konferensbidrag (Refereegranskat)
    Abstract [en]

    Lignin, cellulose and hemicelluloses have main roles on swelling and shrinkage of wood products. Interaction of these components with moisture has an important effect on market-friendly when the wood is subjected to the outside utilizations. In the heterogeneous structure of wood, sorption and desorption are occurred in different stages and it calls hysteresis. Hysteresis is a characteristic result from a moisture/temperature/time-dependent, slow, non-equilibrium, swelling-related conformational change, which is facilitated by increasing free volume and mobility in a polymer that is being plasticized during sorption that usually progresses through the stage of water clustering (Reina et al. 2001). Cell wall polymers of wood have a different behavior in the face of moisture in terms of sorption, desorption and hysteresis (Engelund et al. 2013).

    In order to better comprehension of the effect of cell wall material such as lignin, cellulose and hemicelluloses, Scots pine micro-veneers were subjected to hydrolysis with sulphuric acid or delignification with acidic sodium chlorite, as previously described (Klüppel and Mai 2012). Then the hemicelluloses were isolated from the delignified veneers according to the chloride method. The commercial lignin was also used after dialysis tubing. The water adsorption and desorption mechanism of delignified and hydrolysed veneers as well as cell wall polymers such as cellulose, hemicelluloses and lignin were determined using a dynamic vapour sorption (DVS) apparatus.

    The hydrolysed veneers were resulted in obviously lower moisture content in adsorption and desorption processes with increasing the relative humidity (RH) (Fig. 1a). While, delignified veneers showed slightly higher moisture content compared to control with increasing the ambient moisture until 70% RH and then considerably higher until 95% RH. Control specimens shown higher hysteresis than hydrolysed veneers and also higher hysteresis than delignified veneers after hygroscopic range (Fig. 1b). Moisture content of cell wall constituents in various relative humidity exhibited the higher moisture sorption and desorption of cellulose than lignin, however, hemicelluloses illustrated the significantly higher moisture content than other two cell wall polymers which might be attributed to the softening of hemicelluloses in higher relative humidity (Fig. 2a,b,c). Lignin showed higher hysteresis than cellulose in different relative humidity. Hemicellulose demonstrated the relatively low hysteresis until 50% RH, and with increasing the ambient pressure from 60% RH the hemicelluloses exhibited the extremely higher hysteresis than other cell wall polymers.

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