lnu.sePublikasjoner
Endre søk
Begrens søket
123 1 - 50 of 123
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Amiandamhen, Stephen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). University of Benin, Nigeria.
    Agwu, Chiedozie
    University of Benin, Nigeria.
    Ezenwaegbu, Pascal
    University of Benin, Nigeria.
    Evaluation of cement-bonded particleboards produced from mixed sawmill residues2021Inngår i: Journal of the Indian Academy of Wood Science, ISSN 0972-172X, Vol. 18, nr 1, s. 14-19Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study evaluates the application feasibility and properties of cement-bonded particleboards produced from mixed tropical hardwood species. Wood residues from a typical sawmill were collected, dried and used in the manufacturing of the cement composites. The wood residues used were from Ceiba pentandra and Gmelina arborea timber species. The residues were mixed in seven ratios in the production of the composite samples. Two control experimental samples containing unmixed residues of each species were also produced. The test carried out on the boards were flexural strength, water uptake properties and wet and dry screw withdrawal resistance. The effect of the wood mix ratio on the board properties was evaluated. The result showed that all properties except the screw withdrawal resistance were significantly influenced by the mix ratios (p < 0.05). The wet and dry screw withdrawal resistance ranged from 1170 to 1770 N and 1360 to 1830 N, respectively. The optimum wood mix ratio for enhancing mechanical performance of the boards was 1:4 of C. pentandra/G. arborea wood residues. Based on the result of this study, the particleboards produced can be used as wood composite ceiling tiles in building applications.

  • 2.
    Olayiwola, Hamed
    et al.
    Stellenbosch University, South Africa.
    Amiandamhen, Stephen
    Stellenbosch University, South Africa .
    Meincken, Martina
    Stellenbosch University, South Africa.
    Tyhoda, Luvuyo
    Stellenbosch University, South Africa.
    Investigating the suitability of flyash/metakaolin-based geopolymers reinforced with South African alien invasive wood and sugarcane bagasse residues for use in outdoor conditions2021Inngår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 79, s. 611-627Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The prevailing approach of total clearing to contain the spread of invasive plants (IP) in South Africa is generating enormouslignocellulosic wastes. This study examined the possibility of utilizing these wastes in the production of geopolymercomposites for use in outdoor environments. Untreated wood particles from Acacia mearnsii and A. longifolia, as well assugarcane bagasse residues, were incorporated into a geopolymer matrix developed from a binary precursor system of 75%fly ash and 25% metakaolin. The variables considered included precursor-activator ratio (PA), curing pattern (CP), lignocellulosicmaterial (LM), and alkali concentration (Mcon). The production process was established using a mixed factorialexperimental design. PA and CP were considered at 2 levels, while LM and MCon were considered at 3 levels. The densityof the boards exceeded 1 g cm−3 and are classified as high-density boards. The boards have comparable sorption propertiesto the cement-bonded particleboard according to the EN 632-2: 2007 standard. However, only A. longifolia boards producedwith 12 M NaOH and PA ratio of 2:1 met the mechanical strength requirements. Thermogravimetric analysis revealed thatthe boards are thermally stable. These results have shown that South African woody IPs are suitable for geopolymer woodcomposites, but there is still concern about their durability in the alkaline matrix. Scanning electron microscopy micrographsindicated mineralization of the particles and a partial degradation of hemicellulose was confirmed by Fourier transform infraredspectroscopy. Although the degraded components did not prevent geopolymer setting, there is need to further investigatethe extent and means of preventing degradation as this can derail the intended use of the product.

  • 3.
    Chimphango, Anderson
    et al.
    Stellenbosch University, South Africa.
    Amiandamhen, Stephen
    Stellenbosch University, South Africa.
    Görgens, Johann
    Stellenbosch University, South Africa.
    Tyhoda, Luvuyo
    Stellenbosch University, South Africa.
    Prospects for Paper Sludge in Magnesium Phosphate Cement:Composite Board Properties and Techno‑Economic Analysis2021Inngår i: Waste and Biomass Valorization, ISSN 1877-2641, E-ISSN 1877-265X, Vol. 12, s. 5211-5233Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study investigated the feasibility of utilizing paper sludge (PS) as feedstock in the production of composite boards thatare lightweight, durable and environmentally friendly. PS samples were collected from recycled newsprint (RN), corrugatedrecycled (CR) and virgin pulp (VP) pulping mills in South Africa. The PS was dried and mixed with magnesium phosphatecement to produce boards in a central composite design. Three different fillers including fly ash, calcium carbonate and silicafume were also added to the mix as binder replacement. The PS was characterized before use, and the produced compositeboard was evaluated for mechanical and physical properties. The boards produced had medium to high density (0.52—1.12 g/cm3) that could be used for non-structural interior applications. The results showed that boards containing RN had the highestmean value for modulus of elasticity (MOE) of 769 MPa. The mean MOE for boards containing CR- and VP-PS was357 and 411 MPa, respectively. Calcium carbonate had the best effect on the board properties. Techno-economic analysiswas simulated for four different types of feedstock scenarios at different locations including a combined scenario. Sensitivityanalysis revealed that decreased feedstock cost resulted in decreased minimum required selling price. The analysis alsorevealed that the combined scenario proved to be the most cost-effective and profitable option for the future.

  • 4.
    Amiandamhen, Stephen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Adamopoulos, Stergios
    Swedish University of Agricultural Sciences, Sweden.
    Adl-Zarrabi, Bijan
    Chalmers University of Technology, Sweden.
    Yin, Haiyan
    RISE, Sweden.
    Noren, Joakim
    RISE, Sweden.
    Recycling sawmilling wood chips, biomass combustion residues, and tyre fibres into cement-bonded composites: properties of composites and life cycle analysis2021Inngår i: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 297, artikkel-id 123781Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study investigated the properties and sustainability of cement-bonded composites containing industrial residues such as wood chips, tyre fibres and biomass combustion residues, i.e. bottom ash (BA) and fly ash (FA). The effect of cement-to-raw material (wood/tyre fibre) ratio (C/RM) and the aggregate content (BA and FA) on thermal and mechanical properties of the composites were investigated. Scanning electron microscopy (SEM) and life cycle analysis (LCA) were also conducted. The results revealed that as the aggregate content increased in wood composites, the mechanical properties also increased. The mean thermal conductivity and volumetric heat capacity of tyre composite samples were 0.37 W/mK and 1.2 MJ/m3K respectively, while the respective values for wood composite samples were 0.29 W/mK and 0.81 MJ/m3K. SEM analysis showed adequate bonding between wood/tyre fibres and cement matrix. LCA revealed that the materials share of the total primary energy use was about 60% for all analysed composites.

  • 5.
    Amiandamhen, Stephen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Kumar, Anuj
    Natural Resources Institute Finland (Luke), Finland.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Jones, Dennis
    Luleå university of technology, Sweden;Czech university of life sciences Prague, Czech Republic.
    Nilsson, Bengt
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Bioenergy production and utilization in different sectors in Sweden: A state of the art review2020Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 15, nr 4, s. 9834-9857Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the continual desire to reduce the environmental footprints of human activities, research efforts to provide cleaner energy is increasingly becoming vital. The effect of climate change on present and future existence, sustainable processes, and utilizations of renewable resources have been active topics within international discourse. In order to reduce the greenhouse gases emissions from traditional materials and processes, there has been a shift to more environmental friendly alternatives. The conversion of biomass to bioenergy, including biofuels has been considered to contribute to the future of climate change mitigation, although there are concerns about carbon balance from forest utilization. Bioenergy accounts for more than one-third of all energy used in Sweden and biomass has provided about 60% of the fuel for district heating. Apart from heat and electricity supply, the transport sector, with about 30% of global energy use, has a significant role in a sustainable bioenergy system. This review presents the state of the art in the Swedish bioenergy sector based on literature and Swedish Energy Agency’s current statistics. The review also discusses the overall bioenergy production and utilization in different sectors in Sweden. The current potential, challenges, and environmental considerations of bioenergy production are also discussed

    Fulltekst (pdf)
    fulltext
  • 6.
    Alawode, Abiodun
    et al.
    Stellenbosch University, South Africa.
    Eselem-Bungu, Paul
    Stellenbosch University, South Africa .
    Amiandamhen, Stephen
    Stellenbosch University, South Africa.
    Meincken, Martina
    Stellenbosch University, South Africa.
    Tyhoda, Luvuyo
    Stellenbosch University, South Africa.
    Evaluation of Irvingia kernels extract as biobased wood adhesive2020Inngår i: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 66, artikkel-id 12Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Irvingia tree species have been earmarked for domestication in many countries due to their potential as raw materials for various applications, which include biodiesel, cosmetics, perfume, soap, etc. Presently, there is no information on the utilization of kernel seed extract as a potential source of green wood adhesive. This study is focused on investigating the properties of adhesives produced from kernel seeds of two Irvingia wood species i.e. Irvingia gabonensis (IG) and Irvingia wombolu (IW), as well as investigating the improved properties derived from the effect of modification using a few selected modifying agents including glutaraldehyde, glyoxal, epichlorohydrin (EPI) and an acid/base type process modification. Polyethylene (PE) was used along with the glutaraldehyde, glyoxal and epichlorohydrin modifiers in the modification process. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) were conducted to study the effect of modification on adhesive properties. The glycosidic carbon of the unmodified extracts and that of the EPI modified sample were not sensitive to chain conformations. Principal components (PC) 1 and 2 explained 85.19 and 9.54%, respectively, of the total variability in FTIR spectra among the modified and unmodified adhesives. The unmodified samples for IG and IW exhibited one peak with crystallization temperatures of 18.7 and 14.4 °C, respectively, indicating only one component exhibits some low degree crystallinity. The adhesive properties of the modified extracts were tested on wood veneers according to ASTM standard. The shear strength of the modified adhesives ranged from 1.5 to 3.93 MPa and 1.7 to 4.05 MPa for IG and IW, respectively. The modified samples containing PE showed marked improvement in the shear strength. The highest values were about 63% higher than the shear strength of unmodified samples with least shear strength. The results indicated that the modification of Irvingia-based adhesives had a great contribution to their performance as natural wood adhesives.

  • 7.
    Hosseinpourpia, Reza
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Linnéuniversitetet, Kunskapsmiljöer Linné, Avancerade material.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Walther, Thomas
    IKEA Industry AB, Sweden.
    Naydenov, Valeri
    SunPine AB, Sweden.
    Hydrophobic Formulations Based on Tall Oil Distillation Products for High-Density Fiberboards2020Inngår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 13, nr 18, s. 1-13, artikkel-id 4025Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study investigates the effect of renewable formulations based on tall oil bio-refinery products on the water vapor sorption and interfiber strength of cellulosic fibers as well as on the properties of high-density fiberboard (HDF) panels. The results obtained for HDF prepared using renewable formulations were compared to the results for HDF obtained using conventional synthetic paraffin wax (hydrowax), which is the hydrophobic agent currently utilized by the industry. Four tall oil distillation products (TODPs) with different levels of fatty and rosin acids were used for preparing the hydrophobic formulations with furfuryl alcohol as an organic solvent. According to determinations with an automated vapor sorption apparatus, the formulations had a similar effect with hydrowax on the sorption behavior of natural fibers. Unlike to hydrowax treatment, the ultimate tensile strength of cellulosic paper-sheets treated with the formulations remained unchanged or significantly increased. At the standard addition load of 1% (wt/wt dry fibers) of the formulations, HDF panels showed comparable and only in one case, e.g., TODP3-based formulation, slightly higher thickness swelling (24 h) than those with hydrowax. The best performing formulation (TODP2-based) in terms of tensile strength of paper sheets did not significantly change the mechanical properties of HDF panels in both standard climate and high humid conditions. Promising results at the standard and humid climate conditions were obtained for HDF panels manufactured with higher TODP2-based formulation amounts (3-5%) and reduced melamine-urea-formaldehyde resin content (10-12% instead of 14%, wt dry resin/wt dry fibers).

    Fulltekst (pdf)
    fulltext
  • 8.
    Amiandamhen, Stephen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Stellenbosch University, South Africa.
    Meincken, Martina
    Stellenbosch University, South Africa.
    Tyhoda, Luvuyo
    Stellenbosch University, South Africa.
    Natural fibre modification and its influence on fibre-matrix interfacial properties in biocomposite materials2020Inngår i: Fibers And Polymers, ISSN 1229-9197, E-ISSN 1875-0052, Vol. 21, nr 4, s. 677-689Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Biocomposite materials manufactured from natural fibres and polymer matrix represent a group of engineered composite products with diverse applications. These materials continue to find increasing applications due to their design flexibility, superior properties and aesthetic appeal. The applicability of these biocomposites, however, depends on theinteraction in the fibre-matrix interface. This paper reviews the state of the art research in fibre-matrix interfacial interaction based on published literature. A brief background on biocomposite materials is presented. The focus of this review is the modification of natural fibres and its effect on fibre-matrix interfacial adhesion and properties. In addition, the effect of chemical treatment on fibre composition and fibre-matrix interfacial bonding mechanism are discussed.

  • 9.
    Alawode, Abiodun
    et al.
    Stellenbosch University, South Africa.
    Amiandamhen, Stephen
    Stellenbosch University, South Africa.
    Joubert, Lydia-Marie
    Stellenbosch University, South Africa.
    Meincken, Martina
    Stellenbosch University, South Africa.
    Tyhoda, Luvuyo
    Stellenbosch University, South Africa.
    Performance evaluation of a natural based adhesive derived from Irvingia wood species kernel extracts on wood panel production2020Inngår i: Journal of Adhesion Science and Technology, ISSN 0169-4243, E-ISSN 1568-5616, Vol. 34, nr 9, s. 995-1012Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Irvingia seed kernels have been identified as potential raw materials for a wide range of applications such as biodiesel, cosmetics, perfume, and soap. As a result, the Irvingia wood species is earmarked for domestication globally in order to commercially exploit these potential benefits. This study investigated the physical and mechanical properties of experimental panels made with pine (Pinus elliottii) wood particles, using modified Irvingia gabonensis (IG) and Irvingia wombolu (IW) extracts as a binder. The mean values of modulus of rupture (MOR) and modulus of elasticity (MOE) for the panels produced with this Irvingia-based adhesive were 5.8 and 1251 MPa, respectively. These values are within the minimum requirement for MOR and MOE (5.5 and 1034 MPa, respectively) for panel grade 1-L-1 as specified by the American National Standards Institute A208.1. The results from the study show that Irvingia kernel extracts may be considered as a potential environmentally friendly adhesive for wood composite manufacture.

  • 10.
    Amiandamhen, Stephen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). University of Benin, Nigeria.
    Osadolor, Samson
    University of Tuscia, Italy;University of Benin, Nigeria.
    Recycled waste paper-cement composite panels reinforced with kenaf fibres: durability and mechanical properties2020Inngår i: Journal of Material Cycles and Waste Management, ISSN 1438-4957, E-ISSN 1611-8227, Vol. 22, nr 5, s. 1492-1500Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is a growing interest on recycling of waste fibres as an alternative to landfill disposal. The aim of the study was to investigate the durability and mechanical properties of waste paper-cement composite panels reinforced with varying kenaf fibre content (FC, 2-10%). The panels produced were evaluated for properties including modulus of rupture (MOR) and apparent modulus of elasticity (MOE). The resistance of the panels was tested in the field for both termite damage and fungi decay for a period of 24 weeks. Accelerated decay test was also performed on selected samples. The results showed that the mean MOR ranged from 3.17 MPa for samples with 10% FC to 4.84 MPa for samples with 8% FC. The mean MOE ranged from 248 MPa for samples with 10% FC to 1298.1 MPa for samples with 8% FC. Statistical analysis showed that the effect of the fibre content was significant on the properties evaluated (p<0.05). The study concluded that the optimum fibre content for improving strength and physical properties of paper-cement composites in a ratio of 1:1 (w/w) using kenaf as reinforcing fibre is 8%. The panels were highly resistant to both termite and fungi attack for the study duration.

  • 11.
    Kumar, Anuj
    et al.
    Natural Resources Institute Finland (Luke), Finland;Czech Technical University in Prague, Czech Republic.
    Ryparovà, Pavla
    Czech Technical University in Prague, Czech Republic.
    Kasal, Bohumil
    Wilhelm-Klauditz-Institut WKI, Germany.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Hajek, Petr
    Czech Technical University in Prague, Czech Republic.
    Resistance of bamboo scrimber against white-rot and brown-rot fungi2020Inngår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 15, nr 1, s. 57-63Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bamboo scrimber is one of the most emerging structural materials for future building applications andit possesses properties comparable to other natural wood-based engineered materials such as glulam,laminated veneer lumber and cross-laminated timber. The goal of this work was to study the decayresistance of bamboo scrimber against white-rot (Trametes versicolor) and brown-rot fungi (Serpulalacrymans). Bamboo scrimber samples were incubated in petri dishes with the wood-decaying fungiand the weight loss after 12 weeks was measured. The surface morphology of fungal-degradedbamboo scrimber was evaluated using optical microscopy. Based on the percentage weight loss,bamboo scrimber could be classified as highly resistant against bio-deterioration by white andbrown-rot fungi.

  • 12.
    Jiang, Wen
    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).
    Hosseinpourpia, Reza
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Linnéuniversitetet, Kunskapsmiljöer Linné, Avancerade material.
    Žigon, Jure
    University of Ljubljana, Slovenia.
    Petrič, Marko
    University of Ljubljana, Slovenia.
    Šernek, Milan
    University of Ljubljana, Slovenia.
    Medved, Sergej
    University of Ljubljana, Slovenia.
    Utilization of Partially Liquefied Bark for Production of Particleboards2020Inngår i: Applied Sciences, E-ISSN 2076-3417, Vol. 10, nr 15, s. 1-14, artikkel-id 5253Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bark as a sawmilling residue can be used for producing value-added chemicals and materials. This study investigated the use of partially liquefied bark (PLB) for producing particleboard with or without synthetic adhesives. Maritime pine (Pinus pinaster Ait.) bark was partially liquefied in the presence of ethylene glycol and sulfuric acid. Four types of particleboard panels were prepared with a PLB content of 4.7%, 9.1%, 20%, and 33.3%, respectively. Another five types of particleboard panels were manufactured by using similar amounts of PLB and 10 wt.% of melamine–urea–formaldehyde (MUF) adhesives. Characterization of bark and solid residues of PLB was performed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and automated vapor sorption (AVS). Mechanical and physical properties of the particleboard were tested according to the European standards EN 310 for determining modulus of elasticity and bending strength, EN 317 for determining thickness swelling after immersion in water, and EN 319 for determining internal bond strength. The results showed that the increase in PLB content improved the mechanical strength for the non-MUF boards, and the MUF-bonded boards with up to 20% of PLB met the requirements for interior uses in dry conditions according to EN 312. The non-MUF boards containing 33.3% of PLB and the MUF-bonded boards showed comparable thickness swelling and water absorption levels compared to the reference board.

    Fulltekst (pdf)
    fulltext
  • 13.
    Kumar, Anuj
    et al.
    Natural Resources Institute Finland (Luke), Finland.
    Ryparová, Pavla
    Czech Technical University in Prague, Czech Republic.
    Hosseinpourpia, Reza
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Linnéuniversitetet, Kunskapsmiljöer Linné, Avancerade material.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Prošek, Zdeněk
    Czech Technical University in Prague, Czech Republic.
    Žigone, Jure
    Czech Technical University in Prague, Czech Republic.
    Petrič, Marko
    University of Ljubljana, Slovenia.
    Hydrophobicity and resistance against microorganisms of heat and chemically crosslinked poly(vinyl alcohol) nanofibrous membranes2019Inngår i: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 360, s. 788-796Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Poly(vinyl alcohol) (PVA) is a water-soluble, semi-ionic and biocompatible polymer with excellent chemical and thermal stability. The chemical crosslinking of PVA membrane improve its stability towards humidity and water. In the present work, PVA nanofibrous membranes were fabricated using roller electrospinning techniques. The prepared membranes were crosslinked by heat treatment, glutaraldehyde dipping, and glutaraldehyde vapour. Furthermore, octadecyltrichlorosilane (OTS) treatment was used for hydrophobization of the crosslinked membranes. The prepared crosslinked membranes were analysed by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The hydrophobization of PVA nanofibrous membranes were analysed by employing optical goniometer and auto-dynamic vapour sorption (AVS) techniques. Further, the PVA membranes were tested against algae and mould growth at in-vitro laboratory conditions. The SEM and FTIR results revealed significant differences in the morphology of the PVA nanofibrous membranes and in chemical bond formation due to crosslinking treatments. Water contact angle and AVS data confirmed a hydrophobization of PVA membranes by the treatments.

  • 14.
    Mngomezulu, Lehlohonolo
    et al.
    Stellenbosch University, South Africa.
    Amiandamhen, Stephen
    Stellenbosch University, South Africa.
    Meincken, Martina
    Stellenbosch University, South Africa.
    Tyhoda, Luvuyo
    Stellenbosch University, South Africa.
    Influence of heat curing and aggregates on the properties of phosphate bonded biocomposites2019Inngår i: SN Applied Sciences, ISSN 2523-3963, E-ISSN 2523-3971, Vol. 1, s. 1-12, artikkel-id 1620Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is renewed effort in reducing the carbon footprint of conventional building materials by employing novel phosphate cements. This study investigates the influence of industrial aggregates, namely fly ash, silica fume and calcium carbonate on biocomposite properties. The biomaterials used included pine, bagasse and wattle. The density of the boards produced ranged from 0.82 to 1.16 g/cm3, and the MOE ranged from 410.57 to 1737.87 MPa. The study concluded that biomass type, curing temperature and aggregates have significant effects on the biocomposite properties. The boards produced met the physical property requirements for use as non-load-bearing structures in humid and external conditions.

  • 15. Olayiwola, Hamed
    et al.
    Amiandamhen, Stephen
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Stellenbosch University, South Africa.
    Meincken, Martina
    Stellenbosch University, South Africa.
    Tyhoda, Luvuyo
    Stellenbosch University, South Africa.
    Investigating the thermal and mechanical properties of fly ash/metakaolin-based geopolymer reinforced with alien invasive wood species2019Inngår i: Proceedings of the 2019 Society of Wood Science and Technology International Convention: Convention Theme: Renewable Materials and the Wood-based Bioeconomy, 2019, s. 241-241Konferansepaper (Fagfellevurdert)
  • 16.
    Jones, Grace
    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).
    Liziniewicz, Mateusz
    Swedish Forestry Research Institute, Sweden.
    Lindeberg, Johan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Nondestructive wood density testing in downy birch and silver birch genetics field trial, southern Sweden2019Inngår i: 21st International Nondestructive Testing and Evaluation of Wood Symposium,: Freiburg, Germany, 2019 / [ed] Wang, Xiping; Sauter, Udo H.; Ross, Robert J.,, U.S. Department of Agriculture (USDA) , 2019, s. 79-86Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Non-destructive testing of wood density, as is already done for Eucalyptus, can allow for earlyselection of birch trees for breeding programmes and stands for harvesting. In this work, external stemquality traits were visually assessed in a family trial of downy (Betula pendula) and silver (B.pubescens) birch in southern Sweden. A subsample of trees was measured for wood density using thePilodyn resistometer portable NDT tool. An X-ray microdensitometric analysis of the subsample oftrees was completed using the Itrax X-ray machine for increment cores taken from the south face,through the pith to the north bark at 1.3 m stem height. The Pearson’s r value for Itrax density andPilodyn density was high (0.580 for downy birch and 0.795 for silver birch), and this correlationmeans Pilodyn should provide a good estimate of average birch wood density. Neither species hadstable wood density values at age 13 and both species’ density increased over time from pith to bark.Ring width influence on stem density was minor or non-existant, and may vary between birch species

    Fulltekst (pdf)
    fulltext
  • 17.
    Amiandamhen, Stephen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Stellenbosch University, South Africa.
    Meincken, Martina
    Stellenbosch University, South Africa.
    Tyhoda, Luvuyo
    Stellenbosch University, South Africa.
    Phosphate bonded natural fibre composites: a state of the art assessment2019Inngår i: SN Applied Sciences, ISSN 2523-3963, E-ISSN 2523-3971, Vol. 1, nr 8, artikkel-id 910Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Over the last few decades, innovative wood composite products and processes have created markets for new and existing products. Inorganic bonded fibre composites have been developed for high performance applications using conventional cement and concrete. The demands for wood based composites along with increasing economic and environmental concerns on conventional wood products necessitate moving beyond the traditional processing methods to more cost-effective and environmentally friendly approaches. In the wake of the twenty-first century, a fast-setting phosphate binder with a low carbon footprint was developed, which can alternatively be utilized in wood composite development. This paper reviews the recent progress in phosphate bonded composite products, based on published literature from the last two decades. A brief background on Portland cement based natural fibre composites is presented. In addition, the mechanism of the formulation of phosphate binders, the effect of aggregates in the materials and the environmental benefits accruable to such materials are discussed.

    Fulltekst (pdf)
    Appl. Sci.
  • 18.
    van Blokland, Joran
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Olsson, Anders
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Oscarsson, Jan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Prediction of bending strength of thermally modified timber using high-resolution scanning of fibre direction2019Inngår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 77, nr 3, s. 327-340Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The market share of thermally modified wood (TMW) has increased in Europe during the past few years as an environmentally friendly and durable building product. However, TMW products of today are not permitted for use in structural applications, because the reduction in strength that is caused by thermal treatment cannot be accounted for. The purpose of this paper was to investigate the bending properties of thermally modified timber (TMT) of Norway spruce, and to explore possibilities to predict the bending properties of TMT. A sample of 100 boards from a 2X-log sawing pattern of 100 logs was thermally modified according to the ThermoWood® process, while the mirror 100 boards served as an unmodified control sample. Two non-destructive methods were employed: (1) a novel method based on scanning of fibre directions to obtain the lowest edgewise bending modulus of elasticity (MOE) along a board, and (2) a conventional excitation method to determine the first axial resonance frequency used to calculate the axial dynamic MOE. Finally, the boards were bent to failure according to European standard EN 408. Despite the fact that bending strength was reduced by 42% due to thermal treatment, the type and location of failure in TMT remained related to the presence of knots. Prediction of bending strength based on local fibre direction and axial dynamic MOE, gave coefficients of determination of 0.51 for the thermally modified boards and 0.69 for the control boards, whereas axial dynamic MOE alone gave 0.46 and 0.57, respectively. These results indicate that although Norway spruce TMT has lower bending strength compared to unmodified timber, predictions of the bending strength can be made with good accuracy.

    Fulltekst (pdf)
    fulltext
  • 19.
    Alawode, Abiodun
    et al.
    Stellenbosch University, South Africa.
    Eselem-Bungu, Paul
    Stellenbosch University, South Africa.
    Amiandamhen, Stephen
    Stellenbosch University, South Africa.
    Meincken, Martina
    Stellenbosch University, South Africa.
    Tyhoda, Luvuyo
    Stellenbosch University, South Africa.
    Properties and characteristics of novel formaldehyde-free wood adhesives prepared from Irvingia gabonensis and Irvingia wombolu seed kernel extracts2019Inngår i: International Journal of Adhesion and Adhesives, ISSN 0143-7496, E-ISSN 1879-0127, Vol. 95, artikkel-id 102423Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is renewed interest in the domestication of Irvingia tree species due to the potential use of various parts of the tree as raw materials for a wide range of applications such as biodiesel production, cosmetics, perfumes, soap, weight-loss supplement etc. The current study investigates the properties of extracts from the seed kernels of two Irvingia species – Irvingia gabonensis (IG) and Irvingia wombolu (IW) as natural wood adhesives. Three extraction methods using various solvent/solute media were compared in terms of yield, composition and mechanical properties. Statistically, the analysis revealed significant differences between the different extraction methods. The adhesion properties of the extracts were tested on wood veneers according to the American Society for Testing and Materials standard (ASTM D – 906-64). The shear strength of the extracts ranged from 0.55 to 1.5 MPa and 0.86 to 1.7 MPa for IG and IW, respectively. The initial decomposition temperature of all Irvingia Kernel extract ranges from 138.3 – 149.11 oC for IG and 129.5 – 145.3 oC for IW. As a result, the hot melt temperature for the adhesive experiments was set around 150 oC. The results indicate that Irvingia kernel extract is a more promising source of non-formaldehyde based adhesives in wood composite production.

  • 20. Alawode, Abiodun
    et al.
    Amiandamhen, Stephen
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Stellenbosch University, South Africa.
    Meincken, Martina
    Stellenbosch University, South Africa.
    Tyhoda, Luvuyo
    Stellenbosch University, South Africa.
    Properties and potential use of Irvingia gabonensis and Irvingia wombolu kernel extracts as an eco-friendly wood adhesive2019Inngår i: 73rd Forest Products Society International Convention, Atlanta, Georgia, USA, 25th – 28th June 2019, 2019Konferansepaper (Fagfellevurdert)
  • 21.
    Hosseinpourpia, Reza
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Linnéuniversitetet, Kunskapsmiljöer Linné, Avancerade material.
    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 adhesive2019Inngår i: Wood research, ISSN 1336-4561, Vol. 64, nr 2, s. 185-194Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 22.
    Hosseinpourpia, Reza
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Linnéuniversitetet, Kunskapsmiljöer Linné, Avancerade material.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Eceiza, Arantxa
    University of the Basque Country UPV/EHU, Spain.
    Thermal stability and water vapor sorption of wheat starch modified with isocyanate functional groups2019Inngår i: 7th International Conference on Biobased and Biodegradable Polymers (BIOPOL), 17-19th June 2019, Stockholm, Sweden, KTH , 2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Wheat starch polymer was modified through the unequal reactivity of isocyanate groups in isophorone diisocyanate (IPDI) monomer. Fourier transform infrared spectroscopy (FTIR) and 13C nuclear magnetic resonance (13C NMR) confirmed the presence of both urethane and isocyanate functionalities in the modified polymer. Thermal stability and water vapor sorption properties of the modified polymer were evaluated by means of thermogravimetric analysis (TGA) and auto-dynamic vapor sorption (AVS) method, respectively. The results indicated that the modified starch polymer showed a better thermal stability (e.g. higher temperature at maximum weight loss) compared to the unmodified one. Water vapor sorption of starch polymer was considerably reduced after modification with IPDI monomer.

    Fulltekst (pdf)
    fulltext
  • 23.
    Hosseinpourpia, Reza
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Linnéuniversitetet, Kunskapsmiljöer Linné, Avancerade material.
    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 fibers2019Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 136, nr 13, artikkel-id 47303Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 24.
    Adamopoulos, Stergios
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Ahmed, Sheikh Ali
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Lankveld, Chiel
    Accsys Group, Netherlands.
    Acoustic properties of acetylated wood under different humid conditions and its relevance for musical instruments2018Inngår i: Proceedings of the 9th European Conference on Wood Modification 2018, Arnhem, The Netherlands / [ed] Jos Creemers, Thomas Houben, Bôke Tjeerdsma, Holger Militz and Brigitte Junge, The Netherlands: Practicum , 2018, s. 236-243Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In musical instrument making, less expensive wood species and materials with good characteristics and acoustical properties can provide potentials to find alternatives to the traditional exotic wood species used today. Modified wood could be such a choice if shows similar sound characteristics to wood coming from endangered and expensive tropical species with problematic commercial availability. In musical instruments, the overall functionality depends on the contribution of wood to different material performance indexes like sound radiation coefficient (R), characteristic impedance (z) and acoustic conversion efficiency (ACE). In this study, the performance indexes were measured for acetylated beech, maple and radiata pine and compared with these obtained for the reference wood materials maple, mahogany, alder and ash. A non-destructive free-free flexural vibration test method was used at constant temperature (20oC) but in different humid conditions- dry (35% RH), standard (65% RH) and wet (85% RH). Dimensional changes in the different humid conditions were also taken in account. Acetylated wood showed lower EMC with higher dimensional stability at each humidity level as compared with the reference wood materials. These properties are considered important factors for making quality musical instruments. Based on the acoustical properties, acetylated wood materials, especially radiata pine, showed good potential for use for musical instruments where specific characteristics of sound are required. However, the other types of acetylated wood can also be used for specific musical instruments.

  • 25.
    Ahmed, Sheikh Ali
    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).
    Acoustic properties of modified wood under different humid conditions and their relevance for musical instruments2018Inngår i: Applied Acoustics, ISSN 0003-682X, Vol. 140, s. 92-99Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In musical instrument making, there is a strong need to find alternatives to the traditional endangered and expensive tropical wood species used today. The present study examined whether different commercial and experimental modified wood materials have the necessary acoustic qualities under different humid conditions (dry, standard and wet) to contribute to the use of raw materials for wooden musical instruments. The materials were thermally-modified wood (ash, aspen and birch), acetylated wood (beech, maple and radiata pine), melamine- and phenol formaldehyde-treated beech and furfurylated Scots pine (Kebony Scots pine). Investigations involved physical (density ρ, Equilibrium moisture content EMC, volumetric shrinkage) and dynamic elastic testing by a free-free flexural vibration method to determine various acoustic characteristics: specific dynamic modulus (MOEdyn/ρ), damping coefficient (tanδ), speed of sound (c), specific acoustic impedance (z), sound radiation coefficient (R) and acoustic conversion efficiency (ACE). The modified materials and especially acetylated wood showed low EMC values and high dimensional stability at each humidity level, which are considered important factors for making quality musical instruments. Based on the obtained value ranges of all acoustical properties, the different modified wood materials could find uses in musical instruments where specific characteristics of sound are required. Furthermore, most of the modified materials showed an excellent acoustic performance in the three humid conditions based on a high ACE and low tanδ. Furfurylated Scots pine and phenol formaldehyde-treated beech showed an inferior acoustic quality with the lowest ACE and the highest tanδ, which is a less favourable combination for most of the musical instruments.

  • 26.
    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 models2018Inngår 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. 87-92Konferansepaper (Fagfellevurdert)
    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.

  • 27.
    van Blokland, Joran
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Olsson, Anders
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Oscarsson, Jan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Bending properties and strain fields around knots in thermally modified timber2018Inngår i: / [ed] Jos Creemers, Thomas Houben, Bôke Tjeerdsma, Holger Militz and Brigitte Junge, 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

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

  • 28.
    Jiang, Wen
    et al.
    University of Eastern Finland, Finland.
    Tomppo, Laura
    University of Eastern Finland, Finland.
    Pakarinen, Timo
    Karelia University of Applied Sciences, Finland.
    Sirviö, Juho A.
    University of Oulu, Finland.
    Liimatainen, Henrikki
    University of Oulu, Finland.
    Haapala, Antti
    University of Eastern Finland, Finland.
    Effect of Cellulose Nanofibrils on the Bond Strength of Polyvinyl Acetate and Starch Adhesives for Wood2018Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 13, nr 2, s. 2283-2292Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nanocellulose is a competitive reinforcement material for usein biocomposite structures and fibrous products. In this study, adhesive mixtures of dicarboxylic acid cellulose nanofibrils (CNF) were dispersed into commercial polyvinyl acetate (PVAc) and starch adhesives, whichwere applied to Norway spruce (Picea abies) to assess their performance in wood joining. Single-lap joints were prepared and tested with PVAc mixtures with0 to 0.64 wt% CNFand starch glue mixtures containing 0 to 1.07 wt% CNF. CNF suspensionshaving three concentrations(0.64, 0.96,and 1.28%)were compared. The results showed that the optimum amount of CNF, 0.48% suspensions, added to PVAc increased the average lap joint strength (EN 205:2003) by 74.5% when compared to control specimens with pure PVAc. Correspondingly, 0.96% CNF suspensions also enhanced the strength of starch adhesive by 34.5%. Lower and higher CNF concentrations showed clearly inferior performance. (PDF) Effect of Cellulose Nanofibrils on the Bond Strength of Polyvinyl Acetate and Starch Adhesives for Wood

  • 29.
    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.) wood2018Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 13, nr 1, s. 331-345Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 30.
    Hemmilä, Venla
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Zabka, Michal
    IKEA of Sweden, 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 particleboards2018Inngår i: Advances in Materials Science and Engineering, ISSN 1687-8434, E-ISSN 1687-8442, artikkel-id 4582383Artikkel i tidsskrift (Fagfellevurdert)
    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

  • 31.
    van Blokland, Joran
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Olsson, Anders
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Oscarsson, Jan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Källander, Björn
    Swedish Wood, Sweden.
    Evaluation of non-destructive test methods to predict bending properties of thermally modified timber2018Inngår i: 2018 World Conference on Timber Engineering (WCTE), August 20-23, 2018, Seoul, Republic of Korea, World Conference on Timber Engineering (WCTE) , 2018, s. 8-Konferansepaper (Fagfellevurdert)
    Abstract [en]

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

  • 32.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Group of Forest Products2018Inngår i: Presented at Symposium "Perspectives in Renewables", 4-5 June 2018, BOKU Vienna, Austria, 2018Konferansepaper (Annet vitenskapelig)
  • 33.
    Altgen, Michael
    et al.
    Aalto Univ, Finland.
    Willems, Wim
    FirmoLin Technol BV, Netherlands.
    Hosseinpourpia, Reza
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Rautkari, Lauri
    Aalto Univ, Finland.
    Hydroxyl accessibility and dimensional changes of Scots pine sapwood affected by alterations in the cell wall ultrastructure during heattreatment2018Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 152, s. 244-252Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is a complex link between the water sorption behavior and the presence of accessible hydroxyl groups in the wood cell wall, which can be altered by heat-treatment (HT). This study analyses the effect of changes in the cell wall ultrastructure caused by two HT techniques on the hydroxyl accessibility, water vapor sorption and dimensional changes of Scots pine (Pinus sylvestris L.) sapwood. HT of wood in pressurized hot water at 120-170 °C was applied to cause the preferential bond cleavage, whereas HT of wood in oven-dry state in superheated steam at 180-240 °C was performed to create additional covalent cross-links within the cell wall matrix. Removal of cell wall polymers by HT and water leaching reduced the oven-dry dimensions of wood and enhanced the cellulose aggregation during drying. Cellulose aggregation restricted the cell wall shrinkage in circumferential direction, resulting in inhomogeneous shrinkage of the cell wall with only little changes in lumen volume by HT. Cellulose aggregation also reduced the water-saturated dimensions, but a decrease in swelling was only achieved when additional cross-links were formed by HT in dry state. Additional cross-links in the cell wall matrix also resulted in an additional reduction in water sorption at 25 °C and 93% RH. However, this was not caused by a further reduction in the hydroxyl accessibility. Instead, cross-linking was shown to reduce the amount of accessible OH groups that are simultaneously active in sorption, which was explained based on the concept of sorption of water dimers at hydroxyl group pairs at high RH levels.

  • 34.
    Jiang, Wen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Kumar, Anuj
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Natural Resources Institute Finland (Luke), Finland.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Liquefaction of lignocellulosic materials and its applications in wood adhesives — A review2018Inngår i: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 124, s. 325-342Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Liquefaction, a useful method of turning whole biomass into liquids, provides advantages for energy andpolymers and finds applications in many sectors. This paper reviews the different liquefaction technologies andrecent advances in the development of sustainable wood adhesives. Current liquefaction technologies includehydrothermal liquefaction (HTL) and moderate acid-catalyzed liquefaction (MACL). HTL produces bio-oils asprimary products, and solid residues and gases as by-products. MACL depends on the solvent types used, whichare grouped to polyhydric alcohols and phenols. Bio-polyols from alcohol liquefaction, phenolated biomass fromphenol liquefaction and phenolic compounds rich-HTL bio-oils have been used in the production of liquefiedbiomass-based adhesives, which have shown competitive properties but face challenges for industrial uses. Yet, abetter understanding of reaction pathways and optimization of the liquefaction processes is needed.

  • 35.
    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 Groups2018Inngår i: Polymers, E-ISSN 2073-4360, Vol. 10, nr 9, artikkel-id 939Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 36. Alawode, Abiodun
    et al.
    Amiandamhen, Stephen
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Stellenbosch University, South Africa.
    Meincken, Martina
    Stellenbosch University, South Africa.
    Tyhoda, Luvuyo
    Stellenbosch University, South Africa.
    Performance evaluation of a natural based adhesive derived from Irvingia kernel extracts on wood panel production2018Inngår i: 3rd International Conference on Composites, Biocomposites and Nanocomposites, Port Elizabeth, South Africa, 7th – 9th November 2018, 2018Konferansepaper (Fagfellevurdert)
  • 37.
    Amiandamhen, Stephen
    et al.
    Stellenbosch University, South Africa.
    Montecuccoli, Zeno
    Stellenbosch University, South Africa.
    Meincken, Martina
    Stellenbosch University, South Africa.
    Barbu, Marius
    Stellenbosch University, South Africa.
    Tyhoda, Luvuyo
    Stellenbosch University, South Africa.
    Phosphate bonded wood composite products from invasive Acacia trees occurring on the Cape Coastal plains of South Africa2018Inngår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 76, nr 2, s. 437-444Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The feasibility of manufacturing phosphatebonded wood composite board products from four locallyoccurring invasive acacia tree species (Acacia cyclops, A.saligna, A. mearnsii and A. longifolia) was studied usinga formulated magnesium oxide (MgO) and monopotassiumphosphate (KH2PO4) binder system. The optimizationfor the manufacturing process was studied using a centralcomposite statistical design, whereupon the following factorswere considered, i.e. KH2PO4:MgO ratio, the fly ashcontent as partial replacement for the binder and the woodcontent as a ratio of wood to the total inorganic content.A fitted response surface plot was used to show the effectof the main factors and their interactions on the measuredboard properties. A response surface model was developedto predict the parameters leading to the best board properties.All physical properties evaluated met or exceededthe minimum requirements for low density particleboards.The results showed that the variables considered have significanteffects on the physical properties of the boards.The optimum composite manufacturing process for makingdurable products within the scope of the studied specieswas found to be a KH2PO4/MgO ratio of 1.66, an ashcontent of 2.7% and a wood/inorganic ratio of 0.96 for theselected wood species.

  • 38.
    Kumar, Anuj
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Czech Technical University in Prague, Czech Republic.
    Richter, Jan
    Czech Technical University in Prague, Czech Republic.
    Tywoniak, Jan
    Czech Technical University in Prague, Czech Republic.
    Hajek, Petr
    Czech Technical University in Prague, Czech Republic.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Šegedin, Urban
    University of Ljublijana, Slovenia.
    Marko, Petrič
    University of Ljublijana, Slovenia.
    Surface modification of Norway spruce wood by octadecyltrichlorosilane (OTS) nanosol by dipping and water vapour diffusion properties of the OTS-modified wood2018Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, nr 1, s. 45-56Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present research deals with a simple dipping method to insert octadecyltrichlorosilane (OTS) into cell walls of spruce wood and to deposit OTS layers on its inner and outer surfaces. Distribution and chemical interactions of OTS with wood polymers has been investigated by scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The OTS/n-hexane solution penetrated into wood via capillary forces through ray tracheids and bordered pits and was deposited as OTS organic-inorganic layers on wood cell walls. The hypothesis is supported by the results, according to which the OTS molecules are hydrolysed by the wood moisture and by free OH groups of the cell wall components. The hydrolysed OTS molecules react with the OH groups and elevate the hydrophobicity of wood.

  • 39.
    Amiandamhen, Stephen
    et al.
    Stellenbosch University, South Africa.
    Meincken, Martina
    Stellenbosch University, South Africa.
    Tyhoda, Luvuyo
    Stellenbosch University, South Africa.
    The effect of chemical treatments of natural fibres on the properties of phosphate‑bonded composite products2018Inngår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 52, nr 3, s. 653-675Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Phosphate-bonded composites are an emerging class of building materials produced from natural fibres and phosphate based cement pastes. They are durable and possess mechanical properties similar to those of Portland cement. However, the moisture absorption of natural fibre can lead to swelling which may result in the reduction in the mechanical strength properties and eventually negatively affect the long-term performance and dimensional stability of the products. This study was aimed at the modification of some properties of selected biomaterial residues in order to enhance the final properties of the phosphate-bonded composite product. Three different treatments were evaluated viz. 1% caustic alkali, 1% acetic anhydride and hot water on natural fibres derived from slash pine, black wattle and bagasse. The effect of the treatment on the fibres was evaluated via HPLC, SEM and FTIR. Further, the performance of the treated fibres was evaluated in composite panels bonded with magnesium phosphate (MgPO4) and calcium phosphate (CaPO4) cement pastes against the controls. The manufactured panels were tested for flexural properties and dimensional stability. In the MgPO4-bonded panels, the MOR increased from 0.55 MPa for untreated bagasse panels to 0.79 MPa for alkalised panels. Similarly, the MOE increased from 150.04 MPa for untreated bagasse panels to 175.65 MPa for alkalised panels. In untreated MgPO4-bonded panels, the mean density was 0.76, 078 and 0.75 g/cm3, while in alkalised panels, the mean density was 0.81, 0.81 and 0.81 g/cm3 for wattle, pine and bagasse panels, respectively. In the bagasse panels, the water absorption was 54.61% for untreated, 48.74% for hot water extracted, 42.21% for acetylated and 36.44% for alkalised MgPO4-bonded panels. This represents a percentage improvement of 11, 23 and 33%, respectively. Alkali-treated fibres had the best effect overall for all measured properties.

  • 40.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Utilisation of renewable biomass and waste materials in furniture and construction composites2018Konferansepaper (Annet vitenskapelig)
  • 41.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Wood variation and properties for industrial use2018Inngår i: Presented at FRAS workshop “Varierat skogsbruk  - hur påverkar olika skötselstrategier framtidens träprodukter?", 2018Konferansepaper (Annet (populærvitenskap, debatt, mm))
  • 42.
    Amiandamhen, Stephen
    et al.
    Stellenbosch University, South Africa.
    Meincken, Martina
    Stellenbosch University, South Africa.
    Tyhoda, Luvuyo
    Stellenbosch University, South Africa.
    Calcium phosphate bonded wood and fiber composite panels: production and optimization of panel properties2017Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 71, nr 9, s. 725-732Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The development of phosphate bonded composites with properties comparable with those of current Portland cement bonded products has been investigated. More precisely, the focus of the study was the optimization of calcium phosphate cements in combination with wood processing residues slash pine (Pinus elliottii Engelm.) planer shavings, Black wattle (Acacia mearnsii De Wild.) residues, Blue gum (Eucalyptus globulus Labill.) residues, hemp (Cannabis Sativa L.) hurds and dried crushed sugarcane bagasse (Saccharum officinarum L.) as well as pulp mill sludge and waste paper. A central composite design (CCD) for the response surface methodology (RSM) was applied for selection of the proper parameters. Mechanical tests were conducted on the composite products and the effect of the processing variables was evaluated based on the Pareto analysis of variance. The density of the wood-based panels ranged from 0.68 to 1.21 g cm−3, that of the agricultural fibers from 0.59 to 1.15 g cm−3 and that of the paper pulp panels from 0.81 to 1.21 g cm−3. The modulus of elasticity (MOE) data of the panels ranged from 1.63 to 4.92 MPa for wood, from 0.37 to 3.28 MPa for agricultural fibers and from 0.65 to 3.87 MPa for paper-pulp-based fibers. The physical properties of the composite products met the requirements for Portland-cement-bonded particleboards (EN 634-2, 2007).

  • 43.
    Cristina, Simón
    et al.
    Technical University of Madrid, Spain.
    Francisco, García Fernández
    Technical University of Madrid, Spain.
    Luis, García Esteban
    Technical University of Madrid, Spain.
    Paloma, de Palacios
    Technical University of Madrid, Spain.
    Hosseinpourpia, Reza
    University of Göttingen, Germany.
    Carsten, Mai
    University of Göttingen, Germany.
    Comparison of the saturated salt and dynamic vapor sorption methods in obtaining the sorption properties of Pinus pinea L.2017Inngår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 75, nr 6, s. 919-926Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Several methods are available for obtaining the sorption isotherms of wood. Among these, the saturated salt and dynamic vapor sorption methods are the most frequently used  ones. For the first time, the hygroscopic response of wood obtained using these two methods is compared. This is done by determining the 35 and 50°C adsorption isotherms of juvenile and mature wood of Pinus pinea L. The hygroscopic behavior of the two types of wood is different, as the mature wood has a higher moisture content than the juvenile wood in the isotherms studied. Comparison of the static saturated salt method and dynamic vapor sorption shows few significant differences between the equilibrium moisture content obtained by each method during the adsorption process, both in a point by point comparison and in the comparison of quadratic polynomial forms of the Guggenheim Anderson-de Boer model. Moreover, in both methods the point of relative humidity from which multilayer sorption predominates over monolayer sorption is similar.

  • 44.
    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
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Georg August University Göttingen, Germany.
    Correlation between gas and liquid permeability with noise reduction coefficient in insulation boards made from sugar cane bagasse2017Inngår i: Bulgarian Journal of Agricultural Science, ISSN 1310-0351, Vol. 23, nr 3, s. 674-681Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 45.
    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 review2017Inngår i: RSC Advances, E-ISSN 2046-2069, Vol. 7, nr 61, s. 38604-38630Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 46.
    Funk, Monika
    et al.
    University of Göttingen, Germany.
    Wimmer, Rupert
    Universität für Bodenkultur Vienna, Austria.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Diotomaceous earth as an inorganic additive to reduce formaldehyde emmissions from particleboards2017Inngår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 12, nr 2, s. 92-97Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The presented research is about the use of a new type of a functional inorganic additive in particleboards, for the purpose of reducing free formaldehyde releases. One-layered particleboards were prepared in the laboratory by mixing industrial wood particles and urea-formaldehyde resin. Natural, abundantly and cheaply available nano-mesoporous diatomaceous earth (DE) was used, without and in combination with urea as a scavenger. Silica quartz sand was also added as a nonporous analogy. Particleboards were pressed at two press factors (9 and 15 s/mm). Formaldehyde release was determined using the rapid 3-hour-flask method (DIN EN 717-3). As a result, DE additions insignificantly reduced bending properties of particleboards. Internal bonding was in part significantly lowered. The particleboard produced with 3% urea loaded on 5% DE prior to application almost halved (–45%) the formaldehyde release. Formaldehyde release was on the average 17% lower when pressed at 15 s/mm instead of 9 s/mm. By loading urea onto the nano-mesoporous structure of DE, an improved scavenging function of urea could be shown.

  • 47.
    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 acid2017Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 138, s. 161-168Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 48.
    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 Fibreboards2017Inngår 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. 153-158Konferansepaper (Fagfellevurdert)
    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.   

    Fulltekst (pdf)
    fulltext
  • 49.
    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 wood2017Inngår i: IUFRO Division 5 Conference, 12-14 June, 2017 - Vancouver, British Columbia: Final program, proceedings and abstracts, IUFRO Division 5 Conference , 2017Konferansepaper (Fagfellevurdert)
    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.

  • 50.
    Ahmed, Sheikh Ali
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Morén, Tom
    Luleå University of Technology.
    Sehlstedt-Persson, Margot
    Luleå University of Technology.
    Blom, Åsa
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Effect of oil impregnation on water repellency, dimensional stability and mold susceptibility of thermally-modified European aspen and downy birch wood2017Inngår i: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 63, nr 1, s. 74-82Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

123 1 - 50 of 123
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf