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Schwarzbauer P.,University of Vienna | Stern T.,Kompetenzzentrum Holz GmbH Wood K plus
Forest Policy and Economics | Year: 2010

In this paper, a simulation model of the Austrian forest-based sector (FOHOW) was used to assess the effects of increasing wood utilization for energy production on the Austrian forest-based sector. In order to reflect the political targets regarding the use of renewable energy a "wood-for-energy" scenario was developed and compared with a "business-as-usual" base-scenario up to the year 2020. The analysis shows that the rising fuelwood demand in the "wood-for-energy" scenario would clearly lead to a much stronger competition for small roundwood (pulpwood) and sawmill residues. Compared to the base scenario, this competition would increase pulpwood prices and - to some extent - forest product prices (especially sawmill residues and pulp). In general, forestry and sawmills would be the winners, the panel and paper industries would be the losers of a "wood-for-energy" policy. The panel and paper industries would face decreased gross profits, because of two developments happening at the same time: a decrease in production and an increase in costs (roundwood and sawmill residues) beyond the increase of forest products prices. The analysis also reveals that the additional demand for fuelwood could only be met by an additional supply from the Austrian forests - if the fuelwood price was attractive enough (by 2020 more than 50% higher than in the base-scenario) for the forest owners. © 2009 Elsevier B.V. All rights reserved.


Widsten P.,Scion Research | Heathcote C.,Kompetenzzentrum Holz GmbH Wood Kplus | Kandelbauer A.,University of Natural Resources and Life Sciences, Vienna | Kandelbauer A.,Reutlingen University | And 4 more authors.
Process Biochemistry | Year: 2010

Grafting natural antibacterial phenols onto lignocellulosic materials is an environmentally friendly way of imparting antibacterial properties to the substrates. In the present investigation, wood veneer and pulp were treated with tannins in the presence or absence of laccase. Treatments with hydrolysable tannins significantly improved the antibacterial resistance of veneers and paper made from tannin-treated pulp against a Gram-positive bacterium (Staphylococcus aureus) while a more modest protective effect was observed against a Gram-negative bacterium (Escherichia coli). Condensed tannin improved the antibacterial resistance against S. aureus, albeit less than hydrolysable tannin, but had little effect on E. coli. A cationic condensed tannin derivative bearing a quaternary amino group provided far better resistance to pulp against S. aureus and E. coli than the corresponding unmodified condensed tannin. These findings agree with the minimal inhibitory concentrations (MICs) of the tannins and their reactivities toward laccase as determined by O2 consumption measurements. Due to a better retention of tannins via covalent bonding, treatments with laccase usually resulted in greater antibacterial effects than those without laccase. LC-MS investigations with monomeric tannin and lignin model compounds showed that covalent bonding of tannin to lignin via radical coupling occurred in the presence of laccase. © 2010 Elsevier Ltd.


Schwarzbauer P.,University of Natural Resources and Life Sciences, Vienna | Schwarzbauer P.,Kompetenzzentrum Holz GmbH Wood K plus | Weinfurter S.,University of Natural Resources and Life Sciences, Vienna | Stern T.,Kompetenzzentrum Holz GmbH Wood K plus | Koch S.,Kompetenzzentrum Holz GmbH Wood K plus
Forest Policy and Economics | Year: 2013

In light of the recent economic crisis, the authors have assessed the effects of different types of economic crises' scenarios on the Austrian forest-based sector using a simulation model (FOHOW) written in the System-Dynamics (SD) language. The model addresses the interactions between the general economy and the forest sector, including forestry, forestry-based industries and energy. The simulation period for all of the scenarios ranged from 2006 to 2025. As compared to the past, the development of the sector substantially changes, even in the base scenario. These changes are primarily caused by increased demand for wooden biomass for energy due to the assumed execution of the National Action Plan for Renewable Energy. All crises' scenarios resulted in declining production and lower prices compared to the base scenario, differing only in magnitude. Forestry, sawmill and paper industries perform better in an export crisis than in a local crisis, because decreased exports can, to a certain extent, be compensated for by increasing domestic demand, while the domestic shortfalls are difficult to compensate by raising exports. By contrast, the export-oriented panel industry does better in a local crisis simulation. In general, economic crises only moderately change the assortment composition of timber supply within the forestry industry. The results also show that the sawmill industry plays a vital role in the allocation of wooden biomass in all of the scenarios. When developing policies for forest-based industries, specifically the procurement of wooden raw material, the key role of the sawmill industry must be considered in each case. © 2012 Elsevier B.V.


Unterweger C.,Kompetenzzentrum Holz GmbH Wood K Plus | Bruggemann O.,Johannes Kepler University | Furst C.,Kompetenzzentrum Holz GmbH Wood K Plus
Polymer Composites | Year: 2014

Among the synthetic fibers, glass fibers (GF) are most widely used in thermoplastic short-fiber-reinforced polymers (SFRP), as they offer good strength and stiffness, impact resistance, chemical resistance, and thermal stability at a low price. Carbon fibers (CF) are applied instead of GF, when highest stiffness is required. Other types of synthetic fibers like aramid (AF), basalt (BF), polyacrylonitrile (PAN-F), polyethylene terephthalate (PET-F), or polypropylene fibers (PP-F) are rarely used in SFRP, although they offer some advantages compared with GF. The aim of this article is, to give an overview of various fiber types with regard to their mechanical properties, densities, and prices as well as the performance of their thermoplastic composites. The mechanical properties are presented as Ashby plots of tensile strength versus tensile modulus, both in absolute and specific (absolute value divided by density) values. This overview also focuses on modification of fiber/matrix interaction, as interfacial adhesion has a huge impact on composite performance. A summary of established methods for characterization of fibers, polymers, and composites completes this article. POLYM. COMPOS., 35:227-236, 2014. © 2013 Society of Plastics Engineers.


Leitner J.,Mondi Frantschach GmbH | Zuckerstatter G.,Kompetenzzentrum Holz GmbH Wood Kplus | Schmied F.,University of Leoben | Schmied F.,University of Graz | Kandelbauer A.,Reutlingen University
European Journal of Wood and Wood Products | Year: 2013

The effects of heating lab cooked never dried kraft pulp from pine and spruce at 5 % consistency to 80, 100 and 120 C in a pressurized vessel were evaluated based on various fiber and sheet properties. The settings of pH and conductivity in the lab trial were chosen in accordance with operations such as oxygen delignification, alkaline extraction, washing or storage of pulp in an integrated paper mill. It was found that the tensile strength was reduced steadily with increasing temperature. Nuclear magnetic resonance spectroscopy showed that fiber crystallinity and pore size increased at high temperatures compared to the unheated reference. Crystallinity most likely affected the fiber flexibility and thus resulted in less and weaker fiber-fiber bonds. Atomic force microscopy indicated that the amount of precipitated lignin granules on the fiber surface was reduced with increasing temperature. The roughness of the fiber surface did not significantly change with temperature and hence did not negatively influence the tensile strength. It was remarkable that a so called reversed latency was observed. Instead of a decrease in fiber curl with temperature, the fiber became significantly more curled. A large portion of the losses in tensile strength was attributed to the increase in fiber curl and leaching of hemicelluloses from the fiber wall. © 2012 Springer-Verlag Berlin Heidelberg.


Stoeckel F.,Kompetenzzentrum Holz GmbH Wood K Plus | Stoeckel F.,TU Braunschweig | Konnerth J.,University of Natural Resources and Life Sciences, Vienna | Gindl-Altmutter W.,Kompetenzzentrum Holz GmbH Wood K Plus | Gindl-Altmutter W.,University of Natural Resources and Life Sciences, Vienna
International Journal of Adhesion and Adhesives | Year: 2013

In this review the current state of the art on mechanical properties of pure wood adhesives is summarised and discussed. Conventionally, mechanical adhesive properties were characterised by means of macroscopic tensile or bending tests of ex-situ cured adhesive films. More recently, nanoindentation was also used to characterise such ex-situ specimens, but more importantly, this method allows the mechanical characterisation of adhesive bond lines in-situ. Mechanical tests reveal high variability between, but notably also within specific groups of adhesives. For example, the modulus of elasticity covers a wide range of more than two magnitudes ranging from 0.1 GPa up to 15 GPa. Significant differences in adhesive stiffness were observed for adhesives intended to be used for solid wood products compared to wood based composite adhesives, the latter showing higher modulus values. In addition to mechanical adhesive properties as such, factors possibly influencing adhesive performance such as temperature, humidity or ageing of the bonds are taken into consideration. © 2013 Elsevier Ltd.


Muller U.,Kompetenzzentrum Holz GmbH Wood K Plus | Steiner M.,Kompetenzzentrum Holz GmbH Wood K Plus
European Journal of Wood and Wood Products | Year: 2010

Photo-yellowing of native and polyethylene glycol (PEG) modified wood and wood/melamine resin composites was studied by means of FTIR-ATR technique and colourimetry (CIE L *a *b * method). The discolouration Δ E shows a systematic asymptotic trend towards higher values with increasing irradiation time. Yellowing proceeds faster in natural wood compared to wood/melamine resin composites. Nevertheless, long-term irradiation experiments show that the total colour shift is similar for both. Discolouration is significantly reduced by PEG treatment. In comparison to untreated wood, both glycol and melamine resin mainly reduce the irradiation-induced yellow shift. Moreover, PEG also shows an effect on the redness shift. Both effects result in decreased yellowing of the composite surface. An influence of the molecular weight of PEG was detected. © 2009 Springer-Verlag Zusammenfassung.


Unterweger C.,Kompetenzzentrum Holz GmbH Wood K plus | Duchoslav J.,Kompetenzzentrum Holz GmbH Wood K plus | Duchoslav J.,Johannes Kepler University | Stifter D.,Johannes Kepler University | Furst C.,Kompetenzzentrum Holz GmbH Wood K plus
Composites Science and Technology | Year: 2015

The aim of this paper is to evaluate the influence of carbon fibers (CF) surface properties and the amount of a coupling agent on the mechanical properties of injection molded CF reinforced polypropylene (PP) composites. Five types of CF, three sized, a de-sized and a de-sized and afterwards plasma-treated type, were characterized by X-ray photoelectron spectroscopy (XPS) and contact angle measurements. All fiber types were mixed with PP and various amounts of maleic anhydride grafted PP as coupling agent. Subsequently, all compounds were injection molded and characterized by measurement of flexural/tensile strength and modulus, notched/unnotched impact resistance, heat deflection temperature and fiber length. In addition fracture surfaces were analyzed by means of scanning electron microscopy (SEM).Both, contact angle measurements and XPS, showed, in good agreement, key differences in surface properties between the five CF samples. Mechanical testing and SEM images of fracture surfaces proved that fiber surface properties and the amount of coupling agent have major impacts on fiber/matrix interaction, hence on mechanical composite performance. © 2015 Elsevier Ltd.


Rauhala T.,Aalto University | King A.W.T.,University of Helsinki | Zuckerstatter G.,Kompetenzzentrum Holz GmbH Wood K plus | Suuronen S.,Aalto University | Sixta H.,Aalto University
Nordic Pulp and Paper Research Journal | Year: 2011

The first aim of this study was to investigate the delignification kinetics of alkaline cooking for autohydrolyzed birch wood (Betula pendula). A series of cooking trials, at temperatures ranging between 130°C and 170°C were performed on untreated (P-factor 0) and autohydrolyzed (P-factor 200) wood. The results of carbohydrate and lignin analyses were fitted to a kinetic model and it was observed that autohydrolysis doubles the delignification rate, during bulk delignification. However, a slight decrease was noticed in the delignification rate during residual pulping. Thus, the second aim of this study was to elucidate the reasons behind accelerated delignification. For this purpose two different autohydrolysis treatments (P-factors 200 and 750) were applied to birch wood. Lignin was isolated from both the native and autohydrolyzed wood and subjected to elemental analysis, methoxyl group determination, carbohydrate analysis and quantitative 1H, 13C and 31P nuclear magnetic resonance (NMR) spectroscopy. The results indicate that, during autohydrolysis, P-O-4 linkages were cleaved, the methoxyl group content was reduced and the syringyl/guaiacyl (S/G) ratio decreased. In addition, a decrease in primary and secondary aliphatic hydroxyl groups and an increase in phenolic hydroxyl groups were detected. It could be concluded that condensation reactions were also occurring during autohydrolysis. Although lignin reactions such as the cleavage of (i-O-4-cleavages and the increase in phenolic hydroxyl groups partly account for the pulping behaviour the reason behind the significantly accelerated bulk delignification is not entirely explained through this study. More research concerning reactions during autohydrolysis is needed.


Unterweger C.,Kompetenzzentrum Holz GmbH Wood K plus | Bruggemann O.,Johannes Kepler University | Furst C.,Kompetenzzentrum Holz GmbH Wood K plus
Composites Science and Technology | Year: 2014

The aim of this paper is to give a comprehensive overview of the effects of different fiber types on the properties (flexural/tensile strength and modulus, notched and unnotched impact resistance, heat deflection temperature, density) of injection molded short fiber-reinforced polypropylene composites. The fiber length in the composite materials was analyzed, too. The influence of a coupling agent on the fiber/matrix interaction respectively the composite performance was investigated. Different sizings are compared for most fiber types. All fibers were characterized by contact angle measurements and their respective surface energies were calculated.Most fiber types used show a reinforcing effect in accordance to the respective fiber properties. Comparison of different sizings and the use of a coupling agent show that fiber/matrix interaction has a significant impact on composite properties. A slight increase of the final fiber length can be achieved by using initially longer fibers. However, the results of this study indicate that a certain amount of adhesion is required for improving composite performance by increased fiber length. © 2014 Elsevier Ltd.

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