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VOLUME 53, ISSUE 1/2012

Selected mechanical properties of Turkey Oak (Quercus cerris L.)

Language: German
Pages: 5 - 10
Authors: Gernot Standfest, Thomas Wimmer, Agron Bajraktari, Thomas Schnabel, Alexander Petutschnigg

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Turkey Oak is one of the most widely used wood species in the Republic of Kosovo. As the use of wood is mainly concentrated on energy fuel, the potential for the use of this wood species as a construction material should be demonstrated. In this work, important mechanical properties of Turkey oak were studied and compared to white oak. The results of this study should demonstrate the possibilities of this wood species to develop new applications for it. The data gained serve as valuable tools to assist decision making in relation to the practical importance of Turkey Oak in the industry.

Investigations on properties of bog oak

Language: German
Pages: 11 - 17
Authors: Katalin Kránitz, Erik Baradit, Ewa Dobrowolska, Michael Plötze, Peter Niemz

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Physical-mechanical investigations on bog oak samples (Quercus robur L.), which were cut from a stored log in the river Bug (Poland), were carried out. Lifetime of the log is 150 years. It was found under a 3 m thick layer of sand and slush in the soil, where it has been stored for 7100 ± 50 years. In contrast to the very dark (deep black) discolouration in the outer zone, the wood became lighter in direction to the pith. No essential changes in mechanical as well as sorption behaviour compared to recent wood were determined. In radial direction the swelling of the bog oak decreased towards to the outer zone, that correlates with the colour changes. The darker the wood, the lower the radial swelling. In tangential direction only a slight influence of the position in the trunk could be seen. The porosity was unchanged. Regarding the mechanical properties the known differentiation of the E- and G-Modulus in the principal axes was determined. Measurements with ultrasound and the device BP5 (frequency 50 kHz) showed a little reduction of the dynamic E-Modulus. The E-Modulus of the bog oak decrease particularly with increasing dark colouration

Attractiveness of different qualities of constructional timber to males of the house longhorn beetle Hylotrupes bajulus (L.) (Coleoptera: Cerambycidae)

Language: German
Pages: 18 - 23
Authors: Christiane Ueckerdt, Rudy Plarre, Horst Hertel

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When searching for suitable sites for mating and breeding males of the house longhorn beetle discriminate properties of different timbers. Complete development of larvae is only possible in coniferous wood and this type of timber is highly attractive to males of this species. Quality differences of six timbers used for constructions were tested for their attractiveness to males of H. bajulus in behavioural bioassays. Tested timber qualities were kiln dried solid construction timber of pine and spruce, kiln dried laminated solid construction timber of pine, conventional dried and air dried pine wood as well as beech wood. The results showed a relative order of preferences by male house longhorn beetles for different qualities. Soft woods were always significantly preferred over hard wood. Among the soft wood qualities kiln dried pine was most attractive. Results indicate that the process of kiln drying does not enhance durability against infestation by H. bajulus.

Improvement of the gluability of wood polymer composites (WPC) by surface treatment; Part 2: Investigations on the fastness improvement of glued bonds

Language: German
Pages: 24 - 28
Authors: Mario Beyer, Klaus Vogelsang, Rico Emmler

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The effect of different physicochemical pre-treatment methods onto the adhesive bonding of polyolefine based WPC was studied. Besides WPC, other bonding partners were tested. The flame or the plasma treatment, both either with or without silane doping, as well as the gas phase fluorination were applied for their surface preparation. It was shown that the investigated techniques without exception lead to an improvement of the bonding fastness at all of the investigated materials, whilst the strongest increase was obtained with the fluorination technique. However, flaming was evaluated to be sufficiently effective in terms of applicability and process expense.

Finite Element Analysis of wood based on CT-data

Language: German
Pages: 29 - 34
Authors: Karl Entacher, Martin Öttl, Alexander Petutschnigg, Reinhard Bauer

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The present article describes a procedure to generate volume meshes for Finite Element (FE) Analysis from CT scanned wood samples. At the beginning of the chosen procedure Otsu threshold segmentation is used to generate a Label Map containing early and late wood layers. With a subsequent Discretized Marching Cubes algorithm, surface meshes are extracted. After smoothing and decimation of the triangles, volume meshes are generated in different ways. These volume meshes are used for bending test simulations in a commercial FE solver.

Fundamental investigation for the application of dielectric analysis as cross-linking control for aminoplast resins

Language: German
Pages: 35 - 40
Authors: Claudia Pretschuh, René Eckmann, Uwe Müller, Clemens Schwarzinger, Reinhard Schwödiauer, Ulf Panzer

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The applicability of dielectric analysis for in-situ-cure monitoring of aminoplast resins was tested by fundamental investigations. Cross-linking of aqueous urea formaldehyde and melamine formaldehyde resins was observed online by mounting a dielectric sensor into a joint of two glued veneers during a hot press process. The temperature dependent curing of these polycondensating binder systems and their post curing behavior were demonstrated. Considering the frequency dependence of the testing method and the approved influence of several factors (water content, ionic additives), dielectric analysis is providing an opportunity for in situ monitoring of the curing reaction and an evaluation of different binder systems.

Printability of particle boards – surface test methods

Language: German
Pages: 41 - 46
Authors: Ingrid Fuchs, Anissa Ghozzi, Rico Emmler

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Printing is an efficient way to enhance the productivity of the manufacture of furniture, floorings, or interior constructions. One of the main problems of printing on wood-based materials is to achieve a printable substrate surface. The mechanical and chemical surface properties of the substrates have a strong effect on the printing quality. Unfortunately, there is no approved methodology to characterise the surface of a wood based material in relation to its printability, yet. Therefore, different investigation methods such as roughness measurements in combination with surface swelling tests and contact angle measurements were studied to characterise the surface of industrially produced particle boards in order to assess their suitability for indirect gravure. Correlations were searched for between the obtained surface properties of the substrates and their printing quality. It can be assumed that it is not sufficient to determine a single parameter to evaluate the printability of a wood based material.

Review: Material use of lignin The options of the utilization; Part 1: Background, raw materials and use as a polymer

Language: German
Pages: 47 - 51
Authors: Thomas Hirth, Gerd Unkelbach, Moritz Leschinsky

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Lignin represents the most abundant natural source of aromatic molecules. If the production of chemicals from this source is desired, lignin from sulfur-free pulping processes especially from organosolv processes is preferably used. Preserving its polymer structure lignin can be used in a variety of chemical products. Most research was focused on its utilization in resins for the wood industry. The utilization of lignin for liquid wood, epoxy resins, polyurethanes and as a precursor for carbon fibres are options to obtain new interesting products.

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