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VOLUME 53, ISSUE 5/2012

Changes in properties of Acacia mangium from Vietnam by thermal modification

Language: German
Pages: 5 - 11
Authors: Trung Cong Nguyen, André Wagenführ, Le Xuan Phuong, Vu Huy Dai

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Acacia mangium is a fast-growing wood that is used in Vietnam more and more for different purposes. In the context of investigations Acacia mangium from Vietnam was thermally modified to improve its dimensional stability and durability. The thermal modification leads to many changes of properties such as the mass, the colour, the equilibrium moisture content, the density and porosity as well as bending and compression strength. This paper describes these changes and the relations between them and the modification conditions.

Reduction of density in the manufacture of particle boards by use of light-weight fillers; Part 1: Material and Methods

Language: German
Pages: 12 - 16
Authors: Tino Schulz, Winfried Hänel

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Currently available particle boards for furniture industry and interior outfitting with a density of more than 630 kg/m³ are too heavy for different applications. Therefore, the reduction of the density of particle boards by use of various light-weight fillers up to a range of 450 to 500 kg/m³ was investigated. Inorganic as well as organic filler materials were used in the middle layer to manufacture three-layered particle boards with densities in the area of 400 to 600 kg/m³ and thicknesses of 30 mm. The attained panel properties were compared to the requirements, as given in DIN EN 312 (2010), of particle boards of the P2-type – boards for interior fitments, including furniture, for use in dry conditions. Amongst others, positive results could be reached with extruded polystyrene, cork granules and expandable unexpanded polystyrene. The requirements concerning internal bond strength and thickness swell as for the P3-type could be met - with regard to bending properties partly not. Part 1 of this publication shows the current situation of lightweight panels as well as material and methods of experimentation. Part 2 will show selected results.

Tree barks as an alternative raw material for particle boards; Part 1: Influence of bark on the physical and technological properties

Language: German
Pages: 17 - 21
Authors: Carola Link, Redelf Kraft, Alireza Kharazipour

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Considerable quantities of bark accrue as a by-product of the timber harvest in Germany every year. These barks are currently mostly utilized for energy production or soil additives. However, the increasing scarcity of wood raw materials and required reduction of formaldehyde release in particle board manufacturing give rise to determine the usage of bark in particle boards systematically. This first part shows the influence of bark from spruce, pine, beech and oak on the physical and technological properties of three-layer particle boards. The results vary depending on the origin of the studied bark. However, the experiments revealed that using about 20 % of bark derived from spruce in particle board production has no negative effect on the mechanical properties of particle boards in comparison to boards manufactured without bark. In a following second part we will show the results of studying the formaldehyde emissions of particle boards containing bark.

Rheological and mechanical properties of extruded woodpolypropylene composites

Language: German
Pages: 22 - 26
Authors: Huong-Lan Nguyen, Robert Putz

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For the practical rheological characterization of extruded woodpolymer composites (WPC), a bypass rheometer tool was developed, which was adapted to a twin-screw extrusion system for fibre composites. The setup allows the investigation of process rheology of highly filled WPC formulations with 50 to 80 % wood content under

realistic processing conditions. It was found that the wood content has a great influence on the process rheology of the wood-polypropylene composites. The influence of additives on the melt rheology of WPC was also investigated. Furthermore, it was found that rheological parameters of the WPC melt have a direct influence on processing properties during extrusion as well as on the mechanical properties of the composites.

Nanocomposite ceramic materials for wood machining

Language: German
Pages: 27 - 31
Authors: Uwe Heisel, Dan Talpeanu, Rainer Gadow, Frank Kern, Frank Sommer

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In the present study different nanocomposite ceramic blades were produced. Independent of material systems used, first cutting trials were successfully carried out. Due to the relatively low hardness abrasive wear was visible in ZTA blades but lifetime could be increased clearly with ACY cutting blades. Up to now commercially available cemented carbide blades still outmatch lifetime of first ceramic test blades. A developed post-lapping process has shown accurate and reproducible micro-geometries at the crack tip, which stabilizes the cutting wedge and shows potential of future ceramic cutting tools.

Influence of sulphuric and nitrogen content of veneer species on calorific value

Language: German
Pages: 32 - 38
Authors: Christian Michel, Ulrich Schwarz, Dirk Kruse, Stefan Sarge, Sascha Jobke

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The calorific value of the tested wood varies in a range of 2 MJ/kg. The heating value is more strongly determined by the chemical and anatomical characteristics of the wood species than the conditions of the origin. A higher density can not, as claimed in some literature, automatically cause a higher calorific value. The chemical composition (ratio of lignin to cellulose), the content of combustible accessory constituents (fats, resin) and the proportion of non-combustible constituents (ash) are important factors affecting the heating value. In addition, the calorific value depends strongly on the moisture content. The conifers are consistently higher calorific value than hardwoods of the temperate zone. Ring-porous woods have a significantly low calorific value.

3D pore size characterisation by means of image analysis and mathematical morphology; Oriented strand board and particle board

Language: English
Pages: 39 - 45
Authors: Gernot Standfest, Manfred Dunky, Simon Kranzer, Bernhard Plank, Dietmar Salaberger, Alexander Petutschnigg

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In this paper the sub-micrometre computer tomography (sub-μm-CT) was used in order to investigate the structure of OSB and particle board. The data obtained were analysed using mathematical morphology and image analysis in order to obtain information on the pore size distribution. The observed distributions were found to follow Γ-law. Between the pore size distribution and the local density correlations were found in this investigation; due to the inhomogeneous structure these correlations

are weak for OSB; for particle board they are much better and similar as for MDF.

Using small diameter hardwoods in sawmill industry; Part 1: Yield calculation and technology assessment

Language: German
Pages: 46 - 50
Authors: Jörn Rathke, Hermann Huber, Alfred Teischinger, Ulrich Müller, Christian Hansmann

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The most effective production technology for the processing of small diameter hardwoods has been discussed for a long time in research and industry. Currently these resources are mainly used for firewood. An increase of the added value is expected by using small diameter hardwoods for material applications. Higher prizes of the logs are of high importance for a sound forestry management and the biodiversity of the forests. Therefore the development of new products, alternative production technologies and new sales possibilities of this specific assortment is of high economic interest. One major factor in this process chain are the production cost in the sawmill.

This cost varies, depending on the technology which is chosen. In part 1 of this publication, the yield of processing low diameter hardwood is calculated for the species sycamore, European beech, ash and European white oak. Following on that a comparison of various cutting technologies for the processing of small diameter hardwood is presented and discussed.

Review: Furniture quality – Brands and labels, test and assessment

Language: German
Pages: 51 - 55
Authors: Bernd Devantier

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Terms, such as brand, label, quality, test and certification, in combination with furniture provoke certain expectations. Brand quality is a term, which is related with a high expectation, and creation of value can be expected. The fulfilment of expectations is measured by customers who more and more consider concrete promises made by the marketing for furniture. Also in the furniture business, distance selling (via internet) will become increasingly important. The internet will continue to support the critical examination of brand statements. Independent third parties will support trust in quality statements of brands. Labels of test and certifications bodies shall document the reliability and independence of the assessments

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