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VOLUME 59, ISSUE 4/2018

Resistance of modified wood against marine borers

Language: English
Pages: 5 - 11
Authors: Antje Gellerich, Christian Brischke, Holger Militz, André Klüppel

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Wood and wood products used for marine applications are exposed to an extremely harsh environment. Most Europe-grown wood species such as Scots pine or European beech are not durable against attack by marine organisms. To protect susceptible wood species, wood modification might be an alternative. This study focused on impregnation modification with thermosetting resins, acetylated and silica containing wood and was started in 2008. Results after nine years of exposure are presented. The results have shown that acetylation and modification with

thermosetting resins at higher weight percent gain (WPG) increased the durability against shipworms significantly. Therefore, the modified wood has the potential to be used in sea water contact. However, for a deeper understanding of the protection mechanisms further studies are needed to investigate the influence of process and curing parameters as well as the distribution of chemicals. To assess the suitability of these treatments for building materials in marine environment, such as groins, jetties as well as sea bridges, an upscaling to full size dimensions will be necessary in the future and has been initiated.

Process modelling by Machine Tool Data Analytics Machine integration enables online cutting path, wear factor and quality factor calculation

Language: German
Pages: 12 - 18
Authors: Jürgen Lenz, Engelbert Westkämper

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The goal of this research project was to show the feasibility and the potential of machine tool data analytics in the woodworking industry. This was done by an implementation of a demonstrator. New interfaces enable the possibility to conduct online machine tool data analytics. One analytics objective is the calculation of the cutting path. An approach to perform this calculation was shown. This approach proved to be precise and robust. By using the results of the cutting path calculation process modelling was conducted. Process models for tool wear and edge quality were acquired using regression analysis. The regression analysis resulted in characteristic field for the range of the tool life and the feed rate. These characteristic fields can be used to perform prediction. They can be acquired during regular operation without the loss of machining time.

Catalytically induced in situ polymerization of ethylene in the hierarchical porous wood structure

Language: German
Pages: 19 - 23
Authors: Julius Gurr, Gerrit A. Luinstra, Andreas Krause

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Introducing catalytically induced polyolefi n polymerization methods into the fi eld of wood science may open up a vast number of novel wood modifi cation possibilities, i. e. tuning the hydrophobic properties and with that creating the option of new functionalization to enhance the property profi le further. The scope of our ongoing research is focused on polymerizing ethylene within the wood structure by in situ polymerization techniques. This is achieved by a highly specialized catalytic system, consisting of a metallocene catalyst and an aluminum alkyl co-catalyst. This system exhibits promising features in the fi elds of polyolefi n nanocomposite production, and it has attracted interest in the macromolecular science community as well as in the industry. The approach followed in this study comprises three steps. In the fi rst step, small solid wood samples of pine sapwood are pre-treated with the co-catalyst trimethyl aluminum (TMA), which is adsorbed by the wood surface and adsorbed within the pores. In the second step, the metallocene catalyst is introduced, which is binding onto the immobilized co-catalyst. Hence, catalytically active sites are foremost formed on the wood surface and within the pores. In the third step, ethylene is introduc-ed under low pressure. Upon initiation of the ethylene polymerization, polyethylene (PE) is formed on the wood surface and inner pores. Field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDX) were utilized to analyse cross sections of the treated wood samples. The FESEM images did show fi lled, partially fi lled as well as empty cell lumen. The EDX analysis of the same cross sections displayed high shares of oxygen distributed along the cell walls, whereas negligible shares were distributed in the empty and fi lled cell lumen. The aluminum distribution, which is attributed to the co-catalyst, cumulates within the voids. This fi nding makes us assume that the cell lumen contain or even are fi lled with PE.

Particleboard based on wood waste material and bonded by hybrid resin of TF and PMDI; Part 1: The mechanical and physical properties of the particleboards

Language: English
Pages: 24 - 32
Authors: Mahmood Hameed, Eric Rönnols, Torleif Bramrydof

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Nowadays, alternatives to fresh wood and urea-formaldehyde as a synthetic adhesive system and other fossil origin adhesive systems are required. Wood waste materials are normally used for biofuel production or waste incineration. From environmental perspective, it is favourable to recycle wood material and use the concept of multiple sequential use than just burning it for short-term energy production. The objective of this study was to investigate the feasibility of manufacturing different variants of a combination of tannin-formaldehyde (TF) resin, PMDI-bonded (different ratios) particleboard from wood waste to clarify to what extent the replacement of PMDI as a costly fossil adhesive by tannin resin as cheap natural adhesive, is possible and still comply with the European standard EN 312 (2010), and compare them with particleboard from wood waste bonded by urea-formaldehyde (UF) resin. In this study, untreated wood waste material (type AI) was used to produce three-layered particleboards bonded by combination of tannin-formaldehyde resin and PMDI resin (TF-PMDI hybrid resin) and UF-resin. The particleboards were produced with a target density of 640 kg/m³. For each panel variant the mechanical and physical properties were analysed. The results point out that it is possible to manufacture three-layered particleboard variants based on recycled untreated wood waste material (AI) bonded by a combination of TF and PMDI hybrid resin with two ratios (30 % : 70 % and 40 % : 60 %), which demonstrated that the replacement of PMDI by 40 % tannin resin is possible and the produced particleboard still comply with the European standard EN 312 (2010) as well as comparable with particleboard bonded by UF resin. Furthermore, the mechanical and physical properties of particleboards achieve the requirements of European standard EN 312 (2010) for particleboards type P2. Specifically, particleboards bonded by a combination of TF and PMDI hybrid resin with two ratios (30 % : 70 % and 40 % : 60 %) show not only comparable flexural properties to those bonded by UF resin but also a competitive behaviour in thickness swelling and water absorption after 24 h.

Suitability of cement paste for the production of laminated wood-based panels; Part 1: State of the art and theoretical deduction of a new type of wood-based panel

Language: German
Pages: 33 - 40
Authors: Martin Direske, Christoph Wenderdel

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In the wood-based panel industry inorganic binders are solely used for the production of wood particle based boards. Hitherto, laminar bonding between inorganic binders and wood is only known in timber-concrete composite systems. In contrast to typically used organic binders, inorganic binders provide some benefits: such as lower formaldehyde emission, higher resistance to fire, moisture and chemicals. On the other hand it is possible to overcome some well-known disadvantages of inorganic-bonded parti-cleboards: such as high binder content, high density, hard machinability, lower strength. Part 1 of the publication gives an overview of the use of cement as inorganic binder for the manufacture of wood-based panels. Furthermore, common adhesive systems for face gluing of wood (e. g. veneers for the manufacture of plywood) are presented. Based on the material properties of plywood and cement-bonded particle boards the advantages as well as disadvantages of the wood based panel classes organic-bonded laminated wood boards and inorganic-bonded particle boards are compared. From this the potentials of cement-bonded laminated boards are derived.

Towards developing flame retardant high-gloss clear lacquers

Language: German
Pages: 41 - 44
Authors: Lars Passauer, Kurt Plöger, Raul Prieto, Jorge Prieto, Rule Niederstadt

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In many cases, decorative wooden surfaces for high-end furniture and interior applications are coated with transparent two component PU high gloss lacquers characterized by excellent optical properties and high mechanical and chemical resistance. Despite moderate inflammability PU high gloss coatings combust quickly and completely, when ignited. Due to material incompatibilities and insufficient effectiveness of conventional flame retardants, transparent high gloss PU lacquers cannot be adequately stabilized against inflammation. In this short paper current activities concerning the development of more efficient and compatible flame retardants and transparent high gloss coatings with improved flame retardancy are presented.

Development of test methods for assessing the bonding quality of multi-layer parquet

Language: German
Pages: 45 - 54
Authors: Jens Gecks, Gerhard Grüll, Rico Emmler, Peter Schober
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For bonding of multi-layer parquet no European specification or test method exist. The aim of the investigations was the development of a test method to assess the bonding quality. After a comparison of methods numerous variants of materials were tested using different mechanical and delamination methods. The samples were subjected to temperature and moisture stresses prior to testing. Selected methods were validated in a round robin test. It was examined whether the methods can be used in factory production control at the manufacturer. As a result a work standard containing a description of a delamination test was prepared. Depending on the purpose of the test the samples are stored under dry conditions or in cold water followed by drying prior to the assessment.

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