VOLUME 53, ISSUE 4/2012

In this study, MDF was produced from three clones of poplar (Populus e. vernirubensis, Populus e. costanzo, P. e. 561.41) in order to consider the effects of steaming time and age on medium density. Age of poplar clones were 4 years and 12 years. Further to age of poplar clones, the influence of steaming time on MDF properties is investigated. The results show that increasing steaming time leads to decrease of internal bond and bending properties of the boards. Also, it is found that minimum swelling thickness of boards was obtained at 15 minutes steaming time because of fiber hydrophilic properties were decreased. There was no significant difference between strength properties of the boards made up of 4 years and 12 years old poplar clones except thickness swelling. The effect of clone its age on swelling thickness after 2 hours and 24 hours was significant and swelling thickness of the boards made by poplar clones 4 years old was less than that of made by poplar clones 12 years old.

The size distribution of wood fibres or particles as raw materials for fibreboards or particleboards is an important parameter for the production control which is currently measured using simple means such as sieve analysis. Today, automatic image processing methods for laboratory and on-line measurements are available which can be adapted to the material type. Shape measurements for separated particles together with weighted size distributions provide more detailed information than sieve analysis: E. g. the different lengths of particles from various wood species which originate from the same sieve fraction; the amount of shives and fibre bundles in MDF fibre material corresponding to the gap size in the refiner; different components (e. g. particles and fibres) in particle mixtures. The FibreShape system operated at Fraunhofer-Institut für Holzforschung Wilhelm-Klauditz-Institut (WKI) is a helpful tool for these investigations. In addition, using specific image processing procedures which were developed at WKI, it is also possible to recover and measure particle shapes in mat and board surfaces for a continuous monitoring of particle geometry in the production.

The thermal treatment of wood is a common process to improve properties. Usually bulk wood is being thermally modified. It seemed obvious to investigate how veneers with their much smaller thickness could be thermally modified. A further objective was to investigate whether plywood and moulded plywood parts could be made from thermally modified veneers. Advantages were expected with regard to the material its dimension stability and durability. Therefore, the application range can be extended, especially for outdoor uses (façade elements, seating furniture), but also for indoor application. There the advantage is in an improved appearance.

The Dascanova Technology is based on load bearing structure inside the fibreboard or particleboard. Its primary function is to increase the resistance to mechanical loads and can be achieved by using the density distribution within the board (while the advantages of full core material are taken). Saving the material in non-load bearing parts of the board and its weight reduction is an important effect of using this technology. The boards with internal load bearing structure could be produced by several different methods. In these laboratory experiments the fibreboards with 2D inner structure have been produced. The main principle, how the density inside the board has been distributed, is based on the lower compressibility of selected particles before pressing the final board. The modification of selected areas of the material results in creating areas with higher density. The analysis of final samples has been carried out by using computer tomography. The average density difference of 60 % between the internal load bearing structure and the rest parts of the board has been observed.

Nowadays the forestry and timber industry faces a lack of resources and therefore the development of alternative resources has become increasingly important. The present investigation focuses on the heretofore barely utilized potential of tree bark. Bark is a by-product of timber production in sawmills and exhibit very interesting technical properties. Within this research project insulation boards out of pine bark have been produced. Their properties seem to be promising with regard to thermal conductivity, heat storage capacity and mechanical characteristics. For this reason bark based panels could probably be used for civil engineering purposes.

This article describes an amino-based resin system (MUF) for application in ultra low emitting wood-based products. It is completes the AsWood® family. Results of a literature review are cited in which all published research results on emissions from untreated wood have been summarized and valuated. Deriving from this the AsWood® emission level can be specified. Emissions results from laboratory manufactured as well from industrial particle boards show that lowest emission values can be reached with the developed resin system. Different testing methods were applied to determine emissions from AsWood® products in comparison to untreated wood as well as conventional wood-based composites.

In future, newly built prefabricated residential houses should always be arranged according to the principles of Universal Design. Due to the demographic developments the most different user equirements from starting a family, changing family circumstances during life till nursing eth elderly at home must be observed. The Institut für Holztechnologie Dresden (Institute for Wood Technology Dresden) has worked out valuation standards in a research project which make it possible to review the user-friendliness related to Universal Design. Therefore different ways of use were defined. These aim at the use as intended. But also the foreseeable use is also noticed under inclusion of the competence restrictions of the elderly. Furthermore a building and equipment concept was worked out. Supported by this concept it has been proved that he implementation of the principles of Universal Design is feasible in building customary prefabricated houses economically.

Välinge Powder Technology is based on a dry powder mix of wood fibres and binders. The different ingredients will be modified to fit the intended application of the product. This powder mix is then scattered onto a carrier, usually an HDF-board and pressed under conditions similar to today’s DPL processes. The product achieved by this process can be either really plain with a flat, thin uni-coloured surface or very advanced with deep inregistered embossing and advanced printing patterns. The technology is extremely flexible and suitable for flooring, domestic and commercial, wall panels, kitchen tops and furniture components.

Thermally modified timber (TMT) is prepared industrially by high temperature treatment. The modification elicit, among others, drastic irreversible chemical changes in wood, due to which lignin becomes partially soluble. Using the nitroso-lignin method, originally designed to determine lignin sulfonates in waste water, it is possible to detect lignin in water extracts of thermally modified wood. Moreover the results reveal differences between wood of beech and spruce towards thermal treatment and offer undisputable evidence of the high sensitivity of beech wood lignin towards thermal treatment.