Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2011
Abstract
Wood as a hygroscopic material gains or loses moisture with changes in climate of the surrounding air. The moisture content influences strength properties, hardness, durability and machinability. Therefore the hygroscopicity is a very important property, last but not least for economic factors. Below fibre saturation, a change in moisture content causes shrinkage or swelling and anisotropic behaviour can be seen in the different growth directions. For a better understanding of the sorption behaviour of Scots pine (Pinus sylvestris L.) the variation between different adsorption and desorption curves has been investigated. Trees from 25 different sites in Northern Europe were collected and 3651 samples (1510 heartwood- and 2141 sapwood-samples) measuring 5 (T) x 10 (R) x 30 (L) mm were obtained. The sorption isotherms for all specimens were measured at 25 °C at relative humidities of 15, 35, 55, 75 and 95 % for both desorption and adsorption. The aim of this study is to investigate the influence of raw material variability on the sorption behaviour of Scots pine. Due to the different growing conditions, densities and wooden material (heart or sapwood) variations within the sample groups have been found. Correlations between moisture and density respectively latitude were investigated.
2010
Abstract
No abstract has been registered
Abstract
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Abstract
Wood protection is mainly based on chemical protection of wood. The disposal of wood preservative treated material causes restrictions in its later use or recirculation into the eco-cycle. A new protective system, electro-osmotic pulsing technology on wood, called PLEOT, is tested in a fungi test and in soil contact. Mass loss and moisture content of Scots pine sapwood samples was calculated after testing and an element analysis was performed on the sample powder. The results show that PLEOT- protected samples have nearly no mass loss after 4, 8 and 12 weeks of exposure to Coniophora puteana in laboratory trials. The samples protected with PLEOT showed lower moisture content but trace elements of metals in the samples after basidiomycete test compared to untreated samples. It is concluded, that neither the resulted wood moisture content nor the transferred metal ions in the PLEOT samples contribute to large amounts to the wood protection effect. Furthermore, the PLEOT system might give a protection for wood in soil contact. Further research on the mode of action as well as further tests including field tests are under planning.
Authors
Eirik NordhagenAbstract
No abstract has been registered
Abstract
Coated wooden claddings in building facades are widely used in the Scandinavian countries, and are often preferred to other materials. Wood experience an increasing competition from other materials that are less labor intensive at the construction site and materials with less demand for maintenance thru service life, and makes further development of wooden claddings essential. Growth of discoloring moulds on exposed coated wooden claddings is mainly of aesthetic concern, and is especially disfiguring for light-colored surfaces. Growth of surface fungi often initiates repeated cleaning and shorter maintenance intervals, which in turn increase the total cost of ownership for wooden claddings. Cost and effort of ownership is often an important factor considered when choosing a product, and the traditionally good market situation for wooden claddings is therefore threatened. The development of real-time PCR (polymerase chain reaction) and taxon-specific primers has provided new possibilities for specific detection and quantification of fungi in their natural substrates. In qPCR (quantitative real-time PCR), the accumulation of the PCR product is detected for each amplification cycle. An efficient and reproducible sampling and extraction of DNA is required for a high-throughput qPCR based quantification of discoloring fungi. The authors have now adjusted DNA isolation protocols and optimized real-time PCR assays for species specific detection of fungi frequently found on painted surfaces (Aureobasidium pullulans, Alternaria alternata, Cladosporium cladosporides, Ulocladium atrum).
Abstract
Scots pine (Pinus sylvestris) and especially its heartwood is one of the most common construction materials for general outer use e.g. windows or facades in northern Europe. It is considered being use class 3 and is according to EN 350-2 \"not treatable\". Reports from industry and researchers indicate that the heartwood treatability is not uniform. It is still unclear what causes these differences. To increase its durability by means of impregnation would be a contribution to extend the use of both a natural and native material. The understanding of a potential pattern analog to latitudinal/longitudinal origin or other forest or wood properties could help to improve the impregnation by better material selection. Scots pine samples from 25 different sites in 6 countries in northern Europe have been collected throughout autumn and winter 2009/2010. A circle of varying size containing approximately 30 trees was set up in a representative site of each stand. All diameters were measured and arranged in three classes. Three trees of each class were chosen randomly. Only the middle and upper diameter classes were used for studying heartwood permeability. The small diameter class had insufficient heartwood width to be processed. Samples of 20 x 20 x 50 mm were cut and conditioned in a climate chamber. The samples were impregnated with a water-soluble monomer furfuryl alcohol solution in a standard pressure/vacuum process. Results showed a generally low permeability but a few samples had an unexpected high ration of filling. Further on, the samples with the highest and lowest treatability will undergo anatomical and chemical tests to explain these properties.
Abstract
Scots pine (Pinus sylvestris) sapwood was investigated for variation in treatability using the wood modifying agent, furfuryl alcohol (FA) in water. The variation in treatability within trees, between trees and between different stands of Scots pine was studied. Investigated variables that reduced the residual variance significantly were: site location, latitude of site, height of trees, annual ring width, vertical and horizontal position in the tree and method of drying. Linear mixed model statistics were used and tree number was handled as a random variable. The best model reduced the treatability residual variance by 67%. Location was the single factor affecting treatability most. Differences in latitude between locations may be the reason for that. Latitude correlated negatively with the treatability. Within the trees, the treatability of sapwood increased with distance from ground and with distance from heartwood border. A small, but significantly better treatability was found for kiln dried wood (60A degrees C) compared to air dried wood (20A degrees C).
Abstract
Modification of wood with furfuryl alcohol or furfuryl alcohol prepolymer leads to a wood product with increased decay resistance, hardness and dimensional stability. In normal application, i.e. under Use Class 3 conditions, furfurylated wood can be regarded as non-toxic. This has earlier been demonstrated by toxic hazard tests on water leachates using relevant leaching procedures, e.g. the OECD Guideline 313 or the Dutch shower test procedure. These leachates showed slight to no toxicity towards standard aquatic test organisms. However, when using forced leaching procedures with limited amount of water such as the EN 84 procedure, slight to moderate toxicity to the same test organisms was observed, depending on furfurylation process. Furthermore, earlier studies have shown that leachates from wood treated with furfuryl alcohol pre-polymers have higher toxicity to Vibrio fischeri (luminescent marine bacterium) than leachates from wood treated with furfuryl alcohol monomers and that this probably is attributed to differences in leaching of chemical compounds. The ambition of the present study, was to investigate which chemical compounds in the leachates causes toxicity to the aquatic organisms V. fischeri and Daphnia magna (water flea). In this study five different wood species, both hardwoods and softwoods, treated with three different furfurylation processes, were leached according to two different leaching methods. The study shows that this difference in toxicity of leachates towards V. fischeri most likely cannot be attributed to maleic acid, furan, furfural, furfuryl alcohol or 2-furoic acid. However, the difference in toxicity might be caused by the substance 2,5-furandimethanol. Leachates from furfurylated wood still need to be investigated further in order to identify the chemical differences between wood furfurylated with furfuryl alcohol monomers and furfuryl alcohol prepolymer causing differences in toxicity to different organisms.