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.
2010
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.
Authors
Andreas TreuAbstract
Wood modification with furfuryl alcohol is an extensively investigated process and already produced commercially. Furfurylated wood is in the focus of a European project on its use for the production of high performance windows. Different wood species were treated with furfuryl alcohol and tested on water uptake, dimensional changes, leaching in water, resistance to fungal degradation, and ecotoxicity. The results show a reduced water uptake and a reduced swelling of the furfurylated wood samples. A high resistance against fungal attack of the treated wood samples can be shown. A low amount of furfuryl alcohol was leached out and the water samples of two different leaching tests showed in general low toxicity. Southern yellow pine showed good results in all of the tests and has potential for the production of window frames according to the tests performed.
Authors
Andreas TreuAbstract
Furfurylation of wood samples can lead to different outcome (different chemistry) and product properties depending on parameters such as pH-value, catalyst, amount of water, time and temperature. Changes in the furfurylation process can even lead to a deterioration of product performance, such as lower durability in comparison to other furfurylated products. How is it possible to detect these changes in chemistry of a furfurylated wood product? To answer this question confocal laser scanning microscopy was used. The expectation was to detect different emissions of the auto fluorescent furfuryl alcohol if differences in chemistry exist. Additionally to the differences in emitted wavelength, the area in the wood structure of different emissions was under investigation. It was the aim to detect whether different product performance of a furfurylated product or different furfurylation processes could be related to changes in chemistry and this was expected to be visualized by CLSM.
Abstract
The furfurylation process is an extensively investigated wood modification process. Furfuryl alcohol molecules penetrate into the wood cell wall and polymerize in situ. This results in a permanent swelling of the wood cell walls. It is unclear whether or not chemical bonds exist between the furfuryl alcohol polymer and the wood. In the present study, five different wood species were used, both hardwoods and softwoods. They were treated with three different furfurylation procedures and leached according to three different leaching methods. The present study shows that, in general, the leachates from furfurylated wood have low toxicity. It also shows that the choice of leaching method is decisive for the outcome of the toxicity results. Earlier studies have shown that leachates from wood treated with furfuryl alcohol prepolymers have higher toxicity to Vibrio fischeri than leachates from wood treated with furfuryl alcohol monomers. This is probably attributable to differences in leaching of chemical compounds. The present study shows that this difference in the toxicity most likely cannot be attributed to maleic acid, furan, furfural, furfuryl alcohol, or 2-furoic acid. However, the difference might be caused by the two substances 5-hydroxymethylfurfural and 2,5-furandimethanol. The present study found no difference in the amount of leached furfuryl alcohol between leachates from furfurylated softwood and furfurylated hardwood species. Earlier studies have indicated differences in grafting of furfuryl alcohol to lignin. However, nothing was found in the present study that could support this. The leachates of furfurylated wood still need to be investigated further to identify the chemical differences between wood furfurylated with furfuryl alcohol monomers and furfuryl alcohol prepolymers.
Abstract
Measurements of heat production rate have been made on wood samples with the brown rot fungus Postia placenta at different moisture contents. The results clearly indicate that the heat production rate (a measure of respiration rate and activity) is moisture dependent. When the moisture content is decreased, less heat is produced, and when the moisture content is increased, more heat is produced. Isothermal calorimetry seems to be a measurement technique well suited to the study of rot fungal activity as a function of temperature and moisture content.