1,721,340 research outputs found
Modification of wood with silicon compounds. inorganic silicon compounds and sol-gel systems: a review
No full textThis review describes the treatment of wood with various inorganic silicon compounds. Among these compounds silicofluorides represent one of the long-known classes of wood preservatives based on silicon. Data on an organic fluorosilicon compound ("silafluofen") are additionally presented. The mode of action of these fluorides is based on their biocidal action. "Water glass", an alkali silicate, was able to enhance the durability of wood but showed some important drawbacks. Because of its high hygroscopicity and its high pH values, increased moisture absorption and strength loss of wood was frequently observed. Wood treated with tetraalkoxysilanes showed an enhanced dimensional stability, especially when the hydrolysis and the condensation of the silanes was controlled to react within the cell wall. Durability and fire resistance were improved to a certain degree and could be significantly enhanced by addition of boron compounds
Colour measurements and gluability investigation on red heart beech wood (Fagus sylvatica L.)
No full textAt present the light-coloured and workable beech wood is in great demand, especially in the furniture industry sector. Against that the red heartwood will be considered above all as inferior for higher value utilisation purposes. Untreated red heartwood from beech loses the colour intensity and will bleach out or become of grey discoloration gradually. While beech wood can be used only in the interior, the end users take much care about the colour stability of the product surface. That is why the colour stabilisation of differently treated beech red heartwood against the UV-Iight effect is an important field of research. In the frame of the investigation on the UV-Iight durability of red heartwood, the colour alteration in untreated red heartwood after different UV-irradiation cycles was measured in the CIE L a b colour coordinate system. Further measurements were done on beech wood samples after different surface treatments. But important questions also refer to the gluability of red heartwood. That is why the gluability of red heartwood solid wood was further investigation objective. In the investigation on the gluing behaviour of red heartwood the results were compared with those done on white beech wood. In addition, the influence of steaming on the stability after gluing has been investigated as well
Colour measurements and gluability investigation on red heart beech wood (Fagus sylvatica L.)
No full textAt present the light-coloured and workable beech wood is in great demand, especially in the furniture industry sector. Against that the red heartwood will be considered above all as inferior for higher value utilisation purposes. Untreated red heartwood from beech loses the colour intensity and will bleach out or become of grey discoloration gradually. While beech wood can be used only in the interior, the end users take much care about the colour stability of the product surface. That is why the colour stabilisation of differently treated beech red heartwood against the UV-Iight effect is an important field of research. In the frame of the investigation on the UV-Iight durability of red heartwood, the colour alteration in untreated red heartwood after different UV-irradiation cycles was measured in the CIE L a b colour coordinate system. Further measurements were done on beech wood samples after different surface treatments. But important questions also refer to the gluability of red heartwood. That is why the gluability of red heartwood solid wood was further investigation objective. In the investigation on the gluing behaviour of red heartwood the results were compared with those done on white beech wood. In addition, the influence of steaming on the stability after gluing has been investigated as well
Study on the impregnation quality of rubberwood (Hevea brasiliensis Müll. Arg.) and English oak (Quercus robur L.) sawn veneers after treatment with 1,3-dimethylol-4,5- dihydroxyethyleneurea (DMDHEU)
No full textPhotodegradation of thermally-modified Scots pine and Norway spruce investigated on thin micro-veneers
No full textThe exposure to ultraviolet light results in surface photodegradation of uncoated wood during exterior application. When using thermally-modified wood in exterior applications, chemical changes that occur during the modification process might affect a subsequent photodegradation. This study investigates the impact of artificial weathering on the photodegradation of thin micro-veneers of thermally-modified Scots pine and Norway spruce by means of FT-IR spectroscopy and micro-tensile strength testing. FT-IR spectra revealed photodegradation reactions of lignin that resulted in the disappearance of the peak at 1508 cm(-1) after 144 h, irrespective of the thermal modification process. Loss in micro-tensile strength by photodegradation was higher for finite- than for zero-span micro tensile strength as a result of the loss of amorphous carbohydrates. Although strength loss of unweathered veneers was evident for thermally modified wood, the rate at which strength loss occurs during artificial weathering was considerably decreased by the thermal modification process. It was concluded that the amorphous carbohydrates were less degraded during artificial weathering as they were already pre-degraded during the thermal modification process.International ThermoWood Association (Helsinki, Finland
Microbial attack of acetylated wood in field soil trials
No full textMicroscopic evaluation of microbial attack in the acetylated wood after a long term exposure to the field soil was the main concern of the current research. Stakes of wood were cut from beech, poplar and Scots pine wood and acetylated by using acetic anhydride to achieve different weight percent gains (WPGs). Afterwards, the stakes were exposed to the field soil for 350 weeks according to EN 252. Small specimens were cut from the stakes, sectioned and stained for microscopic studies. Small blocks were also prepared for scanning electron microscopy (SEM). Microscopic observations indicated that the soft rot was dominant rot fungi in the field soil and decayed the non-acetylated wood severely and attack also the moderately acetylated wood slowly. Bacteria were also in close association with the soft rot fungi to degrade the acetylated and the non-acetylated wood. In the moderately acetylated wood, white rot decay was at developing stage, while it was at initial stage at the highest WPGs. Microscopy revealed that the initial stage of the decay was begun at the highest WPGs and it was at developing stage of the decay in the moderately acetylated wood. The less development of the decay in the acetylated wood comparing the non-acetylated wood proved very good protection of the wood against the soil microorganisms due to the acetylation after 7 years period. Soft rot and white rot decays were observed in the non-acetylated and the acetylated wood at the same time. No brown rot decay was observed in those woods. Bacteria were seen in all wood types. The bacteria cooperated generally with the soft rot fungi to degrade the non-acetylated wood or limit themselves to pits at the higher degrees of the acetylation. (C) 2009 Elsevier Ltd. All rights reserved
Laboratory Tests of The Performance of Dmdheu, Siloxane and Water Glass Modified Wood Against Blue Stain Fungi
No full textSpecimens of Scots pine sapwood (Pinus sylvestris) and Beech wood (Fagus sylvatica) were treated with an amino-alkyl-functional oligomeric siloxane, a sodium water glass solution and 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU). Untreated and biocide treated specimens were used as references. Four different test versions with the test fungus A. pullulans were carried out to investigate the suitability of predicting blue stain in service from modified wood in laboratory screening tests. The results showed that the infestation of blue stain was depending on the test version. The water glass treatment could prevent blue stain in every test version for specimens of Scots pine sapwood. The DMDHEU and siloxane treatment could reduce the surface discoloration, but not fully prevent fungal infestation. Based on the results of the different test versions it can be concluded that the most appropriate test method for uncoated modified wood was the use of vermiculite and the inoculation with spore suspension."Deutsche Bundesstiftung Umwelt" (DBU
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