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OSB (oriented strandboards) made from Scots pine (Pinus sylvestris) were thermally post-treated at three different maximum treatment temperatures in the laboratory thermal treatment chamber of the Institute for Wood Technology Dresden (IHD). The OSB were supplied by a European manufacturer of OSB and bonded with methylene diphenyl diisocyanate (MDI). Post-treatment means that rather than thermally treating wood or strands before panel production, cut industry panels, i. e. 650mmx1200mm, were modified in IHD's lab kiln. The main goals of the thermal post-treatment of full-sized OSB were to improve the hygroscopic properties, i. e. to reduce the thickness swell (TS) and the equilibrium moisture content (EMC), as well as to improve the long-term properties creep behaviour and dimensional stability, without significantly reducing further mechanical properties like e. g. internal bond (IB) or bending properties, however. It was observed that the thermal post-treatment of the aforementioned OSB had a very positive effect on the moisture-related properties TS and EMC. The modified OSB showed far better values for said properties than the respective untreated ones. In can be concluded, that the thermal modification of OSB panels is possible and leads to very positive effects regarding their hygroscopic properties. [ABSTRACT FROM AUTHOR]

Abstract: The development of mould on wood surfaces depends on several factors. Although mould does not affect the mechanical properties of wood, it greatly reduces the aesthetic value of wood such as the sapwood of Scots pine (Pinus sylvestris L.), which is very prone to mould. In addition, adverse health effects of mould on humans are a great concern. Different types of dried and treated wood were used to observe whether they had enhanced durability against mould following an accelerated laboratory test method in a climate chamber. Samples were green, air-dried, industrially thermally modified, treated with copper-based preservative, and kiln-dried wood, which were tested within a single test run. The test produced the following main results: The thermal modification increased the durability of the wood, and the protective effectiveness of alternative treatments was comparable to that of commercially available copper-based treatment. However, the initial moisture content of the samples during mould exposure had a great influence on the onset of mould growth. The risk of mould susceptibility of industrial kiln-dried lumber can be reduced by drying using the double-layering technique and planing off the nutrient enriched evaporation surfaces. [Copyright &y& Elsevier]

Studying the impregnation and distribution of oil-based preservative in dried wood is complicated as wood is a nonhomogeneous, hygroscopic and porous material, and especially of anisotropic nature. However, this study is important since it has influence on the durability of wood. To enhance the durability of thermally modified wood, a new method for preservative impregnation is introduced, avoiding the need for external pressure or vacuum. This article presents a study on preservative distribution in thermally treated Scots pine ( Pinus sylvestris L.) and Norway spruce ( Picea abies (L.) Karst.) sapwood using computed tomography scanning, light microscopy, and scanning electron microscopy. Secondary treatment of thermally modified wood was performed on a laboratory scale by impregnation with two types of preservatives, viz. Elit Träskydd (Beckers) and pine tar (tar), to evaluate their distribution in the wood cells. Preservative solutions were impregnated in the wood using a simple and effective method. Samples were preheated to 170 °C in a drying oven and immediately submerged in preservative solutions for simultaneous impregnation and cooling. Tar penetration was found higher than Beckers, and their distribution decreased with increasing sample length. Owing to some anatomical properties, uptake of preservatives was low in spruce. Besides, dry-induced interstitial spaces, which are proven important flow paths for seasoned wood, were not observed in this species. [ABSTRACT FROM AUTHOR]

Scots pine ( Pinus sylvestris L.) sapwood was impregnated with aqueous solutions of phenol formaldehyde and methylated melamine formaldehyde resins and subsequently cured in an oven. One set of specimens was cured in plastic bags to avoid drying (wet curing) while another set of samples was heated and water was allowed to freely evaporate (dry curing). Macroscopic resin distribution was investigated using X-ray densitometry and infrared spectroscopy (FTIR-ATR). During dry curing, the resins migrated to the wood surface resulting in a gradient. Wet curing resulted in even distribution of the resins because it was immobilized due to condensation and precipitation in the wood. Neither densitometry nor FTIR-ATR was found to be generally applicable for investigating resin distribution in modified wood. Wet curing resulted in low cell wall bulking as compared to dry curing, probably because resin precipitated before drying. Storing impregnated wood prior to curing under non-drying conditions ('diffusion phase') also reduced cell wall penetration and bulking. [ABSTRACT FROM AUTHOR]

With thermal modification, changes in properties of wood, such as the presence of VOC and water-soluble carbohydrates, may occur. Thermal modifications under saturated steam conditions (160°C or 170°C) and superheated steam conditions (170, 185, and 212°C) were investigated by analysing the presence of water-soluble 5-(hydroxymethyl)furfural (HMF), furfural, and carbohydrates in heat-treated wood. The influence of thermal modifications on Scots pine, Norway spruce, and silver birch was also studied. Furfurals were analysed using HPLC at 280 nm, while monosaccharides and water-soluble carbohydrates were determined by GC-FID as their acetylated alditiols and, after methanolysis, as their trimethylsilylated methyl-glycosides, respectively. The amount of furfurals was larger in boards thermally modified under saturated steam conditions than those treated under superheated steam conditions. Generally, more of HMF than furfural was found in the thermally modified boards. In process water, in which saturated steam conditions had been used, furfural and only traces of HMF were found. Higher content of water-soluble carbohydrates was found in boards treated in saturated steam rather than in superheated steam. After modification in saturated steam, substantial parts of the water-soluble carbohydrates were due to monosaccharides, but only traces of monosaccharides were found in boards treated under superheated steam conditions. [ABSTRACT FROM AUTHOR]

In this study the thermal conductivity of different wood materials was determined. For this purpose, Scots pine (Pinus sylvestris L.), Uludag fir (Abies Bornmülleriana Matff), Oriental beech (Fagus orientalis L), Oak (Quercus robur L.), and Chestnut of Anatolia (Castanea sativa Mill.) woods were used. In the test, the thermal conductivity of the woods was measured according to procedure of ASTM C 1113-99 standards. The lowest thermal conductivity was obtained in the perpendicular direction of Scots pine samples as 0.156 Kcal/mh°C. The highest thermal conductivity was obtained from perpendicular direction of samples in Oriental beech as 0.331 Kcal/mh°C. [ABSTRACT FROM AUTHOR]

Abstract: In order to promote the use of Pinus pinea L. wood within the Migliarino-San Rossore Nature Reserve (Pisa, central Italy), three low-environmental-impact wood treatments, supposed to enhance natural durability, were compared. Impregnations with an oil-based preservative and natural waxes and a wood thermal treatment were tested in the field in accordance with standards ENV 12037 and EN 252. The above-ground test revealed that: P. pinea sapwood is more durable than Pinus sylvestris sapwood; all the alternative treatments showed a low mean decay level; wax and oil treatments performed as well as the traditional copper-based preservative; the natural durability class of P. pinea will only be calculated upon the complete failure of all reference lap-joints. The main outcomes from the in-ground test were: All the tested treatments increased the durability of wood, and the protective effectiveness of alternative treatments was comparable to traditional copper-based ones, or even superior in the case of heated oil. Taking certain mechanical and aesthetic limitations into account, all the treatments were suitable for the promotion of the P. pinea wood commodity in use classes 3 and 4. [Copyright &y& Elsevier]

The main objective of this work was to study the chemical composition of surfaces and ageing effects on acetylated pine ( Pinus sylvestris), heat treated spruce ( Picea abies), and furfurylated radiata pine ( Pinus radiata) in comparison to unmodified wood. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were the instruments of choice. Observation with a low-vacuum scanning electron microscope (LV-SEM) complemented the study. The spectroscopic information was also linked to a parallel wettability study on matched wood samples by the Wilhelmy method. The results show that XPS and ToF-SIMS are two powerful tools that in combination give complementary information, both quantitative and qualitative, and are well suited for observation of the ageing process of different wood surfaces. The hydrophobization process as a result of migration of extractives during ageing was well quantified by the XPS measurements and the results correlated well with wetting results. Several specific hydrophobic substances could be identified by ToF-SIMS measurements. [ABSTRACT FROM AUTHOR]

In this paper, the thermal conductivity and dielectric parameters for pine [Pinus sylvesttfs (L.)] woods were d~ermined in transverse directions for moisture conditions from oven-dry to 22 percent at a room temperature of 22 to 24 °C. Results indicate that the behaviors of thermal conductivity and dielectric parameters with moisture content and structural directions were similar. In general, the properties increased within the range studied with increasing moisture content. The radial values were similar to tangential values for both thermal conductivity and dielectric properties. The data presented here should be useful in most design problems where pine wood is subjected to microwave electric fields and heat changes. [ABSTRACT FROM AUTHOR]

AbstractColour evolution and colour changes were analysed from surface images of small specimens of three thermally-modified timber species using the CIEL*a*b*colour space. Upon heat exposure, the wood substance became orange and then approached grey irrespective of species; this was accompanied by a steady reduction in lightness. Colour changes were similar in the three woods at any given level of heat-induced weight loss (WL), whilst changes in the three coordinates of the CIEL*a*b*space in function of WL were different regardless of the wood species. For ΔL*, the profile was curvilinear and monotonous, while Δa* and Δb* bear a complex, non-linear profile. In turn, ΔE* was found to be highly influenced by the behaviour of ΔL*. It is proposed that ΔE* in thermally modified wood originates from chemical changes in the main wood polymers, more so in lignin than in polysaccharides, due to the darkening of the lignin itself. This was associated with the generation of chromophoric groups, mainly the increase in carbonyl groups appearing in the Fourier transform infrared spectra of lignin between 1710 and 1600 cm-1, particularly the emergence of quinone species. [ABSTRACT FROM AUTHOR]

Abstract  Scots pine sapwood (Pinus sylvestris L.) and Douglas fir heartwood (Pseudotsuga menziesii Franco) specimens were exposed in double layer field trials at 23 different European test sites under different exposure conditions (in total 27 test sets). The material climate in terms of wood moisture content (MC) and wood temperature was automatically monitored over a period of up to 7 years and compared with the progress of decay. The overall aim of this study was to establish dose–response relationships between climate factors and decay as a basis for the service life prediction of wood. The “Scheffer Climate Index” based on weather data collected at official meteorological stations at the different test sites poorly correlated with the corresponding decay progress and was therefore not a suitable tool for estimating site-specific decay potential. In contrast, the use of the combined material climatic parameters MC and wood temperature led to a feasible dose–response function and turned out to be a useful basis for service life prediction of wood. [ABSTRACT FROM AUTHOR]