Thermo-hydro treatment (THT) of plywood produced from birch (Betula spp.) wood veneers was carried out in a multi-functional pilot device manufactured by WTT (Wood Treatment Technology). The treatment was conducted in elevated water vapour pressure conditions using four different treatment regimes: 150/10, 150/50, 160/10 and 160/50 (temperature, degrees C/duration, min). After the treatment, the THT plywood was subjected to the following tests: biological durability, anti-swelling efficiency (ASE), bending strength (BS), Brinell hardness (HB), equilibrium moisture content (EMC) and surface contact angle determination. THT improved most of the properties of the plywood. With increasing treatment severity, the dimensional stability and the resistance to white and brown rot fungi of THT plywood were improved. The EMC of THT plywood was lower than the untreated controls, and the surface became more hydrophobic. As a drawback, losses of BS and hardness were observed.

In this experiment an oil-in-water emulsion, suitable as a coating for wood surface protection, was obtained. The main components of this emulsion were linseed oil and an alkyd, mixed at a ratio of 1:2. The experiments were conducted to find a valid combination of solubilizing agents, capable of giving a stable emulsion. Several surfactants, obtained from different producers, were tested. The main factors considered were the nature of the surfactant and its hydrophilic-lipophilic balance (HLB). Our results confirmed that the most suitable surfactants were ethoxylated non-ionic types with a high HLB value, while surfactants based on the gemini technology showed a poor efficiency due to scarce solubility in water, which led to the separation of phases. Once the optimal emulsion composition was obtained, hydrothermally treated and untreated aspen wood samples were coated to evaluate the degree of coating absorption for two different substrates.

Thermally modified (TM) wood production has significantly increased in the last decade. The trend for TM wood residues should be similar - rapidly increasing, which has prompted this research on the possible efficient uses of these residues, such as sawdust. One of the possibilities could be the production of wood plastic composites (WPCs). In this work, three different hydrothermal modification regimes were used to modify birch boards. Modified and unmodified birch boards were milled to obtain sawdust. WPCs were made with a two-roll mill, and they consisted of 50 wt-% wood fibres + 50 wt-% polypropylene. Melt flow index (MFI), flexural properties, impact strength, microhardness water absorption and dimensional stability were tested. WPCs with TM wood showed improvement in flexural properties, MFI and other properties, however there was a decrease in impact strength. Scanning electron microscopy pictures of impact strength samples fracture surfaces were taken.

In the present study, changes in the chemical structure of the components of deciduous wood species, i.e., birch (Betula spp.), aspen (Populus tremula) and grey alder (Alnus incana) wood, after hydrothermal modification (HIM) were investigated by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and wet chemical analysis. The objective of this study was to elucidate the chemical changes in HTM deciduous wood dependent on the treatment parameters using chemical analysis and analytical pyrolysis and to evaluate the differences between the tree species. The results of both chemical and analytical pyrolysis studies demonstrate the effect of HIM on the chemical composition of deciduous wood. Wet chemical analyses showed that the hemicellulose content in wood decreased considerably (by 60-75%), whereas the cellulose and lignin contents increased by 6-20% and similar to 50%, respectively. The thermal destruction of hemicelluloses during HTM was also indicated by the water condensates, which contained acids and sugars. As a result of the HTM, wood transitions from a solid state to an aggregate state, in which the chemical composition of the gases (gas mixture) depends on the chemical composition of the wood. Py-GC/MS can quantitatively and promptly detect changes in the chemical composition of wood after HIM. As a result of the high HTM of wood above 160 degrees C, hemicelluloses are thermochemically destroyed and the primary products are acids (e.g., acetic acid and formic acid). Cellulose and lignin are more thermally stable than the hemicelluloses, as evidenced by the analytical pyrolysis results, which showed that the hemicellulose content in the wood decreased and the lignin content increased by revealing that the acid, ester and ether content in the gases decreased (by 24-33%) and the guaiacyl and syringyl derivative content increased (by 5-7%). Analytical pyrolysis is a promising method for understanding chemical transformations in HIM wood. (c) 2012 Elsevier B.V. All rights reserved.

Pine sapwood blocks were exposed to brown-rot fungi Postia placenta and Coniophora puteana for 1, 2, 3, and 4 months. Ion exchange chromatography method was used to determine the changes in sugar content during brown-rot decay. The most remarkable feature was the preferred degradation of mannose both by P. placenta (80.9% weight loss) and C. puteana (77.5% weight loss) in comparison to the control. It can be interpreted as a result of the preferred degradation of the backbone chains of O-acetyl-galacto-glucomannans.For scanning electron microscopy, the wood degradation sequences obtained by the fracture method were used. The fractured surface of cell wall reflected the pattern of degradation of cellulose microfibrils. The surface of secondary wall decayed by P. placenta revealed both smooth and uneven regions throughout the test. C. puteana retained uneven cell wall surface only after the first month, while later the surface became smooth. This suggests that P. placenta tended to degrade cellulose amorphous regions more readily, while C. puteana, possessing full enzyme complement, was able to degrade both amorphous and crystalline regions more readily.The water vapor sorption method was applied for microstructural characteristics of wood. The formation of new pores of size 2.1–9.9nm occurred during brown-rot decay, whose sizes and volume depend on the fungus culture and exposure time. It is assumed that the appearance of these pores is caused by the destruction of carbohydrates.

The dynamics of the biodegradation of wood by brown-rot fungi (Coniophora puteana, Poria placenta, and Gloephyllum trabeum) was investigated by the water vapour sorption method. The change in wood microstructure characteristics (specific surface and concentration of surface hydrophilic centres) with increasing exposure time correlated with reduction in mass and change in composition. Two-to-eight-nanometer-wide micropores, whose size and volume depended on the fungal species and exposure time, appeared in the wood. Methodological aspects of the application of sorption methods should be taken into account in the interpretation of the results.

Standard isotherms of the sorption of water, methanol, and benzene vapors on cellulose using a cellulose standard are determined. The standard, namely, mesoporous cellulose with specific surface of up to 350 m2/g, is obtained by the method of exchanging water in swollen cellulose with organic solvents. A comparison of the experimental sorption isotherm with the standard isotherm makes it possible to determine the specific surface of celluloses accessible a the given sorbate and, in combination with the Brunauer-Emmett-Teller adsorption equation, to characterize their surface properties. The identity of the sorption properties of the initial and dewatered (porous) celluloses relative to active vapors is shown, which evidences the assumed mechanism of swelling as the sorbent's division into morphological structures with the formation of new surface. A comparative analysis of the sorption properties of cellulose and silica, whose nature of active sorption centers is similar (weak acid hydroxyl groups), has been made. The affinity of the standard isotherms and close values of the cross-sectional area of different sorbates on both sorbents testify the similarity in their sorption behavior. Thus, the processes of sorption with rigid and swelling sorbents can be regarded in a unified context. Therefore, the adsorption models developed for rigid sorbents can be applied to cellulose sorbents to analyze their sorption properties.

To define the decomposition patterns of wood cell wall, three economically important brown-rot fungi, Coniophora puteana, Postia placenta, and Gloeophyllum trabeum were studied. Degraded Scots pine (Pinus sylvestris L.) sapwood blocks were analysed using 13C NMR spectroscopy, chemical, and water vapor sorption methods. C. puteana caused the most wood decay (55%) after 50 days of exposure, while the destructive abilities of P. placenta and G. trabeum were 32 and 30%, respectively. Hemicellulose was removed preferably to cellulose, but the intensity of depletion depended on the fungus species rather than the mass loss. P. placenta and C. puteana removed 11.8 and 14.7% of the lignin, respectively, while G. trabeum removed 25.2%. The possible re-polymerization of lignin stopped any further lignin degradation during attack by C. puteana and P. placenta, while G. trabeum continued to degrade lignin until the end of the test. Removal of lignin metoxyl groups and formation of the reactive phenolic hydroxyl groups can be coupled to the reactions of Fenton reagents or other powerful oxidants in acidic conditions. Removal of hemicellulose and lignin (primarily methoxyl groups) will promote further access of fungal metabolites to cellulose fibers. A common regularity of the surface A accessible to water molecules and the losses of the wood weight was obtained. The mass hydrophilicity of sorbent am in brown-rotted wood tended to decrease as the share of lignin increased.

Summary In the present work, the state of the copper ions absorbed by cellulose from aqueous solutions with different pH values has been studied by electron spin resonance (ESR), X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray analysis (EDXA) methods. It has been shown that the curve of copper sorption has a S-like shape characteristic for weak acid sorbents. At all pH values in ESR-spectra, an anisotropic Cu(II)-signal is registered. At pH > 4, the anisotropy of ESR-spectra decreases. At pH = 10, complexes connected by exchange interactions and diamagnetic clusters are formed. After the leaching of specimens, the ESR-signal practically disappeared. The decrease of the copper content in cellulose did not correlate with the change of the integral intensity of the spectra. The changes in ESR-spectra of copper-containing cellulose after leaching were explained by the formation of the Cu(II) diamagnetic clusters.

The specific mass of cellulose depends on the medium properties in which it is located (in which specific mass determination is carried out). A correlation between the cellulose specific mass ρ and the solubility parameter component δh (corresponding to hydrogen bonds) of the liquid in which ρ is located has been established. The dependence of ρ on δh is minimum at δh ~ 16 (J/m3)0.5, close to the δ value of cellulose (15.6 (J/m3)0.5). The highest ρ values have been obtained for saturated hydrocarbons (1.69 - 1.70 g/cm3) and the lowest for saturated alcohols (1.57 - 1.59 g/cm3). For cotton and wood cellulose, a common dependence of the ρ of moist cellulose on the relative content of water φ within the φ range of 2% to 70% has been obtained for 27 φ values: ρ = 0.916 (± 0.015) - 0.198 (± 0.008) Inφ. The extrapolated values of components ρ are equal to 0.92 g/cm3 and 1.70 g/cm3 for water and cellulose, respectively.

The information about grey alder (Alnus incana) and black alder (A, glutinosa) is fragmentary and scarce. The aim of the present work was to elucidate the chemical composition, morphological structure and sorption properties of alder wood to understand and prevent problems of alder wood pulp bleaching as well as to ground and extend the possibilities of alder wood application also in other fields.Results, different from those for other species (pine, birch, oak, etc.), were obtained. Water vapour sorption method, elektronmicroscopical observations, chemical analysis and C-13 NMR in solid state were used.