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This paper deals with the results of a study of the thermodestruction of the earlywood and latewood in the 1988-1998 growth rings of Gmelin larch ( Larix gmelinii (Rupr.) Rupr.) trees growing along the polar tree line (7052′53″N, 102°58′26″E, Taimyr Peninsula). The study used methods of thermogravimetry (TG/DTG) and differential scanning calorimetry (DSC). Thermogravimetric data obtained were analyzed by Ozawa-Flynn-Wall kinetic model. We determined macrokinetic parameters of thermodestruction. Earlywood and latewood showed no significant difference in cellulose/hemicellulose/lignin ratio, whereas they differed significantly in destruction average value of activation energy (197.55 and 55.90 kJ mol, respectively). Our analysis of the correlation of thermodestruction values with mean monthly air temperature and precipitation revealed that component composition of both earlywood and latewood was influenced more by the weather conditions at the beginning of the growing season (April-June). Air temperature had markable influence on the wood component composition during cell wall synthesis only in latewood, whereas precipitation influenced the composition in both latewood and earlywood. TG/DTG and DSC methods were found to be promising for developing information on biochemical composition of early and latewood tracheids in stems and for identifying the extent of the influence of climatic changes on cell wall synthesis. [ABSTRACT FROM AUTHOR]

The aim of this paper was to determine the moisture desorption isotherms and essentials thermodynamic properties of two Oak wood varieties. Desorption isotherms were measured using a static gravimetric method at 50, 60, 70 and 80 °C within the range of 5-90 % relative humidity. The equilibrium moisture content decreased with increasing temperature and decreased with decreasing relative humidity at a constant temperature. The 'Thermodynamic' sorption equation was found to be the best for describing the experimental moisture sorption isotherms of woods within the range of temperature and water activity investigated. The Fiber saturation point, deduced from the 'Thermodynamic' model parameters, depends on the temperature and varying from 22.6 to 54.4 (% kg water/kg dry matter). Isosteric heat of desorption and differential entropy were calculated by applying Clausius-Clapeyron equation to the desorption data fitted by the 'Thermodynamic' model. The isosteric heat of desorption and the differential entropy decreased with increasing moisture content according to an exponential law equation and varying from 2.03 to 31.14 kJ/mol and from 73.98 to 4.34 J/(mol K), respectively. The linear relationship between differential enthalpy and entropy satisfied the enthalpy-entropy compensation theory. The sign of Gibbs free energy was found to be positive (+283 J/mol) and (+97 J/mol) for Quercus robur and Quercus canariensis, respectively. The isokinetic temperature was found to be greater than the harmonic temperature. Based on the enthalpy-entropy compensation theory, it could be concluded that the moisture desorption isotherm of Oak wood is a non-spontaneous and enthalpy-controlled process. [ABSTRACT FROM AUTHOR]

In this study, silica sol (SiO sol) and KCO were used as flame retardants for wood. The synergistic effect of SiO sol and KCO on the flame retardancy, leaching resistance, and thermal properties of wood was investigated. The limiting oxygen index results revealed a significant improvement in the flame retardancy and leaching resistance of the wood sample treated with KCO and SiO sol using the double bath technique. The thermal analysis results showed that the synergistic effect of KCO and the SiO sol effectively prolonged the degradation of the wood sample during the charring stage and improved the stability of the char residue. The thermogravimetry-mass spectrometry analysis and scanning electron microscopy results showed that KCO catalyzed the degradation reaction of the wood sample at lower temperatures resulting in an increase in the water and carbon dioxide output, and the SiO sol formed a compact and melted barrier on the surface of the char residue, which hindered the transfer of heat and combustible gases in the condensed phase. Thus, the combination of KCO and SiO sol proves to be a promising flame-retardant system for wood. [ABSTRACT FROM AUTHOR]

Ensuring reliability of data on thermal properties of wood-based panels is important for manufacturing processes, especially when it is recommended to shorten the cooling phase and stack the panels in hot conditions. Prediction of the heat transfer during cooling phase and normal or hot stacking based on accurate data is essentially important for attaining panels of required properties. The thermal properties are also required when designing houses, especially low-energy or passive ones. Therefore, a water calorimeter was adequately designed and constructed to ensure improvement in the accuracy of the specific heat measurements. The calorimeter was used to determine the specific heat. The attained accuracy estimated by the relative error was significantly increased, and the error values were less than 2 % for all types of the investigated particleboard and OSB. In case of low-density fiberboard (LDF), the maximum value of the relative error did not exceed 4 %. It was also shown that high accuracy required for the specific heat measurements was achieved for experiments in which high-mass samples were used, in contrast to measurements for such samples in traditional DSC systems. The results for the specific heat were within the range from 1420 to 1450 J/kg K for LDF and all types of particleboard. The effect of the investigated material density on the specific heat was not found. The only exception was in case of OSB for which the specific heat was ca. 1550 J/kg K, and it was approximately 100 J/kg K higher when compared to other panels. [ABSTRACT FROM AUTHOR]

An asymmetrical two-layer laminated densified wood product is prone to cupping when it is placed in a fluctuating moisture environment. This study was aimed at developing a 2D finite element (FE) model to simulate this situation. Two types of specimens with two thickness ratios of 0.18 (type I) and 0.58 (type II) were prepared. A 6-week moisture and temperature treatment was conducted. The cupping value of deformed specimens was measured for verification. The major results were: (1) The cupping value of type I specimens experimentally measured and predicted was 0.307 and 0.327 mm, respectively, while that of type II specimens was 0.440 and 0.396 mm, respectively; (2) FE and experimental results were in good agreement since the FE results lied in the 95 % confidence interval of the experimental results. The developed FE model can be used to predict the moisture-induced cupping of a two-layer laminated wood product. [ABSTRACT FROM AUTHOR]

Cupping is a critical issue that affects the performance of a two-layer laminated densified wood product in service. Many parameters including material properties and product geometry can influence the cupping. It is more efficient to study the influence of these parameters on cupping using a model than by testing. A model sensitivity analysis is helpful in identifying key parameters so that product design can be optimized. This paper expanded the discussion on the finite element model developed and its application. It was found that (1) swelling/shrinkage coefficient and modulus of elasticity in the tangential direction and equilibrium moisture content were three key material parameters; (2) increasing the modulus of elasticity could offset part of cupping; (3) thickness ratio of two wood layers, as a key geometry parameter, was independent of three key material parameters; and (4) the optimal thickness ratio of two wood layers was 0.12. [ABSTRACT FROM AUTHOR]

To clarify the decay resistance effects of wood treated with different preservatives, the thermal behavior of treated samples was investigated. A thermal dynamic model was established using a mathematical method. The results showed that untreated Pinus massoniana had maximum mass loss, and the decay resistance effects of this species treated with different preservatives improved with an increase in the largest mass loss of pyrolysis. The pyrolysis can be divided into primary pyrolysis and secondary pyrolysis reactions in the lower and higher temperature regions, respectively. The activation energy represents a different degree of reduction from the primary pyrolysis reaction to the secondary pyrolysis reaction. The higher the retained cellulose content, the higher the activation energy. The sample's activation energy in the primary pyrolysis reaction can represent the decay resistance effects of wood treated with different preservatives. [ABSTRACT FROM AUTHOR]

In the Great East Japan Earthquake on March 11, 2011, large amounts of disaster waste were generated by the earthquake and subsequent tsunami. Much of the mixed wood waste was stored in a temporary storage facility for an extended period of time, and fire broke out due to spontaneous ignition. Consequently, it is now the practice that when a metropolitan epicentral earthquake occurs, disaster waste will be generated and stored locally. Fire caused by the same type of spontaneous ignition is a grave cause for concern. Thus, in order to prevent such fires, we evaluated the thermal behavior of the oxidation heat of the wood that was believed to be the cause of the heat generation in disaster waste. As a result of studies using TG-DTA and TAM, it was revealed that the thermal danger of wood increases due to increases in the temperature and in the concentration of unsaturated fatty acids in the wood. It is thought that the oxidation heat of the unsaturated fatty acids contained in the waste wood contributed to heat generation near 70 °C after heat generation by fermentative bacteria. [ABSTRACT FROM AUTHOR]

Adhesives based on renewable resources have inferior efficiency compared to the synthetic ones. To improve the adhesive properties of soy protein isolate (SPI) adhesives, a new method of thermally modifying SPI was developed. The commercial SPI powder was thermally modified in a vacuum chamber at different temperatures (50, 100, 150, and 200 °C). Thermally modified and unmodified SPI powders were dispersed in distilled water and stirred at 24, 50 or 90 °C. Dispersions were prepared without and with pH adjustment to 10.0. The viscosity of the resulting adhesives was measured. Effective penetration and bond strength in longitudinal tensile shear were tested with bonded beech specimens. Regardless of the pH value and dispersion preparation temperature, SPI thermally modified at 150 and 200 °C exhibited no adhesive properties, while adhesive bonding was achieved with SPI modified at 50 and 100 °C. Adhesives without pH adjustment had viscosity below 28 mPas and exhibited no adhesive penetration. pH adjustment increased the viscosity and adhesive penetration, which improved the adhesive bond strength. Thermal modification at 50 °C resulted in improved wet shear strength, while the temperature of 100 °C deteriorated it. Increased dispersion preparation temperature to 50 °C increased wet shear strength, while temperature of 90 °C decreased it. The combination of thermal modification at 50 °C, dispersion preparation at 50 °C, and pH increase resulted in an adhesive with the highest shear strength. [ABSTRACT FROM AUTHOR]

Effects of heat-treatment on longitudinal permeability of circular and square wood specimens were studied here. Specimens were heated to 50, 75, 100, 125, 150, and 185 °C. Results showed that permeability increased at the lowest temperature due to shrinkage; then, it decreased due to irreversible hydrogen bonding and stiffness. The highest temperature increased permeability due to micro-cracks. The higher perimeter in the square specimens aggravated the effects of heat treatment. [ABSTRACT FROM AUTHOR]

Effects of zinc-oxide nanoparticles on physical and mechanical properties, as well as biological resistance of untreated and heat-treated beech wood were investigated in this study. Test specimens were prepared from sapwood and impregnated with a 5,000-ppm nano-zinc-oxide (NZ) suspension with a size ranging from 10 to 80 nm at 2.5 bars of pressure and using the Rueping process for 20 min. Control (C) and nano-zinc-oxide-impregnated specimens after (NZA) and before (NZB) heat treatment were divided into four subgroups of unheated (C and CNZ), heated at 50, 145 and 185 °C. Heat treatment resulted in a significant decrease in mechanical strength at temperatures of 145 and 185 °C. Heat-treated specimens showed less dimensional instability and fungal degradation. Impregnation with nano-zinc resulted in a slight and significant increase in weight loss and biological resistance against Trametes versicolor. The results showed that the impregnation significantly decreased the water absorption of the specimens. Impregnation before heat treatment showed considerable effect on the properties of wood compared to that of untreated ones. [ABSTRACT FROM AUTHOR]

This research work aimed at studying the effects of oleothermal modification of fir wood by using combined soybean oil with maleic anhydride (OHT-MA) to achieve lower treatment temperatures and enhance physico-mechanical properties. Wood blocks were oleothermally treated with soybean oil and OHT-MA at five different treatment temperatures (100, 120, 140, 160 and 180 °C) for three different holding times (30, 60 and 180 min). Afterward, physical and mechanical properties of the treated samples were determined, i.e., density, water absorption and volumetric swelling as the physical properties and bending strength, compression parallel to grain and impact load resistance as the mechanical properties. Results revealed increases in densities and reduction in water absorption as well as volumetric swelling of all treated samples. The mechanical properties were affected by OHT-MA treatment at different temperatures. Bending modulus of elasticity as well as compression parallel to grain was increased due to OHT-MA treatment. In addition, there was less reduction in impact load resistance of the treated samples. It was revealed that the OHT-MA enhanced wood properties at low treatment temperatures as well as shorter holding times. [ABSTRACT FROM AUTHOR]

Melamine formaldehyde-furfuryl alcohol copolymer was impregnated into softwood in combination with 1,3-dimethylol-4,5-dihydroxy ethyleneurea, a crosslinking agent, nanoclay, and a renewable polymer, collected as gum from a local plant ( Moringa oleifera) under vacuum condition and polymerized by catalyst heat treatment. Fourier-transform infrared spectroscopy, X-ray diffractometry, and scanning electron microscopy were used to characterize the nanocomposites. Transmission electron microscopy showed uniform distribution of nanoclay in the composites. The mechanical properties were improved after the addition of plant polymer. The plant polymer had a marked influence on the flammability and thermal stability of the prepared composites. The apparent activation energy was determined by Ozawa-Flynn-Wall's and Vyazovkin methods. The activation energy of the composites decreased up to a certain decomposed fraction thereafter it remained constant. Higher the plant polymer content higher was the activation energy of the prepared composites which indicated a better interfacial adhesion and thermal stability. [ABSTRACT FROM AUTHOR]

The effect of the thermo-hydro-mechanical (THM) densification in a closed system on the set recovery and thermal stability of lime ( Tilia cordata) wood was evaluated. The THM densification process consists of four steps: plastification, densification, post-treatment and cooling. The THM-densified wood samples were subjected to three different post-treatment temperatures, and for each one, three different periods were used. Comparison between THM-densified wood sample without and with post-treatment at different temperatures and times was made. The set recovery tests showed that the post-treatment at higher temperatures and times improves the dimensional stability of the samples suggesting a permanent fixation of the transversal compression, but also reduces their thermal stability, by having lower temperatures corresponding to the maximum decomposition rate, lower values for the mass loss at the end of decomposition stage and lower values for the kinetic parameters. The samples with post-treatments at lower temperatures showed high set recovery values and exhibited higher values for the temperatures corresponding to the maximum decomposition rate, lower values for the mass loss at the end of the stage and higher activation energies and reaction orders. [ABSTRACT FROM AUTHOR]

Birch wood ( Betula pendula) samples were treated in a thermal regime (140, 160, 180 °C) for 1 h and investigated by means of scanning electron microscopy (SEM). SEM microimages of the wood cross-section were taken from one and the same place before and after the thermal treatment (magnification 100-2,000×). The results of measurements of areas and linear sizes of the birch wood cells show significant changes, which depend on the thermal treatment conditions and the type of the cell: libriform, tracheid, vessel and ray. After the treatment at 180 °C, the integrity of wood morphological structure begins to break up. Voids and cracks are formed between fibres, thus leading to a decline in the mechanical properties of the wood. [ABSTRACT FROM AUTHOR]

The effects of laser incising on the surface of heat-affected zones (HAZs) and liquid uptake of wood were examined. Deep pin holes were incised on the tangential section of the wood with a laser beam of 1 kW in power with varied pulse widths, and the HAZs of the holes were investigated using scanning electron microscopy. The length of liquid uptake passing through HAZs surfaces was then measured. It was observed that the HAZs were unable to maintain normal porous structure, and smooth surfaces such as that of wood charcoal were also not observed. This is because the composite of the middle lamella completely melted, which led to a decrease in the length of liquid uptake. In addition, the release of high gas-pressure and thermal energy during the laser-incising process did not damage the tylose and the aspirated pit in the longitudinal direction. Because of this, the liquid movement remained blocked. However, the incising holes provided additional liquid-intake points, resulting in greater intake capacity. Moreover, it was observed that improvement of liquid impregnation is related to hole diameter. [ABSTRACT FROM AUTHOR]

The present study investigates the effect of heat treatment of untreated and nano-silver-impregnated Populus nigra, Populus deltoides and Fagus orientalis on the physical and mechanical properties. Specimens were impregnated with a 200-ppm aqueous silver nanoparticles suspension. Heat treatment was carried out at temperatures of 135 ± 3 °C and 185 ± 3 °C. Nano-silver impregnation aggravated the effects of heat treatment. Although significant in some cases, nano-silver impregnation did not seem to have great effect on physical properties. It may be concluded that although NS impregnation aggravated the effects of heat treatment on solid woods, other factors may also be involved such as the species and density of the wood. [ABSTRACT FROM AUTHOR]

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]

Wood-polymer nanocomposite (WPNC) based on styrene-acrylonitrile copolymer (SAN), γ-trimethoxy silyl propyl methacrylate-modified TiO nanoparticles, and nanoclay was prepared by impregnation. The flexural, tensile, and flame-retardant properties were improved. UV stability was evaluated by photo-induced weight loss, FTIR, loss in mechanical properties, and scanning electron microscopy. The results showed that UV stability was maximum for wood sample treated with SAN/TiO (0.5 %)/nanoclay (0.5 %). The presence of TiO nanoparticles in WPNC-exhibited antibacterial activity. [ABSTRACT FROM AUTHOR]

Fracture toughness of wood and wood composites has traditionally been characterized by a stress intensity factor, an initiation strain energy release rate ( G) or a total energy to fracture ( G). These parameters provide incomplete fracture characterization for these materials because the toughness changes as the crack propagates. Thus, for materials such as wood, oriented strand board (OSB), plywood and laminated veneer lumber (LVL), it is essential to characterize the fracture properties during crack propagation by measuring a full crack resistant or R curve. This study used energy methods during crack propagation to measure full R curves and then compared the fracture properties of wood and various wood-based composites such as, OSB, LVL and plywood. The effect of exposure to elevated temperature on fracture properties of these materials was also studied. The steady-state energy release rate ( G) of wood was lower than that of wood composites such as LVL, plywood and OSB. The resin in wood composites provides them with a higher fracture toughness compared to solid lumber. Depending upon the internal structure of the material, the mode of failure also varied. With exposure to elevated temperatures, G for all materials decreased while the failure mode remained the same. The scatter associated with conventional bond strength tests, such as internal bond and bond classification tests, renders any statistical comparison using those tests difficult. In contrast, fracture tests with R curve analysis may provide an improved tool for characterization of bond quality in wood composites. [ABSTRACT FROM AUTHOR]

Effect of artificial weathering on the wettability of three heat-treated North American wood species (jack pine, aspen, and birch) is studied from the point of view of the structural and chemical changes taking place on the wood surface. Weathering increases wettability of all three heat-treated woods by water. Changes in wettability during artificial weathering differ according to heat treatment procedure and wood species and are likely due to combination of structural and chemical changes of the surfaces. Scanning electron microscopic analysis indicates that cracks form due to degradation taking place during weathering. As a result, water has easier entry into the cell wall, which consequently increases wettability. IR spectra suggest that the OH/CH ratio for heat-treated specimens is inversely proportional to the contact angle regardless of the type of wood species. The presence of cellulose-rich layer on wood surface and increasing amount of amorphous cellulose transformed from crystallized cellulose due to weathering result in increase in hydroxyl; consequently, it increases heat-treated wood wettability. [ABSTRACT FROM AUTHOR]

Quality assessment of thermally modified wood has evolved as one of the major fields in the research on thermal modification of wood. This study investigates NIR spectroscopy in combination with the pattern recognition method of soft independent modeling of class analogies (SIMCA). Focus is put on identifying different treatment intensities of thermally modified samples of beech, ash, and Norway spruce. The results indicate that SIMCA classification based on NIR spectroscopy could be used for quality control of thermally modified wood. The method might be applicable for producers (pre-delivery checks) and customers (reception control). However, transfer from laboratory to industrial conditions needs further investigation. [ABSTRACT FROM AUTHOR]

The second part of a comprehensive review of the literature on wood published in the Journal of Materials Science since its inception in 1966 is presented. The topics reviewed include wood modification and surface treatment, the thermal stability of wood and resistance to fire, the physical properties of wood chars and wood-based carbon materials, and the structure-related properties of wood-cement and wood-polymer composites. The articles reflect the wide range of techniques utilised to improve wood properties, the role of wood as a precursor for carbon-based materials and cellular ceramics and the application of wood as a composite reinforcement. JMS is in the vanguard of the latest developments in all these disciplines. [ABSTRACT FROM AUTHOR]

The ignition of various wood species by exposure to the radiation of a DKsR-10000 xenon lamp was investigated. Time dependences of ignition delay on the radiant energy intensity were obtained for various wood species: cedar, larch, pine, birch, and aspen. The effect of the initial temperature and moisture content of wood on the ignition time was studied. The ignition temperature of pine and birch wood for various radiant energy intensities was determined by an optical method. It is shown that the ignition time of pine wood decreased by a factor of 1.5-2 as the initial temperature of samples was increased by 100 degrees. It was found that the ignition temperature of wood increased with increasing radiant flux density and depended on the wood species. Increasing the wood moisture content by a factor of 10 increased its ignition time by more than 50%. [ABSTRACT FROM AUTHOR]

In this study the thermoplastic flow behavior of steamed wood flour was investigated. First it was demonstrated that steamed Japanese beech flour flowed out of the nozzle under compression at high temperature in a thermal flow test with a capillary rheometer. The effects of the steaming temperature, steaming time, compressive pressure, and moisture content of wood flour on the thermal flow temperature were examined. It was shown that the higher the steaming temperature and compressive pressure, the lower the thermal flow temperature. Also, the thermal flow temperature of the sample steamed at 200°C for 20 min became lowest and increasingly higher over time. Furthermore, the thermal flow temperature became linearly low with increasing moisture content of the sample under 15%, whereas it became essentially constant over 15%. It is clarified that compressive pressure and moisture content as well as the steaming conditions profoundly affect the thermoplastic flow behavior of steamed wood flour. [ABSTRACT FROM AUTHOR]

The ultimate strength of bolted and dowelled connections in timber members at ambient temperatures have been assessed using Johansen’s yield equations in Europe and USA. More recently, several researchers have begun to investigate the strength of bolted and dowelled connections at elevated temperatures. Research has been carried out at the University of Canterbury to investigate the application of Johansen’s yield equations to the prediction of the failure strength of bolted connections in fire conditions. A series of single bolted connections using steel side plates was heated at constant temperature for several hours, then loaded to failure and used to determine the embedment strength of the wood over a range of temperatures from ambient to 300°C. The temperature-dependent embedment strengths are employed in Johansen’s equations for connections using a central steel plate as well as connections using steel and wood side members. Comparisons are also being made with the results of several similar connections tested in fire conditions and show considerable promise for predicting failure of such joints. A proposal for implementation of an easy-to-use approach for the prediction of the fire resistance of bolted joints is discussed in the paper, based on an extension of the Johansen’s yield equations to fire conditions, including a model for the variation of the embedment strength with temperature. [ABSTRACT FROM AUTHOR]

Thermal treatment is one of environmental friendly wood modification processes, developed in order to improve wood’s natural durability and dimensional stability. Beside wood species, mainly isothermal temperature of heat-treatment and process duration affect these properties, which also correlate with the mass losses caused by the treatment. However, there is a lack of suitable external quality control methods. In this work thermogravimetry as a potential method for determining the degree of thermal modification is presented. Several calibration curves, representing the mass losses in a certain temperature range (the values obtained from the TG curves) compared to weight losses caused by previous heat-treatment (known values), were established for spruce wood samples modified at different isothermal temperatures (from 170 to 220 °C). Linear plot and good correlation factors ( R2 = 0.95 and 0.96) were obtained for the TG mass losses from 130 to 280 °C and from 130 to 300 °C, both under nitrogen atmosphere. The predominant cause of mass loss in this temperature region was depolymerisation and thermal decomposition of hemicelluloses residues. Lower correlation factors were obtained under the air atmosphere and in the wider temperature range, respectively. [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]

We propose a physicomathematical model for the evaluation of the temperature, humidity, and pressure of an air-vapor mixture and use this model to determine the stresses and strains formed in the process of pressing of a particleboard under the action of variable pressure. The adequacy of the results of numerical realization of the model to the experimental data is demonstrated. The influence of the principal thermal parameters on the stresses and strains is analyzed for different stages of pressing. [ABSTRACT FROM AUTHOR]