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Thermal modification processes are environmentally friendly methods used to improve certain properties of wood. Currently, wood from thinning of young plantations of Nothofagus alpina (raulí) in Chile is being evaluated to obtain value before the plantation has reached maturity. The objective of this paper was to assess selected properties of thermally modified wood of young (14- to 25-years-old) N. alpina wood that comes from thinning of two sites with intensive silviculture and one similar to a secondary growth forest. To achieve this, non-destructive tests were carried out to measure some chemical-crystalline characteristics, as well as physical and mechanical properties; the differences between the 25%, 50%, and 75% distance from pith to the bark in each site was studied. The modification temperatures used were 170, 190, and 210 ℃. The results show that thinning wood from N. alpina can be thermally modified with favorable results, thus presenting an option to obtain value while the plantation reaches maturity, particularly the thinning wood from the intensive forestry regimes, which presented most homogeneous results, especially at the modification temperature of 190 ℃. [ABSTRACT FROM AUTHOR]

Silver fir (Abies alba L.) wood samples were charred on one surface using an enhanced version of the traditional Japanese Yakisugi method. The 15 charred boards obtained from five charring chimneys were divided into three different zones and investigated for their physical properties. The density profile, water absorption after 24 h of water submersion, and Brinell hardness were analyzed. In general, the temperature-time regime, which causes inside surface carbonization, was more evident at the bottom than at the top of the chimney. The density profile of the specimens revealed that the surface charring treatment decreased the surface density of the wood significantly. A gradient was visible from 383 kg/m² at the bottom to 424 kg/m² at the top. Water absorption measurements showed that a thicker carbonized layer could take up more water as a result of increased porosity. While 3,684 g/m² were absorbed at the bottom, the top accounted for only 2,533 g/m². Furthermore, with increasing thickness of the charred layer, the hardness gradually decreased. The average of the charred specimens reached only 3.2% of the hardness of the uncharred back side of the specimens.

Silver fir (Abies alba L.) wood samples were charred on one surface using an enhanced version of the traditional Japanese Yakisugi method. The 15 charred boards obtained from five charring chimneys were divided into three different zones and investigated for their physical properties. The density profile, water absorption after 24 h of water submersion, and Brinell hardness were analyzed. In general, the temperature-time regime, which causes inside surface carbonization, was more evident at the bottom than at the top of the chimney. The density profile of the specimens revealed that the surface charring treatment decreased the surface density of the wood significantly. A gradient was visible from 383 kg/m² at the bottom to 424 kg/m² at the top. Water absorption measurements showed that a thicker carbonized layer could take up more water as a result of increased porosity. While 3,684 g/m² were absorbed at the bottom, the top accounted for only 2,533 g/m². Furthermore, with increasing thickness of the charred layer, the hardness gradually decreased. The average of the charred specimens reached only 3.2% of the hardness of the uncharred back side of the specimens. [ABSTRACT FROM AUTHOR]

The aim of this work was to better understand the ignition method of timber charring in order to improve the industrial process. Three silver fir boards were tied together to make a triangular prism, which acted as a chimney. To start the charring process, the traditional Yakisugi method uses an ignitor paper ball. This ignitor paper ball was in this research replaced with a gas burner. The gas burner supplies the required energy in an even level and provides airflow in the upward direction. The surface temperature of the samples increased from 10 to 500 °C in approximately 40 to 80 s at all recorded positions, which is considerably faster than when using a traditional method. The thickness of the charred layer and the resulting cupping effect were investigated as an indicator of the quality of the process. The charred layer produced by the gas burner method was not as thick as was achieved with the traditional method, which can be attributed to a shorter charring time. Approximately half the specimens showed cupping to the charred side, which may be related not only to a shorter charring time than previous studies, but also to the annual ring orientation of the timber. Further research should be performed on the charred layer thickness and cupping to define all relevant parameters. [ABSTRACT FROM AUTHOR]

A densification method is proposed and developed to improve the mechanical properties of Uludağ fir (Abies bornmüelleriana Mattf.) and black poplar (Populus nigra L.) woods. The method, called Thermo-VibroMechanic® densification, is derived from the hypothesis that the vibration added to the traditional thermo-mechanical densification process can cause the wood cell walls to interlock with each other at the micro-level via the friction effect. In addition, it aims to remove the cell cavities under lower pressure compared to other densification methods via the shaking effect. To test this hypothesis, the samples, obtained in both the radial and tangential directions, were pre-treated with wood stain and preservative before undergoing the densification process. Thermo-Vibro-Mechanic® densification was performed at varying temperatures (100, 120, and 140 °C), pressures (0.60, 1.00, and 1.40 MPa), and durations (20, 60, and 100 s). The changes in the values of the bending strength, modulus of elasticity, and compression strength parallel to the grain in the radial and tangential directions were determined accordingly. The results showed that the Thermo-Vibro-Mechanic® densification process increased the bending strength and modulus of elasticity values up to 50%, while the compression strength reached 67% higher than the untreated wood. [ABSTRACT FROM AUTHOR]

Tannins and their toxic effects against various decay organisms have been interrelated for centuries. As natural products have gained more interest, waste from several production fields abundant in tannins has yielded promising components for wood preservation. In this work, the main approach was to split condensed tannins into smaller fractions by chemical hydrolysis and evaluate their suitability for beech wood impregnation. Commercial extract from black wattle was treated with mineral acid of low concentration. The volatile hydrochloric acid was completely removed after reaction by evaporation in the course of freeze-drying. The modified extract was then applied as aqueous solution into beech wood. The water resistance of the modified beech wood was not increased significantly, and scanning electron microscopy (SEM) showed no evidence of tannin successful bonding within wood cells. Nevertheless, after strong leaching cycles, part of the extract accumulated in fibers. Moreover, lyophilization was found to be a suitable technique to eliminate volatile acids from temperature-sensitive extracts, such as tannins. These findings could help in the development of water-borne tannin formulations for wood protection, while using phlobaphene formation as a potential natural pathway of tannin autocondensation. [ABSTRACT FROM AUTHOR]

To improve the appearance of the black locust wood under heat treatment, ammonia (AM), acetic acid (AA), and ammonium acetate (AMA) were adsorbed into the black locust wood flour, with or without aluminum sulfate octadecahydrate (ASO). The color parameters (CIE L*a*b*) of the black locust wood flour treated with different conditions were measured. Diffuse reflectance ultraviolet-visible spectroscopy (DRUV-Vis) and the attenuated total reflection/Fourier transform infrared spectroscopy (ATR-FTIR) were conducted to reveal the changes of the chromophore systems. X-ray photoelectron spectroscopy (XPS) was used to demonstrate the extreme valence of the atomic content and the occurrence of a coordination reaction. The color of the wood flour became reddish after the treatment with AMA+ASO. There was an increase in carbonyl structure and carboxyl structure of the wood flour treated with AMA and ASO. [ABSTRACT FROM AUTHOR]

Tungsten trioxide (WO3) nanosheets were deposited onto a wood surface by a solvothermal synthesis method using temperatures between 90 and 120°C. These WO3 nanosheets were used to improve the color, as well as to enhance the photochromic characteristics and ultraviolet aging resistance of the wood. The results indicate that the WO3 nanosheets on the wood’s surface were affected by the treatment temperature. The formed nanosheets included nanoparticles and rod-shaped structures, which are highly crystallized. Different structures were generated in the nanosheets, which affected their functionality. The modified wood not only exhibited photochromic phenomena when excited by ultraviolet radiation, but also demonstrated resistance against ultraviolet light aging. [ABSTRACT FROM AUTHOR]

An eco-friendly agent mainly consisting of activated glucose (AG) and citric acid (CA) was investigated for its potential wood modification applications. Scots pine (Pinus sylvestris L.) sapwood was treated with AG and CA both individually and in combination. The treatments with the combined agent resulted in an increase in the weight percent gain and decrease in the leaching ratio, which suggested a synergy between the two components for their fixation in wood. The dynamic vapor sorption behavior indicated an increased sorption at a higher AG concentration. Compared with the AG treatment, the CA treatment more effectively improved the dimensional stability of the wood. The modulus of elasticity was not influenced by the treatments, and the modulus of rupture was slightly reduced. Incorporation of AG in the CA inhibited the decrease in impact strength of wood compared to treatment with CA alone, which was a result of reduced crosslinking from the CA within the wood matrix. Fourier transform infrared (FTIR) spectroscopy revealed an enhanced absorbance, indicating development of ester bonds due to the treatment. [ABSTRACT FROM AUTHOR]

A broader utilization of wood can be achieved by eliminating its drawbacks such as low dimensional stability with changing moisture content and low durability against various bio-organisms. Heartwood formation is nature's solution that functions through biosynthesis and accumulation of some phenolic compounds in the cell walls, leading to more durable and stable wood. In this study, a natural flavonoid molecule, chrysin, was used to improve Scots pine wood properties. Hydrophobic chrysin was impregnated into wood after a pre-treatment. The chrysin modification reduced the water uptake of the wood cell walls by up to 33% and increased the dimensional stability of the Scots pine by up to 30%. Infrared spectroscopic analysis revealed the chemical characterization of the bioinspired modification. In contrast to the many modification methods that establish covalent bonds between hydroxyl groups of wood polymers, chrysin was bulked into wood cell walls and stabilized by intermolecular interactions. [ABSTRACT FROM AUTHOR]

Scots pine and white poplar were modified with melamine formaldehyde (MF) and melamine-urea formaldehyde (MUF) resins to improve their physical and mechanical properties. Impregnation was conducted at 4 bar pressure for 30 or 60 min, and the samples were cured at a temperature of 150 °C for 40 min in an oven. The density, equilibrium moisture content, weight percent gain, bulking effect, water uptake, volumetric swelling, anti-swelling efficiency, modulus of rupture, modulus of elasticity, compression strength parallel to the grain, and Brinell hardness of the modified wood were determined. The anti-swelling efficiencies were 57% and 74% in Scots pine and white poplar, respectively, using the melamine formaldehyde resin. Modification of white poplar with melamine-urea formaldehyde increased the modulus of elasticity, compression strength, and Brinell hardness considerably. Both resins were successful at improving the physical and mechanical properties of Scots pine and white poplar woods.

Four fast-growing wood species were treated, including two hardwood species and two softwood species, with either furfurylation or acetylation for comparison and analysis. The properties of the resultant woods, including weight percent gain, bulking effect, leach rate, anti-swelling efficiency (ASE), and color changes, were compared comprehensively. The effects of wood species on modification efficiency were also evaluated by morphological analysis. The results indicated that the species of wood had little effect on successful acetylation, but that wood species with more open pits and loose and ordered structures were best suited for furfurylation. Both types of modification resulted in wood samples with more uniform colors than untreated samples. Furfurylation caused considerable color changes in all of the wood samples; acetylation resulted in wood samples slightly lighter in color (lower ΔE* values). The differences in ΔE* values among the four wood species were primarily due to the natural differences in the color of the woods.

Microwave and conventional acetylation of wood was carried out to determine its efficacy on the material properties. Beech (Fagus sylvatica L.) and poplar (Populus hybrids) samples with dimensions 14 mm × 14 mm × 14 mm were impregnated using acetic anhydride, and chemical reactions were initiated by microwave and conventional heating. The microwave acetylation process was carried out using laboratory equipment at a frequency of 2.45 GHz in several testing modes to reduce time of the reaction. The uptake of substance, equilibrium moisture content, wood swelling, and dimensional stability were determined in order to evaluate the efficacy and degree of acetylation. Both microwave and conventional heating positively affected the selected material properties. The results showed that no significant differences were found between microwave and conventional heating; therefore, microwave heating can be used as a valid replacement in the acetylation process. Microwave power of 2 kW and 0.1 m∙min-1 conveyor speed were the optimum conditions for microwave acetylation. These process parameters resulted in 39.4% ASE T and 35.2% ASE R for beech and 38.0% ASE T and 16.3% ASE R for poplar samples. This work provides insight into the details of wood acetylation using microwave heating.

Thermally modified wood has high dimensional stability and biological durability.But if the process parameters of thermal modification are not appropriate, then there will be a decline in the physical properties of wood.A neural network algorithm was employed in this study to establish the relationship between the process parameters of high-temperature and high-pressure thermal modification and the mechanical properties of the wood. Three important parameters: temperature, relative humidity, and treatment time, were considered as the inputs to the neural network. Back propagation (BP) neural network and radial basis function (RBF) neural network models for prediction were built and compared. The comparison showed that the RBF neural network model had advantages in network structure, convergence speed, and generalization capacity. On this basis, the inverse model, reflecting the relationship between the process parameters and the mechanical properties of wood, was established. Given the desired mechanical properties of the wood, the thermal modification process parameters could be inversely optimized and predicted. The results indicated that the model has good learning ability and generalization capacity. This is of great importance for the theoretical and applicational studies of the thermal modification of wood.

This study investigated the feasibility of using an electron beam (EB) process to cure chemically impregnated wood products. Maple wood planks were impregnated with the low-viscosity resins 1,6 hexanediol dimethacrylate (HDDA) and trimethylolpropane trimethacrylate (TMPTA). The addition of nanoparticles into the formulation was also studied. The impregnated wood was then cured by EB irradiation. The EB curing method utilizes highly energetic electrons at a controlled energy level to polymerize and cross-link the polymeric materials. The thermal analysis results of differential scanning calorimetry (DSC) confirmed that the curing of chemically impregnated wood by electron beam radiation was validated. Polymerization exotherms were observed for the neat acrylate resin and formulations of acrylate/nanoparticles impregnated maple samples. No polymerization exothermal peaks were observed for both EB-cured impregnated maple and control maple samples, confirming that EB irradiation can serve as an efficient curing method to polymerize acrylate-impregnated wood products. The surface hardness of the EB-cured impregnated maple wood was improved up to 200%.

Samples of Scotch pine sapwood were treated with epoxidized linseed and soybean oils via an empty cell process to improve the hydrophobic properties of wood. Boric acid was included to introduce fungicidal properties into the oils. Two retention levels (80 to 140 kg/m3 and 170 to 270 kg/m3) were targeted for oil treatments. Both an empty cell method and emulsion techniques were used to combine epoxidized oils and boric acid in a one-step treatment. Iodine number changes, Fourier transform infrared spectroscopy (FTIR), water absorption (WA), anti-swelling efficiency (ASE), and scanning electronic microscopy (SEM) analyses were used to characterize the wood after treatment. High iodine number changes that indicated a reduction the amount of unsaturated double bonds were determined. The FTIR analysis of epoxidized oils revealed a peak at 820 cm-1, which indicated that epoxide moieties (C-O-C) were present. All of the oil treatments resulted in statistically significant lower water absorptions than the control sample. The lowest water absorption values were obtained from wood treated with epoxidized oils. The highest ASE result (70%) was observed on samples treated with epoxidized soybean oil at low retention (108 kg/m3). It was also determined that most of the latewood tracheids were filled with oils when compared to the earlywood tracheids. [ABSTRACT FROM AUTHOR]

Wood is a renewable and environmental friendly material, but its low dimensional stability characteristics limit its applications. In this study, wax mixed with dimethyl silicone oil was used to enhance the dimensional stability under heat treatment. Samples were heated at 120 °C under 3 impregnation conditions (wax, wax + 20% dimethyl silicone oil, and wax + 40% dimethyl silicone oil) for 3 and 6 h respectively. After treatment the effects of combination pretreatment on wood weight gain percentage (WPG), tangential, radial and volume swelling coefficients (TS, RS, VS), distribution of impregnation liquid, and the types of functional groups of African Padauk (Pterocarpus soyauxii) were evaluated. The results showed that impregnation improved the dimensional stability of wood to a certain extent; moreover, the addition of dimethyl silicone oil improved the modification effect. Furthermore, the VS reduced to 0.66 (±0.28)% in the treatment of wax + 20% dimethyl silicone oil for 6 h. The impregnation liquid mainly adhered to the walls of vessels and ray cells. The hydroxyl absorption intensity of the impregnated groups was lower than that of the control group. [ABSTRACT FROM AUTHOR]

Wood/polymer nanocomposites were prepared by vacuum impregnation of furfuryl alcohol (FA) and nano-SiO2 into fast-growing poplar wood. The nano-SiO2 was mixed with FA solution, followed by in-situ polymerization of FA. The properties of nanocomposites and the effects of nanoparticles on these properties were investigated. Wood physico-mechanical properties, such as dimensional stability, density, water uptake, and surface hardness, were significantly improved. Moreover, the addition of nano-SiO2 improved the surface hardness and dimensional stability of wood and kept the excellent properties of FA-treated wood. Thermogravimetric analysis indicated that the effect of nano-SiO2 on thermostability was hindered. X-ray photoelectron spectroscopy and scanning electron microscopy with energy-dispersive X-ray spectroscopy showed that nano-SiO2 was successfully incorporated into wood via the action of FA, and diffused into the wood lumen and cell wall. X-ray diffraction results indicated the weakening of the crystallinity in the treated wood was due to the polymerization of FA.

Treatment of poplar wood using glyoxal as a non-formaldehyde cross-linking reagent was investigated. Cross-linking occurred with glyoxal in the presence of the catalysts aluminum sulfate, magnesium chloride, zinc nitrate, maleic anhydride, ammonium dihydrogen phosphate, and ammonium persulfate. Ammonium persulfate was found to be the most effective single catalyst, which may be due to the synergistic catalytic effect of NH4+ and S2O82-, Further, catalyst combinations produced higher overall performance in comparison with the single one, and the optimal combination was maleic anhydride and ammonium persulfate. An increase in ammonium persulfate improved wood dimensional stability and anti-leaching properties, but weakened the hydrophobicity and deepened the colour of the modified wood. Considering the balance between anti-swelling efficiency, leachability, and water uptake, the optimum catalyst concentration was 2%. Although the addition of sodium hydroxide into a glyoxal solution can reduce wood discoloration, it may also reduce the modification efficiency.

Molds in wet and warm environments often attack surfaces of products made from beech and other less or moderately durable woods. This paper presents the effects of the physical modification of beech wood with a CO2 laser having a constant power output of 45 W, using eight radiation doses from 7.8 to 75 J/cm2. Variations in laser activations created a scale of color changes in surfaces of beech wood determined in the CIE L*a*b* system, ranging from an apparently unaffected to totally dark due to carbonization effects. The surfaces of beech samples modified by laser were subsequently infected with the molds Aspergillus niger and Penicillium brevicompactum, and their growth on the top surfaces of beech samples was evaluated according to the standard STN 49 0604 (1980). The modified surfaces of beech wood exposed to higher CO2 laser powerful effects (i.e., radiation doses 25 J/cm2 and more) obtained evidently higher resistance to Aspergillus niger, but their resistance to Penicillium brevicompactum changed only minimally. [ABSTRACT FROM AUTHOR]

Scots pine and white poplar were modified with melamine formaldehyde (MF) and melamine-urea formaldehyde (MUF) resins to improve their physical and mechanical properties. Impregnation was conducted at 4 bar pressure for 30 or 60 min, and the samples were cured at a temperature of 150 °C for 40 min in an oven. The density, equilibrium moisture content, weight percent gain, bulking effect, water uptake, volumetric swelling, antiswelling efficiency, modulus of rupture, modulus of elasticity, compression strength parallel to the grain, and Brinell hardness of the modified wood were determined. The anti-swelling efficiencies were 57% and 74% in Scots pine and white poplar, respectively, using the melamine formaldehyde resin. Modification of white poplar with melamine-urea formaldehyde increased the modulus of elasticity, compression strength, and Brinell hardness considerably. Both resins were successful at improving the physical and mechanical properties of Scots pine and white poplar woods. [ABSTRACT FROM AUTHOR]

A process for the chemical modification of Chinese fir with alkyl ketene dimer (AKD) was studied. The hydrophobicity of the resulting products was evaluated by characterization of the equilibrium moisture content, water-surface contact angle, water absorption coefficient, and anti-swelling efficiency. The results indicated that when 5% AKD solution was used, the modified wood generally showed good hydrophobicity and improved dimensional stability. The result of boiling water and hexane extraction tests showed that the modified fir possessed very stable hydrophobicity.

Previous preliminary studies showed good efficacy of treatments based on a mixture of siloxane materials, functionalized with amino groups and coupled with copper, against the brown rot fungus Coniophora puteana (Palanti et al. 2011). In the present work, a one-step impregnation was performed on two sets of samples differing in size, in order to verify and compare the homogeneity of treatments. Leaching and resistance against brown rot and white rot fungi were also tested according to European standards EN 84 and EN 113, respectively. Furthermore, an accelerated test of efficacy against fungal decay was also used for determining the treatment efficacy. The obtained results made it possible to validate the findings of the preliminary study concerning resistance of the treated wood against C. puteana, while extending them to the white rot fungus Trametes versicolor. In contrast, no protection was conferred by the treatment against the copper-tolerant fungus Poria placenta.

In this work, the effect of oil heat treatment (OHT) on the swelling properties and changes in the rate of moisture uptake of poplar wood (Populus × euramericana cv. Pannónia) were investigated. Eighteen different treatments (combinations of three vegetable oils, two temperatures, and three durations) were studied. The results showed that OHT decreases the equilibrium moisture content (EMC) and the swelling of poplar wood. The degree of swelling and the EMC are influenced by both the duration and temperature of treatment. With an increase in duration and temperature, the EMC decreased. Consequently, the anti-swelling efficiency (ASE) increased. OHT wood adsorbs less moisture than natural wood, but it reaches a maximum – EMC at the momentary climate – at the same time under all the investigated treatments. The moisture uptake is fastest in the beginning and thereafter it slows significantly. Decreasing the moisture uptake by OHT wood is due to the decreasing of its water storage capacity.

Thermal treatment is a suitable method for improving the quality of wood types like spruce, beech or poplar, and thus to open up new fields of application that used to be limited to tropical woods or woods treated with timber preservatives. These thermally treated woods are characterized by a typical odor caused by degradation products of miscellaneous wood components. The characterization and removal of those odorous substances were investigated using chromatographic and spectroscopic methods. Headspace gas chromatography (GC) in combination with solid-phase microextraction (SPME) was used for a qualitative analysis of volatile wood emissions, and the detectable volatiles were compared before and after solvent extraction. Wood solvent extractives were investigated by means of gas chromatography/mass spectrometry and then evaluated in terms of changes in composition caused by the thermal treatment process.

Microwave and conventional acetylation of wood was carried out to determine its efficacy on the material properties. Beech (Fagus sylvatica L.) and poplar (Populus hybrids) samples with dimensions 14 mm ? 14 mm ? 14 mm were impregnated using acetic anhydride, and chemical reactions were initiated by microwave and conventional heating. The microwave acetylation process was carried out using laboratory equipment at a frequency of 2.45 GHz in several testing modes to reduce time of the reaction. The uptake of substance, equilibrium moisture content, wood swelling, and dimensional stability were determined in order to evaluate the efficacy and degree of acetylation. Both microwave and conventional heating positively affected the selected material properties. The results showed that no significant differences were found between microwave and conventional heating; therefore, microwave heating can be used as a valid replacement in the acetylation process. Microwave power of 2 kW and 0.1 m·min-1 conveyor speed were the optimum conditions for microwave acetylation. These process parameters resulted in 39.4% ASET and 35.2% ASER for beech and 38.0% ASET and 16.3% ASER for poplar samples. This work provides insight into the details of wood acetylation using microwave heating. [ABSTRACT FROM AUTHOR]

Wood/polymer nanocomposites were prepared by vacuum impregnation of furfuryl alcohol (FA) and nano-SiO2 into fast-growing poplar wood. The nano-SiO2 was mixed with FA solution, followed by in-situ polymerization of FA. The properties of nanocomposites and the effects of nanoparticles on these properties were investigated. Wood physico-mechanical properties, such as dimensional stability, density, water uptake, and surface hardness, were significantly improved. Moreover, the addition of nano-SiO2 improved the surface hardness and dimensional stability of wood and kept the excellent properties of FA-treated wood. Thermogravimetric analysis indicated that the effect of nano-SiO2 on thermostability was hindered. X-ray photoelectron spectroscopy and scanning electron microscopy with energy-dispersive X-ray spectroscopy showed that nano-SiO2 was successfully incorporated into wood via the action of FA, and diffused into the wood lumen and cell wall. X-ray diffraction results indicated the weakening of the crystallinity in the treated wood was due to the polymerization of FA. [ABSTRACT FROM AUTHOR]

Wood/polymer nanocomposites were prepared by vacuum impregnation of furfuryl alcohol (FA) and nano-SiO2 into fast-growing poplar wood. The nano-SiO2 was mixed with FA solution, followed by in-situ polymerization of FA. The properties of nanocomposites and the effects of nanoparticles on these properties were investigated. Wood physico-mechanical properties, such as dimensional stability, density, water uptake, and surface hardness, were significantly improved. Moreover, the addition of nano-SiO2 improved the surface hardness and dimensional stability of wood and kept the excellent properties of FA-treated wood. Thermogravimetric analysis indicated that the effect of nano-SiO2 on thermostability was hindered. X-ray photoelectron spectroscopy and scanning electron microscopy with energy-dispersive X-ray spectroscopy showed that nano-SiO2 was successfully incorporated into wood via the action of FA, and diffused into the wood lumen and cell wall. X-ray diffraction results indicated the weakening of the crystallinity in the treated wood was due to the polymerization of FA. [ABSTRACT FROM AUTHOR]

1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) was used to enhance the dimensional stability, fungal resistance, and weathering of wood. The mechanical strength of wood treated with DMDHEU and different catalysts at different treating temperatures was studied. With increasing temperature, the modulus of rupture (MOR) and modulus of elasticity (MOE) of DMDHEU-treated wood first increased and then decreased. Different catalysts exhibited different effects on the MOR and MOE. In the context of SEM, EDAX, and FTIR analyses, the mechanism of strength loss resulting from the treatment with DMDHEU is discussed. In addition, the relationship between strength and pore size distribution determined by DSC was studied. The filling effect of the cured DMDHEU in wood pores reduced the pore size of the samples and may provide mechanical support to the cell wall, which prevents strength loss of the treated wood when the curing temperature is relatively low (90°C). But at higher curing temperatures (150°C), the mechanical strength properties of DMDHEU-treated wood decreased greatly. [ABSTRACT FROM AUTHOR]

Previous preliminary studies showed good efficacy of treatments based on a mixture of siloxane materials, functionalized with amino groups and coupled with copper, against the brown rot fungus Coniophora puteana (Palanti et al. 2011). In the present work, a one-step impregnation was performed on two sets of samples differing in size, in order to verify and compare the homogeneity of treatments. Leaching and resistance against brown rot and white rot fungi were also tested according to European standards EN 84 and EN 113, respectively. Furthermore, an accelerated test of efficacy against fungal decay was also used for determining the treatment efficacy. The obtained results made it possible to validate the findings of the preliminary study concerning resistance of the treated wood against C. puteana, while extending them to the white rot fungus Trametes versicolor. In contrast, no protection was conferred by the treatment against the copper-tolerant fungus Poria placenta. [ABSTRACT FROM AUTHOR]

In this work, the effect of oil heat treatment (OHT) on the swelling properties and changes in the rate of moisture uptake of poplar wood (Populus x euramericana cv. Pannónia) were investigated. Eighteen different treatments (combinations of three vegetable oils, two temperatures, and three durations) were studied. The results showed that OHT decreases the equilibrium moisture content (EMC) and the swelling of poplar wood. The degree of swelling and the EMC are influenced by both the duration and temperature of treatment. With an increase in duration and temperature, the EMC decreased. Consequently, the anti-swelling efficiency (ASE) increased. OHT wood adsorbs less moisture than natural wood, but it reaches a maximum - EMC at the momentary climate - at the same time under all the investigated treatments. The moisture uptake is fastest in the beginning and thereafter it slows significantly. Decreasing the moisture uptake by OHT wood is due to the decreasing of its water storage capacity. [ABSTRACT FROM AUTHOR]

Wood modification is a generic term describing the application of chemical, physical, or biological methods to alter the properties of the material. The aim is to get better performance from the wood, resulting in improvements in dimensional stability, decay resistance, weathering resistance, etc. It is essential that the modified wood is non-toxic in service and that disposal at the end of life does not result in the generation of any toxic residues. Over the past five years there have been significant developments in wood modification technologies, especially in the commercial sector. This technology is here to stay.