Resistance Of Wood Research Articles

Dimensional Stability, Color Change, and Durability of Boron-MMA Treated Red Jabon (Antochephalus macrophyllus) Wood

Boron compound had many advantages as wood preservative, but it was prone to leaching. Improving boron preservation was required to extend the service life of fast growing and low durability red jabon (Antochephalus macrophyllus) hardwood. This study aimed to evaluate the dimensional stability, color change and durability of modified red jabon wood by double impregnation with boron and methyl methacrylate (MMA) and heat treatment. Impregnation I used boric acid or borax, and impregnation II used MMA, while heat treatment used temperatures of 90 °C or 180 °C for 4 hours. The dimensional stability, leachability, water absorption, color change and decay resistance of modified red jabon wood were tested. The results showed that MMA impregnation increased the dimensional stability of red jabon wood, while the leaching and water absorption in the wood significantly reduced. Heating at 180 °C caused less water absorption and higher dimensional stability of the wood than that of heating at 90 °C. Impregnation with boric acid and MMA followed by heating at 90 °C resulted in the highest wood ASE, 89.9%. The color change (ΔE*) of wood increased significantly after MMA impregnation and heating at 180 °C. Boric acid impregnation caused more resistant wood than borax impregnation against decay fungi and termites. Impregnation with boric acid and MMA followed with heating at 180 °C increased significantly the wood resistance against decay fungi and termites.

Determination of the laws of thermal resistance of wood in application of fire-retardant fabric coatings

The creation of environmentally safe fire-retardant materials for wooden building structures will allow influencing the processes of heat resistance and physicochemical properties of the protective coating during its service life. Therefore, there is a need to study the conditions for forming a barrier to thermal conductivity and determine a mechanism of inhibiting heat transfer to the material. In this regard, a mathematical model of the thermal conductivity process when using fire-retardant fabric as a coating is developed, the solution of which allows obtaining changes in the thermal conductivity of the material. According to experimental data, it is calculated that the thermal conductivity coefficient during fire protection in the temperature range from 0 to 110 °C increases due to water evaporation and then gradually decreases to 0.25 W/(m∙°С), which corresponds to the value of coked foam. It is proved that the process of temperature inhibition consists in the formation of soot-like products that insulate the wooden structure. This made it possible to determine the conditions of fire protection of wood, formation of a barrier to thermal conductivity using fire-retardant fabric. Experimental studies confirmed that the wood sample with fire-retardant fabric withstood the temperature effect, namely, under the influence of the heat flux, the coating swelled, heat insulation continued for 900 s. Estimation of the maximum possible temperature penetration through the coating is carried out. It is found that when creating the sample surface temperature, which significantly exceeded the ignition temperature of wood, the temperature under the fabric did not reach the ignition temperature, and on the unheated surface it did not exceed 100 °C. Thus, there are reasons to argue about the possibility of directed control of the processes of wood fire protection using fire-retardant coatings capable of forming a protective layer on the material surface, which reduces the burnout rate of wood

Scratch resistance of PEG-impregnated green wood: a method for evaluation of swollen wood properties

This work proposes an experimental approach to study the scratch resistance of green wood under the effect of polyethylene glycol (PEG) impregnation. To this end, small-scale green spruce samples are stabilized against water by using the technique of PEG impregnation to prevent water to seep out of the wood during experimental tests. Scratches are performed in the radial-longitudinal and tangential-longitudinal planes of cubic wood samples by using two different indenter tips under constant and progressive normal loads. Scratch testing has previously been used mainly to characterize the abrasion resistance of coatings. Since PEG simulates the swelling effect of water in wood, this paper shows that the scratch tests on PEG-impregnated green wood can be adopted as a simple technique to understand the scratch resistance in swollen wood and the related mechanisms. The scratch test results, quantified in terms of frictional forces and permanent residual depths, reveal that the scratch resistance of wood samples depends on their PEG concentration and density, as well as on the indenter tip size and material, and on the normal force and direction during scratching. Due to the lack of literature on the scratch tests of wood, the results presented in this paper will serve as a scientific reference for future studies on the scratch resistance of untreated or treated dry wood and other wood-based products.

Enhancing weathering resistance of wood by using bark extractives as natural photostabilizers in polyurethane-acrylate coating

In this study, Chinese fir bark was extracted separately by three solvents including sodium hydroxide, 95% ethanol, and hot water, and the obtained extractives were labelled as NaE, EtE, and HWE correspondingly. The ultraviolet (UV) absorption and antioxidation activity of those bark extractives were confirmed. The aim of this study was to improve the photostabilization of polyurethane-acrylate (PUA) coating by incorporating bark extractives as photostabilizers. Then, the modified coatings were used to coat Scots pine wood samples in order to enhance their weathering resistance. During 960 h of accelerated UV weathering, the changes in wood surface color, gloss, morphology, and surface chemistry were investigated. Meanwhile, the photostabilization mechanisms of bark extractives were also discussed. The results showed that (1) the free radical scavenging ability of extractives was related with their total phenolic contents; (2) wood protected by PUA/EtE coating experienced the least severe surface deterioration and photodegradation during the whole weathering process; (3) the photosatbilization effect of EtE mainly resulted from its phenolic compounds, which transferred into ketones and quniones after weathering.

The Possibility of Propolis Extract Application in Wood Protection

Nowadays, there is a growing interest in extending the service life of wood and wood products by applying natural substances that are harmless to humans and the environment. In this paper, propolis was used as an eco-friendly wood preservative. The aim of this study was to determine the resistance of Scots pine wood treated with the propolis extract against brown-rot fungus Coniophora puteana. The wood biodegradation was assessed by gravimetric method, as well as by the analysis of ergosterol concentration in decayed wood and by the determination of changes in the wood structure by means of Fourier transform infrared spectroscopy. The results indicated that the impregnation of wood with propolis extract above 12% concentration limited fungal decay. The mass loss of wood treated with 18.9% propolis extract was 2.3% and was over 21 times lower than that for untreated wood. The analysis of ergosterol content and the changes in wood structure also confirmed that the propolis extract above 12% concentration protected wood against decay caused by C. puteana. Moreover, the propolis extract used in wood impregnation was rich in phenolic compounds, mainly chrysin, pinocembrin and galangin, which possess antimicrobial activity. The obtained results indicate that the extract of Polish propolis can be a promising natural wood preservative, safe for humans and the natural environment.

Facile Construction of Superhydrophobic Surfaces by Coating Fluoroalkylsilane/Silica Composite on a Modified Hierarchical Structure of Wood.

Constructing superhydrophobic surfaces by simple and low-cost methods remains a challenge in achieving the large-scale commercial application of superhydrophobic materials. Herein, a facile two-step process is presented to produce a self-healing superhydrophobic surface on wood to improve water and mildew resistance. In this process, the natural hierarchical structure of wood is firstly modified by sanding with sandpaper to obtain an appropriate micro/nano composite structure on the surface, then a fluoroalkylsilane/silica composite suspension is cast and dried on the wood surface to produce the superhydrophobic surface. Due to the full use of the natural hierarchical structure of wood, the whole process does not need complicated equipment or complex procedures to construct the micro/nano composite structure. Moreover, only a very low content of inorganic matter is needed to achieve superhydrophobicity. Encouragingly, the as-obtained superhydrophobic surface exhibits good resistance to abrasion. The superhydrophobicity can still be maintained after 45 abrasion cycles under the pressure of 3.5 KPa and this surface can spontaneously recover its superhydrophobicity at room temperature by self-healing upon damage. Moreover, its self-healing ability can be restored by spraying or casting the fluoroalkylsilane/silica composite suspension onto this surface to replenish the depleted healing agents. When used for wood protection, this superhydrophobic surface greatly improves the water and mildew resistance of wood, thereby prolonging the service life of wood-based materials.

Study of maximum frost resistance of cherry scion/stock combinations

The research was carried out on the basis of the laboratory of stability of physiology of fruit plants at All-Russian research Institute of Breeding of Fruit Crops in 2017-2018. The object of research was the scion/stock combinations of Novella and Turgenevka cherries/82987, C-2-180, 74332, 74340, 74336, 74324 breeding of the Institute. In the study of winter hardiness of cherry, special attention was paid to the ability of varieties to withstand low temperatures in mid-winter. The aim of the research was to study the maximum frost new scion/stock combinations of cherries by artificial freezing and selection of the hardiest of them. The results of the research noted that in the recovery period of organic dormancy in late December, when the cherry plants acquire the maximum hardened state, study scion/stock combinations were characterized by high resistance to frost of bark and wood of annual branches. They noted frost resistance of vegetative buds with reversible damage. Significant differences in the freezing vegetative buds, bark and wood between scion/stock combinations of sweet cherries are shown. Novella and Turgenevka cherry varieties on clonal rootstocks 74332, 74336, characterized by the greatest potential frost resistance of vegetative buds and tissues of annual branches at lower t= -35°C (winter hardiness component II) at the end of December. It is shown that all cherry scion/stock combinations have a low potential frost resistance of generative buds. After exposure to t= -35°C, living rudiments of flower buds preserved only in cherry scion/stock combinations Novella/74332, Turgenevka/74340, 74336 (from 4.0 to 15.4 %). According to the results of artificial freezing scion/stock combination Novella/74332 and Turgenevka / 74332, 74336 were revealed, which were characterized by the maximum frost resistance of generative, vegetative buds, bark and wood.

Termite resistance of pine wood treated with nano metal fluorides

Fluorides are well-known as wood preservatives. One of the limitations of fluoride-based wood preservatives is their high leachability. Alternative to current fluoride salts such as NaF used in wood protection are low water-soluble fluorides. However, impregnation of low water-soluble fluorides into wood poses a challenge. To address this challenge, low water-soluble fluorides like calcium fluoride (CaF2) and magnesium fluoride (MgF2) were synthesized as nanoparticles via the fluorolytic sol−gel synthesis and then impregnated into wood specimens. In this study, the toxicity of nano metal fluorides was assessed by termite mortality, mass loss and visual analysis of treated specimens after eight weeks of exposure to termites, Coptotermes formosanus. Nano metal fluorides with sol concentrations of 0.5 M and higher were found to be effective against termites resulting in 100% termite mortality and significantly inhibited termite feeding. Among the formulations tested, the least damage was found for specimens treated with combinations of CaF2 and MgF2 with an average mass loss less than 1% and visual rating of “1”. These results demonstrate the efficacy of low water-soluble nano metal fluorides to protect wood from termite attack.

Wood anatomy of Ceiba speciosa (A. St.-Hil.) Ravenna under urban pollution

AbstractUrban pollution is one of the current environmental problems which most threatens the human and environmental health. In a fast-changing world, trees stand out among the sessile organisms that withstand the variations imposed by the environment throughout their lifespan. Thus, trees have become important objects of study in the evaluation of phenological, physiological and/or morphological plasticity. Previous studies have demonstrated the impact of urban environment on cambium anatomy and dendrochronology ofCeiba speciosa(Malvaceae), a native species of the Atlantic Forest. In the present study, our objective is to evaluate the impact of the urban environment on wood structure and consequently on the hydraulic architecture ofCeiba speciosa. Wood samples were collected by a non-destructive method, processed and analyzed according to the usual techniques for plant anatomy. Samples were collected in two sites: the first, an important forest remnant of the Atlantic Forest, and the second next to Avenida Brasil, the largest avenue in Rio de Janeiro, the fourth largest city in Latin America. Trees showed plasticity in seven anatomical features and significant differences in wood structure between both groups studied. Urban trees have lower hydraulic conductivity, shorter vessels and fibres, and larger, more frequent rays. These features demonstrate that in stressful situations, such as those observed in urbanized environments,Ceiba speciosainvests in more safety for water transport and in lower wood resistance, with a trade-off between high production of cells of low energy cost and providing storage of water and metabolic products for unfavorable periods.

Improvement of water resistance and mechanical properties of fast-growing poplar with bio-based isobornyl methacrylate monomer

Fast-growing poplar has become an extensively planted fast-growing forest tree species because of its short plantation rotation, lightweight character, and strong adaptability. However, fast-growing poplar usually exhibits some disadvantageous properties, such as inferior mechanical properties, high hygroscopicity, and poor dimensional stability, which limits its applications to a great extent. Herein, a simple method for improving the water resistance and mechanical properties of fast-growing poplar wood using the biobased monomer isobornyl methacrylate (IBOMA) was investigated. Wood/PIBOMA composites were prepared by impregnating the wood matrix with IBOMA ethanol solution, and then the IBOMA in the wood matrix was heated to initiate in situ polymerization. Field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) were used to investigate the properties of fast-growing wood/PIBOMA composites. The results showed that the IBOMA successfully penetrated the wood structure and polymerized in the cell walls and cell lumens. Thereby, the water resistance and mechanical properties of the fast-growing poplar were effectively improved. In addition, the water uptake of the wood decreased from 168.3% to 35.8% after impregnation with the 90% IBOMA solution. The modulus of rupture (MOR), modulus of elasticity (MOE), and compression strength (CS) of the 90% wood/PIBOMA composites were increased by 82.7, 28.6, and 2.3%, respectively.

A study on the moisture performance of wood determined in laboratory and field trials

The present study analyses the moisture performance of nine wood species and wood-based materials determined in various laboratory and field trials to identify the method with the highest predictive power and determine the correlation between respective measurements. The moisture performance of wood and wood-based products has been recognised (besides inherent wood resistance) as the second most important parameter contributing to wood service life in above ground applications. Therefore, it is of great commercial importance to understand this phenomenon. In-service moisture monitoring trials can be unacceptably long, but on the other hand, they provide more realistic test conditions than laboratory tests. However, experiments in laboratory conditions enable a high level of reproducibility and are much faster than in-service tests. In order to assess the correlation between various tests, Pearson product moment correlation coefficients were calculated to determine the level of the strength of the linear relationship between the in-service and laboratory trials. Within this paper, it was attempted to identify laboratory methods suitable for quantification of moisture content during outdoor exposure.

Beech wood treated with polyglycerol succinate: a new effective method for its protection and stabilization

Abstract This paper deals with an original and non-biocidal chemical treatment consisting of a vacuum/pressure impregnation step of beech wood with a water-borne mixture made from heat-activated condensation of succinic anhydride (SA) and glycerol (G). Chemical structures of adducts were established using matrix-assisted laser desorption ionization time-of-flight mass spectroscopy (MALDI-TOF) investigations. Beech wood was impregnated and cured in order to induce in situ polymerization of glycerol/succinic adducts (GSA) in the cell walls, leading to the formation of polyglycerol succinate (PGS) polyester. Various treatment conditions were investigated depending on the duration (6–72 h) and curing temperature (103–160°C). Weight percent gains (WPGs) ranging between 40 and 60% were obtained. Attenuated total reflectance-middle infrared spectroscopy (ATR-MIR) and carbon-13 nuclear magnetic resonance (13C-NMR) spectroscopy confirmed polyester formation. A curing temperature of 160°C was found to be the best condition to totally avoid polymer leaching, and brought the anti-swelling efficiency (ASE) up to 64%. Decay resistance of PGS-treated wood against Trametes versicolor and Coniophora puteana was also strongly temperature and time dependent: performances fit with the EN113 standard requirements if a curing temperature of 160°C was applied.

Chemical constituents of tropical woods and resistance to the invasive drywood termite Cryptotermes brevis

AbstractWood‐feeding, nesting and production of secondary reproductives are key determinant traits of invasive species of drywood termites, and the West Indian drywood termite Cryptotermes brevis (Walker) is one of their major examples of worldwide concern as pest species of structural lumber, furniture and other wood products. The problem and losses by this species are determined by the prevailing wood characteristics. However, despite the current widespread occurrence of this species in the tropics, except Asia, tropical wood resistance and underlying mechanisms of resistance against this termite are scarcely known. Nonetheless, wood hardness and particularly wood density were recently recognized as important underlying traits for C. brevis resistance in tropical woods, but the chemical wood constituents were not considered. Here, we assessed tropical wood resistance to the invasive termite species C. brevis and tested the relevance of their holocellulose, lignin and (total) extractive contents preventing termite infestation. Free‐choice and no‐choice tests were carried out in parallel with wood chemical characterization. Resistance to the West Indian termite varied with wood species in terms of both colonization and consumption, but only under free‐choice testing because without choice, no significant difference was detected among wood species. Regardless, none of these traits were significantly correlated with wood resistance to C. brevis. Therefore, wood physical resistance, particularly wood density, seems the main recognized determinant of tropical wood resistance against the West Indian drywood termite. The pattern of termite movement on the surface of soft, mid and hard wood was also consistent with this conclusion.

Microstructure of thermally modified radiata pine wood

The thermal modification of wood is a potential alternative method for improving wood dimensional stability and increasing the resistance of wood to decay. However, during thermal modification, morphological changes occur within the microstructure of the cell, and these confer different properties to the wood. This study investigated the effects of the thermal modification process on the microstructure of radiata pine juvenile wood. Therefore, anatomical measurements were performed via optical microscopy in selected earlywood and latewood samples after each treatment, and the results were compared to untreated wood samples. In this study, two temperatures (190 °C and 210 °C) were considered for the thermal modification process. The results showed that the level of temperature of modification affected to microstructure of cell wall. The cell wall thickness decreased as treatment temperature increased, whereas the average lumen diameter increased slightly as temperature increased. Thermally modified radiata pine showed signs of damage (cracks, broken cells and deformations in the wood cell wall). The proportion of destroyed area increased as temperature increased, and significant differences were evident for the thermal treatment at 210 °C.

Abrasion Resistance of Thermally Treated Beech Wood

The study focused on the abrasion resistance of beech wood thermally treated at high temperatures. A standard test for determining abradability, according to ISO 4649, was used. We studied factors such as the anatomical direction, temperature of treatment, and duration of treatment, as well as their effects on abrasion resistance performance. Four temperature levels (20 °C, 160 °C, 180 °C, and 200 °C) and three durations of treatment (1 h, 3 h, and 5 h) were used. Results showed that the anatomical direction was not a significant factor, but there was a strong influence of temperature and duration of treatment, respectively, on abrasion resistance. Due to a strong correlation between moisture content and abrasion resistance, the equilibrium moisture content of thermally treated wood could be used for the prediction of abrasion resistance

EFFICIENCY OF ANDIROBA, COPAIBA AND JATROPHA OILS TO IMPROVE THE RESISTANCE OF Pinus elliottii WOOD TO WOOD-DECAY FUNGI

ABSTRACT Non-renewable chemical products are still the most used for wood protection, however, they have negative aspects. Several problems associated with the extensive use of these substances have been reported, such as intoxication of animals and plants, and environmental contamination. This has led to a search for alternative methods of control that cause less impact on the environment. In this context, the use of natural products extracted from different plants can be an alternative to this industrial activity. The objective of this work was to evaluate the efficiency of andiroba, copaiba and jatropha oils, either pure or enriched with iodine (I2), to improve the biological resistance of Pinus elliottii wood to wood-decay fungi causing brown, white and soft rot. The andiroba and copaiba oils came from the state of Pará and the jatropha oil came from Paraíba. Thus, we performed resistance tests to accelerated decay (brown and white rot fungi) and soft rot tests in the laboratory. We used pure natural oils and those enriched with sublimated iodine in assessing efficiency. In turn, we evaluated the effects of volatilization and leaching on the efficiency of solutions against decaying fungi. Pure andiroba and jatropha oils were the least efficient in controlling the Trametes versicolor fungus in the accelerated decay biological assay. Moreover, the wood treated with pure copaiba oil (normal situation) was classified as non-resistant for controlling Postia placenta fungus. In the soft rot test, we observed that there was a tendency to improve the wood resistance (normal situation) with an increase in the iodine concentration (I2).

Effect of the thermal modification and nano-ZnO impregnation on the deterioration of Caribbean pine wood

This study aimed to investigate the effect of thermal modification and nano-zinc oxide (nano-ZnO) particle impregnation on the deterioration of Caribbean pine wood under field conditions. Samples were thermally-modified at various temperature levels (control, 180 °C, 200°C, and 220 °C). Nano-ZnO impregnation was done with an aqueous solution at 1,5 % in an autoclave under two-steps of pressure and vacuum. Unmodified and thermally-modified, non-impregnated and nano-ZnO impregnated samples were exposed to deterioration for five months in field tests. A deterioration index was used to evaluate the health condition of the samples. The mass loss and occurrence of termite tunnels in percentage were also determined. The nano-ZnO impregnation improved the resistance of unmodified wood to field-deterioration. The thermal modification at 180oC, and 200oC increased the wood deterioration and nano-ZnO impregnation did not improve their resistance. Unmodified and 220 oC modified samples had a lower mass loss by xylophages than other thermal treatments regardless of the nanoparticle impregnation. The nano-ZnO impregnation decreases the occurrence of termite tunnels in unmodified, 200 oC and 220 oC-modified samples

Anti-fungal and anti-termite activity of extractives compounds from thermally modified ash woods

Thermal modification of wood is a promising alternative to chemical and biocidal modification processes, increasing the biological durability and dimensional stability of wood. However, the wood-decay resistance properties of heat-treated wood are still not well known. The main objective of this study was to determine the biological resistance of heat-treated ash wood, and assess the antifungal and anti-termite activity of extractive compounds from heat-treated ash woods, depending on the intensity of the modification process (2 hours at 170, 200, 215, 228 (°C) - steam pressure). Untreated and heat-treated wood samples were extracted with water or acetone. The extracts were then used to determine inhibition effectiveness against white-rot (Trametes versicolor) and brown-rot (Rhodonia placenta) fungi. Whatman papers impregnated with extractives were used to evaluate the inhibition of termite feeding. Lastly, the extractives were analyzed by Gas Chromatography - Mass Spectrometry (GC-MS) and compared for their level of anti-termite and antifungal activity. The results showed that the degree of antifungal activity of these extracts depended on the solvent used during the extraction process and varied depending on heat treatment intensity. The extracts were more effective against brown-rot than white-rot fungi. However, the anti-termite activity of heat-treated ash wood extracts was not really significant. A GC-MS analysis showed that the main share of the extractives in untreated wood was removed. In addition, new chemical elements were generated by the thermal degradation of wood polymers (lignin and hemicelluloses), including aliphatic acids, monosaccharides and other products resulting from their dehydration reaction. The most abundant element was syringaldehyde, from lignin derived compounds, which might explain the antifungal activities of thermally treated ash wood extracts.

Improving the adaptability of apricot to abiotic environmental factors

As a result of many years of breeding work on interspecific and intersortial hybridization in the Samara region, 9 apricot varieties were created and submitted for state testing, of which 4 varieties were entered into the state register of the Russian Federation. In the organic dormancy phase, apricot trees of these hybrids have high frost resistance of wood and flowering buds. Favorable microzones for apricot cultivation were determined, the productivity of varieties was studied, and the fruit quality was assessed. Of the 8 years of observing apricot, six years were fruitful. Two years of harvest was absent due to freezing of flower buds from the onset of frost after prolonged thaws. Samarskij (32.2 kg from a tree), Vnuchok (43.4 kg) and Elita No. 1 (24.9 kg) sorts have high productivity. Ripening dates, weight and taste of apricot fruits depend on the variety, air temperature and the amount of precipitation. Large fruits are possessed by new varieties Avdeevskij, Andryushka, Andryushka, Bojcovyj, Seyanec Voenkomovskij. The best tastes were of the varieties Andryushka, Bojcovyj, Seyanec Voenkomovskij, Trofej (tasting score 4.5 points).

Decay resistance of wood and treated wood to 12 strains of fungi

Decay resistance of wood and treated wood to 12 strains of fungi