Papers by Keyword: Wood

Abstract: Experimental studies of some physical properties of paulownia wood and identifies differences in comparison with other popular species are presented. In particular, the regularities of hydration and dehydration processes were investigated. Based on the results obtained, reliable data on the hygroscopic properties of paulownia were obtained for the first time. It was found that the hydration rapidity of paulownia (V_pl = 1.493) exceeds the similar rate of pine (V_pn = 1.1313) at a temperature of 20 °C. Changing the temperature of the liquid in which the wood is modified leads to an increase in the impregnation rapidity and, therefore, increases the productivity of the process. The dehydration rapidity of both species is almost the same (k = –0.002), which allows them to be dried simultaneously in the same chamber, optimizing production logistics. The dependence of liquid absorption on concentration was investigated. It has been found that a higher concentration outside causes a greater diffusion flux into the sample, while a higher concentration inside leads to a decrease in the sample weight. During the hydration stage, the weight of paulownia samples increased by 4 times, and pine samples – by 2.5 times. A two-stage kinetic model of wood hydration has been developed, which adequately describes the dynamics of the process. The resulting S-shaped curve clearly characterizes the features of the kinetics processes with saturation. Verification showed a high correlation – 85 % – for hydration and over 90 % for dehydration, which allows for accurate modeling and prediction of the technological processes of wood impregnation and drying.

Abstract: The results of experimental study of combustion peculiarities of typical materials (alcohol, paper, wood and textiles) in a small-sized unsealed chamber are presented. By the method of exponential filtering of measurements by traditional fire sensors of temperature, smoke density and carbon monoxide concentration of the gaseous medium in the ceiling area of the experimental chamber, the combustion peculiarities of these materials were revealed. It is established that the dynamics of temperature, smoke density and gas medium concentration in the ceiling area of the chamber during the ignition of alcohol, paper, wood and textiles has a complex and non-stationary character. This character of dynamics is caused by complex and invisible mechanisms of interaction at the molecular and macroscopic levels of combustion materials with the gas medium of the chamber. It was found that the beginning of combustion of materials is characterized by the signs of appearance of the trend of growth and increase of fluctuations of temperature, smoke density and carbon monoxide concentration of the gas medium. These signs are representative, which allows recommending them for current detection of material ignition in order to prevent fire in the premises.

Abstract: The effect of magnesium hydrophosphate on rheokinetic, chemical-colloidal and flame retardant properties of flame retardant aluminosilicate paints for wood has been investigated. It is shown that the introduction of magnesium hydrophosphate in the paint composition in the amount of 1-1.5% allows to stabilize the change of dynamic viscosity from 164500 to 120000 cP in the range of speeds from 0.35 to 1 RPM, as well as to provide wettability (s=0. 659-0.6603) and stability of spread ability (k=-43.48 and k=- 43.65) of the paint on pine substrate, which corresponds to the criterion requirements. According to the data of fire tests it was found that modification of aluminosilicate bases of paints with magnesium hydrophosphate in the amount of 1-1.5% puts them in the category of difficult combustible and difficult to ignite, the temperature of flue gases did not exceed the critical value (<260С), mass loss did not exceed 5.4-7.2%, which corresponds to the I group of flammability G1 according to the standard. According to the shear force data (SS=24.95 to 176.45 dynes/cm² and SS=23.18 to 172.4 dynes/cm²) the investigated formulations can be applied on wooden surfaces by air spraying with a screw paint feed.

Abstract: An experimental study of the physical and mechanical properties of untreated and acetylated wood was conducted. The effect of acetylation on wood density was investigated. It was established that the density of the samples generally decreases after acetylation. As the level of acetylation increases, the fiber saturation point decreases in both conifers and hardwoods. Acetylation of wood helps to reduce the sorption properties of wood. The amount of swelling was analyzed. For untreated wood (aspen and alder), the volume swelling index is at the level of 7.5 %. Acetylation contributes to the stability of the geometric dimensions of structures, as the volume swelling index for aspen decreased by 4 times, for alder – by 2 times. An increase in the amount of swelling along the fibers is observed in all samples. Regarding the nature of the destruction of the samples during compression, the aspen (both untreated and acetylated) only crumples without visible signs of destruction. In some samples of alder, partial exfoliation is visible. It was found that acetylation has an ambiguous effect on the mechanical properties of wood of both species.

Abstract: The wood has been focused for sustainable development goals (SDGs) of many interior products and buildings. The durability and weatherability of wood as constituent material should be investigated for the safety. In this study, the fatigue test of Japanese cedar as wood was conducted after and before outdoor exposure tests for constituent materials of interior products and buildings. The test term is one month (start time: 9/7/2020). The test place for outdoor exposure test is Hino Tokyo, Japan. As a fatigue test condition, the frequency was 10 Hz. The stress level was 70-90% of the tensile strength. As a result, the fatigue property of Japanese cedar was affected by photo degradation because constituent materials on the surface of Japanese cedar mainly received ultraviolet wave under outdoor exposure environment.

Abstract: The study involves the use of high density polyethylene (HDPE) as a filament for 3D printing. Considering the warpage and adhesion problem of HDPE on the build plate during 3D printing, this was addressed through the incorporation of wood flour compatibilized with styrene-ethylene-butylene-styrene grafted maleic anhydride (SEBS-gMAH). The composite wood-HDPE (cHDPE) was studied to observe warpage changes. Using different SEBS, heat bed parameters and identification of the suitable print heat beds for HDPE was conducted. Results from the mechanical testing show that the compressive strength and elastic force of virgin HDPE (vHDPE) increases with infill percentage, while the same properties for cHDPE increases up to 50% infill density/percentage then decreases as it approaches 100% infill percentage. Digital microscopy imaging shows that poor layer adhesion initiated the poor compressive performance of cHDPE. Warp studies reveal that wood flour significantly decreases warping of HDPE by 42.88% at 50% infill density. While different SEBS brands show similar effectiveness as heat beds in reducing warping of HDPE during printing.

Abstract: The article presents the results of studies of the positive effect of compounds of the type A(NO₃)₂, as modifiers of the aluminosilicate adhesive of the composition Na2O∙Al2O∙6SiO2∙20H2O, on increasing the strength of adhesive joints of wood of various species. The grade strength increases 1.39 times compared to the strength of the adhesive that does not contain these compounds. According to the degree of influence on the shear strength along the fibers, the additives can be ranked in the series Ba (NO₃)₂ > Ca (NO₃)₂ > Mg (NO₃)₂ > 95%Ca (NO₃)₂+5%NH₄NO₃. It is noted that for gluing samples from a pine substrate, it is advisable to add magnesium and barium nitrates to the aluminosilicate glue in an amount of 1% (by weight); beech wood - calcium and barium nitrates in the amount of 1 and 0.5% (by weight); oak wood - calcium nitrates in an amount of 1% (by mass), a mixture of nitrates in an amount of 0.5% (by mass) and barium nitrate in an amount of 0.5 and 1.5% (by mass). According to the influence on the strength of adhesive joints, the substrates can be ranked in the order beech > oak > pine. Further studies will present the results of the effect of alkaline earth metal nitrates on the deformation properties of adhesive joints and on rheokinetic and colloid-chemical properties.

Abstract: Consideration was given to the issues relating to safety conditions and security arrangements during the thermal decomposition of wood at the time of the fire in the premises of domestic buildings. The data of experimental investigations obtained for the thermal decomposition of wood were given with the measurement data of the concentration of toxic gases (СО, СО₂), oxygen (О₂), and temperature depending on time and fire spreading conditions in the premises. The studies were carried out by comparing the changes in the temperature of the solid flammable materials with time and the emission intensity of toxic gas (СО, СО₂) under the limited oxygen access at the time of the fire. The research data confirm those obtained for the gaseous atmosphere composition in the premises during the thermal decomposition of the solid flammable materials.

Abstract: There are many valuable wooden buildings in the world, because timber has been used all over the world as a building material for a long time. However, there is an issue that timber deteriorates due to various factors. Therefore, in order to preserve these valuable wooden buildings, it is necessary to appropriately repair or reinforce treatment. One of the treatments is the resin filling method. In this method, filling the resin in order to restore the strength into an internal cavity caused by deterioration. It has become clear that it is possible to recover the strength using this method, however, we are still conducting construction based on the rule of thumb. Therefore, authors examined the resin characteristics in order to inject the resin in stable manner and ensure strength recovery. Authors focused on deteriorated timber due to termites, because Japan has a very high amount of such type of timber. Authors reports the following four aspects of the characteristics of resin filling into timber. 1. The Area velocity is determined by the injection pressure, width of the gap, and viscosity of the resin. 2. The resin spreads concentrically in the gap of wood, but there is no regularity in the random gap like deteriorated timber due to termites. 3. Authors proposed a new coefficient for the application, of a theoretical formula to deteriorated timber due to termites. 4. Authors proposed a flowchart of resin filling method to perform stable construction.

Abstract: Nowadays, smart technology plays an important role in engineering applications to improve the quality of life. Thus, the development of natural materials and the use of nanotechnology, will give wood new properties to maximize its benefit. It is clear that there is a great challenge to prove the strength and durability of wood acquiring new features to reach innovative use that can influence the current path in many engineering applications. Therefore, this paper summarizes a review of the possibility of using nano- and smart-technologies to make the most of the natural and acquired potential for adding new features and physical properties of wood to improve its efficiency in architectural and mechanical applications. Moreover, experiments have shown that the use of certain types of wood in many applications such as the manufacture of 3D vehicle simulation models to study dynamic behaviors as well as in the manufacture of mechanical measurement systems to improve accuracy. In conclusion, new directions under development in this field are proposed to provide solutions to important issues in the future of measurement and quality control systems that need scientific treatment.--