Papers by Keyword: Wood

Abstract: Sawdust and used plastic materials are generally considered as waste and due to the inability of the later to degrade, it constitutes a lot of hazard to the environment and ecosystem. This research aimed at evaluating the performance and quality of the extrudates produced from a single screw wood-plastic composite extruder. The machine performance was evaluated using shredded Poly ethylene, terephthalate (PET) and high-density polyethylene (HDPE) to produce wood-plastic composites. The composite comprising of six samples of different mix ratios (plastic to stone dust mix ratio of 60:40, 70:30 and 80:20 and plastic to sawdust mix ratio of 60:40, 70:30 and 80:20) of the materials. Temperature range of 200°C to 300°C was adopted throughout the evaluation. The plastic composite was shredded into smaller bits and then inserted into the plastic chamber for melting at a determined temperature. The functional efficiency, throughput capacity, specific energy consumption, and selected physical properties were evaluated. Data collected were analyzed using Microsoft Excel package. It was discovered that the extruder work optimally when the mixing ratio of plastic to sawdust and plastic to stone dust content were in the ratio 80% and 20% which gave the functional efficiency of 73% and 84% respectively. However, it was observed that the throughput capacity of the machine has the highest at the 70% and 30% mixing ratio of plastic to stone dust of 7.2 kg/hr and plastic to sawdust of 9.38 kg/hr respectively. Also, the specific energy consumption has its highest value at 60% and 40% mixing ratio of the plastic to stone dust and saw dust of 5.67 KWh/Kg and 1.7 KWh/Kg respectively. A linear trend on the effect of the percentage of wood and stone content on the unit density of the products was also observed. It was observed that the higher the wood or stone dust content in the composite the denser the products. There are no changes in the physical composition in terms of size (length and thickness ) and mass such as water absorption, thickness swelling and linear expansion. It was observed that the extruder performed optimally when the percentage of plastic & wood and plastic & stone dust were in the mix ratio of 80 and 20 respectively. These products can be use for internal and external applications in buildings and other structures.

Abstract: A rheological model based on the new formulation of fractional calculus with variable order is developed to study the viscoelastic behavior of wood. The model, which uses only two rheological elements, exhibits an enhanced memory effect compared to constant-order fractional derivative models, demonstrated by a satisfactory fit to the experimental deformations observed in four-point bending tests on \textit{Pericopsis elata} samples. By determining the parameters of the linear function of the fractional order used, a physical significance emerges that explains the changes occurring within the material during the tests. This type of model, therefore, provides wood engineers with additional information about the behavior of the material under stress.

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.