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| 1. |
Tsapko Yu.
Establishing regularities in the propagation of phase transformation front during timber thermal modification [Електронний ресурс] / Yu. Tsapko, O. Horbachova, А. Tsapko, S. Mazurchuk, D. Zavialov, N. Buiskykh // Восточно-Европейский журнал передовых технологий. - 2021. - № 1(10). - С. 30-36. - Режим доступу: http://nbuv.gov.ua/UJRN/Vejpte_2021_1(10)__5
Designing environmentally friendly protective materials for flammable liquids makes it possible to influence the processes of heat resistance and the physical-chemical properties of a protective coating over a certain time until the emergency is eliminated. Therefore, there is a need to study the conditions that form a barrier for thermal conductivity and to define a mechanism for decelerating the transfer of heat to a flammable liquid by using a foaming agent. Given this, a mathematical model has been built for the process of changing the concentration of a foaming agent when used as a coating. Based on the experimental data, it was established that the foaming layer destruction process took place over 618 s until the achieved critical thickness of the foaming layer made the conductivity cease. According to the derived dependences, the concentration value was calculated at which the critical value of the foaming layer thickness is achieved, which leads to the ignition of a flammable liquid, and is about 25 %. It has been proven that the process of decelerating the temperature involves the decomposition of a foaming agent under the influence of the temperature, with heat absorption and foam release, the insulation of heat at the surface of the flammable liquid. Given this, it has become possible to define the conditions for protecting flammable liquids using foaming agents by forming a barrier to thermal conductivity. Experimental studies have confirmed that under the influence of water evaporation and foaming agent diffusion into a layer of the flammable liquid, the critical amount of the foaming agent reached a minimum in 606 s and only then the flammable liquid ignited. Thus, there is reason to argue about the possibility of using foaming agents to protect the leaks of flammable liquids, capable of forming a protective layer at the surface of the material. It also becomes possible to establish methods for assessing the insulating capacity of a foaming agent that could inhibit the rate of temperature penetration and the release of flammable liquids' vapors.The creation of environmentally friendly protective materials for building structures made of wood could make it possible to influence the processes of stability and the physical-chemical properties at the thermal modification of hornbeam wood over a certain time. That necessitates studying the conditions for investigating phase transformations when the timber is exposed to high temperature, as well as establishing the mechanism of hornbeam wood thermal modification. Given this, a mathematical model of the phase transformation process during the transfer of heat flux to a sample was built. Based on the derived dependences, it was established that when hornbeam wood is exposed to temperature treatment, it undergoes endothermic phase transformations characterized by the heat absorption and change in the color of hornbeam wood. In particular, at a temperature of 200 <^>oC, the temperature in the wood decreases by 5 % due to the chemical changes in the structure of cell wall components (lignin, cellulose, and hemicellulose). It was found that the process of thermal modification is accompanied by the decomposition of hemicellulose and the amorphous part of cellulose, a decrease in moisture absorption, as well as a decrease in the volume of substances that are a medium for the development of fungi. In addition, lignin and the resulting pseudo lignin undergo a process of polymerization and redistribution throughout the cell volume. At the same time, they give the cell walls higher density, hardness, increase hydrophobicity (water repellency), thereby reducing the ability to absorb moisture and swell. It was established that the most effective parameter of phase transformations is the temperature and aging duration. The results of moisture absorption have been given; it has been found that over 6 hours of modified timber exposure, its moisture absorption decreases by more than 10 times, which allows its application at facilities with high humidity.This paper reports the analysis of compositions for fire protection of wood that established that there are not enough data to explain and describe the process of fire protection and, accordingly, the fire-hazardous properties of wood, in order to protect people. The development and research of a set of properties of fire-resistant materials leads to the design of new types of such materials. The object of this study was a fire-protective two-component intumescent varnish for wood. The essence of the research is to determine the indicators of fire danger of wood, fire-protected by coatings, and the impact exerted on them by the formed heat-insulating layer of coke, making it possible to justify the effectiveness of the fire-retardant coating under the influence of temperature. The volume of fire-retardant and hydrophobic coating has been optimized, which ensures the lowest value of loss of mass by fire-protected wood during thermal action. Its lowest value was determined when using flame retardant in the volume of 589 g/m<^>2 and a hydrophobic agent in the volume of 54 g/m<^>2. When determining the combustibility of fire-resistant wood, it was established that the temperature of flue gases during tests was no more than 103 <^>oC, the length of damage to the sample did not exceed 143 mm. At the same time, the weight loss did not exceed 19 g, and the independent burning of wood did not exceed 23 s. In addition, the wood withstood the surface effect of a heat flow of 35 kW/m<^>2, while surface combustion did not occur, and the value of the coefficient of smoke formation was 432 m<^>2/kg during the smoldering of the fire-proof sample. Unlike wood protection with fire-retardant swelling paint, the fireproof wood with two-component varnish, does not change color and refers to low combustibility materials; it is hard to ignite, dose not spread the flame by surface, with moderate smoke-forming ability. The practical significance is the fact that a certificate of conformity was issued based on the reported results. Thus, there are grounds to assert the possibility of directed adjustment of wood fire protection processes by using coatings that can form a protective layer on the surface of the material.The issue related to using dry wood products for building structures is to ensure their stability and durability during operation while it is necessary to take into consideration changes in their properties and structure. Therefore, the object of this study was pine wood struck by drying out. It is proved that in the process of drying, wood porosity decreases, and, accordingly, the tensile strength, depending on the degree of damage by the fungus. Specifically, with the area of damage in the range of 30 - 50 %, the strength limit decreases by more than 1,3 times, and if the fungus affects the area within 80 - 100 %, the wood becomes softer, more ductile while the strength limit is reduced by 1,1 times. Based on the results of physicochemical studies, discrepancies in the IR spectra were identified, indicating structural changes in the constituent components of wood. There is a decrease or absence of intensities of absorption bands of some functional groups and the appearance or intensification of others. Wood samples, in determining the highest calorific value, show a difference in values, which is explained by structural changes in wood components caused by biological processes. Thermogravimetric analysis data indicate complete burnout of dry pine wood. However, for wood with tree stands not weakened by drying, the coke residue burns out at a higher temperature. Wood with blue pigmentation affected by microorganisms has significant differences in the heating area of 400 - 700 <^>oC. The nature of coke burnout allows us to make assumptions about the different qualitative and quantitative composition of the coke residue, which is formed due to structural changes. The practical significance is the fact that the results of determining the properties and structure of dry wood make it possible to establish the operating conditions for articles and building structures.
| | 2. |
Tsapko Y.
Establishing regularities of temperature conductivity reduction when protecting fabric against fire by intumescent coating [Електронний ресурс] / Y. Tsapko, А. Tsapko, N. Buiskykh, O. Horbachova, S. Mazurchuk, A. Matviichuk, Y. Sarapin // Eastern-European journal of enterprise technologies. - 2022. - № 2(10). - С. 74-80. - Режим доступу: http://nbuv.gov.ua/UJRN/Vejpte_2022_2(10)__10
This paper has analyzed materials for fire protection of textile products; it was found that there are not enough data to explain and describe the process of fire protection. Neglecting modern coatings leads to the ignition of fabric structures under the action of flame. Devising reliable methods for studying the conditions of fabric fire protection leads to the design of new types of fireproof materials. Therefore, there is a need to determine the conditions that form a barrier to high fabric temperature and to establish a mechanism for inhibiting heat transfer to the material. In this regard, the thermal conductivity process was simulated on the fabric surface using an intumescent coating, which makes it possible to estimate the coefficient of thermal conductivity at high temperatures. Based on the experimental data and theoretical dependences, the thermal conductivity coefficient of the fire-retardant layer of coked foam was calculated, which is 8,9 x 10<^>-6 m<^>2/s, due to the formation of a heat-insulating layer. The study results proved that the process of thermal insulation of textile material involves not only the decomposition of flame retardants with the formation of inert gases that interact with the flame on the sample surface but also the inhibition of heat transfer to the material treated with an intumescent coating that forms a thermally-insulating layer of coked foam on the fabric surface. The maximum possible penetration of temperature was estimated, namely generating a temperature on the sample's surface that significantly exceeds the ignition temperature of the fabric, and does not exceed 215 <^>oC on the unheated surface. Thus, there is reason to argue about the possibility of targeted adjustment of the processes of fabric fire protection by applying coatings capable of forming a protective layer on the surface of the material, which inhibits the rate of heat transfer.
| | 3. |
Tsapko Y.
Establishing regularities in the application of dry pine wood [Електронний ресурс] / Y. Tsapko, N. Buiskykh, R. Likhnyovskyi, O. Horbachova, А. Tsapko, S. Mazurchuk, A. Matviichuk, M. Sukhanevych // Eastern-European journal of enterprise technologies. - 2022. - № 4(10). - С. 51-59. - Режим доступу: http://nbuv.gov.ua/UJRN/Vejpte_2022_4(10)__8
Designing environmentally friendly protective materials for flammable liquids makes it possible to influence the processes of heat resistance and the physical-chemical properties of a protective coating over a certain time until the emergency is eliminated. Therefore, there is a need to study the conditions that form a barrier for thermal conductivity and to define a mechanism for decelerating the transfer of heat to a flammable liquid by using a foaming agent. Given this, a mathematical model has been built for the process of changing the concentration of a foaming agent when used as a coating. Based on the experimental data, it was established that the foaming layer destruction process took place over 618 s until the achieved critical thickness of the foaming layer made the conductivity cease. According to the derived dependences, the concentration value was calculated at which the critical value of the foaming layer thickness is achieved, which leads to the ignition of a flammable liquid, and is about 25 %. It has been proven that the process of decelerating the temperature involves the decomposition of a foaming agent under the influence of the temperature, with heat absorption and foam release, the insulation of heat at the surface of the flammable liquid. Given this, it has become possible to define the conditions for protecting flammable liquids using foaming agents by forming a barrier to thermal conductivity. Experimental studies have confirmed that under the influence of water evaporation and foaming agent diffusion into a layer of the flammable liquid, the critical amount of the foaming agent reached a minimum in 606 s and only then the flammable liquid ignited. Thus, there is reason to argue about the possibility of using foaming agents to protect the leaks of flammable liquids, capable of forming a protective layer at the surface of the material. It also becomes possible to establish methods for assessing the insulating capacity of a foaming agent that could inhibit the rate of temperature penetration and the release of flammable liquids' vapors.The creation of environmentally friendly protective materials for building structures made of wood could make it possible to influence the processes of stability and the physical-chemical properties at the thermal modification of hornbeam wood over a certain time. That necessitates studying the conditions for investigating phase transformations when the timber is exposed to high temperature, as well as establishing the mechanism of hornbeam wood thermal modification. Given this, a mathematical model of the phase transformation process during the transfer of heat flux to a sample was built. Based on the derived dependences, it was established that when hornbeam wood is exposed to temperature treatment, it undergoes endothermic phase transformations characterized by the heat absorption and change in the color of hornbeam wood. In particular, at a temperature of 200 <^>oC, the temperature in the wood decreases by 5 % due to the chemical changes in the structure of cell wall components (lignin, cellulose, and hemicellulose). It was found that the process of thermal modification is accompanied by the decomposition of hemicellulose and the amorphous part of cellulose, a decrease in moisture absorption, as well as a decrease in the volume of substances that are a medium for the development of fungi. In addition, lignin and the resulting pseudo lignin undergo a process of polymerization and redistribution throughout the cell volume. At the same time, they give the cell walls higher density, hardness, increase hydrophobicity (water repellency), thereby reducing the ability to absorb moisture and swell. It was established that the most effective parameter of phase transformations is the temperature and aging duration. The results of moisture absorption have been given; it has been found that over 6 hours of modified timber exposure, its moisture absorption decreases by more than 10 times, which allows its application at facilities with high humidity.This paper reports the analysis of compositions for fire protection of wood that established that there are not enough data to explain and describe the process of fire protection and, accordingly, the fire-hazardous properties of wood, in order to protect people. The development and research of a set of properties of fire-resistant materials leads to the design of new types of such materials. The object of this study was a fire-protective two-component intumescent varnish for wood. The essence of the research is to determine the indicators of fire danger of wood, fire-protected by coatings, and the impact exerted on them by the formed heat-insulating layer of coke, making it possible to justify the effectiveness of the fire-retardant coating under the influence of temperature. The volume of fire-retardant and hydrophobic coating has been optimized, which ensures the lowest value of loss of mass by fire-protected wood during thermal action. Its lowest value was determined when using flame retardant in the volume of 589 g/m<^>2 and a hydrophobic agent in the volume of 54 g/m<^>2. When determining the combustibility of fire-resistant wood, it was established that the temperature of flue gases during tests was no more than 103 <^>oC, the length of damage to the sample did not exceed 143 mm. At the same time, the weight loss did not exceed 19 g, and the independent burning of wood did not exceed 23 s. In addition, the wood withstood the surface effect of a heat flow of 35 kW/m<^>2, while surface combustion did not occur, and the value of the coefficient of smoke formation was 432 m<^>2/kg during the smoldering of the fire-proof sample. Unlike wood protection with fire-retardant swelling paint, the fireproof wood with two-component varnish, does not change color and refers to low combustibility materials; it is hard to ignite, dose not spread the flame by surface, with moderate smoke-forming ability. The practical significance is the fact that a certificate of conformity was issued based on the reported results. Thus, there are grounds to assert the possibility of directed adjustment of wood fire protection processes by using coatings that can form a protective layer on the surface of the material.The issue related to using dry wood products for building structures is to ensure their stability and durability during operation while it is necessary to take into consideration changes in their properties and structure. Therefore, the object of this study was pine wood struck by drying out. It is proved that in the process of drying, wood porosity decreases, and, accordingly, the tensile strength, depending on the degree of damage by the fungus. Specifically, with the area of damage in the range of 30 - 50 %, the strength limit decreases by more than 1,3 times, and if the fungus affects the area within 80 - 100 %, the wood becomes softer, more ductile while the strength limit is reduced by 1,1 times. Based on the results of physicochemical studies, discrepancies in the IR spectra were identified, indicating structural changes in the constituent components of wood. There is a decrease or absence of intensities of absorption bands of some functional groups and the appearance or intensification of others. Wood samples, in determining the highest calorific value, show a difference in values, which is explained by structural changes in wood components caused by biological processes. Thermogravimetric analysis data indicate complete burnout of dry pine wood. However, for wood with tree stands not weakened by drying, the coke residue burns out at a higher temperature. Wood with blue pigmentation affected by microorganisms has significant differences in the heating area of 400 - 700 <^>oC. The nature of coke burnout allows us to make assumptions about the different qualitative and quantitative composition of the coke residue, which is formed due to structural changes. The practical significance is the fact that the results of determining the properties and structure of dry wood make it possible to establish the operating conditions for articles and building structures.
| | 4. |
Tsapko Y.
Determining patterns in the formation of a polymer shell by powder paint on wood surface [Електронний ресурс] / Y. Tsapko, R. Likhnyovskyi, N. Buiskykh, O. Horbachova, S. Mazurchuk, O. Lastivka, А. Tsapko, K. Sokolenko, A. Matviichuk // Eastern-European journal of enterprise technologies. - 2023. - № 1(10). - С. 37–45. - Режим доступу: http://nbuv.gov.ua/UJRN/Vejpte_2023_1(10)__6
An issue related to using wood and wood products for building structures is to ensure their stability and durability during operation within wide limits. Therefore, the object of this study was a change in the properties of the polymer shell of powder paint on wood during thermal modification. It is proved that in the process of thermal modification of wood, its structure changes, and accordingly, during the polymerization of powder paint, degassing occurs, which affects the polymer shell. Namely, during the thermal polymerization of powder paint at a temperature of 180 <^>oC for untreated wood, shallow bubbles and craters are characteristic of the formed polymer shell. Instead, a smooth surface is marked for a sample of thermally modified wood. Thermogravimetric analysis data show thermogravimetric curves characterized by the loss of mass of the sample of the original wood with increasing temperature due to the processes of dehydration, destruction of hemicellulose and lignin. This is dehydration, accompanied by the destruction of the pyranose cycle, and carbonization to form a carbon residue and a complex mixture of volatile products. Due to this, bubbles and craters are formed in the polymer shell of the coating. Based on the obtained results of adhesion of the polymer shell on wood, which is treated with a mixture of epoxy polyester system with functional additives and a polymerization temperature of 180 <^>oC, the adhesion level is 2,1 MPa. Reducing the polymerization temperature of a mixture of the epoxy polyester system with functional additives to 130 <^>oC increases adhesion by 1,75 times, and the nature of the destruction passes through the polymer shell. For thermally modified wood, the level of adhesion is within 2,1 MPa, and the destruction takes place through the wood. This is due to the increased fragility of the surface after thermal modification of wood.
| | 5. |
Tsapko Y.
Establishment of patterns in the thermal modification of dry pine wood [Електронний ресурс] / Y. Tsapko, O. Horbachova, R. Likhnyovskyi, S. Mazurchuk, А. Tsapko, N. Buiskykh, A. Matviichuk, O. Slutska, O. Korolova, D. Khromenkov // Eastern-European journal of enterprise technologies. - 2023. - № 4(10). - С. 24–36. - Режим доступу: http://nbuv.gov.ua/UJRN/Vejpte_2023_4(10)__5
| | 6. |
Horbachova O.
Identifying patterns in the resistance of thermally modified ash wood to weathering [Електронний ресурс] / O. Horbachova, S. Mazurchuk, V. Lomaha, N. Buiskykh, A. Matviichuk, N. Marchenko // Eastern-European journal of enterprise technologies. - 2025. - № 1(12). - С. 6–15. - Режим доступу: http://nbuv.gov.ua/UJRN/Vejpte_2025_1(12)__3
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