Establishing patterns of mass transfer under the action of water on the hydrophobic coating of the fire-retardant element of a tent

An issue related to the use of foaming agents to extinguish fires involving flammable liquids is to ensure the efficiency of vapor insulation of flammable liquid and the foam stability during operation. Therefore, the object of research was a change in the insulating properties of the foaming agent film when interacting with a polar combustible substance. It has been proven that the presence of foaming agent on a flammable liquid leads to the formation of an insulating film on the surface resistant to the combustion temperature of the liquid, due to which re-ignition shifts towards longer time. A film of foaming agent was formed on the surface of the flammable liquid by leaking from the screen, which led to the insulation of the surface. The measured contact area of the foaming film with the electrode was more than 6.2·10-3 m2, which indicates the formation of a barrier for temperature, which collapses over time. According to experimental data on changes in electrical resistance, the critical contact area of the foaming film with the electrode was calculated, at which the film is destroyed. Based on the derived dependences, the change in the process of mass transfer of the foaming film to a flammable liquid was calculated, equal to about 800 s. The maximum possible mass transfer of the foaming agent into the flammable liquid and the reduction of insulation capacity were evaluated. The peculiarities of foam supply to the surface of alcohol through the screen are that the quenching time was about 156 s while the critical intensity of the supply of the working solution of the foaming agent was 0.054 dm3/(m2·s). And the time interval before re-ignition was about 470 s, which is enough to cool the fire site. Thus, there is reason to assert the possibility of targeted control over the processes of extinguishing polar flammable liquids with a foaming agent

“…where ψ is the spreading coefficient (distribution) of the foaming agent. For the foaming agent, the boundary condition according to equation (1) will take the form [17]:…”

Section: Modeling Of Mass Transfer Characteristics For a Foaming Agen...mentioning

confidence: 99%

Determining the patterns of extinguishing polar flammable liquids with a film-forming foaming agent

Tsapko,

Likhnyovskyi,

Tsapko

et al. 2023

“…Determination of the effectiveness of coating with wood samples was carried out according to the working procedure, the essence of which was to experimentally determine the quality of the polymer shell of wood coating [15]. To obtain the efficiency values of the polymer shell of powder coating on wood, the equipment of a scanning electron microscope was used (Fig.…”

Section: Procedures For Determining the Properties Of Samplesmentioning

confidence: 99%

Determining patterns in the formation of a polymer shell by powder paint on wood surface

Tsapko

Likhnyovskyi²,

Buiskykh

et al. 2023

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 °C 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 °C, the adhesion level is 2.1 MPa. Reducing the polymerization temperature of a mixture of the epoxy polyester system with functional additives to 130 °C 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

“…The differential diffusion equation describing the process of absorption of water by a material [14] is as follows:…”

Section: Modeling the Process Of Absorption Of Water By Wood Through ...mentioning

confidence: 99%

Establishing regularities of wood protection against water absorption using a polymer shell

Tsapko

Horbachova

Mazurchuk

et al. 2022

Self Cite

This paper has analyzed protective materials for timber building structures and established the need to devise reliable methods for studying the process of water absorption by the surface of the construction structure necessary for designing new types of fire-retardant materials. Therefore, it becomes necessary to determine the conditions for the formation of a barrier for water absorption and to elucidate a mechanism for inhibiting the transfer of moisture to the material. In this regard, a mathematical model of the intensity of water mass transfer when using a polymer shell made of organic material as a coating has been built, which makes it possible to assess the effectiveness of the polymer shell by the amount of water absorbed. Based on the experimental data and theoretical dependences, the intensity of absorption of water by wood was calculated; and it has been established that the protective coating reduces the amount of water absorbed by more than 20 times. The results of determining the weight gain by a sample during water exposure indicate an ambiguous impact of the nature of protection on water absorption. In particular, this implies the presence of data sufficient for the qualitative process of inhibition of moisture diffusion; and detecting, on its basis, the point in time when the drop in the coating's efficiency begins. Analysis of the results of experiments reveals that the maximum increase in mass in the case of water absorption by a non-treated sample of wood was 40 % while the increase in the mass of wood samples treated with mixtures of oil and paraffin was less than 28 %. At the same time, the best protection is shown by a mixture of oil with paraffin within 90÷95 %. Thus, there are grounds to assert the possibility of directed regulation of wood protection processes through the use of polymer coatings that can form a protective layer on the surface of the material, which inhibits the rate of absorption of water.