Defect and Diffusion Forum Vol. 438

Abstract: One of the promising directions for ensuring the fire resistance of wooden building materials is the development of silicon phosphate compositions, thanks to which the formation of a protective layer is possible, which effectively prevents the spread of fire. The paper examines the possibility of using orthophosphate acid as a modifying additive for silicic acid sols. The influence of H₃PO₄ concentration on the rheological characteristics of the studied sols was determined. Sols with small amounts of orthophosphate acid (1–2%) lost their fluidity in the interval of 45–70 minutes. Increase of the additive content to 8% led to a sharp increase in optical density values and extended the survivability interval of the sol to 24 hours. Coatings based on gels with 1–2% orthophosphate acid were elastic, but increasing the content of the additive led to the formation of hard, inelastic coatings.According to the results of infrared (IR) spectroscopy, the effect of orthophosphate acid on the nature of polycondensation was confirmed. The degree of polycondensation was estimated by the ratio of intensity (I) and band width (d) at 1050 cm^–1, which corresponds to the vibrations of Si-O-Si bonds. Based on the comparison of I/d indicator values, the formation of linear siloxane chains was confirmed in the case of the use of small H₃PO₄ additions. Linear polycondensation ensures greater homogeneity of the gel, which was confirmed by IR spectroscopy of gels heat-treated at 800 °C and by microscopic observations. The coating on the wood surface, based on a fire-resistant silica-containing composition with small additions of orthophosphate acid, had the most uniform and continuous structure.

Abstract: The oscillations presence of the substance condensed state parameters and the n-alkanes combustion process was analyzed. It is shown that the smallest substance structural unit that describes such features is a dimer, a hexamer for methane, and a trimer for ethane. The cluster "equivalent length" based on the framework number atoms in the continuous chain and without taking into account cluster side parts was used as a modulating parameter. Attention was drawn to the dependences similarity for water solubility and the autoignition temperature of n-alkanes. It is proposed to take into account clustering involving water molecules for the water solubility, and oxygen molecules in the peroxide groups form that form similar clusters for combustion processes. It is accepted that the solubility limit is determined by the condition of all water molecules aggregation by the substance, and in combustible mixtures the substance aggregates all available oxygen in the air. Corresponding peroxide proportions allow the burning limits, detonation limits, stoichiometric concentration and cold flame limit to be described. An approximation formula has been developed that describes the general dependence of the n-alkanes and 2-methylalkanes autoignition temperature based on values of the cluster length and the monomer molecular weight.

Abstract: У даному дослідженні представлені можливості використання вогнегасної речовини на основі водорозчинного полімеру для ліквідації пожеж на полігонах ТПВ та полігонах побутових відходів, пожежне навантаження яких утворюється за рахунок твердих горючих матеріалів. Теоретично та експериментально показано, що шляхом зміни концентрації гелеутворювальних добавок можна змінювати в'язкість, що безпосередньо впливає на швидкість випаровування та глибину проникнення вогнегасної речовини в осередок пожежі. Наведено результати експериментальних досліджень ефективності гелевих вогнегасників на основі полімеру ECOFLOC A-07.

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.