OBTAINING OLIGOMER FIRE ANTIFANTS FOR POLYVINYL CHLORIDE COMPOSITIONS AND THEIR RESEARCH RESULTS

АННОТАЦИЯ

В статье описано получение олигомерных антипиренов для поливинилхлоридных композиций. Функциональные группы синтезированного вещества анализировали методом ИК-спектрального анализа полученных антиперинов, состав и строение полученного вещества - методом элементного анализа, индекс горения - по кислородному индексу, а также линии эндо- и экзотермического поглощения - методом результаты термического анализа.

ABSTRACT

The article describes the production of oligomeric fire retardants for polyvinyl chloride compositions. The functional groups of the synthesized substance were analyzed by the method of IR spectral analysis of the obtained antipyrenes, the composition and structure of the obtained substance - by the method of elemental analysis, the combustion index - by the oxygen index, as well as the lines of endo- and exothermic absorption - by the method of results of thermal analysis.

Ключевые слова. Поливинилхлорид, пластификаторы, наполнители, меламин, оксид алюминия, кислородный индекс, термический анализ.

Keywords. Polyvinyl chloride, plasticizers, fillers, melamine, aluminum oxide, oxygen index, thermal analysis.

Introduction. 60% of the fires occurring in the world in recent years are caused by short circuits in electric cables, and as a result of accidents, buildings and structures become unusable. Polyvinyl chloride polymers, which form the basis of electric cables, are treated with flame retardants in order to increase their fire resistance. Such processing of cable materials based on polyvinyl chloride will increase by 5.7% in 2022.

Polyvinyl chloride is used in compositions that are part of the polymer and in various mixtures that make the polymer practical for processing. In the production of polyvinyl chloride, it is obtained by suspension or emulsion polymerization of vinyl chloride monomer [1].

Polyvinyl chloride compositions are intermediates for the production of various types of products. Depending on the composition, they are divided into soft and hard. PVC compositions always contain heat stabilizers and lubricants, as well as impact modifiers designed to absorb the impact energy of plastic deformation. They are most commonly used in the production of hoses, furniture and tiles [2].

The purpose of the article. Polyvinyl chloride cable sheathing consists of fire protection coatings with polyfunctional flame retardants obtained on the basis of local raw materials.

Also, according to GOST 12.1.044-89, the method of experimental determination of the group of hard-burning and combustible solid fashion and materials, smoke generation coefficient of materials according to GOST 12.1.044-89, oxygen according to GOST 12.1.044-89, ISO 4589 (ASTMD2863) index (flammability index) and thermomechanical analysis methods were obtained for coatings for polyvinyl chloride and their physical and chemical properties were determined.

Methods of obtaining and research. Oligomer fire retardants were obtained for polyvinyl chloride contents and the oxygen index was determined according to the ISO 4589 (ASTMD2863) GOST 12.1.044-89 standard for the purpose of determining its flammability index.

Flammability is determined by the oxygen index (KI) method in rod-shaped samples with a length of 80-120 mm, a width of (10 ± 0.5) mm and a thickness of 3-4 mm according to GOST 12.1.044-89. The sample is placed vertically in the middle of the column, so that the upper edge of the sample is at least 100 mm from the upper open edge of the column.

According to GOST 12.1.044-89, the experimental method for determining the oxygen index is to find the minimum concentration of oxygen in the flow of an oxygen-nitrogen mixture, in which spontaneous combustion of a vertically located sample is observed.

Figure 1. Snov experimental procedure according to GOST 12.1.044-89

Highly effective flame retardants containing metal were obtained, and the effect of these flame retardants on PVC polymer materials and the mechanisms of increasing their fire resistance were studied.

Experimental part. In order to study the existing composition of the synthesized PVC-MP-Mg brand flame retardant, the indicators of the IR spectrum were analyzed (Fig. 2).

Figure 2. IR spectrum of PVC-MP-Mg composite

The main bonds characterizing IR spectroscopy of PVC-MP-Mg fire retardant based on melamine-polyphosphate ammonium magnesium compound are the following. In the IR spectroscopy of melamine - polyphosphate ammonium, it is possible to analyze the bonds formed mainly by phosphorus and nitrogen groups. It is possible to analyze the presence of R=O bonds at 1100 - 1330 cm^-1 and the presence of R-O- bonds at 999.13 - 1047 cm^-1. At the same time, the presence of R-O-R bonds at 860-964 cm^-1 in the flame retardant was determined through analysis.

In order to find out what elements are present on the surface of PVC modified with PVC-M brand oligomeric flame retardants, an elemental analysis was carried out. When studying the elemental analysis, it is possible to see silicon, phosphorus, sulfur and metals in the carbon, oxygen and flame retardants belonging to the polymer.

Figure 3. Elemental analysis of PVC modified with PVC-M oligomeric flame retardants

Thus, using fire retardants obtained on the basis of local raw materials, modified polymer materials reveal properties to increase fire resistance and reduce environmental impact. The widespread use of polymer materials based on fire-resistant PVC in the field of energy and construction, as well as in various production enterprises, leads to environmental and economic efficiency.

Results and their discussion. Modification with synthesized PVC-M, PVC-MP-Al, PVC-MP-Mg, PVC-MP-Zn, PVC-B and PVC-A oligomeric flame retardants and their thermal stability were studied (Fig. 4).

Figure 4. Thermal stability analysis of oligomeric flame retardants

The first mass loss of the PVC sample under the influence of temperature corresponds to the temperature range of 140-147 ^oС, and the mass loss is 8-10%. The second mass loss resulted in a mass loss of up to 50% due to the effect of heat on the PVC sample with the occurrence of endothermic and exothermic processes in the temperature range of 150-270 ^oC. The third stage of thermal decomposition of plasticized PVC involved temperatures of 285-600 ^oC and resulted in complete decomposition of the PVC sample.

Table 1.

Results of thermal gravimetric analysis of PVC samples.

The property of thermal decomposition of polymers is considered very important, and the fire resistance properties of materials, i.e., heat release and mass loss under the influence of temperature, play a major role in solving problems related to its ignition.

Conclusion. As a result of the researches of the obtained IR spectrum, it was determined that there are S-N/NH₂ and C=N bonds. In addition, it has been determined that absorption in areas with the placement of metal groups in flame retardants. Thus, fire retardants based on melamine-polyphosphate ammonium oligomers were obtained. When comparing the IR spectroscopy analysis of the studied sample with analogs, it was found that the characteristic bonds are close to each other. As a result of the study of differential-thermogravimetric analysis, these processes are the working mechanisms of compounds containing phosphorus, nitrogen, silicon and metal in flame retardants, which delay the ignition of PVC as a result of their change under the influence of heat.

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