ПОРІВНЯННЯ АМІНІВ ЯК ГАЗОУТВОРЮВАЧІВ ВОГНЕЗАХИСНИХ КОМПОЗИЦІЙ ІНТУМЕСЦЕНТНОГО ТИПУ

Purpose. Study of influence of blowing agents amines structure on the construction processes of thermal insulating char layer of intumescent system ammonium polyphosphate/pentaerythritol/amine and fire protection efficiency of this system at high temperatures. Methodology. A fire retardant mixture of ammonium polyphosphate/pentaerythritol/amine was chosen as a model intumescent system. Dispersion of vinyl acetate copolymer with vinyl ether of versatic acid was used as a polymeric component. A step-by-step study of the characteristics of the char layer of the intumescent composition was applied in the study, consisting in the analysis of the characteristics of the char formed after keeping the intumescent composition samples at a certain temperature between 100 and 800 °C, char residue mass (m, %), structure and density of the formed char layer. The method of infrared spectroscopy was used for identification of products of thermolysis of intumescent systems. Determination of fire protection efficiency of intumescent coatings was carried out in a mini-oven under standard fire conditions. Findings. The influence of the structure of amines blowing agents on the formation of char layer of intumescent system ammonium polyphosphate/pentaerythritol/amine was studied. Physico-chemical parameters of char layer formed during high temperature swelling of intumescent system components with varying amine: urea, melamine, dicyandiamide, guanidine, thiocarbamide, formylthiosemicarbazide, thiosemicarbazide, phenylethylcarbamide have been determined. In the temperature range 200–400 oC for systems with linear amines (urea, thiocarbamide, thiosemicarbazide), there is a rapid formation of insulating layer with intense outgassing (high intumescent coefficients K) and the same rapid its destruction with significant losses of char residue mass (Δm). The presence of melamine, dicyandiamide and guanidine in intumescent system provides constancy of intumescent coefficient at minimal mass loss. Chemical transformations of intumescent systems were studied by the method of infrared spectroscopy when the investigated amines were varied. It was found that linear diamines do not form stable spatially branched phosphamide compounds with phosphates as the basis of a thermostable heat-insulating frame. At the same time in IR spectra of char residue systems with melamine, dicyandiamide and guanidine the absorption bands of P-N-C bonds (1070–1050 cm-1) and P-N (980–950 cm-1) up to 600–700 oC are observed. Fire tests proved that melamine, dicyandiamide and guanidine are blowing agents providing maximum protection of metal against fire and can be used for composition of fire retardants for steel constructions.Originality. It has been proved that amines in intumescent polyphosphate system perform at least two functions: blowing agents by means of thermal destruction to incombustible gases and nucleophilic compound that takes part in char layer formation by aminolysis of electrophilic substrates.Practical value. The optimum amine blowing agents for developing formulations of intumescent coatings with enhanced flame retardant properties have been established.

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ПОРІВНЯННЯ ПОЛІОЛІВ ЯК КАРБОНІЗУЮЧИХ АГЕНТІВ ВОГНЕЗАХИСНИХ КОМПОЗИЦІЙ ІНТУМЕСЦЕНТНОГО ТИПУ

Technologies and Engineering ◽

10.30857/2786-5371.2021.6.3 ◽

2022 ◽

pp. 27-36

Author(s):

LIUBOV VAKHITOVA ◽

KONSTANTIN KALAFAT ◽

NADIYA TARAN ◽

VOLODYMYR BESSARABOV

Keyword(s):

High Temperatures ◽

Fire Protection ◽

Flame Retardants ◽

Fire Retardant ◽

Reaction Products ◽

Protection Efficiency ◽

Char Layer ◽

Thermal Insulating ◽

Intumescent Coatings ◽

Intumescent System

Purpose. To study the influence of the carbonizing agent structure on the formation of thermal insulating char layer of intumescent system acid donor/polyol and on the fire protection efficiency of the system at high temperatures. Methodology. A fire retardant mixture of an acid donor (phosphates ammonium, urea, melamine)/ polyol was chosen as a model intumescent system. Dispersion of vinyl acetate copolymer with ethylene was used as a polymeric component. The study applied the characteristics of the char layer of the intumescent composition at a certain temperature. The volumetric intumescent coefficient (K, cm3/g), mass of char residue (m, %), structure and density of the char layer are proposed as the main estimated parameters of flame retardant effect. IR spectroscopy was used to identify products of thermolysis of intumescent systems. Determination of fire protection efficiency of intumescent coatings was carried out in a mini-oven under standard fire conditions. Findings. The influence of polyol structure on the formation of thermal insulating char layer of intumescent acid donor/polyol system and the prediction of fire protection efficiency of this system under high temperature conditions has been investigated. It has been shown that under conditions of thermal shock the fire protection efficiency is more dependent on the nucleophilic reactivity of the polyol towards the unsaturated phosphorus atom of the acid donor than on its thermal stability. It has been found that pentaerythritol, dipentaerythritol, starch, dextrin, xylitol and sorbitol are the most effective carbonizing agents, regardless of the structure of the acid donor. It has been proved by infrared spectroscopy that at high temperatures as a result of the decomposition of pentaerythritol one of the reaction products is the aldehydes interacting with pentaerythritol with the formation of oligomeric compounds with a simple ether bond C-O-C. At the same time, pentaerythritol can be considered as a universal source of carbon framework for intumescent flame retardants regardless of the phosphate structure used. Originality. It has been shown that an important factor to increase the fire protection efficiency of intumescent systems is the use of polyols with an increased nucleophilicity in the esterification between polyol and phosphoric acid.Practical value. The optimal polyols as carbonizing agents for formulation of intumescent coatings with enhanced fire protection properties have been determined.

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ПІДВИЩЕННЯ ВОГНЕЗАХИСНОЇ ЕФЕКТИВНОСТІ ІНТУМЕСЦЕНТНИХ ЕПОКСИДНИХ ПОКРИТТІВ СПОЛУКАМИ ІНТЕРКАЛЬОВАНОГО ГРАФІТУ

Bulletin of the Kyiv National University of Technologies and Design Technical Science Series ◽

10.30857/1813-6796.2020.6.5 ◽

2021 ◽

Vol 152 (6) ◽

pp. 55-65

Author(s):

Л. М. Вахітова ◽

В. П. Плаван ◽

В. І. Шологон ◽

К. В. Калафат ◽

Н. А. Таран ◽

...

Keyword(s):

Epoxy Resin ◽

Oxidative Degradation ◽

Fire Retardant ◽

Ammonium Polyphosphate ◽

Thermal Oxidative Degradation ◽

Char Residue ◽

Temperature Range ◽

Char Layer ◽

Polymer Component ◽

Intumescent System

Investigation of the effect of nitrate oxide graphite on the parameters of char layer, obtained from the system of ammonium polyphosphate / melamine / pentaerythritol / epoxy resin under the influence of temperatures of 200–800 °С. Methodology. A fire retardant mixture was chosen as a model intumescent system ammonium polyphosphate / melamine / pentaerythritol. As a polymer component was used bisphenols A / F epoxy resin together with a polyamidoamine hardener. Nitrate oxide graphite was obtained by oxidation of natural scaly graphite with fuming nitrogen acid. The effect of impurities of nitrate oxide graphite was determined by thermogravimetry on the intumescence coefficient of intumescent compositions and the mass of the char residue intumescent compositions in temperature range of 200–800 °С. Findings. The influence of nitrate oxide graphite on the characteristics was studied of char layer of epoxy intumescent system ammonium polyphosphate / melamine / pentaerythritol / epoxy resin. The study of thermal oxidative degradation was carried out intumescent compositions in the temperature range 200–800 °С. It was shown that intercalated graphite compounds increase the thermal stability of the formed char layer at temperatures > 600 °С. Determined intumescence coefficients and thermogravimetric analysis of modified intumescent systems was performed nitrate oxide graphite with different degrees of intercalation, in the conditions of 200–800 °С. It was established that the optimal parameters of the char layer are in terms of volume intumescence coefficient and mass of the char residue are provided by graphites, which contain 15–25% of intercalant in its composition. But the results obtained allow us to determine nitrate oxide graphite as a promising modifier of epoxy intumescent systems to increase its fire protection efficiency. Originality. The influence of degree of intercalation of nitrate oxide graphite was studied on the characteristics of char layer of epoxy intumescent system for the first time. Practical value. The optimal content of intercalant in nitrate oxide graphite was established for the development of formulations of intumescent epoxy coatings with increased fire retardant properties.

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In situ thermal-conductivity measurements and morphological characterization of intumescent coatings for fire protection

Journal of Fire Sciences ◽

10.1177/0734904118794955 ◽

2018 ◽

Vol 36 (5) ◽

pp. 419-437 ◽

Cited By ~ 3

Author(s):

Jiyuan Kang ◽

Fumiaki Takahashi ◽

James S T’ien

Keyword(s):

Thermal Conductivity ◽

Heat Flux ◽

Fire Protection ◽

Heat Fluxes ◽

Loss Cone ◽

Char Layer ◽

Intumescent Coatings ◽

Apparent Thermal Conductivity ◽

Initial Coating

Thermal insulating performance and char-layer properties have been studied for water-based intumescent coatings for structural steel fire protection using a new laboratory-scale mass-loss cone apparatus. A specimen (100 × 100 mm mild steel plate; the initial coating thickness: 0.3–2.0 mm) is placed horizontally and exposed to a constant incident radiant heat flux (25, 50, or 75 kW/m2). The apparent thermal conductivity of the expanding char layer is determined in situ based on real-time measurements of the temperature distribution in the char layer and the heat flux transmitted through the char layer. Three-dimensional morphological observations of the expanded char layer are made using a computed tomographic–based analytical method. The vertical variation of the porosity of the expanded char layer is measured. The measured heat-blocking efficiency is correlated strongly with the incident heat flux, which increases the expanded char-layer thickness, and porosity for sufficiently large initial coating thicknesses (>0.76 mm). For a thin coating (0.30 mm), violent off-gassing disrupts the intumescing processes to form a consistent char layer after abrupt exposure to higher incident heat fluxes, thus resulting in lower heat-blocking efficiency. Therefore, the product application thickness must exceed a proper threshold value to ensure an adequate thermal insulation performance.

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Intumescent Type Fire Retardant Epoxy Coating

Materials Science Forum ◽

10.4028/www.scientific.net/msf.992.605 ◽

2020 ◽

Vol 992 ◽

pp. 605-609

Author(s):

L. Pestereva ◽

N. Shakirov ◽

Оlga G. Shakirova

Keyword(s):

Fire Resistance ◽

Fire Protection ◽

High Performance ◽

Fire Retardant ◽

Epoxy Coating ◽

Performance Characteristics ◽

Ammonium Polyphosphate ◽

Metal Structures ◽

Intumescent Coatings ◽

Fire Retardant Properties

This article discusses one of the methods of fire protection, namely, the coating of metal structures with fire retardant paints. Intumescent coatings are currently the most widely used. Fire retardant coatings based on epoxy paints have high performance characteristics and are promising. As the foaming component, the system of ammonium polyphosphate - pentaerythritol - melamine (in a ratio of 2: 1: 1) was selected. The fire retardant properties of the developed material were investigated. Coatings on the base of the developed fire retardant paint allow us to increase own level of fire resistance of metal constructions up to three (90 minutes).

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The effect of ammonium polyphosphate:melamine:pentaerythritol ratio on the efficiency of fire protection of reactive coatings

Voprosy Khimii i Khimicheskoi Tekhnologii ◽

10.32434/0321-4095-2020-133-6-59-68 ◽

2020 ◽

pp. 59-68

Keyword(s):

Fire Resistance ◽

Fire Protection ◽

Protective Coatings ◽

Effective Means ◽

Ammonium Polyphosphate ◽

Protective Efficiency ◽

Steel Construction ◽

Additive Increase ◽

Main Components ◽

Intumescent System

In order to optimize the formulation of fire protective coatings for metal constructions, the effect of the ratio of main components in an intumescent system "ammonium polyphosphate–melamine–pentaerythritol" on the thermal destruction of the coating under conditions of fire (200–8000C) has been investigated. Thermal transformations of coatings were studied both by thermogravimetry with stepwise determination of the expansion coefficient by temperature variation and by IR spectroscopy. It was established for the first time that the ratio of ammonium polyphosphate, melamine and pentaerythritol as well as their content in the intumescent system is a factor determining the limit of the fire resistance of steel constructions, which a fire protective coating can ensure. Intumescent coatings with an ammonium polyphosphate:melamine:pentaerythritol ratio of 2:1:1 were shown to be more effective ones to provide the fire resistance of a steel construction during 30 minutes (R30). In turn, the use of the above ratio of 3.5:1:1.5 can provide the limit of the fire resistance of steel construction during 60 minutes (R60). The mixture of melamine and dicyandiamide in the intumescent system causes a synergistic effect, which leads to a non-additive increase in the fire protective efficiency of the coating. The results of this study have been confirmed by full-scale fire tests; they may be used to develop effective means of fire protection of steel constructions.

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Fire Protection Performance and Thermal Behavior of Thin Film Intumescent Coating

Coatings ◽

10.3390/coatings9080483 ◽

2019 ◽

Vol 9 (8) ◽

pp. 483 ◽

Cited By ~ 7

Author(s):

Jing Han Beh ◽

Ming Chian Yew ◽

Ming Kun Yew ◽

Lip Huat Saw

Keyword(s):

Thin Film ◽

Thermal Behavior ◽

Heat Release ◽

Fire Protection ◽

Filler Content ◽

Equilibrium Temperature ◽

Fire Propagation ◽

Char Layer ◽

Intumescent Coatings ◽

Heat Released

This paper presents the heat release characteristics, char formation and fire protection performance of thin-film intumescent coatings that integrate eggshell (ES) as an innovative and renewable flame-retardant bio-filler. A cone calorimeter was used to determine the thermal behavior of the samples in the condensed phase in line with the ISO 5660-1 standard. The fire resistance of the coatings was evaluated using a Bunsen burner test to examine the equilibrium temperature and formation of the char layer. The fire propagation test was also conducted according to BS 476: Part 6. On exposure, the samples X, Y, and Z were qualified to be Class 0 materials due to the indexes of fire propagation being below 12. Samples Y and Z reinforced with 3.50 wt.% and 2.50 wt.% of ES bio-filler, respectively, showed a significant improvement in reducing the heat release rate, providing a more uniform and thicker char layer. As a result, the addition of bio-filler content has proven to be efficient in stopping the fire propagation as well as reducing the total heat released and equilibrium temperature of the intumescent coatings.

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SEBS-based thermoplastic elastomers containing aluminum hypophosphite and melamine cyanurate: Thermal degradation, flame retardancy, and mechanical properties

Journal of Fire Sciences ◽

10.1177/0734904119830591 ◽

2019 ◽

Vol 37 (2) ◽

pp. 137-154 ◽

Cited By ~ 1

Author(s):

Xi Cheng ◽

Jianming Wu ◽

Yulin Li ◽

Chenguang Yao ◽

Guisheng Yang

Keyword(s):

Flame Retardant ◽

Thermoplastic Elastomers ◽

Char Residue ◽

Melamine Cyanurate ◽

Char Layer ◽

Phenylene Oxide ◽

Peak Heat Release Rate ◽

Ul 94 ◽

Flame Retardant Properties ◽

Aluminum Hypophosphite

Aluminum hypophosphite combined with melamine cyanurate and poly(phenylene oxide) was applied to flame-retard TPE-S system (blends of SEBS and polyolefin). The flame-retardant properties of the TPE-S/AHP/MCA/PPO were investigated by LOI and vertical burning test (UL-94). The results indicated that TPE-S containing 16 wt% AHP, 20 wt% MCA, and 10 wt% PPO reached a V-0 rating in the UL-94 test, and its LOI value was 28.2%. It performed well in the cone calorimeter (reduction in peak heat release rate from 2001 to 494 kW m−2). Thermogravimetric-Fourier transform infrared spectroscopy tests showed that AHP and MCA acted in gaseous phase, while AHP and PPO helped to form char residue. The SEM graphs demonstrated that continuous and compact films cover bubbles of the char layer in TPE-S/AHP/MCA/PPO. The proposed flame-retardant mechanisms of such systems were summarized.

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