Comparing the Effect of Nanoclays on the Water-resistance of Intumescent Fire-retardant Coatings

This paper reports a study into the effect of nanoclays on the water-resistance of the intumescent system ammonium polyphosphate/melamine/pentaerythritol/titanium dioxide/polymer (ethylene vinyl acetate (EVA) or styrene acrylate (SA). It has been established that adding nanoclay to a coating based on ethylene vinyl acetate increases the fire resistance limit of a metal plate by 30 %, and to a coating based on styrene acrylate – by 50 %. At the same time, coatings that include the EVA polymer are characterized by greater fire-retardant efficiency and less water resistance than coatings containing the SA polymer. It has been shown that intumescent coatings, regardless of the nature of the polymer, under the conditions of 80 % humidity over 800 days their reduce fire-protective properties by an average of 10 %. The loss of coating fire resistance occurs due to the leaching of pentaerythritol, ammonium polyphosphate, and polymer degradation by hydrolysis. The admixtures of nanoclays with a high degree of exfoliation to the studied system create a barrier effect and maximize the chemical formulation of the intumescent coating. The fireproof properties of coatings with organically-modified montmorillonite admixtures are maintained or reduced to 5 % under the conditions of 80 % humidity over 800 days. It has been determined that the direct effect of water on the coating over a period of more than 2 days leads to a significant decrease in the swelling coefficient of intumescent coatings, regardless of the content of a nanoclay admixture in their composition. At the same time, the half-decay period of coatings without nanoclay, calculated on the basis of solubility constant in water, is 0.5 days. For coatings, which include the admixtures of organically-modified nanoclays, the half-decay period increases to 2 days. The results reported in this paper could be recommended for designing water-proof fire-resistant reactive-type nano-coatings with prolonged service life

Comparison of Fire Resistance of Polymers in Intumescent Coatings for Steel Structures

Thermal destruction of fire-retardant intumescent coating of the composition of ammonium polyphosphate (APP)/melamine (MA)/pentaerythrite (PE)/titanium oxide (TiO2)/polymer, which can be applied for fire protection of steel structures, was studied. The influence of polymers of different nature – ethylene-vinyl acetate (EVA), vinyl acetate versatate (VAVV), styrene acrylates, and vinyl toluene acrylate on the processes of formation of a coke layer and fire-retardant effectiveness of appropriate coatings was determined.Chemical transformations of polymers EVA and styrene acrylate in the intumescent system of ARR/MA/PE/TiO2 in the temperature range of 200–800 °С were studied. It was established that the processes of the thermal destruction of vinyl acetate polymer are more harmonized with chemical reactions of the components of the intumescent system than similar processes for acrylate aromatic polymers.Thermal-oxidation destruction of intumescent compositions at the temperatures of 200–800 °С was explored. It was shown that basic chemical processes with polymers of EVA and VAVV begin after 300 °С and flow in the temperature range of 350–600 °С. It was found that the noticeable degradation of the carbon-phosphorus frame of intumescent compositions with styrene acrylate polymers begins at 450 °С, which is almost by 150 °С below the temperature of degradation of the compositions containing vinyl acetate binders.The conducted fire tests demonstrate that intumescent compositions with the use of acrylate aromatic polymers are more effective at the low coating thickness in ensuring the fire resistance boundary of 30 min. In order to ensure higher values of fire resistance, it is necessary to use intumescent coatings containing vinyl acetate co-polymers as the polymer component.The study of the impact of polymers of intumescent coatings on the boundary of fire resistance of steel structures has scientific and practical significance for the development of differentiated fire protection means, oriented to the given class of fire resistance. Fire-retardant intumescent compositions examined in this study can be used as the basis for the formulations of materials for fire protection of building structures under conditions of a standard fir