Effects of expandable graphite on char morphology and pyrolysis of epoxy based intumescent fire-retardant coating

The current study was designed to investigate the effects of expandable graphite (EG) on fire protection properties of intumescent fire-retardant coating for steel structures. Several formulations of intumescent coating were prepared and tested according to ISO 834 for char expansion. The chars were found without cracks and bonded with the steel substrate. The results showed that the coating slowly degraded during the test and char remained in contact with vertically tested coated substrate. The coated substrates were also tested for weather resistance using humid and ultraviolet environment. The char was characterized by using FESEM, XRD, FTIR, TGA, and XPS analysis. FESEM examined char morphology of the coatings after furnace fire test. XRD and FTIR showed the presence of graphite, borophosphate; boron oxide and sassolite in the char. TGA and DTGA results disclosed that EG improved the residual mass of coating. XPS analysis showed the percentages of carbon and oxygen are 48.50 and 43.45 in char of formulation with 12.8% EG. The results of weathering test coatings showed decreased in char expansion because of a humidity and UV light. The formulation with 9.8% EG showed the maximum char expansion and high residual mass among the formulations investigated in this study. The weathering tested coated samples showed their capability of fire protection.     

Influences of glass flakes on fire protection and water resistance of waterborne intumescent fire resistive coating for steel structure

Glass flake (GF) was used as a modifier to improve the fire protection and water resistance of waterborne intumescent fire resistive coating. The influences of GF on the properties of the coatings were investigated in detail by using TGA, XRD, X-ray fluorescence spectrometry (XRF), SEM and fire protection test. The TGA results proved that addition of GF could enhance the anti-oxidation of the char layers and increase the residue weights of the coatings. The XRF results indicated that anti-oxidation of the coatings modified by GF was improved. The SEM images demonstrated that addition of GF could improve the foam structure of the coatings. After immersed in water over 600 h, the results showed that the thermal stability and fire protection of the coating without GF were significant decreased, but the coatings modified by GF could still maintain the excellent intumescent effect and fire protection.     

Effect of expandable graphite and ammonium polyphosphate on the thermal degradation and weathering of intumescent fire-retardant coating

This research aims to study the effect of ammonium polyphosphate and expandable graphite on the intumescent coating formulations (ICF). The coating presented in this research article is based on carbon source expandable graphite (EG), blowing agent melamine, acid source ammonium polyphosphate (APP), epoxy resin as a binder with polyamide amine. The stability of the developed coating was verified at 950°C for 1-hour fire test. The results showed that the coating is stable and well bond with the steel substrate. The char was characterized by using FESEM, XRD, FTIR, DTA, TGA, XPS, Py-GCMS and Weathering Test. The morphology of the char was studied by SEM of the coating after furnace fire test. XRD and FTIR show the presence of graphite, borophosphate; boron oxide and sassolite in the residual char. TGA and DTG disclosed that EG improved the residual mass of coating. XPS analysis showed the char residue of IF5-APP-EG contains carbon and oxygen contents 47.50 and 40.70, respectively. Py-GCMS analysis described that the IF5-APP-EG released less gaseous compounds. The weathering test illustrated that's the char expansion of coatings samples was decreased due to the presence of a humid environment and UV light. The IF5-APP-EG showed the maximum char expansion, lower substrate temperature and high residual weight among the studied formulations.     

Influences of silicone emulsion on fire protection of waterborne intumescent fire-resistive coating

The combination of self-crosslinking polyacrylate emulsion and silicone emulsion was used as a binder for the preparation of waterborne intumescent fire-resistive coatings. The influences of silicone emulsion on fire protection and char formation of the coatings were investigated in detail by means of TGA, SEM, energy dispersive spectroscopy analysis, rheological measurement, and fire protection tests. The results showed that using silicone emulsion improved thermal stability and antioxidation ability of the coating and increased the residue weights of the char layer at high temperature. Furthermore, an appropriate amount of silicone emulsion could improve the rheological property of the mixed binders and be conducive to the increase of the intumescent factor of the coatings, thus improving the fire protection of the coating significantly. However, an excess amount of silicone emulsion can lead to uneven dispersion of silicone emulsion in the mixed binder and cause an uneven distribution of cell size of the char layer.     

钢结构用水性膨胀型防火涂料的制备及性能研究

以高岭土及含锆陶瓷纤维作为增强填料,聚醋酸乙烯酯乳胶和醋叔乳胶的混合液为基料,多聚磷酸铵(APP)、三聚氰胺(MEL)、季戊四醇(PER)为膨胀阻燃体系,开发了一种燃烧后具有高强度膨胀炭层的水性膨胀型防火涂料.研究了乳胶类型、膨胀阻燃体系各组分配比、颜基比、高岭土及含锆陶瓷纤维对水性膨胀型防火涂料性能及炭层强度的影响....     

Comparative study of the fire protection performance and thermal stability of intumescent fire-retardant coatings filled with three types of clay nano-fillers

The fire protection and thermal stability properties of intumescent fire-retardant coatings filled with three various clay nano-fillers (layer double hydroxide [LDH], montmorillonite [MMT], and sepiolite) were compared by fire protection tests and thermo-gravimetric analysis. The fire protection tests show that the incorporation of three fillers improves the fire protection properties of the intumescent fire-retardant coatings and the addition of 1 wt% sepiolite exhibits the lowest flame spread rating of 9.9 and equilibrium backside temperature of 164.5°C at 900 seconds. TG analysis shows that the incorporation of nano-fillers imparts a considerable enhancement of thermal stability and char formation to the intumescent coatings. Especially, the coating with 1 wt% sepiolite acquires the highest residual weight of 34.2% among the samples. Char residue analysis presents that the introduction of clay nano-fillers plays a positive role in enhancing the compactness and anti-oxidation ability of the char residues, and this positive effect as well as the flame-retardant efficiency depends on the types of clay nano-fillers. The three types of layered clay nano-fillers exhibit synergistic flame-retardant effectiveness in the order of sepiolite > MMT > LDH.     

Influence of nano-boron nitride on anti-aging property of waterborne fire-resistive coatings

The influence of nano-boron nitride (BN) with a multilayered structure on the anti-aging property of fire-resistive coatings was studied. After accelerated weathering for 20 days, the thermal stabilities and fire protection of the coating without nano-BN were significantly decreased, but the coating modified by nano-BN still maintained excellent intumescent effect and fire protection. The results indicated that nano-BN could improve the anti-aging property of the coatings remarkably. FTIR and XPS characterizations suggested that nano-BN with a multilayered structure could prevent the migration behavior of the hydrophilic fire-retardant additives and keep the fixed ratio of those additives in the coating. TGA results demonstrated that nano-BN could effectively enhance the thermal stabilities of the aged coatings and improve the anti-oxidation property of the char layers formed by the coatings. XRD and EDS results proved that the anti-oxidation of the aged coatings under high temperature could be enhanced effectively after adding nano-BN. SEM observations illustrated that nano-BN addition was beneficial to the improvement of the foam structure of the aged coating.     

海泡石和可膨胀性石墨对水性超薄膨胀型钢结构防火涂料阻燃性能的影响

采用可膨胀性石墨（EG）和海泡石对传统的APP/PER/MEL膨胀型防火涂料体系进行改性,制备了一种新型水性超薄膨胀型防火涂料,并采用防火性能测试装置、热重分析（TGA）、差热重量分析（DTG）及X射线衍射（XRD）等方法对该防火涂料的耐火性能、热降解过程、碳化层结构进行了研究。热分析结果表明,海泡石与EG复合使用,将充分发挥它们的协同作用：EG在较低温度区域能够延缓碳化层的形成,而海泡石则能够在高温区域阻止碳化层氧化分解,并提高成炭率从而达到阻燃的目的。XRD结果显示,复合使用EG和海泡石能够促进碳化层中TiP2O7的形成,在高温阶段保护碳化层不被氧化。当防火涂料中添加3wt%海泡石和2wt%EG,涂层厚度为1mm时,钢材的耐火时间达到72min。     

Effects of inorganic fillers on the performance of the water-based intumescent fire-retardant coating

The purpose of this research was to evaluate the influences of filler type and its content on the performance of a water-based intumescent fire-retardant coating. Three fillers (vermiculite, celite, and aluminum hydroxide) were added to the intumescent paint formulation. The thermal and fire protective properties were studied with thermogravimetric analysis (TGA), torch test, electrical furnace, scanning electron microscopy (SEM), and Fourier transform infrared analysis (FTIR). The results showed that adding fillers into coatings up to 3% could improve the intumescent coating's behavior and increase its endurance against flames. Of the three fillers used, vermiculite showed a better performance in the torch test, attributed to its chemical and physical structure. Vermiculite has low thermal conductivity and is considered an appropriate filler for heat-insulation. The final back-plate temperatures in the torch test for the vermiculite-containing samples were around 100°C–150°C lower than that of other samples. Moreover, vermiculite's addition improved the coating's expansion by 10% compared with the control sample's. The vermiculite sample's char layer morphology showed a uniform cell size distribution, indicating structural robustness. The coating samples successfully transformed polypropylene flammability from highly flammable to V0 level in the UL 94 vertical burning test standard. The results showed that vermiculite could improve intumescent paint's fire resistance and be used as an enhancer in intumescent coating formulations.     

海泡石和EG对水性膨胀型钢结构防火涂料的影响

采用可膨胀性石墨(EG)和海泡石对传统的APP/PER/MEL膨胀型防火涂料体系进行改性,制备了一种新型水性超薄膨胀型防火涂料,并采用防火性能测试装置、热重分析(TGA)、差热重量分析(DTG)及X射线衍射(XRD)等方法对该防火涂料的耐火性能、热降解过程、炭化层结构进行了研究。热分析结果表明,海泡石与EG复合使用,将充分发挥它们的协同作用:EG在较低温度区域能够延缓炭化层的形成,而海泡石则能够在高温区域阻止炭化层氧化分解,并提高成炭率从而达到阻燃的目的。XRD结果显示,复合使用EG和海泡石能够促进炭化层中TiP2O7的形成,在高温阶段保护炭化层不被氧化。当防火涂料中添加质量分数3%海泡石和质量分数2%EG,涂层厚度为1.0 mm时,钢材的耐火时间达到72 min。     

氧化石墨烯提高钢结构水性膨胀防火涂料的防火性能研究

以水性丙烯酸树脂为基体,聚磷酸胺、季戊四醇和三聚氰胺为膨胀阻燃体系,加入少量氧化石墨烯制备水性膨胀防火涂料。采用小板燃烧法研究了氧化石墨烯用量对膨胀型防火涂料的阻燃性能的影响。结果表明:加入极少量氧化石墨烯(<0.01%),可提高涂料的阻燃性,当氧化石墨烯含量在0.005%时,涂层的耐燃时间可达432 s,炭层膨胀高度较未加氧化石墨烯涂层增加了13.04%。结合红外光谱(FT-IR)、X射线衍射(XRD)和扫描电子显微镜(SEM)等表征手段对炭层形貌进行分析可知,加入氧化石墨烯后炭层在300~500 ℃范围的热稳定性提高,燃烧炭层完整密实,隔热性能提高,耐燃时间提高。     

Influence of nano-boron nitride on fire protection of waterborne fire-resistive coatings

Nano-sized BN and micron-sized BN were used as fillers in fire-resistive coatings. The experimental results suggested that nano-BN with a multilayer structure could remarkably enhance the fire protection of fire-resistive coatings. Turbiscan data indicated that nano-sized BN had better dispersion stability in waterborne coatings than micron-sized BN. TGA results showed that nano-sized BN could enhance the thermal stability of the coatings, especially under high temperature. FTIR and EDS results exhibited that nano-sized BN was helpful in reducing the oxidation degree and enhancing the antioxidation property of the char layer under high temperature. The morphology observation demonstrated that nano-sized BN could improve the foam structure of the char layer so as to improve the mechanical strength of the char layer. Nano-sized BN was helpful for the even distribution of the cells; thus the efficiency of heat insulation of the char layer was enhanced. These results proved that nano-sized BN was beneficial to the forming and expanding of the intumescent char layer, and could provide better fire protection for the coatings.     

A theoretical model for quantifying expansion of intumescent coating under different heating conditions

This article presents an analytical method to calculate the expansion of intumescent coatings under different heating and fire conditions, being the most critical step in quantifying their fire protection performance under different conditions. The proposed method extends that of Amon and Denson, originally developed for spherical bubbles in viscous fluid subject to increase in pressure within the bubbles, to intumescent coatings with non‐uniform temperature field and temperature‐dependent viscosity. The pressure increase inside the bubbles is a result of the conversion of intumescent coatings from melt to gases at high temperatures. The extended analytical method has been used to predict the expansion processes of intumescent coatings tested by Zhang et al. under cone calorimeter with different heating rates and under furnace fire condition with different temperature–time curves, and those of Muller under cone calorimeter heating. In these tests, intumescent coatings were applied to steel plates and the tests examined the effects of different coating thicknesses and steel plate thicknesses, therefore allowing the fire and cone calorimeter tests to encompass a wide range of temperatures and rates of heating. Comparison of the analytical calculation and test results indicates that the proposed method is suitable for quantifying the expansion process of intumescent coatings. POLYM. ENG. SCI., 56:798–809, 2016. © 2016 Society of Plastics Engineers     

Thermal degradation study of fire resistive coating containing melamine polyphosphate and dipentaerythritol

A melamine polyphosphate (MPP)/dipentaerythritol (DPER) mixture was used as fire retardant additives for preparing waterborne intumescent fire resistive coating. The thermal degradation of the MPP/DPER mixture and of the coating was studied by TGA and FTIR. The resulting char of the coating was investigated by XPS, SEM and energy dispersive spectroscopy (EDS). The results showed that the thermal degradation behavior of the MPP/DPER mixture was similar to that of the coating. They decomposed to nonflammable gases, and formed intumescent char layer containing phosphorus oxide at high temperature. The EDS results proved that the resulting char was gradually oxidized with the temperature increase. The SEM micrographs showed that the average cell size of the char layers became bigger and the cell size distribution became wider as the temperature increased from 500 °C to 800 °C, and this non-uniform char layer could damage the fire protection of the coating.     

Expanded polystyrene foams containing ammonium polyphosphate and nano-zirconia with improved flame retardancy and mechanical properties

Expanded polystyrene (EPS) foams were flame retarded using ammonium polyphosphate (APP) and nano-zirconia (nano-ZrO₂) by means of phenolic resin as a binder. It is found that the incorporation of a small amount (5 phr) of nano-ZrO₂ into the APP flame-retarded EPS foams leads to 19% increase in flexural strength and 38% increase in compressive strength. Flame-retardant properties of the flame-retarded EPS foams were investigated by limiting oxygen index (LOI), UL-94 and cone calorimetry test (CCT). The LOI of the APP flame-retarded EPS foams in presence of nano-ZrO₂ is above 31%, and the UL 94 V-0 rating can be reached. The CCT test results indicate that the APP flame-retarded EPS foams containing nano-ZrO₂ have lower peak heat release rate, average effective heat of combustion and average specific extinction area. Moreover, thermal decomposition of the flame-retarded EPS foams was investigated by thermogravimetric analysis (TGA) and the TGA results illustrated clearly that the addition of nano-ZrO₂ into the APP flame-retarded EPS foams leads to an increase in the residual char yield. The reason for the increase is possibly because ZrO₂ may react during combustion process with pyrophosphoric acid produced from the thermal decomposition of APP to form zirconium pyrophosphate (ZrP₂O₇) confirmed by XRD studies of the char, which is helpful to improve the formation of the char. The XPS results showed that the ratio of oxidized carbons in the char increases with the presence of nano-ZrO₂.     

Effects of inorganic fillers on the shear viscosity and fire retardant performance of waterborne intumescent coatings

In the present work, the effects of inorganic fillers on the fire retardant performance of waterborne intumescent coatings are investigated by thermogravimetry (TG), capillary rheometer, X-ray diffraction spectroscopy (XRD) and fire retardant test, etc. The TG results indicate that the thermal stability of vinyl acetate-vinyl ester of versatic acid copolymer (hereafter VAc-VeoVa) in VAc-VeoVa/Si–Al powder composite or in VAc-VeoVa/Halloysite nanometer-tube (HNTs) composite is improved mainly due to the release of the crystal water in Si–Al powder or HNTs. Capillary rheometer analysis results demonstrate that the VAc-VeoVa/HNTs composite melt possesses the highest shear viscosity, because of the large specific surface area of HNTs and the strong interaction force between HNTs and VAc-VeoVa. Weight loss difference (ΔT) of filler/ammonium polyphosphate (APP) composites show antagonism effects at 300 °C < T < 650 °C and synergistic effects at T > 650 °C. The fire retardant test results show the coatings using TiO₂/Si–Al powder/HNTs (8/1/1) as multiple fillers obtains an intumescent char layer with intumescent ratio of 28.14 and presents excellent fire retardant performance (3327 s). It is found that the high melt viscosity, resulted from the effect of inorganic filler, immobilizes the relaxation and rotation of polymer chain, restricts the intumescent behavior of the coatings, which leads to the formation of an intumescent char layer with lower intumescent ratio and the shortening of the fire retardant time. Moreover, the antagonism effect between filler and APP reduces the catalytic dehydration efficiency of pentaerythritol (PER) and VAc-VeoVa, which, as a result, also affects the final fire retardant performance of coatings.     

Study on the preparation and properties of novel transparent fire-resistive coatings

A cyclic polyphosphate (CPPA) was synthesized by the reaction of polyphosphoric acid and pentaerythritol. Polyethylene glycol (PEG) was introduced in the structure of CPPA to improve its solubility in water and ethanol and five kinds of reactive type flame retardants (MCPPA) were obtained. ³¹P NMR, ¹H NMR, FTIR, and TGA were used to characterize the composition and structure of CPPA and MCPPAs. The experimental results showed that there were 25% cyclic P–O–C structures in the product and MCPPA had better carbonization ability than CPPA. Five kinds of transparent fire-resistive coatings were prepared by the mixing of amino resin with five kinds of MCPPAs. The results of the fire protection test showed that both the fire-resistive time of coatings and intumescent factor of char layers decreased with the increase of molecular weight of PEG. The results of TGA and EDS showed that the carbonaceous residue of coatings and the antioxidation ability of char layers also decreased regularly with the increase of molecular weight of PEG. The SEM images demonstrated that the coating prepared with low molecular weight of PEG contributed to dense form structure and narrow distribution of cell size. Above all, the transparent fire-resistive coating prepared with PEG 200 had the best fire retardancy and stable thermal behavior.     

Thermal degradation study of fire resistive coating containing melamine polyphosphate and dipentaerythritol

A melamine polyphosphate (MPP)/dipentaerythritol (DPER) mixture was used as fire retardant additives for preparing waterborne intumescent fire resistive coating. The thermal degradation of the MPP/DPER mixture and of the coating was studied by TGA and FTIR. The resulting char of the coating was investigated by XPS, SEM and energy dispersive spectroscopy (EDS). The results showed that the thermal degradation behavior of the MPP/DPER mixture was similar to that of the coating. They decomposed to nonflammable gases, and formed intumescent char layer containing phosphorus oxide at high temperature. The EDS results proved that the resulting char was gradually oxidized with the temperature increase. The SEM micrographs showed that the average cell size of the char layers became bigger and the cell size distribution became wider as the temperature increased from 500 °C to 800 °C, and this non-uniform char layer could damage the fire protection of the coating.     

Flame retardancy and crack resistance of transparent intumescent fire‐resistive coatings

In this article, dihydroxy polydimethylsiloxane (n = 5–10) was introduced into the structure of polyphosphate (PPE) to get siloxane‐modified polyphosphate (SiPPE). Five kinds of SiPPEs with different Si contents were obtained. FTIR (Fourier Transform Infrared spectroscopy) ICP (Inductively Coupled Plasma Emission Spectroscopy), ³¹P NMR (Nuclear Magnetic Resonance Spectroscopy) and TGA (Thermogravimetric Analysis) were used to characterize the composition and structure of PPE and SiPPEs. Six kinds of transparent fire‐resistive coatings were prepared by the mixing of amino resin with PPE and five kinds of SiPPEs. The results of the fire protection test showed that both the fire‐resistive time of coatings and intumescent factor of char layers increased with the increase in content of Si. The results of TGA demonstrated that the carbonaceous residue of coating also increased regularly. The hardness, flexibility, digital photos, SEM (Scanning Electronic Microscopy) and other testing results showed that the introduction of silicon oxygen segment can effectively improve the crack resistance. The charcoal layer structure was more solid than before and collapse was not obvious after long time flame shock. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42423.     

水性超薄膨胀型钢结构防火涂料的制备

以有机硅改性的丙烯酸酯乳液为基料,多聚磷酸铵(APP)、季戊四醇(PER)、三聚氰胺(MEL)为膨胀阻燃体系,制备水性超薄膨胀型钢结构防火涂料;采用硼酸和可膨胀石墨(EG)改性防火涂料。研究表明,同时用w(硼酸)=4%,w(EG)=5%改性防火涂料,涂层的耐火极限达到93 min,热失质量分析(TGA)测试表明w(硼酸)=4%,w(EG)=5%共同改性的防火涂料在700℃时最终残炭量是44%。扫描电镜(SEM)分析结果表明硼酸/EG改性的残炭层形成了致密的"蜂窝"状结构。