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     

Testing fire protective properties of intumescent coatings by in-line temperature measurements on a cone calorimeter

An experimental setup was proposed for evaluating the thermal shielding efficiency of intumescent coatings. In particular, a cone calorimeter as heater source was coupled with a thermocouple as detector of the temperature of steel plates coated with intumescent coatings. According to ENV 13381-4 test procedure, the heating curves of the setup was measured by plate thermocouple and compared with ISO 834 standard curve. Meanwhile, the comparison was also made between temperature profiles of blank steel plates at different heat fluxes and unprotected steel elements under ISO fire. The possible correlation between bench scale and large scale test was hence discussed. Several factors (heat flux, distance to cone heater, coating thickness, sample size, edge effect and heat insulator) were deeply investigated and discussed: significant relationships between these parameters and the thermal protective properties of the intumescent coating were evidenced; furthermore a fully developed intumescent char could be obtained by controlling the aforementioned parameters. As a conclusion, the proposed bench-scale test was found to be comparable to the large scale test only in the early heating stages.     

Investigation of fire behavior of rigid polyurethane foams containing fly ash and intumescent flame retardant by using a cone calorimeter

Cone calorimeter is one of the most useful bench‐scale equipment which can simulate real‐world fire conditions. Therefore, cone calorimeter tests have been the most important and widely used tests for research and development of fire behavior of polymeric materials. In this study, fire behavior of rigid polyurethane foams containing fly ash (up to 5 wt %) and intumescent flame retardant (up to 5 wt %) composed of ammonium polyphosphate/pentaerythritol was investigated by using a cone calorimeter. In addition, thermogravimetric analysis of the additives and the foams were also carried out to explain the effects of fly ash and intumescent flame retardant on fire behavior of the foams. Experimental results indicated that rigid polyurethane foam containing fly ash and the intumescent flame retardant in comparison with pure rigid polyurethane foam shows significantly enhanced fire resistance and thermal stability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Influence of external heat flux and coating thickness on the thermal insulation properties of two different intumescent coatings using cone calorimeter and numerical analysis

Polymeric intumescent coatings are fire protective materials that increase their thermal resistance when exposed to high temperatures to prevent building structures from damage. The idea of the investigation was to develop a simple test method to determine the time dependent thermal conductivity of intumescent coatings. Therefore steel plates were coated with two different intumescent systems. During cone calorimeter tests the temperature at the back side of the coated plates was measured. These results were used to calculate the time dependent thermal resistance of the protective layer with the simulation program IOPT2D for different external heat fluxes and different layer thickness. Copyright © 2003 John Wiley & Sons, Ltd.     

Effects of natural weathering on the fire properties of intumescent fire‐retardant coatings

Fire‐retardant coatings could be one option for providing enhanced protection to buildings during a wildfire, particularly when applied to combustible siding and in under‐eave areas. Limited studies have been conducted on their effectiveness but maintaining adequate performance after weathering has been questioned. This paper reports on a study evaluating the effect of natural weathering on the performance of intumescent‐type fire‐retardant coatings. The main concerns were (a) the reduction of ignition resistance of the coating after weathering and (b) the coating might contribute as a combustible fuel and assist the fire growth after weathering. This study evaluated the performance of 3 intumescent coatings that were exposed to natural weathering conditions for up to 12 months. A bench‐scale evaluation using a cone calorimeter was used to evaluate the performance of the coatings at 3 heat flux levels (30, 50, and 70 kW/m²). Our results showed that weathering exposure reduced the effectiveness of fire protection of intumescent coatings, but the weathered coatings did not act as additional fuels. Weathering orientation showed much less effect on the performance of intumescent coatings in comparison to other parameters. There was statistical evidence that weathering duration, heat flux level, and coating type affected the combustion properties.     

Experimental and numerical study of burning behaviors of flaxboard with intumescent coating and nanoparticles in the cone calorimeter and single burning item tests

This paper presents an experimental and numerical investigation of the effects of intumescent coating and nanoparticles on the burning behaviors of flaxboard. Virgin flaxboard samples and those coated with intumescent coatings (with/without nanoparticles) were tested in the cone calorimeter and single burning item (SBI) test. Experimental results show a significant increase in the time to ignition and also a reduction in the heat release rate by the intumescent coatings. In order to explain quantitatively and predict the effects of the intumescent coating, a global fractional factor (the ratio of the heat flux at the interface of the intumescent surface and the char layer of flaxboard to the surface heat flux when there is no intumescent coating layer) was introduced based on analytical solutions for charring materials. The fractional factor for the intumescent coatings was found by comparing predictions to the experimental data in the cone calorimeter test and, subsequently, was incorporated in an upward flame spread model, along with the ignition and thermal properties deduced from the ignition tests, to predict the burning rates in the SBI tests. Copyright © 2011 John Wiley & Sons, Ltd.     

Revealing the inner secrets of intumescence: Advanced standard time temperature oven (STT Mufu+)—μ‐computed tomography approach

Intumescent coatings have been used for fire protection of steel for decades, but there is still a need for improvement and adaptation. The key parameters of such coatings in a fire scenario are thermal insulation, foaming dynamics, and cohesion. The fire resistance tests, large furnaces applying the standard time temperature (STT) curve, demand coated full‐scale components or intermediate‐scale specimen. The STT Mufu⁺ (standard time temperature muffle furnace⁺) approach is presented. It is a recently developed bench‐scale testing method to analyze the performance of intumescent coatings. The STT Mufu⁺ provides vertical testing of specimens with reduced specimen size according to the STT curve. During the experiment, the foaming process is observed with a high‐temperature endoscope. Characteristics of this technique like reproducibility and resolution are presented and discussed. The STT Mufu⁺ test is highly efficient in comparison to common tests because of the reduced sample size. Its potential is extended to a superior research tool by combining it with advanced residue analysis (μ‐computed tomography and scanning electron microscopy) and mechanical testing. The benefits of this combination are demonstrated by a case study on 4 intumescent coatings. The evaluation of all collected data is used to create performance‐based rankings of the tested coatings.     

茶皂素基膨胀型阻燃剂的制备及其在涂料中的应用

采用多羟基、多羧基的活性天然产物茶皂素为原料,与聚磷酸铵和季戊四醇在一定条件下反应,制备一种聚磷酸酯类茶皂素基三位一体新型环保膨胀型阻燃剂。采用傅里叶红外分析技术对阻燃剂进行了结构表征,采用综合热分析仪对阻燃剂的热降解性能进行了研究。结果表明,茶皂素与聚磷酸铵、季戊四醇发生反应,生成聚磷酸酯类茶皂素基膨胀型阻燃剂,且该阻燃剂具有良好的热稳定性,降解热释放较小,高温残留率高,最终的质量残留率高达30.77%。将制备阻燃剂用于阻燃涂料中,并采用氧指数测试仪和锥形量热仪研究了阻燃涂料的阻燃性能和热解性能。研究表明,茶皂素基三位一体膨胀型阻燃剂能显著提高涂料的阻燃性能,阻燃涂料的氧指数值高达34.2%,耐火时间为11.1 min,且锥形量热实验中,该阻燃涂料试样的平均热释放速率（m-HRR）为36.18 kW/m2,总热释放量（THR）为5.25 kJ/m2,平均有效燃烧热（m-EHC）为5.11 kJ/kg,与含复合型阻燃剂的阻燃涂料试样相比,阻燃性能得到极大提高。该制备阻燃剂不含卤素,集三源一体,具有阻燃性能优越,相容性能良好,高效环保等优点。     

Experimental study on polystyrene with intumescent flame retardants from different scale experiments

In this study, the fire performance and toxicity of intumescent flame retardant (IFR) polystyrene composites were investigated experimentally. Ammonium polyphosphate, pentaerythritol, and melamine were selected as IFR. The flammability of the polystyrene (PS) composites was evaluated by microscale combustion calorimetry and cone calorimetry and in the ISO Room. The results suggested that the thermal stability and the peak heat release rate of PS composites decreased with the increasing content of IFR. In the cone calorimeter and ISO 9705 testing, the carbon monoxide yield of PS composites also decreased markedly with the addition of IFR. Scanning electron microscope images show that the char from cone calorimetry testing was more compact and smoother than that from the ISO 9705 testing. The comparison between bench‐ and full‐scale tests demonstrated that the flammability and the toxicity of PS composites are decreased markedly due to the incorporation of the flame retardant, but considerable differences exist. Copyright © 2014 John Wiley & Sons, Ltd.     

Bench Scale Tests on Controlling Plastic Fires with Water Mists

Bench scale tests are proposed to study the performance of a water mist fire suppression system on plastic fires. The effects of water mist on burning solid polymethylmethacrylate (PMMA) and polyvinylchloride (PVC) are compared with a cone calorimeter. A scaled nozzle developed earlier for discharging water mist in a cone calorimeter was used. Operating pressures of 0.2–0.7 MPa, corresponding to water flow rates of 68 mL/min and 134 mL/min, were used. It was observed that PMMA samples could be ignited easily and liberated significant amounts of heat at high release rates. PVC was more difficult to ignite, but gave out large quantities of smoke. Discharging water to both did not increase the heat release rate significantly. However, both smoke quantity and carbon monoxide concentration increased. This was more obvious for PMMA fires. Hazard assessment parameters for thermal aspects and smoke were measured and presented as a ‘hazard diagram' to understand the action of water mist and the potential for re‐ignition. It is suggested that bench scale tests can also give useful results for designing water mist systems. The discharging time of water mist is a key factor in controlling PMMA fires. If the discharging time is not long enough, re‐ignition might occur once the discharging of water stops.     

Development of fire‐retarded materials—Interpretation of cone calorimeter data

There is little consensus within the fire science community on interpretation of cone calorimeter data, but there is a significant need to screen new flammability modified materials using the cone calorimeter. This article is the result of several discussions aiming to provide guidance in the use and interpretation of cone calorimetry for those directly involved with such measurements. This guidance is essentially empirical, and is not intended to replace the comprehensive scientific studies that already exist. The guidance discusses the fire scenario with respect to applied heat flux, length scale, temperature, ventilation, anaerobic pyrolysis and set‐up represented by the cone calorimeter. The fire properties measured in the cone calorimeter are discussed, including heat release rate and its peak, the mass loss and char yield, effective heat of combustion and combustion efficiency, time to ignition and CO and smoke production together with deduced quantities such as FIGRA and MARHE. Special comments are made on the use of the cone calorimeter relating to sample thickness, textiles, foams and intumescent materials, and the distance of the cone heater from the sample surface. Finally, the relationship between cone calorimetry data and other tests is discussed. Copyright © 2007 John Wiley & Sons, Ltd.     

Experimental investigation and numerical modelling of the fire performance for epoxy resin carbon fibre composites of variable thicknesses

This paper applies a unique integrated approach to determine the flammability properties of a composite material (epoxy with carbon fibre) and compares its fire behaviour at two different thicknesses (2.1 and 4.2 mm) by performing small scale (thermo‐gravimetric analysis (TGA)/Fourier transform infrared radiation) and meso‐scale tests (cone calorimeter). For small‐scale tests, experiments were conducted in nitrogen using TGA coupled to gas analysis by Fourier transform infrared radiation. These results allow the determination of thermal stability, main degradation temperature and main gaseous emissions released during the thermal degradation. For meso‐scale tests, experiments were carried out using a cone calorimeter with sample dimensions of 100 × 100 mm at five heat fluxes (30, 40, 50, 60 and 70 kW/m²). The results show that the ignition time increases with an increase in the thickness of the material. Relative hazard classification of the fire performance of the current composites has also been compared with other materials using parameters obtained elsewhere. In addition, the effective ignition, thermal and pyrolysis properties obtained from the ignition and mass loss rate experiments for the 4.2‐mm thick samples were used in a numerical model for pyrolysis to predict well ignition times, back‐surface temperatures and mass pyrolysis rates for all heat fluxes as well as for the 2.1‐mm thick samples. Note that the ignition temperature obtained in the cone agrees with the main degradation temperature in the TGA. The flammability properties deduced here can be used to predict the heat release rate for real fire situations using CFD modelling. Copyright © 2016 John Wiley & Sons, Ltd.     

Mg（OH）2／Al（OH）3对膨胀型防火涂料热分解特性影响的研究

以苯丙乳液为成膜物质,聚磷酸铵、三聚氰胺、季戊四醇为膨胀阻燃体系,分别添加不同量的氢氧化镁、氢氧化铝制备了三种防火涂料。用热重分析仪分别对膨胀阻燃涂料的单组分及涂料的热分解特性进行表征,并用锥形量热仪测试其燃烧性能。实验结果表明,单独用氢氧化镁或氢氧化铝作为添加剂,均会促进涂料的热分解过程,其热释放速率的峰值也会提前。     

New fire‐protective intumescent coatings for wood

Polyurethane coatings are highly flammable, and because of their widespread applications on different substrates (wood, steel, and building materials), there is a need to increase their fire‐safety properties. Intumescent additives sharply suppress the flammability properties of polyurethane coatings. Two problems accompany intumescent additives: their high loading percentage and incompatibility with polyurethane coatings. In this research, we succeeded in increasing the compatibility by mixing intumescent additives with a butyl acrylate polymer and in lowering the flame‐retardant additive loading (up to 20%) by incorporating newly modified montmorillonite. The flammability properties of the new intumescent coatings were characterized with a cone calorimeter. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Heat release rate and computer fire modelling vs real‐scale fire tests in passenger trains

The materials and products used in passenger trains may not be the first ignited element, but during the fire development, these materials, especially ceiling linings and wall coverings, contribute significantly to the fire growth. The fire safety requirements in passenger trains consist mainly of bench‐scale tests, with particular focus on the sample geometry, position and fire exposition. When this information is extrapolated to real end use conditions limitations appear. In this paper, a discussion of the use of fire dynamics simulator model and heat release rate experiments in cone calorimeter (bench‐scale test) is presented in order to represent the fire development in a passenger train compartment. For the study, two fire scenarios were selected: (1) the single burning item SBI test (modified) and (2) a passenger train compartment. Initially, the limitations of the assumptions and hypothesis made when producing the model were analyzed and the research team carried out a sensitivity study of the model results considering different grid sizes. In order to validate the model, both bench‐ and full‐scale fire tests were considered based on the results provided by the European research program FIRESTARR. The limitations and uncertainties in the results demonstrate the importance of two basic factors: the incident heat flux in the cone calorimeter tests and the prescribed ignition temperature. Copyright © 2008 John Wiley & Sons, Ltd.     

Fire calorimetry relying on the use of the fire propagation apparatus. Part I: early learning from use in Europe

The fire propagation apparatus (FPA) is the bench scale fire calorimeter that was recently described in its updated version in ASTM E 2058. The apparatus was originally developed in the USA by Tewarson and co‐workers from the mid 1970s, under the name ‘50 kW lab‐scale flammability apparatus’, and is therefore still known in Europe as the ‘Tewarson apparatus’. The paper focuses on the experience achieved so far with the first modern version of the apparatus implemented in Europe (France). Part I in this series of articles reports on the main results achieved during the commissioning period of the apparatus. In a first step, preliminary experiments were carried out in order to check and calibrate different sub‐equipment of the calorimeter. The results are principally presented for the load cell system and the infrared heating system which are essential pieces of sub‐equipment. In a second step, a set of fire tests using methane or acetone as fuel was carried out in order to check and calibrate the overall working of the calorimeter in well‐fire conditions. The performance of the calorimeter was also checked when it operates in under‐ventilated fires. Relevant testing procedures and potential technical problems are discussed. A set of recommendations are derived from the early learning obtained at the INERIS fire laboratory in order to check the consistency of the results obtained from bench‐scale fire tests. These recommendations are thought to be applicable to all types of bench scale fire calorimeters. Copyright © 2005 John Wiley & Sons, Ltd.     

Linking the flame‐retardant mechanisms of an ethylene‐acrylate copolymer,chalk and silicone elastomer system with its intumescent behaviour

In this paper the flame‐retardant mechanisms of a flame‐retardant system consisting of ethylene‐acrylate copolymer, chalk and silicone elastomer are linked to its foaming process and to its formation of a final intumescent structure. Thermocouples were placed inside and at the surface of cone calorimeter test specimens in order to measure the temperature at different depths during the formation of the intumescent structure. The temperature and visual observations of the foaming process were then linked to chemical reactions seen with thermogravimetric analysis and also coupled with earlier knowledge of the flame‐retardant mechanism. A correlation is seen between the chemical reactions, the temperature (inside and at the surface of a cone calorimeter test specimen) as measured by thermocouples and visual observations in the intumescent process. Further, the outcome of this study provides useful information for achieving a deeper understanding of the flame‐retardant mechanisms of the ethylene‐acrylate copolymer, chalk and silicone elastomer system. Copyright © 2005 John Wiley & Sons, Ltd.     

Polyurethane coatings based on linseed oil phosphate ester polyols with intumescent flame retardants

The effect of intumescent flame retardants on the properties of polyurethane (PU) coatings based on 2 kinds of phosphate ester polyol was studied. Synthesizing polyols, phosphorylation of epoxidized linseed oil with phosphoric acid was performed in the presence of isopropyl alcohol (IPA polyol) or diethylene glycol butyl ether (DGBE polyol). The obtained polyols were characterized by Fourier transform infrared (FTIR) and ³¹P nuclear magnetic resonance (NMR) spectroscopy. The properties of neat PU coatings based on 2 polyols and those filled with different content (up to 25 wt%) of melamine (Mel), ammonium polyphosphate (APP), and expandable graphite (EG) were studied using thermal gravimetric analysis (TGA), and tensile and cone calorimeter tests. It was found that IPA polyol contained not only phosphate monoesters and diesters, as DGBE polyol, but also phosphate triester and pyrophosphate monoester. Due to this difference, IPA neat and filled coatings had higher tensile characteristics and char residue in a TGA test. Also, the flame retardancy of IPA coatings, compared with that of DGBE coatings, was higher. In a cone calorimeter test, coatings filled with Mel showed a small increase of flame retardancy, but the total smoke release (TSR) of wood samples with coatings decreased noticeably. The effect of APP on the flame retardancy of coatings was higher, but in contrast, the TSR of samples increased with increasing APP content. Even greater decrease of flammability parameters and a simultaneous significant decrease of TSR were shown by the samples with IPA coatings filled with EG.     

紫外老化对溶剂型膨胀防火涂料基本性能的影响

膨胀型钢结构防火涂料的耐候性是其应用中需考虑的一个重要因素。本文利用扫描电镜（ SEM）、热重分析仪（ TG）和小型耐火试验炉研究了紫外老化对膨胀型防火涂料的磷含量、表面形貌、热稳定性和防火性能的影响规律,并研究了面漆对其上述性能的影响。研究结果表明：随紫外老化试验的进行,防火涂料的磷含量、热稳定性、高温膨胀成炭性能和耐火隔热性能均出现明显降低;面漆具有较好的保护作用,表面涂刷面漆的防火涂料各项性能变化不大。     

Assessing the reaction to fire of cables by a new bench‐scale method

The recently approved EU Construction Products Regulation (CPR) applies to cables as construction products. The difficulty of predicting the fire performance of cables with respect to propagation of flame and contribution to fire hazards is well known. The new standard EN 50399 describes a full‐scale test method for the classification of vertically mounted bunched cables according to CPR. Consideration of the material, time, and thus cost requires an alternative bench‐scale fire test, which finds strong demand for screening and development purposes. The development of such a bench‐scale fire test to assess the fire performance of multiple vertically mounted cables is described. A practical module for the cone calorimeter is proposed, simulating the fire scenario of the EN 50399 on the bench scale. The efficacy of this module in predicting full‐scale CPR test results is shown for a set of 20 different optical cables. Key properties such as peak heat release rate (PHRR), fire growth rate (FIGRA), and flame spread are linked to each other by factors of around 5. In a case study, the bench‐scale test designed was used to investigate the influence of the main components on the fire behaviour of a complex optical cable. Copyright © 2016 John Wiley & Sons, Ltd.