On a planar thermal analysis of intumescent coatings

The paper discusses a complex model for a nonstationary planar thermal analysis of expandable intumescent coatings. Following the existing one‐dimensional models, we develop novel and improved equations for the two‐dimensional thermal analysis of intumescent coatings. A progressive expansion due to chemical reactions, phase changes, and the time and temperature‐dependent thermal properties of the coating are considered. In the heating process, the coating may locally experience virgin, intumesced, or charred phases, and their transition with time. The rate of the density loss due to the pyrolysis reaction is described with the Arrhenius equation. The thickness of the coating is assumed to increase enormously during the pyrolysis. Consequently, the energy and mass equilibrium equations are formulated with respect to both the deformed and undeformed configuration. Since most of material properties of commercial products are not given by manufacturers, an innovative procedure is proposed to determine the time‐dependent thermal conductivities and remaining fundamental properties of the coating from the set of measured temperatures. This, together with the two‐dimensional formulation of the thermal equations with respect to the undeformed configuration, makes the present model unique and appropriate for the thermal analyses of an arbitrary steel cross section protected with intumescent coatings.     

膨胀型防火涂料的研究进展

综述了膨胀型防火涂料的发展历程、分类、制备工艺流程及其阻燃机理。对膨胀型防火涂料基体树脂和各种防火助荆（包括成碳剂、脱水成碳催化剂、发泡剂、防火填料和颜料及其它助剂等）的选择方法进行了分析,指出了膨胀型防火涂料的发展动向。     

Bio‐hybrid nanocomposite coatings from sonicated chitosan and nanoclay

Nanocomposite films and coatings with improved properties were produced from ultrasonic dispersed chitosan and hydrophilic bentonite nanoclay. Bio‐hybrid coatings were applied onto argon–plasma‐activated LDPE coated paper. The intercalation of chitosan in the silicate layers was confirmed by the decrease of diffraction angles as the chitosan/nanoclay ratio increased. Nanocomposite films and multilayer coatings had improved barrier properties against oxygen, water vapor, grease, and UV‐light transmission. Oxygen transmission was significantly reduced under all humidity conditions. In dry conditions, over 99% reduction and at 80% relative humidity almost 75% reduction in oxygen transmission rates was obtained. Hydrophilic chitosan was lacking the capability of preventing water vapor transmission, thus total barrier effect of nanoclay containing films was not more than 15% as compared with pure chitosan. Because to very thin coatings (≤1 μm), nanoclay containing chitosan did not have antimicrobial activity against test strains. All coating raw materials were “generally recognized as safe” (GRAS) and the calculated total migration was in all cases ≤6 mg/dm², thus the coatings met the requirements set by the packaging legislation. Processing of the developed bio‐hybrid nanocomposite coated materials was safe as the amounts of released particles under rubbing conditions were comparable with the particle concentrations in a normal office environment. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Engineering model for intumescent coating behavior in a pilot‐scale gas‐fired furnace

In the event of a fire, intumescent fire protective coatings expand and form a thermally insulating char that protects the underlying substrate from heat and subsequent structural failure. The intumescence includes several rate phenomena, which have been investigated and quantified in the literature for several decades. However, various challenges still exist. The most important one concerns mathematical model validation under realistic exposure conditions and/or time scales. Another is the simplification of advanced models to overcome the often‐seen lack of a complete set of input and adjustable model parameters for a given coating, thereby providing models for industrial applications. In this work, these two challenges are addressed. Three experimental series, with an intumescent coating inside a 0.65 m³ gas‐fired furnace, heating up according to so‐called cellulosic fire conditions, were conducted and a very good repeatability was evident. The experiments were run for almost 3 h, reaching a final gas temperature of about 1100°C. Measurements include transient temperature developments inside the expanding char, at the steel substrate, and in the mineral wool insulation placed behind the substrate. A mathematical model, describing the intumescent coating behavior and temperatures in the furnace using a single overall reaction was developed and validated against experimental data. By including a decomposition front movement through the char, a good qualitative agreement was obtained. After further validation against experiments with other coating formulations, it has potential to become a practical engineering tool. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3947–3962, 2016     

Fire‐resistant elastomers

The molecular design of semi‐inorganic polymers has produced polysilphenylene–siloxane and polyphosphazene elastomers having comparable fire safety to heat resistant engineering plastics. In flaming combustion a polyphosphazene rubber had a four times lower peak heat release rate than the polyurethane elastomer currently used in fire‐blocked aircraft seat cushions. The addition of expandable graphite flakes to polyurethane and polyphosphazene elastomers reduces their peak heat release rates by factors of seven and five, respectively. Published in 2003 by John Wiley & Sons, Ltd.     

钢结构防火涂料配方的响应面法优化

引言钢结构建筑的防火历来是备受业界关注的领域,在众多保护措施当中,防火涂料因其施工方便,不受钢结构形状、面积限制,防火性能优异等优点而在钢结构建筑中广泛使用。其中超薄膨胀型钢结构防火涂料具有粒度细、涂层薄、施工方便和装饰性好等特点,能在满足钢结构防火要求的同时     

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.     

Assessing the performance of intumescent coatings using bench‐scaled cone calorimeter and finite difference simulations

A method was developed to assess the heat insulation performance of intumescent coatings. The method consists of temperature measurements using the bench‐scaled experimental set‐up of a cone calorimeter and finite difference simulation to calculate the effective thermal conductivity dependent on time/temperature. This simulation procedure was also adapted to the small scale test furnace, in which the standard time–temperature curve is applied to a larger sample and thus which provides results relevant for approval. Investigations on temperature and calculated effective thermal conduction were performed on intumescent coatings in both experimental set‐ups using various coating thicknesses. The results correspond to each other as well as showing the limits of transferability between both fire tests. It is shown that bench‐scaled cone calorimeter tests are a valuable tool for assessing and predicting the performance of intumescent coatings in larger tests relevant for approval. The correlation fails for processes at surface temperatures above 750°C, which are not reached in the cone calorimeter, but are attained in the small scale furnace set‐up. Copyright © 2006 John Wiley & Sons, Ltd.     

Synthesis of flame retardant polyester‐urethanes and their applications in nanoclay composites and coatings

This paper describes the synthesis of phosphorus‐containing polyester‐urethanes and their applications in nanoclay composites and coatings. Polyester was prepared by the reaction of bis(bisphenol‐A) monophenyl phosphonate, maleic anhydride and phthalic anhydride. The polyester was reacted with various diols such as ethylene glycol, diethylene glycol and propylene glycol to obtain polyester polyols. Synthesized polyester polyols were characterized by chemical analysis and instrumental analysis and was used further to react with different isocyanates to develop polyester‐urethanes. The synthesized polyester‐urethanes were blended with organo‐modified montmorillonite nanoclay (1 wt%, 3 wt% and 5 wt%) and were cast in a mold and coated on mild steel panels. The thermal stability of neat polyester‐urethane and the nanoclay composites was determined by thermogravimetric analysis. The flame retardant properties of cast films and their composites were determined by the limiting oxygen index and UL‐94 test methods. The physical and mechanical properties of coatings such as pot life, drying properties, scratch hardness, pencil hardness, impact resistance, adhesion and flexibility were investigated. The chemical resistance properties of the coatings were also determined in different reagents. The data reveal that the polyester‐urethane nanoclay composites with 3 wt% clay hold promise for use in effective flame retardant coatings. © 2013 Society of Chemical Industry     

Analysis of tensile modulus of PP/nanoclay/CaCO3 ternary nanocomposite using composite theories

The tensile modulus of PP/nanoclay/CaCO₃ hybrid ternary nanocomposite was analyzed using composite models. Rule of mixtures, inverse rule of mixtures, modified rule of mixtures (MROM), Guth, Paul, Counto, Hirsch, Halpin–Tsai, Takayanagi, and Kerner–Nielsen models were developed for three‐phase system containing two nanofillers. Among the studied models, inverse rule of mixtures, Hirsch, Halpin–Tsai, and Kerner–Nielsen models calculated the tensile modulus of PP/nanoclay/CaCO₃ ternary nanocomposite successfully compared with others. Furthermore, the Kerner–Nielsen model was simplified to predict the tensile modulus by volume fractions of nanofillers. Also, Takayanagi model was modified for the current ternary system. The developed Takayanagi model can predict the tensile modulus using Young's modulus and volume fractions of matrix and nanofillers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Nonisothermal crystallization and melting behavior of PP/nanoclay/CaCO3 ternary nanocomposite

Nonisothermal crystallization and melting behavior of PP/nanoclay/CaCO₃ ternary nanocomposite were investigated using different melt flow index (MFI) of PP, nanoclay and CaCO₃ contents. The rate of crystallization was also studied using relative crystallinity as a function of temperature and time. The results show that the increase of MFI of PP and CaCO₃ content in the prepared ternary nanocomposite shift the crystallization curve of PP to the higher temperature. However, increasing the content of nanoclay from 2 wt % to 6 wt % decreases the crystallization temperature possibly due to the restriction of molecular chain mobility. Further analysis of nonisothermal crystallization was carried out based on Avrami equation which the crystallization kinetic of prepared nanocomposite was evaluated. Except the significant variation in the heat of melting, the influence of these parameters on the melting behavior was much less than the crystallization process. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

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。     

Interaction of a phosphorus‐based FR,a nanoclay and PA6—Part 1: Interaction of FR and nanoclay

The thermal decomposition of organophosphorus fire‐retardant (OP1311) and/ or organonanoclay (Cloisite 30B) is hereby investigated employing thermogravimetric analysis (TGA), to give an insight into their intrinsic behaviour and interaction in polymer nanocomposites for fire safety applications, because the addition of OP1311 and Cloisite 30B in Polyamide 6 (PA6) seems to have a synergistic effect on the thermal decomposition of PA6 (part 2 of the paper). An important objective of this research was to determine to what extent phosphorus components escape in the gaseous phase, which will affect the heat of combustion of the fire‐retarded polymer. The decomposition products arising from pyrolysis and combustion are investigated by means of Fourier transform infrared spectroscopy. Under pyrolytic conditions, the inclusion of Cloisite 30B into OP1311 (FR) shows a synergistic effect on the initial mass loss at low temperature of ～280–420°C and leads to the acceleration of the thermal degradation process. While the DTG curve of Cloisite 30B shows two distinct degradation peaks (steps) that of OP1311 and OP1311 plus Cloisite 30B show four degradation steps. TGA measurements of OP1311 in nitrogen show more mass loss than in air, whereas Cloisite 30B gives similar amounts of mass loss in air and nitrogen. In nitrogen, the major evolved gaseous species from Cloisite 30B alone are hydrocarbons, 2‐(diethylamino)ethanol and water, whereas the evolved gases from that of OP1311 at ～320°C are mainly water, at ～420°C, carbon dioxide, water and ammonia and at 480–570°C diethylphosphinic acid. Under thermo‐oxidative conditions, the gases evolved are mainly carbon dioxide and water from both Cloisite 30B and OP1311. Copyright © 2009 John Wiley & Sons, Ltd.     

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     

Fire‐resistant cyanate ester–epoxy blends

The cure chemistry, thermal stability and fire behaviour of a series of fire‐resistant cyanate ester–epoxy blends were examined. The dicyanate and diepoxide of 1, 1‐dichloro‐2, 2‐bis(4‐hydroxyphenyl)ethylene (bisphenol‐C, BPC) were combined in various molar ratios and the reaction chemistry was monitored using Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The fire behaviour of the BPC cyanate–epoxy blends was studied in flaming and non‐flaming combustion, using OSU calorimetry and pyrolysis‐combustion flow calorimetry (PCFC), respectively. Published in 2003 by John Wiley & Sons, Ltd.     

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.     

膨胀型饰面防火涂料现状及进展

简要介绍了膨胀型饰面防火涂料的阻燃原理和分类。阐述了我国饰面型防火涂料的发展现状及最新科研成果,比较国内外饰面型防火涂料的标准,同时对国内新旧标准的变化进行简要的比较。最后,对我国膨胀型饰面防火涂料的发展趋势进行了展望。     

Performance of corrosion protective epoxy blend-based nanocomposite coatings: a review

ABSTRACT

Epoxy is a thermosetting polymer with exceptional mechanical robustness, thermal stability, and chemical resistance. This article is devoted to updating development, processing, and physicochemical characterizations of epoxy-based anti-corrosion coatings. Incorporation of different polymers in epoxy matrix has motivated extensive research progress in the field of corrosion protection. Epoxy has been blended with polyaniline, polypyrrole, polythiophene, polyamide, polyester, polyurethane, poly(vinyl alcohol), and polydimethylsiloxane to form corrosion protective coatings. The addition of conducting polymer and nanofiller to epoxy matrix modified the nanocomposite morphology and facilitated the development of passive layer at metal/polymer interface. Consequently, nanocomposite coatings act as physical barrier to hinder the penetration of corrosive ions. Likewise, fine dispersion of nanocarbon and inorganic nanoparticles in compatible blends of epoxy/polyamide, epoxy/polyester, epoxy/polyurethane, and epoxy/poly(vinyl alcohol) has resulted in improved adhesion, wear, barrier and anticorrosion properties of the nanocomposite coatings. Design of epoxy blend-based nano-architectures may facilitate appropriate tailoring of overall performance of the resulting anti-corrosion coatings for advance technical applications including aerospace, automotive, construction, electronic devices, and biomedical relevances. New processing techniques may overcome challenges toward high performance future epoxy-based coatings.     

Effects of Ni content on microstructure,mechanical properties and Inconel 718 cutting performance of AlTiN-Ni nanocomposite coatings

AlTiN-Ni coatings with various Ni contents (0–3?at%) were deposited using cathodic arc evaporation. X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, a nanohardness tester, scratch-adhesion tester, and cutting tester were used to examine the microstructure, mechanical properties, and cutting performance of the coatings. The AlTiN coatings exhibited a columnar structure, while the AlTiN-Ni coatings exhibited a nanocrystal structure due to the formation of nc-AlTiN/Ni nanocomposite coatings. The nanohardness of the AlTiN-Ni coatings decreased from 26.2?GPa to 20.9?GPa as the Ni content increased from 0 to 3?at%. At an Ni content of 1.5?at%, the coating possessed a high toughness and sufficient adhesion strength; however, these dropped drastically for the AlTiN-Ni coating with 3?at% Ni owing to the presence of amorphous Ni. The results for the Inconel 718 turning indicated that the wear mode is adhesion at the rake face, abrasion and adhesion (built-up edge) at the flank face, and chipping at the cutting edge. Compared to AlTiN-Ni₃ and AlTiN-coated tools, the lifetime of the AlTiN-Ni_1.5 coated tool increased to 160% at a cutting speed of 40?m/min. This was attributed to less adhesion at the rake face and chipping at the cutting edge, due to the nanocrystal structure and higher toughness of the AlTiN-Ni_1.5 coating.     

Experimental study on insulative properties of intumescent coating exposed to standard and nonstandard furnace curves

This paper reports the results of an experimental study on two types of intumescent coating exposed to the ISO834 standard fire and three nonstandard fire curves. The nonstandard fires were all less severe than the standard fire. A total of 72 intumescent coating protected steel specimens were tested. The expanded thickness of intumescent char was measured, and the pore feature was observed. Constant thermal conductivity for each specimen was calculated based on the measured steel plate temperature. Thermogravimetric analysis (TGA) test was carried out, and the results show that more gas is trapped within the coating due to better matching of thermal behaviour between gas evolution and polymer viscosity as the rate of heating increases. The constant effective thermal conductivities for the intumescent coating under the nonstandard fires were 65% (type‐W) and 35% (type‐S) higher than that under the standard fire, which resulted in an overestimation of the coating failure time up to 15 and 11 minutes, respectively. Therefore, it is sometimes insecure to use results from standard fire tests guiding the design of coating thickness for steel elements under nonstandard fire conditions.