Investigation of char strength and expansion properties of an intumescent coating exposed to rapid heating rates

An efficient and space saving method for passive fire protection is the use of intumescent coatings, which swell when exposed to heat, forming an insulating char layer on top of the virgin coating. Although the temperature curves related to so-called cellulosic fires are often referred to as slow heating curves, special cases where the protective char is mechanically damaged and partly removed can cause extremely fast heating of the coating. This situation, for a solvent based intumescent coating, is simulated using direct insertion of free films into a muffle oven. The char formed is evaluated with respect to the mechanical resistance against compression, degree of expansion, and residual mass fraction. Experimental results show that when using this type of shock heating, the mechanical resistance of the char against compression cannot meaningfully be correlated to the expansion factor. In addition, char properties, measured at room temperature, were dependent on the preceding storage conditions (in air or in a desiccator). The char was found to have the highest mechanical strength against compression in the outer crust facing the heat source. For thin (147 μm) free coating films, a tendency to contract in the horizontal plane was observed. The experimental approach is relevant for testing of intumescent coatings used in buildings where moving or falling objects may damage the char during a fire.     

A hybrid intumescent fire retardant coating from cake- and eggshell-type IFRC

In this study the applicability of flame retardant mixed with a carbon source (such as pentaerythritol) for the intumescent fire retardant coating (IFRC) daubed on the top of a piece of plywood was investigated. There are three kinds of flame retardants used in this study: (1) artificial mesophase graphite powder (MGP), (2) sericite (Al₄(OH)₄(KAlSi₃O₁₀)₂), and (3) graphite. The desirable sizes of graphite, MGP and sericite were obtained by sieving. The graphite, MGP and sericite were characterized using a scanning electron microscope (SEM) and an energy dispersive spectrum (EDS). The IFRC, which consisted of 19.8% of flame retardant (or flame retardant mixed with carbon source), 15% of dehydrate agent, 18% of foaming agent, 7.2% of resin binder, and 40% of solvent, was prepared and daubed on the top of plywood. The fire protection capability of IFRC was tested using a flammability 45° tester. A conventional IFRC (with the carbon source) was also prepared to study the effect of adding the mixture of flame retardant and carbon source on the fire protection capability of IFRC. The microstructures of the conventional IFRC, the IFRC with flame retardant, and the hybrid IFRC (with flame retardant and carbon source) were inferred and demonstrated using SEM micrographs of the cross-section of three kinds of burnt IFRC. Most interestingly, the fire protection capability of the hybrid IFRC exceeds that of the conventional IFRC even though the percentage of carbon in the burnt hybrid IFRC is less than that in the burnt conventional IFRC.     

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。     

Effect of boron compounds on fire protection properties of epoxy based intumescent coating

The aim of this study was to investigate the effect of boron compounds on fire protection properties of intumescent coating based on ammonium polyphosphate (APP). Three kinds of boron compounds namely boric acid (BA), zinc borate (ZB) and melamine borate (MB) were used. Total amount of flame retardant additive was kept constant at 30 wt%, and boron compounds were used at three concentrations of 1, 3 and 5 wt%. Thermogravimetric analysis (TGA), Attenuated total reflectance–Fourier transform infrared spectroscopy (ATR‐FTIR) and fire test were conducted for the determining the fire performance of intumescent coating. According to fire test results, BA and MB showed synergistic effect at 1 wt% loading. ZB showed antagonistic effect at all concentrations. Fire protection effect of intumescent coating decreased as the added amount of boron compound increased regardless of boron compound type because of suppression of intumescence. Copyright © 2016 John Wiley & Sons, Ltd.     

High strength retention and dimensional stability of silicone/alumina composite panel under fire

Compact silicone/alumina composite was obtained by highly filling aluminum oxides and hydroxides in silicone resin. The flexural strength and dimensional change of the silicone/alumina composite after being fired has have been studied. It presented a special fire resistance, which could well coordinate the contradiction between the mechanical strength retention and the dimensional stability of silicone‐based composite in case of catching fire. Thermogravimetric analysis, scanning electron microscopy, X‐ray diffraction, transmission electron microscopy, and electron dispersion spectroscopy were applied to systematically explore the process of the in‐suit organic‐to‐inorganic transformation. A possible mechanism was proposed to illustrate the phenomenon of the high strength retention and dimensional stability of silicone/alumina composite under fire. Copyright © 2011 John Wiley & Sons, Ltd.     

有机硅绝热涂料的研制

用RTV585硅橡胶、填料及固化剂60R制成了绝热涂料；考察了填料种类及用量对绝热涂料绝热性能、力学性能和粘接性能的影响及金属表面处理方式对金属与涂料的粘接性能的影响。结果表明，当RTV585用量为100g、固化剂60R用量为2g、软木粉用量为20g时，可制得绝热性能良好的涂料；采用喷砂 清洗 偶联剂的表面处理模式，可大大提高涂料与金属的粘接性能。     

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     

阻燃陶瓷化硅橡胶的制备与性能

以硅橡胶为基质,通过添加玻璃粉和阻燃剂制备了兼具阻燃和耐火性能的陶瓷化硅橡胶材料,研究了阻燃剂氢氧化镁、氢氧化铝和硼酸锌对硅橡胶瓷化性能的影响,并通过扫描电子显微镜观察了瓷化物的断面形貌。结果表明,纯硅橡胶以及只添加玻璃粉的硅橡胶不具备足够的阻燃性,需要用少量阻燃剂替代部分玻璃粉。3种阻燃剂中硼酸锌的添加使硅橡胶具备了最佳的阻燃性,试样的极限氧指数达到48,垂直燃烧等级达到FV-0;氢氧化镁的添加使硅橡胶的陶瓷化效果更加明显,瓷化物的密度、吸水率和弯曲强度可分别达到1.633 4 g/cm3、9.86%和6.43 MPa。     

陶瓷化耐火硅橡胶的应用进展

概述了陶瓷化耐火硅橡胶在电线、电缆中的应用研究。     

Study on mechanical properties and fire resistance of porous ceramic silicone rubber

Porous ceramic silicone rubber (PCSR) has an excellent ablative resistance because of its strong carbon layer structure after burning. However, as a marine sealant material, it also needs to have better mechanical properties for better application. In this study, PCSR composites were prepared by compounding with different additives and different viscosity base adhesives, and their fire resistance, tensile properties, and bond strength of multiple substrates at different temperatures were investigated and compared. When the ratio of 20,000 to 80,000 viscosity matrix adhesive is 3:7, the material prepared by adding deketoxime crosslinker and silane coupling agent containing amino and epoxy groups together can reach more than 1.4 MPa tensile shear strength at 150°C. Sintering experiments have shown that PCSR composites can still maintain the strength and integrity of the carbon layer structure, and the results of the A-60 standard fire resistance test for cable and pipe penetration devices have shown that marine PCSR sealants can effectively prevent flame propagation.     

脲基含氢硅树脂对室温硫化硅橡胶耐热性能的影响

以六甲基二硅氧烷、四甲基二硅氧烷、正硅酸乙酯、γ-脲丙基三甲氧基硅烷为主要原料合成脲基含氢硅树脂(UHMQ),并将其加入到乙烯基硅橡胶中作为耐热助剂,考察了UHMQ用量对室温硫化硅橡胶耐热性能及力学性能的影响。结果表明,当UHMQ的用量为8份时,硅橡胶复合材料的初始分解温度最高可达414.79℃。当UHMQ的用量为6份和8份时,在200,300,400℃下热空气老化24 h硅橡胶复合材料的质量损失率明显下降,且热空气老化24 h后仍保持一定弹性。UHMQ的加入可提高硅橡胶复合材料的力学性能,当UHMQ的用量为6份时,硅橡胶复合材料的剪切强度达到最大值。     

Improvement of the adhesion of silicone to aluminum using plasma polymerization

The adhesion-in-peel test was used to determine peel strength and adhesion characteristics of a cured-in-place silicone elastomeric joint sealant on aluminum substrates. The sealant used was a Dow Corning Type 3145 RTV Adhesive Sealant. The results showed that the silicone sealant had poor adhesive bonding to the untreated aluminum. Plasma polymerization of hexamethyldisiloxane (HMDS) onto the aluminum was seen to move the locus of adhesive failure to being between the plasma film and the silicone. Plasma polymerization of HMDS with oxygen carrier gas produced excellent adhesion and cohesive failure in the silicone was observed.     

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.     

The dynamic flammability and toxicity of magnesium hydroxide filled intumescent fire retardant polypropylene

The flammability properties of an intumescent fire retardant polypropylene added with magnesium hydroxide was discussed in this study. To evaluate the flammability of the material, limit oxygen index, smoke emission, tensile strength, and our exploitation dynamic flammability evaluation system, tests were assessed in experiments. The results showed that the intumescent flame retardant ammonium polyphosphate-filled polypropylene has superior flammability properties but higher carbon oxide (CO) concentration and smoke density. By adding some magnesium hydroxide additives in intumescent fire retarded polypropylene, the smoke density and CO concentration decrease; and the compound also has superior fire properties. It is concluded that intumescent system and magnesium hydroxide additives are effective on improving combustion properties for polypropylene. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:989–995, 1998     

Smoke suppression properties of epoxy crosslinked structure and intumescent fire retardant in epoxy‐based intumescent fire‐retardant coating

In this article, the smoke production behaviors of crosslinked epoxy/polyamide resin (EP/PA) and intumescent fire retardant (IFR) in epoxy‐based intumescent fire‐retardant coating (IFR‐EP) have been investigated using cone calorimeter, smoke density instrument, and thermogravimetric analysis and Fourier transform infrared spectroscopic measurement. The static and dynamic smoke production behaviors of EP/PA and IFR‐EP indicate that the IFR has an excellent smoke suppression effect on EP/PA by forming protective char layer in the late combustion stage, while the epoxy crosslinked structure in IFR‐EP can enhance the thermal stability and reduce smoke production in the early combustion stage. In addition, according to the discussion of pyrolysis gas products, the IFR can effectively suppress the production of toxic and inflammable gases during the combustion process. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43912.     

钢材构件专用隔热防火涂料(非膨胀型)的研制

以改性有机硅树脂为漆基，加入隔热性能优良的颜填料、化学反应型复合阻燃剂、隔热防火剂和高效固化剂N-7或N-9，配制成CT系列室温固化钢结构高层建筑钢材构件专用隔热防火涂料；该涂料可长期耐450℃高温，过火时间大于3h(900℃明火)。     

偶联剂B对RTV硅橡胶粘接强度的影响

为了提高RTV硅橡胶与金属材料的粘接强度 ,对金属材料表面采用偶联剂处理 ,筛选了多种偶联剂 ,进行了稳定性和加速老化试验 ,测试了试件的剪切强度和扯离强度 ,结果表明偶联剂B具有较佳的性能 ,不仅能够提高粘接强度 ,而且粘接强度稳定     

The piloted transition to flaming in smoldering fire retarded and non‐fire retarded polyurethane foam

The piloted transition from smoldering to flaming, though a significant fire safety concern, has not been previously extensively studied. Experimental results are presented on the piloted transition from smoldering to flaming in non‐fire retarded (NFR) polyurethane foam and the fire retarded polyurethane foam Pyrell^®. The samples are small blocks, vertically placed in the wall of an upward wind tunnel. The free surface is exposed to an oxidizer flow and a radiant heat flux. The smolder product gases pass upwards through a pilot. The experiments on NFR foam show that the smolder velocity and peak smolder temperature, which increase with the oxygen concentration and heat flux, are strongly correlated to the transition to flaming event, in that there are minimum values of these parameters for transition to occur. The existence of a minimum smolder velocity for ignition supports the concept of a gaseous mixture reaching a lean flammability limit as the criterion for the transition to flaming. To compensate for the solid‐ and gas‐phase effects of the fire retardants on the piloted transition in Pyrell, it was necessary to increase the oxygen concentration and the power supplied to the smolder igniter and the pilot. The piloted transition is observed in oxygen concentrations above 17% in NFR foam and above 23% in Pyrell. The results show that although Pyrell is less flammable than NFR foam, it is still susceptible to smoldering and the piloted transition to flaming in oxygen‐enriched environments, which is of interest for special applications such as future space missions. Copyright © 2008 John Wiley & Sons, Ltd.