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     

The effects of intumescent flame retardant including ammonium polyphosphate/pentaerythritol and fly ash fillers on the physicomechanical properties of rigid polyurethane foams

In this study, rigid polyurethane foams that contain up to 5.0 wt % fly ash (FA) being a by‐product of thermal power stations and being cheap source were successfully produced using a polyurethane injection machine. The effects of FA content on the thermal conductivity, compressive strength, and flammability were investigated. The morphology of the cell was observed under a special microscope. The incorporation of FA in rigid polyurethane foams may dramatically decrease production costs and reduce environmental pollution. In addition, the effects of intumescent flame retardant composed of ammonium polyphosphate and pentaerythritol were examined in pure rigid polyurethane foams and FA‐rigid polyurethane foams. It was found that 5.0 and 7.5 wt % intumescent flame retardant loadings enhanced the thermal stability and improved the flammability resistance of the foams. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Ignition,combustion, toxicity,and fire retardancy of polyurethane foams: A comprehensive review

This review provides insight into the ignition, combustion, smoke, toxicity, and fire‐retardant performance of flexible and rigid polyurethane foams. This review also covers various additive and reactive fire‐retardant approaches adopted to render polyurethane foams fire‐retardant. Literature sources are mostly technical publications, patents, and books published since 1961. It has been found by different workers that polyurethane foams are easily ignitable and highly flammable, support combustion, and burn quite rapidly. They are therefore required to be fire‐retardant for different applications. Polyurethane foams during combustion produce a large quantity of vision‐obscuring smoke. The toxicity of the combustion products is much higher than that of many other manmade polymers because of the high concentrations of hydrogen cyanide and carbon monoxide. Polyurethane foams have been rendered fire‐retardant by the incorporation of phosphorus‐containing compounds, halogen‐containing compounds, nitrogen‐containing additives, silicone‐containing products, and miscellaneous organic and inorganic additives. Some heat‐resistant groups such as carbodiimide‐, isocyanurate‐, and nitrogen‐containing heterocycles formed with polyurethane foams also render urethane foams fire‐retardant. Fire‐retardant additives reduce the flammability, smoke level, and toxicity of polyurethane foams with some degradation in other characteristics. It can be concluded that despite many significant attempts, no commercial solution to the fire retardancy of polyurethane foams without some loss of physical and mechanical properties is available. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

水性聚氨酯膨胀型阻燃涂料的研究进展

水性聚氨酯涂料若未经阻燃处理,存在引发火灾的隐患,因此水性聚氨酯的阻燃研究是水性聚氨酯功能化的重要方向之一。介绍了水性聚氨酯阻燃涂料的分类,按不同分类标准可分为共混复配型和反应型,膨胀型和非膨胀型。对水性聚氨酯阻燃涂料阻燃效应和阻燃机理进行了探讨,并重点介绍水性聚氨酯膨胀型阻燃涂料的研究现状。最后提出了现在水性聚氨酯膨胀型阻燃涂料存在的问题,并对水性聚氨酯膨胀型阻燃涂料的发展趋势进行了展望。     

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     

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.     

Properties of polyurethane coatings containing additives of phenolic compounds

The properties of polyurethane containing five kinds of model phenolic additives were investigated. The IR spectra of polyurethane containing phenolic additives indicated that the phenolic additives reacted with isocyanate groups in a polyisocyanate compound. For an index of anticorrosion, the tensile adhesion strength was measured for polyurethane coatings with phenolic additives on steel plates treated with the salt‐water spraying test for 3000 h. It was found that there was a relationship between the tensile adhesion strength of polyurethane and the density. We considered the reason to be that the increase in density (i.e., a reduction in free volume) should provide a route to reduce salt‐water access to an adhesive bond. The increase in density was explained by the term antiplasticizers, which means that the phenolic additives reduce the free volume that is available for molecular motion in the stiff chain of polyurethane. In the polyurethanes with every phenolic additive, the elongation was increased, the moduli were decreased, the storage modulus was decreased, and the coefficient of thermal expansion was increased. These phenomena are the characteristics of plasticizers. Thus, the phenolic additives have both the character of antiplasticizers and plasticizers, but the polyurethane with phenolic additives had more characteristics of plasticizers than those of antiplasticizers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2099–2106, 2006     

Development of an epoxy based intumescent system comprising of nanoclays blended with appropriate formulating agents

A novel intumescent coating technology for metallic surfaces was developed using functionalized clays, which were intercalated and exfoliated into nanodimensions. The nanoclays were formulated in epoxy resins and blended with appropriate additives to design intumescent coatings for metallic surfaces. With the high dispersion of nanoclay the flame retardancy is improved. The extent and the homogeneity of the exfoliation and dispersion of the clay particles were assessed employing small-amplitude oscillatory shear. The performance and properties of the coatings were evaluated by means of fire resistance testing, thermo-gravimetric analysis and mechanical properties. The incorporation of the nanoclays significantly increased the elasticity and the viscosity of the intumescent formulations and improved the fire resistance of the epoxy coatings. It is observed that significant gains in flame retarding properties could be achieved when the clay platelets could be adequately exfoliated and dispersed.     

Preparation and characterization of new flame retardant polyurethane composite and nanocomposite

In this work, a new flame retardant additive [2‐phenyl‐1,3,2 oxazaphospholidine 2‐oxide (POPO)] containing phosphorus and nitrogen is synthesized using phenyl phosphonic dichloride, ethanol amine, and copper (II) chloride, as catalyst. POPO is characterized by ¹H‐NMR, ¹³C‐NMR, and ³¹P‐NMR and used as additive in polyurethane composites. Moreover, two commercial flame retardant additives [tricalcium diphosphate and hexabromocyclododecane (HBCD)] as well as nanoclay are used to compare flame retardancy of the synthesized additive. Limited oxygen index (LOI) and time burning (flammability test) of polyurethane composites and nanocomposites are evaluated. The results of the LOI test demonstrate that POPO is an excellent flame retardant additive and can be used to improve flame retardancy of polyurethane composites. In addition, increasing the additive content leads to an improvement of the flame retardancy of the samples. The LOI results show, however, that POPO is a good flame retardant, but the high synthesis cost of this flame retardant is a major disadvantage. Thermogravimetric analysis results show that using POPO in polyurethane matrices leads to low thermal stability and high char residue. Moreover, the nanocomposite has better thermal stability than the other samples. Scanning electron microscope micrographs have been used to evaluate the char residue of the samples. These micrographs indicate that POPO is an intumescent flame retardant and HBCD follows a nonintumescent mechanism. Exfoliated/intercalated structures have been shown for nanocomposites by transmission electron microscope. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

膨胀型阻燃剂阻燃PP/SBS/POE共混物的性能研究

研究了聚磷酸胺类膨胀型阻燃剂（AP）和磷酸酯膨胀型阻燃剂(NP)的用量对聚丙烯（PP）/苯乙烯-丁二烯-苯乙烯共聚物（SBS）/乙烯-辛烯共聚物（POE）共混体系的力学性能、燃烧性能和遇水抗析出性能的影响。探讨了阻燃剂的析出机理,并从耐电压方面分析其在电线电缆领域应用的可行性。结果表明,NP具有更高的分解温度和残炭率。将AP与NP分别加入到PP/SBS/POE共混体系中,共混物的拉伸强度和断裂伸长率都降低,但阻燃性能提高。在相同添加量下,NP阻燃的共混物的拉伸强度和氧指数更高,而AP更能促进共混物成炭。AP和NP在热水浸泡过程中都会析出,析出过程是由表层向内部逐步析出的过程,析出量随着浸泡时间延长而增加。在相同的浸泡时间下,NP体系的析出量更小。浸泡后的共混物的力学性能和阻燃性能下降。     

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.     

高弹性水性聚氨酯橡胶涂料的研制

以水性丙烯酸改性聚氨酯(PUA)乳液为基料,加入功能性颜填料和助剂,制备出一种高弹性水性聚氨酯橡胶涂料。对高弹性水性聚氨酯涂料与传统橡胶涂料进行了一系列模拟涂覆橡胶管的对比试验,结果表明:高弹性水性聚氨酯涂料可以很好地满足工艺要求。     

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.     

Layer double hydroxide and sodium montmorillonite multilayer coatings for the flammability reduction of flexible polyurethane foams

Flexible polyurethane foam (PUF) is coated by layer‐by‐layer (LbL) assembly using branched polyethyleneimine (BPEI), poly(acrylic acid) (PAA), and two different charged nanoparticles, such as sodium montmorillonite (Na‐MMT) and layered double hydroxide (LDH). Three different deposition strategies, that is, bilayer, trilayer, and quadlayer, exhibit different coating growth, morphology, and flammability properties. Changing the nanosheet from LDH to MMT dramatically alter the coating mass for the same number of layers. A five bilayer PAA/BPEI+LDH coating reduced the peak heat release rate by 40% and the average heat release rate by 70%, which is two times more effective than commercial fire retardants (FRs) and other LbL‐FR coatings for PUF. MMT and LDH mixed multilayers resulted in effective flame‐retardant coatings with less coating mass by manipulating the deposition strategy. This study manifests the flexibility of LbL to fine‐tune flammability reduction by switching the coating weight gains, which is significant to accelerate the development of other LbL coating regardless of the intended applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41767.     

Effects of liquid‐type silane additives and organoclay on the morphology and thermal conductivity of rigid polyisocyanurate‐polyurethane foams

This article investigates the effects of liquid‐type silane additives and organoclay as a solid‐type additive on the morphological, mechanical and thermal insulating properties of polyisocyanurate‐polyurethane (PIR‐PUR) foams. The organoclay likely acted as nucleating agents during the formation of PIR‐PUR foams. When the liquid silane additives and organoclay were added, the cell size and thermal conductivity of the PIR‐PUR foams appeared to be decreased. However, organoclay did not contribute to reduce the cell size distribution of the foam. PIR‐PUR foams synthesized with tetramethylsilane as a liquid‐type additive showed a smaller average cell size and lower thermal conductivity than that of PIR‐PUR foams synthesized with the other silane additives or with organoclay as a solid‐type additive. For the PIR‐PUR foam with organoclay/TEMS (1.5/1.5 php) mixture, cell size and thermal conductivity of the foam showed similar to the foam with TEMS. These results suggest that smaller cell size appears to be one of the major factors in the improvement of thermal insulation properties of the PIR‐PUR foams. Silane additives did not seem to have a strong effect on the flammability of the PIR‐PUR foams. However, heat resistance was more dominant for the foam with the organoclay at the higher temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Formation and investigation of epoxy intumescent compositions modified by active additives

Results are reported of research on intumescent composites based on epoxy resin cross‐linked with polyethylene polyamine and containing ammonium polyphosphate and such modifying additives as calcium borate, manganese dioxide, nickel, and chromium, containing tubulenes as gas‐formers and carbonization stimulators. The changes in composition and physicochemical properties of modified compositions under conditions of heat and fire were investigated by X‐ray photo‐electron spectroscopy, atomic force microscopy, and local force spectroscopy. Ammonium polyphosphate mainly stimulates carbonization processes on the inner surface of a bubble being formed during foam coke formation. The introduction of metal‐containing tubulenes leads to the formation of fire‐retardant and low flammability‐compositions with high coke and carbon structures content. The use of calcium borate in the compositions considerably increases the strength of foam coke being formed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1477–1483, 2002     

Development of value-added polyethylene grades with extended service lifetime: Weathering resistant flame retarded materials for outdoor applications

The current article deals with the development of different novel, tailor-made polyolefin formulations exhibiting both low flammability and high weathering resistance, so as to provide value-added polyethylene grades with extended service lifetime. Two low-density (LDPE) and one linear low-density (LLDPE) polyethylene grades were modified via melt compounding with an additive system comprising: (a) a nitrogen-phosphorous intumescent system for flame retardance and (b) a hindered amine light stabilizer and a benzophenone-type UV absorber for UV/heat stabilization, at a total loading of 30–35 wt%. The target was to reach V0 classification in UL94V flammability tests, while to a large extent maintaining the mechanical properties, such as, tensile and impact strength of the investigated polymers, thus ensuring that the additives do not interfere significantly with the material quality. Subsequently, the compounds were subjected to separate artificial UV and heat aging at 100°C for 1500 h; the formulations showed good flame retardance, even after prolonged artificial weathering, but there was an observable, although acceptable, decrease in the mechanical properties. Nevertheless, all the results show that the developed polyethylene compounds are very promising for outdoor applications, such as, irrigation piping and profiles, where long-term weathering stability is important, and where flame retardance is important for safety during storage.     

Intrinsic flame resistance of polyurethane flexible foams: Unexpectedly low flammability without any flame retardant

Virgin polyurethane flexible foams are widely assumed to be highly flammable materials. The flammability of three model polyurethane flexible foams suggests that this may not be universally true. Two of them show unexpectedly low flammability in the limiting oxygen index test and pass flammability tests such as FMVSS 302 and FAR 25.853. Cone calorimetric measurements at 25 kW/m² and 50 kW/m² furthermore show a high resistance against ignition and demonstrate the self‐extinguishing properties of these two virgin, flame‐retardant‐free, polyurethane flexible foams.     

低表面能UV固化水性柔感塑料涂料的研究

将季戊四醇三丙烯酸酯（PETA）和聚二甲基硅氧烷（PDMS）引入水性聚氨酯的主链,制得硅氧烷改性的UV固化水性聚氨酯乳液,通过FTIR红外光谱对乳液的结构进行表征。将该乳液与助剂复配,制得水性塑料涂料,并对涂层的固化动力学和表面性能进行研究。与未改性的涂料相比,硅氧烷改性的UV固化水性涂料具有良好的耐水性和耐溶剂性,同时保留了优良的手感,可用作水性柔感塑料涂料。