Fire-hazard assessment of extended-chain polyethylene and aramid composites by cone calorimetry

A cone calorimeter is used to determine the fire performance of polymer composite materials containing combustible reinforcing fibres in addition to combustible matrix resins. Extended-chain polyethylene and aramid fibre-reinforced composites containing epoxy, vinylester and phenolic matrix resins are examined at various cone irradiances. Values for time to ignition, rate of heat release, effective heat of combustion, smoke density and evolved carbon monoxide and carbon dioxide are reported for the reinforcements, matrix resins and composites. The reinforcements have a significant effect on the fire-hazard properties of the composite materials. For the epoxy and vinylester composites, times to ignition reflect those of the component of higher ignitability. This was not the case for the aramid-reinforced phenolic composite, in which the resin surface layer hinders combustion of the fabric reinforcement. Resin and reinforcement contributions to the composite rate of heat release behaviour as a function of time are generally discernible.     

原竹纤维增强酚醛泡沫材料的燃烧特性

采用锥形量热仪研究了不同原竹纤维加入量对酚醛泡沫材料的燃烧性能和烟气释放特性的影响。结果表明,酚醛泡沫材料的引燃时间随着原竹纤维加入量的增大而缩短,热释放速率、总放热量、质量损失速率、生烟速率和总发烟量随原竹纤维加入量的增大而总体呈增大趋势,但由于酚醛泡沫材料具有良好的阻燃性能,其燃烧快速成炭特性阻碍了热量在材料内层传递,减缓了原竹纤维在0~480 s燃烧阶段的热释放和烟气释放,使得加入量为1.5 %~3.5 %的原竹纤维作为其增强材料时,对酚醛泡沫材料的阻燃性能影响较小;而原竹纤维的加入量≥5.0 %时,对酚醛泡沫材料的阻燃性能有较大的降低作用,必须进行阻燃改性。     

Flammability of GRP for use in ship superstructures

The burning characteristics of glass-reinforced panels with an isophthalic polyester resin, the same resin with an inorganic flame retardant, two differing vinylester resins or a resole phenolic as the matrix were tested at a range of incident heat flux values using a cone calorimeter. The phenolic composite was superior at all levels showing a longer ignition time, reduced heat output, less contribution to a low-level sustained fire (25 kWm^?2) and lower smoke yield.     

Cone calorimetry—a review of tests carried out on plastics for the association of plastic manufacturers in Europe

An evaluation of the cone calorimeter by the Association of Plastic Manufacturers in Europe (APME) involved testing of 25 plastic materials together with two natural polymers. Specimen preparation is identified as having an important influence on the results, especially for certain types of material. Ignition time, rate of heat release (RHR) and smoke results are presented to show the influence of external heat flux. The dynamic smoke results (which should be measured from the time of exposure) are only relevant to well-ventilated fires unless the cone calorimeter is specially modified. For a complete evaluation a cumulative smoke measurement may be needed in addition. Although the cone calorimeter is a valuable research tool, and may be used frequently in industry, it needs to be made more robust and user friendly to avoid excessive downtime and to reduce calibration time. If the instrument is to be used for routine development and quality assurance, only one or two heat flux levels should be selected. These could represent a developing and a developed fire and should depend on the product application.     

Flammability studies of thermally resistant polymers using cone calorimetry

The effectiveness of a set of thermally resistant polymers was evaluated for aircraft applications using the cone calorimeter (ASTM E1354/ISO 5660) under heat fluxes simulating real scale fires. This study included eight developmental and commercial thermally resistant polymers available in the literature and/or marketplace. The polymers included were aromatic polyester, polyetherimide, fluorine‐containing polyetherketone, phosphorus and fluorine‐containing co‐polyetherketone, fluorine and phosphorus‐containing polyether, fluorine‐containing polyester, poly(dimethylsiloxane)etherimide and polysulfone. The effects of fluorine, phosphorus, silicon and sulfone group in polymers were examined. This evaluation was based on time to ignition, peak, average and total heat release rates obtained at an external heat flux of 50 kW/m². Other parameters such as effective heat of combustion, mass loss and rate of smoke and toxic gas evolution were collected during the cone calorimeter test. Copyright © 2000 John Wiley & Sons Ltd.     

硅烷交联聚乙烯无卤阻燃材料燃烧性能的研究

采用极限氧指数、锥形量热计和热分析等手段，研究了氢氧化镁(MH)和其他类型的无卤阻燃剂在硅烷交联聚乙烯(SXPE)体系中的阻燃协效作用。氧指数实验结果表明，硅烷交联的聚乙烯／氢氧化镁(SXPE／MH)体系的氧指数高于未交联的PE／MH体系的氧指数，若在SXPE／MH阻燃体系中添加适量的其他无卤阻燃剂，如磷氮类化合物(NP-28)和氮类化合物[三聚氰胺氰尿酸盐(MCA)]氧指数都有提高。锥形量热计实验结果表明，在SXPE／MH阻燃体系中添加适量的NP一28或MCA，体系的着火时间有所延长，热释放速率和发烟量也有不同程度的降低。热分析实验结果显示，NP-28或MCA对SXPE／MH体系的热分解特性有一定的影响。     

用锥形量热仪研究阻燃聚丙烯的燃烧行为

采用锥形量热仪比较了溴系阻燃聚丙烯、无卤阻燃聚丙烯的燃烧行为。结果表明:按UL94标准测试V-0阻燃等级的阻燃聚丙烯复合材料,采用无卤阻燃体系比采用溴系阻燃体系具有更低的热释放速率、烟生成速率和总烟释放量。     

Comparison of three test methods for measuring rate of heat release

Three test methods for measuring the rate of heat release, RHR, have been compared on the same building materials. The test methods are the OSU-box modified for O₂-consumption, the STFI open arrangement and the NBS cone calorimeter. All methods are based on the oxygen-consumption technique. Radiation intensities up to 50 k Wm^?2 have been applied. Thirteen different materials were tested. The results obtained using the three methods seem to be quite similar in spite of the different equipment used. The minor deviations observed in the results seem to be systematic and may be due to the different testing arrangements. There is a good correlation between results, e.g. total heat release up to 1min after ignition, obtained by the different methods. Additional information about the time to ignition is obtained simultaneously. Heat-release rates in the vertical and horizontal orientations are also compared in the NBS cone calorimeter.     

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.     

氢氧化镁与有机膨润土协同阻燃EVA的研究

通过熔融共混法制备了乙烯-乙酸乙酯共聚物(EVA)／膨润土纳米复合材料,采用垂直燃烧仪、锥形量热仪和热重分析等手段,研究了氢氧化镁和膨润土对无卤阻燃EVA的协同阻燃效应。结果表明,与EVA／氢氧化镁混合物相比,EVA／膨润土／氢氧化镁体系的阻燃性能明显提高,熔体滴落明显降低,火焰强度明显降低,点燃时间大幅度延长,热氧稳定性显著提高。EVA／膨润土／氢氧化镁(100／3／147,质量份数)体系具有较好的阻燃性能,垂直燃烧性能达到UL-94V-0级,最高热释放速率降低到142．4kW／m2,点燃时间延长到145s。     

Controlled-atmosphere cone calorimeter studies of silicones

A controlled-atmosphere cone calorimeter was used to investigate the burning of a silicone fluid and two silicone elastomers. The silicone materials were tested at 50 kW/m² incident heat flux in environments containing 15–30% oxygen. The test results were compared with a high molecular weight hydrocarbon fluid and an ethylene propylene rubber in terms of time to ignition, peak heat release rate and total heat released, carbon monoxide yield and carbon monoxide production rate, and smoke production and smoke production rate. The data from this study show that when materials burn in oxygen-enriched, normal, and vitiated atmospheres, silicone-based materials have a comparatively low peak heat release rate, total heat released, average CO production rate, and average smoke production rate as compared with organic-based materials. The smoke production and smoke production rate of silicone elastomers can be significantly reduced by adding appropriate smoke suppressants and additives. © 1997 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.     

Influences of specimen size and heating mode on the ignitability of polymeric materials in typical small‐scale fire test conditions

Small‐scale fire tests including the Underwriters Laboratories 94 (UL94) vertical burning test and the cone calorimeter test are widely used. In this paper, the ignition times of materials heated by the conical heater of a cone calorimeter and the UL94 flame were measured. It was found that for polymer bars heated by the UL94 flame, the ignition time is relatively short and increases with the specimen thickness. But the contribution of the specimen thickness to the delay of the ignition time is limited. The intrinsic properties of materials play a more important role in the ignition time than the specimen thickness. In addition, respectively corresponding to one‐dimensional, two‐dimensional, and three‐dimensional heat transfer, three heating modes of the UL94 flame were presented and compared with the conical heater. It was found that whether the heat source is the conical heater or the UL94 flame, the ignition time depends on the heat flux and the multidimensional heat transfer. The ignition time decreases with the increasing heat flux, and the magnitude order of the ignition time might drop when the heating mode changes from one‐dimensional to multidimensional heat transfer. Copyright © 2011 John Wiley & Sons, Ltd.     

利用锥形量热仪研究聚氨酯硬泡的燃烧性能

利用锥形量热仪对硬质聚氨酯泡沫(RP UF)的燃烧特性进行了研究.通过对RP UF燃烧过程中的热释放速率、热释放总量、烟生成速率和总产烟量等进行系统性测试,讨论了聚醚多元醇、聚酯多元醇以及异氰酸酯指数(R值)对RP UF热危险性和烟气危险性的影响.结果表明,聚酯多元醇替代聚醚多元醇制备的RP UF燃烧过程中的热释放速率...     

Fire-resistant aluminosilicate composites

The fire response of a potassium aluminosilicate (Geopolymer) matrix carbon fiber composite was measured and the results compared to organic matrix composites being used for transportation, military, and infrastructure applications. At irradiance levels of 50 kWm⁻² typical of the heat flux in a well-developed fire, glass- or carbon-reinforced polyester, vinylester, epoxy, bismaleimde, cyanate ester, polyimide, phenolic, and engineering thermoplastic laminates ignited readily and released appreciable heat and smoke, while carbon-fiber reinforced Geopolymer composites did not ignite, burn, or release any smoke even after extended heat flux exposure. The Geopolymer matrix carbon fiber composite retains 67% of its original flexural strength after a simulated large fire exposure. © 1997 US Government     

PP/APP/磷系阻燃剂FR复合材料的燃烧性能研究

将新型磷系阻燃剂1,3,5-三(5,5-二甲基-1,3-二氧杂环己内磷酸基)苯(FR)、无规聚丙烯(APP)加入聚丙烯(PP)中制备了 PP/APP/FR 复合材料,采用极限氧指数测定、垂直燃烧实验(UL94)、锥形量热分析对复合材料燃烧性能进行了研究。结果表明,APP/FR 提高了 PP 复合材料的氧指数和垂直燃烧性能级别,延长了点燃时间,降低了热释放速率和燃烧烟气中的 CO、CO_2浓度,阻燃效果显著。当15%(质量分数,下同)FR 和10%APP 复配阻燃 PP 时,复合材料的氧指数达29.6%,UL94 V-0级。     

Thermal degradation of epoxy resin/carbon fiber composites: Influence of carbon fiber fraction on the fire reaction properties and on the gaseous species release

The thermal degradation of epoxy resin/carbon fiber composites has been performed in ISO 5660 standard cone calorimeter using a piloted ignition. Two kinds of composites that differ by their volume fractions in carbon fiber (56 and 59 vol.%) were tested in this study. The cone calorimeter irradiance level was increased up to 75 kW m^?2 to characterize the carbon fiber volume fraction influence on the composite thermal degradation. Thus, main flammability and combustibility parameters were determined and calculated such as mass loss, mass loss rate, ignition time, thermal response parameter, ignition temperature, thermal inertia, and heat of gasification. As a result, all the characteristic parameters for the thermal resistance of composites were decreased when the carbon fiber volume fraction increased. Moreover, the main gaseous products (such as NO, CO, CO₂, HCN, H₂O, and lightweight hydrocarbons) emitted as well as the oxygen consumption during the composite thermal decomposition were also quantified simultaneously with a portable gas analyzer and a Fourier transform infrared spectrometer. The main species emission yields calculated from the gas analysis results increased slightly when the carbon fiber volume fraction was increased in the initial sample. The epoxy composite was represented as a sooty material with a significant production of soot particles during the combustion process. Furthermore, heat release rate, total heat release, and effective heat of combustion were calculated by using the oxygen consumption calorimetry technique. The results obtained showed that a small increasing of composite carbon fiber amount induced a sharp decrease of heat release rate and total heat release. Copyright © 2014 John Wiley & Sons, Ltd.     

Flammability testing of flame-retarded epoxy composites and phenolic composites

Flame-retarded epoxy composites and phenolic composites containing fiberglass, aramid (Kevlar® 49), and graphite fiber-reinforcements were tested using the NASA upward flame propagation test, the controlled-atmosphere cone calorimeter test, and the liquid oxygen (LOX) mechanical impact test. The upward flame propagation test showed that phenolic/graphite had the highest flame resistance and epoxy/graphite had the lowest flame resistance. The controlled-atmosphere cone calorimeter was used to investigate the effect of oxygen concentration and fiber reinforcement on the burning behavior of composites. The LOX mechanical impact test showed that epoxy/fiberglass had the lowest ignition resistance and phenolic/aramid had the highest ignition resistance in LOX. The composites containing epoxy resin and/or aramid fiber reinforcement reacted very violently in LOX upon mechanical impact. © 1997 by John Wiley & Sons, Ltd.     

Combustion behaviour of fabric and polyurethane flexible foam mock-up combinations under Cone Calorimetry test conditions

The relative contributions of fabric and foam on important fire hazard parameters as measured in the cone calorimeter were determined for various mock-up combinations. Three commercial types of high-resilience PU flexible slabstock foams, representing a wide range of combustion performance, were combined with three different fabrics: polyester, polypropylene and combustion-modified cotton. Total heat release of the combinations correspond well with the value calculated from the individual components and is determined by the density and effective heat of combustion of the components, and the foam/fabric weight ratio. The foams show a smaller variation in effective heat of combustion than the fabrics. Covering of PU flexible foams with a fabric results in general in a delay of ignition and peak rate of heat release. Performance of the mock-ups is mainly determined by the fabric but is also influenced by the quality of the foam.     

Fire safety of thermoplastic polyurethane based on pyromellitic dianhydride

In this paper, pyromellitic dianhydride (PMDA) was firstly used as fire safety agent for thermoplastic polyurethane (TPU). And, the fire safety improvement of PMDA in TPU was intensively investigated by limiting oxygen index (LOI), smoke density test (SDT), cone calorimeter test, and thermogravimetric/infrared spectroscopy, respectively. It has been found that PMDA could significantly improve the ignition level, and the LOI value increase to 28.5% when 8.0 wt% PMDA was incorporated into TPU; PMDA also could effectively suppress the smoke production and heat release during the combustion process. The peak heat release rate and total smoke release of the sample with 8.0 wt% PMDA were decreased by 68% and 22% compared with pure TPU in cone calorimeter test. The thermogravimetric/infrared spectroscopy results showed that PMDA could improve the thermal stability of TPU composites at high temperature and increased the release of CO₂, H₂O, and so on. All results confirmed that PMDA would have a good prospect in reducing the fire hazard of TPU.