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.     

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.     

Application of cone calorimeter for the assessment of class of flame retardants for polypropylene

The study presented addresses the fire behaviour of polypropylene compounded with six classes of flame retardants. The application of cone calorimetry for the assessment of the thermal characteristics of the tested materials and their comparison with thermogravimetry are the central point of this research. This study only presents data for 25 kW/m² of incident heat flux exposure and includes five tests for polypropylene with no additives and five tests for polypropylene with flame retardants based on triglycidylisocyanurate and lignin. The data collected include the rate of heat release, mass loss rate, char yield, time to ignition and time of total combustion. Results represent meaningful comparison between the behaviour of the materials under simulated fire conditions, using the cone calorimeter, and in the slow dynamic environment utilized in thermogravimetric analysis. © 1998 John Wiley & Sons Ltd.     

Effects of variations in incident heat flux when using cone calorimeter test data for prediction of full‐scale heat release rates of polyurethane foam

The development of methods to predict full‐scale fire behaviour using small‐scale test data is of great interest to the fire community. This study evaluated the ability of one model, originally developed during the European Combustion Behaviour of Upholstered Furniture (CBUF) project, to predict heat release rates. Polyurethane foam specimens were tested in the furniture calorimeter using both centre and edge ignition locations. Input data were obtained using cone calorimeter tests and infrared video‐based flame area measurements. Two particular issues were investigated: how variations in incident heat flux in cone calorimeter tests impact heat release rate predictions, and the ability of the model to predict results for different foam thicknesses. Heat release rate predictions showed good agreement with experimental results, particularly during the growth phase of the fire. The model was more successful in predicting results for edge ignition tests than for centre ignition tests and in predicting results for thinner foams. Results indicated that because of sensitivity of the burning behaviour to foam specimen geometry and ignition location, a single incident heat flux could not be specified for generating input for the CBUF model. Potential methods to determine appropriate cone calorimeter input for various geometries and ignition locations are discussed. Copyright © 2014 John Wiley & Sons, Ltd.     

Effect of Melting Behaviour on Upward Flame Spread of Thermoplastics

The effect of melting behaviour on upward flame spread of thermoplastic materials when subjected to small ignition sources and considered to suffer no external flux was studied using large-scale tests. For moderate fire conditions the cone calorimeter was utilized, with the sample set in a vertical orientation to study the melting behaviour of the specimens. Under these conditions the results indicate that the melting behaviour significantly affects upward flame spread behaviour. A pool of the melt which formed at the base of the vertically oriented sample tested creates a pool fire which then controls the fire growth and flame spread. In contrast, it was found that some thermoplastic materials which have higher glass transition temperatures or undergo a special pyrolysis process such as depolymerization, intumescing or charring do not experience significant melting behaviour when exposed to the same thermal insult. As a result, they behave very differently in terms of upward flame spread. The study also indicates that the melting behaviour of thermoplastic materials is an important characteristic in fires which should be taken into account in the development of modelling, in particular for upward flame spread models. © 1997 by John Wiley & Sons, Ltd.     

Ignition performance of new and used motor vehicle upholstery fabrics

This paper examines the standards for fire safety in transport systems and in particular the test method for the flammability of materials within passenger compartments of motor vehicles. The paper compares data from ignition tests conducted in the cone calorimeter and the FIST apparatus with tests conducted using the FMVSS 302 horizontal flame spread apparatus. Ten materials were selected as representative of those used as seat coverings of private and commercial passenger vehicles. The time to ignition of new and used materials subject to exposure heat fluxes between 20 kW/m² and 40 kW/m² was measured. The results from the ignition tests were analysed using thermally thick and thermally thin theoretical models. The critical heat flux for sustained piloted ignition was determined from the time to ignition data using the thermally thin approach. Derived ignition temperatures from both the thermally thick and thermally thin methods were compared with measurements using a thermocouple attached to the back surface of materials in selected tests. The flame spread rates in the FMVSS 302 apparatus were determined and a comparison was made between the performance of the materials in the flame spread apparatus, the cone calorimeter and the FIST. The results suggests that a critical heat flux criterion could be used to provide an equivalent pass/fail performance requirement to that specified by the horizontal flame spread test although further testing is needed to support this. Copyright © 2004 John Wiley & Sons, Ltd.     

ZnS as fire retardant in plasticised PVC

The flame retardant effect of zinc sulphide (ZnS) in plasticised poly(vinyl chloride) (PVC‐P) materials was investigated. PVC‐P containing different combinations of additives such as 5% ZnS, 5% of antimony oxide (Sb₂O₃) and 5% of mixtures based on Sb₂O₃ and ZnS were compared. The thermal degradation and the combustion behaviour were studied using thermogravimetry (TG), coupled with FTIR (TG–FTIR) or with mass spectroscopy (TG–MS), and a cone calorimeter, respectively. A detailed and unambiguous understanding of the decomposition and release of the pyrolysis products was obtained using both TG–MS and TG–FTIR. The influence of ZnS, Sb₂O₃ and the corresponding mixtures on the thermal decomposition of PVC‐P was demonstrated. Synergism was observed for the combination of the two additives. The combustion behaviour (time to ignition, heat release, smoke production, mass loss, CO production) was monitored versus external heat fluxes between 30 and 75 kW m^?2 with the cone calorimeter. Adding 5% of ZnS has no significant influence on the fire behaviour of PVC‐P materials beyond a dilution effect, whereas Sb₂O₃ works as an effective fire retardant. Synergism of ZnS and Sb₂O₃ allows the possibility of replacing half of Sb₂O₃ by ZnS to reach equivalent fire retardancy. © 2002 Society of Chemical Industry     

The rapid mass calorimeter: A route to high throughput fire testing

The rapid mass calorimeter based on reduced‐size specimens is proposed for accelerated fire testing and put up for discussion, particularly for flame retarded polymeric materials. A mass loss calorimeter is combined with a semiautomatic sample changer. Experiments on specimens of reduced size were conducted on poly(methyl methacrylate), poly(propylene), polyamide 66, poly(ether ether ketone), and pine sapwood square samples with edge lengths of 100, 75, 50, 25, 20, and 10 mm. Specimens of 20 × 20 mm² were selected to achieve a crucial reduction in specimen size and a measuring protocol developed. A total of 71 different polymeric materials were investigated in the rapid mass calorimeter and cone calorimeter for comparison and several materials with different heat release rate characteristics in the pyrolysis combustion flow calorimeter to test this additional screening method as well. The important fire properties obtained in the rapid mass calorimeter show reasonable correlation with the cone calorimeter results but also with the oxygen index. All in all, the rapid mass calorimeter produces reliable and meaningful results and, despite acceleration and size reduction, still allows for a certain degree of burning behavior interpretation. Material savings of 96% and time savings of around 60%‐70% are achieved compared to measure cone calorimeter.     

Investigation of a combustible material in the fire of Hengyang merchant's building

Agaric, a kind of important combustible material in the fire of Hengyang merchant's building, was investigated using different experiment equipments. Its degradation and pyrolysis behavior were studied by means of thermogravimetric and kinetic analysis and pyrolysis gas chromatography–mass spectroscopy analysis. External radiation heat and internal heat were used to ignite the agaric. For external radiation ignition, a series of bench‐scale fire tests were done in cone calorimeter in accordance with ISO 5660. As for the internal heat ignition, a fire test was carried out in a full‐scale room in accordance with ISO 9705. Multi‐parameter measurement, including heat release rate (HRR), mass loss rate (MLR), temperature field and species concentration, has been accomplished. Meanwhile, the process of a full‐scale fire test was numerically simulated. The computational results were consistent with experiment data, which will lay down a good foundation for further study in fire reconstruction of the whole fire. Copyright © 2008 John Wiley & Sons, Ltd.     

Comparison of cone and OSU calorimetric techniques to assess the flammability behaviour of fabrics used for aircraft interiors

Two test methods for measuring the heat release rate, HRR have been compared on fabric composites used for aircraft interior materials as side‐wall panels. These methods are based on the principles of direct measurement of the convective and radiant heat by thermopiles using an Ohio State University (OSU) calorimeter, and oxygen consumption using a cone calorimeter. It has been observed when tested by standard procedures, cone results at 35 kW/m² incident heat flux do not correlate with OSU results at the same heat flux. This is because in the cone calorimeter, the sample is mounted horizontally whereas the OSU calorimetric method requires vertical sampling with exposure to a vertical radiant panel. A further difference between the two techniques is the ignition source—in the cone it is spark ignition, whereas in the OSU it is flame ignition; hence, samples in the OSU calorimeter ignite more easily compared to those in the cone under the same incident heat fluxes. However, in this paper we demonstrate that cone calorimetric exposure at 50 kW/m² heat flux gives similar peak heat release results as the 35 kW/m² heat flux of OSU calorimeter, but significantly different average and total heat release values over a 2 min period. The performance differences associated with these two techniques are also discussed. Moreover, the effects of structure, i.e. type of fibres used in warp/weft direction and design of fabric are also analysed with respect to heat release behaviour and their correlation discussed. Copyright © 2005 John Wiley & Sons, Ltd.     

Fire retardancy of polypropylene/flax blends

A comprehensive characterization of the thermal and the fire behaviour is presented for polypropylene (PP) flax compounds containing ammonium polyphosphate (APP) and expandable graphite as fire retardants. Thermogravimetry coupled with an evolved gas analysis (TG-FTIR) was performed to ensure a significant thermal analysis. The fire response under forced flaming conditions was studied using a cone calorimeter. The external heat flux was varied between 30 and 70 kW m⁻² so that the results could be evaluated for different fire scenarios and tests. Different flammability tests (UL 94, limiting oxygen index, glow wire test, GMI 60261) were performed and the results compared with the cone calorimeter data. The different char forming mechanisms are described and the resulting fire retardancy is classified. The successful and ecological friendly fire retardancy is a technological breakthrough for PP/flax biocomposites.     

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.     

Investigation of polymeric materials using the cone calorimeter

The use of polymeric materials in building or construction applications is steadily increasing. Therefore, the potential for these materials to be exposed to fire is also increased. The understanding of the pyrolysis characteristics of these materials is thus a necessity. There are many standard tests used to evaluate materials. Unfortunately, the correlation between these tests and large scale fire is less than desirable. A new bench scale rate of heat release apparatus, the Cone Calorimeter, is now being used more frequently in pyrolysis testing of polymeric materials. This apparatus has been shown to correlate much better between room scale testing and large scale fire testing. The cone Calorimeter provides a pyrolysis profile of a material under ambient oxygen conditions. Characteristics such as ignition time, total heat release, maximum rate of heat release, mass loss during pyrolysis, CO₂, CO, and smoke production are determined. In this work several almost neat polymers are examined and the general pyrolysis characteristics of these polymers are discussed. The objective of this work is to provide information of basic polymeric pyrolysis properties of these materials. Variations in the material, i.e., molecular weight, polydispersity, and residual catalysis, along with changes in testing procedures, can have dramatic effects on results. Obviously the addition of flame retardant and flame retardant packages to any of these materials will have dramatic effects on results.     

Heat release and classification of fire retardant wood products

A comparison is presented of cone calorimeter heat release data between fire retardant treated and untreated wood products. The test results show significant differences between these two groups. The parameters included in the comparison are time to ignition, rate of heat release (peak and average values) and total heat release. The wood-based products were also tested in different small-scale national standard fire tests and in the full-scale room fire test. Fire retardant wood products achieve an improved classification both in present national systems and in possible new systems based on the cone calorimeter and the room fire test.     

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.     

Enhancement of fire retardancy properties of glass fibre–reinforced polyesters composites

This paper presents the results of an experimental investigation on the fire retardancy properties of glass fibre–reinforced polyester (GFRP) composites with bisphenol‐A vinylester and isophthalic polyester as matrices and low electrical conductivity E‐glass fibres as reinforcement. The fire protection systems tested were alumina trihydrate (ATH), decabromodiphenyl ether (DBDE), and antimony trioxide (Sb₂O₃). A mass loss cone calorimeter was used to obtain the properties of heat release rate (HRR), peak HRR, total heat released, total mass loss, time to ignition, and time of combustion. Moreover, limiting oxygen index (LOI), UL‐94, and glow‐wire tests were also performed. The fire tests were carried out in order to investigate if the combination of ATH and DBDE could have “additive,” “antagonistic,” or “synergistic” effects on the flame retardant properties of the GFRP studied in this work. In addition, the influence of the ATH content variation on flame retardant properties was also evaluated. The results indicate that the sole addition of ATH at 47.7 phr could lead to the complete inhibition of the composites ignition, while the materials containing DBDE exhibit ignition and flame propagation in the cone calorimeter test.     

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.     

A study on fire behaviour of combustible components of two commonly used photovoltaic panels

Photovoltaic (PV) modules are installed in some modern buildings for generating renewable energy. When a building catches fire, burning PV panels can contribute to an already very hazardous environment. Two common polycrystalline silicon PV samples A and B were selected with their chemical composition analysed by the Fourier transform infrared spectroscopy with justification by X‐ray photoelectron spectroscopy results. Sample A was confirmed to be a silicate product with polyurethane adhesive, and sample B has epoxy resin and is likely to have flame retardant as claimed. Thermal analysis by heating the samples was carried out using thermogravimetric analysis and thermogravimetric analysis coupled with infrared spectroscopy. The fire behaviour was then studied by a cone calorimeter under radiative heat fluxes from 10 to 70 kWm^?2. Three key parameters representing flashover propensity, total heat release per unit area and smoke toxicity hazard were obtained from the cone calorimeter tests for ranking the thermal and smoke hazards. The thermal hazards of both PV samples are low, at least during the early stage of a fire without flame acting directly on the sample. However, vast quantities of smoke were emitted from burning PV panels under high heat fluxes. Copyright © 2016 John Wiley & Sons, Ltd.     

Thermal properties of polyethylene flame retarded with expandable graphite and intumescent fire retardant additives

Low‐density polyethylene was flame retarded by combinations of expandable graphite with either ethylenediamine phosphate or 3,5‐diaminobenzoic acid phosphate. Cone calorimeter, laser pyrolysis, and open flame exposure tests (supported by video and infrared camera data capture and analysis) were conducted to assess ignition and burn behavior. Cone calorimeter results indicated substantial reductions in the peak heat release rates for all flame‐retarded samples but with reduced ignition times and increased flame out times. Smoke generation was suppressed in the presence of expandable graphite. Infrared and video data from open flame fire tests indicated cohesive bonding of expanded strings and thermal shielding properties in all binary systems. All binary systems delivered fire retardation exceeding any of the single fire retardant compounds. They were also able to withstand higher temperatures before ignition, burn through, or sag occurred. All ethylenediamine phosphate‐containing binary systems prevented sample burn through, maintaining structural integrity of samples until eventual melting of the polymer media occurred. Thermogravimetric analysis laser pyrolysis results confirmed the good thermal shielding imparted by the intumescent additives. Copyright © 2016 John Wiley & Sons, Ltd.     

Evaluation of thermal fire hazard of 10 polymeric building materials and proposing a classification method based on cone calorimeter results

The use of polymeric building materials has been grown in many countries of Middle East in recent years. However, there are only a few fire testing laboratories in this region. Therefore, development of a method for controlling the reaction to fire of materials with bench scale tests is necessary. Providing a framework for classification of thermal fire hazard of materials based on bench scale heat release rate results was attempted. The fire behavior of 10 polymeric building materials was tested with cone calorimeter. The relationship between reaction to fire variables and physical properties of tested samples was examined. The thermal fire hazards of materials were assessed using methods presented by different researchers and with Conetools software. The results revealed that time to ignition, peak rate of heat release, and total heat release are essential variables for determining the fire hazard of materials. A classification method is proposed, which can be used in building codes in countries where the full‐scale test facilities are not available. The method also can be used for quality control purpose and evaluation of fire behavior of materials in bench scale by manufacturers. An example of potential requirements for interior finishes for some occupancy types is also presented. Copyright © 2013 John Wiley & Sons, Ltd.