Assessing the reaction to fire of cables by a new bench‐scale method

The recently approved EU Construction Products Regulation (CPR) applies to cables as construction products. The difficulty of predicting the fire performance of cables with respect to propagation of flame and contribution to fire hazards is well known. The new standard EN 50399 describes a full‐scale test method for the classification of vertically mounted bunched cables according to CPR. Consideration of the material, time, and thus cost requires an alternative bench‐scale fire test, which finds strong demand for screening and development purposes. The development of such a bench‐scale fire test to assess the fire performance of multiple vertically mounted cables is described. A practical module for the cone calorimeter is proposed, simulating the fire scenario of the EN 50399 on the bench scale. The efficacy of this module in predicting full‐scale CPR test results is shown for a set of 20 different optical cables. Key properties such as peak heat release rate (PHRR), fire growth rate (FIGRA), and flame spread are linked to each other by factors of around 5. In a case study, the bench‐scale test designed was used to investigate the influence of the main components on the fire behaviour of a complex optical cable. Copyright © 2016 John Wiley & Sons, Ltd.     

The calculation of the heat release rate by oxygen consumption in a controlled‐atmosphere cone calorimeter

The standard cone calorimeter according to ASTM E 1354 and ISO 5660 enables reaction‐to‐fire tests to be performed in ambient atmospheric conditions. A controlled‐atmosphere chamber modifies the standard apparatus in a way that allows tests to be performed in nonambient conditions as well. The enclosed chamber is placed underneath the standard exhaust hood and does not have a closed connection to the hood. With this open arrangement, the exhaust gases are diluted by excess air drawn in from the laboratory surroundings. Heat‐induced changes in the consequential dilution ratio affect the calculation of fire quantities and, when neglected, lead to deviations of up to 30% in heat release rate. The paper introduces a test protocol and equations to calculate the heat release rate taking dilution effects into account. A mathematical correction is shown that compensates for the dilution effects while avoiding extensive mechanical changes in the equipment. Copyright © 2013 John Wiley & Sons, Ltd.     

Characterization of highly under‐ventilated fires using the cone calorimeter

The cone calorimeter, originally designed with an ‘open configuration‘, may be used in combination with a closed‐combustion chamber in order to test specimens in oxygen‐depleted atmospheres (air vitiation effect) or in fuel‐rich combustion (ventilation effect). However, highly under‐ventilated conditions are not achievable, as a consequence of an overconsumption of oxygen due to the incomplete confinement of the flame and imperfections in the air tightness of the combustion volume. In this work, these issues were solved by lowering the combustion zone, in order to fit a 600 mm chimney on the top of the controlled‐atmosphere chamber, and further improving the sealing of the whole setup. n‐Heptane was used as a reference fuel, and its combustion properties were determined in under‐ventilated conditions. The yields of main combustion species correlated well with the global equivalence ratio, for values of Φ up to three. The use of a Fourier‐transform infrared spectrometer allowed further refinement of the total unburned‐fraction composition. The relative concentration of species like methane, ethylene, or acetylene was shown to be relatively constant over the range of under‐ventilated conditions. Copyright © 2015 John Wiley & Sons, Ltd.     

The effect of processing routes on the thermal and mechanical properties of poly(urethane‐isocyanurate) nanocomposites

A systematic investigation of four processing routes was implemented so as to evaluate the thermal and mechanical properties of nanosilica (NS) reinforced poly(urethane‐isocyanurate) nanocomposites (NC). The NS dispersion in the Polmix and the Isomix routes was performed in the polyol and the isocyanate precursor, respectively. The Isopol and the Solvmix routes consisted on the dispersion of the filler after the mixing of the precursors and with the aid of solvents, respectively. The NS dispersion, fractography (SEM, TEM), flexural and tensile mechanical properties, thermogravimetric analysis and FTIR analysis of NCs was performed as a function of processing route, isocyanate index, and NS concentration. Each route produced a NC with distinct properties, which were correlated to the NS agglomeration degree and how the NS affected the thermal transitions of the HS and the relative ratio of urethane and isocyanurate chemical groups. For example, the NC prepared with the Polmix route had substantial improvements of σ_t and ε_t of around +40 and +52%, respectively and an improved thermal resistance of the Hard Segments. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42750.     

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.     

Fire performance of brominated and halogen‐free flame retardants in glass‐fiber reinforced poly(butylene terephthalate)

This paper investigates the effects of brominated and halogen‐free fire retardants on the fire performance of glass‐fiber (GF) reinforced poly(butylene terephthalate) (PBT). Brominated polystyrene was used as the brominated fire retardant, whereas aluminum diethylphosphinate with/without nanoclay as halogen‐free fire retardants (HFFRs). Tests were conducted by using thermogravimetric analysis, limiting oxygen index (LOI), UL94, and the cone calorimeter. Thermogravimetric analysis results show that decomposition of GF plus PBT (PBT + GF) starts earlier in the presence of all fire retardants (FRs). In the cone calorimeter, all FRs reduce significantly the heat release rate (HRR) compared with PBT + GF, with brominated polystyrene achieving lowest HRR primarily because bromine released in the pyrolysis gases inhibits combustion. Brominate polystyrene does not, however, affect the mass loss rate. Aluminum diethylphosphinate alone has significant effects on reduction of both HRR and mass loss rate, which become considerably more when combined with nanoclay. It was also found that the combustion efficiency of the brominated polystyrene compound is much lower than that of HFFRs, indicating that brominated polystyrene has higher gas phase flame retardant efficiency compared with HFFRs because the bromine radicals released during degradation of brominated polystyrene effectively quench the chemical reactions of the pyrolysis gases due to degradation of PBT.     

Combustion and fire retardance of poly(2,6-dimethyl–1,4-phenylene ether)–high-impact polystyrene blends. II. Chemical aspects

The chemical reactions occurring during the intumescent process taking place in the combustion of the poly(2,6-dimethyl–1,4-phenylene ether)–high-impact polystyrene blends (PPE–HIPS) are studied in detail through the chemical characterization of the burnt and original material by infrared, pyrolysis–gas chromatography–mass spectrometry, and direct insertion probe spectrometry. Evidence is given of thermal rearrangement in the blend of the polyether PPE chains to polybenzylic structures occurring in the heating conditions of pyrolysis or combustion, as previously shown, to take place in thermal degradation of PPE. The rearranged chain segments are shown to give a larger contribution to the intumescent char, while volatile blowing products are mostly formed by polystyrene and polybutadiene components. From PPE–HIPS blends, the volatilization of the fire-retardant triphenyl phosphate (TPP), which when heated alone volatilizes at a temperature below that of PPE–HIPS degradation, is delayed probably by hydrogen bonding with PPE. This allows TPP to play the typical flame inhibition role of volatile phosphorus compounds. Moreover, it is found that TPP favors the PPE rearrangement and henceforth increases the char yield of the burning blend, which is a typical condensed phase fire-retardant action. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:2231–2240, 1998     

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.     

Prediction of fire classification for wood based products. A multivariate statistical approach based on the cone calorimeter

Wood has long traditions as a building material, and is often used in construction elements, and as interior and exterior surfaces in the Nordic countries. In most applications, there are reaction to fire requirements to products used as surfaces, e.g. in escape routes and larger public spaces. Most wood products will therefore have to be treated with fire retardant (FR) agents to fulfil the strict requirements to properties connected to heat release and flame spread. Unfortunately, FR agents usually also increase the smoke production, as they cause a more incomplete combustion of the wood. The wood product manufacturers seek to find the optimal amount of FR additives where both heat release and smoke production in the classifying test are within the requirements given in the building regulations. This paper describes models for prediction of the European reaction to fire classes of wood products. The models are based on multivariate statistical analysis, and use test results from the cone calorimeter test as input. The presented models are, with very good precision, able to predict which Euroclass and additional smoke class a wood based product would obtain if it were to be tested in the single burning item test. Copyright © 2006 John Wiley & Sons, Ltd.     

High‐resolution thermogravimetry of poly(phenylene sulfide) film under four atmospheres

The thermal degradation of poly(phenylene sulfide) (PPS) film is investigated in air, nitrogen, helium, and argon with different physical and reactive characteristics at room temperature to 790°C as ascertained by high‐resolution thermogravimetry (TG) at a variable heating rate in response to the changes in the sample's weight‐loss rate. Only a one‐step degradation process of the PPS is observed in nitrogen and argon, but a two‐step degradation process of PPS is found in helium. A four‐step degradation process of the PPS, which is hardly ever revealed by traditional TG, is found in this investigation, especially in air. The initial thermal degradation temperature and temperature at the first maximum weight‐loss rate of the PPS increase in the following order: helium < nitrogen < argon < air. The first maximum weight‐loss rate also increases with the variation of the atmosphere in the order nitrogen < air < argon < helium. The char yield at 700°C increases in the order air < helium < nitrogen < argon. The activation energy of the major degradation process of PPS, as calculated based on the high‐resolution TG data, is very high and increases in the order nitrogen < argon < helium < air. The thermal decomposition parameters of the PPS determined by the high‐resolution TG are systematically compared with those by traditional TG at a constant heating rate. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1940–1946, 2002     

Multi‐scale experimental investigations of the thermal degradation of pine needles

In this work, the thermal degradation of pine needles (from a Mediterranean species) was studied using a thermogravimetric analysis and cone calorimeter that were coupled to Fourier transform infrared spectrometer. The thermogravimetric analyses were carried out at four heating rates, in both air and nitrogen atmospheres. The evolution of gaseous components, mass loss and mass loss rate were recorded as a function of time and temperature. In order to account for the observed behaviours of the materials, we have also proposed a mechanism for the thermal degradation of pine needles, by primarily analysing the evolutions of both mass loss rate and gaseous components under nitrogen and air atmospheres. The kinetic parameters were subsequently estimated by using a genetic algorithm method. The cone calorimetric measurements were mainly conducted with a view to investigating the influence of thermal transfer processes, occurring in a porous bed of pine needles with regard to its thermal degradation. The experiments were conducted at five external heat fluxes under a well‐ventilated atmosphere. Measurements consisted of the mass loss, mass loss rate and the amount of gaseous emissions. The main gases emitted during the thermal degradation and the combustion of the pine needles were found to be CH₄, CO, CO₂, NO and water vapour. In addition, the evolution of the temperature was measured by using a set of five thermocouples, placed in a vertical position at the centreline of the sample. The results obtained showed that the bed of pine needles behaved as a thermally thick fuel. On the contrary, at higher external heat fluxes, the sample behaved as a thermally thin sample. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis,characteristic of a novel flame retardant containing phosphorus and its application in poly(ethylene‐co‐vinyl acetate)

A novel flame retardant (SPDH) containing phosphorus was synthesized through the reaction of 10‐(2, 5‐dihydroxyphenyl)‐9, 10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO‐HQ) and synthesized intermediate product 3, 9‐dichloro‐2, 4, 8, 10‐tetraoxa‐3, 9‐diphosphaspiro(5.5)undecane‐3, 9‐dioxide (SPDPC). The structure and properties of SPDPC and SPDH were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) spectroscopy and thermogravimetric analysis (TGA). After blending with poly(ethylene‐co‐vinyl acetate) (EVA), the flame‐retardant properties of EVA/SPDH composites were estimated by cone calorimeter, limited oxygen index (LOI) and UL‐94 tests, whereas the thermal stabilities were investigated using TGA. The morphological microstructure of the char formed by EVA/SPDH composite after combustion in cone calorimeter was investigated by scanning electron microscopy (SEM). The results indicate that the flame retardant and thermal stability were improved by incorporation of SPDH. The rich foamy char layers were observed from the residues after combustion in a cone calorimeter, which exactly benefits the improvement of thermal stability and flame retardant property of materials. Copyright © 2010 John Wiley & Sons, Ltd.     

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.     

A study on thermal behavior of a poly(VDF‐CTFE) copolymers binder for high energy materials

This article describes a study on thermal behavior of poly(vinylidene fluoride‐chlorotrifluoroetheylene) [poly(VDF‐CTFE)] copolymers as polymeric binders of specific interest for high energy materials (HEMs) composites by thermal analytical techniques. The non‐isothermal thermogravimetry (TG) for poly (VDF‐CTFE) copolymers was recorded in air and N₂ atmospheres. The results of TG thermograms show that poly(VDF‐CTFE) copolymers get degrade at lower temperature when in air than in N₂ atmosphere. In the derivative curve, there was single maximum degradation peak (T_max) indicating one‐stage degradation of poly(VDF‐CTFE) copolymers for all the samples. The other thermal properties such as glass transition temperature (T_g) and degradation temperature (T_d) for poly(VDF‐CTFE) copolymers were measured by employing differential scanning calorimeter (DSC) technique. The kinetic parameters related to thermal degradation of poly(VDF‐CTFE) copolymers were investigated through non‐isothermal Kissinger kinetic method using DSC method. The activation energies for thermal degradation of poly(VDF‐CTFE) copolymers were found in a range of 218–278 kJ/mol. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effects of NCO/OH ratio and catalyst concentration on structure,thermal stability,and crosslink density of poly(urethane‐isocyanurate)

Poly(urethane‐isocyanurate)s were synthesized by reacting toluene diisocyanate and poly(propylene glycol) with various stochiometric ratios (1–3) in the presence of different concentrations of dibutyltin dilaurate (DBTDL) and ferric acetylacetonate (FeAA). The influence of the NCO/OH ratio and the catalyst type and concentration on the extent of urethane and isocyanurate formation were examined using Fourier transform IR spectroscopy. No trimer formation was observed in the presence of the FeAA catalyst. The percentage of the trimer group and the trimer/urethane content were found to be increased with increasing the stochiometric ratio or DBTDL concentration. The thermal decomposition of the copolyurethanes in an inert atmosphere was studied by means of thermogravimetry (TG). The TG curves showed three decomposition steps with the principal degradation temperature at about 355–385°C. The effects of the NCO/OH ratio, catalyst type and concentration, and heating rate on the thermal stability of the copolyurethanes were determined. The Flynn–Wall, Kissinger, and Ozawa methods were used to calculate the activation energies of thermal decomposition. The swelling behavior of solid copolyurethanes in toluene showed that, as the DBTDL concentration and/or NCO/OH ratio increased, the swelling ratio and average molecular weight between crosslinks were decreased whereas the crosslink density was increased. The sol fraction of solid copolyurethanes was examined and found to be reduced when the percentage of DBTDL or the stochiometric ratio was raised. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 963–972, 2003     

The effect of the trimerization catalyst on the thermal stability and the fire performance of the polyisocyanurate‐polyurethane foam

In this work, 3 currently used trimerization catalysts, TMR‐2 (quaternary ammonium), K‐15 (potassium octoate), and PU‐1792 (potassium acetate) were used to produce rigid polyisocyanurate (PIR) foams with certain amounts of isocyanurate contents. The results from Fourier transform infrared (FTIR) quantitative analysis showed that PU‐1792 had the highest catalytic efficiency in isocyanurate formation. Then, the effect of different amounts of PU‐1792 catalyst on isocyanurate ring output was further investigated, and the result showed that the highest amount of isocyanurate ring formation could be attained by the 5 pphp of PU‐1792 catalyst. It was also found that the increased amount of isocyanurate ring could result in reduced cell size, improved compressive strength, and lowered thermal conductivity of PIR foam. The results from thermogravimetric analysis (TGA) and cone calorimeter (CONE) test revealed that the thermal stability and fire performance of PIR foam could be improved with the increased amount of isocyanurate ring. Furthermore, the CONE test indicated that the smoke production of PIR foam decreased approximately 51.7% in comparison to the reference polyurethane (PU) foam, and the SEM image of char morphology showed that the char of PIR foam was more compact than PU foam.     

Synthesis and characterization of poly(urethane‐ester)s based on calcium salt of mono(hydroxybutyl)phthalate

Calcium‐containing poly(urethane‐ester)s (PUEs) were prepared by reacting diisocyanate (HMDI or TDI) with a mixture of calcium salt of mono(hydroxybutyl)phthalate [Ca(HBP)₂] and hydroxyl‐terminated poly(1,4‐butylene glutarate) [HTPBG₁₀₀₀], using di‐n‐butyltin‐dilaurate as catalyst. About six calcium‐containing PUEs having different composition were synthesized by taking the mole ratio of Ca(HBP)₂:HTPBG₁₀₀₀:diisocyanate (HMDI or TDI) as 3:1:4, 2:2:4, and 1:3:4. Two blank PUEs were synthesized by the reaction of HTPBG₁₀₀₀ with diisocyanate (HMDI or TDI). The polymers were characterized by IR, ¹H NMR, Solid state ¹³C‐CP‐MAS NMR, TGA, DSC, XRD, solubility, and viscosity studies. The T_g value of PUEs increases with increase in the calcium content and decreases with increase in soft segment content. The viscosity of the calcium‐containing PUEs increases with increase in the soft segment content and decreases with increase in the calcium content. X‐ray diffraction patterns of the polymers show that the HMDI‐based polymers are partially crystalline and TDI‐based polymers are amorphous in nature. The dynamic mechanical analysis of the calcium‐containing PUEs based on HMDI shows that with increase in the calcium content of polymer, modulus (g′ and g″) increases at any given temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1720–1727, 2006