Specific Extinction Area Research Articles

Effect of copper chelate of pyridineanilide modified montmorillonite on the flammability and thermal stability of polypropylene

Polypropylene (PP) compositions with montmorillonite (MMT) modified with either pyridineanilide (PyA) or its copper chelate (CuPyA) were the subjects of our study. The effects of PyA/MMT and CuPyA/MMT on the following properties of PP compositions were studied using cone calorimetry: time to ignition (TTI), combustion time, heat release rate (HRR), heat of combustion, CO and CO2 evolution and specific smoke extinction area (SEA). It has been found that the composition PyA/MMT:PP (5:95, MH2) showed the best flame retardant properties. Thermal stability of the compositions investigated has been determined by thermogravimetric analysis. Introduction of PyA/MMT as well as of CuPyA/MMT significantly improves thermal stability of PP, although what concerns an increase in onset temperature slightly better effect has been observed in case of the samples containing copper.

A study of γ‐radiation‐crosslinked HDPE/EPDM composites as flame retardants

AbstractThe dynamic flammability of flame‐retardant composites that consist of high‐density polyethylene (HDPE) and ethylene–propylene–diene rubber (EPDM) and other additives, and can be used as wire‐ and cable‐insulation materials, was studied before and after irradiation. The data for the heat‐release rate (HRR), the time to ignition, the specific extinction area and the concentrations of CO and CO2 from the burning process of cone colorimeter tests were assessed. By blending HDPE with EPDM, the HRR of HDPE was reduced and the residue char of the composite increased. The HRR of HDPE/EPDM was further reduced and the residue char of HDPE/EPDM was further increased after irradiation. The oxygen index, mechanical properties, and thermal stability of the composites, and the morphology of the char formed in the cone calorimeter test, were also investigated. Copyright © 2004 Society of Chemical Industry

Flammability characterization and synergistic effects of expandable graphite with magnesium hydroxide in halogen-free flame-retardant EVA blends

The flammability characterization and synergistic effects of different types of expandable graphite (EG) with magnesium hydroxide (MH) in halogen-free flame-retardant (HFFR) ethylene vinyl acetate (EVA) blends have been studied by cone calorimeter test (CCT), thermogravimetric analysis (TGA), limiting oxygen index (LOI), and UL-94 test. The results show that the particle size and expansion ratio of EG have a great effect on the flammability of the HFFR EVA/MH/EG blends. The EG with bigger particle size and higher expansion ratio can apparently increase the LOI value and improve the UL-94 flammability properties of EVA blends. The data obtained from the CCT indicate that the heat release rate (HRR), the effective heat of combustion (EHC), and the mass loss rate (MLR) of EVA/MH/EG blends decrease remarkably with increasing the particle size and expansion ratio of EG. However, the specific extinction area (SEA) data show that the addition of EG can apparently increase the smoke emission of EVA/MH/EG blends. The TGA results show that the thermal stability of EVA/MH/EG blends increase with increasing the EG particle size and expansion ratio.

Cone calorimetric study of copper-promoted smoke suppression and fire retardance of poly(vinyl chloride)

Copper-based smoke suppression additives for poly(vinyl chloride) (PVC) were tested for crosslinking capability in pyrolysis studies and for smoke suppression and fire retardance by the use of cone calorimetry. Crosslinking of PVC at 190 °C was promoted by most of the additives without an obvious dependence on additive copper content or copper oxidation state. The copper additives (at 10 parts by weight per hundred parts of resin) proved to inhibit both smoke and heat evolution in burning PVC samples (both rigid and plasticized) in cone calorimetric studies. Mixed-metal oxides of copper were especially effective in this regard. Synergism in smoke suppression was noted for combinations of Cu 3(MoO 4) 2(OH) 2 and CuSnO 3 in plasticized PVC. A 2:1 (w/w) mixture of Cu 3(MoO 4) 2(OH) 2 and CuSnO 3 yielded a reduction in specific extinction area (a measure of smoke obscuration) of 64% and a reduction in total smoke release of 79% vs. the control sample.

Combustion behaviour and thermal properties of UV cured methacrylated phosphate/epoxy acrylate blends

Methacrylated phosphates (MAPs) were blended in certain ratios with a commercial epoxy acrylate to obtain UV curable flame retardant resins. The flame retardancy and thermal properties of their UV cured films were investigated by the combustion behaviour, limiting oxygen index (LOI), thermal degradation and glass transition temperature ( T g). The results showed that the peak and average heat release rates decreased to the approximate levels of pure MAPs when 17 wt.% of MAPs was added, and no obvious effects were observed from the films with higher loading levels. The LOI increased along with the content of MAPs, and the total heat release, contrarily, decreased. The total smoke production was suppressed by MAPs addition as it leads to an effective decrease of mass loss, although MAPs have no effect on the specific extinction area. The T g decreased with increasing content of MAPs due to the reduction in rigidity of the polymer chains, and the lower cross-link density of the cured film.

PIPD, a new high‐modulus and high‐strength polymer fibre with exceptional fire protection properties

AbstractThe development of the new high‐modulus and high‐strength fibre M5, made of poly{2,6‐diimidazo[4,5‐b:4′,5′‐e]‐pyridinylene‐1,4(2,5‐dihydroxy)phenylene} or PIPD, has resulted in an organic polymer fibre with exceptional fire protection properties when compared with PBO, Twaron, Kevlar and Nomex fibres. The PIPD as‐spun fibre with a modulus of 150 GPa and a tensile strength of 2.5 GPa is a crystal hydrate containing 21 wt% water. Cone calorimeter measurements yielded a fire performance index (FPI) 20 times higher than Nomex, with extremely low value for the specific extinction area (SEA) characterizing the smoke formation. The PIPD‐HT fibre (recrystallized in an after treatment into the anhydrous crystalline structure) with a modulus >300 GPa and a strength >5 GPa has a FPI value similar to PBO but shows much less smoke formation than this fibre. Copyright © 2002 John Wiley & Sons, Ltd.

Combustion characteristics of halogen‐free flame‐retarded polyethylene containing magnesium hydroxide and some synergists

AbstractHalogen‐free flame‐retarded polyethylene materials have been prepared by using magnesium hydroxide (MH) as a flame retardant combined with red phosphorous (RP) and expandable graphite (EG) as synergists. The effects of these additives on the combustion behavior of the filled linear low density polyethylene (LLDPE), such as a limiting oxygen index (LOI), the rate of heat release (RHR), the specific extinction area (SEA), etc., have been studied by the LOI determination and the cone calorimeter test. The results show that RP and EG are good synergists for improving the flame retardancy of LLDPE/MH formulations. In addition, a suitable amount of ethylene and vinyl acetate copolymer (EVA) added in the formulations can increase the LOI values while promoting the char formation and showing almost no effect on the RHR and SEA values. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 206–214, 2001

Effect of curprous oxide in combination with molybdenum trioxide on smoke suppression in rigid poly(vinyl chloride)

AbstractFurther investigation of the synergistic effect of smoke suppression between cuprous oxide and molybdenum trioxide in rigid poly(vinyl chloride) (PVC) was carried out by using a cone calorimeter (cone) at a high incident heat flux of 50 kW m−2. Experimental data derived from the cone calorimeter indicated that binary mixtures of Cu2O and MoO3 clearly showed the synergistic effect in reducing smoke by decreasing total smoke production (TSP), average specific extinction area (av‐SEA), and smoke production rate (SPR). This result is in good agreement with that obtained from the NBS smoke chamber. However, the combustion process of rigid PVC could clearly be seen from the heat release rate (HRR), curve, SPR, and fire degradation obtained from the cone test, which could not be determined from the NBS smoke chamber. It was also found that the binary mixture showed the synergistic effect by increasing was also found that the binary mixture showed the synergistic effect by increasing char residue and reducing the fire degradation of the PVC backbone at a high incident heat flux of 50 kW.m−2. All experimental data well supported the early cross‐linking mechanism of the PVC backbone mentioned in the literature and were consistent with the fire degradation behavior obtained from the cone calorimeter.

A study of thermal degradation and decomposition of rigid poly(vinyl chloride) with metal oxides using thermogravimetry and cone calorimetry

An investigation of the effects of CuO, Fe2O3 and MoO3 on decomposition and smoke emission of poly(vinyl chloride) (PVC) in both the flaming mode and the smouldering mode was carried out using a cone calorimeter (CONE) at an incident heat flux of 25 kW m−2. The combination of decomposition of PVC taken from CONE and thermal degradation taken from TGA allows better understanding of the smoke suppressant mechanism of the metal oxides in PVC. The experimental data strongly support an early crosslinking mechanism based upon smoke parameters and the thermal degradation at early stage in both the flaming mode and the smouldering mode. However, the metal oxides significantly enhance the specific extinction area (SEA) at the late stage in the smouldering mode, and reduce the SEA at the late stage in the flaming mode. These facts demonstrate that metal oxides change components of the flaming volatiles evolved during heating at the late stage.

The thermal characteristics of different intumescent coatings

Intumescent coatings are among the most efficient ways of fire retarding flammable materials. The coatings swell under the influence of heat and form a thick porous charred layer. The latter perfectly insulates the substrate against an excessive increase of temperature and oxygen access. In order to make intumescent coatings effective, proper selection of the essential components, i.e. carbonizing, foam-producing and dehydrating materials, is necessary. The choice of components for an intumescent fire retardant composition has an essential effect on the rate of charred mass formation and its structure. The influence of different modifiers added to amino resins during the process of condensation on fire retardant and heat-insulating efficiency of intumescent coatings for wood is presented. The fireproofing efficiency was studied by determining the heat release rate, the effective heat of combustion, the mass loss rate and the specific extinction area during the combustion of samples was investigated. The most efficient coating, both from the point of view of fire retardancy and heat insulating properties, was found to be that based on amino resin prepared from urea, dicyandiamide and monoammonium phosphate and dextrin. The exposing of wood coated with urea-dicyandiamide-phosphate-formaldehyde resin supplemented by dextrin to a heat flux of 35 kW/m2 for 30 min did not result in ignition and no increase occured in heat release, mass loss rates or in effective heat of combustion. Copyright © 1999 John Wiley & Sons, Ltd.

Smoke data determination for various types of fuel

Abstract Fire protection assessment is of major interest in industrial environments. Among the resulting threats, smoke production is the object of growing attention. In this context, a proper analysis of smoke generated by four of the most commonly used oils in the Electricite de France production units, as well as heating oil, often implicated in everyday life accidental fires, is reported. The convenient relative measure of smoke emission, the specific extinction area, is identified as the variable to be used. Results show that all these fuels have a high propensity to generate soot particles. The evolution of extinction coefficient and wavelength, modelled as K e ∼ λ -n , reveals small-size, mainly absorbing particles. However, the dispersion coefficient n appears not spectrally constant. Despite the few data points, giving an exploratory nature to the work, a slope discontinuity of the curves, more or less marked as a function of the atomic ratio H/C of the fuel, appears between the visible and near infrared range of the spectrum. Theoretical predictions using appropriate values of soot optical constants show a satisfactory agreement with experiment. Beyond a simple classification of the different fuels, the results are valuable as input values in radiative exchange modelling.

Propriétés d'extinction des fumées produites par le fioul domestique en combustion vive

A study dealing with the opacity and radiating power of smoke produced during flame combustion of heating oil is conducted. A quantity combining the smoke extinction coefficient, fuel-mass-loss rate and smoke volume flow rate is defined. This quantity, called specific extinction area, is shown to be conserved when varying combustion parameters. Its dependence with respect to radiation wavelength is derived through extinction measurements and compared to the theoretical evolution. Finally, smoke particles are characterized by size and concentration and the possible changes in size and structure of particles, in relation to modifications in environmental conditions, are discussed.

Smoke data from the Cone Calorimeter for comparison with the room fire test

AbstractSmoke production in the full–scale room fire test ISO 9705 (Commonly referred to as the Room Corner Test) and in the Cone Calorimeter ISO 5660 has been analysed for three sets of building products comprising a total of 28 products. The smoke production may be critical for the fire classification of surface products since some products produce large amounts of smoke in the room fire test even if they do not reach flashover within 20 min. Several smoke parameters in the Cone Calorimeter and the room fire test have been analysed. Good correlations have been obtained when the products are divided into two groups: products with more than 10 min to flashover in the room fire test and those with less than 10 min. These two time categories correspond to the two heat output levels in the room fire test: 100 kW for the first 10 min and then 300 kW up to 20 min. For products with more than 10 min to flashover the average rate of smoke production and the total smoke production seem to be useful parameters for predictions of smoke release in the room fire test. Both parameters have good correlations between data from the Cone Calorimeter and the room fire test. For products with less than 10 min to flashover no parameter seems to give useful predictions. For all products evaluated together, the correlations are not so good, but the same regression lines as for products with more than 10 min might be used as a first rough estimate. In this case the total smoke production in the Cone Calorimeter could be used to estimate the total smoke production in the room fire test for different building products, independent of their estimated time to flashover.It is suggested that the average rate of smoke production and the total smoke production from the Cone Calorimeter is reported in addition to the mass‐based specific extinction area. This will be helpful in predicting smoke release in the room fire test and will also make the data on smoke release analogous to those on heat release.

Smoke Release Rates: Modified Smoke Chamber versus Cone Calorimeter-Comparison of Results

In North America, some of the products used in building con struction (e.g., resilient floor coverings, carpets and electrical cable) are regulated using ASTM E 662 Standard Test Method for Specific Optical Den sity of Smoke Generated by Solid Materials. However, technical shortcomings, in this ASTM standard, as symbolized by its many limitations on use, cau tionary statements and caveats, often renders results of E 662 smoke density tests meaningless. In recent years, many leading fire scientists have suggested that the small-scale laboratory test most proficient in illustrating the propen sity of materials to release smoke in larger fires is ASTM E 1354 Standard Test Method for Heat and Visible Smoke Release Rates for Materials and Products Using an Oxygen Consumption Calorimeter (cone calorimeter), and as a result this test procedure has been suggested as an alternative to E 662. Modifica tions were made to the smoke chamber and the procedure for reporting the resulting data so that static smoke generation data produced with the smoke chamber could be related to dynamic smoke release rate data from cone calorimeter tests. The values for peak extinction area for smoke released by four flooring materials (Douglas fir plywood, oak lumber, carpet and resilient flooring) as determined using the modified smoke chamber method were ap proximately one-half the values obtained from the cone calorimeter. However, when specified time intervals were considered, the values for specific extinction area were approximately equal by these two procedures. This suggests that values for specific extinction area are independent of the irradiance to which samples were exposed.

The Effect Of Scale On Smoke Emission

Parallel instrumentation for measuring fire smoke aerosols have been developed in bench scale as part of the Cone Calorimeter, and in large scale in a specially built measuring rig. Since the principles of design were similar, data could be directly compared. For solid and liquid combustibles, it was found that large-scale smoke emission rates could be well represented from Cone Calorimeter data if the specimen mass loss rates per unit area, were matched for the two cases. The matching of the mass loss rates was accomplished in bench scale by exposing the specimen to a suitable level of external irradiance. The results are presented in terms of the specific extinction area, which is defined as the smoke extinction cross-section, per unit mass. The specific extinction area, when computed on a smoke particulate mass basis, was seen to be independent of fuel type and of the conditions of test.

4485234 Method of preparing polyamide acid for processing of semiconductors

Lightweight and fire-resistant isocyanate-based polyimide foams (PIFs) were rapidly formed via a simple one-pot process; polymethylene polyphenylene isocyanate (PAPI) was added into a solution containing refilled aromatic dianhydride. The obtained Fourier transform infrared spectra (FT-IR) showed that the refilled 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride (BTDA) reacted with isocyanate and amino groups in PIFs during the forming and postcuring process. These reactions increased the percentage of polyimide in the foams. Meanwhile, the reaction between refilled BTDA which has a higher reactivity than its derivatives and amino groups, reduced the reaction between isocyanate and amino groups. Subsequently, the generation of ureido was restrained. Thermal gravimetric analysis (TGA) and differential thermogravimetry (DTG) results presented that when the refilled BTDA dosage was increased, the percentage of polyimide and ureido were increased and reduced, respectively. However, the proportion of different ingredients in the PIFs prepared by different formulations was basically the same when the refilled BTDA dosage exceeded 50%. As such, the refilled dosage of BTDA between 50% and 60% was sufficient for this system, the refilled BTDA had extreme effects on enhancing polyimide proportion and reducing the generation of ureido. Fire resistance was characterized by limiting oxygen index (LOI) and cone calorimeter (CCT). Results showed that with the gradual increasing in polyimide proportion of the PIFs resulting from the increase in refilled BTDA dosage, their fire resistance was remarkably improved, which was mainly reflected by the following: gradual increase in LOI value, decrease in heat release rate (HRR), decrease in the peak of HRR (PHRR), decrease in total smoke production (TSP), and decrease in average specific extinction area (ASEA). Compared with the foam prepared without refilled BTDA, the foam prepared with 60% BTDA refilled dosage exhibited increased LOI value from 20.8% to 30.1%, PHRR reduction from 181.91 kW/m2 to 41.54 kW/m2, and significant reduction of HRR. The reduction in TSP and ASEA reached up to 78.2% and 83.1%, respectively. Meanwhile, when the refilled dosage of BTDA exceeded 60%, the LOI value also showed a slower increase. This change was possibly due to the residual BTDA in foams, which acted as a retardant packing role. The density of foams also increased when the post-additive dosage of BTDA was increased. Possible chemical reactions involved in this preparation method of isocyanate-based PIFs were also discussed in this paper.