Flame Spread Index Research Articles

Eco-friendly preparation of advanced epoxy composites and their pyrolysis and flame retardant mechanisms

Traditional additive flame retardants pose issues including high dosage, easy precipitation, and poor compatibility with the matrix. Designing efficient organic-inorganic synergistic flame retardants can enhance the flame retardancy and mechanical properties of epoxy (EP) composites while reducing their smoke toxicity. In our study, we initially employed Tetrakis(hydroxymethyl)phosphonium sulfate (THPS) for intercalation modification of montmorillonite (MMT). Subsequently, we achieved a green and efficient exfoliation of MMT by reacting urea with hydroxyl groups, resulting in the simultaneous preparation of efficient organic/inorganic synergistic flame retardants (THPSU-MMT). EP composites containing 5wt% THPSU-MMT can attain UL-94 V0 classification. Furthermore, the peak heat release rate (PHRR), total heat release (THR), and peak release rates of CO can be reduced by up to 78.42 %, 62.26 %, and 72.50 %, respectively. Simultaneously, we systematically investigated the synergistic flame retardant mechanism of the EP composite. The findings reveal that THPSU-MMT exhibits a dual flame retardant effect in both the gaseous and condensed phases. Moreover, the combination of MMT and THPSU substantially enhances the presence of phosphorus-containing pyrolysis products in the condensed phase. The fire performance index (FPI) of the flame retardant EP increased from 0.05 m2/s/W in pure EP to 0.36 m2/s/W, attributed to the enhanced catalytic carbonization and assisted gas-phase free radical capture. Additionally, the flame spread index (FGI) decreased from 11.55 kW/m/s in pure EP to 1.18 kW/m/s, signifying a substantial enhancement in fire safety. Furthermore, the THPSU-MMT synergistic flame retardants improved the tensile strength of EP composites. This study offers an environmentally friendly and efficient approach for the effective exfoliation of MMT, while also presenting novel concepts for the design of efficient organic-inorganic synergistic flame retardants.

Pyrolysis and combustion characteristics of typical sealing materials for exterior building windows

Seals play a crucial role in preventing flame penetration through building exterior windows. However, as urban renewal accelerates, the number of discarded seals is also gradually increasing, which is not in line with the concept of green, energy-saving sustainable development. To gain a better understanding of the pyrolysis and combustion characteristics of sealing strips and facilitate their effective resource utilization and conversion into value-added fuels, we employed thermogravimetry, cone calorimetry, and flue gas spreading test equipment. Typical sealing and filling materials used for external windows of buildings, including EPDM ordinary adhesive strips (EPDM-O), EPDM flame-retardant adhesive strips (EPDM-R), as well as 20-fold expanding graphite strips and 30-fold expanding graphite strips (EG-20 and EG-30), were investigated. Comprehensive evaluations of their pyrolysis behaviors, kinetic parameters, and combustion characteristic parameters were carried out. The results showed that EPDM exhibits good thermal stability, while EG had better demonstrates favorable pyrolysis properties and expansion densification. Average activation energies of EPDM-O and EPDM-R in the combustion phase were 68.35 kJmol−1 and 92.40 kJmol−1, respectively. Moreover, the average activation energies of EG-20 and EG-30 in the expanding combustion phase were 67.42 kJ·mol−1 and 68.62 kJ·mol−1, respectively. The reaction rate of combustion stage is faster than that of pyrolysis stage. Furthermore, For the combustion, the flame growth index (FGI) of EPDM is greater than that of EG, whereas the flame spread index (FPI) is lower than EG. When EPDM burns, the flame spreads rapidly, while EG expands and generates a large number of wormlike substances, effectively preventing the high temperature from spreading to the interior of the material. Analyses of smoke spreading tests have shown that both EPDM and EG can produce irritating flammable fumes at high temperatures, affecting the environment. These results provide a basis for the development of new materials and contributes to fire safety, smoke management, and personnel escape planning.

A Review on Flame Retardants Used in Polyurethane Foam

The present review summarizes the research work about different flame retardants used for polyurethane foam along with NBC (National Building Codes) and standards. With growing market of polyurethane foam, properties such as flame spread index, smoke release, and nature of fumes generated during and after catching the fire is of great importance and other properties, i.e., compression strength, tensile strength, hardness, elongation at break, etc. These will differ as type and loading of flame retardants used during formulation will vary.

Synergistic effect of clam shell bio-filler on the fire-resistance and char formation of intumescent fire-retardant coatings

Clamshell (CS) bio-filler derived from clam shells was produced and then applied as a synergist in waterborne intumescent fire-retardant coatings. Fire protection and smoke density tests show that the combination of CS bio-filler and intumescent flame retardant (IFR) exhibits excellent synergistic effect on reducing the flame spread index (FSR), char index, weight loss, equilibrium backside temperature and smoke density rating (SDR) of the intumescent coatings. Especially, the FC-3 sample containing 52 wt% IFR and 3 wt% CS bio-filler exhibits the lowest FSR and SDR values, which are 68.3% and 37.3%, respectively, lower than those of FC-0 sample with 55 wt% IFR. The results from the accelerated ageing test show that the combination of IFR and CS imparts super durability of smoke suppression and flame-retardant properties to the intumescent coatings, exhibiting excellent anti-ageing properties. Char residue analysis demonstrates that the FC-3 sample containing 3 wt% CS bio-filler shows higher mass ratios of O/C, N/C and P/C than those of FC-0 without CS bio-filler, indicating more P, N and O-containing cross-linking structures remained in the FC-3 char, thus imparting high char-forming ability and thermal stability to the coatings, as supported by the results of thermogravimetric (TG) analysis and Fourier transform infrared spectroscopy (FTIR) analysis.

Influence of modifiers on coked foam structure and properties formed with thermal decomposition of wood

Wood is a material that forms a surface layer of coke when burning. Properties of the coke layer significantly impact the fire resistance of structures due to the change of the structure working section reduction rate. This paper discusses the research of how the wood surface layer modifiers influence the structure and properties of the coke layer formed with thermal decomposition of wood. As modifiers have been used phosphorus flame-retardants. To evaluate how the modifiers influence the coke layer formation process, the source and modified samples of pine have been analyzed before and after thermal decomposition using the element analysis, electron microscopy, and adsorption. Thermal analysis has been accomplished using the thermogravimetry (TG), differential thermogravimetry (DTG), and differential scanning calorimetry. To evaluate the fire protection efficiency of the modified wood, fire tests have been accomplished. Such tests were tests to determine the magnitude of weight loss during combustion, flame spread index and the coefficient of smoke-ability. Based on the acquired data, it was identified that when the modifiers are used, and these modifiers enter into efficient superficial chemical reaction with wood under mild conditions, the thermal decomposition occurred under mild conditions - the first stage of thermal decomposition transits to the lower temperatures zone. This reduces the thermal effect of thermal decomposition reaction. There is a decrease in weight loss during thermal decomposition. This results in formation of the strong and structured, thermally stable surface, which is less adsorption ability, specific surface area and porosity reduction. This explains high rate of fire protection and low smoke-generating capacities.

Investigation of Factory Fire Retardant Treatment of Eucalyptus Plywood

Abstract Eucalyptus has become an important substitute material for the burgeoning plywood industry in China, whereas the corresponding fire retardant–treated products remain to be developed. This study preliminarily evaluated the feasibility of manufacturing fire retardant–treated eucalyptus plywood in the traditional industrial plant by veneer impregnation. Eucalyptus saligna and Eucalyptus dunnii veneers were impregnated by a commercial fire retardant at room temperature and atmospheric pressure. After redrying, the veneers were hot pressed into fire retardant–treated plywood in a conventional way. Fire performance was evaluated by cone calorimeter test. Basic properties (i.e., moisture content, bonding strength, and formaldehyde emission), mechanical properties (including modulus of rupture and modulus of elasticity), and hygroscopicity were also investigated. The fire retardancy of plywood was significantly improved by the fire retardant treatment, in terms of decreased heat release rate and increased residual mass fraction. The flame spread index values for plywood, which were calculated from the results from cone calorimeter tests, indicate that the fire performance of plywood improves from Class III to Class II after the treatment. The basic properties of fire retardant–treated plywood meet the requirements of GB/T 9846 (Standardization Administration of the People's Republic of China 2004). The mechanical and hygroscopic properties of fire retardant–treated plywood satisfy demands of general interior applications. The veneer treatment could be a suitable approach for Eucalyptus plywood factories to manufacture fire retardant–treated products.

Siloxanes synthesized “in situ” by sol–gel process for fire control in wood of Araucaria angustifolia

Panels of Araucaria angustifolia were chemically modified with alkoxysilanes, hydrolyzed and condensed “in situ” by the sol–gel process. Alkoxysilanes selected were aminopropyl methyldiethoxysilane (A), aminopropyl triethoxysilane (B) and a mixture of both (C). Ethanol was used as solvent in 4/1 ethanol/alkoxide molar ratio. The pH was adjusted to alkaline value for controlling the kinetic of hydrolysis–condensation reactions.Impregnation process was carried out at 45–50°C in an autoclave, controlling the operating conditions for achieving different weight gains.Laboratory tests were carried out in Two-Foot Tunnel (flame spread index, panel consumption and smoke density) and in TGA detector (mass loss).The performance in laboratory tests can be explicated according the reactivity of the alkoxides. The results support the conclusion that the best fireproof efficiency was observed in woods treated with the alkoxide B, followed by those modified with the mixture C and the alkoxide A, in this order; the results also indicates that as weight gain increased the performance of impregnants against fire.

Fire Performance Properties of Solid Wood and Lignocellulose-Plastic Composite Deck Boards

Traditionally fire performance properties of externally located deck boards have been characterized by their flame spread index (FSI) as determined by UL 723/ASTM E 84. In this test a nominal 0.6 m wide by 7.3 m long array of deck boards is exposed to an approximately 90 kW ignition source fire for 10 min in the Steiner Tunnel. More recently the University of California Forest Products Laboratory developed a new fire test protocol based the principles of oxygen consumption calorimetry, California SFM 12-7A-4, Part A: Under-Deck Flame Test. This protocol addresses the potential ignition of a deck from underneath as may occur during a wildfire. In this protocol a nominal 0.44 square meter deck-system of deck boards mechanically fastened to wood joists is subjected to an 80 kW ignition source fire for 3 min. For this study the fire performance characteristics of more than thirty-five deck board types were evaluated by the above two methods and by a smaller-scale material-based test, ASTM E 1354 cone calorimeter. Deck boards were selected to represent a range of materials (untreated wood, lignocellulose-polymer composite), structures (solid, voided, microcellular foam), and cross-sectional profiles (width, thickness, presence of hidden fastener system longitudinal edge grooves). The results from this study were used to: 1. Develop correlations for deck boards between the material-based cone calorimeter tests and system-based under-deck tests. 2. Develop correlations for deck boards between the small-scale cone calorimeter tests and large-scale Steiner Tunnel tests. 3. Estimate the significance of ASTM D 2898 Method A accelerated weathering on fire performance.

Performance Tests of Surface Burning for Firestop Materials

To prevent improper design and construction of fire compartments through-penetration in buildings, and in order to reinforce public building safety management, all beams, pillars, ceilings, floors, doors, walls, and interior decorative materials must have fireproof properties. Moreover, cable conduits, water pipes, and air ducts located in through-penetration sites within buildings should be properly designed to block the spread of smoke and hot air, thus, reducing losses due to fire disasters. This study used common firestop materials, such as firestop sheets, mineral wool, and two-pack fire barrier foam to conduct 10-min surface burning tests on individual substrates. The flame spread distance and smoke per minute were measured and recorded in order to calculate the Flame Spread Index (FSI) and Smoke Developed Index (SDI). The results showed that all three firestop materials meet with the ASTM E84 Class A.

Fire performance and decay resistance of solid wood and plywood treated with quaternary ammonia compounds and common fire retardants

In this study, the fire performance and decay resistance of solid wood and plywood treated with quaternary ammonia compounds (didecyl dimethyl ammonium chloride (DDAC) and didecyl dimethyl ammonium tetrafluoroborate (DBF)) were compared with the performance of untreated control specimens and specimens treated with common fire retardants ((monoammonium phosphate (MAP), diammonium phosphate (DAP) and ammonium sulphate (AS)). Test specimens were treated with 1% and 4% (% m/v) aqueous solutions of the chemicals. The fire performance tests were the fire tube test (ASTM E 69) which measures mass losses in the specimens and the cone calorimeter test (ASTM E 1354) which measures mass loss, heat release rate, time for sustained ignition, effective heat of combustion, and specific extinction area. The results from the cone calorimeter tests were used to estimate the flame spread index (FSI) in the Steiner tunnel test (ASTM E 84). Heat release rates of the specimens treated with MAP, DAP, and AS were lower than those of both DDAC and DBF-treated specimens and the untreated control specimens. Compared with the untreated specimens, higher heat release rates were observed for the specimens treated with the quaternary ammonia compounds, DDAC and DBF. The estimates for the FSI for DDAC and DBF were for values equal to or higher than for the untreated control specimens. At higher concentration levels, MAP, DAP and AS were effective in decreasing initial contribution of heat release to potential fire. Decay resistance tests were done according to AWPA E 10 standard method using one brown-rot fungus and one white rot-fungus. Decay resistance tests revealed that solid wood specimens treated with DDAC and DBF showed resistance against the fungi tested, however, MAP, DAP and AS did not provide complete protection. While DBF and DDAC increased resistance of plywood specimens, high mass losses in plywood specimens treated with MAP, DAP and AS were obtained.

Flame-retardant impregnants for woods based on alkaline silicates

The aim of this paper was to determine the fire performance of wood panels ( Araucaria angustifolia) impregnated in a pressure vessel with post-cured alkaline silicates (water glasses). Several commercial silicates based on sodium ions and potassium ions with 3.0/1.0 and 3.5/1.0 silica/alkali molar ratios were selected. Various treatments for curing were applied for polymerization, creating metal silicate polymers of high water insolubility. Experimental panels were tested in a limiting oxygen chamber (limiting oxygen index) and in a two-foot tunnel (flame-spread index and panel consumption). Test results displayed a high fire-retardant efficiency of some post-cured alkaline silicates.

Zinc borates as flame-retardant pigments in chlorine-containing coatings

This paper discusses the influence of zinc borates with molecular formulas of 2ZnO·3B 2O 3·3.5H 2O and 2ZnO·3B 2O 3·7.5H 2O used for substituting antimony trioxide on the performance of chlorinated alkyd, flame-retardant coatings. Experimental coatings were manufactured on a laboratory scale, applied by brush on wood panels (Araucaria Angustifolia) and finally tested in a limiting oxygen chamber (LOI values), in a flame cabinet (intermittent bunsen burner rating) and in a two-foot flame tunnel (flame-spread index, panel consumption, after-flaming and after-glow). Results of laboratory tests indicated that coatings with a chlorine-containing resin used as the film-forming material, zinc borates can act as a flame retardant.

Enhancement of Biological and Physical Properties of Wood by Boric Acid-Vinyl Monomer Combination Treatment

Boron treatment was combined with vinyl polymerization to improve leaching resistance of boron from wood, as well as dimensional stability, biological and fire resistance of wood. Boric acid (BA) was impregnated into wood specimens [sapwood of Cryptomeria japonica D. Don. 20 (T) x 20 (R) x 10 (L)mm] as 1% aqueous solution prior to vinyl monomer treatment. Styrene (ST), methylmetacrylate (MMA) and their mixtures (50:50, v/v) were impregnated in the presence of catalyzer and a crosslinker. Polymerization was conducted by heat radiation method at 90°C for 4h. Treated specimens were then subjected to decay and termite tests, as well as oxygen index (O.I) determination. Anti-swelling efficiency (ASE) and water absorption levels (WA) were also measured by standardized methods. Vinyl monomers succeeded in reducing WA of wood to a minimum level and delay boron leaching considerably. The treated wood proved to be resistant against two decay fungi, Tyromyces palustris and Coriolus versicolor and very destructive termite Coptotermes formosanus even after ten severe weathering cycles. BA increased the O.I. levels of monomer-treated wood, which resulted in a lower flame spread index. Moreover, BA suppressed the smoke generation due to monomer cooperation in wood.

Flame spread properties of forest products. Comparison and validation of prescribed Australian and North American flame spread test methods

AbstractNineteen forest products in sawn board and panel form (including three fire retardant treated) have been tested to AS1530.3—Test For Early Fire Hazard Properties of Materials and ASTM E84—Standard Test Method for Surface Burning Characteristics of Building Materials. These tests are used in the building codes to regulate the flame spread properties of all combustible building materials in Australia and interior finsihes in North America, respectively. A correlation was established between Time to Ignition (AS1530.3) and Flame Spread Index (ASTM E84) for the forest products that had not been fire retardant treated. Room fire testing of eight of the forest products validaded Time to Ignition (AS1530.3) and Flame Spread Index (ASTM E84) as reliable test criteria for regulating the use of combustible materials.

Tackable acoustical structure

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Review of ASTM Test for Surface Burning Characteristics of Building Materials (E 84) (An ASTM White Paper)

AbstractThis review of ASTM Test for Surface Burning Characteristics of Building Materials (E 84) is intended to provide a source document on the 25-ft tunnel test method as well as to provide a basis for its evaluation by ASTM Subcommittee E05.32 on Research. It covers the history of ASTM E 84 including its development and acceptance by the regulatory authorities. It describes the test method as it exists today and the current operational and calculational procedures. It discusses the work of the tunnel operator's task group in continually reviewing the method, conducting research, and proposing revisions for consideration for adoption by ASTM Committee E-5 on Fire Standards. The effect of air velocity, burner gas flow, and other variables on the results of the test and the reproducibility between testing laboratories is discussed. The correlation of the results of the tunnel tests with those of room and corner tests is presented. The present state of the analysis of the tunnel is described. The efforts to determine the total quantity of smoke produced during the test by improving the photometer system, eliminating stratification, and changing the calculational procedures are discussed. The oxygen consumption method for determining the total heat contribution is described. The benefit of reporting the rate of flame spread as well as the flame spread index (FSI) is pointed out. The advantages and disadvantages are discussed. A list of ASTM E 84 test facilities along with the person to contact is provided. A comprehensive bibliography of the tunnel is included.

Steiner tunnel index as a measure of flame spread rate

The procedure by which a flame spread index is calculated in the Steiner Tunnel Test has recently been revised by ASTM. The new index is shown to measure average flame speed, weighted so as to emphasize the flame behavior in the earlier part of the test.

Flammability characteristics of fiber reinforced organic matrix composites

AbstractThe effect of resin, fiber, and fire retardant additives on flammability characteristics of organic matrix composites was evaluated. Information is presented on the flame spread index, determined by the radiant panel test, the amount of smoke generated, and products of combustion, using the National Bureau of Standards Smoke Density Apparatus, and the amount of oxygen required to support combustion using the Oxygen Index method. These methods were effective in screening the flammability characteristics of organic matrix composites. Of the materials evaluated the polyimide composites were the most resistant to flame spread, exhibited the lowest evolution of smoke and toxic products and had the highest oxygen index. No differences in flame spread and oxygen index were observed for the polyester epoxy glass‐cloth laminates. Addition of antimony trioxide and hydrated alumina to the polyester and epoxy resin systems significantly decreased the flame spread index and increased the oxygen index, but showed a marked increase in smoke evolution. Smoke properties depended on resin content whereas the type of reinforcement did not appear to affect flame spread index or smoke properties. The use of protective barriers in selected shipboard areas can reduce flame spread and lengthen the lime for generation of smoke.