Fire Retardant Additives Research Articles

Pyrolysis of polyurethane foam: optimized search for kinetic properties via simultaneous K–K method, genetic algorithm and elemental analysis

SummaryThis study focuses on the determination of kinetic properties for non‐fire retardant (NFR) and fire retardant (FR) polyurethane foams. Based on the experimental thermogravimetric (TG) curves, this paper describes the application of an in‐depth mathematical analysis and genetic algorithm (GA) to produce the kinetic properties. A recent developed technique, K–K method, is used for calculating kinetic properties and determining the search regions of these properties for GA. Elemental analysis is also used to study the pyrolysis mechanism. Three decomposition models were investigated for comparison, and the results show that the decomposition model with three sub‐reactions achieves the closest representation with experimental results. In the model, two sub‐reactions capture the foam and melt decompositions, and another sub‐reaction with relatively lower activation energy captures the early onset of foam decomposition. The kinetic properties of melt decomposition are found similar because of the similarity of melt chemical formulas and decomposition of NFR and FR foams. The kinetic properties of foam decomposition between NFR and FR foams are different because of the mechanism of FR additives. Validation of the successive and parallel reaction schemes shows no noticeable difference between the two schemes in the modelling decomposition. Copyright © 2015 John Wiley & Sons, Ltd.

Oriented Clay Nanopaper from Biobased Components—Mechanisms for Superior Fire Protection Properties

The toxicity of the most efficient fire retardant additives is a major problem for polymeric materials. Cellulose nanofiber (CNF)/clay nanocomposites, with unique brick-and-mortar structure and prepared by simple filtration, are characterized from the morphological point of view by scanning electron microscopy and X-ray diffraction. These nanocomposites have superior fire protection properties to other clay nanocomposites and fiber composites. The corresponding mechanisms are evaluated in terms of flammability (reaction to a flame) and cone calorimetry (exposure to heat flux). These two tests provide a wide spectrum characterization of fire protection properties in CNF/montmorrilonite (MTM) materials. The morphology of the collected residues after flammability testing is investigated. In addition, thermal and thermo-oxidative stability are evaluated by thermogravimetric analyses performed in inert (nitrogen) and oxidative (air) atmospheres. Physical and chemical mechanisms are identified and related to the unique nanostructure and its low thermal conductivity, high gas barrier properties and CNF/MTM interactions for char formation.

The combination of aluminum trihydroxide (ATH) and melamine borate (MB) as fire retardant additives for elastomeric ethylene vinyl acetate (EVA)

Fire retardancy and smoke release of ethylene vinyl acetate (vinyl acetate content of 60%, EVA) with aluminum trihydroxide (ATH) and melamine borate (MB) was evaluated by mass loss cone calorimetry, limiting oxygen index (LOI), UL-94 and a home-made smoke test and compared to materials already reported in literature. It was found that the combination of ATH and MB results in improved fire retardant properties as well as in decrease smoke release in comparison to the virgin polymer. To evaluate the contribution of MB in the material, the decomposition mechanism of EVA-ATH-MB was examined. First, using scanning electron microscopy (SEM), it was shown that ATH and MB are evenly dispersed in the polymeric matrix. The thermal decomposition of EVA-ATH-MB was investigated by thermogravimetric analysis (TGA). Gases released in a fire scenario were analyzed using mass loss calorimeter coupled with a Fourier transform infrared spectrometer (MLC-FTIR). The condensed phase of EVA-ATH-MB was examined using solid state nuclear magnetic resonance (NMR) of 13C, 27Al and 11B. Moreover, thermal conductivity of EVA-ATH-MB in function of the temperature was measured and compared to that of EVA-ATH materials containing melamine (MEL) or melamine phosphate (MP) instead of MB. It was found that EVA-ATH-MB is protected through a gas and a condensed phase mechanism, whereas MB contributes to the formation of a protective layer due to formation of boron oxide, boron nitride and BNO structures at the sample surface. The formed boron species further lead to decrease of the thermal conductivity in the range of the ignition temperature of the polymer leading to ignition at longer times of EVA-ATH-MB in comparison to the other tested materials.

폴리인산염 첨가에 의한 폴리프로필렌 기반의 Wood Plastic Composites 열안정성

본 연구에서는 WPC의 열안정성을 향상시키기 위해 폴리프로펠렌 매트릭스에 목분과 폴리인산염(ammonium polyphosphate, APP)의 삼종혼합 후, 목분과 난연제 첨가에 따른 목재플라스틱 복합재(wood plastic composites, WPC)의 열분해 거동이 조사되었다. 모든 배합비의 WPC 열분해 거동은 질소의 환경에서 분당 <TEX>$10^{\circ}C$</TEX> 상승속도로 제어하여 열중량분석기(Thermogravimetric analyzer)를 통해 분석하였다. 목분의 열분해온도가 PP의 열분해온도 보다 낮기 때문에 목분에 의해 생성된 char막은 PP로의 열전달 속도를 낮추며, 2차 열분해온도 증가 및 열분해속도를 늦춘다. APP를 첨가한 WPC의 경우 1차 열분해온도 감소 및 2차 열분해온도의 증가를 보여준다. 목분의 함량이 높은 WPC의 경우, APP 첨가 시 1차 열분해온도 감소 및 2차 열분해속도가 증가하였고, 고온에서 잔여물의 양은 APP 함량이 증가할수록 크게 증가하였다. APP가 첨가된 WPC 경우, 목분의 함량이 10 wt%에서 50 wt%로 증가 시 고온에서 잔여물 양이 증가하였는데, 이는 APP 및 목질섬유의 char화가 동시에 발생되기 때문으로 보이며 결과적으로 목분 함량이 증가할수록 APP의 효과가 높게 나타나 열안정 효과를 관찰할 수 있었다. In order to improve the thermal stability of wood plastic composites (WPC), thermal degradation behavior of WPC in this study was investigated by the addition of wood flour and fire retardant after hybridization of wood flour and ammonium polyphosphate (APP) into polypropylene (PP) matrix. Thermal degradation behavior of all formulations was analyzed with thermogravimetric analyzer under nitrogen environment at heating rate of <TEX>$10^{\circ}C/min$</TEX>. As the thermal degradation temperature of wood flour is lower than that of PP, char layer formed by the wood flour decreases the speed of heat transfer to PP. In addition, the char layer increases the 2nd thermal degradation temperature and decreases the 2nd thermal degradation speed. The WPC treated with APP increases the 1st and 2nd degradation temperatures. In the case of WPC with high loading level of wood flour, the 1st thermal degradation temperature and 2nd thermal degradation rate were increased by the addition of APP, and then the amount of remnants at high temperature was increased by the increase of the APP loading level. In the case of WPC treated with APP, the amount of the remnants at high temperature was increased with the increase of wood flour content from 10 wt% to 50 wt%, indicating that char formation of the APP and wood flour occurred at the same time, resulting in high thermal stability effect by the increase of wood flour content.

The effect of electron-beam irradiation and halogen-free flame retardants on properties of poly butylene terephthalate

Abstract Engineering plastics like Poly (butylene terephthalate) due to their desirable properties have various industrial applications. Neat PBT is highly combustible, so it is necessary to improve significantly its fire retardancy to meet the fire safety requirements. The combustion performance of PBT can be improved by addition of appropriate flame retardant additives. In this study we have investigated the effect of halogen free flame retardants, i.e. melamine and aluminum phosphate, and instantaneously electron beam radiation-induced crosslinking in the presence of Triallyl cyanurate on various properties of PBT. The results of gel content showed that a dose range of 200–400 kGy leads to high cross linked structure in this polymer. Also mechanical experiments showed that its structure became rigid and fragile due to irradiation. Radiation crosslinking of this polymer made its dielectric loss coefficient ten times lower than non-irradiated polymer, but had no effect on its dielectric constant. Moreover the addition of the fire retardant additives as impurity decreased the dielectric loss coefficient. TGA analysis in nitrogen exhibited that irradiation increases char formation and use of the fire retardant additives leads to reduction of onset temperature and formation of higher char quantity than pure PBT. According to the results of UL-94, irradiated samples burned with lower speed and less dripping in vertical and horizontal positions than pure polymer. Finally irradiation of the polymers containing fire retardant additives with a dose of 400 kGy led to self-extinguishing and non-dripping and reach to V-0 level in the UL-94 V.

Performance Study Analysis of Inflaming Retarding Viscose of Clothing Material

This paper makes test of degree of polymerization and molecular weight of common and inflaming retarding viscose in clothing material. And then it analyzes the effect of degree of polymerization and molecular weight on material fiber thermology and mechanical property. The research shows that the addition of fire retardant reduces degree of polymerization and molecular weight of material fiber, enhances flame retardant performance, and reduces mechanical property. Through the test research, we deeply compare the performance of inflaming retarding and common viscose on clothing material, which offers related reference value for the development of inflaming retarding function garment materials.

Cone calorimeter study of polyethylene flame retarded with expandable graphite and intumescent fire-retardant additives

Polyethylene was flame retarded with two intumescent-type additives, 3,5-diaminobenzoic acid phosphate and ethylenediamine phosphate, which differ with respect to their decomposition onset temperatures, along with varying ratios of two grades of expandable graphite, also differing with respect to their onset temperatures for exfoliation. Hot-pressed sheet specimens were subjected to evaluation in a cone calorimeter. Although the best char yields were obtained with formulations containing the higher decomposition temperature intumescent, 3,5-diaminobenzoic acid phosphate, the overall best performance was realized using the lower decomposition temperature intumescent, ethylenediamine phosphate, when compounded together with the low exfoliation temperature expandable graphite. These results are attributed to the formation, at the burning surface, of a more cohesive char with better thermal and mass transfer barrier properties.

Improved Safety, High Performance Electrolytes for Li-Ion Batteries

Rechargeable lithium-ion batteries with improved safety and high performance are needed for numerous applications including electric vehicles, consumer electronics, and military platforms. Current lithium-ion batteries typically utilize an electrolyte composed of a lithium salt (e.g. LiPF6) and flammable organic solvents (e.g. ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, etc.). Using conventional flammable electrolytes, current lithium-ion batteries can combust under failure mechanisms such as overcharging, internal shorting, defects, physical damage, overheating, etc. Non-flammable electrolytes are currently being developed to provide Li-ion batteries that do not catch fire under failure or abuse conditions. Various non-flammable electrolytes based on ionic liquids, phosphates, phosphonates, and other fire retardant additives have been developed to provide non-flammable lithium-ion conducting electrolytes. However, most non-flammable electrolytes developed to date result in decreased battery performance, particularly under high rate (≥3 C) and low temperature conditions (≤ -30 ºC) which are required for numerous applications. Improved electrolytes are needed to meet the performance and safety requirements of next generation Li-ion batteries. For the electrolyte, needed properties include (i) adequate ionic conductivity over the desired temperature range, (ii) the ability to form stable and conductive interfaces with the anode and cathode, (iii) high temperature stability, and (iv) flame retardant properties. The electrolyte composition is a compromise between these factors, and different electrolyte compositions are needed depending on the application’s temperature range, electrode materials, rate, etc.We have explored the development of Li-ion conducting electrolytes that are both non-flammable and provide high performance through developing mixtures composed of salts, solvents and additives. Electrolytes were prepared in an inert atmosphere (Argon) glovebox. Electrolyte properties measured included ionic conductivity versus temperature and flammability. Flammability was measured using multiple methods: wick test, flash point, oxygen consumption calorimetry, and simulated venting. The performance of the electrolyte was evaluated in lab-scale cells (coin and pouch) over various charge/discharge rates and temperatures. Electrochemical impedance spectroscopy was used to probe the interfacial resistance.From our analysis, we determined that the solvents, co-solvents, and additives used within typical electrolytes have different flammabilities. In addition, the different flammability tests showed differing results indicating that the nature of the test plays a critical role and differing experimental test conditions can lead to widely varied flammabilities. Using the information determined from flammability testing, we developed electrolyte mixtures designed to provide wide temperature operation, high rates, and be flame retardant. Electrochemical testing of the electrolyte in half and full cells showed that the electrolyte composition affected the battery’s capacity, cycle life, low temperature performance and high temperature performance. Electrochemical impedance spectroscopy results showed that specific electrolyte compositions resulted in similar charge transfer resistances as conventional flammable electrolytes. Full cells using specifically designed electrolytes exhibited similar capacities at low temperatures (-40 ºC) and at high rates (5C) as cells using baseline electrolytes. From current testing performed, electrolytes containing specific flame retardant compounds, interfacial formers, and wide temperature components have the capability to provide batteries with significantly lower flammability and similar capacities, rates, cycle lives, and temperature ranges as batteries with conventional flammable electrolytes.

Experimental and computational investigations on fire resistance of GFRP composite for building façade

Composite materials such as glass fibre reinforced polymers (GFRPs) possess the advantages of high strength and stiffness, as well as low density and highly flexible tailoring; therefore, their potential in replacing conventional materials (such as concrete, aluminium and steel) in building façade has become attractive. This paper addresses one of the major issues that hinder the extensive use of composite structures in the high-rise building industry, which is the fire resistance. In this study, a fire performance enhancement strategy for multilayer composite sandwich panels, which are comprised of GFRP composite facets and polyethylene foam core, is proposed with the addition of environmentally friendly, fire retardant unsaturated polyester resins and gel-coats. A series of burning experimental studies including thermo-gravimetric analysis (TGA) and single burning item (SBI) are carried out on the full scale composite sandwich as well as on single constituents, providing information regarding heat release rate, total heat release, fire growth rate, and smoke production. Experimental results are compared with fire safety codes for building materials to identify the key areas for improvements. A fire dynamic numerical model has been developed in this work using the Fire Dynamics Simulator (FDS) to simulate the burning process of composite structures in the SBI test. Numerical results of heat production and growth rate are presented in comparison with experimental observations validating the computational model and provide further insights into the fire resisting process. Parametric studies are conducted to investigate the effect of fire retardant additives on the fire performance of the composite sandwich panel leading to optimum designs for the sandwich panel.

Synergy Effects of Wood Flour and Fire Retardants in Flammability of Wood-plastic Composites

Addition of wood flour improve the mechanical properties of thermoplastics, on the other hand it increases the burning speed of the materials. To modify the flammability of wood-plastic composites(WPC), various fire retardants, such as ammonium polysphosphate (APP), melamine polyphosphate (MPP) and aluminum hydroxide were added to WPCs. Burning tests based on UL94 and cone calorimetry were conducted to evaluate a fire performance of WPCs with fire retardants. The addition of fire retardants could lead to self-extinguishing materials when 10 wt% of APP was used. However, in the case of pure polypropylene, addition of 10 wt% of APP did not improve the flammability. Wood flour accelerates the burning behavior of PP, but it can reduce the use of APP to achieve self-extinguishing materials. Synergy effects between wood flour and APP was confirmed. Wood flour facilitates the forming of foamed char layer by APP during the combustion. This protective char surface can reduce the heat and oxygen diffusion toward the WPCs. The effect of fire retardants of mechanical properties of WPCs was also investigated. Tensile strength and modulus of composites decreased with addition of fire retardants.

Fire propagation performance of intumescent fire protective coatings using eggshells as a novel biofiller.

This paper aims to synthesize and characterize an effective intumescent fire protective coating that incorporates eggshell powder as a novel biofiller. The performances of thermal stability, char formation, fire propagation, water resistance, and adhesion strength of coatings have been evaluated. A few intumescent flame-retardant coatings based on these three ecofriendly fire retardant additives ammonium polyphosphate phase II, pentaerythritol and melamine mixed together with flame-retardant fillers, and acrylic binder have been prepared and designed for steel. The fire performance of the coatings has conducted employing BS 476: Part 6-Fire propagation test. The foam structures of the intumescent coatings have been observed using field emission scanning electron microscopy. On exposure, the coated specimens' B, C, and D had been certified to be Class 0 due to the fact that their fire propagation indexes were less than 12. Incorporation of ecofriendly eggshell, biofiller into formulation D led to excellent performance in fire stopping (index value, (I) = 4.3) and antioxidation of intumescent coating. The coating is also found to be quite effective in water repellency, uniform foam structure, and adhesion strength.

Improvement on fire retardancy of wood flour/polypropylene composites using various fire retardants

The addition of wood flour improves the mechanical properties of thermoplastics, but also increases the burning rate of neat plastics profoundly. To modify the flammability of wood-plastic composites (WPCs), various additive-type fire retardants such as ammonium polyphosphate (APP), melamine polyphosphate (MPP), and aluminum hydroxide were added to improve the fire performance of WPCs. Both UL94 flame tests and cone calorimetry were used to evaluate the fire performance of WPCs, and the results proved that the addition of 10 wt% APP lead to enhanced self-extinguishing properties. On the other hand, polypropylene with 30 wt% of APP did not achieve self-extinguish properties. The effective parameters in the cone calorimetry test to give self-extinguishing properties were discussed by comparing the results of the burning tests. It was presumed that the most important parameters for self-extinguishing of WPCs was an average heat release rate at initial stage of burning. The effect of fire retardants on the mechanical properties of WPCs was also investigated. The tensile strength and modulus of the composites decreased with the addition of fire retardants.

Influences of montmorillonite on fire protection, water and corrosion resistance of waterborne intumescent fire retardant coating for steel structure

Organic-modified montmorillonite (OMMT) was used as nano-layer filler to improve the fire protection, water and corrosion resistance of waterborne intumescent fire retardant coating. The influence of OMMT on the properties of fire retardant coating and the mechanism of OMMT effect on the coating were investigated in detail by X-ray diffraction (XRD), scanning electron microscope (SEM), thermogravimetric (TGA) analysis, Fourier transform infrared spectroscopy (FTIR), fire protection test, water and corrosion resistance test. It was found by XRD that OMMT could be exfoliated and dispersed well in the coating with the addition of 1wt.%, while excessive OMMT was easy to aggregate and dispersed badly. SEM micrographs and EDS analysis results showed that well-dispersed OMMT nano-layers were parallelly distributed in the coating. The results of fire protection test and the observation results of morphology of char layers indicated that the fire protection of the coating and foam structure of the char layer were remarkably improved by adding suitable content of OMMT. TGA analysis demonstrated that OMMT could enhance the combustion residual weight and thermal stability of the coating. Based on the results of water and corrosion resistance test, the parallel-arranged OMMT could significantly slow down the migration and solvation of fire retardant additives through its barrier effect, thereby improving the water and corrosion resistance of the coating.

Influence of nano-boron nitride on anti-aging property of waterborne fire-resistive coatings

The influence of nano-boron nitride (BN) with a multilayered structure on the anti-aging property of fire-resistive coatings was studied. After accelerated weathering for 20 days, the thermal stabilities and fire protection of the coating without nano-BN were significantly decreased, but the coating modified by nano-BN still maintained excellent intumescent effect and fire protection. The results indicated that nano-BN could improve the anti-aging property of the coatings remarkably. FTIR and XPS characterizations suggested that nano-BN with a multilayered structure could prevent the migration behavior of the hydrophilic fire-retardant additives and keep the fixed ratio of those additives in the coating. TGA results demonstrated that nano-BN could effectively enhance the thermal stabilities of the aged coatings and improve the anti-oxidation property of the char layers formed by the coatings. XRD and EDS results proved that the anti-oxidation of the aged coatings under high temperature could be enhanced effectively after adding nano-BN. SEM observations illustrated that nano-BN addition was beneficial to the improvement of the foam structure of the aged coating.

INFLUENCE OF FIRE RETARDANT ADDITIVES ON FIRE PROPERTIES OF MATERIALS BASED ON POLYESTER RESIN POLIMAL 1033 APY

To investigate the influence of special additives – fire retardants – on the selected fire properties of materials based on polyester resin Polimal 1033 APy produced in the chemical plant ‘Organika-Sarzyna’ in Poland, a full scale of fire methods has been used. Three samples have been studied during combustion in a closed compartment: an unmodified sample, a sample containing 14% of MoO3 (molybdenum trioxide) and a sample containing 14% of antimony trioxide (Sb2O3). Several important parameters related to the combustion of tested polyester materials have been obtained as a result of the undertaken studies such as temperature and carbon monoxide (CO) concentration. This paper discusses the outcome of the conducted full-scale studies. Special emphasis is placed on analysis showing variation in time of these parameters during the combustion of three different polyester materials with and without fire retardant additives. One of the most important parameters taking into account evacuation conditions is time, for reaching the critical value of both temperature and CO concentration that has also been considered in the study. The performed research has demonstrated that the application of the selected additives in the polyester material, in our case Polimal 1033 APy, has enhanced fire resistance of the material mainly by a significant delay of a growth in temperature and CO concentration and almost twice-reduced CO generation, particularly in the case of adding Sb2O3.

Thermal and fire retardant properties of polyurea

Summary — The thermal and fire retardant properties of polyurea, formed by the polyaddition reaction of a modified diisocyanate with an oligomeric diamine, have been studied using thermogravimetric analysis and cone calorimetry as the principal tools. Approximately forty different conventional fire retardant additives including halogens (chlorine and bromine), phosphorus (nearly all oxidation states), mineral fillers, melamine compounds and intumescent additives were used at constant loading of 15 wt. % for all samples (except mineral fillers, 30 wt. %) and evaluated in polyurea. The thermal properties (onset, maximum degradation temperature and char residue) of filled polyurea samples are compared with the control sample. The fire retarded polyurea samples have been screened on the basis of the percentage reduction of peak heat release rate and

Flame retardancy of bio-based polyether-block-amide polymer (PEBAX)

Bio-based polymers are becoming an important class of polymers. This paper deals with the enhancement of flame retardancy properties for the bio-based polymer Pebax, a polyether-block-amide copolymer. Fire retardancy of Pebax with melamine combined with an organomodified montmorillonite clay (cloisite) as fire retardant additives is evaluated by cone calorimetry and limiting oxygen index (LOI). It is found that the best fire retardant properties are observed for a material containing 70 wt% Pebax, 26 wt% melamine and 4 wt% cloisite. To get a better understanding of the role of cloisite, the mechanism of action is investigated for this material compared to a material containing 70 wt% Pebax and 30 wt% melamine. The dispersion of the additives is first examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It is found that all additives are well dispersed in the matrix. Further the thermal degradation, the condensed and the gas phase mechanism of both materials were investigated using thermogravimetric analysis (TGA), solid state nuclear magnetic resonance (NMR) of 13C and of 27Al and thermogravimetric analysis coupled with a Fourier transform infrared spectrometer (TGA–FTIR).It is shown that the material containing only melamine is protected through a gas phase mechanism. Thereby melamine and its degradation products protect the material through a gas phase mechanism. The replacement of 4 wt% melamine by cloisite results an additional protection of the material via condensed phase mechanism. A char layer, that acts as a physical barrier is formed during combustion. Concurrently, melamine and its degradation products act in the gas phase.

Proposed Fire Screening Tests on Plastic Foams with a Cone Calorimeter in Hong Kong

Many big building fires happened in the past involved burning furniture foam. In some places such as Hong Kong, foams treated with fire retardant additives are only required to test their ignitability under a small flame. It was proposed earlier that the behaviour of furniture foam in flashover fires should be assessed more extensively by a cone calorimeter under high radiative heat fluxes. In this paper, this screening approach is further studied using five samples, including three different pillow foams, one mattress foam and one expensive fire-safe sofa foam. Both thermal and smoke aspects were studied in a cone calorimeter under heat fluxes of 20 kWm-2, 30 kWm-2, 50 kWm-2 and 70 kWm-2. It was observed that all the foam samples were burnt under heat fluxes above 30 kWm-2. Only one pillow foam sample was not ignited under a low incident heat flux of 20 kWm-2, but it morphed into a mixture of solid and liquid. Under heat fluxes above 30 kWm-2, the fire-safe foam burnt vigorously; the burning showed no differences from foam without fire retardant. The fire-safe foam even released more smoke and toxic gases with higher carbon monoxide concentration. From the above cone calorimeter test, foams commonly used in the market can only withstand small match fires to delay ignition time. Foam products should be protected by additional provisions, such as an external cover, to protect them against big fires.

Polymer concrete with recycled PET: The influence of the addition of industrial waste on flammability

The civil construction sector has found use for a range of industrial waste products in the form of substitutes that are as effective as standard construction materials but which have the bonus of providing an ecologically sound alternative for materials that would otherwise become an environmental concern. The use of waste materials in cement and polymer composites is a prime example of this practice. While composites with polymer matrices may display excellent mechanical properties, they must also offer superior flammability resistance. The main aim of this study is to develop innovative polymer concrete composites produced with industrial alumina waste, a by-product of the steel industry. The composites used unsaturated ortoftalic polyester as binder, river sand as aggregate and fly ash as filler. Different compositions of flame retardants were tested, one with polishing alumina (residue) and one with commercial grade alumina, and these were used in concentrations of 15%, 30%, 45% and 60% by weight of resin. The properties assessed were mechanical strength, fire propagation and SEM/EDS image analysis and the results underwent statistical analysis to check for their significance. The compositions with the addition of 60% flame retardant waste showed a reduction of 85% in flame propagation times when compared with the samples without the addition of fire retardants and this was accompanied by increased mechanical resistance. No significant difference was found for the two types of flame retardant in terms of flame propagation time.

Development of polyureas with improved fire resistance

The demand for improved damage control materials to address high strain rate impact has led to exploration of polyureas in this role. Polyureas show potential for retrofitting pre-existing platforms because they can be applied as a spray and have extremely fast cure times and low volatile organic compounds. However, they have been limited in use in enclosed spaces because of their flammability. In this article, synthetic and additive routes to improve polyurea flame retardancy are systematically explored. The US Department of Defense test method standard Military Standard 2031 has been used as a target to meet or exceed for flammability properties. This article will outline the changes in polymer chemistry, the addition of fire-retardant additives, and the use of ignition barrier coatings that led to a composition that exceeded the military standard.