Lower Heat Release Rate Research Articles

Rheological and fire properties of a composite of unsaturated polyester resin and halogen‐free flame retardants

ABSTRACTThe main subject of the present research is to determine the impact of flame retarding fillers on macroscopic properties of composites. The effect on rheological properties of composition unsaturated polyester resin (UP) and flame retardant blend (FR) consisting of expandable graphite (EG) and or not modified silica and: (1) melamine polyphosphate (MPP) with ammonium polyphosphate (APP), (2) MPP with aluminum trihydrate (ATH), (3) only MPP was examined. Next, their influence on thixotropic properties of UP was estimated. FR fillers were compared according to their grain size, specific surface, and shape factor. Rheological properties were determined by applying hysteresis loop surface and thixotropy factor measuring. For the UP + FR composition, the dependence of grain morphological parameters, such as shape factor and specific surface, on viscosity and hysteresis loop surface was determined experimentally. All of the tested composites consisting of UP + 40% FR blend exhibits high flame resistance. An addition of only 2% of modified silica to all of the FR blends caused significant enlargement of hysteresis loop surface and thixotropy index. Hence, for the next stage of the research (an industrial test of GRP pipes casted by the centrifugal method) FR blend without modified silica was chosen. A composite consisting of UP, MP, APP and EG is characterized by lower heat release rate (HRRmax) (ca. 83%) and lower TSR (ca. 80%), ALMR (55%), and MARHE (73%) in comparison to UP resin; and that UP + FR composition exhibit satisfactory rheological properties as well. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44371.

Investigation of the combustion process of hydrogen jets under argon-circulated hydrogen-engine conditions

The feasibility of argon-circulated hydrogen engines for use in vehicles was recently investigated. The substitution of the noble gas argon (Ar) as the working gas in a hydrogen engine led to the realization of a zero-emission, high-efficiency engine that allows low-ignitability hydrogen to ignite instantaneously after injection. The objective of this study was to investigate the combustion processes of hydrogen jets under argon-circulated hydrogen-engine conditions. Experiments were conducted in a constant-volume combustion vessel under varying conditions with respect to atmosphere, oxygen concentration, injection pressure, ambient temperature, and nozzle-hole diameter. Furthermore, the ignition characteristics and the combustion processes of the hydrogen jets were observed using high-speed shadowgraph images. Under short ignition delay conditions, the experimental results for the Ar–O2 atmosphere indicated a lower heat-release rate, which continued to the end of the injection and resulted in a longer combustion period, whereas the heat-release rate under the air (N2–O2) atmosphere terminated simultaneously with the end of the injection. The ignition delay for the hydrogen jet under an Ar–O2 atmosphere increased with decreasing ambient temperature, similar to the behaviour observed under the air atmosphere. Other fundamental characteristics that may help control the operation of argon-circulated hydrogen engines were obtained and discussed.

An experimental study on temperature evolution inside compartment with fire growth and flame ejection through an opening under external wind

This paper investigated experimentally the temperature evolution inside the compartment as well as the transitions of fire growth from stratified phase to well-mixed case; and the critical conditions for flame ejection outside the opening, under different external wind speed. The characteristic parameters including the temperature inside the compartment, the heat release rate (HRR) of fire growth reaching well-mixed phase, as well as the critical heat release rate (HRR) for flame ejection were measured and discussed. It is found that: (1) For the stratified phase with lower heat release rate, the temperature difference between the upper part and lower part inside the compartment was reduced with increasing wind speed. (2) The maximum temperature that can be reached at the upper part as well as its corresponding HRR was lower when the wind speed was higher. (3) The critical total heat release rates corresponding to reaching the intermittent flame ejection and the continuous flame ejection at the opening both showed to first increase and then decrease with increasing wind speed. The corresponding transitional wind speed for this variation was shown to increase with increasing opening size or ventilation factor (AH). (4) The well-mixed condition was reached after the continuous flame ejection happens with no wind, however, it was reached before the continuous flame ejection shows up for the cases with external wind. The critical HRR for reaching the well-mixed condition decreased with increasing wind speed, which, in a non-dimensional form, correlated well against the wind Froude number by a linear function. These new findings provide a fundamental base for understanding fire growth dynamics inside a compartment with an opening subjected to external wind.

Durable flame retardant finish for silk fabric using boron hybrid silica sol

A hybrid silica sol was prepared via sol gel method using tetraethoxysilane (TEOS) as a precursor and boric acid (H3BO3) as flame retardant additive and then applied to silk fabric. In order to endow silk fabric with durable flame retardancy, 1,2,3,4-butanetetracarboxylic acid (BTCA) was used as cross-linking agent for the sake of strong linkage formation between the hybrid silica sol and silk fabric. The FT-IR and XPS analysis demonstrated the Si-O-B formation in the sol system, as well as the linkage between the sol and silk after the treatment. The limiting oxygen index (LOI) and smoke density test indicated good flame retardancy and smoke suppression of the treated silk fabrics. The micro calorimeter combustion (MCC) test and thermo gravimetric (TG) analysis showed that the treated samples had less weight loss in the high temperature and lower heat release rate when burning. The washing durability evaluation results indicated that there was a distinct improvement for the silk samples treated with BTCA even after 30 times washing. In addition, the influence of the processing order of BTCA and silica sol treatment on the limiting oxygen index (LOI) of the finished silk fabric was also investigated. And the results demonstrated that the sample treated with BTCA first and then with the silica sol exhibited better LOI value (32.3%) than that of the sample by the conversed treatment order. Moreover the tensile property of treated samples was nearly unchanged, but the handle of sol treated samples obviously decreased.

Preparation, Thermal Degradation, and Fire Behaviors of Intumescent Flame Retardant Polypropylene with a Charring Agent Containing Pentaerythritol and Triazine

A macromolecular charring agent named as PEPADC was synthesized by using cyanuric chloride, 2,6,7-trioxa-l-phosphabicyclo[2.2.2]octane-4-methanol (PEPA), and diethylenetriamine and used to prepare intumescent flame retardant polypropylene (IFR-PP) containing ammonium polyphosphate (APP). The effect of flame retardant compound on thermal degradation, flame retardancy, and fire behavior properties of a IFR-PP system has been investigated. The results suggested that the max thermal degradation temperature (Tmax) as well as char residue at 700 °C increased with IFR loading. The highest LOI value of IFR-PP is 35.5, while the IFR loading is 30 wt % and the weight ratio of APP to PEPADC is 4:1. Meanwhile, the IFR-PPs can pass UL-94 V-0 when the weight ratio of APP to PEPADC is between 1:2 and 5:1. Cone calorimetry results indicated that IFR-PPs exhibited much lower heat release rate (HRR), total heat release (THR), specific extinction area (SEA), and total smoke production (TSP) than the neat PP.

N-heptane micro pilot assisted methane combustion in a Rapid Compression Expansion Machine

The autoignition and combustion behaviour of an n-heptane spray in a premixed methane/air charge was investigated. A Rapid Compression Expansion Machine (RCEM) with a free floating piston was employed to reach engine relevant conditions at Start of Injection (SOI) of the micro n-heptane pilot. The methane content in the ambient gas mixture was varied by injecting different amounts of methane directly into the combustion chamber; the ambient equivalence ratio for the methane content ranged from 0.0 to 0.99. Filtered OH∗ chemiluminescence images of the combustion were taken with a UV intensified camera at a rate of 20kHz through the optical access in the piston and schlieren imaging was performed at 20kHz for the detection of density gradients arising from pilot injection, ignition and flame propagation in the unburned mixture. Filtered photomultiplier signals of the total emitted light for OH∗, CH∗ and C2∗ radicals as well as the pressure signal were simultaneously recorded and the effect of methane content, charge temperature and ambient oxygen concentration on ignition locations, ignition timing and combustion behaviour was analysed. It was found that increasing methane contents in the ambient mixture considerably prolongs the ignition delays of the pilot spray due to inhibiting effects of the premixed methane on the reactions leading to high temperature ignition triggered by n-heptane. Longer ignition delays due to lower ambient temperatures or dilution of the ambient oxidizer cause higher heat release during the combustion of the pilot spray, since more methane/air is entrained and mixed with the pilot spray and oxidized simultaneously. This behaviour is reversed with increasing ignition delays arising from increased methane addition. There, lower heat release rates during pilot combustion were observed due to decreased reactivity in the n-heptane spray area. Comparison of different strategies with respect to the determination of high temperature ignition delay highlighted shortcomings as well as the potential in the usage of spectrally filtered chemiluminescence data, since changes in the spectrum of the emitted chemiluminescence are expected to change over time in the case of pilot ignition due to the transition between combustion modes. An assessment of the methane content influence on the ignition reactions by means of homogeneous, adiabatic Perfectly Stirred Reactor (PSR) simulations with a suitable reaction mechanism is further presented which allows for separation of influences and supports the experimental findings.

Flame retardant properties and mechanism of an efficient intumescent flame retardant PLA composites

The charring agent (CNCA-DA) containing triazine and benzene rings was combined with ammonium polyphosphate (APP) to form intumescent flame retardant (IFR), and it was occupied to modify polylactide (PLA). The flame retardant properties and mechanism of flame retardant PLA composites were investigated by the limited oxygen index (LOI), vertical burning test (UL-94), thermogravimetric analysis, microscale combustion calorimetry, scanning electron microscopy, laser Raman spectroscopy analysis and X-ray photoelectron spectroscopy. The analysis from LOI and UL-94 presented that the IFR was very effective in flame retardancy of PLA. When the weight ratio of APP to CNCA-DA was 3:1, and the IFR loading was 30%, the IFR showed the best effect, and the LOI value reached 45.6%. It was found that when 20 wt% IFR was loaded, the flame retardancy of PLA/IFR still passed UL-94 V-0 rating, and its LOI value reached 32.8%. The microscale combustion calorimetry results showed that PLA/IFR had lower heat release rate, total heat release, and heat release capacity than other composites, and there was an obvious synergistic effect between APP and CNCA-DA for PLA. IFR containing APP/CNCA-DA had good thermal stability and char-forming ability with the char residue 29.3% at 800°C under N2 atmosphere. Scanning electron microscopy observation further indicated that IFR could promote forming continuous and compact intumescent char layer. The laser Raman spectroscopy analysis and X-ray photoelectron spectroscopy analysis results indicated that an appropriate graphitization degree of the residue char was formed, and more O and N were remained to form more cross-linking structure. Copyright © 2016 John Wiley & Sons, Ltd.

Combustion Characteristics of Electrolyte Pool Fires for Lithium Ion Batteries

Combustion characteristics of electrolyte pool fires are investigated both theoretically and experimentally under various pan diameters and external heat fluxes using a cone calorimeter. The heat release rate (HRR), mass loss rate (MLR), flame height and gas release rate are measured. Experimental results show that the peak HRR and MLR per unit area are proportional to external heat fluxes and inversely proportional to pan diameters. Dimensionless flame height is observed to decrease under a bigger pan diameter. Peak CO and CO2 production rates increase with a bigger pan diameter or external heat flux, but these two factors show limited influence on the mole ratio of CO/CO2. Comparing to hydrocarbons, the electrolyte has relatively low effective heat of combustion and high heat of gasification which results in lower HRR or MLR, and a higher flame height. An empirical model is developed to predict the peak HRR of the electrolyte pool fire based on pan diameter and external heat flux. Besides, Heskestad's correlation has been improved to predict the average flame height of the electrolyte pool fire by considering the effective heat of combustion, pan diameter and mass stoichiometric ratio of air to fuel.

Component Ratio Effect of Melamine Cyanurate/Magnesium Hydroxide on the Flame-retardant Properties of Ethylene-Propylene-diene Terpolymer Rubber

A synergistic flame-retardant compound containing magnesium hydroxide (MH) and melamine cyanurate (MCA) ingredients was prepared with ethylene-propylene-diene monomer (EPDM) composite to find a highly efficient, halogen-free, and phosphorus-free flame retardant. The flame-retardant MH/MCA compound particles were modified by a silane coupling agent to increase surface activity. Two series of EPDM/MH/MCA composites were prepared by direct blending methods. The mechanical and flame-retardant properties of the composites were investigated by various methods. The Rockwell hardness and tensile strength of EPDM/MH/MCA composites significantly increased after adding MH/MCA compound particles compared with EPDM composites. Results showed that incorporating MH/MCA compound particles evidently improved the flame-retardant and mechanical properties of EPDM. Both of these properties increased, and the flame-retardant properties of the materials met the UL94 V-1 requirements. The excellent properties of the composites were obtained after adding 40 phr MH and 20 phr MCA with a silicane coupling agent. Results indicated that the EPDM/MH/MCA composite with the appropriate MH/MCA mass ratio had the highest LOI, UL94 V-0 rating, lowest heat release rate, and highest residue yield. These results implied that the appropriate MH/MCA mass ratio formed a better flame-retardant system and adequately exerted their synergistic effects. Different flame-retardant performances should be attributed to their own characteristics, dispersion state in EPDM matrix, and the change of structure during burning.

Biocomposites from waste derived biochars: Mechanical, thermal, chemical, and morphological properties

To identify a route for organic wastes utilisation, biochar made from various feedstocks (landfill pine saw dust, sewage sludge, and poultry litter) and at diverse pyrolysis conditions, were collected. These biochars were used to fabricate wood and polypropylene biocomposites with a loading level of 24 mass%. The composites were tested for their mechanical, chemical, thermal, morphological, and fire properties. The poultry litter biochar biocomposite, with highest ash content, was found to have high values of tensile/flexural strength, tensile/flexural modulus, and impact strength, compared to other composites. In general, addition of all the biochars enhanced the tensile/flexural moduli of the composites. The crystal structure of polypropylene in the composite was intact after the incorporation of all the biochars. The final chemical and crystal structure of the composite were an additive function of the individual components. The biochar particles along with wood acted as nucleating agents for the recrystallization of polypropylene in composite. Each component in the composites was found to decompose individually under thermal regime. The electron microscopy revealed the infiltration of polypropylene into the biochar pores and a general good dispersion in most composites. The poultry litter composite was found to have lower heat release rate under combustion regime.

인도네시아 주요 조림수종의 연소특성

본 연구에서는 인도네시아 조림지에서 생장한 4수종의 효율적 활용방안을 마련하기 위해 콘칼로리미터법에 의해 연소특성을 조사하였다. 그 결과, 평균열방출량(<TEX>$HRR_{mean}$</TEX>)은 비중에 비례하였으며, 총열방출량(THR) 및 연소시간(FT) 등열관련 계수도 같은 경향을 나타냈다. Albizia는 열방출 시간이 짧았고, Mindi는 4수종 중 점화시간(TTI)과 연소시간(FT)이 길어져 4수종 중 연소속도가 늦었고, 열방출 시간도 가장 길게 이어져 결국은 Mangium 수종과 비슷한 총열방출률을 나타내는 것을 확인할 수 있었다. Albizia는 공시수종 중 가장 높은 비소화면적 값을 나타내어 연기발생비율이 높았고, 반대로 Mindi는 가장 낮은 비소화면적 값을 나타내 연기발생비율이 낮았다. 초기 연기방출률은 Albizia가 높았으나 이후에는 Gmelina와 Mangium 의 연기방출률이 높아져 총연기발생량이 높게 나타났다. Gmelina는 불완전연소로 인해 연소기간 중 가장 많은 일산화탄소 연기를 생성하였고, <TEX>$CO/CO_2$</TEX> 비율은 다른 수종에 비해 3배 이상 높았다. This study was performed to understand combustion properties four major Indonesian wood species such as Albizia, Gmelina, Mangium and Mindi were investigated by cone-calorimeter for better utilization of theses wood species. Heat release rate (HRR), total heat release (TSR), specific mass loss rate (SMLR), effective heat of combustion (EHC), time to ignition (TTI), flame time (FT), specific extinction area (SEA), smoke production rate (SPR) and CO compound production rate were measured. HRR, THR and FT were proportional to the density of woods. Albizia showed the highest HRR, while Mindi had the lowest HRR. For SPR, Albizia showed the highest value due to its higher SEA. On the other hand, Mindi had the lowest SPR due to a lower SEA value. The highest smoke emission was for Albizia at the beginning of combustion. After 300 seconds, smoke emission of Gmleina and Mangium was increased greatly. Mangium and Mindi showed the highest total carbon dioxide emission. Expecially, Gmelina released the highest carbon monoxide during the combustion period and presented three times higher <TEX>$CO/CO_2$</TEX> ratio than those of other species due to incomplete combustion.

Preparation of multi‐walled carbon nanotubes and its application as flame retardant for polypropylene

NiO catalyst supported on Fe-pillared montmorillonite (5–15 wt% Ni) was prepared via a simple conventional impregnation method. The physicochemical properties of the Ni catalyst were characterised by X-ray diffraction, inductively coupled plasma-atomic emission spectrometry and transmission electron microscopy. The Ni catalyst, together with organic montmorillonite (OMMT), was employed to prepare multi-walled carbon nanotubes (MWCNTs) by using polypropylene (PP) as a precursor. An increase in Ni loading of the catalyst led to a significant increase in the yield of MWCNTs at the expense of a slight decline in quality of the obtained MWCNTs. Moreover, OMMT altered the degradation process of PP, which resulted in a much higher fraction of light hydrocarbons in degradation products. As such, a substantial increase in the yield of MWCNTs was attained. In addition, the obtained MWCNTs were used as flame retardant for PP, and significantly enhanced thermal stability and flame retardancy according to thermogravimetry analysis and cone data, respectively. PP/MWCNTs nanocomposite exhibited higher degradation temperature, longer ignition time, much lower heat release rate and smoke production rate. This work offers an efficient Ni catalyst to convert PP into MWCNTs which could be applied as flame retardant for polymers.

A sustainable, eugenol-derived epoxy resin with high biobased content, modulus, hardness and low flammability: Synthesis, curing kinetics and structure–property relationship

To develop functional sustainable epoxy resins, we report a novel epoxy resin (DEU-EP) with high net biobased content (70.2wt%) derived from renewable eugenol. We comparatively study DEU-EP with a commercial bisphenol A epoxy resin (DGEBA) in the presence of a diamine curing agent, 4,4′-diaminodiphenyl methane (DDM). Differential scanning calorimetry reveals that DEU-EP can be sufficiently cured by DDM at a slower rate than DGEBA. By applying an autocatalytic reaction kinetic model we adequately simulate the curing rate of DEU-EP/DDM, and reveal its detailed kinetic mechanisms from model-free isoconversional analysis. Dynamic mechanical analysis shows that DEU-EP/DDM takes the higher storage modulus up to ∼97°C than does DGEBA/DDM with the glass temperature of 114°C. Nanoindentation and thermogravimetric analyses demonstrate that compared with DGEBA/DDM, DEU-EP/DDM exhibits a 20%, 6.7% and 111% increase in Young’s modulus, hardness and char yield, respectively. Microscale combustion calorimetry data show that DEU-EP/DDM expresses 55% and 38% lower heat release rate and total heat release than does DGEBA/DDM, respectively. The horizontal burning test approves DEU-EP/DDM can self-extinguish in a short time. Our results demonstrate that the eugenol building blocks and their arrangement greatly affect the cure behaviors of DEU-EP/DDM, and contribute significantly to its enhanced mechanical properties, high-temperature charring ability and chain motions at the glassy state, as well as the reduced flammability. To summarize, DEU-EP exhibits a high promise as a new sustainable epoxy monomer for fabricating high biobased content, high rigid and low flammable epoxy materials.

Surface modification of ammonium polyphosphate-diatomaceous earth composite filler and its application in flame-retardant paper

Ammonium polyphosphate (APP)-diatomaceous earth (DE) composite prepared by in situ polymerization was modified with silane coupling agent (KH550) and was applied as filler to prepare flame-retardant paper. Fourier transfer infrared, X-ray diffraction and thermogravimetry were used to characterize the structure and properties of the fillers, and limiting oxygen index (LOI), cone calorimeter and field-emission scanning electron microscope were used to investigate the flame-retardant properties of the filled paper. Results showed that chemical bonds occurred between APP-10 % DE filler and KH550, and APP-10 % DE filler had lower water solubility and better crystallization and thermostability after it was modified with KH550. Paper filled with modified APP-10 % DE filler had higher LOI value and lower heat release rate and mass loss at the same filler loading, and its charred residue collected after cone calorimeter test was more compact and strong. Surface modification of APP-10 % DE filler with KH550 improves its flame-retardant effect on paper.

Potential of double pilot injection strategies optimized with the design of experiments procedure to improve diesel engine emissions and performance

Abstract The potential of pilot–pilot–main triple injection strategies versus engine-out emissions, combustion noise and brake specific fuel consumption has been assessed experimentally on a Euro 5 diesel engine with a reduced compression ratio (16.3:1). The engine has been fueled with conventional diesel fuel. The experimental tests on the engine have been carried out in a dynamometer cell under different steady state working conditions, that are representative of passenger car engine applications over the European homologation cycle. Furthermore, in-cylinder analyses of the pressure, heat-release rate, temperature and emissions have been performed in order to obtain more detailed knowledge on the cause-and-effect-relationships between the implemented injection strategies and the results of the experimental tests. The implemented double-pilot injection engine calibrations have been optimized by means of the design of experiments procedure. The plotted data of the engine performance and emissions have been compared with data from the original double-injection schedule, characterized by a retarded main injection timing, in order to intensify the premixed combustion phase. The benefits and the disadvantages of the PCCI concept are preliminarily discussed, on the basis of the experimental pilot–main injection strategy results. The substitution of the pilot–main injection schedule with the triple injection, for light engine loads and low engine speeds, has led to higher mean combustion pressures, lower heat release rates, shorter ignition delays and lower brake specific fuel consumption. Above all, a significant improvement in engine noise and in both CO and HC engine-out emissions has been achieved and the NO x emission have been limited by the application of high EGR rates. When medium engine loads and speeds are analyzed, the considered double-pilot injection strategy allows the NO x emissions to be reduced, compared to the baseline pilot–main injection schedule. However, the combustion noise does not improve and the soot deteriorates, even though the soot penalties are not relevant.

Performance, combustion, and emissions in a diesel engine operated with fuel-in-water emulsions based on lignin

Abstract We report for the first time on the use of water-continuous emulsions stabilized by a bio-based macromolecule in a compression-ignition diesel engine and compare their performance, combustion and emissions against the base fuels (diesel, biodiesel, and jet fuel). For this purpose, high internal phase ratio emulsions (70:30 fuel-to-water) were produced by mechanical emulsification using carboxymethylated wood lignin as stabilizer. Combusting experiments were performed with the engine operating at 2000 rpm under three loads (0, 1.26 and 3.26 bar brake mean effective pressure, BMEP). Engine performance, in-cylinder combustion, and exhaust emissions were monitored and compared for the fuels tested. At no load condition and when compared to the respective base (single phase) fuels, an increase in the indicated work was observed for diesel and biodiesel emulsions. Compared to the base fuels, the emulsions resulted in higher engine mechanical efficiency at 1.26 and 3.26 bar BMEP except for jet fuel emulsion at 1.26 bar. Additionally, they displayed a lower brake specific fuel consumption (BSFC), if calculated on the basis of effective fuel content discounting emulsion water, and higher brake thermal efficiency. Compared to the base fuel, the respective emulsions generally presented lower peak in-cylinder pressure, lower heat release rates, and longer ignition delays at 1.26 bar and 3.26 bar BMEP; the opposite effect was observed at no-load conditions. Remarkably, a large reduction of nitrogen oxides (NOx) emissions was noted in the combustion of the fuel emulsions, which was accompanied with a relatively higher carbon monoxide (CO) release at 1.26 and 3.26 bar (at 0 bar BMEP, the emulsions produced less CO emissions). The effect of emulsions on hydrocarbon emissions and smoke opacity depended on the fuel type and the engine load. Overall, it is concluded that while reports on fuel emulsions involve oil-continuous systems, the proposed water-continuous alternative represents an opportunity for diesel engines, whereby the fuel is dispersed as micrometric droplets for improved combustion and reduced emissions. At the same time, the fuel emulsion formulation takes advantage of the surface activity and high calorific value of widely available, inexpensive lignin stabilizers, making the proposed system a viable option towards cleaner or fully bio-based fuels.

Comparative study on synergistic effect of LDH and zirconium phosphate with aluminum trihydroxide on flame retardancy of EVA composites

Flame-retardant ethylene vinyl acetate (EVA) composite based on aluminum trihydroxide (ATH), layered double hydroxide (LDH) and organo-modified zirconium phosphate (mZrP) were prepared by melt-compounding method. The synergistic effect of LDH and mZrP with ATH on the fire behavior and thermal stability of EVA composites was studied by limiting oxygen index, UL-94 test, cone calorimeter and thermogravimetric analysis. EVA composite with ATH and LDH passed the V-0 rating while EVA composite with ATH and mZrP exhibited relatively low peak heat release rate. EVA/ATH composite with 10 mass% LDH exhibited a char yield of 34 % at 700 °C, while its counterpart with 10 mass% mZrP showed 29 %, indicating LDH possessed superior flame-retardant synergistic efficiency with ATH over mZrP in terms of promoting char formation. Regarding the heat release rate (HRR), EVA/ATH composite with 10 mass% mZrP displayed a 73 % reduction in PHRR, whereas its counterpart with the equivalent loading of LDH showed a lower flame-retardant synergistic efficiency (a 58 % reduction in peak HRR). The results above demonstrated that LDH mainly functioned as catalyst in char formation, while mZrP was beneficial to restraining heat release.

Combustion properties of cotton fabric treated by boron doped silica sol

Cotton fabric was treated with pure silica sol and boron doped partner through sol-gel method in order to improve its thermal and combustion properties. The results of thermo-gravimetric analysis, micro combustion calorimeter, and smoke density test of control showed that the finished cotton fabric had excellent thermal stability and mild combustion behavior with lower heat release rate. Furthermore, the smoke density test also indicated the safety performance of the boron doped silica sol treated cotton fabric in the fire.

Effect of two-stage injection on combustion and emissions under high EGR rate on a diesel engine by fueling blends of diesel/gasoline, diesel/n-butanol, diesel/gasoline/n-butanol and pure diesel

The effect of two-stage injection on combustion and emission characteristics under high EGR (46%) condition were experimentally investigated. Four different fuels including pure diesel and blended fuels of diesel/gasoline, diesel/n-butanol, diesel/gasoline/n-butanol were tested. Results show that blending gasoline or/and n-butanol in diesel improves smoke emissions while induces increase in maximum pressure rise rate (MPRR). Adopting pilot injection close to main injection can effectively reduce the peak of premixed heat release rate and MPRR. However, for fuels blends with high percentage of low cetane number fuel, the effect of pilot fuel on ignition can be neglected and the improvement of MPRR is not that obvious. Pilot-main interval presents more obvious effect on smoke than pilot injection rate does, and the smoke emissions decrease with increasing pilot-main interval. A longer main-post interval results in a lower post heat release rate and prolonged combustion duration. While post injection rate has little effect on the start of ignition for post injection. The variation in fuel properties caused by blending gasoline or/and n-butanol into diesel does not impose obvious influence on post combustion. The smoke emission increases first and then declines with retard of post injection timing. Compared to diesel, the smoke emissions of blended fuels are more sensitive to the variation of post injection strategy.

Layered double hydroxide-based fire resistant coatings for flexible polyurethane foam

Montmorillonite clay (MMT) is frequently used to create fire resistance in Layer-by-Layer (LbL) applied coatings. This manuscript reports that switching the MMT with layered double hydroxides (LDH) produced a more effective fire resistant coating on flexible foam. Most of the formulations required at most two trilayers (TL) to produce ignition resistant and very low heat release rate polyurethane foam. The best coating (greatest flammability reduction with the least amount of coating) delivered a 41% reduction in peak heat release rate. This was a 2TL, 10% mass coating produced using a coating solution with a high LDH content. This manuscript discusses the impact of the LDH-based coating formulations and number of monolayers on the LbL coating growth rate, composition, and fire resistance.