Peak Heat Release Research Articles

Influence of Hydroxypropyl methylcellulose (HPMC) on the hydration characteristics and early phase composition of C3S-gypsum binary paste

To further understand the influence of HPMC on cement-based material (CBM) hydration, this study investigates the hydration characteristics and early product formation of C3S-gypsum binary pastes with HPMC. Results demonstrated that HPMC significantly delayed heat release peak occurrence, with the most pronounced effect on induction period duration, which was increased by 1-2 times with adding HPMC. Calculations employing the Krstulovic-Dabic hydration kinetic model show that HPMC most significantly extended the nucleation and crystal growth (NG) stage, increasing the duration by 21% in the 0.05% HPMC group. Additionally, the 0.035% HPMC group showed a 2.6% decrease in CSH gel and 14% in Ca(OH)2 generation after 1 day, while also reducing the chemically bound water (CBW) content by 20%, with CBW relative content variations correlating with hydration stage rate constants. This study confirms that HPMC delays C3S-gypsum hydration and reduces early product generation, aiding future regulation of CBM hydration processes.

Synthesis of a Bimetallic-Doped Phytate-Melamine Composite as an Efficient Additive for Epoxy Resins with High Fire Safety.

The issue of hazardous smoke and toxic gases released from epoxy resins (EP), which often causes casualties in real fires, has limited its application. Therefore, we have developed a novel flame retardant based on a bimetallic-doped phytate-melamine (BPM) structure with Zn2+ and Fe2+ ions incorporated into the polymer matrix using a straightforward solution-based synthetic method. The combustion performance of the composite was evaluated using a cone calorimeter test, which showed that the peak heat release, total heat release, and total smoke production were reduced by 50%, 31.7%, and 29.2%, respectively, compared to those of EP. Additionally, the fire growth index was noticeably reduced by 60% owing to the synergistic catalytic effect of the bimetallic ions, and the high nitrogen and phosphorus content of the additives. Overall, this study provides new insights into the application of bimetallic doping for flame retardant polymer composites.

Improvement of Engine Combustion and Emission Characteristics by Fuel Property Modulation

The sustainability of diesel engines has come to the forefront of research with the growing global interest in reducing greenhouse gas emissions and improving energy efficiency. The aim of this paper is to support the goal of sustainable development by improving the volatile properties of diesel fuel to promote cleaner combustion in engines. In order to study the effect of diesel fuel volatility on spraying, combustion, and emission, the tests were carried out with the help of the constant volume chamber (CVC) test rig and an engine test rig, respectively. CVC test: A high-speed video camera recorded the spray characteristics of different volatile fuels in a constant-volume combustion bomb. The effects of different rail pressures and ambient back pressures on the spray characteristics were investigated. Engine test: The combustion and emission characteristics of different volatile diesel fuels under different load conditions (25%, 50%, 75%) were investigated in a four-stroke direct-injection diesel engine with the engine speed fixed at 2000 rpm. The test results show that as the rail pressure increases and the ambient pressure decreases, the spray characteristics of the fuels tend to increase; for the more volatile fuels, although reducing the spray tip penetration, the spray projected area and spray cone angle increase, which is conducive to improving the homogeneity of the fuel and air mixing in the cylinder. The improvement of fuel volatility can form more and better-quality mixtures within the ignition delay time (ID), resulting in a 1–2% increase in peak cylinder pressure and a 2–4% increase in peak heat release. For different loads, pre-injection heat release is generated to redefine the ID and combustion duration (CD). Improved fuel volatility effectively reduces carbon monoxide (CO) emissions by about 8–10% and hydrocarbon (HC) emissions by about 13–16%, but it increases nitrogen oxide (NOx) emissions by about 8–11%. Analyzing from the perspective of particulate matter (PM), combined with the aromatic content of volatile fuels, it is recommended to use fuels with moderate volatility and aromatic content under low load conditions, and at medium to large loads, the volatility of the fuel has less weight on particulates and more weight on aromatics, so it is desirable to use the fuel with the lowest volatility and lowest aromatic content of the fuel selected.

Orientation control of magnetically functionalized graphene oxide nanohybrids in unsaturated polyester resin with enhanced mechanical, thermal, and fire safety performance

AbstractBoth the distribution and orientation of 2D graphene nanomaterials in polymer matrices can significantly affect the performance of polymer composites. Still, preparing high‐performance graphene polymer nanocomposites with a controlled distribution state is challenging. In this work, magnetically functionalized graphene oxide (MFGO), a ternary nanohybrid, was prepared using a facile method. The resulting MFGO nanofillers were incorporated into unsaturated polyester resin (UPR) with the assistance of an external magnetic field to achieve oriented alignment in the UPR matrix. Attributing to the uniform dispersion as well as the magnetic field‐induced orientation of MFGO in UPR, the oriented UPR/MFGO (UPR/OMFGO) nanocomposites demonstrated much‐improved mechanical and thermal properties, as the oriented UPR/MFGO2.0 (UPR/OMFGO2.0) achieved a notable increase in tensile strength to 46.71 MPa and storage modulus to 1.24 GPa. Moreover, the peak heat release rate (PHRR) and peak smoke production release (PSPR) of UPR/OMFGO2.0 nanocomposite were reduced by 34.0% and 33.6%, respectively, as compared with the neat UPR. In addition, SEM, FTIR, and Raman spectroscopy were employed to investigate the char residues of UPR samples, and a possible mechanism for the improved fire safety performance of the UPR/OMFGO nanocomposites was proposed. This work provides a promising strategy to design high‐performance UPR nanocomposites.Highlights Magnetically functionalized graphene oxide (MFGO) nanohybrids were successfully synthesized. MFGO nanohybrids were well dispersed and orderly arranged in UPR under a magnetic field. The well‐oriented MFGO significantly improved the mechanical and thermal properties of UPR. The mechanism for the enhanced fire safety performance of UPR nanocomposites was elaborated.

The Toxicity Leaching and the Cement Admixtures Properties with Incineration Fly Ash of Different Furnace Types.

Incineration of fly ash is a hazardous solid waste, and there are two types of furnaces used for production. The impact of furnace types on the properties and toxicity of incineration fly ash was studied. The resource utilization of incineration fly ash has been tested. The results showed that circulated fluidized bed (CFB) ash and grate (GF) ash were alkaline materials, dioxin content ranged between 98 and 359 ng-TEQ/kg, and heavy metals exceeded 7700 ppm. The leaching of Zn in CFB ash was 110.474 ppm, and that in the GF ash was 5.985 ppm. The chlorine content in GF ash was 27.07%, 2.7 times that of CFB ash. When the content was 5%, GF ash promoted cement grinding and improved the 3-day compressive strength of cement, which was 35.55% higher than the control sample. CFB ash generates hydrogen gas during the hydration process, causing volume cracking. When 20% GF ash was added, the hydration heat release peak appeared 10.5 h ahead of time. According to the Chinese standard GB 175-2023, the maximum dosages of CFB ash and GF ash in cement were 0.22 and 0.57%. There was no risk of excessive leaching of heavy metals. During cement production with CFB and GF ash, attention should be paid to the issues of chlorine and dioxins.

Interface engineering of MXene towards highly fire-safe epoxy resin with enhanced thermal conductivity

The integration of superior flame retardancy and enhanced thermal conductivity of epoxy resins (EP) is highly desirable for practical applications. Herein, novel organophosphorus-decorated MXene hybrid flame retardant (PMXene) was prepared by the interface engineering between melamine diphenylphosphinate (MDP) and two-dimensional titanium carbide (MXene). With the loading of 6.0 wt% PMXene, the EP/6.0PMXene material achieved a V-0 rating during the UL 94 testing besides the high limiting oxygen index (35.2 %). Cone calorimetric results revealed that the peak of heat release, peak of smoke release rate and smoke factor values of EP/6.0PMXene were reduced by 36.6 %, 27.6 % and 48.6 %, respectively, in comparison with those of pristine EP. Besides, the PMXene hybrid enhanced the thermal conductivity of EP to 0.38 W/m·K, a 52.0 % improvement over pristine EP. Thus, this work provides a novel strategy for fabricating thermosetting materials with high fire-safety and enhanced thermal conductivity.

Fire-safe and mechanically robust polycarbonate composite enabled by novel copolymerization/macromolecular blending strategy

Polycarbonate is a widely used engineering plastic material, but its limited flame retardancy has restricted its application in high-end fields such as aviation and railways. In this study, we propose a novel copolymerization/macromolecular blending strategy to produce a high-performance, fire-safe polycarbonate composite. By copolymerizing with polydimethylsiloxane oligomer and blending with macromolecular polyarylate, the resulting PC-BPDMS5/PITR successfully achieved a UL-94 V-0 rating and a high limiting oxygen index value of 34.2 %. The peak heat release and total smoke release were significantly reduced by 45.2 % and 27.4 %, respectively, compared to pure PC. SEM, Raman, and XPS analyses confirmed the condensed-phase dominated flame-retardant mechanism, attributed to the char-forming ability of the polyarylate and polydimethylsiloxane segments. Polydimethylsiloxane segments can decompose to produce small molecules such as methane, and the left structure with silicon, which undergo cross-linking reactions with the substrate during combustion to promote char formation. The polyaromatic ring structure of PITR can also participate in the formation of a dense and stable char layer. The excellent compatibility between the polyarylate and the PC matrix, combined with the superior flexibility of polydimethylsiloxane, allowed the composite to maintain mechanical properties comparable to pure PC. Additionally, the increased molar volume resulted in a low dielectric constant for PC-BPDMS5/PITR. This work presents a promising approach for the development of high-performance polycarbonate composites.

Performance of sandwich type fire-resistant flexible composite phase change material PEE@EBF for battery thermal management and runaway protection

To mitigate the risks of overheating and thermal runaway in lithium-ion batteries, this study proposes a novel sandwich-type fire-resistant flexible composite phase change material (CPCM), referred to as PEE@EBF. The core material (PEE) was created by melt-blending paraffin wax (PW), expanded graphite (EG), and ethylene–vinyl acetate copolymer (EVA). The outer layer, a fire-resistant coating (EBF), was applied to the surface of PEE and consists of epoxy resin (EP), boron nitride (BN), and the composite flame retardant (CFR). Test results demonstrated that PEE@EBF maintained structural integrity, exhibiting no significant deformation or leakage after being heated at 80 °C for 5 h. PEE@EBF also displayed a high latent heat of 166.6 J/g, thermal conductivity of 0.8 W/(m∙K), and excellent electrical insulation properties. Furthermore, it achieved a UL94 V-0 flame retardant rating, with notable reductions in peak heat release rate (PHRR) and peak smoke production rate (PSPR) by 67.8 % and 81.8 %, respectively. During long-term cycling at 4C, the peak temperature (PT) and maximum temperature difference (MTD) of batteries in the module incorporating PEE@EBF were reduced by 11.8 °C and 4 °C, respectively, compared to natural convection cooling. In addition, the heat generated during the battery thermal runaway was efficiently absorbed and transferred by PEE@EBF, delaying the irreversible thermal runaway process by 633 s. This indicated that the sandwich-type PEE@EBF was suitable for thermal management and fire protection in lithium-ion batteries or energy storage devices.

Synergistic Reinforcing Effect of Hazelnut Shells and Hydrotalcite on Properties of Rigid Polyurethane Foam Composites.

Recently, the development of composite materials from agricultural and forestry waste has become an attractive area of research. The use of bio-waste is beneficial for economic and environmental reasons, adapting it to cost effectiveness and environmental sustainability. In the presented study, the possibility of using hazelnut shell (HS) and hydrotalcite (HT) mineral filler was investigated. The effects of fillers in the amount of 10 wt.% on selected properties of polyurethane composites, such as rheological properties (dynamic viscosity, processing times), mechanical properties (compressive strength, flexural strength, hardness), insulating properties (thermal conductivity), and flame-retardant properties (e.g., ignition time, limiting oxygen index, peak heat release), were investigated. Polyurethane foams containing fillers have been shown to have better performance properties compared to unmodified polyurethane foams. For example, the addition of 10 wt% of hydrotalcite filler leads to PU composite foams with improved compression strength (improvement by ~20%), higher flexural strength (increase of ~38%), and comparable thermal conductivity (0.03055 W m-1 K-1 at 20 °C). Moreover, the incorporation of organic fillers has a positive effect on the fire resistance of PU materials. For example, the results from the cone calorimeter test showed that the incorporation of 10 wt% of hydrotalcite filler significantly reduced the peak of the heat release rate (pHRR) by ca. 30% compared with that of unmodified PU foam, and increased the value of the limiting oxygen index from 19.8% to 21.7%.

Surface layer reinforcement modification for wood with high strength and flame retardancy performances

The high-value utilization of low-value wood can effectively address the shortage of wood resource, while also contributing to the global green sustainable development and the implementation of “dual carbon” strategy. The present study employed an innovative technology to achieve controllable surface reinforcement modification of fast-growing poplar wood, resulting in improved strength and exceptional flame retardancy for structural applications. The achievement was realized through a three-step method, involving delignification, impregnation, and surface densification, while minimizing the loss of wood volume. The results demonstrated that surface functional densification can significantly improve the mechanical properties of fast-growing poplar wood, with the modulus of rupture (MOR) and modulus of elasticity (MOE) reaching 140.6 MPa and 11.8 GPa, respectively, representing a 3.4-fold and 2.5-fold increase compared to the control group (CK). The samples were found to possess thin surface-densified layers, while the core layer remained unaltered, thereby exhibiting a sandwich structure with significant disparity in density between the layers, reaching up to a factor of 2. The pores structure of the surface layers underwent significant densification, with a gradual deformation distributed throughout its thickness direction. A process optimized for surface densification involving a 2-hour delignification duration and a pressure of 3 MPa. The sample subjected to surface functional modification exhibited a 90-second delay in the peak of heat release compared with the CK. The heat release rate (HRR) experienced a significant deceleration, accompanied by notable reductions in total heat release (THR) and smoke production rate (SPR). The mechanisms underlying the enhancement of surface functionality were elucidated from the perspectives of physical mechanics, microstructure, and flame retardancy, providing a theoretical foundation for the efficient utilization of fast-growing wood.

Functionalized LDH via intercalation of gluconate anion and surface assembly of ultrafine copper hydroxide for improving mechanical properties and the fire safety of epoxy resin

To impart epoxy resin (EP) with outstanding mechanical properties and fire safety, LDH was systematically functionalized through gluconate anion (GA) intercalation followed by surface assembly of ultrafine Cu(OH)2, resulting in the LDH-GA@Cu(OH)2 hybrid. Comprehensive characterizations confirmed the successful synthesis of the desired product, with a uniform distribution of ultrafine Cu(OH)2 nanoparticles on the GA-intercalated LDH surface. The findings revealed that LDH-GA@Cu(OH)2 improved the mechanical properties of EP due to the increased LDH layer spacing, facilitating EP chain insertion, and the hydrogen bonding between the –OH of GA and the EP matrix. Fire retardancy tests indicated that the EP composite containing 7.5 wt% LDH-GA@Cu(OH)2 achieved a limiting oxygen index (LOI) of 30.1%. Furthermore, compared to pure EP, the composite demonstrated significant reductions in the peak heat release rate (PHRR) and peak CO production rate (PCOP) by 47.4% and 60.5%, respectively, underscoring its superior flame-retardant and toxic smoke suppression capabilities. Mechanistic studies further indicated that ultrafine Cu(OH)2 enhanced char formation through catalytic charring at the interface, which promoted compact and cohesive char layers. Overall, this work proposes a promising functionalization strategy for LDH to endow EP with excellent comprehensive performance.

Design of experiments optimized OMEx-diesel blends on a heavy-duty engine − Part 1: Combustion and emissions analysis with EGR and injection timing variation

Oxymethylene dimethyl ether (OME) as a renewable E-fuel provides huge potential for simultaneous soot and NOx reduction on heavy-duty engines, but a thorough optimization of combustion and emission characteristics of great interest to achieve that potential. To achieve that goal, diesel-oxymethylene dimethyl ethers (OMEx) blends are investigated on a single-cylinder heavy-duty research engine with different operating strategies using the design of experiments (DOE) method. A representative truck cruising condition with engine speed of 1425 RPM and 30 % load was targeted, because of the relatively high particulate matter (PM) emissions with regular B7 diesel. In general, the required injection duration at a fixed load increases with OMEx addition related to its reduced lower heating value, hence limiting the available energy before the decreased ignition delay, and resulting in a reduced premixed heat release peak. The ignition delay becomes shorter with increasing OMEx content due to its higher reactivity. Because of the higher reactivity of OMEx and higher oxygen content leading to a lower stoichiometric air–fuel ratio, the burn duration is inversely proportional to OMEx addition at this relatively low-load condition, and seemingly independent of injection duration. Subsequently, the combustion phasing (CA50, the crank angle where 50 % of the heat has been released) is advanced with increasing OMEx. In addition to combustion analysis, the particle number concentration is measured using an engine exhaust particle sizer. To obtain good consistency with the well-established AVL smoke meter results an appropriate particle mass density array of EEPS needed to be adopted. Using the DOE approach methodology, a response surface of PM emissions based on the experimental data indicates that the soot emissions strongly correlate to OMEx content in the blends, satisfying EU VI regulations without after treatment when OMEx content surpasses 17 % at this highway cruising condition on the research engine. While OMEx concentration has a slightly negative effect on NOx, these emissions can be significantly reduced with increasing exhaust gas recirculation (EGR) ratios. On the contrary, CO and unburned hydrocarbon are effectively reduced with OMEx addition. Finally, a comprehensive global emissions map indicates that OMEx has the potential to disrupt the traditional soot-NOx trade-off relationship compared to diesel. Based on this map at the studied condition, the engine can comply with the emission regulations when OMEx- and EGR- ratio are above 24.1 % and 37.2 % respectively, with an injection timing of 10.5 CAD bTDC.

Facile preparation of heptazine-covered Fe2O3 and its synergistic effect on the enhanced flame retardance of silicone rubber composite

The flammability of silicone rubber (SR) significantly limits its broad use in areas that require high flame retardancy. In this study, heptazine-covered Fe2O3, which exhibits effective flame retardancy, was prepared using simple ball milling and heat treatment, which are advantageous for large-scale production. The prepared filler was incorporated into SR. The addition of 7.02 wt% FM filler increased the thermal degradation onset temperature at 5 % weight loss from 492.5 °C for neat SR to 502.7 °C (FM 1:1 composite). Moreover, the peak heat release rate and peak smoke production rate of the FM 1:1 composite significantly decreased by 43.15 % and 68.42 %, respectively, indicating a significant enhancement in the fire safety and smoke suppression of the FM composites. The chemical, morphological, and electronic structures of the FM fillers, pyrolysis gas production, and char residue were thoroughly investigated to reveal the possible flame-retarding mechanisms of the SR composites.

Flame Retardancy and Thermal Stability of Rigid Polyurethane Foams Filled with Walnut Shells and Mineral Fillers.

Recently, the influence of the concept of environmental sustainability has increased, which includes environmentally friendly measures related to reducing the consumption of petrochemical fuels and converting post-production feedstocks into raw materials for the synthesis of polymeric materials, the addition of which would improve the performance of the final product. In this regard, the development of bio-based polyurethane foams can be carried out by, among other things, modifying polyurethane foams with vegetable or waste fillers. This paper investigates the possibility of using walnut shells (WS) and the mineral fillers vermiculite (V) and perlite (P) as a flame retardant to increase fire safety and thermal stability at higher temperatures. The effects of the fillers in amounts of 10 wt.% on selected properties of the polyurethane composites, such as rheological properties (dynamic viscosity and processing times), mechanical properties (compressive strength, flexural strength, and hardness), insulating properties (thermal conductivity), and flame retardant properties (e.g., ignition time, limiting oxygen index, and peak heat release) were investigated. It has been shown that polyurethane foams containing fillers have better performance properties compared to unmodified polyurethane foams.

Optimization Design of the Multidimensional Heterostructure toward Lightweight, Broadband, Highly Efficient, and Flame-Retarding Electromagnetic Wave-Absorbing Composites.

A novel multidimensional electromagnetic wave-absorbing material was developed by combining carboxylated carbon nanotubes (CNT) with graphene oxide (GO) through multidimensional design, and cobalt/nickel-based metal organic frameworks (Co/Ni-MOF) were subsequently loaded onto the GO surface via its rich functional groups to form the composite absorbing material CNT-rGO-Co/Ni-MOF. Incorporating 25 wt % of CNT-rGO-Co/Ni-MOF into the paraffin matrix led to a remarkable RLmin value of -43 dB at 16.4 GHz, with an effective absorbing bandwidth (EAB) exceeding 4 GHz, all within a thickness of just 1.5 mm, showcasing its "lightweight, broadband, and high efficiency" characteristics. The exceptional electromagnetic wave absorption performance was attributed to multi-interface polarization loss, resistance loss, and magnetic medium loss. Furthermore, when incorporating 10 wt % of CNT-rGO-Co/Ni-MOF, the heat release capacity and peak heat release rate of EP/CNT-rGO-Co/Ni-MOF10 decreased by 59.2 and 52.6%, respectively.

Fully biobased approach for sustainable flame retardancy, antibacterial and anti-UV modification of silk fabric

The versatile modification of silk fabric using a fully biobased approach is intriguing. In this study, phytic acid and vanillin, which are plant extracts, were utilized to synthesize reactive vanillin phytate ester for modifying silk fabric to achieve durable flame retardancy, antibacterial and anti-UV performance. The multifunctional properties, thermal resistance, smoke and heat suppression capacity, flame-retardant durability and mechanism of modified silk fabrics were investigated. The vanillin phytate ester imparted high antimicrobial and UV resistance to silk fabric, achieving a 97 % inhibition rate against Escherichia coli and reaching an “excellent” level of UV protection. The modified silk fabric also possessed the self-extinguishing capacity, with a limiting oxygen index value as high as 33.5 %. There was also a significant reduction of 71.7 % in peak heat release and 40 % in smoke release compared with those of the original silk. After undergoing 20 washing cycles, the modified silk fabrics also self-extinguished and passed the vertical burning test, and such good washing resistance was achieved by the Schiff base cross-linking of vanillin phytate ester on the silk fabric. An intumescent flame-retardant mechanism was also identified by char residue analyses, which was driven by the synergistic charring action of phosphate groups and aromatic structures.

Tannic acid coated ammonium polyphosphate: For flame retardant and UV resistant of polypropylene

Polypropylene (PP) has the advantages of excellent mechanical properties and easy molding, but its shortcomings such as high flammability and poor ultraviolet (UV) resistance cannot be ignored. In this paper, APP was used as the core, 1, 10-diamino-decane (DA) was used as a "bridge" to connect TA to the surface of APP, obtaining TAPP through oxidation self-polymerization. The addition of TAPP greatly improved the flame retardancy and UV resistance of PP matrix. The limiting oxygen index of the PP/22.5 %TAPP sample was increased to 31.0 %, and it was able to pass the UL-94 V-0 rating without droplet produced. Compared with PP samples, the peak heat release rate and peak smoke release rate of PP/22.5 %TAPP sample were reduced by 65.0 % and 44.7 %, respectively. In addition, the tensile strength and impact strength of PP/22.5 %TAPP samples decreased by only 2.7 % and 15.0 % after 60 h UV irradiation. The results showed that the addition of TAPP effectively improved the flame retardancy and UV aging resistance of PP. This study provides a feasible method for the preparation of anti-UV aging and flame-retardant PP composites.

Radially and Axially Oriented Ammonium Alginate Aerogels Modified with Clay/Tannic Acid and Crosslinked with Glutaraldehyde.

Lightweight materials that combine high mechanical strength, insulation, and fire resistance are of great interest to many industries. This work explores the properties of environmentally friendly alginate aerogel composites as potential sustainable alternatives to petroleum-based materials. This study analyzes the effects of two additives (tannic acid and montmorillonite clay), the orientation that results during casting, and the crosslinking of the biopolymer with glutaraldehyde on the properties of the aerogel composites. The prepared aerogels exhibited high porosities between 90% and 97% and densities in the range of 0.059-0.191 g/cm3. Crosslinking increased the density and resulted in excellent performance under loading conditions. In combination with axial orientation, Young's modulus and yield strength reached values as high as 305 MPa·cm3/g and 7 MPa·cm3/g, respectively. Moreover, the alginate-based aerogels exhibited very low thermal conductivities, ranging from 0.038 W/m·K to 0.053 W/m·K. Compared to pristine alginate, the aerogel composites' thermal degradation rate decreased substantially, enhancing thermal stability. Although glutaraldehyde promoted combustion, the non-crosslinked aerogel composites demonstrated high fire resistance. No flame was observed in these samples under cone calorimeter radiation, and a minuscule peak of heat release of 21 kW/m2 was emitted as a result of their highly efficient graphitization and fire suppression. The combination of properties of these bio-based aerogels demonstrates their potential as substituents for their fossil-based counterparts.

Sustainable furfuryl alcohol-based flame retardants with regular spherical morphology: Endow polypropylene with excellent flame retardancy, smoke suppression, and mechanical properties

Preparation of polyolefins possessing superior flame retardant and mechanical properties has always been a hot research topic. Herein, a novel high-performance flame retardant was designed and prepared to address the dilemma between flame retardancy and mechanical properties. Through self-stabilized precipitation polymerization of furfuryl alcohol (FA) and maleic anhydride (Ma), followed by successive amination and phosphorylation treatment, bio-based phosphorylated FMa microspheres (P-FMa) were successfully obtained. Benefiting from strong synergistic effect between P-FMa and ammonium polyphosphate (APP), the polypropylene (PP)/APP/P-FMa composites exhibited excellent flame retardant and smoke suppression properties. At a dosage of only 19 wt% APP/P-FMa, the PP/APP/P-FMa reached UL-94 V-0 rating and a limiting oxygen index of 32.2 %, and the peak heat release rate and peak smoke production rate decreased by 76.1 % and 52.6 % compared with neat PP, respectively, due to the formation of denser and firmer char layer. Notably, the tensile strength of PP/APP/P-FMa maintained at a high level of 43.2 MPa. More importantly, the impact strength reached 10.5 kJ/m2, increase by 138.6 % compared to PP/APP, mainly attributed to improved dispersion and compatibility between APP/P-FMa and PP matrix. Owing to its ability to simultaneously improve flame retardant and mechanical properties, P-FMa possesses great potiential as a high-performance flame-retardant filler.

The effect of water mist nozzle settings on fire suppression of electric vehicles in garages

In recent years, along with the widespread use of electric vehicles (EV), EV fires have occurred frequently. However, few studies have investigated EV fires in confined spaces. To address this gap, this paper aims to explore the different aspects of fire evolution of EVs as well as examining the suppression effect of different water mist (WM) settings on these fires. Multiple simulations are carried out, using the Fire Dynamics Simulator (FDS) simulation tool, considering different numbers and working pressures of WM devices. The results highlighted that the number of WM devices had a more significant effect on the fire. Peak heat release was reduced by 17 % and peak arrival time was delayed by 26 % using 6 MPa with 3 nozzles compared to 0 nozzles. Additionally, it leads to accelerated mixing of the smoke layer with the air layer. Moreover, it was shown that the closer to the fire source in the vertical direction, the greater the degree of peak temperature decrease. In this regard, the maximum reduction in the measured temperature was around 70 %.