Smoke Density Test Research Articles

Study on Synergistic Flame-Retardancy of Surface Modified Zinc Stannate and Ammonium Polyphosphate on Polypropylene Nanocomposites

The effect of zinc stannate and synergy between zinc stannate with ammonium polyphosphate in polypropylene matrix is studied. The zinc stannate nanoparticles were synthesized by surfactant assisted low temperature precipitation method, and further surface modified with tetraethyl-orthosilicate at room temperature. Zinc stannate (ZS) and ammonium polyphosphate (APP) were incorporated in polypropylene matrix (1, 5 and 10 % by wt.). PP nanocomposites were analysed for flexural strength, tensile strength, linear burning rate, smoke density and LOI test. Morphology of nano particles and composites were analysed by FESEM. Mechanical analysis of PP nanocomposites demonstrates that, the modified ZS-TEOS performed better than unmodified ZS. Smoke density profiles suggest that the APP could slightly generate more smoke in PP with ZS and ZS-TEOS. Linear burning rate test results indicates that the APP with ZS and ZS-TEOS provide stability to PP for resisting flame spread.

Synergistic modification of hydrolyzed keratin-based rigid polyurethane foam with zinc stannate and aluminum hypophosphite to improve its thermal stability and flame retardant properties

Abstract Zinc stannate (ZS) was prepared for flame retardant modified rigid polyurethane foam (RPUF). The flame retardancy and thermal stability performance of the modified RPUFs were investigated by limiting oxygen index (LOI), cone calorimeter (CONE), smoke density (Ds) test and thermogravimetric (TG) differential thermal analyzer. The LOI of RPUF5-7.5 AL/7.5 ZS with 5 wt% hydrolyzed keratin (HK), 7.5 wt% aluminum hypophosphate (AL) and 7.5 wt% ZS increased from 26.1 % to 27.2 %. At 50 kW/m2 radiant intensity, RPUF5-7.5 AL/7.5 ZS had the lowest peak heat release rate (PHRR) and heat release rate (THR), which were 108.17 kW/m2 and 2.56 MJ/m2, respectively. In addition, RPUF5-7.5 AL/7.5 ZS had the highest initial decomposition temperature of 191.24 °C and the largest activation energy (E) of 148.16 kJ/mol. Under flameless condition, the maximum Ds of RPUF5-7.5 AL/7.5 ZS was 31.25, and its light transmittance was also the highest, i.e., 57.89 %. Therefore, ZS/AL was selected as a synergistic flame retardant system to modify the RPUF, and promotes the development of high-performance building materials.

Synthesis of antioxidant functionalized nano-TiO2 for improving fire resistance and UV-shielding behavior of intumescent fire-retardant coatings for cable

A unique hybridized antioxidant named TiO2-KH550-PA, of which silane modified nano-TiO2 particles were grafted with 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid by acylation reaction, was applied to intumescent fire-retardant coatings for cable. Through fire protection test, contact angle test, thermogravimetric test and UV-ageing test, the effects of TiO2-KH550-PA on hydrophobicity, flame retardancy, smoke suppression, anti-ageing and charring performance for coatings were evaluated. The obtained results indicate that the TiO2-KH550-PA can enhance the hydrophobicity of the coating, thereby reducing the adhesion of dust on the coating surface. Additionally, TiO2-KH550-PA has a greatly promoting role in strengthening the fire protection abilities of the coating, but an appropriate amount is the key. Compared to coatings without composite, the intumescent fire-resistant coating for cable containing 1 wt% TiO2-KH550-PA (IFRCC2) exhibits excellent fire protection performance, including a prolongation by 2.6 times in failure time, an increase by 1.7 times in char layer height, and an increase by 0.4 times in light transmittance for smoke density test. Furthermore, the presence of TiO2-KH550-PA can also strengthen the oxidation resistance, charring ability and char layer stability of the coating, when the remaining mass of IFRCC2 increases to 49.0 % at 800 °C. The anti-ageing performance test demonstrates that the TiO2-KH550-PA can absorb ultraviolet light, eliminate free radicals, and raise the structural stability of the coating, thus reinforcing the durability of the fire resistance for the coating.

Enhancing the thermal and mechanical properties of sulfonated peek fiber composites with reduced smoke density and toxicity

AbstractPolyether ether ketone (PEEK) sulfonation process is a reasonably easy but time‐consuming to manufacture composites. This study focuses on altering PEEK powder in a sulfuric acid solution via a sulfonation process to develop sulfonated PEEK (SPEEK) resin for the fiber‐reinforced thermoplastic composite manufacturing and characterization steps. In this study, about 5 wt% PEEK powder was sulfonated in 98% sulfuric acid solution for 12 h at 65°C. The water bath technique was used for the precipitation process to obtain the SPEEK polymer. After proper washing and drying, the SPEEK matrix (resin) was obtained by dissolving it in dimethylformamide in a ratio of 1:2. This resin solution was then used to manufacture thermoplastic Kevlar and glass fiber‐reinforced composites employing wet layup process and cured at an elevated temperature under pressure. These SPEEK composites passed the flame retardancy UL94 test with a V0 rating. The average water contact angle of the glass fiber‐ and Kevlar‐SPEEK composites is 93.67° and 102.24°, respectively. The average tensile strength values of these composites were found 222.22 and 284.35 MPa, correspondingly. The smoke density and toxicity tests of the glass fiber‐SPEEK composite confirmed lower smoke generation with the modifications. These SPEEK‐fiber composites can be considered for various industrial applications, including aviation, energy, drone, defense, and automotive.

Investigation of flame-retardant characteristics of a polyaryl ether containing phthalazinone moiety

The aerospace, automotive and other industries require very safe specialty engineered plastics that can be used for long times at high temperatures and produce few harmful fumes during combustion in the event of a safety accident, which is essential for protecting personal life and property in a confined environment. The twisted noncoplanar structures give poly (phthalazinone ether) resins excellent temperature resistance and solubility, but clarifying the flame retardancies of the resins is the key to broader application. Herein, a comprehensive comparison has been made between poly (phthalazinone ether) resins and the specialty engineered plastic polysulfone (PSF) based on flame resistance. In vertical burning test, the poly (phthalazinone ether) resin showed a very short flame self-extinguishing time (within 1 s), furthermore, the light transmittance of poly (phthalazinone ether) resin was 100 % at 300 s in the smoke density test, whereas, this value was 10 % for PSF. And the thermal decomposition process and flame retardancy mechanism were investigated by microscale combustion calorimetry, scanning electron microscopy, X-ray photoelectron spectroscopy and thermogravimetric-infrared spectra mass spectrometry. The results indicated that the introduction of phthalazinone moiety not only enhanced the glass transition temperature of the polyaryl ether, but also delayed the smoke generation. This work deepens our understanding of the effects of the molecular structure on the flame retardancy of polyaryl ether resins and provides useful guidance for the design and preparation of polyaryl ether resins with excellent comprehensive properties.

A new multifunctional flame-retardant coating for cotton fabric to enhance smoke suppression, and UV shielding properties

Turmeric powder (TP) is used in the textile industry as a colouring agent, but its impact on the flammability properties of textiles wasn’t investigated. In this work, new coatings containing TP and TP with melamine polyphosphate (MPP) were utilized to enhance the thermal stability, flame retardancy, colour strength (K/S), and UV-protection factor (UPF) of cotton fabric (CF). Flammability tests indicated that TP alone failed to prevent flame spread in the fabric, and it increased the emission of toxic gases, especially CO and CO2. In contrast, the MPP/TP coating was able to put an end to the spread of a flame in CF, and the samples achieved self-extinction. The value of the limiting oxygen index (LOI) of CF was 18.2%, and it enhanced in MPP/TP containing samples to be 37.8%. K/S and UPF values showed that MPP/TP coatings improved the K/S and UPF values of CF to 2.9 and 290, respectively. Additionally, they lowered the toxic gases produced during CF combustion and the maximum specific optical density (Dsmax) of CF. The new coatings improved the char residue production in treated samples at 750 °C compared to CF, according to the thermogravimetric analysis (TGA) data. Untreated and treated samples' mechanical and physical characteristics were measured and compared. Analysis of smoke toxic gases and inspection of char remained following the smoke density test revealed that MPP/TP coating enhanced the flame retardancy of CF in both the condensed and gas phases.

Hierarchical NiO/Al2O3 nanostructure for highly effective smoke and toxic gases suppression of polymer Materials: Experimental and theoretical investigation

There is still a lack of in-depth investigation of the suppression mechanism for polymeric materials. Herein, based on the density functional theory (DFT) study, the flame retardancy, smoke, and toxic gases suppression mechanisms of hierarchical NiO/Al2O3 nanostructures in thermoplastic polyurethane (TPU) are in-depth revealed. The incorporation of NiO/Al2O3-S into TPU leads to a significant reduction in total smoke release by 41.9%, and peak CO production rate by 47.8% (Cone calorimetry test results). Besides, the NiO/Al2O3-S results in a remarkable decrease of 48% in Dsmax during the smoke density test. Most importantly, based on DFT calculations, incorporating catalysts enhances the adsorption energy of CO, O2, and CO2 on the surface of TPU nanocomposites, thereby facilitating CO oxidation reactions. This is conducive to reducing flue gas emissions and toxicity levels. This work introduces DFT into the flame retardancy research of polymer materials, thus providing reliable guidance for designing highly effective smoke suppressants.

Fire-retardant acrylic coating by silica -coated limestone (SCL) microencapsulation

ABSTRACT Silica-coated limestone (SCL) microcapsule was synthesized and successfully introduced into acrylic resin to produce fire-retardant coatings. SCL microcapsules were prepared by encapsulating limestone granules with silica nanoparticles using epoxy resin as a binder. The morphology and the chemical composition of the SCL microcapsules were confirmed by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The performance of SCL microcapsules on mechanical, flame retardant and thermal stability of the coatings was thoroughly investigated using FTIR, SEM, thermogravimetric analysis (TG), smoke density test, adhesion pull-off test, pendulum damping test and cone calorimeter test. The results shows that while the adhesion strength, pendulum hardness and limiting oxygen index (LOI) increased remarkably, the values of flame spread ratings (FSR), specific optical density (ODs), heat release rate (HRR), total heat release rate(THRR), smoke production rate (SPR) and total smoke production rate (SPR) decreased significantly with the introduction of SCL microcapsules. The TGA results confirm that incorporation of SCL microcapsules increases the thermal stability and boosts formation of large char layers.

Effect of polycarbonate‐polydimethylsiloxane block copolymer and two commercial toughening agents on the flame retardancy and smoke emission of rigid polyvinyl chloride

AbstractIn this work, different test methods were used to investigate the flame retardancy and smoke emission of polyvinyl chloride (PVC) toughened with polycarbonate‐polydimethylsiloxane block copolymer (PC‐b‐PDMS) and two other commercial toughening agents. The oxygen index result and heat release curves in the cone calorimetry test showed that toughened PVC has reduced flame retardancy compared to unmodified PVC. However, the vertical combustion test showed that all samples have achieved the highest flame retardant rating, indicating that the flame resistance of these toughened PVC is still adequate for use. In terms of smoke emission, the results of the cone calorimetry test and the smoke density test showed a significant difference. In the smoke density test, it was found that PVC toughened with PC‐b‐PDMS has less smoke generation in the early stage of combustion. In the cone calorimetry test, the total smoke production was lower for PVC and significantly higher for toughened PVC. This difference was mainly due to the different test conditions of these two tests.

Construction of layered double hydroxide composites derived from tungsten tailing particles for simultaneously enhancing fire protection and anti-ageing properties of intumescent fire-resistant coatings applied in wood surface

Tungsten tailing is a great deal of solid waste produced in the production process of tungsten metal, for which there is no simple and effective treatment method in the world. The success synthesis of layered double hydroxide composites (TTF-LDH) by co-precipitation method from tungsten tailing is a feasible way to solve this problem. The structure and properties of TTF-LDH were confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The obtained TTF-LDH was in combination with intumescent flame retardants (IFR) to achieve a series of intumescent fire resistance coatings. The effects of TTF-LDH on the fire protection, smoke suppression and anti-ageing performances of coatings were evaluated by fire resistance test, smoke density test, cone calorimeter test and accelerated ageing test, while the flame-retardant mechanism of TTF-LDH in coatings was revealed. The results illustrate that an appropriate amount of TTF-LDH can remarkably enhance smoke suppression and fire-resistant abilities of coatings, among which the coating containing 3 wt % TTF-LDH (IFRC-LDH3) exhibits the optimal synergistic effect, revealing a smoke density rating value of 17.3%, a total heat release of 7.0 MJ/m2 and an equilibrium backside temperature of 146.2 °C at 900 s. Meanwhile, the addition of TTF-LDH can strengthen the char formation and thermal stability abilities of the coatings, and the residual weight of IFRC-LDH3 rises to 35.7% at 800 °C, as supported by thermogravimetric (TG) analysis. The results of accelerated ageing test demonstrate that the presence of TTF-LDH can strengthen structural stability of coating, decrease migration and decomposition of IFR, thus giving the coating better integrity and durability of fire-resistant and smoke suppression properties.

Preparation and properties of modified ammonium polyphosphate synergistic with tris(2-hydroxyethyl) isocynurate for flame-retardant LDPE

Abstract UF-SiAPP was prepared by modifying ammonium polyphosphate with the urea formaldehyde resin (UF), tetraethylorthosilicate (TEOS), and vinyltriethoxysilane (A-151). Moreover, a new intumescent flame retardant (IFR) used for low density polyethylene (LDPE) flame retardant was obtained by mixing UF-SiAPP with tris(2-hydroxyethyl) isocynurate (THEIC). The structure, morphology, and mechanical properties of flame retardants and LDPE composites were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, TG, and universal material testing machines. Furthermore, the flame-retardant properties of LDPE composites were comprehensively investigated by limiting oxygen index (LOI), UL-94, and cone calorimetry tests. The results show that UF-SiAPP exhibits excellent hydrophobic properties and good compatibility with LDPE after being modified by UF, TEOS, and A-151. And the flame-retardant properties of LDPE composites are significantly improved by adding IFR-containing UF-SiAPP. Especially, the LDPE composites attained the LOI value of 30.5% and reached the V-0 level after introducing 20.0 wt% UF-SiAPP and 10.0 wt% THEIC. And the tensile strength reached 13.55 MPa, which was 10.33% higher than that of LDPE/IFR with UF-APP and 13.21% higher than that of LDPE/IFR without THEIC in the same proportion. The smoke density tests demonstrate that the addition of UF-SiAPP not only effectively improves the residual carbon content and thermal stability of LDPE composites but also significantly reduces smoke emissions.

Enhancing anti‐meltdrop and smoke suppression properties of flame retardant poly(ethylene terephthalate) fabric by fiber‐blending method

AbstractFlame retardant poly(ethylene terephthalate) (FRPET) fabrics are widely used in daily life. However, the meltdrop and visible smoke produced during combustion significantly limit its further application. This study proposes a simple but effective method of fiber‐blending to improve the above shortcomings. On the basis of synergistic flame retardancy of nitrogen and phosphorus, the FRPET was blended with flame retardant viscose (FRV) and intrinsic nitrogen‐containing flame retardant fibers (NIFRFs), to prepare the binary and ternary blended FRPET samples labeled as NIFRF/FRPET and FRV/NIFRF/FRPET, respectively. The limiting oxygen index and cone calorimeter test show that the ternary‐blending could effectively suppress the combustion of FRPET fiber composite. The smoke density test and UL‐94 vertical combustion test indicate that ternary‐blending could better improve the meltdrop characteristics and smoke suppression property than binary‐blending. Among all samples, FRV/PMIA/FRPET (1:4:5) owns the highest LOI of 32.6% and lowest smoke density of 61.37. The investigation of residual char utilizing scanning electron microscopy, the X‐ray photoelectron spectroscopy and the Laser Raman spectroscopy demonstrates that the FRPET meltdrop would adhere to the surface of component fibers to avoid droplets. Besides, fiber‐blending could increase the yield and degree of graphitization of residual char, which is conducive to improving samples' flame retardancy through the condensed phase. This work may provide a workable strategy to expand the application areas of FRPET fabrics.

Smoke suppression, flame retardancy, and fire toxicity of polypropylene containing melamine salt of pentaerythritol phosphate halloysite

AbstractPolypropylene (PP) was melt blended with a new mono molecular intumescent flame retardant, melamine salt of pentaerythritol phosphate halloysite (MPPH) to enhance its thermal stability, flame retardancy, and smoke suppression properties. The structure of MPPH was elucidated by Fourier transform infrared (FTIR), 1H NMR, X‐ray diffraction (XRD), and energy dispersive X‐ray (EDX) analysis. PP composites results showed that MPPH increased the thermal stability of PP at high temperatures in all PP composites. The horizontal flammability test (UL94H) showed that MPPH stopped flame propagation in PP composites. Vertical burning rate test (UL94V) revealed that PP composites can attain V0 rating at loading levels 25, 30, and 35 wt.% of MPPH. Limiting oxygen index (LOI) data indicated that adding 20, 25, 30, and 35 wt.% of MPPH to PP increased the LOI value of PP (19.2%) to 27.1%, 32.5%, 35.4%, and 38.7%. MPPH succeeded in reducing the maximum specific optical density (Dsmax), mass specific optical density (MOD), and rate of smoke generation during the first 4 min (VOF4) of PP composites compared to PP alone. FTIR gas analyzer results revealed that MPPH decreased the emission of CO and CO2 in the gas phase during the combustion process. Digital photos and scanning electron microscope (SEM) images of char residues remained after the smoke density test revealed that MPPH succeeded in forming a cellular and cohesive char layer on the PP surface. The new data is expected to increase the use of PP in rigid packaging applications.

P/N Flame Retardant Based on a Pyrimidine Ring for Improving the Flame Retardancy, Mechanical Properties, and Smoke Suppression of Epoxy Resin

A P/N flame-retardant TBD based on a pyrimidine ring was devised and developed by reacting 2,4,6-triaminopyrimidine, benzaldehyde, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to create a less toxic, low-smoke, and mechanically improved the flame-retardant epoxy resin (EP). The EP modified using TBD exhibited good transparency, which was attributed to the outstanding compatibility of TBD with the EP. With a phosphorus content of only 0.65%, EP/TBD10 passed the V-0 rating of the UL-94 test, and the limited oxygen index increased from 27.1% (pure EP) to 38.1%. In the cone calorimetry test (CCT), the peak heat release rate and the total heat release decreased by 34.9 and 45.7%, respectively, compared to pure EP. In addition, the modified cured EP exhibited good mechanical properties owing to the action of rigid groups and the formation of hydrogen bonds, and the tensile strength and modulus as well as the flexural strength and modulus of the samples were improved. In the smoke density test, EP/TBD20 received the ratings of HL1 and HL2 in Ds(4) and VOF4, respectively, according to EN45545-2. All results indicate that TBD is an efficient flame retardant that can enhance the flame retardancy and mechanical properties of the curing EP and reduce its smoke density, making it suitable for use in the rail transportation industry.

A novel Ti(OH)4/graphene flame retardant towards reducing fire hazards of phenolic resin

Ti(OH) 4 /graphene was synthesized by hydrolysis of titanium tetrachloride into titanium hydroxide and precipitation on the surface of graphene nanosheets, and was incorporated into phenolic resin to prepare phenolic composites using hexamethylenetetramine as a curing agent. After that, the effects of Ti(OH) 4 /graphene on the thermal stability, flame retardancy, and smoke suppression properties of phenolic matrix were studied. When the content of Ti(OH) 4 /graphene was 5 wt.%, phenolic composites passed the UL-94 V-0 rating with a limiting oxygen index (LOI) of 28.6%, and the residual char at 800 °C was 56.83 wt.%. Cone calorimeter tests demonstrated that the peak heat release rate (pHRR), total heat release (THR) and total smoke production (TSP) of phenolic composite contained 10 wt.% Ti(OH) 4 /graphene were 86.3 kW/m 2 , 30.74 MJ/m 2 and 1.8 m 2 , respectively, which were reduced by 41.85%, 24.82%, and 30.78% compared with pure phenolic resin. And the smoke density test also showed that the smoke density of phenolic composite contained 10 wt.% Ti(OH) 4 /graphene had a 51.89% reduction. These data indicated that Ti(OH) 4 /graphene can effectively improve the flame retardant and smoke suppression performance. Moreover, the char residue after combustion is investigated using SEM, FTIR, XRD and Raman technologies, and the results demonstrated that Ti(OH) 4 /graphene could greatly promote the formation of a continuous and dense char residue layer in phenolic composites. Py-GC/MS results further revealed that the degradation products contents of phenolic resins were decreased by incorporating Ti(OH) 4 /graphene. Therefore, the flame retardancy of phenolic composite is significantly improved through the mechanism of endothermic effect, coverage effect, and dilution effect of combustible gas. This feasible method can provide new insights for reducing fire hazards of phenolic resin. • Ti(OH) 4 /graphene was prepared and incorporated into phenolic resin as an additive flame retardant. • Phenolic composites containing only 5 wt.% Ti(OH) 4 /graphene passed UL-94 V-0 rating. • Ti(OH) 4 /graphene significantly improved flame retardancy performances of phenolic composites. • The flame retardant mechanism of Ti(OH) 4 /graphene in phenolic composites was investigated.

The preparation and property analysis of B4C modified inorganic amorphous aluminum phosphates-based intumescent flame retardant coating

In response to high environmental requirements, an incombustible inorganic intumescent flame retardant coating was prepared from amorphous aluminum phosphate emulsion as the matrix, with boron carbide as the modifier. The influence of boron carbide (B4C)on the fire resistance performance and physic-chemical properties of coatings were studied by means of large panel combustion method, smoke density test, Fourier transformed infra-red analysis (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), specific surface area (BET method) and pore size analysis. With the addition of 0.75 wt% B4C, the backside temperature of APB3 coating (aluminum phosphate-based coating modified with 0.75 wt% B4C) after an hour was only 140 ℃, 33.4 % lower than that of blank APB0 coating. And the smoke density (Ds) of APB3 was only 64.73 %, 36.3 % lower than that of blank APB0. The foaming expansion caused by decomposition reactions, the structural improvement caused by boron carbide oxidation, and the formation of ablative resistant ceramics and glass were the main reasons for excellent flame retardant and thermal insulation performance. Remarkably, the melting B2O3 generated from the oxidation of B4C could repair cracks, modify pore structure, improve the integrity of closed pores, increase the specific surface area of porous structure, and promote the formation of borosilicate glass. Due to the structural integrity of the outermost coating surface caused by the oxidation of B4C and the construction of borosilicate glass, much gas was shielded inside the coating, making the coating more eco-friendly. Besides, APB3 coating has good water resistance. After immersion in water for 360 h, the reduction rate of fire resistance performance of the coating was only 17.1 %. This work provides theoretical guidance for broadening the types of intumescent coatings and promotes the development of inorganic green coatings.

One‐step flame retardant/hydrophobic finishing on cotton fabric with ammonium salt of hexamethylenediamine ‐ N, N, N′, N′ ‐ tetra (methylphosphonic acid) doped silica sol

AbstractWith the rapid development of textile technology, single‐function textile finishing is difficult to meet the current needs of people for textiles. Textiles with flame retardancy, superhydrophobicity, UV resistance, and other functions are increasingly favored by people. At present, most of the preparation processes of multifunctional textiles are complex and time‐consuming. In this work, a flame retardant hexamethylenediamine tetramethylene phosphate ammonium salt of hexamethylenediamine ‐ N, N, N′, N′ ‐ tetra (methylphosphonic acid) (AHDTMPA) was synthesized using hexamethylenediamine tetramethylene phosphate (HDTMPA) and urea with aqueous solution as solvent. Then AHDTMPA and cetyltrimethoxysilane were added into the solution with methyl trimethoxysilane (MTMOS) and tetraethyl orthosilicate (TEOS) as precursors to obtain a multifunctional sol. Finally, the multifunctional cotton fabric can be obtained by immersing the cotton fabric in the multifunctional sol in one‐step. The limiting oxygen index (LOI) and water contact angle (WCA) value of the finished cotton fabric was 27.6% and 131.4°, respectively. The FT‐IR characterization results and the SEM analysis verified the synthesis of AHDTMPA. The micro calorimeter combustion (MCC) and thermo gravimetric (TG) analysis indicated that the finished samples had less heat release capacity and less weight loss. The smoke density test showed good smoke suppression of the finished cotton fabric. Moreover, the whiteness of finished samples was nearly unchanged. In this work, the flame retardant and hydrophobic multi‐functional cotton fabric was prepared by one‐step, and the method is simple and efficient. The prepared functional cotton fabrics can be widely used in home textile fabrics, automotive interior fabrics, clothing fabrics, flags, tents, and protective clothing.

Zn-doped carbon microspheres as synergist in intumescent flame-retardant thermoplastic polyurethane composites: Mechanism of char residues layer regulation

Despite thermoplastic polyurethane (TPU)/ammonium polyphosphate (APP) being an excellent intumescent flame-retardant TPU composite (IFR-TPU), it is still not a "fire-safety" TPU composite. In this work, the Zn-doped carbon microspheres (CMSs-Zn) were prepared and added into the TPU/APP composite as a synergist to fabricate an IFR-TPU composite with excellent fire safety performance (TPU/CMSs-Zn). Cone calorimeter tests exhibited the peak heat release rate (pHRR), total heat release (THR), peak smoke production rate (pSPR), total smoke release (TSR) of TPU/CMSs-Zn composites were decreased by 65.4 %, 50.7 %, 65.3 %, and 63.4 % respectively. Moreover, the smoke density tests showed that the luminous flux (LF) of TPU/CMSs-Zn increased from 1.4 % to 40.1 %. In addition, the investigation of the flame-retardant mechanism for TPU/CMSs-Zn revealed that CMSs-Zn amplifies the role of APP in condensed phase by participating in char formation and catalysis effect, thus forming a dense protective char residues layer. The char residues layer regulation mechanism can provide a novel strategy for facilitating fire-safety TPU composite.

Fabrication of Polypyrrole-Decorated Tungsten Tailing Particles for Reinforcing Flame Retardancy and Ageing Resistance of Intumescent Fire-Resistant Coatings.

Polypyrrole-decorated tungsten tailing particles (PPY-TTF) were prepared via the in situ polymerization of pyrrole in the presence of tungsten tailing particles (TTF), and then carefully characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TG) analyses. The effect of PPY-TTF on the flame retardancy, smoke suppression property and ageing resistance of intumescent fire-resistant coatings was investigated by a fire protection test, smoke density test and cone calorimeter test. The results show that PPY-TTF exerts excellent cooperative effect on enhancing the flame retardancy and smoke suppression properties of the intumescent fire-retardant coatings, which is ascribed to the formation of more cross-linking structures in the condense phase that enhance the compactness and thermal stability of intumescent char. The cooperative effect of PPY-TTF in the coatings depends on its content, and the coating containing 3 wt% PPY-TTF exhibits the best cooperative effect among the samples, showing a 10.7% reduction in mass loss and 35.4% reduction in flame-spread rating compared to that with 3% TTF. The accelerated ageing test shows that the presence of PPY-TTF greatly slows down the blistering and powdering phenomenon of the coatings, thus endowing the coating with the super durability of fire resistance and smoke suppression property. This work provides a new strategy for the resource utilization of tungsten tailing in the field of flame-retardant materials.

A green, durable and effective flame-retardant coating for expandable polystyrene foams

Expandable polystyrene (EPS) foam, one of the most widely used thermal insulation of building materials, is highly flammable, while its traditional flame-retardant coating has been severely restricted by the low efficiency and the use of toxic formaldehyde adhesive. Herein, we demonstrate a formaldehyde-free phosphorus-containing polysiloxane coating that acts as both an adhesive and a flame retardant for EPS foams. In this design, on one hand, the high adhesion of the polysiloxane can evenly and tightly bind the EPS beads and expandable graphite (EG, a flame-retardant synergist filler) at a relatively low additive loading, thus leading to durable thermal insulation even under high humidity conditions. On the other hand, the functional coating can promote the formation of P/Si-containing graphited char layers during the combustion of the EPS composite, which can effectively isolate oxygen, heat, combustible compounds, and smoke particles. As a result, the EPS composite showed excellent flame retardancy with a high limiting oxygen index of 36%, a UL-94V-0 rating, and a significantly reduced peak heat release rate (−76%), while the smoke release can be greatly suppressed both in cone calorimetry and smoke density tests. This work provides a new strategy for the design of environmentally friendly coatings, which can give EPS foam high fire safety and excellent comprehensive performance.