Preparation of Polyurea Elastomer with Flame Retardant, Insulation and Thermal Conductivity Properties

By using 6,6-((sulfonylbis(4,1-phenylene)bis(azanediyl))bis(thiophen-2-ylm-ethylene))bis6H-di-benzo[c,e][1,2]oxaphosphinine 6-oxide(DOPO-N)as phosphorus-nitrogen flame retardant,the polyurea(PUA)with flame retardant properties(PUA/DOPO-N)was prepared.In addition,organically modified montmorillonite(OMMT)and magnesium hydroxide(MH)were used as co-effectors respectively,and the flame retardant PUA(PUA/DOPO-N/OMMT and PUA/DOPO-N/MH)were also prepared.Thermal properties,flame retardant properties,flame retardant mechanism and mechanical properties of PUA/DOPO-N,PUA/DOPO-N/OMMT and PUA/DOPO-N/MH were investigated by thermogravimetric(TG)analysis,limiting oxygen index(LOI),UL 94,cone calorimeter test,scanning electron microscopy(SEM),and tensile test.The results show that the LOI value of PUA/20%DOPO-N,PUA/18%DOPO-N/2%OMMT and PUA/15%DOPO-N/5%MH are 27.1%,27.7%,and 28.3%,respectively,and UL 94 V-0 rating is attained.Compared with PUA,the peak heat release rate(pk-HRR),total heat release(THR)and average effective heat combustion(av-EHC)of PUA/20%DOPO-N,PUA/18%DOPO-N/2%OMMT and PUA/15%DOPO-N/5%MH decrease significantly.SEM results indicate that the residual chars of PUA/20%DOPO-N,PUA/18%DOPO-N/2%OMMT and PUA/15%DOPO-N/5%MH are completer and more compact.The complex of DOPO-N/OMMT and DOPO-N/MH have synergistic flame retardancy.The mechanical properties of PUA can be improved by the addition of DOPO-N,DOPO-N/OMMT and DOPO-N/MH,respectively.The insulation performance test shows that the volume resistivity of PUA/20%DOPO-N is 6.25×10^(16)Ω.cm.Furthermore,by using modified boron nitride(MBN)as heat dissipating material,the complex of PUA/MBN was prepared,and the thermal conductivity of PUA/MBN was investigated.The thermal conductivity of PUA/8%MBN complex coating at room temperature is 0.166 W/(M·K),which is a 163%improvement over pure PUA.

Synthesis of Organic-Inorganic Hybrid Aluminum Hypophosphite Microspheres Flame Retardant and Its Flame Retardant Research on Thermoplastic Polyurethane

Aluminum hypophosphite microspheres(AHP) were synthesized by hydrothermal method using NaH2PO2·H2O and AlCl3·6H2O as raw materials, and then the AHP microspheres were polymerized by surface polymerization of micro-nanospheres with cyclic cross-linked poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol)(PZS). A new organic-inorganic poly(phosphonitrile)-modified aluminum hypophosphite microspheres(PZS-AHP) were synthesized by encapsulation and applied to flame retardant thermoplastic polyurethane(TPU). The microstructure and chemical composition of the PZS-AHP microsphere were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray spectroscopy. The thermal stability of PZS-AHP microsphere was explored with thermogravimetric analysis. Thermogravimetric data indicate that the PZS-AHP microspheres have excellent thermal stability. The thermal and flame-retarding properties of the TPU composites were evaluated by thermogravimetric(TG), limited oxygen index tests(LOI), and cone calorimeter test(CCT). The TPU composite achieved vertical burning(UL-94) V-0 grade and LOI value reached 29.2% when 10 wt% PZS-AHP was incorporated. Compared with those of pure TPU, the peak heat release rate(pHRR) and total heat release(THR) of TPU/10%PZS-AHP decreased by 82.2% and 42.5%, respectively. The results of CCT indicated that PZS-AHP microsphere could improve the flame retardancy of TPU composites.

Research Progress in Flame Retardant in Flame Retardant Coatings

Flame retardant coatings are functional materials that can serve as decorative and protec-tive substrates in the event of a fire.Flame retardant coatings generally consist of two parts:a base material and a flame retardant agent.A detailed introduction was given to the development of flame retardant coatings in recent years and the flame retardants used in flame retardant coatings.Flame retardants mainly include halogen flame retar-dants,phosphorus nitrogen flame retardants,expansion flame retardants,biomass flame retardants,and graphene flame retardants.The application of flame retardant coatings in the fields of epoxy resin,polyurethane,etc.was elaborated.In addition,the application of new biomass flame retardants and graphene flame retardants was introduced,and the future development of flame retardant coatings and flame retardants was described.

Superior and safer lithium sulfur batteries realized by robust polysulfides-retarding dam with high flame retardance

The unparalleled energy density has granted lithium-sulfur batteries(LSBs)with attractive usages.Unfortunately,LSBs still face some unsurpassed challenges in industrialization,with polysulfides shuttling,dendrite growth and thermal hazard as the major problems triggering the cycling instability and low safety.With the merit of convenience,the method of designing functional separator has been adapted.Concretely,the carbon aerogel confined with CoS_(2)(CoS_(2)-NCA)is constructed and coated on Celgard separator surface,acquiring CoS_(2)-NCA modified separator(CoS_(2)-NCA@C),which holds the promoted electrolyte affinity and flame retardance.As revealed,CoS_(2)-NCA@C cell gives a high discharge capacity 1536.9 mAh/g at 1st cycle,much higher than that of Celgard cell(987.1 mAh/g).Moreover,the thermal runaway triggering time is dramatically prolonged by 777.4 min,corroborating the promoted thermal safety of cell.Noticeably,the higher coulombic efficiency stability and lower overpotential jointly confirm the efficacy of CoS_(2)-NCA@C in suppressing the lithium dendrite growth.Overall,this work can provide useful inspirations for designing functional separator,coping with the vexing issues of LSBs.

Thermal Runaway of Lithium-Ion Batteries Employing Flame-Retardant Fluorinated Electrolytes

Fluorinated electrolytes possess good antioxidant capacity that provides high compatibility to high-voltage cathode and flame retardance;thus,they are considered as a promising solution for advanced lithium-ion batteries carrying both high-energy density and high safety.Moreover,the fluorinated electrolytes are widely used to form stable electrolyte interphase,due to their chemical reactivity with lithiated graphite or lithium.However,the influence of this reactivity on the thermal safety of batteries is seldom discussed.Herein,we demonstrate that the flame-retardant fluorinated electrolytes help to reduce the flammability,while the lithium-ion batteries with flame-retardant fluorinated electrolytes still undergo thermal runaway and disclose their different thermal runaway pathway from that of battery with conventional electrolyte.The reduction in fluorinated components(e.g.,LiPF 6 and fluoroethylene carbonate(FEC))by fully lithiated graphite accounts for a significant heat release during battery thermal runaway.The 13%of total heat is sufficient to trigger the chain reactions during battery thermal runaway.This study deepens the understanding of the thermal runaway mechanism of lithium-ion batteries employing flame-retardant fluorinated electrolytes,providing guidance on the concept of electrolyte design for safer lithium-ion batteries.

Pyrolysis Mechanism of a Cyclotriphosphazene-Based Flame-Retardant Epoxy Resin by ReaxFF Molecular Dynamics

Cyclotriphosphazene derivatives can effectively improve the flame retardancy and fire safety of epoxy resins(EPs)via their influence on the pyrolysis process.In this work,the effects of hexa(5-methyl-2-pyridinoxyl)cyclotriphosphazene(HMPOP)incorporation on the initial pyrolysis of an EP at 500–3500 K were studied using the ReaxFF method.The pyrolysis fragments,initial reaction pathways,and main products were identified for the EP and EP/HMPOP composites.The activation energies were derived by fitting the weight percentage curves for solid species during the pyrolysis reactions and the obtained values were in good agreement with experimental data.The initial EP pyrolysis reactions included four major decomposition modes,which primarily involved the cleavage of C–O and C–N bonds.The main pyrolysis products were H_(2)O,CO,C_(2)H_(4),and CH_(2)O.HMPOP bonded with the oxygen-containing fragments to form larger molecular fragments and reduced the amounts of C_(0)–C_(4) products,especially that of the harmful gas CH_(2)O.Thus,HMPOP promoted the formation of carbon clusters and reduced the generation of combustible gases,ultimately decreasing the capacity for fire propagation.

A novel high-efficient P/N/Si-containing APP-based flame retardant with a silane coupling agent in its molecular structure for epoxy resin

A flame retardant containing multiple antiflaming elements usually exhibits high-efficient flame retardancy. Here, a novel P/N/Si-containing ammonium polyphosphate derivative(APTES-APP) is synthesized from ammonium polyphosphate(APP) and silane coupling agent(3-aminopropyl)triethoxysilane(APTES)via cation exchange, which is quite different in the chemical structure from APTES-modified APP for retaining silicon hydroxyls. APTES-APP is highly efficient for the epoxy resin. 8%(mass) APTES-APP imparts excellent flame retardancy to the epoxy resin, with a V-0 rating at the UL-94 test(1.6 mm)and an LOI value of 26%(vol). The peak heat release rate and total smoke production of the flameretardant epoxy resin are decreased by 68.1% and 31.3%, respectively. The synergy of P/N/Si contributes to the well-expanded char residue with a strong and dense surface layer, which is a very good barrier against heat and mass transfer. Besides, there is no significant deterioration in the mechanical properties of flame-retardant epoxy resin thanks to silicon hydroxyls forming hydrogen bonds with epoxy molecules. Meanwhile, other molecules can be grafted onto APTES-APP via these silicon hydroxyls, if needed.Briefly, this work has developed a new strategy for amino silane as flame retardants. In conjunction with a low-cost and simple preparation method, APTES-APP has a promising prospect in the high-performance flame-retardant epoxy.

Regulating the Localization of Intumescent Flame Retardant for Improving the Flame Retardancy of Ethylene-vinyl Acetate Copolymer Using Polyamide 6 as a Charring Agent

Polyamide 6 (PA6) was employed as a charring agent of intumescent flame retardant (IFR) to improve the flame retardancy of ethylene-vinyl acetate copolymer (EVA). Different processing procedures were used to regulate the localization of IFR in the EVA matrix. Localizations in which IFR was dispersed in the PA6phase or in the EVA phase were prepared. The effect of the localization of IFR on the flame retardancy of EVA was investigated. The limited oxygen index (LOI), vertical burning (UL 94) and cone calorimeter test (CCT)showed that the localization of IFR in the EVA matrix exhibited a remarkable influence on the flame retardancy.Compared with EVA/IFR, a weak improvement in the flame retardancy was observed in the EVA/PA6/IFR blend withthe localization of IFR in the PA6 phase. When IFR was regulated from the PA6 phase to the EVA matrix,a remarkable increase in the flame retardancy was exhibited. The LOI was increased from 27.8%to 32.7%, and the UL 94 vertical rating was increased from V-2 to V-0. Moreover, an approximately 41.36%decrease in the peak heat release rate was exhibited. A continuous and compact intumescent charring layer that formed in the blends with the localization of IFR in the EVA matrix should be responsible for its excellent flame retardancy.

Synthesis and thermal stability of a novel phosphorus-nitrogen containing intumescent flame retardant

包含膨胀火焰的新奇的磷氮延迟蚂蚁(P N IFR ) 与 N-methylaniline 经由 dichloropentate 的反应被准备。产品的结构被 1H NMR， 31P NMR， MS 和红外证实。TGA 分析证明它有有效热稳定性。

Study on the Flame-retardant Properties of High Flame-retardant Acrylic Fiber Knitted Fabrics

This paper involved five kinds of weft-knitted fabrics made from high flame-retardant acrylic/cotton(0/100,30/70,50/50,70/30,100/0).The article adopted the vertical burning method,limiting oxygen index method and Cone Calorimeter test method for testing fabric flame retardant property.By comparison with these five fabrics,the effects on the properties of high flame-retardant acrylic fiber knitted fabrics due to the content of high flame-retardant acrylic fiber were analyzed.

Synthesis and Structure of A Novel Caged Bicyclic Phosphate Flame Retardant

PI novel caged bicyclic phosphate flame retardant tri(1-oxo-2,6,7-trioxa-1-phosphabicyclo [2.2.2] octane-methyl) phosphate (Trimer) was synthesized from 1-oxo-4-hydroxymethyl-2,6,7-trioxa-1-phosphabicyclo [2.2.2] octane (PEPA) and phosphorus oxychloride in this paper. Its structure was characterized by elemental analysis. FTIR, H-1 NMR. P-31 NMR and X-ray diffraction analysis.

Levels and distribution of brominated flame retardants in the soil of Harbin in China

This study reports the presence of brominated flame retardants in the topsoil in and around Harbin, a city in northeastern China. Samples of soil were collected from 17 locations in 2006, and the levels of 9 polybrominated diphenylethers （PBDEs 17, 28, 47, 66, 99, 100, 153, 154, and 183） ranged from 2.45 to 55.9 pg/g dry weight （dw） with a mean of 26.3 pg/g dw. These levels are very low comparing with those for some cities in Europe and USA. BDE 209 and hexabromocyclododecane were the two dominant congeners, with mean concentrations of 520 pg/g dw and 1750 pg/g dw, respectively. The concentrations of the total nine PBDE congeners clearly decreased from urban areas to background, but the compositions of individual congeners differed. Proportions of heavier congeners decreased while those of lighter congeners increased, along urban-rural-background transect, providing evidence for an urban fractionation effect. Correlation analysis indicated similar sources for PBDEs, hexabromocyclododecane, and 1,2-bis（2,4,6-tribromophenoxy）-ethane from urban areas but pentabromoethylbenzene was probably present due to long-range atmospheric transport. Principal component analysis was used to determine the characteristics of the relationships among these brominated flame retardants in the field.

Synthesis and Application of Novel Triazine-Based Charring-Foaming Agents in Intumescent Flame Retardant Polypropylene

Three novel triazine-based charring-foaming agents (M2-CFA,M4-CFA,and M6-CFA) were synthesized successfully with only water as the solvent and were characterized by FT-IR and thermal gravimetric analysis (TGA).These three charring-foaming agents and the byproduct 944-by were employed to study the effectiveness of the novel intumescent flame retardant dopant on the fire retardancy of polypropylene (PP) investigated through UL-94 and limiting oxygen index (LOI) tests.TGA results showed that the M4-CFA presented good char formation ability (char residue: 26.8% at 700 ℃).It was found that the sample with a 2/1 mass ratio of APP to M4-CFA exhibited the best flame retardancy among all the PP composites: 35.5% LOI and a V-0 rating of UL-94.Additionally,the microstructure and morphology of char residues were further studied by XRD,Raman spectroscopy and SEM.

Microencapsulated ammonium polyphosphate by polyurethane with segment of dipentaerythritol and its application in flame retardant polypropylene

Dipentaerythritol(DPER),4,40-diphenylmethanediisocyanate(MDI)and melamine(MEL)are used as raw materials to microencapsulate ammonium polyphosphate(MAPP)in situ polymerization.The MAPP is characterized by Fourier transform infrared(FT-IR),scanning electron microscopy(SEM),transmission electron microscopy(TEM)and thermal gravimetric analysis(TGA).The results show that the coating operation can effectively improve water resistance of ammonium polyphosphate(APP),and MAPP has higher residual rate than that of APP after combustion.The flame retardant action of MAPP and APP in polypropylene(PP)is investigated by the limited oxygen index(LOI),vertical burning test(UL-94),TGA,SEM,and cone calorimeter test(CCT).The LOI value of the PP/MAPP composite at the same loading is higher than that of PP/APP composite.UL 94 ratings of PP/MAPP composites are raised to V-0 at 20 wt%loading.The results of CCT also show that MAPP is more efficient than APP.The morphological structures observed by digital photos and SEM demonstrated that MAPP could be promoted to form the continuous and compact intumescent char layer.The flame retardant mechanism of PP/MAPP is also discussed.

STUDIES ON FLAME-RETARDANT PC/ABS MULTIPLE-ELEMENT ALLOY

The preparation technology of flame-retardant PC/ABS alloys was studied in this paper. Using a high-efficiency flame retardant system and by means of multiple-ingredient compatibilizing, PC/ABS alloys with excellent impact strength and flame retardant property were prepared. The experimental results showed that by using PS-g-MAH and SMA as synergistic compatibilizers, the notched Izod impact strength and flammability of PC/ABS alloy obtained in the present work can be up to 175 J/m and UL-94 VO, respectively.

Effect of Flame Retardant Containing Phosphorus and Silicone on Thermal Performance of PC/ABS

A flame retardant （DPA-SiN） containing phosphorus, nitrogen and silicon elements was synthesized. The halogen free flame retardant was incorporated into PC/ABS to improve its flame retardancy. The flame-retardant properties of the PC/ABS/DPA-SiN blends were estimated by limiting oxygen index （LOI） values and CONE Calorimeter, while thermal stabilities were investi- gated through thermo gvavimetric analysis （TGA）. The PC/ABS/DPA-SiN blends were thermally degraded at 400℃ for different amounts of time and studied by Fourier transform infrared spectroscopy （FTIR） to better understand the degradation behavior of PC/ABS/DPA-SiN.

A NEW SYNERGIST FOR INTUMESCENT FLAME RETARDANT POLYPROPYLENE

The synergistic effects of silicotungstic acid (SiW12) as a catalyst in the phosphorus-nitrogen compounds AM-based intumescent flame-retardant (IFR) polypropylene (PP) were studied using the limiting oxygen index (LOI), the UL-94 test, thermogravimetric analysis (TGA), real time Fourier transform infrared (FTIR), laser Raman spectroscopy (LRS). The LOI data show that SiW12 added to PP/IFR systems has a synergistic FR effect with an IFR additive named AM. The TGA data show that SiW12 apparently increases the thermal stability of the PP/IFR systems at high temperature (T > 500degreesC). The FTIR results provide the positive evidence that IFR can improve the thermal stability of PP and SiW12 can induce a higher rate of formation of phosphoric acid and its derivatives. The LRS measurements provide useful information on the carbonaceous microstructures. In short, a suitable amount of SiW12 (1.5 wt%) exerts synergistic effects with the IFR by increasing the LOI value and the thermal stability at high temperature and promoting the formation of charred structures on the burning PP surface.

Preparation and characterization of tung oil-based flame retardant polyols

Three kinds of tung oil-based structural flame retardants polyols(TOFPs) were prepared by new methods in this paper. First, tung oil was used to produce monoglyceride and diglyceride by transesterification with glycerol by sodium methoxide. The products after transesterification were epoxidized by peracetic acid which was in-situ generated from acetic acid and hydrogen peroxide in the presence of sulfuric acid catalyst. And then, TOFPs were prepared from epoxidized alcoholysis tung oil(EGTO) with 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO), diethyl phosphate(DEP) and diethanolamine(DEA) by ring-opening reactions, respectively. GPC was used to evaluate the conversion rate, at optimum reaction conditions, selectivity for monoglyceride in transesterification. The influence of different parameters such as temperature, mole ratio or mass ratio on the conversion rate of transesterification and epoxidation were investigated. The molecular structures of TOFPs were characterized by FTIR and ~1HNMR. Finally, tung oil-based polyurethane foams(TOPUFs) were prepared by a one-shot process using TOFPs with polyisocyanate. The LOI values of TOPUFs whose content of DOPO-EGTO,DEP-EGTO and DEA-EGTO were 100 wt% can reach to 26.2%, 25.1%, and 24.4%, respectively.

Synergistic effect of MXene on the flame retardancy and thermal degradation of intumescent flame retardant biodegradable poly(lactic acid)composites

The effect of Ti3C2 MXene nanosheets on the intumescent flame retardant(IFR)poly(lactic acid)(PLA)composites was investigated among a series of PLA/IFR/MXene,which were prepared by melt blending 0-2.0 wt%MXene,10.0 wt%-12.0 wt%IFR and PLA together.The results of limiting oxygen index(LOI)and vertical burning(UL-94)discover that the combination of 0.5 wt%MXene and 11.5 wt%IFR synergistically improves the fire safety of PLA to reach UL-94 V-0 rating with LOI value of 33.0%.The PLA/IFR/MXene composites perform an obvious reduction in peak of heat release rate(HRR)in cone calorimeter tests(CCTs).Furthermore,the carbon residues after CCTs were characterized by scanning electron microscope(SEM),laser Raman spectroscopy(LRS),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).It is demonstrated that both the titanium composition of the MXene structure and the characteristics of the two-dimensional material enhance the PLA/IFR/MXene composite materials’ability to produce a dense barrier layer to resist burnout during thermal degradation.

Comparative study on the flame retardancy of CO_(2) and N_(2) during coal adiabatic oxidation process

To test the effectiveness of N_(2) and CO_(2) in preventing coal from spontaneously combusting,researchers used an adiabatic oxidation apparatus to conduct an experiment with different temperature starting points.Non-adsorbed helium(He)was used as a reference gas,and coal and oxygen concentration temperature variations were analyzed after inerting.The results showed that He had the best cooling effect,N_(2) was second,and CO_(2) was the worst.At 70℃and 110℃,the impact of different gases on reducing oxygen concentration and the cooling effect was the same.However,at the starting temperature of 150℃,CO_(2) was less effective in lowering oxygen concentration at the later stage than He and N_(2).N_(2) and CO_(2) can prolong the flame retardation time of inert gas and reduce oxygen displacement with an initial temperature increase.When the starting temperature is the same,N_(2) injection cools coal samples and replaces oxygen more effectively than CO_(2) injection.The flame retardancy of inert gas is the combined result of the cooling effect of inert gas and the replacement of oxygen.These findings are essential for using inert flame retardant technology in the goaf.