Improved flame retardancy by synergy between cyclotetrasiloxane and phosphaphenanthrene/triazine compounds in epoxy thermoset

A siloxane compound (MVC) and a bi‐group phosphaphenanthrene/triazine compound (TGD) were employed in epoxy thermosets to explore high‐efficiency flame retardant systems. With only 1 wt% MVC and 3 wt% TGD, an epoxy thermoset passed UL 94 V‐0 rating test and achieved a limiting oxygen index value of 34.0%, exhibiting an excellent flame retardant effect. The MVC/TGD system not only decreased the peak value of heat release rate and effective heat of combustion but also imparted an improved charring ability to thermosets, thereby outstandingly reducing the flammability of 1%MVC/3%TGD/EP. Compared with the fire performance of 4%TGD/EP and 4%MVC/EP, the MVC/TGD system showed an obvious flame retardant synergistic effect, mainly depending on the general improvement of flame inhibition, charring and barrier effects of the thermoset during combustion. Evolved gas analysis combined with condensed‐phase pyrolysis product analysis jointly revealed the details of the changed pyrolysis mode. © 2017 Society of Chemical Industry     

Effect of zinc oxide on properties of phenolic foams/halogen‐free flame retardant system

A halogen‐free flame retardant system consisting of ammonium polyphosphate (APP) as an acid source, blowing agent, pentaerythritol (PER) as a carbonific agent and zinc oxide (ZnO) as a synergistic agent, was used in this work to enhance flame retardancy of phenolic foams. ZnO was incorporated into flame retardant formulation at different concentrations to investigate the flammability of flame retardant composite phenolic foams (FRCPFs). The synergistic effects of ZnO on FRCPFs were evaluated by limited oxygen index (LOI), thermogravimetric analysis (TGA), cone calorimeter tests, and images of residues. Results showed that the flame retardant significantly increased the LOI of FRCPFs. Compared with PF, heat release rate (HRR), total heat release (THR), effective heat of combustion (EHC), production or yield of carbon monoxide (COP or COY) and Oxygen consumption (O₂C) of FRCPFs all remarkably decreased. However specific extinction area (SEA) and total smoke release (TSR) significantly increased, which agreed with the gas‐phase flame retardancy mechanism of the flame retardant system. The results indicated that FRCPFs have excellent fire‐retardant performance and less smoke release. And the bending and compression strength were decreased gradually with the increase of ZnO. The comprehensive properties of FRCPFs were better when the amount of ZnO was 1～1.5%. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42730.     

Unsteady combustion processes in a channel with gas stream swirling and its termination

Results of numerical simulation of the flow and combustion of a pre-mixed gas mixture in a cylindrical channel at sudden swirliing of the flow and its sudden termination are considered. The calculations conducted show that the flow swirling allows flame localization in a given volume of the combustion chamber and is an effective method for combustion control. Translated fromFizika Goreniya i Vzryva, Vol. 35, No. 4, pp. 33–40, July–August 1999.     

Flame retardation and thermal stability of novel phosphoramide/expandable graphite in rigid polyurethane foam

A novel flame retardant named diethylene N,N',N''‐tri (diethoxy)phosphoramide (DTP) was synthesized using diethyl phosphate and diethylenetriamine via Atherton–Todd reaction. Then, series of flame‐retardant water‐blown rigid polyurethane foams (RPUFs) with expandable graphite (EG) and DTP were prepared through box‐foaming. The results of thermogravimetric analysis showed that DTP/EG changed thermal degradation process of RPUF and promoted enhancing char residues. The complex flame‐retardant system (EG/DTP) endowed RPUF higher limiting oxygen index (LOI) values (29.1%–30.2%) and lower heat release rate peak (PHRR) values according to LOI and microscale combustion calorimeter tests. More importantly, the synergistic flame‐retardant effect between EG and DTP in RPUF was proved by the analysis of synergistic effectivity values. Based on the analysis of cone calorimetric tests, EG/DTP revealed remarkable effects to inhibit the fire intensity and smoke release of RPUF with decreased PHRR and total smoke production due to good char‐forming action. To further investigate the char‐residues of the foams after combustion, scanning electron microscope and energy dispersive X‐ray spectroscopy analyses were conducted. The results suggested that EG/DTP flame‐retardant system promoted RPUF forming a compact, continuous and phosphorus‐rich char layer as a good fire barrier in combustion. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46434.     

多层阻燃织物整体热防护性能初探

研究了消防服用多层阻燃织物复合系统的整体热防护性及外层织物的阻燃性。将阻燃织物国产间位芳纶、杜邦NomexⅢ和芳纶3A面料与国产间位芳纶毡和阻燃棉布组合,模拟构成消防服的多层织物结构,通过垂直燃烧实验测试分析了阻燃外层织物的阻燃性能,通过热辐射和热对流综合热防护性能(TPP)实验测试分析了多层复合织物的整体热防护性能。实验结果表明:整体热防护性能最好的是国产间位芳纶织物、面密度200 g/m2的芳纶毡和阻燃棉布的组合,但最适宜用于消防服的是NomexⅢ织物、面密度200 g/m2的芳纶毡和阻燃棉布。     

阻燃抗静电改性聚丙烯复合材料性能研究

基于阻燃剂ANTI?660及抗静电剂单苷酸甘油酯（Gm）制备了聚丙烯（PP）复合材料,采用水平垂直燃烧测试仪、氧指数测试仪、表面电阻测定仪、万能试验机和摆锤式冲击试验机等研究了阻燃剂和抗静电剂对复合材料阻燃性能、抗静电性能和力学性能的影响。结果表明,在阻燃剂含量为18.0 %（质量分数,下同）,抗静电剂含量为2.0 %时,复合材料的极限氧指数（LOI）达到26.0 %,UL 94测试达到V?0级,表面电阻下降到1.7×10¹² Ω;添加阻燃抗静电体系的复合材料相比于添加纯阻燃剂的复合材料整体力学性能改变不明显,但仍具有较好的综合力学性能。     

Reducing the flammability of ultra-high-molecular-weight polyethylene by triphenyl phosphate additives

The thermal degradation and combustion of ultra-high-molecular-weight polyethylene (UHMWPE) doped with triphenyl phosphate (TPP) at atmospheric pressure was studied by molecular beam mass spectrometry, dynamic mass spectrometric thermal analysis, microthermocouples, thermogravimetry, gas chromatography/mass spectrometry. The kinetics of thermal degradation of pure UHMWPE and that mixed with TPP at high (≈150 K/s) and low (0.17 K/s) heating rates was investigated. The effective values of the rate constant and activation energy of the thermal degradation reaction were determined. Burning velocity and temperature profiles in UHMWPE and UHMWPE + TPP flames were measured. The composition of the combustion products in a flame zone adjacent to the burning surface of the sample was determined. TPP vapor in the flame was detected. The addition of TPP to UHMWPE was found to reduce the flammability of the polymer. It is shown that TPP acts as a fire retardant in both the condensed and gas phases.     

Wildfire propagation: A two-dimensional multiphase approach

This paper describes a multiphase approach to determining the rate of propagation of a line fire through a randomly packed fuel bed of thermally thin cellulose particles and the induced hydrodynamics inside and above the litter. A set of time-dependent balance equations is solved for each phase (a gas phase andN solid phases) and the coupling between the gas phase and the solid phases is rendered through exchange terms of mass due to thermal degradation of the fuel material (heating, drying, pyrolysis, and char combustion), momentum, and energy. The radiative transfer equation for the fuel bed is deduced from the P1-approximation, and radiation from the flame to the fuel bed is accounted for using the empirical model of Markstein. The kinetics is incorporated to describe pyrolysis and combustion processes. Solution is performed numerically by a finite-volume method. The development of a line fire from the moment of initiation to quasisteady propagation is predicted and discussed. Results obtained by this multiphase model are compared to measurements made on laboratory fires using dead pine needles as fuel. The predicted rates of fire spread for some configurations, including slope effects, agree well with measured values. Translated fromFizika Goreniya i Vzryva, Vol. 34, No. 2, pp. 26–38, March–April, 1998.     

Addition flame‐retardant effect of nonreactive phosphonate and expandable graphite in rigid polyurethane foams

A series of flame‐retardant rigid polyurethane foams (RPUFs) containing nonreactive phosphonate (5‐ethyl‐2‐methyl‐1,3,2‐dioxaphosphorinan‐5‐yl) methyl dimethyl phosphonate P‐oxide (EMD) and expandable graphite (EG) were prepared by water blown. The flame‐retardant properties and mechanism of EMD/EG on RPUFs were systematically investigated. The EMD/EG system effectively increased the limiting oxygen index (LOI) value and decreased the values of total heat release (THR), av‐effective heat of combustion (EHC), pk‐heat release rate (HRR), total smoke release (TSR) of RPUFs. The impact values of LOI, THR, and av‐EHC resulted by EMD/EG system are nearly equal to the sum of the impact values by EMD and EG individually in RPUFs, which implies the addition flame‐retardant effect from EMD and EG. EMD alone exerted excellent gas‐phase flame‐retardant effect by releasing PO fragments with quenching effect. The firm residue produced by EMD combined well with the loose and worm‐like expanded graphite from EG further to form compact and expanded char layer, which brought excellent barrier effect and filtration effect to matrix. That's why pk‐HRR and TSR values of RPUF reduced. Depending on the simultaneous actions of EMD/EG system in gas phase and condensed phase during combustion, the flame‐retardant effects from nonreactive phosphonate and EG on RPUFs were added together. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45960.     

Flame propagation through the header of an in-line flame arrester

This paper reports results of testing a pilot model of a flame arrester for flashback and burnout. The results are treated using the unsteady model of filtration gas combustion. It is shown that the process of burnout of the flame arrester consists of three stages with comparable characteristic times: the stage of flame entry into the porous bed, the stage of flame propagation through it, and the stage of flame exit from the porous bed. The mechanisms operating in each of the stages are described, and the determining parameters are established. Ways of improving the flame arrester performance are studied by theoretical analysis of the burnout process. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 4, pp. 23–38, July–August, 2007.     

Preparation of a chitosan‐based flame‐retardant synergist and its application in flame‐retardant polypropylene

A novel flame‐retardant synergist, chitosan/urea compound based phosphonic acid melamine salt (HUMCS), was synthesized and characterized by Fourier transform infrared spectroscopy and ³¹P‐NMR. Subsequently, HUMCS was added to a fire‐retardant polypropylene (PP) compound containing an intumescent flame‐retardant (IFR) system to improve its flame‐retardant properties. The PP/IFR/HUMCS composites were characterized by limiting oxygen index (LOI) tests, vertical burning tests (UL‐94 tests), microscale combustion calorimetry tests, and thermogravimetric analysis to study the combustion behavior and thermal stability. The addition of 3 wt % HUMCS increased the LOI from 31.4 to 33.0. The addition of HUMCS at a low additive amount reduced the peak heat‐release rate, total heat release, and heat‐release capacity obviously. Furthermore, scanning electron micrographs of char residues revealed that HUMCS could prevent the IFR–PP composites from forming a dense and compact multicell char, which could effectively protect the substrate material from combusting. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40845.     

Synergistic Flame Retardant Effect of Organic Phosphorus–Nitrogen and Inorganic Boron Flame Retardant on Polyethylene

In this study, to develop an organic/inorganic synergistic flame retardant, organic phosphorus–nitrogen flame retardant 6,6-(((sulfonylbis(4,1-phenylene)) bis(azanediyl))bis(thiophen-2-ylmethylene))bis(6H-dibenzo[c,e][1,2]oxaphosphinine 6-oxide (DOPO-N) and inorganic boron flame retardant zinc borate (ZB) were selected. The flame retardant properties of polyethylene (PE) containing ZB/DOPO-N were investigated. PE/20%ZB/10%DOPO-N had better thermal stability and flame retardant properties. The limiting oxygen index of PE/20%ZB/10%DOPO-N reached 24.6%, and UL 94 V-0 rating was attained. The peak heat release rate, total heat release, average effective heat combustion, and fire growth index of PE/20%ZB/10%DOPO-N were lower than when ZB and DOPO-N were added separately. In addition, the flame retardant mechanism was investigated using scanning electron microscopy, X-ray diffraction, energy dispersive X-ray, and Fourier transform infrared spectroscopy. ZB/DOPO-N simultaneously exerted condensed phase and gas phase flame retardant effect. POLYM. ENG. SCI., 60: 414–422, 2019. © 2019 Society of Plastics Engineers     

Flame spread over a liquid surface in a channel of finite section under oncoming air-flow conditions

The propagation of a combustion wave over a shallow hot liquid (n-butanol) blown over by an air flow was studied experimentally. The flame spread was accompanied by pulsations, whose amplitude depended on the oncoming gas velocity. Dependences of the average flame speed on temperature and oncoming gas velocity were obtained. The average speed was found to be independent of the liquid depth ahead of the flame within the experimental error. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 1, pp. 29–34, January–February, 2008.     

Phosphorylated sodium alginate/APP/DPER intumescent flame retardant used for polypropylene

Flame-retardant polypropylene (FR-PP) materials are realized by use of natural-sourced flame-retardant materials. Phosphorylated sodium alginate, ammonium polyphosphate, and dipentaerythritol are used to create an intumescent flame retardant (IFR). This realized flame retardant is embedded into polypropylene (PP) through melt blending method. The components, chemical structures, thermal properties, and degradation mechanisms of the samples are characterized by infrared spectrometry, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, and cone calorimeter test. The results indicate that an effective IFR is obtained due to gas phase and condensed phase synergistic flame-retardant ability during combustion and degradation of FR-PP. This work presents a facile method for preparing FR-PP with efficient flame retardancy. This study is a first proof of concept for an innovative flame retardant, which could find application in future in the fields of automotive industry and the construction of electronic devices. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47794.     

Joint flame‐retardant effect of triazine‐rich and triazine/phosphaphenanthrene compounds on epoxy resin thermoset

To obtain a more efficient flame‐retardant system, the extra‐triazine‐rich compound melamine cyanurate (MCA) was coworked with tri(3‐9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide‐2‐hydroxypropan‐1‐yl)?1,3,5‐triazine‐2,4,6‐trione (TGIC–DOPO) in epoxy thermosets; these were composed of diglycidyl ether of bisphenol A (DGEBA) epoxy resin and 4,4′‐diaminodiphenyl methane (DDM). The flame‐retardant properties were investigated by limited oxygen index measurement, vertical burning testing, and cone calorimeter testing. In contrast to the DGEBA/DDM (EP for short) thermoset with a single TGIC–DOPO, a better flame retardancy was obtained with TGIC–DOPO/MCA/EP. The 3% TGIC–DOPO/2% MCA/EP thermoset showed a lower peak heat‐release rate value, a lower effective heat of combustion value, fewer total smoke products, and lower total yields of carbon monoxide and carbon dioxide in comparison with 3% TGIC–DOPO/EP. The results reveal that MCA and TGIC–DOPO worked jointly in flame‐retardant thermosets. The dilution effect of MCA, the quenching effect of TGIC–DOPO, and their joint action inhibited the combustion intensity and imposed a better flame‐retardant effect in the gas phase. The 3% TGIC–DOPO/2% MCA/EP thermoset also exhibited an increased residue yield, and more compositions with triazine rings were locked in the residues; this implied that MCA/TGIC–DOPO worked jointly in the condensed phase and promoted thermoset charring. The results reveal the better flame‐retardant effect of the MCA/TGIC–DOPO system in the condensed phase. Therefore, the joint incorporation of MCA and TGIC–DOPO into the EP thermosets increased the flame‐retardant effects in both the condensed and gas phases during combustion. This implied that the adjustment to the group ratio in the flame‐retardant group system endowed the EP thermoset with better flame retardancy. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43241.     

木材阻燃研究及发展趋势

近年,随着我国阻燃法规的建立健全,阻燃技术的不断发展,新型的木材阻燃剂及阻燃技术不断涌现。阐述了木材的化学组成及燃烧过程、木材阻燃剂类型、阻燃机理、木材阻燃处理方法及各种处理方法的优缺点,同时介绍了国内外木材阻燃研究的发展方向,对我国木材阻燃剂工业进一步发展提出了建议。木材阻燃的发展趋势是开发一剂多效的新型复合阻燃剂,同时深入探索阻燃机理,为组合新的阻燃体系提供有效的途径,使木材阻燃研究与市场实际需求相结合,为生产实践的应用提供了理论基础。     

陶瓷化组合物对WF／PP复合材料阻燃性能影响的研究

探索了一种聚丙烯木塑复合材料高效无毒、环境友好、价格便宜的阻燃方法。通过向其中添加无机硅酸盐与有机硅橡胶组合物加工成复合材料,使其在燃烧时表面形成陶瓷结构起到防火隔热的作用,从而提高材料的阻燃性能。采用垂直燃烧测试、氧指数测试、锥形量热测试、扫描电镜和热重分析等一系列研究手段,对复合材料燃烧前后的性能与结构进行比较分析。结果表明,陶瓷化组合物的添加可以提高聚丙烯木塑复合材料的阻燃效率,延缓热降解过程,有效地抑制热释放速率和烟释放量以及可燃气体的逸出。     

The dynamic flammability and toxicity of magnesium hydroxide filled intumescent fire retardant polypropylene

The flammability properties of an intumescent fire retardant polypropylene added with magnesium hydroxide was discussed in this study. To evaluate the flammability of the material, limit oxygen index, smoke emission, tensile strength, and our exploitation dynamic flammability evaluation system, tests were assessed in experiments. The results showed that the intumescent flame retardant ammonium polyphosphate-filled polypropylene has superior flammability properties but higher carbon oxide (CO) concentration and smoke density. By adding some magnesium hydroxide additives in intumescent fire retarded polypropylene, the smoke density and CO concentration decrease; and the compound also has superior fire properties. It is concluded that intumescent system and magnesium hydroxide additives are effective on improving combustion properties for polypropylene. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:989–995, 1998     

Spin gas combustion in a narrow slot

Combustion in a gap between two thin circular plates with point injection of the gas in the center is experimentally examined. The existence of several combustion regimes is demonstrated. Unstable pulsed combustion is observed in the case of high flow rates. As the flow rate decreases, a transition to spin combustion occurs under certain conditions. If the distance between the plates is sufficiently small, the so-called excess-enthalpy flame can be realized in an expanding gas flow. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 3, pp. 23–26, May–June, 2006.     

Gap effect on the initiation of detonation in gas mixtures in cylindrical combustion chambers. II. Triggering of detonation within a turbulent flame

Schlieren moving-picture photography is used to study the burnup of oxygen gaseous mixtures in a cylindrical chamber with a gap at its periphery. It is found that a flame penetrating from the chamber into the gap can accelerate up to detonation speeds. The reaction wave in the gap precedes the primary combustion front propagating through the chamber and the reaction products escaping the gap create secondary combustion sources in the chamber. A process occurs in which a detonation wave that appears in the gap near one flank of the flame enters the main volume through the opposite flank, first triggering an explosion in the turbulent combustion zone (“an explosion within an explosion”) and then a detonation wave in the unreacted gas charge (“knock” in an engine). An interpretation is provided for the gas-dynamic structure of the secondary combustion source which is created in the cylindrical combustion chamber by a detonation wave propagating in the gap. Translated fromFizika Goreniya i Vzryva, Vol. 34, No. 4, pp. 77–87, July–August 1998