硝仿肼及其推进剂的研究进展

综述了20世纪90年代以来国外关于高能氧化剂硝仿肼及硝仿肼基新型固体推进剂研究的新进展。介绍了硝仿肼的合成方法、物理化学性能、晶体结构及不同结晶技术对硝仿肼形态及稳定性的影响。通过对硝仿肼爆炸性能及热安定性参数的分析,证实了其作为高能氧化剂的优异性能。通过HNF／Al／GAP、AP／Al／HTPB两种推进剂性能的对比分析,显示出硝肪肼及其推进剂的潜在价值。     

Chemical reactions in the low-temperature zone of a laminar rich propane—air flame

The mechanism of chemical reactions in the low-temperature zone of a rich propane—air flame is considered. It is shown that at temperatures of 300–700 K, intense chemical reactions proceed with the formation of end products and that the water concentration reaches an intermediate equilibrium value even at a temperature of 685 K. In this zone of the front, the diffusion of atomic hydrogen from the high-temperature zone plays a determining role and water is formed mainly by the reactions H + O₂ + M ⇒ HO₂ + M, HO₂ + HO₂ ⇒ H₂O₂ + O₂, H₂O₂ (+M) ⇒ 2OH (+M), C₃H₈ + OH ⇒ C₃H₇ + H₂O. Propane reacts with active centers more effectively than molecular hydrogen. Its primary reactions are due to the interaction with OH and HO₂ radicals. Arguments are given in favor of the thermal-diffusion nature of the superadiabatic temperature phenomenon in rich propane—air flames. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 5, pp. 14–19, September–October, 2006.     

Experimental and numerical methods for studying the flame structure

Laminar premixed flames under laboratory conditions often at reduced pressures are of great interest for combustion chemistry and environmental pollution. Recently, there has been considerable progress in studying the combustion of hydrocarbons, oxygenates, and their mixtures. Methods of laser diagnostics, including cavity ring-down spectroscopy and laser induced fluorescence, combined with a number of mass spectrometry techniques for in situ studies of flames allow measurements of concentrations of major species and intermediate products in flames. The structure of fuel molecules and the effect of fuel composition on the structure of intermediate products were studied from the viewpoint of formation of undesired and potentially harmful combustion products in hydrocarbon and oxygenate flames. Chemiluminescence was studied using data on collisional energy transfer. Low-temperature combustion of strongly diluted mixtures in a flow type reactor was investigated. __________ Translated from Fizika Goreniya i Vzryva, Vol. 45, No. 4, pp. 5–21, July–August, 2009.     

Production of nanoparticles of MgO, BAO, and A12O3 in a premixed flame and its relation to the flame structure

Formation of nanoparticles of magnesium, barium, and aluminum oxides in a fuel-lean oxy-acetylene flame is studied by means of flame sampling. The size distributions and concentrations of particles are measured in various areas of the flame. Possible reaction paths are considered. MgO and BaO nanoparticles are demonstrated to form in the reaction zone where there is a high concentration of radicals. Formation of Al₂O₃ particles is hindered by the reaction AlO + AlO₂ → Al₂O₃ being termolecular. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 6, pp. 25–32, November–December, 2006.     

有机阻燃剂最新进展

论述９０年代卤系阻燃剂领域内的关注热点和卤系、磷系、卤－磷系及膨胀型阻燃剂在近几年内的发展动态。     

RDX flame structure at atmospheric pressure

The chemical structure of an RDX flame at a pressure of 1 atm was studied using probing molecular beam mass spectrometry. The flame was found to contain RDX vapor, and its concentration profile was measured in a narrow zone adjacent to the burning surface. In addition to RDX vapor, ten more species were identified (H₂, H₂O, HCN, N₂, CO, CH₂O, NO, N₂O, CO₂ and NO₂), and their concentration profiles were measured. Two main chemical-reaction zones were found in the RDX flame. In the first, narrow, zone 0.15 mm wide adjacent to the burning surface, decomposition of RDX vapor and the reaction of NO₂, N₂O, and CH₂O with the formation of HCN and NO occur. In the second, wide, zone 0.85 mm wide, HCN is oxidized by NO to form the final combustion products. The composition of the final combustion products was analyzed from an energetic point of view. The measured composition of the products near the burning surface was used to determine the global reaction of RDX gasification at a pressure of 1 atm. Values of heat release in the condensed-phase calculated by the global gasification reaction and by the equation of heat balance on the burning surface (using data of microthermocouple measurements) were analyzed and compared. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 1, pp. 49–62, January–February, 2008.     

含硅三笼状磷酸酯阻燃剂的合成及结构表征

以乙烯基三氯硅烷和1-氧代-4-羟甲基-2,6,7-三氧杂-1-磷杂双环[2,2,2]辛烷(PEPA)为原料,合成含硅三笼状磷酸酯阻燃剂,即三(1-氧代-2,6,7-三氧杂-1-磷杂双环[2,2,2]辛烷-4-亚甲氧基)乙烯基硅烷(EPSi),通过核磁共振光谱、红外光谱、热失重分析等手段对其进行结构表征和热性能分析。结果表明:合成的产物为目标产物EPSi;EPSi在空气和氮气中热分解5%的温度分别为309℃和349℃,700℃残余质量率分别为36.9%和54.5%,具有良好的热稳定性和成炭率。     

膨胀型阻燃剂在橡胶中的应用

介绍了膨胀型阻燃剂的组成及功能改进,总结了膨胀型阻燃剂在天然橡胶、三元乙丙橡胶、丁苯橡胶及氯丁橡胶中的应用进展,并对膨胀型阻燃剂的发展方向做了展望。     

无卤阻燃剂的研究现状

综述了磷系阻燃剂、氮系阻燃剂、硅系阻燃剂、金属氢氧化物阻燃剂及膨胀型阻燃剂的研究状况及阻燃机理。     

Promotion and inhibition of a hydrogen—oxygen flame by the addition of trimethyl phosphate

This paper gives results of numerical modeling of a laminar hydrogen—oxygen flame doped with trimethyl phosphate at various pressures and compositions of the combustible mixture. The calculations were performed using the PREMIX and CHEMKIN-II software packages. It was found that phosphorus-containing additives promoted the flame at subatmospheric pressures and inhibited it at atmospheric pressure. Kinetic analysis showed that catalytic recombination reactions were responsible for both phenomena. In the case of subatmospheric pressures, the promoting effect and its enhancement with increasing additive concentration were related to a flame temperature rise in the chemical-reaction zone due to catalysis of the recombination reactions by phosphorus-containing compounds. Increasing the additive concentration led to an increase in both the rate of the branching reaction H + O₂ = OH + O and the rate of the chain termination reaction, but the increase in branching reaction rate prevails, resulting in an increase in the flame velocity. In the case of atmospheric-pressure flames, where the reaction-zone temperature is close to the adiabatic equilibrium value, the additive led to an increase in the rate of decay of active flame species and, hence, to a decrease in the flame propagation velocity with increasing additive concentration. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 5, pp. 3–13, September–October, 2006.     

Effects of hydrogen addition on flame structure and forced flame response to velocity modulation in a turbulent lean premixed combustor

Flame transfer function measurements were performed in a turbulent premixed lean combustor with various blends of hydrogen and natural gas. The fuel mixture was completely premixed with air upstream of a choked inlet to the combustor to avoid equivalence ratio fluctuations. A variable speed siren was used to modulate fluctuations in the inlet velocity, which was measured using a hot wire anemometer as an input parameter of the flame transfer function. Heat release oscillations as an output function were determined using chemiluminescence measurements from whole flames. Stable flame images were captured to understand general flame behavior over a range of operating conditions and fuel blends. Experimental results showed that the stable flames’ COMs (centers of mass) laid along a common path in a 2-D plane for all of the operating conditions and tested fuel compositions at a given injector geometry, and that variations in the stable flame shape could be characterized by the location of the common path of the flame’s COM. It was also shown that changes in the fuels significantly affected the flame shape; as a result, flame dynamics varied with changes in flame geometry. Accordingly, flames that were close together on the characteristic flame COM curve were shown to have similar forced flame responses.     

无机阻燃剂对PVC/木粉复合材料性能的影响

分别采用A1(OH)3、ZB以及Sb2O3等无机阻燃剂对PVC/木粉复合材料改性,研究不同的阻燃剂配方及阻燃剂含量对PVC/木粉复合材料阻燃性能和力学性能的影响。结果表明:随着A1(OH)3,ZB以及Sb2O3添加量的增加,PVC/木粉复合材料的氧指数(LOI)呈逐渐增大的趋势。Sb2O3阻燃效率最高,当添加量为9份时,氧指数达到35.2%;无机阻燃剂的加入普遍降低了PVC/木粉复合材料的冲击韧性,但对拉伸强度起到了一定的增强作用。     

氯氧化锑阻燃剂研究进展

与Sb2 O3 及NaSb(OH) 6 等锑系阻燃剂比较 ,氯氧化锑阻燃剂具有能大幅度地降低色料用量和显著提高透明度的特点 ,若要将其推向市场 ,关键在于开发新的生产工艺 ,降低生产成本。本文比较了氯氧化锑阻燃剂的各种制造方法 ,综述了氯氧化锑阻燃剂的阻燃机理及其阻燃应用     

Laminar flame speed measurements of dimethyl ether in air at pressures up to 10 atm

Laminar flame speed measurements of dimethyl ether/air mixtures were made at 1, 5, and 10 atm with equivalence ratios ranging from 0.7 to 1.6. All experiments were performed in a large cylindrical constant-volume bomb with optical access. A new method for converting flame images into flame radii was used. Results reported in other studies were investigated, and some explanations on the disparities found are presented. A full uncertainty analysis was performed combining precision errors from data scatter with predicted systematic errors. Uncertainties ranging between 4.2% and 8.6% were found depending on the equivalence ratio and initial pressure. Experimental results agreed well with some other spherical flame experiments and counterflow flame measurements, but were found to be much lower than PIV-based stagnation flame results. Also, two spherical flame studies deviated significantly both in magnitude and trend. Critical radii and Peclet numbers, defined by the onset of rapid flame acceleration, were recorded for all high-pressure experiments. Markstein lengths were measured and showed a decreasing trend with increasing equivalence ratio. Three different methods were used to define the laminar flame thickness, and large disparities were found between them. In this study, the modeled temperature gradient method for the definition of flame thickness is preferred over other methods. Modeling was performed with the latest version of a C3 chemical kinetics mechanism. Good agreement is seen between the experimental results and the model at all pressures. Emphasis is placed in this paper on reporting experimental uncertainties, calculated density ratios, flame temperatures, and flame radii ranges used for data analysis, and the results resolve some discrepancies seen in the literature for dimethyl ether flame speeds.     

Combustion of residual steel gases: laminar flame analysis and turbulent flamelet modeling

In recovery combustion systems operating in the steel industry, energy is provided by boilers burning residual gases of blast furnace and coke oven. To help understand combustion of this particular type of fuels, a numerical study is conducted where the major chemical properties of steel gas flames are collected. The chemical composition of representative fuel and oxidizer steel gas is varied over a large range in calculations using detailed chemistry and complex transport properties. The chemical equilibrium compositions, premixed flame speeds and diffusion flame extinction strain rates are determined. The advantages and shortcomings of the use of vitiated air emerge, and its introduction into the boiler appears as an interesting alternative to reduce NO_x emission. The detailed information obtained with laminar flame calculations is also introduced in flamelet turbulent combustion modeling. Reynolds Averaged Navier Stokes (RANS) simulations of a test case burner are performed and some comparisons between numerical predictions and experimental results are presented.     

无卤本质阻燃热塑性共聚酯

介绍了由9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物二元酸衍生物与对苯二甲酸二羟乙基酯(BHET)或2,6-萘二甲酸二羟乙基酯(BHEN)直接酯化生成的含磷热塑性共聚酯的制备方法及性能。磷的质量分数为0．5％(BHEN共聚酯)或0．75％(BHET共聚酯)时,共聚酯的阻燃性可达UL 94 V-0级,700℃下空气中的成炭率接近20％,且燃烧时产生较少烟雾及有毒和腐蚀性气体。     

HMX flame structure for combustion in air at a pressure of 1 atm

The chemical structure of HMX flame during combustion in air at a pressure of 1 atm was calculated using molecular beam mass spectrometric sampling. HMX vapor was recorded for the first time near the burning surface. A total of 11 species were identified in the HMX flame (H₂, H₂O, HCN, N₂, CO, CH₂O, NO, N₂O, CO₂, NO₂, and HMX vapor), and their concentration profiles were measured. The HMX combustion was unstable. The species concentration profiles exhibit periodic pulsations related to variation in the HMX burning rate. The HMX flame structure at various distances to the burning surface was determined using the average value of the burning rate. Two main zones of chemical reactions in the flame were found. In the first zone ≈0.8 mm wide adjacent to the burning surface, HMX vapor decomposes and NO₂, N₂O, and CH₂O react with each other to form HCN and NO. In the second zone ≈0.8–1.5 mm wide, HCN was oxidized by nitric oxide to form the final combustion products. The composition of the final combustion products was analyzed. The global reaction of HMX gasification at a pressure of 1 atm was established. Heat release values in the condensed phase calculated by the global gasification reaction and by the equation of heat balance on the burning surface (using literature data from microthermocouple measurements) were analyzed and compared. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 6, pp. 26–43, November–December, 2008.     

西欧阻燃塑料工业现状

论述了西欧阻燃塑料工业的现状:一是欧盟各国在建材等行业将实行统一的阻燃性能试验方法和阻燃材料分类标准;二是日益严格的环保法规对阻燃剂的危害性评估结果正挑战阻燃塑料工业;三是新阻燃系统的研发。这些变化将导致西欧阻燃剂及阻燃塑料系统的结构调整。     

原位复合阻燃尼龙6的非等温动力学研究

采用差示扫描量热法研究了原位聚合反应制备阻燃尼龙6的非等温结晶行为,用Jeziorny法和莫志深法对其动力学过程进行了分析。结果表明:由于阻燃剂起到异相成核作用,使晶核的生长变快,提高了阻燃尼龙6的结晶温度和成核速率。随降温速率的增加,其结晶峰从高温向低温方向移动,峰形变宽,结晶时间缩短。同时阻燃剂在尼龙6分子链中存在相互作用力,阻碍了尼龙6分子链在结晶过程中的运动,导致结晶活化能提高,晶体生长速度下降,结晶度降低。     

阻燃剂阻燃机理的探讨

本文介绍了一般阻燃剂主要通过吸热冷却、气相稀释、形成隔热层和终止自由基链反应等途径,来实现对材料的阻燃。同时也相应的阐述了无机阻燃剂、有机阻燃剂以及膨胀型阻燃剂的阻燃特性及机理。