Fabrication and thermal decomposition of glycidyl azide polymer modified nitrocellulose double base propellants

Glycidyl azide polymer(GAP) with the advantages of non-volatility and excellent thermal stability is a candidate as a replacement for nitroglycerine(NG) in a double base propellant. The GAP-NC double base propellants were formulated with GAP and nitrocellulose(NC) fibers. Tensile test and SEM characterization indicated that GAP-NC propellants had a homogeneous structure. Thermogravimetric analysis of GAP-NC propellants revealed that the onset decomposition temperature reached a high level ranging from 192.9 to 194.6 °C, which indicated that the substitution of NG with GAP contributed to the safe storage and process operations for double base propellant. The result analysis of decomposition products of GAP-NC propellants showed that the main gas decomposition products of the propellants were NO, NO_2, CO, CO_2, NH_3, CH_4, HCN, N_2, CH_2O and C_2H_4O. The thermal decomposition process of the specimens was proposed.     

超级铝热剂的制备、表征及其燃烧催化作用

用纳米铝粉和纳米氧化铅、纳米氧化铜和纳米三氧化二铋为原料,采用超声分散复合的方法,制备了纳米超级铝热剂Al/PbO、Al/CuO和Al/Bi₂O₃。采用X射线粉末衍射(XRD)、扫描电镜及能谱分析(SEM-EDS)和红外光谱(IR)对原料和产物的物相、组成、形貌和结构进行分析表征;运用差示扫描量热仪(DSC)评估三种超级铝热剂与双基推进剂主要组分的相容性;研究了3种超级铝热剂对双基推进剂燃烧性能的影响。结果表明,Al/PbO、Al/CuO和Al/Bi₂O₃与推进剂主要组分硝化棉(NC)、硝化棉/硝化甘油(NC/NG)混合物和吉纳(DINA)的相容性均良好,而与黑索今(RDX)和1,3-二甲基-1,3-二苯基脲(C₂)相对较为敏感;含三种纳米超级铝热剂的双基推进剂表现出优异的燃烧性能。     

Thermal characteristics of dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate in contact with nitrocellulose/nitroglycerine under continuous heat flow

Dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50) and nitrocellulose/nitroglycerine (NC/NG) possess good energy properties, which were widely used in propellants, explosives and pyrotechnics. They are easy to contact with each other during their application and storage. However, their thermal characteristics under continuous heat flow have not been reported yet. Therefore, it is of great practical significance to study the thermal properties of TKX-50/NC/NG (mixture of TKX-50 and NC/NG). In this paper, the thermal characteristics and pressure behaviors of TKX-50/NC/NG, TKX-50 and NC/NG were characterized by high pressure differential scanning calorimetry (HPDSC) and adiabatic scanning calorimetry (ASC). The results showed that TKX-50 and NC/NG can promote each other to decompose under continuous heat flow, especially the thermal decomposition which affected by gases generation and heat feedback was more violent in the confined space. The decomposition peak temperature of TKX-50/NC/NG shifted to low temperature when the heat loss was ignored and the removal of decomposition gas was suppressed. The possible decomposition mechanism of TKX-50/NC/NG was speculated. It was considered that the intermediate products of TKX-50 and NC/NG decomposition under thermal stimulation would react with each other, which promoted TKX-50/NC/NG decomposition in one step at lower temperature. Thus, TKX-50 has high reactivity and high potential risk after contact with NC/NG under continuous heat flow. TKX-50 is not suitable for application with NC/NG. This study provides a reference for the structural design of nitrogen rich explosives and further broadens the researchers’ understanding of the application of TKX-50.     

酒石酸铅锆的制备、表征及其燃烧催化作用

以酒石酸、硝酸氧锆和硝酸铅为原料,合成出了双金属盐酒石酸铅锆,采用有机元素分析、X射线荧光光谱和FTIR对其进行了表征。在程序升温条件下,利用TG/DTG、DSC、固相原位反应池/FTIR联用技术,研究了酒石酸铅锆的热行为和热分解机理,描述了酒石酸铅锆的热分解过程,分析得出其最终分解产物为ZrO2、PbO和C。利用螺压工艺制备了含酒石酸铅锆的推进剂样品,研究了酒石酸铅锆对双基系推进剂燃烧性能的影响,分析了其燃烧催化作用。结果表明,酒石酸铅锆对双基系推进剂的燃烧具有良好的催化作用,是一种高效的燃烧催化剂;酒石酸铅锆热分解的最终产物PbO是催化燃烧的主要活性物质,推进剂燃烧过程中形成了氧化铅-铅循环催化体系,而锆和碳则起辅助催化的作用。     

BTATz-Pb复合物对双基和RDX-改性双基推进剂的热行为、非等温动力学及燃烧性能的影响

制备了含3,6-双(1-氢-1,2,3,4-四唑-5-氨基)-1,2,4,5-四嗪(BTATz)铅复合物(LCBTATZ)的双基推进剂和改性双基推进剂. 采用热重-微商热重法(TG-DTG)及差示扫描量热法(DSC)研究了其热分解行为和非等温分解动力学并在此基础上评价了其热安全性. 结果表明, LCBTATz-DB复合物中在350-540 K之间只存在一个放热分解峰, LCBTATz-CMDB复合物中存在两个连续的放热分解峰在390-540 K温度范围内, 其机理方程分别为: f(α)=α^-1/2和f(α)=2(1-α)^3/2. 计算了热加速分解温度(T_SADT)、热爆炸临界温度(T_b)、热点火温度(T_TIT)和绝热至爆时间(t_Tlad),其值分别为: DB001复合物T_SADT=444.50 K, T_TITT=453.96 K, T_b=471.84 K; t_Tlad=39.36 s; CMDB100复合物, T_SADT=442.38 K, T_TITT=452.89 K,T_b=464.13 K,t_Tlad=21.3 s,并以此来评价化合物的热安全性. 考察了LCBTATz-DB以及LCBTATz-CMDB的燃烧性能, 结果表明LCBTATZ 是一种高效的双基燃烧催化剂, 在较大的压力范围内可以显著的提高燃速并且大幅度的降低压力指数. 对于双基推进剂在2-8 MPa压力范围内出现了明显的超燃速现象, 8-12 MPa出现了“麦撒”效应, 对于改性双基推进剂的压力指数降到0.18.     

Effect of pressures on decomposition reaction kinetics of double-base propellant catalyzed with cerium citrate

The decomposition reaction kinetics of the double-base (DB) propellant (No. TG0701) composed of the mixed ester of triethyleneglycol dinitrate (TEGDN) and nitroglycerin (NG) and nitrocellulose (NC) with cerium(III) citrate (CIT-Ce) as a combustion catalyst was investigated by high-pressure differential scanning calorimetry (PDSC) under flowing nitrogen gas conditions. The results show that pressure (2 MPa) can decrease the peak temperature and increase the decomposition heat, and also can change the mechanism function of the exothermal decomposition reaction of the DB gun propellant under 0.1 MPa; CIT-Ce can decrease the apparent activation energy of the DB gun propellant by about 35 kJ mol⁻¹ under low pressure, but it can not display the effect under high pressure; CIT-Ce can not change the decomposition reaction mechanism function under a pressure.     

没食子酸铋锆的制备、表征及其燃烧催化作用

以没食子酸、硝酸铋和硝酸氧锆为原料, 首次合成出了双金属有机盐——没食子酸铋锆, 采用有机元素分析、X射线荧光(XRF)光谱和傅里叶变换红外(FTIR)光谱对其进行了表征. 在程序升温条件下, 利用热重(TG)分析、差示扫描量热法(DSC)、固相原位反应池/FTIR 联用技术, 研究了没食子酸铋锆的热行为和热分解机理,描述了没食子酸铋锆的热分解过程, 分析得出其最终分解产物为Bi₂O₃、ZrO₂和C. 利用螺压工艺制备了含没食子酸铋锆的推进剂样品, 研究了没食子酸铋锆对双基(DB)推进剂燃烧性能的影响, 分析了其燃烧催化作用. 结果表明, 没食子酸铋锆对双基推进剂的燃烧具有良好的催化作用, 是一种高效的燃烧催化剂; 没食子酸铋锆热分解的最终产物是催化燃烧的主要物质, 锆和碳则起辅助催化的作用.     

Thermal decomposition properties of double-base propellant and ammonium perchlorate

The thermal decomposition properties and the heat of combustion (ΔH) of samples with different ammonium perchlorate (AP)/double base propellant (DB) mass ratios under argon atmosphere were studied by the thermogravimetry–differential scanning calorimetry–mass spectrometry–Fourier transform infrared spectroscopy (TG–DSC–MS–FTIR) and automatic calorimeter method. The results show that decomposition process of AP/DB samples in negative and zero oxygen balance (OB) is different from that in positive OB. With the increasing of AP in the AP/DB samples, the decomposition of the samples becomes more and more severe. When the OB of the samples is positive, the phenomenon of deflagration or explosion could be observed in the decomposition process. The sample with OB = 0 has the greatest heat of combustion.     

Nitrato Functionalized Polymers for High Energy Propellants and Explosives: Recent Advances

Future propellants and explosive research focus on developing compositions with less vulnerability without compromising performance. This has provided impetus for research in the area of high energy materials and compounds free from pollution, for safe handling, high performance, reliability and reproducibility. The energetic oxidizers and energetic binders are being developed in this scenario for use in composite propellants and explosives. In a propellant, the binder holds together the matrix containing solid oxidizer particles and finely divided metal particles. It provides structural integrity and aid the combustion of the propellant. Any new development in this area wherein the binder can contribute to the energetic is of immense importance. This can be achieved by incorporation of energetic groups such as nitrato (?ONO₂), azide (?N₃) or flurodinitro CF(NO₂)₂ as side chain or on to the existing polymer backbone. Among these, nitrato functionalized energetic binders can find application in myriad areas like boosters, plastic bonded explosives, gas generators and pyrogen igniters. The present article is a concise review on various types of nitrato binders; their synthesis, properties and their propellant studies. Copyright © 2017 John Wiley & Sons, Ltd.     

Thermal decomposition behavior, kinetics, and thermal hazard evaluation of CMDB propellant containing CL-20 by microcalorimetry

The thermal decomposition behavior of composite modified double-base propellant containing hexanitrohexaazaisowurtzitane (CL-20/CMDB propellant) was studied by microcalorimetry. The kinetic and thermodynamic parameters were obtained from the analysis of the heat flow curves. The effect of different proportion of CL-20 to the thermal decomposition behavior, kinetics, and thermal hazard was investigated at the same time. The critical temperature of thermal explosion (T _b), the self acceleration decomposition temperature (T _SADT), and the adiabatic decomposition temperature rise (??T _ad) were calculated to evaluate the thermal hazard of the CL-20/CMDB propellant. It shows that the CMDB propellant with 38% CL-20 has relative lower values of E and lgA, and with 18% CL-20 has the highest potential hazard.     

柠檬酸镧催化双基推进剂的非等温热分解反应动力学

采用TG-DTG和DSC技术研究了含二缩三乙二醇二硝酸酯(TEGDN)和硝化甘油(NG)的混合酯、硝化棉(NC)和用作燃烧催化剂的柠檬酸镧组成的双基推进剂在常压和流动态氮气气氛下的非等温热分解反应动力学. 结果表明, 该双基推进剂的热分解过程存在2个失重阶段: 第I失重阶段为混合酯的挥发分解过程; 第II失重阶段为主放热分解反应, 机理服从三级化学反应, 减速型α-t曲线, 动力学参数: Ea=231.14 kJ·mol-1, A=10^23.29 s-1, 动力学方程为dα/dt=10^22.99(1-α)³ e^-2.78×104/T. 由外推起始点温度(Te)和峰顶温度(Tp)计算得出该双基推进剂的热爆炸临界温度值分别为Tbe=463.62 K, Tbp=477.88 K. 反应的活化熵(⊿S^≠)、活化焓(⊿H^≠)和活化能(⊿G^≠)分别为219.75 J·mol-1·K-1, 239.23 kJ·mol-1和135.96 kJ·mol-1.     

The Thermal Decomposition of Triple-Base Propellants

The thermal decompositions of a double-base propellant (DB), five triple-base propellants (TB) and nitroguanidine (NGV) were examined. The kinetic parameters were evaluated using the ASTM, Kissinger, Rogers-Morris, Freeman-Carroll and Borchardt-Daniels methods. The values of the orders of some of the chemical reactions (n), like some values of activation energies (E_a), do not have any physical meaning, but they represent the manner of propellant decomposition and prove that the mechanism of the reaction changes during the decomposition process. As a result of this fact, differences appear in the evaluated kinetic parameters between various methods. This revised version was published online in August 2006 with corrections to the Cover Date.     

Compatibility study of 1,3,3-trinitroazetidinewith some energetic components and inert materials

The compatibility of 1,3,3-trinitroazetidine (TNAZ) with some energetic components and inert materials of solid propellants was studied by using the pressure DSC method. Where, cyclotetramethylenetetranitroamine (HMX), cyclotrimethylenetrinitramine (RDX), nitrocellulose (NC), nitroglycerine (NG), 1.25/1-NC/NG mixture, lead 3-nitro-1,2,4-triazol-5-onate (NTO-Pb), aluminum powder (Al powder) and N-nitrodihydroxyethylaminedinitrate (DINA) were used as energetic components and hydroxyl terminated polybutadiene (HTPB), carboxyl terminated polybutadiene (CTPB), polyethylene glycol (PEG), polyoxytetramethylene- co-oxyethylene (PET), addition product of hexamethylene diisocyanate and water (N-100), 2-nitrodianiline (2-NDPA), 1,3-dimethyl-1,3-diphenyl urea (C₂), carbon black (C.B.), aluminum oxide (Al₂O₃), cupric 2,4-dihydroxybenzoate (β-Cu), cupric adipate (AD-Cu) and lead phthalate (φ-Pb) were used as inert materials. The results showed that the binary systems of TNAZ with HMX, NC, NG, NC+NG and DINA are compatible, with RDX and Al powder are slightly sensitive, with NTO-Pb, β-Cu, AD-Cu, C.B. and Al2O3 are sensitive, and with HTPB, CTPB, PEG, PET, N-100, 2-NDPA, C₂ and φ-Pb are incompatible.     

Composite materials based on zeolite 4A for adsorption heat pumps

Some additives and binders were chosen for the preparation of 4A-zeolite-based composites with high equivalent thermal conductivity for heat pumps application. Additives (SiC, Si₃N₄, graphite) and binders (PTFE, Al(OH)₃) were tested for their effectiveness in terms of equivalent thermal conductivity and maximum water adsorption capacity of the composites. The influence of the equivalent thermal conductivity of the composite adsorbents on the specific power of the heat pump was also calculated. Results show a significant improvement in the equivalent thermal conductivity of the composite samples which are prepared using aluminum hydroxide as binder, over that of zeolite pellet beds. Such composite materials could be used to build adsorption heat pumps with higher specific power and, consequently, with lower investment cost.     

Effect of MnC2O4 nanoparticles on the thermal decomposition of TEGDN/NC propellant

The effect of MnC₂O₄ nanoparticles on the thermal decomposition of double-base propellant composed of nitrocellulose (NC) and triethylene glycol dinitrate (TEGDN) has been investigated by TG/DSC?CMS?CFTIR coupling technique. The results show that the decomposition of TEGDN/NC propellant has two stages, the first stage is the volatility and decomposition of TEGDN, the second is the decomposition of NC. The addition of MnC₂O₄ nanoparticles gets the onset temperature of first stage higher, and makes the activation energy of decomposition of TEGDN grow by about 20?C30?kJ/mol. The catalytic also accelerates the total weight loss, and makes the peak temperatures of DSC curves higher. The activation energy of the second stage has a decrease of 20?C40?kJ/mol. MS and FTIR analysis show that the catalyst gets the gas products of macromolecular significantly reduce, while small molecules increase significantly. It also results in the decrease of H₂O, N₂O, and NO₂, and the increase of NO and HCN. Above all, the catalytic improves the thermal stability of TEGDN/NC propellant, make it more safety in storage, and make the decomposition easier and more thorough in main reaction zone.     

Synthesis and stabilization mechanism of novel stabilizers for fullerene-malonamide derivatives in nitrocellulose-based propellants

Nitrocellulose (NC)-based propellants require stabilizers to avoid early decomposition or even explosion during storage. A series of novel fullerene-malonamide derivatives with different carbon chain lengths on the p-position of the benzene ring was synthesized as stabilizers for NC-based propellants through the Bingel reaction because of the excellent thermal stability and strong ability of these derivatives to eliminate free radicals. The molecular structures of these fullerene-malonamide derivatives were verified via ¹H nuclear magnetic resonance (NMR) spectroscopy, ¹³C NMR spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, ultraviolet–visible spectroscopy, and high-resolution mass spectrometry. Meanwhile, their stability was investigated using methyl violet, vacuum stability, and weight loss tests. Results indicated that the stability of the novel fullerene-malonamide derivatives was considerably better than that of traditional stabilizers, such as N,N′-dimethyl-N,N′-diphenylurea and diphenylamine. Moreover, these derivatives exhibited excellent thermal stability at high temperatures. The stability of the fullerene-malonamide derivatives also improved as the carbon chain length on the p-position of the benzene ring on C₆₀ increased. In addition, the stability mechanism of the fullerene-malonamide derivatives was studied through electron paramagnetic resonance spectroscopy, FT-IR spectroscopy, and liquid chromatography-mass spectrometry. Results turned out that the fullerene-malonamide derivatives could react with nitroxide radicals released from the pyrolysis of NC. Hence, these novel fullerene-malonamide derivatives can be used as promising stabilizers for NC-based propellants.     

Graphitic carbon nitride embedded hydrogels for enhanced gel electrophoresis

Here, we show, for the first time, the use of graphitic carbon nitride (g-C₃N₄) nanosheets to improve the resolution and efficiency of protein separation in gel electrophoresis. By loading 0.04% (m/v) g-C₃N₄ nanosheets into the polyacrylamide gel at 25 °C, the thermal conductivity increased approximately 80% which resulted in 20% reduction in Joule heating and overall increase of separation efficiency. Also, polymerization of acrylamide occurred in the absence of tetramethylethylenediamine (TEMED) when the polyacrylamide gel contained g-C₃N₄ nanosheets. Hence, the g-C₃N₄ act simultaneously as a polymerization catalyst as well as heat sinks to lower Joule heating effect on band broadening.     

Effect of some metallic additives (Ag, Cd, and Sn) on thermal transport properties of a-Se

In this study, we have studied the effect of elements Ag, Cd, and Sn as chemical modifiers on some thermal transport properties (thermal conductivity, diffusivity, and specific heat per unit volume) of amorphous Se. Concurrent measurements of thermal transport properties such as effective thermal conductivity (??_e), thermal diffusivity (??_e), and specific heat per unit volume (??C _v) are used at room temperature for twin pellets of pure Se- and Se-based binary Se₉₈M₂ (M?=?Ag, Cd, and Sn) alloys using transient plane source technique. We have also determined the thermal inertia I _T using the experimental values of thermal conductivity and specific heat per unit volume for present amorphous alloys. The increasing sequence of measured thermal transport properties is also discussed.     

Comprehensive survey of Nd substitution In La2Mo2O9 oxide-ion conductor

Differential thermal analysis coupled to temperature-controlled diffraction have given evidence of a topological metastability phenomenon in an extended compositional range of the La_2−xNd_xMo₂O₉ solid solution. A metastable-stable phase diagram is proposed for this series of LAMOX-type fast oxide-ion conductors. In the Nd range 0<x?0.35, a freezing of the oxygen/vacancy disorder of the β-phase at ambient temperature can be achieved through a splat-quenching to water-ice mixture or/and shaping/sintering into pellet. In the intermediate 0.4?x?1.2 range, the amount of β-metastable phase grows upon substitution for powders. The negative impact of β-metastable to α phase transition on conductivity tends to disappear through the partial stabilization of the β phase by shaping/sintering.