Combustion of GAP/HMX and GAP/TAGN Energetic Composite Materials

Energetic composite materials (ECM) have high thermodynamic potential and flexible design capability. Two types of ECM were formulated as mixtures of glycidyl azide polymer (GAP) and crystalline materials. The crystalline materials evaluated were cyclotetramethylene tetranitramine (HMX) and triaminoguanidine nitrate (TAGN). The thermochemical properties of HMX and TAGN were different to each other: HMX is a high energy material but the burning rate is lower than that of TAGN. TAGN produces hydrogen as a combustion product and the thermodynamic potential becomes high even though the flame temperature is low. The results of burning rate measurement tests indicate that the burning rates of both ECM are decreased significantly by the addition of HMX and TAGN even though the burning rates of GAP, HMX, and TAGN are higher than those of the ECM. The temperature sensitivity of burning rate of GAP is reduced significantly by the addition of HMX and remains unchanged by the addition of TAGN. The reduced burning rates of GAP/HMX and GAP/TAGN are caused by the reduced heat flux transferred back from the gas phase to the burning surface. The reduced heat release at the burning surface of GAP/HMX is responsible for the reduced temperature sensitivity.     

含能聚合物/硝基胍复合含能材料的制备及表征

以含能聚合物(EP)和硝基胍(NQ)为原料,采用溶剂/非溶剂法制备了EP/NQ复合含能材料,采用扫描电镜(SEM)、比表面积测试法(BET)和X射线衍射(XRD)对其形貌和结构进行了表征,用热重-差示扫描量热法(TGDSC)对比分析了EP/NQ复合含能材料及其物理共混物的热性能。结果表明,EP/NQ复合含能材料具有三维纳米网络结构,NQ沉积在EP上面,其平均粒径为49~62nm,NQ的长针状结晶消除;与EP相比,EP/NQ复合含能材料的比表面积降低,且随着NQ质量分数由40%增至60%,EP/NQ复合含能材料的比表面积由54.599m2/g降至25.02m2/g;EP/NQ复合含能材料具有单一的热分解峰特性,热分解峰温比NQ提前55~59℃,且随着NQ质量分数由40%增至60%,EP/NQ复合含能材料的热分解峰温由200.1℃升至203.7℃;EP/NQ复合含能材料的分解热显著高于EP/NQ物理共混物。     

Preparation and Properties of HMX Coated with a Composite of TNT/Energetic Material

To improve the safety of HMX without sacrificing energy properties, the composites of TNT and an energetic material (HP‐1) were used to coat HMX particles by a method of integrating solvent–nonsolvent with aqueous suspension‐melting. SEM (scanning electron microscopy) and XPS (X‐ray photoelectron spectrometry) were employed to characterize the samples. The effect of the processing parameters, such as mass ratio of HP‐1 to TNT (MRHT), stirring speed, and cooling rate, on the quality of coated samples were investigated and discussed. The mechanical sensitivity, thermal sensitivity, thermal decomposition characteristic, and heat of detonation of raw and coated HMX samples were also measured and contrasted. Results show that when MRHT, stirring speed in the second stage and cooling rate are 1 : 5, 1000 r⋅min⁻¹ and 5 °C⋅min⁻¹ respectively, the optimal coating effect is achieved. Compared with that of raw HMX, both impact and friction sensitivity of HMX coated with 2.5 wt.‐% TNT and 0.5 wt.‐% HP‐1 decrease obviously, whereas there is a slight change in their thermal sensitivity and thermal decomposition characteristics. Meanwhile, such surface coating does not result in the decrease of its energy properties.     

Thermal Decomposition of Energetic Materials 81. Flash Pyrolysis of GAP/RDX/BTTN Propellant Combinations

The pyrolysis of a 50/50 mixture of RDX/GAP‐diol cured with the isocyanate compound N‐100, and a 70/21/9 mixture of RDX/BTTN/ GAP‐polyol cured with HMDI were studied by the T‐jump/FTIR spectroscopy technique. To understand the behaviors better, pyrolysis was also conducted on pure N‐100, pure BTTN, GAP‐diol cured with N‐100, and 70/30 BTTN/GAP‐polyol cured with HMDI. Pure N‐100 and the cured propellants liberate a large quantity of HMDI upon pyrolysis. This result reveals that the urethane bonds break early in the reaction sequence and the curing agent begins to vaporize from the matrix. The 50/50 RDX/GAP mixture decomposed with relatively little smoke or residue, which sharply contrasts with its reported behavior upon combustion. The difference can be attributed to the mismatch between the heating rates of flash pyrolysis and combustion. During pyrolysis the RDX and GAP are able to remain in contact longer such that fuel‐oxidizer reactions occur between them. During combustion the two compounds may segregate due to evaporation of most of the RDX. Hence the GAP decomposes in the condensed phase giving smoke and residue without the benefit of oxidation by NO₂ from the RDX. This discrepancy does not exist with the more fuel‐oxidizer balanced 70/21/9 mixture of RDX/BTTN/GAP, where the interaction of the fuel and oxidizer species is strong.     

含快燃物改性双基推进剂燃速模型的建立

建立了含4种不同晶形快燃物(立方体、球形、长方体、片状)无烟改性双基推进剂的燃烧数学模型,推导出推进剂燃速数学表达式,以及在推进剂燃烧方向上快燃物有效使用粒径的数学表达式。运用建立的数学模型分别计算了含5％和7％快燃物ACP的某推进剂在不同压强下的燃速,计算结果与实测燃速基本吻合。     

含能聚氨酯热塑性黏合剂GAP/PBAMO的性能

以聚双叠氮甲基氧杂环丁烷(PBAMO)为硬段,聚缩水甘油醚(GAP)为软段,采用一锅法扩链合成了含能聚氨酯黏合剂(GAP/PBAMO).实验中合成了不同硬段含量的黏合剂,并采用FT-IR、NMR、GPC、XRD、DSC和SEM等对其结构和性能进行了表征.结果表明,硬段质量分数为66.7%时,该热塑性黏合剂具有较好的耐热...     

纳米多孔硅基复合含能材料的研究进展

综述了纳米多孔硅和纳米多孔硅基复合含能材料的国内外研究现状,通过分析认为该类复合含能材料具有反应活性高、能量可控、性能可调以及燃烧产物污染小等优点,具有很好的应用前景,但从目前的研究现状来看,还存在感度高、安全性能差、易氧化等缺点,且其爆炸反应机理也不明确,还需进一步进行制备工艺和爆炸反应机理方面的研究。     

Optical Properties of Energetic Materials: RDX,HMX, AP,NC/NG,and HTPB

Optical properties of RDX, HMX, AP, HTPB/IPDI and a catalyzed NC/NG propellant (N5) were obtained from 2.5 μm to 18 μm using FTIR transmission spectrometry. Scattering-corrected KBr pellet methodology was used for the crystalline materials. Absorption index (k) was measured directly and refractive index (n) was deduced using dispersion theory. At 10.600 μm the absorption coefficients were AP, 190 cm⁻¹ (240 cm⁻¹ at 10.6036 μm); HTPB/IPDI, 360 cm⁻¹; N5, 510 cm⁻¹; RDX, 2800 cm⁻¹; and HMX, 5670 cm⁻¹.     

铜-铅-炭复合燃速催化剂的制备及性能

以铜-铅螯合物为活性组分,介孔炭为载体,采用反应沉淀制备了铜-铅-炭复合燃速催化剂.通过N2吸附-脱附、SEM、TG和DSC等对其进行表征.结果表明,铜-铅螯合物呈不规则球形,铜铅-炭复合催化剂呈球花状.BET比表面积为28 m2/g,孔容为0.012 cm3/g.在20 MPa压强下含铜-铅-炭复合催化剂的双基推进剂...     

Composite Energetic Materials Containing Nitrotriazalone Formed by Molecular Inclusion

The explosive properties of inclusion compounds containing the monoanion of the energetic compound 3‐nitro‐1,2,4‐triazol‐5‐one (NTO⁻) non‐covalently bound to either of two larger, energetic, receptor complexes, namely 1‐(2,4‐dinitrophenyl)‐1,4,7,10‐tetraazacyclododecanezinc(II) or 1‐(2,4‐dinitrophenyl)‐1,4,7,10‐tetraazacyclododecanecopper(II), both as their monoperchlorate salts, are reported. The sensitivity of the receptor host–guest complexes to electrostatic discharge or friction was not found to differ from that displayed by the separate components. However, for thermal sensitivity it was found that whereas NTO⁻ desensitized the Zn(II) receptor complex it sensitized the Cu(II) receptor complex. For sensitivity to impact, measured using the Rotter impact test, it was found that NTO⁻ sensitized the Zn(II) receptor complex, but desensitized the Cu(II) receptor complex.     

Combustion of GAP Based Energetic Pyrolants

Glycidyl azide polymer (GAP) is a high energy material used as a fuel component and binder of propellants and gas generators. High temperature products are formed by the scission of the chemical bond N₃ when GAP is decomposed. The major decomposition products are N₂, CO, and C. Though GAP contains no oxidizer fragments in its products, an addition of metal particles increases the energy of GAP. A mixture of GAP and metal particles forms a high energy metal based GAP pyrolant, i.e. GAP/metal pyrolant. The metals examined are Al, Mg, B, Ti, and Zr. The results indicate that the thermal decomposition and burning rate are dependent on the type of metals mixed.     

CL-20/开口多壁碳纳米管复合含能材料的制备与性能

以开口多壁碳纳米管(SMWNTs)为原料,六硝基六氮杂异伍兹烷(CL-20)为填料,采用超声吸入法制备CL-20/SMWNTs纳米复合含能材料;利用TEM、DSC-TG、XRD对样品进行表征,并对其进行激光点火试验。结果表明,CL-20晶粒填充到SMWNTs内部,填充部位在SMWNTs的端口,呈颗粒状排列。与纯CL-20相比,CL-20/SMWNTs纳米复合含能材料的起始分解温度由原来的239.6℃降至229.6℃,分解峰温也由原来的221.4℃降至173.6℃。CL-20/SMWNTs纳米复合含能材料光敏感性强,激光能量50W时可将其点燃。     

Iron Nanoparticle Additives as Burning Rate Enhancers in AP/HTPB Composite Propellants

Burning rate measurements were carried out for ammonium perchlorate/hydroxyl‐terminated polybutadiene (AP/HTPB) composite propellants with iron (Fe) nanoparticles as additives. Experiments were performed in a strand burner at pressures from 0.2 to 10 MPa for propellants containing approximately 80 % AP and Fe nanoparticles (60–80 nm) at concentration from 0 to 3 % by weight. It was found that the addition of 1 % Fe nanoparticles increased burning rate by factors of 1.2–1.6. Because Fe nanoparticles are oxidized on the surface and have high surface‐to‐volume ratio, they provide a large surface area of Fe₂O₃ for AP thermal decomposition catalysis at the burning propellant surface, while also providing added energy release due to the oxidation of nanoparticle sub‐shell Fe. The increase in burning rate due to Fe nanoparticle content is similar to the increase in burning rate caused by the addition of iron oxide (Fe₂O₃) particles observed in prior literature.     

ABS/改性高岭土复合材料的制备与表征

高岭土经乙酸钾插层处理后,与γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(KH570)水解液混合研磨,制备了偶联剂表面处理的插层型高岭土,并与丙烯腈-丁二烯-苯乙烯共聚物(ABS)进行熔融共混制得ABS/插层型高岭土复合材料。采用傅里叶变换红外光谱仪(FTIR)、X射线衍射仪(XRD)对高岭土改性效果进行表征,采用扫描电子显微镜(TEM)、热失重分析仪(TG)、拉伸试验等研究了ABS/改性高岭土复合材料的微观形貌、热、力学性能。结果表明,改性高岭土层间距为1.42 nm,插层率为79.7%,改性高岭土加入量为3%、7%时,片层较均匀分散在ABS基体中;当改性高岭土的填充量为7%时,复合材料的断裂伸长率比纯ABS增加157.1%,热分解温度也有所提高。     

聚苯胺/nano-ATO导电复合材料的原位聚合与表征

用原位聚合法,以十二烷基苯磺酸(DBSA)/HC l混酸为掺杂剂,过硫酸胺(APS)为氧化剂,制备了聚苯胺/掺锑二氧化锡(ATO)导电复合材料。探讨了ATO用量对导电复合材料电导率的影响。在n(苯胺)∶n(APS)∶n(DBSA)=1∶1∶0.7,m(ATO)∶m(苯胺)=0.1∶1时,复合材料室温25℃的电导率最高可达8.35 S/cm,比通常方法合成的聚苯胺和nano-ATO的电导率分别提高约1至2个数量级。通过FTIR、XRD、SEM和TEM对目标物进行了表征,结果表明,苯胺优先在ATO纳米粒子表面聚合,形成聚苯胺包覆ATO的导电复合材料。     

多孔Fe2O3/Al复合含能材料的制备与表征

用溶胶-凝胶法结合超临界干燥法,制备了Fe2O3/Al复合含能材料。用SEM、XRD、BET等方法对Fe2O3/Al复合含能材料的结构进行了表征。结果表明,超临界法制备的Fe2O3/Al复合含能材料呈明显的纤维网络状结构;其中Al的平均粒径为40nm;比表面积为147.9m2/g,相比空白Fe2O3气凝胶明显下降,平均孔径为8nm,孔径分布比较均匀。     

Effect of Voids inside AP Particles on Burning Rate of AP/HTPB Composite Propellant

Bubble contamination in an ammonium perchlorate (AP)‐based composite propellant has a positive effect on the burning rate. However, the quantitative effect of the bubble contamination on the burning rate has never been revealed. In order to clarify the relationship between the increase in the burning rate and the void fraction of the propellant, propellants were prepared with fine porous AP particles (PoAP) or fine hollow AP particles (HoAPs), and their burning rate characteristics were investigated. The voids inside AP particles have the effect of increasing the burning rate. The increase in the burning rate is enhanced linearly as the void fraction increases. The effect of the void fraction on the burning rate for a propellant containing PoAP is not identical with that for a propellant containing HoAP. It was found that the effect of the void fraction on the burning rate could be estimated by the void fraction when the bubble contamination is uniform in size and shape.     

Analytical Characterization of Impurities or Byproducts in New Energetic Materials

In the last years several new explosives have recently attracted attention as possible alternatives, e.g. for the nitramines RDX and HMX. Hexanitrohexaazaisowurtzitane (HNIW) also known as CL 20 is one of them. Objective of the study was to analyse three different CL 20 samples from different suppliers (ϵ-CL 20 from Thiokol, USA and ϵ- and β-CL 20 from SNPE, France) with chromatographic and spectroscopic techniques to characterize the chemical and polymorph purity of the materials in order to compare the different samples to each other. From IR-spectroscopic measurements it was determined that all three materials have polymorph purities >95%. To get informations about the chemical purity and possible byproducts or residual solvents the samples were analysed by HPLC, NMR and GC-MSD. For the last a new technique, the so called Solid Phase Micro Extraction, SPME was applied for sample preparation. The chemical purity estimated by HPLC analysis was for all CL 20 samples >96% while the ϵ-charge of SNPE had the highest purity (98.3%). From NMR-measurements an acetyl- or formyl-substituted byproduct was identified. From NMR as well as from GC-MSD analyses residual amounts of organic solvents have been detected (ethanol or tetrahydrofuran). Furthermore different spare amounts of other organic components were identified after SPME-treatment and characterization with GC-MSD.     

Fabrication and Properties of Insensitive CNT/HMX Energetic Nanocomposites as Ignition Ingredients

Cyclotetramethylene tetranitramine (HMX)‐coated carbon nanotube (CNT) nanocomposites with uniform structures were prepared using the recrystallization method. Characterization (SEM, TEM, XRD, BET, etc.) was performed to determine the micromorphology, crystal structure, and specific surface area. The energetic particles were homogeneously distributed on the surfaces of the CNTs, and the maximum thickness of the coating layer was approximately 120 nm, whereas the average crystal size was less than 50 nm. The test results of the thermal behavior showed that the thermal decomposition temperature decreased as the CNT content increased, and the maximum thermal conductivity was approximately 27.3 times higher than that of pure HMX. The sensitivities of the CNT/HMX nanocomposites to impact, friction, and shock were maximally reduced by 73 %, 29 %, and 74 % compared with those of pure HMX, respectively, which demonstrated a significant safety improvement. In the CNT/HMX nanocomposites, aluminum and ferric oxide were used to fabricate a new type of ignition composition. Based on comparative studies, the results showed that the ignition composition was porous and that its particles were more evenly distributed compared with the conventional counterparts. The thermal conductivity was improved by 21 %. The impact and friction sensitivities were also maximally reduced by 21 % and 27 %, respectively. The combustion heat was also increased by 9 % compared with that of a mixture of the same components.