Detonation properties of ammonium nitrate/nitramine-based composite propellants

ABSTRACT

Ammonium nitrate (AN) propellants have attracted attention because of their low cost and ecofriendliness despite certain major disadvantages such as low burning rate, poor ignitability, low energy, and volume change due to phase transition of AN. The addition of nitramine to AN propellants is one of the approaches to overcome these disadvantages. However, AN/nitramine propellants are characterized by easy initiation, high sensitivity, and high detonation velocity because of the high energy of nitramine. The detonation properties of AN/nitramine propellants were investigated in this study. It was observed that the AN/nitramine propellant required a booster to detonate the propellants, as detonation did not occur while using only a commercial electric blasting cap. It was further observed that the detonation velocity (D) increased linearly as the mass of nitramine per unit propellant volume was increased, and AN had a negligible effect on the detonation properties. An approximate equation was derived from the relationship between D and the mass per unit propellant volume of nitramine. The dominant factors that can be used to estimate the detonation/no-detonation boundaries of the propellants were identified, and the experimental boundary equations were determined using these factors.     

Effect of certain lead and copper compounds as ballistic modifier for double base rocket propellants

Abstract

During our search for better burn rate catalysts and platonizers the effect of lead oxide with lead copper salts of organic acids was studied. Basic lead and copper salts of aliphatic acids have been found to produce more or less similar catalytic and plateau effects, whereas basic copper salts of aromatic acids were comparatively more effective in producing higher burn rates than basic lead salts, although reduction of pressure index values was more pronounced with basic lead salts. The results have been explained in the light of existing theories on catalysis and platonization.     

Influence of 1,4-dinitropiperazine (DNP) on the pressure index of rdx containing extruded double base propellants

Abstract

Effect of 1,4-dinitropiperazine (DNP) in bringing down the pressure index (n) in RDX - containing extruded double base propellents has been studied. Experiments have been conducted on two sets of formulations based on controls of low calorimetric value (870 cal/g) and high calorimetric value (1070 cal/g). RDX content was varied between 10 and 20% and DNP content from 2 to 6 parts per 100 parts of the base composition. DNP alone does not bring down n appreciably; however, in conjuction with Basic Lead Salicylate, a well known ballistic modifier (2 parts), it brings down the n in the 70–105 kg/cm² pressure range significantly. The effect is more pronounced in the low calorimetric value compositions and a plateau effect has been observed. Addition of dinitropiperazine does not adversely affect the thermal and chemical stability of the formulations nor their mechanical properties. The temperature sensitivity of burn rate of DNP containing formulations was reduced to 0.21% / °C as compared to that of the control having of 0.32% / °C.     

Lead salt of 2, 4, n-trinitroanilinoacetic acid - an energetic ballistic modifier for double base propellants

Abstract

Lead Salt of 2,4,N-trinitroanilinoacetic acid has been evaluated as ballistic modifier in composite modified double base matrix. Burn rate measurements showed a plateau effect between 3.43 — 8.82 MPa. The salt-containing propellant composition showed a synergistic effect on decomposition of propellants as evidenced by a reduction in differential thermal analysis exotherm peak temperature. Effect of magnesium oxide-lead salt combination on burn rate of propellant formulation was also evaluated. The combination increased the burn rate at 6.86 — 8.82 MPa and decreased at 10.78 MPa. The salt has been prepared by double decomposition of lead nitrate with sodium salt of 2,4,N-trinitroanilinoacetic acid, which in turn is prepared from glycine and 2,4 - dinitrochlorobenzene. The lead salt decomposes at 187°C as shown by differential thermal analysis exotherm. Calorimetric value (+3.14 MJ/kg) of the salt has been calculated. The salt exhibits an impact sensitivity height (h₅₀) of 97.5 cm and friction sensitivity of >36 kg.     

Tuning the thermal,mechanical, and combustion properties of NC-TEGDN-RDX propellants via incorporation of graphene nanoplates

ABSTRACT

Graphene nanoplates (GNPs) were incorporated into a solid composite propellant (NC-TEGDN-RDX) to tune the thermal, mechanical, and combustion properties of the material. Physical, thermal, and combustion properties of NC-TEGDN-RDX with <2 wt% addition of GNPs were characterized using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), tensile/compressive/impact strength testing, and constant volume combustion experiments. Microstructure of the composite propellants examined using SEM demonstrated uniform dispersion of the GNPs at low-weight percent additives (<1 wt%), but began to show large agglomerations of the additives at higher additive content. Decomposition enthalpy of the propellant with 1 wt% GNPs increased by ~130 J/g compared to neat propellants. Moreover, the maximum burning rate was observed for samples containing 1 wt% GNPs, with values of 19 cm/s at 20°C and 17 cm/s at ?40°C. Dynamic vivacity of the propellant achieved a maximum upon addition of 1 wt% GNPs. The pressure exponent of the propellant decreased with the addition of GNPs, as well. The mechanical properties including tensile, compressive, and impact strength were improved at 20°C and ?40°C. These results demonstrate that the addition of GNPs may offer new methods by which to tune and improve thermal decomposition, thermal conductivity, combustion performance, and mechanical properties of the NC-TEGDN-RDX propellants.     

基质沥青与 SBS 改性沥青的老化性能分析

以辽河AH90沥青为基质沥青,在其中加入质量分数为3%的苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)改性剂,可制备改性沥青。利用沥青软化点随时间的变化关系,建立了2种沥青的老化动力学模型:lnR基=3.784 1.33×103texp(-4946/T),lnR改=3.949 1.54×103texp(-5 242/T)。通过比较2种沥青的动力学参数,得出改性沥青的抗老化性能优于基质沥青。借助红外光谱分析可知,基质沥青的老化主要是吸氧氧化反应;而改性沥青的老化除了具有基质沥青的老化反应外,还存在SBS中聚丁二烯链段的断裂和氧化反应。     

聚丙烯催化合金的力学性能与结构分析

利用选择性溶解、核磁共振(13C-NMR)、扫描电子显微镜(SEM)等方法对釜内聚丙烯催化合金(PP-c)3个试样的分子序列组成和相形貌进行了分析,并与其力学性能进行了关联。结果表明,合金的力学性能与其乙丙无规共聚物EPR含量、长序列嵌段共聚物EEP和EEE含量以及总乙烯含量密切相关,这些组分含量的提高有利于合金刚性和韧性的增强;橡胶相尺寸适中且分布均匀也有助于合金力学性能的提高。     

Liquid chromatography of firearms propellants traces

Most of the major components of firearms propellants likely to occur on the skin or clothing after the discharge of a firearm may be detected sensitively and with substantial specificity by liquid chromatography methods. The components Include nitrocellulose, nitroglycerin and diphenylamine. Impurities and metabolites of nitroglycerin may occur on the skin. On clothing the traces are strongly persistent. The techniques employed include size-exclusion and high-performance liquid chromatography, with amperometric detection at a mercury drop electrode, and coulometric detection at porous carbon electrodes. Progress in the use of the Thermal Energy Analyser as a complementary technique is reported.     

Supercritical water oxidation of chemical agents,and solid propellants

Abstract

Supercritical water oxidation (SCWO), also referred to as hydrothermal oxidation (HTO), is a developing technology for the destruction of hazardous and nonhazardous wastes. SCWO destroys combustible materials using an oxidant in water at temperatures in the range of 350°C (662°F) to 600°C (1112°F) and pressures of 17 MPa (2500 psi) or greater. General Atomics and its subcontractors are currently conducting two comprehensive research and demonstration programs geared toward the destruction of Department of Defense (DoD) wastes utilizing SCWO technology. Wastes of primary interest include chemical agents and solid propellants. Technical challenges, particularly corrosion and solids handling, were overcome, and the destruction of chemical agents and solid propellants was demonstrated on a bench scale. SCWO results for chemical agents show destruction and removal efficiencies for GB, VX, and mustard agents to be in excess of 99.9999%, limited only by detection capability. SCWO results for hydrolyzed Class 1.1 solid propellant show destruction and removal efficiencies for total organic carbon (TOC) of >99.9%. Design and fabrication of a transportable SCWO pilot plant for chemical warfare agents, propellants and other DoD hazardous wastes and a prototype HTO system for solid rocket propellant disposal are complete and demonstration testing is underway.     

酸碱性和氧化还原性对负载型钒基催化剂丙烷氧化脱氢性能的影响

用ＸＲＤ、Ｒａｍａｎ、ＴＰＲ和Ｐｙ－ＩＲ表征乙酰丙酮络钒法制备的不同氧化物和磷酸盐负载的钒氧化物催化剂，结果表明，钒氧化物在载体ＭｇＯ、Ａｌ２Ｏ３、Ｍｇ３（ＰＯ４）２、ＡｌＰＯ４和Ｚｒ３（ＰＯ４）４上是高分散的，没有生成明显的Ｖ２Ｏ５晶相；催化剂的可还原性与相应载体氧化物或磷酸盐的金属还原电位序有较好的对应关系，同时与其丙烷氧化脱氢活性也存在较好的平行关系，表明钒氧化物与载体的阳离子形成Ｖ－Ｏ－Ｍ桥键，该桥键氧较易移去，可能是丙烷氧化脱氢的活性氧物种；催化剂表面酸性位有利于丙烷Ｃ－Ｈ键的活化，但导致深度氧化产物增多。     

Influence of metal salts of 4-(2, 4, 6-trinitroanilino) benzoic acid on the burnining rate of double base propellants

Abstract

Cobalt, Nickel, Copper and Lead salts of 4-(2, 4, 6-trinitroanilino) benzoic acid have been evaluated as ballistic modifiers in double base propellant formulations. Measurements showed considerable increase in burning rate over the control propellant, in presence of salts at all pressures in the range 3.43 – 8.82 MPa. The effect of the lead salt, however, was more pronounced and showed a burning rate increase of 50 – 60%; the lower pressure ranges showing higher burning rate enhancement. The salts decompose exothermically: cobalt salt at 270°C (initiation), nickel salt at 300°C, copper salt at 240°C and lead salt at 260 °C.     

茂金属聚乙烯与通用型聚乙烯共混物的物理机械性能与流变行为

用茂金属线性低密度聚乙烯（mLLDPE）与3种通用型聚乙烯[线性低密度聚乙烯（LLDPE）,低密度聚乙烯（LDPE1,LDPE2）]进行了共混,研究了mLLDPE质量分数对共混物物理机械性能及流变行为的影响。结果表明,当mLLDPE质量分数大于30％时,mLLDPE／LDPE 1共混物的拉伸强度得到改善;当mLLDPE质量分数为20％时,mLLDPE／LDPE2（或LLDPE）共混物的拉伸强度较纯LDPE2（或LLDPE）提高了约25％（或约13％）;在高剪切速率下,不同组成的mLLDPE／LLDPE共混物表观黏度差别不大;用mLLDPE与通用型PE共混物吹制薄膜时,共混物能耗较通用型PE有所提高,但薄膜的撕裂强度和拉伸强度有所提高。     

Burning rate of artificially aged solid double-base gun propellants

ABSTRACT

Nitrocellulose (NC) and nitroglycerin (NG) are conventional energetic ingredients of solid double-base gun propellants. NC and NG are aliphatic nitrate ester compounds that are manufactured by nitrating through immersion in acid. Solid propellants are used in a wide range of both civilian and military applications, for example, as gas generators in airbags, as fuels in rocket motors or to shoot projectiles in guns. In all illustrations, the function of solid propellant is to generate gas, which is then employed to do mechanical work. The maximum pressure and the projectile velocity are important parameters of the interior ballistic process. The goal of the interior ballistic design of the gun is to attain a higher muzzle velocity under the smaller maximum chamber pressure. The burning rate of the propellant directly affects the formation rate of burning gases, which affects the ballistic parameters, either by diminishing the ballistic effectiveness or raising the safety hazard to the operator during firing. Note that the effect of the change of burning rate is not always negative; the fact is that we could change/control the burning rate to get better ballistic performances, includin ballistic efficiency as well as launching safety. Nevertheless, nitrate ester propellants are subjected to physical and chemical degradation during storage and this can modify the burning rate. Here we describe the effect of aging on the burning rate of spherical double-base propellants both qualitatively and quantitatively. We experimented unaged propellant, and propellant that was artificially aged at 71°C and 80ºC. The durations of heating at 71ºC were 10, 20, 30, 37, 48 and 62.5 days, respectively. The durations of heating at 80ºC were 1.8, 3.63, 5.41, 7.22, 9.02 and 10.83 days, respectively. The burning rate of investigating propellant was obtained by using closed-vessel experiments. The results show that towards low pressures, the burning rate increased with aging. Towards high pressure, the burning rate decreased as a function of aging. The effect of aging was quantified by the determination of defined aging sensitivity coefficients.