Journal Cover Propellants, Explosives, Pyrotechnics
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   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0721-3115 - ISSN (Online) 1521-4087
   Published by John Wiley and Sons Homepage  [1577 journals]
  • Study on Dynamic Burning Rate Equation of Propellant
    • Authors: Ruihua Zhang; Xiaoting Rui, Yan Wang, Chao Li
      Abstract: Aiming at the difficulty that the actual burning law of propellant in the gun bore couldn't be described exactly by static burning rate equation in the closed-bomb, propellant dynamic burning rate equation and its acquisition method were established in the paper, which are based on static burning rate equation and considering burning gas flow and loading density influence factors in bore. A numerical code for interior ballistic two-phase flow was successfully developed. And corresponding firing tests were also carried out. The comparison of simulations with interior ballistic code and firing test results show that the propellant dynamic burning rate equation makes the maximum errors of muzzle velocity and pressure in breech decreased from 2.97 % to 0.75 % and from 6.68 % to 0.38 %, respectively. This method not only improves simulation precision of gun muzzle velocity and pressure significantly, but also provides a means to improve the design accuracy for interior ballistic performance.
      PubDate: 2017-05-02T10:27:09.420693-05:
      DOI: 10.1002/prep.201700021
       
  • A Novel Method to Prepare Nano-sized CL-20/NQ Co-crystal: Vacuum Freeze
           Drying
    • Authors: Han Gao; Ping Du, Xiang Ke, Jie Liu, Gazi Hao, Teng Chen, Wei Jiang
      Abstract: Nano-sized energetic co-crystal consisting of the most powerful used military explosive 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and a typical insensitive explosive used in propellants nitroguanidine (NQ) was prepared by vacuum freeze drying method. Material studio 6.1 was used to simulate the hydrogen bonds between CL-20 and NQ molecules. Scanning electron microscopy (SEM) was used to reveal the morphology and size of the product. Fourier Transform infrared spectroscopy (FT-IR) and X-ray diffraction spectrum (XRD) proved the formation of the co-crystal at the molecular level. Differential scanning calorimetry (DSC) was employed to characterize the thermal behavior of the co-crystal. The result of mechanical sensitivity test indicated the sensitivity was effectively reduced compared to neat CL-20.
      PubDate: 2017-05-02T10:26:56.250338-05:
      DOI: 10.1002/prep.201700006
       
  • Dynamic Compressive Properties of Polymer Bonded Explosives under
           Confining Pressure
    • Authors: Youcai Xiao; Yi Sun, Xiao Li, Qiuhua Zhang
      Abstract: Passively confined dynamic impact experiments on PBX1314 specimens are performed by employing aluminum jackets with split Hopkinson pressure bar. The axial and radial stress history curves are measured in the experiments, and the characterizations of the behavior of PBX1314 under dynamic multi-axial loads are studied. A constitutive relation is developed for modeling the dynamic mechanical responses of PBX1314 by using the Boltzmann superposition principle with a Prony series representation. The material parameters of PBX1314 can be obtained by fitting the modulus master curve. Detailed finite element simulations of the passively confined tests are carried out to evaluate the measure accuracy of the device to the material mechanical behavior. The correctness of the constitutive relation is verified by comparison the finite element simulations with the experiments. Good agreements are obtained.
      PubDate: 2017-04-20T08:22:03.201313-05:
      DOI: 10.1002/prep.201700016
       
  • Effect of TiH2 Particle Size and Content on the Underwater Explosion
           Performance of RDX-based Explosives
    • Authors: Bing Xue; Honghao Ma, Zhaowu Shen, Lijie Ren, Moujin Lin
      Abstract: Experiments were conducted to study the underwater explosion performance of titanium hydride/RDX-based (TiH2/RDX) composite explosive. Cylinder charges with different TiH2 particle sizes and contents were prepared and tested. Explosion parameters like peak overpressure, impulse, shock energy, and bubble energy were analyzed. It was notable that underwater explosion performance of TiH2/RDX composite explosive was promoted by addition of small particle size TiH2 (D50=0.96 μm), in which case increasing TiH2 content also showed a favorable effect. The maximum increments of specific initial shock energy, bubble energy, and total energy were 10.5%, 6.4%, and 7.1% respectively. However, with bigger TiH2 particle sizes (D50=20.78 μm, D50=136.74 μm), the explosion parameters and the TiH2 content showed a negative relationship, which reveals that TiH2 particle size plays an important role in determining the reactivity of TiH2. Meanwhile, the interaction between TiH2 particle size and content was significant.
      PubDate: 2017-04-19T03:47:26.964059-05:
      DOI: 10.1002/prep.201600173
       
  • Pressurized Nozzle-Based Solvent/Anti-Solvent Process for Making Ultrafine
           ϵ-CL-20 Explosive
    • Authors: Shallu Gupta; Pal Dinesh Kumar, Sandeep Sharma, Gurvinder Kaur, Arun Agarwal, Prem Lata
      Abstract: CL-20 explosive is one of the most recent and powerful explosives. It has very high potential in futuristic applications but at present it has limitations of sensitivity to mechanical stimuli. Among the four different polymorphs (α, β, γ, and ϵ), ϵ-polymorph has better stability and shock/detonics properties. However, preparation of pure ϵ-polymorph is a challenging task particularly in terms of repeatability and polymorphism. In our research work, pressurized nozzle based solvent/anti-solvent process (PNSAP) was developed for the preparation of ultrafine ϵ-CL-20 explosives with high repeatability, purity, and yield. To get ultrafine particle size, shape, distribution and yield, various process parameters/ variables such as solvent type, anti-solvent type, dosing rate, stirring rate, ultra-sonication, and temperature were identified and prioritized using the weighted average method of Analytical Network Process (ANP) techniques. It was observed that ultrafine ϵ-CL-20 particle size in the range of 2 to 3 μm can be obtained using this process. The ϵ-polymorph was confirmed by FT-IR characterization. The main feature of this PNSAP process is that it is a laboratory scale table-top pilot plant which is simple, cost-effective, safe and repeatable for continuous batch production of ultrafine ϵ-CL-20 at the rate of 100 grams per hour.
      PubDate: 2017-04-18T03:55:52.082035-05:
      DOI: 10.1002/prep.201700002
       
  • Evaluation of the James Initiation Criterion in the 21 mm and
           50 mm PMMA Gap Test
    • Authors: Sebastian Wurster
      Abstract: The gap test has been used for several decades as a measure for the shock sensitivity of high explosives. Normally the axial pressure in the gap is used as the necessary initiation pressure of a high explosive for a shock to detonation transition. But it has been shown in the past that the pressure in the gap is not a suitable measure for shock sensitivity and other criteria like the James criterion in terms of critical energy fluence and critical specific kinetic energy should be used. To evaluate the James criterion in the 21 mm and 50 mm polymethylmethacrylate (PMMA) gap test numerical simulations are conducted. To validate the simulations a 21 mm water gap test is simulated and compared to experimental results, where the axial pressure calibration can be reproduced with high accuracy. With the results from the simulation of the 21 mm and 50 mm gap test it is shown that at the same maximum axial pressure the energy fluence is higher in the 50 mm gap test. This explains to some extent the higher initiation pressures observed in smaller gap tests. The James criterion is derived and it is shown that the two gap tests probe very different regions in the energy fluence vs. specific kinetic energy plane. The results can be used as a calibration for the gap tests and are intended to improve the comparability of gap test results among each other and with different initiation experiments like flyer or heavy fragment impact testing.
      PubDate: 2017-04-18T03:55:27.340356-05:
      DOI: 10.1002/prep.201700012
       
  • Influence of Localized Melting on Dynamic Fracture Behaviours of Metallic
           Shell
    • Authors: Shen Zheng-xiang; Yang Hui, Li Ya-zhe, Wang Fang, Zhou Chun-hua, Zhou Ke
      Abstract: The dynamic fracture behaviour of cylindrical shell preformed by localized melting technology was studied experimentally, and the microstructure and performance of melted layers were also analyzed in this paper. The results reveal that the microstructure of melted layer is predominantly needle type and refined martensite by the melted-solidification process. With the increase of hardness and decrease of impact energy absorbed, the embrittlement tendency of localized melting sample is obviously. Compared with natural fragmentation, the fragments of shell after melting are more regular, and the proportion of effective fragments is high. Due to the sensitivity of shear bands of melted layers, fracture can easily take place along the melting trajectory subjected to internal explosive loading.
      PubDate: 2017-04-12T01:50:30.709296-05:
      DOI: 10.1002/prep.201700051
       
  • Direct Detection of Triacetone Triperoxide (TATP) in Real Banknotes from
           ATM Explosion by EASI-MS
    • Authors: Deleon Nascimento Correa; Jose J. Melendez-Perez, Jorge Jardim Zacca, Rodrigo Borges, Eduardo Morgado Schmidt, Marcos Nogueira Eberlin, Eduardo César Meurer
      Abstract: In Brazil, automated teller machine (ATM) has become a major target of theft incursions toward explosion. Efficient analysis of explosives residues on suspect banknotes is a serious issue in forensic labs, and guide to the crime solution. Easy ambient sonic-spray ionization mass spectrometry (EASI-MS) is shown to be a simple and selective screening tool to identify peroxide explosives on real banknotes collected from ATM explosion. Analyses were carried out directly on the banknotes surfaces without any sample preparation, identifying triacetone triperoxide (TATP) and diacetone diperoxide (DADP). Homemade EASI source was coupled to ultrahigh-resolution and ultrahigh accuracy FT-ICR MS and revealed the ion of m/z 245 correspondent to sodiated TATP [C9H18O6Na]+ and the ion of m/z 171 related to sodiated DADP [C6H12O4Na]+, ions that is the sodiated DADP and the ions of m/z 173 and 189 related to [C6H14O4Na]+ and [C6H14O4K]+, respectively, which are associated to chemical markers of TATP domestic route synthesis. EASI source coupled to a single quadrupole mass spectrometer provides an intelligent and simple way to identify the explosives TATP, DADP and its domestic synthesis markers.
      PubDate: 2017-04-11T02:35:30.345655-05:
      DOI: 10.1002/prep.201600046
       
  • Sequence Structure, Morphology and Viscosity Behavior of
           3,3-bis(azidomethyl) Oxetane - tetrahydrofuran random copolyether
    • Authors: Jinxian Zhai; Honghui Jia, andXiaoyan Guo
      Abstract: In order to reveal the relationship between 3,3-bis(azidomethyl) oxetane - tetrahydrofuran copolyether (P(BAMO-THF)) microstructure and its macro properties, the segment sequence structure of a kind of P(BAMO-THF) was characterized using quantitative 13C-NMR analysis. It was found that the P(BAMO-THF) is composed of equimolar comonomers whose randomness factor (R) is 1.09, belonging to a quasi-ideal random copolymer. Combining DSC and polarizing optical microscopy, it was verified that the thermal-effect between 28 °C and 41 °C attributes to the melting of the P(BAMO-THF)spherulites. Using WAXRD, it was suggested that the aggregation of BAMO micro-blocks among P(BAMO-THF) polymeric chains causes the formation of spherulites. The viscosity measurement clearly demonstrated that, below 30 °C or above 40 °C, the P(BAMO-THF) viscosities change slowly as a function of temperature. Conversely, between 30 °C and 40 °C, its viscosities sharply decline with the increase in temperature because of the changes in its morphology.BAMO equal molar ideal random copolymerization with THF cannot thoroughly overcome its crystalline, which makes P(BAMO-THF) viscosities very sensitive to temperature between 30 °C and 40 °C.
      PubDate: 2017-04-11T02:35:28.530039-05:
      DOI: 10.1002/prep.201700027
       
  • Simultaneous Determination of Multiple Mechanical Parameters for a
           DNAN/HMX Melt-Cast Explosive by Brazilian Disc Test Combined with Digital
           Image Correlation Method
    • Authors: Daoli Zhu; Lin Zhou, Xiangrong Zhang, Jiaye Zhao
      Abstract: Tensile strength, tensile modulus, compressive modulus, and Poisson's ratio are important mechanical parameters for brittle explosives. Generally, these parameters are separately measured by several different tests in which the homogeneity of specimens cannot be guaranteed, thus requiring a simultaneous determination of these mechanical parameters by one test. In this paper, simultaneous determination of multiple mechanical parameters of a DNAN/HMX melt-cast explosive using Brazilian disc test combined with digital image correlation (DIC) method is described. The method would allow tensile strength, tensile modulus, compressive modulus, and Poisson′s ratio to be obtained simultaneously by one test, when the influences of rigid body motion have been effectively removed. The method principle was introduced in detail in this paper. The effect of temperature on the mechanical properties and the difference between the tensile modulus and compressive modulus of the DNAN/HMX melt-cast explosive were investigated. The elastic constants and tensile strength were quantitatively analyzed and are qualitatively correct, which demonstrates the effectiveness of the presented method.
      PubDate: 2017-04-10T04:16:14.654168-05:
      DOI: 10.1002/prep.201700010
       
  • Enhancement of Aluminum Reactivity to Achieve High Burn Rate for an End
           Burning Rocket Motor
    • Authors: Gaurav Marothiya; P. A. Ramakrishna
      Abstract: Aluminum is used in solid propellants to increase the specific impulse (Isp). It is desirable to have high propellant loading in any stage as it reduces the structural coefficient and an end burning grain is known to be the one with the highest propellant loading. As aluminum combustion is a slow process, the time available for aluminum combustion in an end burning configuration will be very small at the start of the combustion process. This demands an increase in the reactivity of the aluminum. This study is built on the fact that mechanical activation of aluminum powder with PTFE (poly-tetra-flouro-ethylene) enhances the reactivity of aluminum powder. This study also deals with the use of this activated aluminum powder in conjunction with various other methods to enhance the burn rates of the solid propellant. The temperature sensitivity was also measured. Based on these results, new designs with end burning grains for the third stage of Polar Satellite Launch Vehicle (PSLV) and for the second and third stage of Pegasus launch vehicle have been proposed to increase the payload capacity. With this new design, it is seen that the payload can be increased by 12.7 % and 17.6 % for PSLV and Pegasus, respectively. The novelty of this design is that with no changes to any other hardware of the above two systems the increase in payload can be achieved.
      PubDate: 2017-04-10T04:15:59.929708-05:
      DOI: 10.1002/prep.201600304
       
  • Gas-phase Concentration of Triacetone Triperoxide (TATP) and Diacetone
           Diperoxide (DADP)
    • Authors: Martin A. C. Härtel; Thomas M. Klapötke, Benedikt Stiasny, Jörg Stierstorfer
      Abstract: The present investigation is about the determination of the gas phase concentration parameters of the notorious explosives triacetone triperoxide (TATP, 1) and diacetone diperoxide (DADP, 2), which have been frequently used in improvised explosive devices. According to calculations with EXPLO5 the energetic performance of both explosives is similar. The enthalpy of sublimation ΔcrgHm∘ (298.15 K) (1: 76.7±0.7 kJ mol−1; 2: 75.0±0.5 kJ mol−1) and vapor pressures psat(298.15 K) (1: 6.7 Pa, 2: 26.6 Pa) of both compounds have been studied using the transpiration method in the ambient temperature range of 274–314 K. The results obtained in this work were compared critically with the existing literature values. Data for DADP (2) mostly shows agreement with literature ones. However data of TATP (1) obtained in this work revealed insufficient agreement of all sets of data available in literature, which might be explained by the rich polymorphism of TATP 1. The saturation and diffusion equilibrium concentration of both analytes was calculated at 298.15 K. In comparison to the saturation equilibrium concentration measured in this work (1: 600 μg L−1, 2: 1589 μg L−1) the corresponding estimated diffusion condition air concentrations (1: 3.1 ng L−1, 2: 10 ng L−1, for a surface of 200 cm2) are lower by five orders of magnitude.Determination of the gas phase concentration parameters of the notorious explosives triacetone triperoxide TATP 1 and diacetone diperoxide DADP 2 is essential for conception of detector devices. Vapor pressures and enthalpies of sublimation at the ambient temperature 298.15 K have been measured with the transpiration method. The results obtained were compared critically with literature values.
      PubDate: 2017-03-31T03:15:33.855951-05:
      DOI: 10.1002/prep.201700034
       
  • The Effect of the Hydrogen Containing Material TiH2 on the Detonation
           Characteristics of Emulsion Explosives
    • Authors: Yang-fan Cheng; Xiang-rui Meng, Cheng-tao Feng, Quan Wang, Shan-shan Wu, Hong-hao Ma, Zhao-wu Shen
      Abstract: In order to improve the detonation performance of emulsion explosives, a new type of emulsion explosives with TiH2 powders is developed. The influences of the amount of sensitizers GMs and energetic additives TiH2 on explosion characteristics of emulsion explosives are studied to determine the optimum compositions. Underwater explosion and brisance testing experiments show that, compared to traditional GMs sensitized emulsion explosives, the shock wave specific impulse I and total energy E of GMs-TiH2 sensitized emulsion explosives are improved significantly, and the effect of TiH2 powders on improving the explosion power of emulsion explosives is better than that of Ti powders. The brisance of GMs-TiH2 emulsion explosives is 23.80 mm compression of lead block, 7.7 mm more than that of the emulsion explosives sensitized by GMs alone. Therefore, the hydrogen containing material TiH2 could be a promising energetic additive for developing high-power emulsion explosives.
      PubDate: 2017-03-30T06:25:36.487429-05:
      DOI: 10.1002/prep.201700045
       
  • Hypergolic Studies of Ethanol Based Gelled Bi-Propellant System for
           Propulsion Application
    • Authors: Muhammad Shoaib Naseem; B.V.S. Jyoti, Seung Wook Baek, Hyung Ju Lee, Sung June Cho
      Abstract: The experiments conducted in this study examined the hypergolicity and ignition delay of the formulated ethanol gelled fuel and hydrogen peroxide oxidizer bipropellant system. The hypergolicity and ignition delay data for bipropellant system are very important for propulsion applications. It was observed that the ethanol based gelled fuel systems were hypergolic with hydrogen peroxide (90% pure) in a presence of a suitable catalyst. The observed ignition delay was within the range of 10∼50 ms, which was comparable with the existing liquid hypergolic bipropellant systems. Temperature profile also indicated that the hypergolic system attained a very high temperature profile range of 1000 °C to 1400 °C for a very small weight percent of fuel. Experiments conducted with two separate volumes of oxidizer, 14 μl and 50 μl. In both cases the propellant system was fuel rich. It was also observed that the formation of cage in the gel network, which could encapsulate the higher temperature gases and flame in a network, might be a plausible reason for recorded higher ignition delay.
      PubDate: 2017-03-29T04:05:28.232195-05:
      DOI: 10.1002/prep.201700046
       
  • Laser-induced deflagration for the characterization of energetic materials
    • Authors: Eric S. Collins; Jennifer L. Gottfried
      Abstract: Standard propellant and detonation tests typically performed to characterize the performance of energetic materials require large quantities of material (at least tens of grams) and can be expensive and time-consuming. This work introduces a method for characterizing the deflagration of energetic materials in a laboratory setting, using only 15–20 mg of energetic material. Temperature, energy release and emission signatures were measured and analyzed for the laser-induced deflagration of 8 different conventional military explosives. Graphite nanoparticles and micron-sized aluminum powder were added to the explosive compositions to investigate their effect on the emission signatures. A high-speed color camera recorded the deflagration events and was utilized as a full-color pyrometer to calculate the average temperatures and image hotspots; the temperatures maps were compared to those measured by conventional two-color pyrometry. The laboratory-scale method presented here can be applied to novel energetic materials under development that may be available only in limited quantities to evaluate their potential as propellants or reduced emission signature explosives prior to scale-up.
      PubDate: 2017-03-29T04:00:41.497063-05:
      DOI: 10.1002/prep.201700040
       
  • Effect of Organic Fluoride on Combustion Agglomerates of Aluminized HTPB
           Solid Propellant
    • Authors: Xuyuan Zhou; Meishuai Zou, Fenglei Huang, Rongjie Yang, Xiaoyan Guo
      Abstract: Hydroxyl-terminated polybutadiene (HTPB) based propellants containing fixed aluminum content (18 wt %) and different amounts of organic fluoride (OF) additive were studied. Explosion heat of propellant samples and particle size distribution of the solid combustion products were experimentally measured to generally assess the effect of the organic fluoride compounds on propellants. Heats of explosion decreased approximately by 9.5 %, from 7209 (±259) to 6525 (±146) kJ kg−1, with the increase in OF content from 0 % to 6 %, and the volume fraction of particles size above 10 μm was sharply decreased. In addition, scanning electron microscope images showed the solid combustion products to be well separated, the titration analysis results also gave the amount of unburned metallic aluminum decreased. These results indicated that OF as an additive would be helpful to reduce agglomeration in the combustion products of aluminized HTPB propellants. Furthermore, a mechanism for suppression of agglomerate size can be postulated based on the X-ray diffraction analysis data that addition of OF promotes increased content of γ-Al2O3 (aluminum oxide) in the solid combustion products.
      PubDate: 2017-03-23T08:05:52.077831-05:
      DOI: 10.1002/prep.201600096
       
  • A New Energetic Salt Semicarbazide 5-Dinitromethyltetrazolate: A Promising
           Explosive Alternative
    • Authors: Zhi Bin Zhang; Cai Xia Xu, Xin Yin, Jian Guo Zhang
      Abstract: The design and synthesis of new environmentally friendly energetic materials with excellent performance and reliable safety have received considerable attention. A new energetic salt of semicarbazide 5-dinitromethyltetrazolate (SCZ⋅DNMZ) was synthesized by using semicarbazide and 5-dinitromethyltetrazolate (DNMZ) as raw materials, and fully characterized by using elemental analysis, FT-IR spectroscopy, 1H, 13C, and 15N nmR and mass spectrometry. The monocrystal of the salt was obtained and the structure was determined by X-ray single-crystal diffractometer. Results show that it belongs to monoclinic space group P21/c with a high density of 1.867 g cm−3. The thermal decomposition behavior was tested by DSC and TG-DTG technologies; the non-isothermal kinetic parameters for the salt were calculated. The enthalpy of formation for the salt is directly dependent on the combustion heats data with a result of 341.5 kJ mol−1, which is about three times higher than that of RDX. The detonation pressure (P) and detonation velocitiy (D) of the salt were determined as 8931 m s−1 and 36.2 GPa, which are also higher than that of RDX. The impact sensitivity was tested with a result of 10.8 J. We can draw a safe conclusion that the salt has provided a promising future by using as a kind of explosive alternative. The discovery also contributes significantly to the expansion and application of the N-heterocyclic compounds applied as energetic materials.
      PubDate: 2017-03-20T08:00:26.353924-05:
      DOI: 10.1002/prep.201600233
       
  • Projectile Impact Ignition and Reaction Violent Mechanism for HMX-based
           Polymer Bonded Explosives at High Temperature
    • Authors: Dai Xiaogan; Wen Yushi, Wen Miaoping, Huang Fenglei, Li Ming, Deng Chuan
      Abstract: Determining the mechanism of transition from projectile-impact ignition to detonation is a complex and difficult task with strong practical applications. Ignition due to low-velocity projectile impact cannot be properly explained by the available theories. We attempted to determine the mechanisms of initiation of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX)-based polymer-bonded explosives (PBXs) in a range of high temperatures, which have rarely been investigated. Comparing the shock initiation results, we found that the low-velocity projectile impact response mechanisms for a heated explosive are much more complex. Our results show that the impact ignition threshold velocity of the heated explosive does not always decrease with increasing temperature as commonly expected. A temperature dependent plastic power during impact controls the ignition in the range of 25 °C to 75 °C. At 190 °C and 200 °C, there was a sharp rise of reaction degree induced by βδ phase transition for high HMX-content PBX. Conversely, such phase transition effect becomes insignificant for low (
      PubDate: 2017-03-16T02:56:07.371102-05:
      DOI: 10.1002/prep.201600130
       
  • Direct Determination of Effective Spectral Emissivity of Hot Burnt Gas
           using Absolutely Calibrated Radiometric Spectrometer
    • Authors: Wondong Lee; Kiwook Han, Jae Won Hahn
      Abstract: Measurement of the radiative characteristics of a flame is important in the field of combustion diagnostics to better understand combustion processes, fuel performance, and combustion engine efficiency. Flame emissivity is one of the most important parameters for investigating such characteristics. This paper proposes a method to directly measure the effective spectral emissivity of a hot burnt gas in flame. We calibrate the radiometric measurement of a mid-infrared (IR) emission spectrometer using a directly heated graphite blackbody in a national standards laboratory, and determine the flame temperature by fitting the spectrum detected with the emission spectrometer to the color ratio calculated with HITEMP using the species concentrations predicted by ICT thermodynamic calculation. For proof of concept, we determine the spectral effective emissivity of the flame of an IR countermeasure flare in the spectral range of 2–5 μm. We estimate the uncertainty in the measurement to be 11.48 %.
      PubDate: 2017-03-16T02:55:49.909755-05:
      DOI: 10.1002/prep.201600199
       
  • Optimizing Code Calibration of the JWL Explosive Equation-of-State to the
           Cylinder Test
    • Authors: C. Mortensen; P. Clark Souers
      Abstract: Recent analysis of high explosives using the cylinder test has resulted in an increased understanding of the experimental uncertainty for the cylinder test. To fit the Jones-Wilkins-Lee equation-of-state model to less than experimental uncertainty, an optimization process is developed. This process, when applied to a large range of explosives, seems to show that the exponent R1 increases with increasing energy density and is grouped based on ideality. The optimal parameters are shown to increase the accuracy of an analytic equation-of-state tool.
      PubDate: 2017-03-07T03:55:31.608951-05:
      DOI: 10.1002/prep.201700031
       
  • Development of Composite Solid Propellant Based on Nitro Functionalized
           Hydroxyl-Terminated Polybutadiene
    • Authors: Hadi Abusaidi; Mostafa Ghorbani, Hamid Reza Ghaieni
      Abstract: This paper presents an overview of a modified composite propellant formulation to meet future requirements. The composite propellant mixtures were prepared using nitro functionalized Hydroxyl-Terminated Polybutadiene (Nitro-HTPB) as a novel energetic binder and addition of energetic plasticizer. The new propellant formulation was characterized and tested. It was found that the Nitro-HTPB propellant with and without energetic plasticizer exhibited high solid loading, high density, and reasonable mechanical properties over a wide range of temperatures. It was shown that the burning rate of Nitro-HTPB propellant is up to 40% faster than that of the HTPB propellant. These results are encouraging and suggest that it should be possible to improve the ballistic performance of popular HTPB propellants through use of the studied Nitro-HTPB binder.
      PubDate: 2017-03-06T03:10:24.882634-05:
      DOI: 10.1002/prep.201600120
       
  • Statistics of Density, Temperature and Air Gaps on the TATB Cylinder Test
    • Authors: P. Clark Souers; Lisa Lauderbach, Franco Gagliardi, Clif Mortensen
      Abstract: Duplicate cylinder tests (CYLEX) have been run on PBX 9502 and LX-17. The 95 % error in the absolute value of the derived detonation energy density is about ±1 % whereas the 95 % error of the difference error is ±0.5 % or better. The analytic model has been upgraded with a better strain description. The effect of the air gap between a pressed solid explosive and the inner copper wall has been measured and modeled. An off-center effect has also been seen. Density effects on the energy density from 1.82 to 1.92 g cm−3 are described for LX-17. Data has also been taken at −55, 75 and 125 °C. The last temperature gives a large enough difference to show that the mechanism appears to be only density change.
      PubDate: 2017-03-02T08:25:28.199103-05:
      DOI: 10.1002/prep.201700007
       
  • Comparison of Performance of Fast–reacting Nanothermites and Primary
           Explosives
    • Authors: Boris Khasainov; Marc Comet, Bernard Veyssiere, Denis Spitzer
      Abstract: The main features of nano-sized thermites are reviewed with the purpose to compare the performance of most reactive nanothermites showing high combustion front velocities of up to 2500 m s−1 with that of primary explosives. Because these regimes do propagate only at very low relative density of nano-thermites and as convective burning waves rather than detonations, the initiating capacity of these nanocompositions, compared to promises, is yet much lower than that of the primary explosives. Hybrid mixtures of nanothermite with high explosive offer practically interesting triggering potential and present a more promising way for substituting lead-based “not green” primary explosives. A threshold size of nanothermite particles is evaluated above which the dynamics of flame propagation in nanothermites can be reasonably described based on the principles of continuum mechanics and classical thermodynamics.
      PubDate: 2017-02-28T03:35:32.446559-05:
      DOI: 10.1002/prep.201600181
       
  • Research on Feasibility of Several High Density Materials for EFP Liner
           and Material Selection Criteria
    • Authors: Li Ding; Jianwei Jiang, Jianbing Men, Shuyou Wang, Mei Li
      Abstract: In order to find new kinds of EFP liner materials with high density, W alloys, Ni, Mo, U, and U alloy were selected to be tested. Both liner test and flyer plate test were carried out in experiment, with existing EFP liner materials being testified as reference. It turned out that among the selected materials only Ni was suitable for EFP liner material, other potential candidates fractured to different extent in experiment. The potential reasons of materials’ fracturing under explosive loading were analyzed through different scales in fracture mechanics. Characteristics of a feasible candidate material for EFP liner were discussed through fracture toughness KIC, impact toughness αk, damage tolerance dy, and microstructure mechanics analysis. Finally material selection criteria of EFP liner were presented. The research results are significant in the material selection of EFP liner especially within high density materials, and it can be important guidelines for the researchers to avoid the blindness in research investments and waste in experiments in EFP research field.
      PubDate: 2017-02-27T08:36:05.628196-05:
      DOI: 10.1002/prep.201600141
       
  • Experimental Study on Impact–induced Initiation Thresholds of
           Polytetrafluoroethylene/Aluminum Composite
    • Authors: Chao Ge; Yongxiang Dong, Wubuliaisan Maimaitituersun, Yuming Ren, Shunshan Feng
      Abstract: Impact experiments were conducted with a gas gun to investigate the impact-induced initiation thresholds of a polytetrafluoroethylene/aluminum (73.5 wt % and 26.5 wt %) composite. Targets of steel, aluminum, and low-density polyethylene materials and sample rods of four different lengths were used to decouple the effects of impact pressure and loading strain rate. By subjecting the samples to different loading conditions, it was shown that the impact-induced initiation of polytetrafluoroethylene/aluminum is decided by the impact pressure and the loading strain rate simultaneously. The impact pressure and strain-rate thresholds for initiation were arrested by the experiments. A 30° inclined steel target was used to produce a compression-shear configuration as a comparison with the normal impact experiments. The initiation was more likely to happen; it demonstrated a shear-induced initiation mechanism, and a lower initiation strain-rate threshold was observed under oblique impact. Based on the experimental results, two theoretical curves were proposed to predict the impact-induced initiation of polytetrafluoroethylene/aluminum under normal and 30° oblique impact.
      PubDate: 2017-02-27T08:35:43.548825-05:
      DOI: 10.1002/prep.201600216
       
  • Kinetic Parameters of PBX Based on
           Cis-1,3,4,6-tetranitroocta-hydroimidazo-[4,5-d] imidazole Obtained by
           Isoconversional Methods using Different Thermal Analysis Techniques
    • Authors: Ahmed Elbeih; Mohamed Abd-Elghany, Thomas M. Klapötke
      Abstract: The thermal decomposition kinetics of the interesting polycyclic nitramine cis-1,3,4,6-tetranitrooctahydroimidazo-[4,5-d]imidazole (BCHMX) and its polymer bonded explosive (PBX) based on polyurethane matrix, have been investigated using different thermal analysis techniques and methods. The used polyurethane matrix is based on hydroxyl-terminated polybutadiene (HTPB) cured by hexamethylene diisocyanate (HMDI). Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used nonisothermally, whereas the vacuum stability test (VST) was used isothermally. Kinetic parameters were determined by using isoconversional (model-free) methods. Furthermore, the Advanced Kinetics and Technology Solution (AKTS) software was used to determine the kinetic parameters of the studied samples in order to provide a comparison. It was found that the decomposition temperature of BCHMX/HTPB is lower than that of pure BCHMX. All the applied techniques as well as computational results showed that BCHMX/HTPB has a lower activation energy than pure BCHMX. The different methods used, Kissinger, Ozawa, Flynn, and Wall (OFW) and Kissinger-Akahira-Sunose (KAS) methods presented activation energies in the same range of the AKTS software results. Also the results proved that VST technique could be a useful tool to present results suitable for calculation of the kinetic parameters of explosives.
      PubDate: 2017-02-24T09:10:52.371885-05:
      DOI: 10.1002/prep.201700032
       
  • Glycidyl Azide–butadiene Block Copolymers: Synthesis from the
           Homopolymers and a Chain Extender
    • Authors: Sara Filippi; Leonardo Mori, Miriam Cappello, Giovanni Polacco
      Abstract: Glycidyl azide polymer (GAP) is an “energetic” alternative to hydroxyl-terminated polybutadiene (HTPB), but has poorer mechanical properties. Since HTPB-GAP mechanical blends are markedly biphasic, the use of block copolymers may be the solution to join the advantages of both. The copolymers were synthesized from the homopolymers by using two chain extenders: hexamethylene diisocyanate (HDI) and adipoyl chloride (AdCl). Both reagents gave homogeneous and stable polymeric mixtures, but with HDI there are risks of gelation during reaction. Therefore, the product obtained with AdCl is the best candidate to be used as binder or as compatibilizer in GAP-HTPB mechanical blends.
      PubDate: 2017-02-24T06:00:29.918171-05:
      DOI: 10.1002/prep.201600263
       
  • Influence of Anvil Properties on RDX Thin Layer Ignition Behavior
    • Authors: Otmar Yakaboski; Ashok V. Kumar
      Abstract: We report on a drop-impact protocol that arrests sample radial flow to isolate how anvil properties influence ignition in a thin layer of RDX powder. To eliminate sliding friction as a probable heating mechanism, flow arrestment was provided by a waxed weighing paper that shielded the RDX layer from direct contact with the impact surfaces. RDX reaction sensitivity under bare and shielded conditions for the standard O1 hardened steel anvil was compared with that for two deformable anvil types: 1018 steel and C110 copper. Profilometer measurements of anvil deformation and paper impressions quantified anvil plastic work and final radial flow displacement. Post-test particle analyses correlated particle size distribution to ignition results. Experiments indicated that the impact energy absorbed by the anvils was varied and inhibited ignition accordingly. For the standard anvil, ignition was not inhibited under flow arrestment, suggesting that significant radial sliding or flow is not essential for thin layer ignition.
      PubDate: 2017-02-23T08:05:30.071663-05:
      DOI: 10.1002/prep.201600301
       
  • Effect of Bonding Agent on the Mechanical Properties of GAP High-Energy
           Propellant
    • Authors: Jingke Deng; Xiaoqing Wang, Guoping Li, Yunjun Luo
      Abstract: Three kinds of bonding agent were chosen to improve the mechanical properties of GAP high-energy composite propellant based on GAP, BuNENA, HMX, AP, and Al. These bonding agents are N,N′-bis(2-hydroxyethyl) dimethylhydantoin and 1,3,5-trisubstituted isocyanurates (BA1), cyano-hydroxylated amines (BA2), and hyperbranched polyether with terminal groups substituted by hydroxyl, cyano and ester functional groups (BA3). To study the interaction between bonding agents and oxidizers, the effect of coating by bonding agents on the characteristic absorption peaks of AP and HMX were first studied by infrared spectroscopy. Then the effect of bonding agents on the adhesion work between oxidizers and binder system were determined. The results showed that BA2 has the strongest interaction with AP, whereas BA1 and BA3 have relatively strong interaction with HMX. The AP grain coated by BA2 has the strongest adhesion work to the binder system, and there is not much difference in the values of adhesion work towards binder system of three coated HMX grains. At last the three bonding agents were added to GAP propellant, which has a theoretical specific impulse of 276.03 s. When the three kinds of bonding agent was used alone, the sense of “dewetting” in propellant was relieved but still existed. The combination of BA2 to BA1 or BA3 improved the adhesions between oxidizers and binder system effectively, and the mechanical properties of GAP propellant reached to δm=0.69 MPa, ϵb=32.7 %.
      PubDate: 2017-02-23T02:40:23.083223-05:
      DOI: 10.1002/prep.201600123
       
  • The Correlation between Chemical Stability and Binder Network Structure in
           NEPE Propellant
    • Authors: Wan'e Wu; Chen Chen, Xiao Fu, Chao Ding, Guang Wang
      Abstract: The correlation between chemical stability and binder network structure is investigated to explore the aging mechanism of NEPE propellant. Through 70 °C aging storage experiments, propellant samples of different aging time periods are obtained every 7 days. The relative contents of MNA, NG, and BTTN are measured as the characteristic parameters of chemical stability. Gel fractions and cross-linking densities are detected as the characteristic parameters of binder network structure properties. Experimental results show that: (1) MNA content decreases slowly from 0 to 35 days and has a quadratic function relationship with time, then quickly drops linearly from 36 to 77 days, and the contents of NG and BTTN decrease as cubic function relationships with time. When aging to 56 days, the chemical stability of propellant becomes worse; (2) the gel fraction and cross-linking density increase at first, then decrease as time lapses, the decline rate of gel fraction and cross-linking density increase after 67 days and 63 days, respectively; and (3) the aging of structural performance lags behind the aging of chemical stability. The network structure parameters decrease logarithmically with MNA content, and the contents of nitrate esters have quadratic function relationships with gel fraction and cubic function relationships with cross-linking density. In summary, excellent chemical stability plays a positive role in maintaining good network structure in the process of propellant storage.
      PubDate: 2017-02-22T07:31:00.238123-05:
      DOI: 10.1002/prep.201600117
       
  • The Mechanical Properties of Minimally Processed RDX
    • Authors: Matthew R. Taw; David F. Bahr
      Abstract: We report for the first time the mechanical properties of RDX crystals in a conventionally processed, sub-millimeter form that have had no additional mechanical processing. Nanoindentation of RDX powders was used to measure the elastic modulus (19.1±1.9 GPa), hardness (0.741±0.098 GPa), and yield point (onset of plastic deformation) on the as-grown faces of seven different RDX crystals, selected to provide random orientations. Properties within each crystal showed narrow distributions, while the range of properties across all crystals is indicative of testing a variety of orientations. The elastic modulus and hardness are within the range of other published reports on bulk and mechanically polished RDX. The distribution in yield point behavior, with the onset of plasticity occurring between 0.1 and 0.7 GPa, indicates that powders of RDX likely contain a significant number of dislocation sources in the as-processed condition, suggesting that deformation sources are prevalent in the energetic component of plastic bonded explosives prior to incorporating into pressed forms.
      PubDate: 2017-02-22T07:26:51.632859-05:
      DOI: 10.1002/prep.201600143
       
  • Thermal Decomposition Research on 1,5-Diazabicyclo[3.1.0] Hexane (DABH) as
           a Potential Low-toxic Liquid Hypergolic Propellant
    • Authors: Xing Zhang; Lianhua Shen, Rongpei Jiang, Haiyun Sun, Tao Fang, Zhaoyang Liu, Jiuzhou Liu, Huili Fan
      Abstract: 1,5-Diazabicyclo[3.1.0] hexane (DABH) was found a potential hypergolic liquid propellant. The physical and energetic properties of DABH, 2-(dimethylamino) ethyl azide (DMAZ), and monomethyl hydrazine (MMH) were compared. The ignition delay time of DABH with nitrogen tetroxide was 1 ms, which was shorter than DMAZ and similar with MMH. The toxicology experiment showed that half lethal dose (LD50) of DABH was 621.0 mg kg−1, which suggested that DABH was promising to be used as low-toxic liquid propellant. Thermal decomposition experiments showed that the apparent activation energy (E) was about 66.3 kJ mol−1. The thermal decomposition calculated results from Madhusudanan-Krishnan-Ninan integration, Satava-Sestak integration and Achar differential methods were compared and the pre-exponential factor were obtained.
      PubDate: 2017-02-22T07:26:45.209265-05:
      DOI: 10.1002/prep.201600125
       
  • Thermal Decomposition Behaviors and Burning Characteristics of Ammonium
           Nitrate/Polytetrahydrofuran/Glycerin-based Composite Propellants
           Supplemented with MnO2 and Fe2O3
    • Authors: Makoto Kohga
      Abstract: Although a polytetrahydrofuran (PTHF) blend with added glycerin as a crosslinking modifier is an effective binder for improving the performance of a propellant, a burning catalyst is required for the combustion of the ammonium nitrate (AN)/PTHF/glycerin propellant. MnO2 and Fe2O3 are useful burning catalysts for AN-based propellants. The thermal decomposition behaviors of the AN/PTHF/glycerin propellant supplemented with MnO2 and Fe2O3 catalysts, and the catalytic effect of these catalysts on the burning characteristics was investigated in this study. The thermal decomposition behaviors of these propellants depended on the kind of catalyst used. The propellants containing MnO2 burned above 4 MPa, while those containing Fe2O3 burned above 0.5 MPa. The burning rate increased in the order, (AN/PTHF/Fe2O3)
      PubDate: 2017-02-22T04:40:33.902431-05:
      DOI: 10.1002/prep.201700014
       
  • Smokeless GAP-RDX Composite Rocket Propellants Containing
           Diaminodinitroethylene (FOX-7)
    • Authors: Tomas L. Jensen; Erik Unneberg, Tor E. Kristensen
      Abstract: Composite rocket propellants prepared from nitramine fillers (RDX or HMX), glycidyl azide polymer (GAP) binder and energetic plasticizers are potential substitutes for smokeless double-base propellants in some rocket motors. In this work, we report GAP-RDX propellants, wherein the nitramine filler has been partly or wholly replaced by 1,1-diamino-2,2-dinitroethylene (FOX-7). These smokeless propellants, containing 60% energetic solids and 15% N-butyl-2-nitratoethylnitramine (BuNENA) energetic plasticizer, exhibited markedly reduced shock sensitivity with increasing content of FOX-7. Conversely, addition of FOX-7 reduced the thermochemical performance of the propellants, and samples without nitramine underwent unsteady combustion at lower pressures (no burn rate catalyst was added). The mechanical characteristics were quite modest for all propellant samples, and binder-filler interactions improved slightly with increasing content of FOX-7. Overall, FOX-7 remains an attractive, but less than ideal, substitute for nitramines in smokeless GAP propellants.
      PubDate: 2017-02-22T04:40:26.956207-05:
      DOI: 10.1002/prep.201600278
       
  • Facile Preparation of AP/Cu(OH)2 Core-Shell Nanocomposites and Its Thermal
           Decomposition Behavior
    • Authors: Gazi Hao; Jie Liu, Qiaoe Liu, Lei Xiao, Xiang Ke, Han Gao, Ping Du, Wei Jiang, Fengqi Zhao, Hongxu Gao
      Abstract: Ammonium perchlorate (AP)/Cu(OH)2 core-shell nanocomposites were successfully synthesized using a facile ultrasonic assisted-coprecipitation synthesis route. The obtained AP/Cu(OH)2 nanocomposites were characterized by means of powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Its thermal decomposition was studied under the non-isothermal conditions with thermogravimetric analysis and differential scanning calorimeter (TG-DSC) techniques. In this procedure, SEM and TEM observations revealed that Cu(OH)2 nanoparticles with an average size of 10–15 nm were uniformly deposited on the surface of AP particles. Detailed characterization results indicated that the existence of evidence of Cu(OH)2. As expected, it was found that the AP/Cu(OH)2 nanocomposites with mass fraction of 2 wt % Cu(OH)2 remarkably decreased the peak temperature of high temperature decomposition of AP by 80.2 °C from approximately 441.3 °C to 361.1 °C. As compared with pure AP, the AP/Cu(OH)2 nanocomposites show lower impact and friction sensitivity. These results may lead to potential applications of the AP/Cu(OH)2 nanocomposites in the composite solid propellants for accelerating the thermal decomposition of AP.
      PubDate: 2017-02-22T04:35:24.627274-05:
      DOI: 10.1002/prep.201600209
       
  • Numerical Study on Thermal Safety of Emulsion Matrix in Emulsifier
    • Authors: Li Qiong Wang; Yi Bo Zhang
      Abstract: The purpose of this study is to research the effect of high speed stirring by emulsifier blades on the thermal safety of emulsion matrix. In order to analyze thermal safety of emulsion matrix in emulsifying process, the heating effect influenced by rotor speed and emulsify temperature was combined with self-heat properties of emulsion matrix in this study. Computational fluid dynamics (CFD) is used for analysis. The emulsifier model adopts simplified CYJ type emulsifier, which is a kind of vertical emulsifier and has a large stirring area. The self-heat properties of emulsion matrix are described by Arrhenius equation. The simulation results showed that heat could not accumulate in emulsion matrix due to the strong turbulence formed by stirring. But, because of the shear stress and friction, a high temperature region will be formed around the blades of the rotor in a short time. If the stirring speed reaches 10300 rpm, the temperature in this region would be able to reach the critical ignition temperature of emulsion matrix.
      PubDate: 2017-02-22T04:30:49.439143-05:
      DOI: 10.1002/prep.201600198
       
  • Estimated Detonation Velocities for TKX-50, MAD-X1, BDNAPM, BTNPM, TKX-55,
           and DAAF using the Laser-induced Air Shock from Energetic Materials
           Technique
    • Authors: Jennifer L. Gottfried; Thomas M. Klapötke, Tomasz G. Witkowski
      Abstract: Since new energetic materials are initially produced in very small quantities for both safety and cost reasons, laboratory-scale methods for characterizing their performance are essential for determining the most promising candidates for scale-up. Laser-induced air shock from energetic materials (LASEM) is a promising new method for estimating the detonation velocity of novel explosives using milligram amounts of material, while simultaneously investigating their high temperature chemical reactions. LASEM has been applied to 6 new explosives for the first time: TKX-50, MAD-X1, BDNAPM, BTNPM, TKX-55, and DAAF. Emission spectroscopy of the laser excited materials revealed the formation of the high pressure bands of C2 during the ensuing exothermic reactions. The low thermal sensitivity of the materials also led to unusual laser-material interactions, visualized with high-speed video. The estimated detonation velocities for the 6 explosives were compared to predicted values from EXPLO5 and CHEETAH. The LASEM results suggest that TKX-55, BDNAPM, and BTNPM have higher detonation velocities than predicted by the thermochemical codes, while the estimated detonation velocities for MAD-X1 and TKX-50 are slightly lower than those predicted.
      PubDate: 2017-02-21T09:42:17.874472-05:
      DOI: 10.1002/prep.201600257
       
  • Synthesis and Characterization of New Calixarenes Containing Explosives
           with High Temperature Stabilities
    • Authors: Xingcheng Zhang; Hualin Xiong, Hongwei Yang, Guangbin Cheng
      Abstract: A few of novel, thermally stable, nitro-substituted calixanes were successfully synthesized and their spatial configurations also were confirmed. 14,16,34,36,54,56,74,76-octanitro-2,4,6,8-tetraoxa-1,3,5,7(1,3)-tetraben-zenacyclooctaphane (7) as heat-resistant explosives can be prepared by means of a facile synthetic produced and shows outstanding properties (good thermal stability and high thermal decomposition temperature and energetic performances). It has also been pointed out that the production of compound 7 is very easy on a large scale. All target compounds was characterized by single-crystal X-ray diffraction, NMR and elemental analysis, TG and DSC. In this paper, the macrocyclic compounds are introduced into the study as heat-resistant explosives firstly, which will change the past stagnant situation!
      PubDate: 2017-02-21T02:35:34.523945-05:
      DOI: 10.1002/prep.201700030
       
  • Iodine Pentoxide Nano-rods for High Density Energetic Materials
    • Authors: Mkhitar A. Hobosyan; Karen S. Martirosyan
      Abstract: The iodine pentoxide is one of the most advanced oxidizers for nanostructured energetic formulations among the thermites due to the highest energy release per volume 25.7 kJ cm−3. The size and shape of iodine pentoxide particles have a strong impact on the pressurization rates during the reaction. Although micro-sized iodine pentoxide particles are commercially available, nano-sized particles, which are desired for various nano-energetic applications, are not available on the market. Conventional wet chemical methods are unable to produce iodine pentoxide nanoparticles due to high solubility in water. In this study, we demonstrate fabrication of iodine pentoxide nano-rods by high energy mechanical treatment of micro-sized I2O5 particles. Tuning the energy dose in high-energy ball milling is allowing to produce I2O5 nano-rods with diameter of 50–100 nm and length of 300–600 nm. The produced nano-rods exhibited 10 % smaller decomposition energy compared to the precursor of micro particles. The experiments showed that the nano-energetic materials prepared with nano-sized I2O5 rods have pressure discharge value of 43.4 MPa g−1 which is two times higher than using commercial iodine pentoxide particles.
      PubDate: 2017-02-20T09:35:27.200606-05:
      DOI: 10.1002/prep.201600220
       
  • Experiments and Numerical Calculations on Laser-induced Ignition of Single
           Micron-sized Aluminum Fuel Particle
    • Authors: Shengji Li; Xuefeng Huang, Donghui Zhou
      Abstract: This paper presents the experiments and numerical calculations on the laser-induced ignition of single micron-sized aluminum particle in an atmospheric pressure air flow at low Reynolds number. Experimental results demonstrate that the radiation intensity of single micron-sized aluminum particle, during ignition, experiences first sharp rising, stable equilibrium and second steep rising stages. A simplified analytical model was built and numerically solved. Numerical results show that the three distinctive stages represent the heating, melting and evaporation, respectively. Laser radiation mainly contributes to heat aluminum particle, leading to phase transition (melting). The heat released from heterogeneous surface reaction (HSR) dominates the temperature rise of the liquid aluminum and accelerate its evaporation. During ignition, the heat loss of natural convection significantly affects the ignition performance of aluminum particle, while the heat loss of radiation toward the surrounding air only affects the evaporation rate. Threshold ignition energy of aluminum particle based on numerical calculations is in good agreement with the experiments, which strongly depends on the particle diameter. Ignition delay time depends on the particle diameter and ignition energy. This study will be beneficial to deeply recognize the ignition mechanism of single micron-sized aluminum particle, especially in the transition region between nanoscale and microscale.
      PubDate: 2017-02-20T07:15:43.654377-05:
      DOI: 10.1002/prep.201600215
       
  • An Efficient Method for Determination of the Diphenylamine (Stabilizer) in
           Propellants by Molecularly Imprinted Polymer based Carbon Paste
           Electrochemical Sensor
    • Authors: Pankaj E. Hande; Asit B. Samui, Prashant S. Kulkarni
      Abstract: In this work we report efficient molecularly imprinted polymer (MIP) based carbon paste electrode sensor for the determination of diphenylamine in aged propellant. Initially, diphenylamine (DPA)-MIP was synthesized by using methacrylic acid (monomer) and ethylene glycol dimethyacrylate (cross-linker). Developed DPA-MIP was analyzed by Fourier transform infrared spectroscopy and Field-emission scanning electron microscopy. The sensor was incorporated as electrode in cyclic voltammetry. The sensor response was linear in the range of 0.5–3 mM DPA concentration. The lower detection limit obtained for sensor was 0.1 mM. The developed sensor was used for the determination of DPA in propellant systems. Same electrode was used for three repeated analysis without significant decrease in efficiency.
      PubDate: 2017-02-20T07:15:37.977715-05:
      DOI: 10.1002/prep.201600118
       
  • Partial Reparametrization of the BKW Equation of State for DNAN-Based
           Melt-Cast Explosives
    • Authors: Dongwei Li; Lin Zhou, Xiangrong Zhang
      Abstract: DNAN-based melt-cast explosives are a type of new, insensitive munitions (IM) explosives. Quickly determining munitions’ explosive properties is extremely important during the formulation design stage. The aim of this study was to partially reparameterize BKW-EOS (only β and κ were reparameterized on the basis of the parameters (α, β, κ, and θ) of classical BKW-RDX set and BKW-TNT set) to more accurately predict the properties of DNAN-based melt-cast explosives. A new set of parameters β and κ was obtained (β=0.19, κ=9.81) according to measured detonation velocity and detonation pressure for ideal DNAN-based melt-cast formulations (DNAN/RDX and DNAN/HMX). For non-ideal DNAN-based melt-cast formulations (DNAN/RDX/Al and DNAN/HMX/Al), aluminum oxidation degree was first determined according to the measured detonation heat; then, another new set of parameters β and κ was obtained in the same way as the ideal formulations (β=0.24, κ=8.5). The predicted detonation properties with BKW reparametrization for DNAN-based melt-cast explosives agreed with the measured data.
      PubDate: 2017-02-20T07:15:34.403625-05:
      DOI: 10.1002/prep.201600206
       
  • Effect of Pre-strain Aging on the Damage Properties of Composite Solid
           Propellants based on a Constitutive Equation
    • Authors: Dongmo Zhou; Xiangyang Liu, Xin Sui, Zhijun Wei, Ningfei Wang
      Abstract: Accelerated aging tests under pre-strain were conducted on HTPB-based composite solid propellant with the goal of investigating the effect of pre-strain aging on its damage properties. A statistical damage constitutive model based on continuum damage theory and statistical strength theory was established. The aging damage coefficient, making aging process of propellant equivalent to a form of damage, was introduced to correct the damage variable. Experimental results show that theoretical model has good agreement with experimental results and can accurately describe the mechanical behavior of propellant during pre-strain aging. Further analysis indicated that the damage effects caused by pre-strain can be identified from the equation of the aging damage coefficient. Aging time influences both tensile strength and shape characteristics of the stress-strain curve of propellant in the damage stage, while pre-strain only decreased the tensile strength. The strain damage threshold value decreased linearly over the aging period and with increasing pre-strain level during the aging process.
      PubDate: 2017-02-20T07:15:29.222273-05:
      DOI: 10.1002/prep.201600128
       
  • Generation and Evolution of Surface Oxide Layer of Amorphous Boron during
           Thermal Oxidation: A Micro/nanofabricated Slice Measurement
    • Authors: Daolun Liang; Jianzhong Liu, Heping Li, Junhu Zhou, Kefa Cen
      Abstract: The generation and evolution of the surface oxide layer of boron were thoroughly investigated due to the key role of the oxide layer in ignition and combustion of amorphous boron (B). Samples in different oxidation degrees were obtained by heating B particles until 600, 650, and 700 °C, using a temperature programmed thermobalance. A dual beam focused ion beam micro/nanofabricator was used to etch and cut the samples into thin slices (ca. 327 nm). The slices were observed under a scanning transmission electron microscope, accompanied with energy dispersive X-ray analysis. During the thermal oxidation process, B particles initially lost mass through dehydration. Then they began to get oxidized and gain weight markedly. The sample surface became more rough as the final temperature increased. Two different reaction modes took place in sequence during the thermal oxidation of the samples. Below 650 °C, the oxidation reaction occurred only on the surface of the particle (the surface reaction mode). However, when the samples were heated to 700 °C, the particle interior was also involved in the reaction (the global reaction mode), and a large number of pores were formed. The O content of the initial surface oxide layer was fairly high. The thickness distribution was uniform (average thickness 148.1 nm) and the two edges were both smooth. During the heating, the oxygen content of the surface oxide layer increased after an initial decrease. The average oxide layer thickness increased and the thickness distribution became irregular and unequal. The sample heated until 700 °C had an average surface oxide layer thickness of 379.3 nm, and the thickness span reached 354.3 nm. During the global reaction process (700 °C), the oxidation degree within the interior of the particle was lower than that on its surface. In the particle interior, pores near the center were smaller than those close to the edge, whereas the oxidation degree was uniformly distributed. Results in this work provide a deeper understanding of the surface oxide layer, which can potentially help improve the ignition and combustion features of B.
      PubDate: 2017-02-20T07:10:33.782789-05:
      DOI: 10.1002/prep.201600221
       
  • Efficient Sensitivity Reducing and Hygroscopicity Preventing of Ultra-fine
           Ammonium Perchlorate for High Burning-rate Propellants
    • Authors: Zhijian Yang; Feiyan Gong, Ling Ding, Yubin Li, Guangcheng Yang, Fude Nie
      Abstract: In this research, several inert materials, including some functional carbon materials, paraffin wax and the well-known insensitive energetic material 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) were selected to reduce the undesirable high sensitivity and hygroscopicity of ultra-fine ammonium perchlorate (UF-AP) via polymer modified coating. Structure, sensitivity, thermal and hygroscopicity performances of the UF-AP based composites were systematically studied by scanning electron microscopy, sensitivity tests, thermal experiments, contact angle, and hygroscopicity analysis. The results showed that both the impact and friction sensitivity of UF-AP can be remarkably reduced, respectively, with only a small amount of 2 % (in mass) desensitization agents. Meanwhile, improved thermal decomposition was gained, and the hygroscopicity can also be reduced to a large extent. Propellants containing 10 % coated UF-AP in mass were processed and tested, the burning rate reached 45.7 mm s−1, 50 % higher compared with that of normal AP, with remarkably reduced impact sensitivity from 11.5 J to 29.6 J and friction sensitivity from 76 % to 28 %.
      PubDate: 2017-02-20T07:10:27.805997-05:
      DOI: 10.1002/prep.201600237
       
  • Introducing Novel Tetrazole Derivatives as High Performance Energetic
           Compounds for Confined Explosion and as Oxidizer in Solid Propellants
    • Authors: Mohammad Hossein Keshavarz; Yasin Hayat Abadi, Karim Esmaeilpour, Sajjad Damiri, Mohsen Oftadeh
      Abstract: This paper introduces five novel high-nitrogen content (N>50 %) tetrazole derivatives with desirable physicothermal properties, high detonation and combustion performance as well as suitable sensitivities with respect to external stimuli electric spark and heat. Suitable density functional theory (DFT) and empirical methods were used to predict their crystal density, melting point, condensed phase heat of formation, enthalpy of fusion, Gibbs free energy of formation, velocity of detonation, detonation pressure, Gurney velocity, heat of detonation, power (strength), brisance, impact sensitivity, electric spark sensitivity, heat sensitivity and specific impulse. Two compounds 5,5′-[(1Z,5Z)-3,4-dinitrohexaaza-1,5-diene-1,6-diyl]bis(1-nitro-1H-tetrazole) and 3,3′,7,7′-tetranitro-3,3a,3′,3′a-tetrahydro-7H,7′H-6,6′-bitetrazolo[1,5-e]pentazine as compared to the other new derivatives can be introduced as high performance explosives for confined explosion and oxidizers in solid propellants.
      PubDate: 2017-02-20T07:10:23.179551-05:
      DOI: 10.1002/prep.201600249
       
  • Evaluation of 4-(Dimethylsilyl) Butyl Ferrocene Grafted HTPB as a Burning
           
    • Authors: Ramesh Kurva; Garima Gupta, Kashinath I. Dhabbe, Lalita S. Jawale, Prasanth S. Kulkarni, Mehilal Maurya
      Abstract: High burning rate composite propellants are achieved by incorporation of fine particles of oxidizer, transition metal oxides, and liquid ballistic modifiers. However, they pose processing problems, inertness to the composition and migration related issues. To overcome such problems, an attempt was made to incorporate ferrocenyl grafted HTPB as a burning rate modifier by partly replacing HTPB from 10 % to 50 % using TDI/ IPDI bicurative system and to study their processability in terms of viscosity, mechanical, thermal, sensitivity, and ballistic properties. The data on viscosity reveal that there is a marginal enhancement in end of mix viscosity as percentage of ferrocenyl grafted HTPB increases. The mechanical data reveal that tensile strength and elastic modulus increases, whereas percentage elongation decreases compared to base composition. The results on thermal properties infer that, as the percentage of ferrocenyl grafted HTPB increases, onset decomposition temperature decreases. The impact and friction sensitivity data also envisage that sensitivity increases in comparison to base composition. The data on ballistic properties revealed that there is ca. 53 % increase in burning rate, while decrease in “n” value from 0.39 to 0.2 was obtained compared to base composition.
      PubDate: 2017-01-03T06:35:57.173727-05:
      DOI: 10.1002/prep.201600178
       
  • Assessment of Physico-Thermal Properties, Combustion Performance, and
           Ignition Delay Time of Dimethyl Amino Ethanol as a Novel Liquid Fuel
    • Authors: Shahram G. Pakdehi; Mohammad Hossein Keshavarz, Maryam Akbari, Mostafa Ghorbani
      Abstract: Dimethyl amino ethanol (DMAE) contains both hydroxyl and amino functional groups, which may be introduced as a new liquid fuel with high safety and less toxicity with respect to common high performance liquid fuels. Physico-thermal properties, combustion performance and ignition delay time of DMAE are compared with the usual high performance liquid fuels as well as ethanol and dimethylamine. Combustion performances of DMAE (specific impulse at sea level) with common liquid oxidizers including white fuming nitric acid (WFNA), inhibited red fuming nitric acid (IRFNA), nitrogen tetroxide (N2O4), hydrogen peroxide (H2O2), liquid oxygen (LOX), and the mixed oxides of nitrogen (MON) are also evaluated. Maximum and minimum specific impulses of DMAE are obtained with LOX (299.6 s) and WFNA (262.4 s), respectively. Maximum density-specific impulse is obtained with DMAE-N2O4 bipropellant. The ignition delay time of DMAE with several liquid oxidizers are measured with open cup test method. DMAE-WFNA and DMAE-IRFNA bipropellants are hypergolic where their ignition delay times are 26 and 42 milliseconds, respectively.
      PubDate: 2017-01-03T06:35:53.960144-05:
      DOI: 10.1002/prep.201600113
       
  • Cover Picture: Estimated Detonation Velocities for TKX-50, MAD-X1, BDNAPM,
           BTNPM, TKX-55, and DAAF using the Laser–induced Air Shock from Energetic
           Materials Technique (Prop., Explos., Pyrotech. 4/2017)
    • Authors: Jennifer L. Gottfried; Thomas M. Klapötke, Tomasz G. Witkowski
      Pages: 345 - 345
      Abstract: The cover picture shows the excitation of TKX-55 and BTNPM with a focused laser pulse and their molecular structures; red = O, blue = N, gray = C, and white = H. Exothermic reactions of the energetic material increase the plasma temperature and a shock wave expands into the air above the sample. The first 3 snapshots from the high-speed video of the shock wave expansion are shown for each of the samples. The measured shock wave velocities were used to estimate the detonation velocities of the energetic materials. The emission spectra for each of the laser-excited samples are given on the right side of the picture; these spectra provide insight into the high-temperature chemical reactions. Details are discussed in the article by Jennifer L. Gottfried et al. on page 353.
      PubDate: 2017-04-18T08:44:55.314624-05:
      DOI: 10.1002/prep.201780401
       
  • Inside Cover: Effect of Organic Fluoride on Combustion Agglomerates of
           Aluminized HTPB Solid Propellant (Prop., Explos., Pyrotech. 4/2017)
    • Authors: Xuyuan Zhou; Meishuai Zou, Fenglei Huang, Rongjie Yang, Xiaoyan Guo
      Pages: 346 - 346
      Abstract: The inside cover picture shows the effect of organic fluoride on combustion agglomerates of aluminized HTPB solid propellants. The particle size of solid combustion products were sharply decreased and agglomerates were well-depressed, enhancement of γ-Al2O3 formation in the propellant combustion products and the release of small gaseous molecules by OF at high temperatures pushes organic fluoride great potential in depressing agglomeration. Details are discussed in the article by Xuyuan Zhou et al. on page 417.
      PubDate: 2017-04-18T08:44:52.769424-05:
      DOI: 10.1002/prep.201780402
       
  • Contents: Prop., Explos., Pyrotech. 4/2017
    • Pages: 347 - 349
      PubDate: 2017-04-18T08:44:54.542178-05:
      DOI: 10.1002/prep.201780411
       
  • Forthcoming Meetings: Prop., Explos., Pyrotech. 4/2017
    • Pages: 448 - 449
      PubDate: 2017-04-18T08:44:53.9108-05:00
      DOI: 10.1002/prep.201780498
       
  • Future Articles: Prop., Explos., Pyrotech. 5/2017
    • Pages: 451 - 451
      PubDate: 2017-04-18T08:44:52.820812-05:
      DOI: 10.1002/prep.201780499
       
  • Inside Back Cover: Research on Feasibility of Several High Density
           Materials for EFP Liner and Material Selection Criteria (Prop., Explos.,
           Pyrotech. 4/2017)
    • Authors: Li Ding; Jianwei Jiang, Jianbing Men, Shuyou Wang, Mei Li
      Pages: 455 - 455
      Abstract: The inside backcover picture shows how different scales of fracture mechanics can be used to analyze the fracture phenomenon in engineering. The picture also reflects the potential reasons of materials’ fracturing under explosive loading, through fracture toughness KIC, impact toughness ak, damage tolerance dy and microstructure mechanics analysis. Finally material selection criteria of EFP liner are presented. Details are discussed in the article by Li Ding et al. on page 360.
      PubDate: 2017-04-18T08:44:56.264505-05:
      DOI: 10.1002/prep.201780403
       
  • Back Cover: Smokeless GAP-RDX Composite Rocket Propellants Containing
           Diaminodinitroethylene (FOX-7) (Prop., Explos., Pyrotech. 4/2017)
    • Authors: Tomas L. Jensen; Erik Unneberg, Tor E. Kristensen
      Pages: 456 - 456
      Abstract: The back cover picture shows testing of a tactical rocket motor containing a smokeless composite rocket propellant – using RDX as energetic filler, glycidyl azide polymer (GAP) as energetic binder and N-butyl-2-nitratoethylnitramine (BuNENA) as energetic plasticizer – at the Nammo Raufoss Test Center in Norway. Replacement of RDX in such compositions with diaminodinitroethylene (FOX-7) results in propellants with markedly reduced shock sensitivity. Although the mechanical properties are retained, the specific impulse and the burn rate characteristics are adversely affected. Details are discussed in the article by Tomas L. Jensen et al. on page 381.
      PubDate: 2017-04-18T08:44:54.626226-05:
      DOI: 10.1002/prep.201780404
       
 
 
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