Showing papers in "Propellants, Explosives, Pyrotechnics in 2009"
TL;DR: In this article, Nanocrystalline transition metal oxides (NTMOs) have been successfully prepared by three different methods: novel quick precipitation method, surfactant mediated method and reduction of metal complexes with hydrazine as reducing agent (Mn2O3).
Abstract: Nanocrystalline transition metal oxides (NTMOs) have been successfully prepared by three different methods: novel quick precipitation method (Cr2O3 and Fe2O3); surfactant mediated method (CuO), and reduction of metal complexes with hydrazine as reducing agent (Mn2O3). The nano particles have been characterized by X-ray diffraction (XRD) which shows an average particle diameter of 35 – 54 nm. Their catalytic activity was measured in the thermal decomposition of ammonium perchlorate (AP). AP decomposition undergoes a two step process where the addition of metal oxide nanocrystals led to a shifting of the high temperature decomposition peak toward lower temperature. The kinetics of the thermal decomposition of AP and catalyzed AP has also been evaluated using model fitting and isoconversional method.
109 citations
TL;DR: In this article, spontaneous Raman spectroscopy was used to identify explosives at distances of up to 55 in using an outdoors test field and performing experiments under varying weather conditions such as rain or snowfall or bright sunshine.
Abstract: Standoff identification of explosives at distances of up to 55 in has been performed by applying spontaneous Raman spectroscopy. This work has been focused on detection in a realistic environment, using an outdoors test field and performing experiments under varying weather conditions such as rain- or snowfall or bright sunshine. The instrumentation, based on a 532 nm pulsed laser source combined with gated detection, proved the performance insensitive to weather variations. Investigated HMEs and precursors were TATP, HMTD, HP, MEKP, NM, NB, and IPN; all in bulk quantities. The time needed for acquiring spectra was typically between single pulse (5 ns) and 10 s. Detection through green and brown glass bottles and PET bottles were tried and found viable. (Less)
91 citations
TL;DR: The vapor signature of diacetone diperoxide (DADP) and hexamethylene triperoxide diamine (HMTD) were examined by a gas chromatography (GC) headspace technique over the range of 15 to 55°C as discussed by the authors.
Abstract: The vapor signature of diacetone diperoxide (DADP) and hexamethylene triperoxide diamine (HMTD) were examined by a gas chromatography (GC) headspace technique over the range of 15 to 55 °C. Parallel experiments were conducted to redetermine the vapor pressures of 2,4,6-trinitrotoluene (TNT) and triacetone triperoxide (TATP). The TNT and TATP vapor pressures were in agreement with the previously reported results. Vapor pressure of DADP was determined to be 17.7 Pa at 25 °C, which is approximately 2.6 times higher than TATP at the same temperature. The Clapeyron equation, relating vapor pressure and temperature, was LnP (Pa)=35.9−9845.1/T (K) for DADP. Heat of sublimation, calculated from the slope of the line for the Clapeyron equation, was 81.9 kJ mole−1. HMTD vapor pressure was not determined due to reduced thermal stability resulting in vapor phase decomposition products.
72 citations
TL;DR: In this paper, the authors examined the effect of nano-aluminum particles with fumed silica in terms of the deflagration and detonation characteristics of a mixture of nitromethane and aluminum.
Abstract: The heterogeneous interaction between nitromethane (NM), particles of nanoscale aluminum (38 and 80 nm diameter), and fumed silica is examined in terms of the deflagration and detonation characteristics. Burning rates are quantified as func- tions of pressure using an optical pressure vessel up to 14.2 MPa, while detonation structure is characterized in terms of failure diameter. Nitromethane is gelled using fumed silica (CAB-O- SIL � ), as well as by the nanoaluminum particles themselves. Use of nanoaluminum particles with fumed silica slightly increases burning rates compared to the use of larger diameter Al particles; however distinct increases in burning rates are found when CAB- O-SIL is removed and replaced with more energetic aluminum nanoparticles, whose high surface area allows them to also act as the gellant. Mixtures including fumed silica yield a reduced burning rate pressure exponent compared to neat NM, while mixtures of aluminum particles alone show a significant increase. Failure diameters of mixture detonations are found to vary significantly as a function of 38 nm aluminum particle loading, reducing more than 50% from that of neat nitromethane with 12.5% (by mass) aluminum loading. Failure diameter results indicate a relative minimum with respect to particle separation (% loading) which is not observed in other heterogeneous mixtures.
69 citations
TL;DR: In this article, a binder system based on the 1.3 dipolar cycloaddition reaction of azido groups with acetylene compounds forming 1,2,3-triazole heterocyclic rings has been applied for ADN/GAP and AP/gAP propellants.
Abstract: In this contribution two ways are described, how it is possible to achieve perfectly cured and processible propellants with prilled ADN, low amounts of HMX 5 μm mps and a binder system based on GAP diole and GAP triole oligomers with and without TMETN as a nitrate ester plasticizer. It was shown how it will be possible to suppress the strongly gas forming reaction between ADN and reactive isocyanates by a mixture of stabilizers. In this way it was possible to create minimum smoke ADN/HMX/GAP/TMETN propellants cured with the triisocyanate N100. In the second part an unconventional binder system based on the 1.3 dipolar cycloaddition reaction of azido groups with acetylene compounds forming 1,2,3-triazole heterocyclic rings has been applied for ADN/GAP and AP/GAP propellants. Together with small parts of HMX formulations with ADN/HMX/GAP and the corresponding AP/HMX/GAP exhibit high thermodynamic performance, are easily processible, and cure successfully at 60 °C. Their basic properties consisting of burning behavior and mechanical properties, at ambient temperature, chemical stability, and sensitivity have been investigated and are compared to each other.
65 citations
TL;DR: In this article, a coprecipitation method was used to obtain the average particle size by using Scherrer's equation for BTMF nanocrystals of formula MFe2O4 (M=Cu, Co, Ni) and characterized by X-ray diffraction.
Abstract: Binary transition metal ferrite (BTMF) nanocrystals of formula MFe2O4 (M=Cu, Co, Ni) were prepared by the coprecipitation method and characterized by X-ray diffraction (XRD). XRD patterns gave average particle size by using Scherrer's equation for CuFe2O4 (CuF), CoFe2O4 (CoF), and NiFe2O4 (NiF) as 39.9, 27.3, and 43.8 nm, respectively. The catalytic activity measurements on the thermal decomposition of ammonium perchlorate (AP) were carried out by using thermogravimetry (TG), differential thermal analysis (DTA), and ignition delay studies. Isothermal TG data up to a mass loss of 45% have been used to evaluate kinetic parameters by using model fitting as well as isoconversional method. The order of catalytic activity was found to be:
64 citations
TL;DR: In this article, bis-propargyl-succinate (BPS) was applied to four different GAP mixtures with di-and tri-functional GAP types.
Abstract: Four different GAP mixtures with di- and tri-functional GAP types were successfully cured with bis-propargyl-succinate (BPS) via 1,3 dipolar cycloaddition reaction between the azido groups of GAP and the triple bonds of the propargyl ester. Investigation of one series of curing on di-functional and another series on tri-functional GAP was done and compared with two additional curing series on mixtures of di- and tri-functional GAP. The BPS which acted as a curing agent analog to isocyanate in classical polyurethane systems, was varied in its content, and the influence on the mechanical properties of the cross-linked binders was measured by tensile tests. The mechanical properties could be adjusted in a wide range by varying the amount of BPS. The E modulus of the tested samples was in the range of 0.06–0.674 N mm−2 at elongations between 50 and 95% and the maximum stress was in the range of 0.05–0.32 N mm−2. Increasing contents of BPS showed, in thermal analysis by DSC, only a small decrease in the decomposition energy and slightly raised glass transition temperatures. The required amount of inert curing agent for complete cure of GAP is lower for BPS in comparison to isocyanate, so this will result in a higher total energy content in the binder system. However, BPS-cured systems can lead to higher glass transition temperatures than isocyanate-based binder systems. The curing process has been monitored by measuring the increasing viscosity at 50 and 60 °C. The curing time of the investigated binder systems for quantitative curing at 65 °C is around four days, which was checked by measuring the surface hardness, but at room temperature the premixed curing samples staid liquid for around 1 week.
59 citations
TL;DR: In this paper, the Al/Bi2O3 reaction generated the highest pressure pulse among the eight thermite reactions, and the maximum pressure×volume (PV) value obtained at m=0.02 ms and ΔP/Δt of up to 500 GPa s−1.
Abstract: Nanoenergetic gas-generator (NGG) mixtures may have various potential military applications from aircraft fuels to rocket propellants, explosives, and primers. To find reactions generating the highest pressure peak, we studied eight nanoenergetic reactions. The Al/Bi2O3 reaction generated the highest pressure pulse among the eight thermite reactions. We developed a highly efficient, one step process for synthesis of Bi2O3 nanostructured particles. Its use generated about a three times higher peak pressure (∼10 MPa) than when using commercial bismuth oxide nanoparticles (3 MPa). The pressure in the vessel rose very rapidly to a peak value for a duration of ∼0.02 ms and ΔP/Δt of up to 500 GPa s−1. Increasing the crystallinity of the bismuth oxide nanoparticles increased the peak gas pressure by 25%. The maximum pressure×volume (PV) value obtained at m=0.1 g with our synthesized Bi2O3 was 707 Pa m3 much higher than that reported in the literature (33 Pa m3) for the same sample mass. Addition of carbon to the reactant mixtures did not increase the peak pressure. Addition of up to 3 wt.-% of boron to the thermite systems increased the peak pressure by ∼50%.
56 citations
TL;DR: In this paper, the characteristics and performance evaluation of a pressed plastic bonded explosive (PBX) composition based on hexanitrohexaazaisowurtzitane (HNIW, CL-20) and polyurethane (PU) in comparison with PU-coated cyclotetramethylene tetranitramine (HMX) was reported.
Abstract: This paper reports the characteristics and performance evaluation of a pressed plastic bonded explosive (PBX) composition based on hexanitrohexaazaisowurtzitane (HNIW, CL-20) and polyurethane (PU) in comparison with PU-coated cyclotetramethylene tetranitramine (HMX). PU-coated compositions were prepared by slurry method. The processed CL-20-based composition exhibited a relatively higher sensitivity compared to that of the HMX composition. The measured velocity of detonation (VOD) of the CL-20-based composition was found to be higher than predicted. A theoretical approach was applied to assess the penetration capability of the CL-20 formulation. Shaped charges of 32 mm caliber were prepared and penetration experiments were carried out at 37 mm standoff distance on mild steel blocks. The results established high penetration capability of CL-20-based formulation. An attempt was made to explain the trends obtained.
54 citations
TL;DR: In this paper, a new model is derived to estimate the size and fraction of aluminum agglomerates at the surface of a burning propellant, based on well-known pocket models in which aluminum is supposed to aggregate and melt within pocket volumes imposed by largest oxidizer particles.
Abstract: A new model is derived to estimate the size and fraction of aluminum agglomerates at the surface of a burning propellant. The basic idea relies on well-known pocket models in which aluminum is supposed to aggregate and melt within pocket volumes imposed by largest oxidizer particles. The proposed model essentially relaxes simple assumptions of previous pocket models on propellant structure by accounting for an actual microstructure obtained by packing. The use of statistical tools from stochastic geometry enables to determine a statistical pocket size volume and hence agglomerate diameter and agglomeration fraction. Application to several AP/Al propellants gives encouraging results that are shown to be superior to former pocket models.
49 citations
TL;DR: In this article, experimental and computational results that explain some aspects of measured energy release in explosions of unconfined trinitrotoluene [TNT, C6H2(NO2)3CH3], and an aluminum-containing explosive formulation, and show how this energy release can influence shock wave velocities in air.
Abstract: We present experimental and computational results that explain some aspects of measured energy release in explosions of unconfined trinitrotoluene [TNT, C6H2(NO2)3CH3], and an aluminum-containing explosive formulation, and show how this energy release can influence shock wave velocities in air. In our interpretation, energy release is divided into early, middle, and late time regimes. An explanation is provided for the interdependence of the time regimes and their influence on the rate at which energy (detonation/explosion and afterburn) is released. We use a merging of the thermodynamic and chemical kinetic processes that predicts how chemical kinetics may determine the time delay of the afterburn of combustible gases produced by the initial detonation/explosion/fast reaction. The thermodynamic computer code CHEETAH is used to predict gaseous and solid products of early time energy release, and a chemical kinetic reaction mechanism (CHEMKIN format) is used to describe the subsequent afterburn of the gas phase products in air. Results of these calculations are compared with field measurements of unconfined explosions of 2 kg charge weights of TNT and an aluminum-containing explosive formulation.
TL;DR: In this article, an energetic polymer (HP-1) was introduced to coat RDX with 2,4,6-trinitrotoluene (TNT) by combining the solvent-nonsolvent and the aqueous suspension-melting method.
Abstract: To improve the safety of RDX (hexogen), an energetic polymer (HP-1) was introduced to coat RDX with 2,4,6-trinitrotoluene (TNT) by combining the solvent–nonsolvent and the aqueous suspension-melting method. Scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray photoelectron spectrometry (XPS) were employed to characterize the samples, and the role of HP-1 in the coating process was discussed. The impact sensitivity, friction sensitivity, and the thermal stability of unprocessed and coated RDX were investigated, and the explosion heat of samples was also estimated. Results indicate that HP-1 improves the wetting ability of the liquid coating material on RDX surface and reinforces the connection between RDX and the coating material. By surface coating, the impact and friction sensitivity of RDX decrease obviously; the drop height (H50) is increased from 37.2 to 58.4 cm, and the friction probability is reduced from 92 to 38%. The activation energy (E) and the self-ignition temperature increase by 10457.38 J⋅mol−1 and 1.8 K, respectively. The explosion heat is reduced merely by 0.93%.
TL;DR: In this paper, the authors describe the synthesis and characterization of bis-(triaminoguanidinium)-3,3′-dinitro-5,5′-azo-1,2,4-triazolate (TAGDNAT), a novel high-nitrogen molecule that derives its energy release from both a high heat of formation and intramolecular oxidation reactions.
Abstract: This paper describes the synthesis and characterization of bis-(triaminoguanidinium)-3,3′-dinitro-5,5′-azo-1,2,4-triazolate (TAGDNAT), a novel high-nitrogen molecule that derives its energy release from both a high heat of formation and intramolecular oxidation reactions. TAGDNAT shows promise as a propellant or explosive ingredient not only due to its high nitrogen content (66.35 wt.-%) but also due to its high hydrogen content (4.34 wt.-%). This new molecule has been characterized with respect to its morphology, sensitivity properties, explosive, and combustion performance. The heat of formation of TAGDNAT was also experimentally determined. The results of these studies show that TAGDNAT has one of the fastest low-pressure burning rates (at 6.9 MPa) measured till date, 6.79 cm s−1 at 6.9 MPa (39% faster than triaminoguanidinium azotetrazolate (TAGzT), a comparable high-nitrogen/high-hydrogen material). Furthermore, its pressure sensitivity is 0.507, a 33% reduction compared to TAGzT.
TL;DR: In this paper, the manufacturing of spherical ammonium dinitramide (ADN) particles with useful morphology and reproducible quality is realized by means of the emulsion crystallization process.
Abstract: Ammonium dinitramide (ADN) is the promising oxidizer, which is expected to be applied, e.g., in solid rocket propellants. The manufacturing of spherical ADN particles (the so-called ADN-Prills) with useful morphology and reproducible quality is realized by means of the emulsion crystallization process.
TL;DR: A number of fuel blends based on 3-carene, norbornadiene, furfuryl alcohol, ethylidene norbornene, and kerosene in different weight proportions have been developed as rocket fuels which exhibit synergistic hypergolic ignition with red fuming nitric acid (RFNA) as oxidizer with low ignition delays as mentioned in this paper.
Abstract: A number of fuel blends based on 3-carene, norbornadiene, furfuryl alcohol, ethylidene norbornene, and kerosene in different weight proportions have been developed as rocket fuels which exhibit synergistic hypergolic ignition with red fuming nitric acid (RFNA) as oxidizer with low ignition delays (IDs<40 ms). The optimum compositions of fuel blends were determined by measuring ID values of different blends at optimum O/F ratios. Eight selected fuel blends and one neat fuel (ethylidene norbornene) were theoretically evaluated for their performance parameters using NASA-CEC-71 software with RFNA as oxidizer at different O/F ratios and at chamber pressure of Pc, 2451.66 and 4903.33 (or 5197.52) kPa, keeping the exit pressure constant at 98.07 kPa. For experimental validation of performance parameters, static firing trials of these fuel blends with RFNA were carried out using 735.5 N thruster at 2451.66 kPa chamber pressure using doublet or triplet impinging stream type of injector. The experimental C* values were compared with theoretically determined C* values to predict combustion efficiencies which were found to be more than 95% in all the cases.
TL;DR: In this article, the void size distributions of LX-17, UFTATB, and PBXs using commercially available Cytop M, Cytop A, and Hyflon AD60 binders were derived from ultra-small-angle X-ray scattering (USAXS).
Abstract: TATB (1,3,5 triamino-2,4,6-trinitrobenzene), an extremely insensitive explosive, is used both in polymer-bound explosives (PBXs) and as an ultra-fine pressed powder (UFTATB). Many TATB-based explosives, including LX-17, a mixture of TATB and Kel-F 800 binder, experience an irreversible expansion with temperature cycling known as ratchet growth. Additional voids, with sizes hundreds of nanometers to a few micrometers, account for much of the volume expansion. Measuring these voids is important feedback for hot-spot theory and for determining the relationship between void size distributions and detonation properties. Also, understanding mechanisms for ratchet growth allows future choice of explosive/binder mixtures to minimize these types of changes, further extending PBX shelf life. This paper presents the void size distributions of LX-17, UFTATB, and PBXs using commercially available Cytop M, Cytop A, and Hyflon AD60 binders during temperature cycling between −55 and 70 °C. These void size distributions are derived from ultra-small-angle X-ray scattering (USAXS), a technique sensitive to structures from about 2 nm to about 2 μm. Structures with these sizes do not appreciably change in UFTATB. Compared to TATB/Kel-F 800, Cytop M and Cytop A show relatively small increases in void volume from 0.9 to 1.3% and 0.6 to 1.1%, respectively, while Hyflon fails to prevent irreversible volume expansion (1.2–4.6%). Computational mesoscale models combined with experimental results indicate both high glass transition temperature as well as TATB binder adhesion and wetting are important to minimize ratchet growth.
NATO1
TL;DR: The most recent progress in the field of advanced aerial infrared decoy flare technology is documented in this article, where 71 references from the public domain are given for the last review and a detailed review is given.
Abstract: The most recent progress in the field of advanced aerial infrared decoy flare technology is documented. 71 references from the public domain are given. For the last review please see Ref. [2].
TL;DR: In this paper, the authors show the good ability of electrochemical sensors to the trace detection or discrimination of explosives, including peroxide explosives, in contaminated soil and demonstrate the ability of these sensors to detect explosives.
Abstract: Few years ago, the Fraunhofer Institute for Chemical Technology started researching the detection of the explosive TNT (2,4,6-trinitrotoluene) in contaminated soil. This research resulted in a European patent and a sensor prototype. After successful transfer of the developed detection technology from the solid to the gaseous phase, nearly 20 additional explosives were researched. Most of these explosives were nitroaromatic compounds, but in the last few years some work has also been done with peroxide explosives as a response to terrorist threats. The current article shows the good ability of electrochemical sensors to the trace detection or discrimination of explosives.
TL;DR: In this article, a new approach is introduced to predict the electrostatic sensitivity of nitramines on the basis of their molecular structure, based on the ratio of carbon to oxygen and the existence of two specific structural parameters.
Abstract: In this paper, a new approach is introduced to predict the electrostatic sensitivity of nitramines on the basis of their molecular structure. The ratio of carbon to oxygen and the existence of two specific structural parameters can be used for the prediction of the electrostatic sensitivity of nitramines. The results are also compared with quantum mechanical computations from [9] so that the new method gives better predictions with respect to the measured data. Electrostatic sensitivities calculated by the new method for two new nitramines CL-20 [2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane] and TNAZ [1,3,3-trinitroazatidine] are also close to the experimental data.
TL;DR: In this paper, three nitrocellulose-based propellants for use in micro gas generators equipped with different stabilizing systems have been investigated to assess the stabilization capability with regard to in-service time, whereby strong timetemperature profiles have been applied.
Abstract: Three nitrocellulose-based propellants for use in micro gas generators equipped with different stabilizing systems have been investigated to assess the stabilization capability with regard to in-service time, whereby strong time–temperature profiles have been applied. The three stabilizing systems have been (i) 0.74 mass-% diphenylamine (DPA) and 0.48 mass-% Akardite II (Ak II); (ii) 1.25 mass-% Ak II; (iii) 2.04 mass-% Ak II. Several profiles were considered. Two simulate the heating at sun exposure in hot areas, others consider environmental temperatures in hot-humid and hot-dry areas. They were evaluated according to the load and finally one was chosen for the assessment. The contents of stabilizers were determined by high performance liquid chromatography after Soxhlet type extraction. To describe stabilizer consumption, the most suitable kinetic model was taken. Therewith a prediction was made using the chosen time–temperature profile named ‘Phoenix’, designed for temperatures at the steering wheel. The objective was to reach with this profile 15 years until the consumption of primary stabilizer content. This is conservative, because with the stabilizing action of the consecutive products of the stabilizers longer times are possible.
TL;DR: In this paper, a semi-continuous remote controlled production plant in pilot scale was set up and a modified reaction injection molding process was applied. But this process is not suitable for large-scale applications.
Abstract: Foamed propellants are based on crystalline explosives bonded in energetic reaction polymers. Due to their porous structures they are distinguished by high burning rates. Energy content and material characteristics can be varied by using different energetic fillers, energetic polymers and porous structures. Foamed charges can be produced easily by the reaction injection moulding process. For the manufacturing of foamed propellants a semi-continuous remote controlled production plant in pilot scale was set up and a modified reaction injection moulding process was applied.
TL;DR: In this paper, the effect of additive ammonium dichromate (ADC) on the burning characteristics of ammonium nitrate (AN)-based composite propellants has been investigated.
Abstract: Ammonium nitrate (AN)-based composite propellants have attracted much attention, primarily because of the clean burning nature of AN as an oxidizer However, such propellants have some disadvantages such as poor ignition and low burning rate Ammonium dichromate (ADC) is used as a burning catalyst for AN-based propellants; however, the effect of ADC on the burning characteristics has yet to be sufficiently delineated The burning characteristics of AN/ADC propellants prepared with various contents of AN and ADC have been investigated in this study The theoretical performance of an AN-based propellant is improved by the addition of ADC The increase in the burning rate is enhanced and the pressure deflagration limit (PDL) becomes lower with increasing amount of ADC added The increasing ratio of the burning rate with respect to the amount of ADC is independent of the AN content and the combustion pressure The optimal amount of ADC for improving the burning characteristics has been determined
TL;DR: The temperature-dependent solubility of hexanitrostilbene (HNS) was determined in ten solvents and solvent blends using the Tyndall effect as mentioned in this paper.
Abstract: The temperature-dependent solubility of hexanitrostilbene (HNS) [CAS# 20062-22-0] was determined in ten solvents and solvent blends using the Tyndall effect. Thermodynamic modeling of the data yielded Flory interaction parameters, the molar enthalpy of mixing, the molar entropy of mixing, and the molar Gibbs energy of mixing. All solutions exhibited endothermic enthalpies and positive entropies of mixing. The presence of water in some of the solvent blends made dissolution increasingly endothermic and disfavored solubility. The solubilities of HNS at 25 °C were used to determine the three-component Hansen solubility parameters (HSP) (δD=18.6, δP=13.5, δH=6.1 MPa1/2) and the radius of the solubility sphere (R0=5.8 MPa1/2). The HSP determined for HNS using group-additivity (δD=21.0, δP=13.3, and δH=8.6 MPa1/2) also correctly predicted the optimum solvents for this explosive.
TL;DR: In this article, the effect of incorporation of TATB on physical, thermal, and sensitivity behavior as well as initiation by small and high caliber shaped charges has been determined, and the incorporation of 10−20% TAB at the cost of RDX led to a remarkable increase in density (1.43→1.49"g"cm−3) and tensile strength (10→15"kg cm−2) compared to the control composition RDX/HTPB(85/15).
Abstract: Hydroxyl-terminated polybutadiene (HTPB) based sheet explosives incorporating insensitive 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) as a part replacement of cyclotrimethylene trinitramine (RDX) have been prepared during this work. The effect of incorporation of TATB on physical, thermal, and sensitivity behavior as well as initiation by small and high caliber shaped charges has been determined. Composition containing 85% dioctyl phthalate (DOP) coated RDX and 15% HTPB binder was taken as control. The incorporation of 10–20% TATB at the cost of RDX led to a remarkable increase in density (1.43→1.49 g cm−3) and tensile strength (10→15 kg cm−2) compared to the control composition RDX/HTPB(85/15). RDX/TATB/HTPB based compositions were found less vulnerable to shock stimuli. Shock sensitivity was found to be of the order of 20.0–29.2 GPa as against 18.0 GPa for control composition whereas their energetics in terms of velocity of detonation (VOD) were altered marginally. Differential scanning calorimeter (DSC) and thermogravimetry (TG) studies brought out that compositions undergo major decomposition in the temperature region of 170–240 °C.
TL;DR: The thermal decomposition of ammonium perchlorate has been extensively studied in the past as discussed by the authors, and various results illustrate significant differences regarding the influence of different parameters on the decomposition and a lack of useful quantitative laws to predict the thermal behavior of this crystal under a range of conditions (temperature, duration of exposure, presence of confinement).
Abstract: The thermal decomposition of ammonium perchlorate has been extensively studied in the past. Nevertheless, the various results published illustrate, on the one hand, significant differences regarding the influence of different parameters on the decomposition and on the other hand, a lack of useful quantitative laws to predict the thermal behaviour of this crystal under a range of conditions (temperature, duration of exposure, presence of confinement).
TL;DR: In this paper, the effect of crystal habit modifiers (CHM) on morphology, purity, thermal properties, and short duration shock pulses sensitivity of HNS was investigated by recrystallizing from ultra-pure water by the prefilming twin-fluid nozzle-assisted precipitation (PTFN-P) method with two different CHMs and without CHM.
Abstract: In order to investigate the effect of crystal habit modifiers (CHM) on morphology, purity, thermal properties, and short duration shock pulses sensitivity of HNS, nanocrystalline HNS was recrystallized from ultra-pure water by the prefilming twin-fluid nozzle-assisted precipitation (PTFN-P) method with two different CHMs and without CHM. Sodium carboxymethyl cellulose (CMC-Na) and white dextrine (WD) were selected as CHMs. The particles were characterized using SEM, BET, HPLC, DSC, and electrically exploded metal-foil driven flyer plate. The morphology of HNS explosive without modifiers was demonstrated to be short plate-like. However, in the presence of CMC-Na and WD as modifiers, long plate-like and ellipsoid morphologies were observed, respectively. The nanocrystalline HNS prepared with CMC-Na was more receptive to high velocity flyer impact than samples produced under the other two conditions. Its sensitivity to short duration shock waves was elevated to twice the value of HNS obtained in the absence of modifiers. CMC-Na was found to be a better modifier.
TL;DR: In this paper, mass-sensitive devices coated with substance specific molecularly imprinted polymers (MIPs) look promising to achieve low-cost detection devices capable of detecting gaseous explosives traces fast, sensitively and reliably.
Abstract: In view of the recent terror acts for example against aviation or underground transportation systems, it is obvious that the detection techniques used today for explosives are inadequate and have to be improved. In concern with national security there is need for inexpensive, rapid, highly sensitive and selective sensors. In this respect, mass-sensitive devices coated with substance specific molecularly imprinted polymers (MIPs) look promising to achieve low-cost detection devices capable of detecting gaseous explosives traces fast, sensitively and reliably. Preliminary results and possible concepts for MIP-based low-cost sensors are presented in this paper.