Showing papers on "Ammonium perchlorate published in 2002"

Perchlorate as an environmental contaminant.

Abstract: Perchlorate anion (ClO4-) has been found in drinking water supplies throughout the southwestern United States. It is primarily associated with releases of ammonium perchlorate by defense contractors, military operations, and aerospace programs. Ammonium perchlorate is used as a solid oxidant in missile and rocket propulsion systems. Traces of perchlorate are found in Chile saltpeter, but the use of such fertilizer has not been associated with large scale contamination. Although it is a strong oxidant, perchlorate anion is very persistent in the environment due to the high activation energy associated with its reduction. At high enough concentrations, perchlorate can affect thyroid gland functions, where it is mistakenly taken up in place of iodide. A safe daily exposure has not yet been set, but is expected to be released in 2002. Perchlorate is measured in environmental samples primarily by ion chromatography. It can be removed by anion exchange or membrane filtration. It is destroyed by some biological and chemical processes. The environmental occurrence, toxicity, analytical chemistry, and remediative approaches are discussed.

Environmentally relevant concentrations of ammonium perchlorate inhibit development and metamorphosis in Xenopus laevis.

Abstract: We determined whether environmentally relevant concentrations of ammonium perchlorate alter development and metamorphosis in Xenopus laevis. Eggs and larvae were exposed to varying concentrations of ammonium perchlorate or control medium for 70 d. Most treatment-related mortality was observed within 5 d after exposure and was due in large part to reduced hatching success. The 5- and 70-d median lethal concentrations (LC50s) were 510 +/- 36 mg ammonium perchlorate/L and 223 +/- 13 mg ammonium perchlorate/L, respectively. Ammonium perchlorate did not cause any concentration-related developmental abnormalities at concentrations below the 70-d LC50. Ammonium perchlorate inhibited metamorphosis in a concentration-dependent manner as evident from effects on forelimb emergence, tail resorption, and hindlimb growth. These effects were observed after exposure to ammonium perchlorate concentrations in the parts-per-billion range, at or below concentrations reported in surface waters contaminated with ammonium perchlorate. Ammonium perchlorate significantly inhibited tail resorption after a 14-d exposure in the U.S. Environmental Protection Agency (U.S. EPA) Endocrine Disruptor Screening and Testing Committee (EDSTAC) Tier I frog metamorphosis assay for thyroid disruption in amphibians. We believe that ammonium perchlorate may pose a threat to normal development and growth in natural amphibian populations.

Reactive projectiles for exploding unexploded ordnance

Abstract: A projectile for the destruction of unexploded ordnance comprising a dart shell having a core region which contains a reactive composition comprised of a reactive metal and an oxidizer. The reactive metal is selected from the group consisting of titanium, aluminum, magnesium, lithium, beryllium, zirconium, thorium, uranium, hafnium, alloys thereof, hydrides thereof, and combinations thereof. The oxidizer is selected from the group consisting of lithium perchlorate, magnesium perchlorate, ammonium perchlorate, potassium perchlorate, chlorates, peroxides, and combinations thereof. In an alternative embodiment, the reactive composition is located on the outside of a center penetrating rod. Also included is a disposable apparatus for delivering a projectile to destroy unexploded ordnance. The apparatus is comprised of a block having a top and a bottom, the block comprised of a material selected from the group consisting of wood and polymeric resin. Within the block is a barrel disposed on the bottom of the block, the barrel comprised of a material selected from the group consisting of fiberglass and polymeric resin.

Combustion response of ammonium perchlorate composite propellants

Abstract: The Cohen and Strand model for ammonium perchlorate (AP) composite propellants is applied as boundary conditions, one for AP and one for binder, in solving the heat conduction equation in each to compute linear and nonlinear combustion response properties for each and for the aggregate propellant. Iterations couple AP and binder through the quasi-steady flame processes. Illustrative results for linear response functions (pressure coupled and velocity coupled) are presented for a monomodal AP propellant showing effects of varying AP size, pressure, and crossflow speed. Examples of nonlinear responses to arbitrary waveforms are also shown. The model predicts a very large response at high pressures with coarse AP due to AP monopropellant combustion, underpredicts peak response amplitude for low pressures due to a possible change in mechanism, and shows a stabilizing effect of the diffusion flame. A quantitative comparison with response function data is limited to one well-characterized research formulation. Mechanistic implications are discussed, including recommendations for future modeling work.

Three-dimensional heterogeneous propellant combustion

Abstract: A numerical framework is described which permits the calculation of the three-dimensional combustion field supported by a heterogeneous propellant, allowing for complete coupling between the condensed-phase physics, the gas-phase physics, and the unsteady uneven, regressing surface. A random-packing algorithm is used to construct models of ammonium perchlorate (AP) in hydroxyl-terminated polybutadiene propellants which minic experimental propellants designed by R. Miller, and these are numerically burnt, Mean burning rates are compared with experimental data for four packs, over a pressure range of 7–200 atm. The effect of the local propellant morphology on the local surface regression speed is examined, with particular attention to the behavior in the neighborhood of large AP particles, At first, these burn slowly and protrude significantly above the surrounding surface, but later they are rapidly consumed and the surface flattens. In all cases, mean burning rates can be accurately calculated using an Oseen approximation for the velocity field, rather than solving the Navier-Stokes equations.

Modeling the combustion of propellant sandwiches

Abstract: A two-dimensional, steady-state model of a burning composite solid propellant is developed to study the characteristics of the combustion process. The solid composite is a periodic sandwich unit comprised of two oxidizer laminates (ammonium perchlorate, AP) separated by a fuel binder layer (hydroxyl-terminated polybutadiene, HTPB). Included in the model are essential features for simulating composite propellant combustion: (1) a free surface boundary, (2) gas- and condensed-phase heat release distributions based on simplified chemical kinetics, and (3) an implicit surface regression rate (unique burning rate) determined by coupled gas-solid energy/species transport analysis. Comparisons of the model with experimental observations focus on surface geometry, flame structure, and the burning rate for variations in pressure, particle size, binder width, and propellant formulation. Experimentally observed trends for typical composite propellants are replicated. For example, the relative protrusion/recession of...

Combustion of Solid Propellants

Abstract: : A review of the understanding of the combustion mechanisms of solid propellants that the authors have built from their work and from the literature is presented. Such an understanding is an important part of the process carried out to master the behavior of solid propellants and to obtain desired characteristics (with respect to energetic level, burning rate level, sensitivity to pressure and initial temperature, nature of emitted combustion products, vulnerability to various aggressions...). The propellants and propellant components considered are: double-base propellants, based on nitrocellulose and nitroglycerin, " active binder, based on an inert polymer (or energetic such as PAG) and a liquid nitrate ester, inert binders, such as polybutadiene, ammonium perchlorate, nitramines, such as HMX, RDX and CL20 (HNIW), composite ammonium perchlorate-inert binder propellants, composite propellants based on a nitramine and an active binder, aluminum, with respect to the two previous types of propellants, additives, when appropriate. The features of the combustion zone described are: In the condensed phase, the thickness of the temperature profile and of the decomposition zone, the kinetics of the decomposition, the energy released, the nature of the gases evolved, the surface temperature; In the gas phase, the type of flame structure (diffusion or kinetically controlled), the possibility of staging (such as in double-base propellants), the kinetics of the reaction(s), the energy released, the flame temperature (primary and final, when applicable).

Redox-active films formed by electrochemical reduction of solutions of C60 and platinum complexes

Abstract: Electroreduction of a toluene–acetonitrile (4∶1 v/v) solution of C60 and cis-Pt(py)2Cl2 in the presence of 0.10 M tetra(n-butyl)ammonium perchlorate as supporting electrolyte produces a black, redox active film that coats the electrode surface. This film retains its redox activity when transferred to an acetonitrile solution that contains only the supporting electrolyte, 0.10 M tetra(n-butyl)ammonium perchlorate. The film has been characterized by infrared spectroscopy, laser desorption mass spectrometry, and XPS spectroscopy. The formation of this film is dependent on the platinum complex used as precursor and on the potential range utilized during film growth. No film growth is observed when Pt(bipy)Cl2, Pt(py)2I2, cis-Pt(PPh3)2Cl2 or trans-Pt(py)2Cl2 are used as precursors, but {Pt(μ-Cl)Cl(C2H4)}2 is a useful precursor which allows film growth at less negative potentials. Chemically prepared C60Pt1 is also electrochemically active when precipitated on a platinum electrode. The formation of an electroactive film from the electroreduction of C70 and cis-Pt(py)2Cl2 is also reported.

Gas generating composition and gas generator

Abstract: Disclosed is a gas generating composition being stable and having a heating starting temperature of 170 to 220° C, which is of a low-temperature ignition type The gas generating composition comprises ammonium perchlorate, a chlorine scavenger, and microcrystalline carbon powder The chlorine scavenger is sodium nitrate or aluminum/magnesium mixed powder, and the microcrystalline carbon powder is activated carbon or charcoal The gas generating composition preferably comprises 40 to 58% by weight of ammonium perchlorate, 30 to 41% by weight of the chlorine scavenger, and 1 to 30% by weight of the microcrystalline carbon powder

Mathematical modeling of rheological properties of hydroxyl‐terminated polybutadiene binder and dioctyl adipate plasticizer

Abstract: Solid composite propellants contain 80–90% of a crystalline oxidizer like ammonium perchlorate and powdery metallic fuel like aluminum with 10 to 15% organic binders like HTPB or CTPB, to bind the solids together and maintain the shape under severe stress and strain environment. Also, the propellant must not crack or become brittle at subzero temperatures. Formulating and processing of the highly filled composite propellants are difficult tasks and need a thorough understanding of rheology, even apart from a knowledge of propellant chemistry, particulate technology, manufacturing methods, and safe handling of explosives and hazardous materials. The flow behavior or rheology of the propellant slurry determines the ingredients and some of the abnormalities of the motor during firing. The propellant viscosity and mechanical properties are determined by the binder system, and the unloading viscosity of the propellant slurry is dependent on the initial viscosity of the binder system, solid loading, particle size, and its distribution, shape, temperature, and pressure. In the present report an attempt is made to study the dependency of viscosity of the HTPB binder system on temperature, plasticizer level (composition), and torque (angular velocity of spindle). The viscosity measurements were made using a Brookfield viscometer model DV III at different plasticizer levels (10–50%), temperatures (30–65°C), and torques (50–100%). The data indicate that the viscosity of HTPB, DOA, and their mixture decreases with increasing temperature and is constant with torque. The Arrhenius equation gives the energy for viscous flow to be ≅35 kcal/mol for HTPB. The variation of viscosity with temperature of HTPB/DOA and their mixture follows a mathematical model expressed as where T is the temperature and a1, a2, a3, a4, and a5 are the constants. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1002–1007, 2002

Reactive projectiles, delivery devices therefor, and methods for their use in the destruction of unexploded ordnance

Abstract: A projectile for the destruction of unexploded ordnance comprising a projectile shell having a core region which contains a reactive composition comprised of a reactive metal and an oxidizer. The reactive metal is selected from the group consisting of titanium, aluminum, magnesium, lithium, beryllium, zirconium, thorium, uranium, hafnium, alloys thereof, hydrides thereof, and combinations thereof. The oxidizer is selected from the group consisting of lithium perchlorate, lithium chlorate, magnesium perchlorate, magnesium chlorate, ammonium perchlorate, ammonium chlorate, potassium perchlorate, potassium chlorate, oxides thereof, peroxides thereof, and combinations thereof. Also included are methods of destroying unexploded ordnance and disposable apparati for delivering a projectile to destroy unexploded ordnance.

Role of the Structure of Heterogeneous Condensed Mixtures in the Formation of Agglomerates

Abstract: Mathematical simulation of the structure of metallized heterogeneous condensed mixtures is performed. Evolution of a system of aluminum particles is studied in the case a heat wave passes over the mixture. It is shown that rapid heating of a heterogeneous condensed mixture forms a system of “clusters” of contacting aluminum particles, which may sinter to form a porous system that melts and disperses into individual droplets with further heating under the action of surface-tension forces. After coalescence, these droplets form agglomerates. The structure of “clusters” of contacting particles is studied, and the mean-mass size of metal particles is determined as a function of dispersion of the components and their concentration in the heterogeneous condensed mixture. It is shown that contacting aluminum particles in the heterogeneous condensed mixture form fractal-like structures, which may play a significant role in the course of combustion of the mixture. Key words: agglomeration of aluminum, combustion of composite rocket propellants, propellant structure, ammonium perchlorate, binder.

Fine‐tuning the mechanical properties of hydroxyl‐terminated polybutadiene/ammonium perchlorate‐based composite solid propellants by varying the NCO/OH and triol/diol ratios

Abstract: Changes in the mechanical properties of hydroxyl-terminated polybutadiene/ammonium perchlorate-based composite solid propellants were studied during the curing period with respect to variations in the crosslink density, which was predominantly determined by the equivalent ratio of diisocyanate to total hydroxyl (NCO/OH ratio) and the equivalent ratio of triol to diol (triol/diol ratio). For this purpose, 16 propellants were prepared in different compositions through changes in the NCO/OH ratios (0.81, 0.82, 0.83, and 0.85) for each triol/diol ratio (0.07, 0.09, 0.11, and 0.13) and were tested for their mechanical properties immediately after curing. The propellants with an NCO/OH ratio of 0.82 had minimum stress, modulus, and hardness with maximum strain capability, whereas the propellants with an NCO/OH ratio of 0.85 showed just the opposite behavior. Variations in the isocyanate level seemed to have more effect on the mechanical properties at higher triol/diol ratios. It was also concluded that the propellants with triol/diol–NCO/OH combinations of 0.11–0.83, 0.11–0.85, 0.13–0.81, 0.13–0.83, and 0.13–0.85 were not acceptable for upper stage case-bonded rocket applications because of either high tensile strength or high modulus. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2072–2079, 2002; DOI 10.1002/app.10605

Thermomechanical model and temperature measurements for shocked ammonium perchlorate single crystals

Abstract: A consistent thermomechanical material model was developed for unreacted ammonium perchlorate (AP) single crystals for shock compression normal to the (210) and (001) crystal planes. Building on previous work, the mechanical response for both orientations was described using a single isotropic elastic-plastic model and an overstress model to describe rate-dependent yielding. Velocity interferometer measurements to 12 GPa were performed to extend the AP Hugoniot curve to higher stresses. The specific heat cv, the coefficient of thermal pressure (∂P/∂T)V, and the isothermal bulk modulus BT were determined from Hugoniot and isothermal compression curves, along with available data at atmospheric pressure. Time-resolved Raman spectroscopy experiments were carried out under stepwise loading to obtain temperatures in the shocked state. Calculated temperatures using our material model are in good agreement with the temperatures obtained from our experiments, thus providing validation for our modeling approach.

Condensed Combustion Products of Aluminized Propellants. III. Effect of an Inert Gaseous Combustion Environment

Abstract: The effect of gaseous combustion environment on particle size distribution and chemical compositions of condensed combustion products of a model propellant containing ammonium perchlorate, binder, and 23.4% aluminum was studied. Experiments were conducted at pressures of 0.6, 4.0, and 7.5MPa. Oxide particles with sizes of 1.2–60 μm and agglomerates with sizes from 60 μm to maximum were investigated. In experiments with nitrogen and helium, the difference in the mean sizes of the sampled agglomerates does not exceed the experimental error. The difference in the amount of unreacted (metallic) aluminum in the agglomerates sampled in nitrogen and helium is also negligible. Replacement of nitrogen by helium affects the size distribution of the oxide particles by increasing the mass fraction of particles with sizes of 1.2–10 μm, and this effect is enhanced with pressure.

Ammonium perchlorate/(H2+CO) gaseous fuel diffusionflame studies

Abstract: Counterflow diffusion flame experiments and modeling results are presented for a fuel mixture consisting of CO and H 2 flowing against decomposition products from a solid ammonium perchlorate (AP) pellet. The flame zone simulates the diffusion flame structure that is expected to exist between reaction products from fine AP crystals and a hydrocarbon binder with the decomposition products from large AP crystals, characteristic of a bimodal AP propellant. Quantitative species and temperature profiles have been measured for a mixture of two fuels, hydrogen and CO, and one strain rate, given by a separation of 5 mm, between the fuel exit and AP surface. Species measured included CN, NH, NO, OH, N 2 , O 2 CO 2 , H 2 , CO, HCl, and H 2 O. Temperature was measured using a combination of a thermocouple at the exit, spontaneous Raman scattering measurements throughout the flame, OH rotational population distributions, and NO vibrational population distributions. The burning rate of the AP was also measured for this flame's strain rate. The measured 12 scalars are compared with predictions from a detailed gas-phase kinetics models consisting of 86 species and 531 reactions. Model predictions are found to be in good agreement with experiment and illustrate the type of kinetic features that may be expected to occur in propellants when AP particle size distributions are varied.

Studies on effect of incorporation of BDNPF/A on burning rates of RDX/AP/AI filled CMDB propellants

Abstract: This paper reports the effect of replacement of non -energetic plasticizer diethyl phthalate (DEP) by nitroplasticizer [1:1 mixture of bis (2,2 dinitro propyl) formal (BDNPF) and bis (2,2 dinitro propyl) acetal (BDNPA)] on burning rates and Isp of nitramine (RDX) / ammonium perchlorate (AP) based composite modified double base (CMDB) propellants. Addition of BDNPF/A led to overall 9–46% increase in burning rates, as well as gain in Isp to the order of 5–10 s in both the systems. Inclusion of copper chromite (C.C.) led to further improvement in burning rates. A typical aluminized (17.5%)- ecofriendly RDX (12.5%)-CMDB formulation gave burning rates of the order of 8–22 mm/s in the pressure range of 2.9–10.8 MPa with Isp (theoretical) of 264 s. Aluminized AP-CMDB propellant with low pressure combustion limit of 1.9 MPa and burning rates of 15–31 mm/s was also realized during this work. Superior oxygen balance and heat of formation of BDNPF/A compared to DEP appear to play contributory role in this r...

Studies on energetic compounds part 15 : Transition metal salts of NTO as potential energetic ballistic modifiers for composite solid propellants

Abstract: The combustion of hydroxyl terminated polybutadiene (HTPB) - ammonium perchlorate (AP) composite solid propellants has been studied using transition metal (Mn, Fe, Co, Ni, Cu and Zn) salts of 5-nitro-2,4-dihydro-3H-1,2,4-triazole-3-one (NTO) as energetic burning rate additives. The steady burning rate (r) was considerably enhanced with Cu(NTO)2 and Fe(NTO)2 whereas moderately enhanced with Zn(NTO)2 and Co(NTO)2 at low concentration (2% by wt.). Activity of these salts has been observed during isothermal decomposition of AP at 260°C. The values of ignition delay (tiJ), ignition temperature (Tign.) and activation energy for ignition (E∗) for AP has also been lowered when these salts are added to it at 2% wt. concentration. The processing parameters as well as mechanical properties of the propellants with Cu(NTO)2 as additive have been studied in detail. The r of the propellants (both highly aluminized and less aluminized) with Cu(NTO)2 as additive at various concentrations, has been determined at h...

Gas generating agent composition

Abstract: PROBLEM TO BE SOLVED: To obtain a gas generating agent composition which consists essentially of ammonium nitrate, is excellent in rate of gasification at the time of burning and has appropriate combustion speed, with which basic combustion residue is neutralized and generation of carbon monoxide is suppressed. SOLUTION: The gas generating agent composition is characterized in that (a) component, (b) component, (c) component and (d) component described below are contained therein and value of (a)/ (a)+(b)+(c)}×100 is between 50 and 97 wt.%. (a) ammonium nitrate, (b) an oxygen acid metal salt which generates basic substances at the time of combustion, (c) ammonium perchlorate, (d) at least one kind of fuel component selected from the group consisting of a polymer binder, a high energy material and powdery fine crystalline carbon.

Biological Effects of Inadvertent Perchlorate Releases During Launch Operations

Abstract: : Solid rocket motor fuel contains large quantities of ammonium perchlorate as the primary oxidant and this material has been shown to be toxic to life. In the event of an aborted rocket launch, it is possible that unspent propellant could be deposited near the launch site and coastal marine and terrestrial habitats could be adversely affected. This report presents the results of the following experiments: effects of perchlorate on primary and secondary production in freshwater and marine water samples; decomposition processes in marine and freshwater sediments, freshwater wetland peat, and upland soils; effects of perchlorate on the behavior and growth of the fish species threespine stickleback; and the bioaccumulation of perchlorate by freshwater and marine plankton and in the threespine stickleback fish. Results show that perchlorate will affect photosynthesis in aquatic systems, but this effect appears to occur only when perchlorate levels are extremely high (1000 ppm). Bacterial production also was not adversely affected by the presence of perchlorate except at very high levels in seawater samples. Respiration in marine and freshwater sediments and wetland peat was not adversely affected by perchlorate concentrations as high as 1000 ppm. Soil samples exhibited significant decreases in respiration activity in the presence of 100 and lOOO-ppm perchlorate, so it is possible that the deposition of perchlorate to coastal soils following a flight abortion could decrease the rate that material is decomposed in soil, which could adversely affect plant growth. The presence of potassium perchlorate at concentrations up to 10 ppm and perchlorate concentrations nearing 30 ppm in aquaria containing solid propellant had no effect on stickleback mating or the birth and growth of fry. Both the algal/bacterial and fish in aquaria accumulated significant levels of perchlorate that could be passed on to other tropic levels and later lead to deleterious effects.

Modeling combustion of laminate propellants with fine ammonium perchlorate

Abstract: The combustion of AP/HTPB laminate propellants is investigated theoretically. Numerical computations are based on finite-rate chemistry with simplified kinetics and a free surface. Both pure and oxygenated binders (loaded with fine AP) are considered. The model shows the ability to qualitatively predict relative protrusion and recession of AP and binder as well as diffusion flame shape. The results show that fine-AP loading has a pronounced effect on the surface and flame structure. The addition of fine AP shows the predominance of a premixed flame over the diffusion flame, which persists over a range of laminate thickness from 100 to 600 (jm. The surface profile is also modified toward a recession of the binder with respect to AP as the width increases. The binder surface remains relatively flat (unlike the case of pure binder, which protrudes noticeably), and burns ahead of the AP, which lags behind at the pressures simulated (10 to 30 atm).

Volumetric fire-extinguishing apparatus

Abstract: fire-fighting equipment. SUBSTANCE: apparatus is made in the form of thermochemical paraaerosol generator, which may be used for volumetric extinguishing in closed and partially enclosed spaces, as well as for localizing burning processes on open areas. Apparatus has combustion chamber with solid and /or liquid, and/or gaseous fuel and igniter, fire extinguishing liquid supply source, reaction chamber arranged behind combustion chamber in housing, mixing chamber with sprayer collector connected to fire-extinguishing liquid supply source, fire-extinguishing liquid overheating chamber and set of nozzles. Apparatus is further equipped with fire-extinguishant generator or gaseous combustion retardant generator positioned in overheating chamber, which is connected at its one side with mixing chamber through baffle-type separator and at its other side with aerosol nozzle unit through receiver. Gaseous combustion retardant is of thermochemical composition. Solid fuel is formed as compressed air foam mixture of powdered magnesium and/or aluminum, and/or alloy of mentioned substances with oxygen-, or fluorine- and/or chlorine-containing oxidizer and specific additive, for example binder and/or combustion catalyst, with metal:oxidizer:specific additive ratio being 10- 40:10-30:1-5, correspondingly. Thermochemical composition is mechanical mixture and/or alloy of ammonium nitrate and ammonium phosphate, and/or ammonium perchlorate, and/or ammonium phosphate, and/or carbonate of amide (carbamide) or compound based on red phosphor, thermal mixture and combustible. EFFECT: increased fire- fighting capacity by reduced consumption of fire-extinguishing substance and improved combustion retarding properties of fire-extinguishant. 3 cl, 2 dwg

The Catalyzed Decomposition of Ammonium Perchlorate

Abstract: The influences of multiple catalysts and an energetic catalyst on thermal decomposition of ammonirm perchlorate (AP) at various pressures were investigated by pressure differential thermal analysis (PDTA). The influence of three catalysts used to this study on the high temperature decomposition is independent of the grain size of AP. On the basis of the kinetic parameters of decomposition, it was interpreted that there is the different catalytic mechanism in the decomposition of AP at various pressures. The pressure exponents of burn of the propellants can be related to the rates of the catalyzed decomposition of AP at various pressures.

Oscillations in Propellant Flames with Edges

Abstract: We examine the combustion of periodic sandwich propellants, alternating slices of ammonium perchlorate (AP) and binder. A fully-coupled combustion code, 2-D, unsteady, is used to examine the behavior for highly fuel-lean configurations for which the binder slice is thin, and the diffusion flame supported by binder gases and AP decomposition flame products generates but a small fraction of the gas-phase heat output. Under these circumstances, unexpected unsteady behavior—perhaps an instability—is uncovered and is described in detail for a pressure of 20 atm. It appears to arise partly because the AP decomposition flame has an edge and is quite distinct from the well-known instability that can arise in a 1-D flame (sans edge) supported by a homogeneous propellant.

Bis(2-pyridylmethyl)ammonium perchlorate

Abstract: # 2002 International Union of Crystallography Printed in Great Britain ± all rights reserved The title compound, C12H14N3 + ClO4, crystallizes from a solution of bis(2-pyridylmethyl)amine and HClO4 in water/ DMF (3:1, v/v) with the secondary amine N atom protonated. The two pyridine arms of the ligand are held in a closed conformation through a strong bifurcated hydrogen bond from one of the ammonium H atoms. The ClO4 ÿ anion is also hydrogen bonded to the same H atom of the ammonium N atom, with an N O distance of 2.899 (4) AÊ . The other ammonium H atom is hydrogen bonded to an O atom of a symmetry-related perchlorate anion.