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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Tailoring Energy Release and Improving Processes in Additively Manufactured Reactive and Energetic Materials
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X-ray and laser based phosphor thermometry measurements and their application toward energetic materials
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X-ray and laser based phosphor thermometry measurements and their application toward energetic materials
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The Role of Pressure-Dependent Viscoplasticity and Volumetric Dilatation in Energetic Materials at Intermediate Strain Rates
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Thermal ignition of four aluminized energetic materials
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Extrusion-spheronization of energetic materials with induced porosity
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JANNAF 17th Propulsion Systems Hazards Subcommittee Meeting
Volume 1, the first of two volumes is a compilation of 16 unclassified/unlimited technical papers presented at the 17th meeting of the Joint Army-Navy-NASA-Air Force (JANNAF) Propulsion Systems Hazards Subcommittee (PSHS) held jointly with the 35th Combustion Subcommittee (CS) and Airbreathing Propulsion Subcommittee (APS). The meeting was held on 7 - 11 December 1998 at Raytheon Systems Company and the Marriott Hotel, Tucson, AZ. Topics covered include projectile and shaped charge jet impact vulnerability of munitions; thermal decomposition and cookoff behavior of energetic materials; damage and hot spot initiation mechanisms with energetic materials; detonation phenomena of solid energetic materials; and hazard classification, insensitive munitions, and propulsion systems safety.
20th JANNAF Propulsion Systems Hazards Subcommittee Meeting
This volume, the first of two volumes, is a collection of 24 unclassified/unlimited-distribution papers which were presented at the Joint Army-Navy-NASA-Air Force (JANNAF) 20th Propulsion Systems Hazards Subcommittee (PSHS), 38th Combustion Subcommittee (CS), 26th Airbreathing Propulsion Subcommittee (APS), and 21 Modeling and Simulation Subcommittee meeting. The meeting was held 8-12 April 2002 at the Bayside Inn at The Sandestin Golf & Beach Resort and Eglin Air Force Base, Destin, Florida. Topics covered include: insensitive munitions and hazard classification testing of solid rocket motors and other munitions; vulnerability of gun propellants to impact stimuli; thermal decomposition and cookoff properties of energetic materials; burn-to-violent reaction phenomena in energetic materials; and shock-to-detonation properties of solid propellants and energetic materials.
Synthesis and investigation into explosive sensitivity for a series of new picramide explosives
Tailoring the molecular properties that govern energetic material sensitivity is essential to improve safety and help develop new energetic materials. Despite this need, understanding the complex chemistry and physics of explosive initiation and propagation is still a challenge. Recent work by our group has reinforced the view that explosive sensitivity under sub-shock conditions is connected to the strength of the weakest covalent bond in the molecule, that is, its “trigger linkage.” These correlations have been observed with different classes of energetic molecules and indicate that “trigger linkage” bond breaking, and heat of explosion are good indicators for the sensitivity trends. Herein we report the synthesis of aliphatic energetic materials with ethane, propane and neopentane backbones. Experimental and computational studies show that the trigger linkage model, based on results from quantum molecular dynamics simulations, correctly predicts trends observed in the impact sensitivity of the molecules. However, while the model predicts the impact sensitivities of the ethane series, the neopentane series has higher impact sensitivities than predicted, which is presumably influenced by crystal packing effects.
Detonation Waves in High Explosives
A material at high temperature can react or decompose. For an energetic material, the reaction is exothermic and releases chemical energy that would further increase the temperature. Under some circumstances, when a reaction is triggered, such a reaction can propagate and the material rapidly releases a large amount of energy giving rise to an explosion. Examples of such materials are aerosols, suspensions of solid particles or liquid droplets in a gas; such as coal dust, grain dust and fuel-air explosions. Frequently, explosions are due to accidents. A spectacularly destructive example is the recent explosion of a large quantity of ammonium nitrate (thousands of tons) in Beirut, Lebanon (August 2020); see for example Beirut explosion. Ammonium nitrate is used as a fertilizer. It and the aerosols are not considered to be explosives due to the limited conditions for which an explosion can occur. An aerosol gets the oxidizer from the surrounding air. Burning requires diffusion of the oxidizer to the particle surface where the reaction occurs. A large density of small particles is required for a fast enough reaction to support an explosion. In contrast, an explosive is an energetic material with both fuel and oxidizer mixed on a molecular scale (either premixed gases or within molecules of a solid). This allows fast enough reactions over a wide range of conditions to support a self-propagating reactive wave known as a detonation wave. A detonation wave can be controlled and an explosive used for useful purposes such as in mining, construction, demolition, explosive welding, argon flash lamp, pulsed power using a magnetic flux generator [see also Goforth et al., 2015], jet cutter with shaped charge, explosive art, and generating conditions to study the response of materials at high strain rates and high pressures [see for example, Marsh, 1980]. Explosives are also used in conventional munitions and nuclear weapons. The focus of this book is on the theory and phenomenology of solid high explosives (HEs); in particular, plastic-bonded explosives (PBXs). Some aspects of detonation wave theory are needed to interpret explosive data. Hence, the theory is presented before the detonation wave phenomenology. A familiarity with fluid flow, specifically the notion of shock waves and the shock loci are assumed. In the remainder of this chapter we give a brief overview on the basic properties of detonation waves and PBXs.
Oxadiazole-based Heterocycles as Building Block for Material Property Control: Design, Synthesis, and Characterization of 3,4-Bis(3-(4-nitro-1,2,5-oxadiazol-3-yl)- 1,2,4-oxadiazol-5-yl)-1,2,5-oxadiazole (LLM-210)
This paper presents an approach to novel oxadiazole-based melt-castable energetic material, LLM-210. Used in pour-in process and 3D printing, melt-castable energetic materials (MCEM) must possess required physical and safety properties of industry-standard energetic materials, also a narrow range of melting point between 80-100 °C. Melting point is difficult to accurately predict, therefore, searching for MCEM is challenging. 3,4-Bis(5-(4-nitro-1,2,5-oxadiazol-3-yl)-1,2,4-oxadiazol3-yl)-1,2,5-oxadiazole (LLM-205), composed of five-oxadiazole rings allied via carbon-carbon bonds, was selected as new MCEM candidate. The target molecule was synthesized and characterized, showing a density of 1.807g/cm3 ; thermal decomposing temperature at 299 °C; and insensitive to external stimuli, but the melting point of 104 °C was out of the rang. Based on the molecular properties and ab initio calculations, 3,4-bis(3-(4-nitro-1,2,5-oxadiazol-3-yl)-1,2,4-oxadiazol-5-yl)- 1,2,5-oxadiazole (LLM-210), an isomer of LLM-205, was designed and synthesized from a different way. LLM-210 was characterized as MCEM, possessing melting point of 87 °C; density of 1.812 g/cm3 ; and exothermally decomposing temperature at 314 °C; being insensitive to external stimuli. In this study, the relationship of molecular structure to properties of LLM-205 and LLM-210 based on the results of Density Functional Theory (DFT) and X-ray crystallographic analysis is also briefly discussed.
Enhanced alkaline hydrolysis and biodegradability studies of nitrocellulose-bearing missile propellant
Large amounts of energetic materials which have been accumulated over the years in various manufacturing and military installations must be disposed of in an environmentally sound manner. Historically, the method of choice for destruction of obsolete or aging energetic materials has been open burning or open detonation (OB/OD). This destruction approach has become undesirable due to air pollution problems. Therefore, there is a need for new technologies which will effectively and economically deal with the disposal of energetic materials. Along those lines, we have investigated a chemical/biological process for the safe destruction and disposal of a double base solid rocket propellant (AHH), which was used in several 8 inch projectile systems. The solid propellant is made of nitrocellulose and nitroglycerin as energetic components, two lead salts which act as ballistic modifiers, triacetin as a plasticizer and 2-Nitrodiphenylamine (2-NDPA) as a stabilizer. A process train is being developed to convert the organic components of the propellant to biodegradable products and remove the lead from the process stream. The solid propellant is first hydrolyzed through an enhanced alkaline hydrolysis process step. Following lead removal and neutralization, the digested liquor rich in nitrates and nitrites is found to be easily biodegradable. The digestion rate of the intact ground propellant as well as the release of nitrite and nitrate groups were substantially increased when ultrasound were supplied to the alkaline reaction medium compared to the conventional alkaline hydrolysis. The effects of reaction time, temperature, sodium hydroxide concentration and other relevant parameters on the digestion efficiency and biodegradability have been studied. The present work indicates that the AHH propellant can be disposed of safely with a combination of physiochemical and biological processes.
JANNAF 18th Propulsion Systems Hazards Subcommittee Meeting
This volume, the first of two volumes is a compilation of 18 unclassified/unlimited-distribution technical papers presented at the Joint Army-Navy-NASA-Air Force (JANNAF) 18th Propulsion Systems Hazards Subcommittee (PSHS) meeting held jointly with the 36th Combustion Subcommittee (CS) and 24th Airbreathing Propulsion Subcommittee (APS) meetings. The meeting was held 18-21 October 1999 at NASA Kennedy Space Center and The DoubleTree Oceanfront Hotel, Cocoa Beach, Florida. Topics covered at the PSHS meeting include: shaped charge jet and kinetic energy penetrator impact vulnerability of gun propellants; thermal decomposition and cookoff behavior of energetic materials; violent reaction; detonation phenomena of solid energetic materials subjected to shock and impact stimuli; and hazard classification, insensitive munitions, and propulsion systems safety.
Inelastic peridynamic model for molecular crystal particles
The peridynamic theory of solid mechanics is applied to modeling the deformation and fracture of micrometer-sized particles made of organic crystalline material. A new peridynamic material model is proposed to reproduce the elastic–plastic response, creep, and fracture that are observed in experiments. The model is implemented in a three-dimensional, meshless Lagrangian simulation code. In the small deformation, elastic regime, the model agrees well with classical Hertzian contact analysis for a sphere compressed between rigid plates. Under higher load, material and geometrical nonlinearity is predicted, leading to fracture. Finally, the material parameters for the energetic material CL-20 are evaluated from nanoindentation test data on the cyclic compression and failure of micrometer-sized grains.
JANNAF 19th Propulsion Systems Hazards Subcommittee Meeting
This volume, the first of two volumes is a compilation of 25 unclassified/unlimited-distribution technical papers presented at the Joint Army-Navy-NASA-Air Force (JANNAF) 19th Propulsion Systems Hazards Subcommittee (PSHS) meeting held jointly with the 37th Combustion Subcommittee (CS) and 25th Airbreathing Propulsion Subcommittee (APS), and 1st Modeling and Simulation Subcommittee (MSS) meetings. The meeting was held 13-17 November 2000 at the Naval Postgraduate School and Hyatt Regency Hotel, Monterey, California. Topics covered at the PSHS meeting include: impact and thermal vulnerability of gun propellants; thermal decomposition and cookoff behavior of energetic materials; violent reaction and detonation phenomena of solid energetic materials subjected to shock and impact loading; and hazard classification, and insensitive munitions testing of propellants and propulsion systems.
Mode-Selective Vibrational Energy Transfer Dynamics in 1,3,5-Trinitroperhydro-1,3,5-triazine (RDX) Thin Films
The coupling of inter- and intramolecular vibrations plays a critical role in initiating chemistry during the shock-to-detonation transition in energetic materials. In this work, we report on the subpicosecond to subnanosecond vibrational energy transfer (VET) dynamics of the solid energetic material 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) by using broadband, ultrafast infrared transient absorption spectroscopy. Experiments reveal VET occurring on three distinct time scales: subpicosecond, 5 ps, and 200 ps. The ultrafast appearance of signal at all probed modes in the mid-infrared suggests strong anharmonic coupling of all vibrations in the solid, whereas the long-lived evolution demonstrates that VET is incomplete, and thus thermal equilibrium is not attained, even on the 100 ps time scale. Density functional theory and classical molecular dynamics simulations provide valuable insights into the experimental observations, revealing compression-insensitive time scales for the initial VET dynamics of high-frequency vibrations and drastically extended relaxation times for low-frequency phonon modes under lattice compression. Mode selectivity of the longest dynamics suggests coupling of the N–N and axial NO2 stretching modes with the long-lived, excited phonon bath.
Explosive materials equivalency, test methods and evaluation
Attention is given to concepts of explosive equivalency of energetic materials based on specific airblast parameters. A description is provided of a wide bandwidth high accuracy instrumentation system which has been used extensively in obtaining pressure time profiles of energetic materials. The object of the considered test method is to determine the maximum output from the detonation of explosive materials in terms of airblast overpressure and positive impulse. The measured pressure and impulse values are compared with known characteristics of hemispherical TNT data to determine the equivalency of the test material in relation to TNT. An investigation shows that meaningful comparisons between various explosives and a standard reference material such as TNT should be based upon the same parameters. The tests should be conducted under the same conditions.