Thermal Decomposition of Energetic Materials by STMBMS Measurements PDF Download

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 8

View

Book Description
Simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) and time-of-flight velocity (TOF) spectra have been developed to study reactions that occur during the thermal decomposition of liquids and solids. The data obtained with these techniques are the identity of the reaction products and their rates of gas formation as a function of time. Over the past several years, these techniques have been applied to the study of energetic materials that are used in propellants and explosives. In this presentation, the details of the STMBMS and TOF velocity spectra techniques will be reviewed, the advantages of the techniques over more conventional thermal analysis and mass spectrometry measurements will be discussed, and the use of the techniques will be illustrated with results on the thermal decomposition of hexahydro-1,3,5-trinitro-s-triazine (RDX).

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

View

Book Description

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

View

Book Description
The physical and chemical processes that control the thermal decomposition of several different types of energetic materials have been determined from measurements with a simultaneous thermogravimetric modulated beam mass spectrometer (STMBMS). The compounds studied include HMX, hexahydro-1-nitroso-3,5-dinitro-s-triazine (ONDNTA), 2,4-dinitroimidazole (24DNI), TNAZ, 1-nitro-3,3-dinitroazetidine (NDNAZ), 3-amino-5-nitro-1,2,4-triazole (ANTA), 5,5'-dinitro-3,3'-bi-1,2,4-triazole (DNBT), and a complex of DNBT.2ANTA. The results on HMX provide new insights on the solid-phase decomposition processes that take place within individual particles. The results on ONDNTA provide new insight to the reaction mechanisms that control the decomposition of this important cyclic nitramine reaction intermediate. The results on 24DNI, TNAZ, and NDNAZ provide sufficient data to construct a model of the underlying chemical and physical processes. A model has been formulated to represent the decomposition of 24DNI and the parameters for the model have been determined from the STMBMS results. The model consists of seven different physical processes, which include the nucleation and growth of a polymeric residue that acts as an "autocatalyst". Global chemical reactions are used in each step. A qualitative model of the thermal decomposition of TNAZ and NDNAZ is presented. Sufficient data has been collected to formulate mathematical models of their decomposition

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 23

View

Book Description
Through the use of simultaneous thermogravimetry modulated beam mass spectrometry (STMBMS) measurements, time-of-flight (TOF) velocity-spectra analysis, and 2H, 13C, 15N, and 18O labeled analogues of 1,3,5- trinitrohexahydro-s-triazine (RDX), the thermal decomposition products of RDX have been identified as H2O, HCN, CO, CH2O, NO, N2O, NH2CHO, NO2, HONO, (CH3) NHCHO, oxy-s-triazine (OST), and 1nitroso-3,5-dinitrohexahydro-s-triazine (ONDNTA) and all of their gas formation rates have been measured as a function of time. From these results the primary reaction pathways that control the decomposition of RDX in both the solid and liquid phases have been discovered. Four primary reaction pathways control the decomposition of RDX in the liquid phase between 200 and 215 deg C. Two pathways are first-order reactions solely in RDX. One produces predominantly OST, NO, and H2O and accounts for approximately 30% of the decomposed RDX, and the other produces predominantly N2O and CH2O with smaller amounts of NO2, CO, and NH2CHO and accounts for 10% of the decomposed RDX. The third pathway consists of formation of ONDNTA by reaction between NO and RDX, followed by the decomposition of ONDNTA to predominantly CH2O and N2o. The fourth reaction pathway consists of decomposition of RDX through reaction with a catalyst that is formed from the decomposition products of previously decomposed RDX. ONDNTA is the only product that appears to be formed during the early stages of decomposition of RDX in the solid phase.

Author: S.N. Bulusu
Publisher: Springer Science & Business Media
ISBN: 9400920350
Category : Science
Languages : en
Pages : 756

View

Book Description
This book represents a collection of lectures presented at the NATO Advanced study Institute(ASI) on "Chemistry & Physics of the Molecular Processes in Energetic Materials", held at Hotel Torre Normanna, Altavilla Milicia, Sicily, Italy, September 3 to 15, 1989. The institute was attended by seventy participants including twenty lecturers, drawn from thirteen countries. The purpose of the institute was to review the major ad vances made in recent years in the theoretical and experi mental aspects of explosives and propellants. In accordance with the format of the NATO ASI, it was arranged to have a relatively small number of speakers to present in depth, re view type lectures emphasizing the basic research aspects of the subject, over a two week period. Most of the speakers gave two lectures, each in excess of one hour with addition al time for discussions. The scope of the meeting was limit ed to molecular and spectroscopic studies since the hydro dynamic aspects of detonation and various performance crite ria of energetic materials are often covered adequately in other international meetings. An attempt was made to have a coherent presentation of various theoretical, computational and spectroscopic approaches to help a better understanding of energetic materials from a molecular point of view. The progress already made in these areas is such that structure property (e. g.

Author: Kenneth K. Kuo
Publisher: Begell House Publishers
ISBN:
Category : Combustion
Languages : en
Pages : 1114

View

Book Description
This edited book contains state-of-the-art information associated with energetic material combustion. There are twelve topical areas, including: Reaction Kinetics of Energetic Materials (Solid, Liquid, and Gel Propellants); Recycling of Energetic Materials; Combustion Performance of Hybrid and Solid Rocket Motors; Ignition and Combustion of Energetic Materials; Energetic Material Defects and Rocket Engine Flowfields; Metal Combustion; Pyrolysis and Combustion Processes of New Ingredients and Applications; Theoretical Modeling and Numerical Simulation of Combustion Processes of Energetic Materials; Combustion Diagnostic Techniques; Propellant and Rocket Motor Stability; Commercial Applications of Energetic Materials (Airbags, Gas Generators, etc.); and Thermal Insulation and Ablation Processes.

Author: Donald H. Liebenberg
Publisher:
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 416

View

Book Description
The MRS Symposium Proceeding series is an internationally recognised reference suitable for researchers and practitioners.

Author: Weiqiang Pang
Publisher: John Wiley & Sons
ISBN: 3527835334
Category : Science
Languages : en
Pages : 1005

View

Book Description
Provides an up-to-date account of innovative energetic materials and their potential applications in space propulsion and high explosives Most explosives and propellants currently use a small number of ingredients, such as TNT and nitrocellulose. In comparison to conventional materials, nano- and micro-scale energetic materials exhibit superior burning characteristics and much higher energy densities and explosive yields. Nano and Micro-scale Energetic Materials: Propellants and Explosives provides a timely overview of innovative nano-scale energetic materials (nEMs) and microscale energetic materials (μEMs) technology. Covering nEMs and μEMs ingredients as well as formulations, this comprehensive volume examines the preparation, characterization, ignition, combustion, and performance of energetic materials in various applications of propellants and explosives. Twenty-two chapters explore metal-based pyrotechnic nanocomposites, solid and hybrid rocket propulsion, solid fuels for in-space and power, the sensitivity and mechanical properties of explosives, new energetic materials, and more. Explores novel energetic materials and their potential for use in propellants and explosives Summarizes the most recent advances of leading research groups currently active in twelve countries Discusses how new environmentally friendly, high-combustion energetic materials can best be used in different applications Explains the fundamentals of energetic materials, including similarities and differences between composite propellants and explosives Nano and Micro-scale Energetic Materials: Propellants and Explosives is an important resource for materials scientists, explosives specialists, pyrotechnicians, environmental chemists, polymer chemists, physical chemists, aerospace physicians, and aerospace engineers working in both academia and industry.

Author: Donald L Thompson
Publisher: World Scientific
ISBN: 9814480908
Category : Science
Languages : en
Pages : 531

View

Book Description
Few books cover experimental and theoretical methods to characterize decomposition, combustion and detonation of energetic materials. This volume, by internationally known and major contributors to the field, is unique because it summarizes the most important recent work, what we know with confidence, and what main areas remain to be investigated. Most chapters comprise summaries of work spanning decades and contain expert commentary available nowhere else. Although energetic materials are its focus, this book provides a guide to modern methods for investigations of condensed and gas-phase reactions. Although these energetic reactions are complex and difficult to study, the work discussed here provides readers with a substantial understanding of the behavior of materials now in use, and a predictive capability for the development of new materials based on target properties.

Author: Hubert Biteau
Publisher:
ISBN:
Category :
Languages : en
Pages :

View

Book Description
Energetic materials encompass a wide range of chemical compounds all associated with a significant risk of fire and explosion. They include explosives, fireworks, pyrotechnics, powders, propellants and other unsteady chemicals. These materials store a high level of chemical energy and are able to release it rapidly without external contribution of oxygen or any other oxidizer. The behaviour of these materials in case of explosive detonations is relatively wellknown from empirical and practical points of view. However, fundamental scientific questions remain unanswered related to the mechanisms of heat release. The current understanding of these mechanisms lacks appropriate thermochemical characterisation. The aim of the study is the analysis of thermal and chemical characteristics of energetic materials under conditions that exclude detonations. Detonation is excluded in order to better isolate the thermal and chemical mechanisms involved in the burning process. The experimental work has been conducted using the FM Global Fire Propagation Apparatus (FPA) [ASTM E2058-03]. One of the benefits of using this experimental apparatus rather than the Cone Calorimeter is that it allows controlling the feed of heat and oxidizer to the reaction zone. The material chosen to conduct experiments on is a ternary smoke powder based on a mixture of starch and lactose as fuel components and potassium nitrate as oxidizer. This product is currently used by fire brigades to assess smoke venting systems efficiency of buildings. The kinetics associated with the combustion of the material was assessed slow enough to allow measuring instruments to capture the thermal and chemical evolution during combustion reaction. Thermal analysis has first been carried out by means of DSC, TGA, DTA, MS and FTIR data in order to understand the decomposition of the material and its energetic evolution when undergoing heating. However, if the latter methods help defining the decomposing path of the material, they do not provide an integral view of its combustion behaviour, in particular, the emissions of toxics which are kinetic path dependent. Subsequently, combustion tests have been carried out using the FPA. Its ability to capture the evolution of gases emissions formed during the reaction has been proved. The influence of two configuration parameters on the combustion behaviour and on the gaseous emissions of the material has been investigated. The proportion fuel/oxidizer has been varied as well as the composition of the reacting atmosphere. Results shows that the quantity of oxidizer in the material affects the kinetics of the reactions taking place in the condense phase. Increasing the concentration of potassium nitrate in the mixture enhanced the reaction rate of the smouldering combustion. Higher quantity of volatiles is released which favoured the initiation of a diffusion flame regime in the gaseous phase, above the sample. While the kinetics of the condense phase is governed by the oxidizer concentration, experiments show that the flaming regime is influenced by the concentration of oxygen (O2) in the reacting atmosphere. A transition from diffusion to premixed flame is found when the concentration of O2 surrounding the sample is reduced below 18%. An analytical model has been used to explain the existence of a transition for a critical O2 concentration. Finally, thermal and combustion analyses have allowed to characterise the behaviour of the material under critical conditions, in terms of decomposition taking place in the condense phase but also potential toxic emissions that can be released. Toxicity, kinetics, temperature evolution do not provide a complete view of the combustion phenomenon. Beside these elements that characterise the behaviour of a material for given conditions as well as also the degree of fire hazard encountered, the energetic issue holds as an essential feature that cannot be neglected. The heat release rate (HRR) is a critical parameter that defines a fire. It does not constitute an intrinsic material property but it describes the energetic response of the couple formed by the material and its environment. Oxygen Consumption calorimetry (OC) and Carbon Dioxide Generation calorimetry (CDG) are widespread methods to calculate the HRR resulting from a combustion reaction. Apparatuses such as the FPA or the cone calorimeter have already proved their potential to qualify the burning behaviour of common fuels in addition to polymers when their data are combined with an adapted calorimetric procedure. The same approach has been applied to energetic materials. However, prior to using these techniques, it is fundamental to have identified their restrictions. These techniques provide approximate estimations of the HRR. Results are affected by the propagation of uncertainties. Several sources of uncertainties can be found. One can cite: 1. Uncertainties associated with the sample material; 2. Uncertainties associated with the test conditions; 3. Uncertainties associated with the measurements; 4. Uncertainties associated with calculation assumptions. If uncertainties cannot always be estimated, the three first sources cited have received attention in the past from the scientific community, alike the last one. The restrictions associated with the assumptions developed for using the OC and CDG principles have to be clarified. The limits of validity of the hypotheses have to be clearly defined. In particular, the present dissertation questions the relevance of the energy constants that have been specified for OC and CDG as well as their related uncertainties. One of the purposes of the research deals with the ability to estimate accurate error bars for the calculation of the HRR. Once uncertainties related to the calorimetric methods are assessed, a method adapted from the basic OC and CDG principles is introduced that allows estimating the HRR of energetic materials. The approach is based on considering the chemical decomposition of the burning compound and defining a fictitious molecule for which energy coefficients can be calculated. Nevertheless, it requires the material to be known. Finally, the question of the advantage brought by these techniques over others, in terms of accuracy, is discussed within the framework of unconventional products, such as energetic materials or compounds whose composition is ignored. The results from this work will contribute to the development of fireanalysis methodologies and validate their use with energetic materials.