No description available.

A low cost Cook-Off experimental facility has been established to provide a convenient method of ranking explosives in their response to Cook-Off by the time to event under two widely different heating rates and at two different scales. This thesis describes the literature review undertaken as preparation for the purposed study and all the experimental work developed comprising the design of the trials vehicles, the demonstration of their suitability for Fast and Slow Cook-Off trials with confined explosive systems, the preparation of the samples and test vehicles to be trialled as well as the set-up of adequate facilities to undertake the scheduled firing programme. Results are reported for Cook-Off tests on TNT, RDX, and their mixtures. The emphasis of the study is on time to event, and temperature at event, and in addition a qualitative assessment of the violence of the event was made by examination of the fragments of the vehicles, although it is accepted that the relatively light and low cost design of the vehicle may lead to variable confinement in the early stages of the explosive event, and hence to a wider spread of responses than would be obtained from a more heavily confined and more costly vehicle. The test vehicles give results, which differentiate between the various explosives and explosive mixtures trialled and between the scales. More experiments are required to establish the reproducibility of the measurements. The design of the equipment makes this a relatively inexpensive undertaking. The experiment was modelled using published kinetic data, but the calculated time to event differed from that observed to different extents at the two scales. It is hypothesised that the mechanism may change over the prolonged heat soaks and that quantitative scaling is not possible with the available information. Further work is also suggested using a different type of Cook-Off test vehicle, which will in our opinion reduce even further the cost of Cook-Off testing, due to reduction in man-hours of preparation involved and manufacture cost of the Cook-Off test vehicles, and consequently of ranking of explosives.

A low cost Cook-Off experimental facility has been established to provide a convenient method of ranking explosives in their response to Cook-Off by the time to event under two widely different heating rates and at two different scales. This thesis describes the literature review undertaken as preparation for the purposed study and all the experimental work developed comprising the design of the trials vehicles, the demonstration of their suitability for Fast and Slow Cook-Off trials with confined explosive systems, the preparation of the samples and test vehicles to be trialled as well as the set-up of adequate facilities to undertake the scheduled firing programme. Results are reported for Cook-Off tests on TNT, RDX, and their mixtures. The emphasis of the study is on time to event, and temperature at event, and in addition a qualitative assessment of the violence of the event was made by examination of the fragments of the vehicles, although it is accepted that the relatively light and low cost design of the vehicle may lead to variable confinement in the early stages of the explosive event, and hence to a wider spread of responses than would be obtained from a more heavily confined and more costly vehicle. The test vehicles give results, which differentiate between the various explosives and explosive mixtures trialled and between the scales. More experiments are required to establish the reproducibility of the measurements. The design of the equipment makes this a relatively inexpensive undertaking. The experiment was modelled using published kinetic data, but the calculated time to event differed from that observed to different extents at the two scales. It is hypothesised that the mechanism may change over the prolonged heat soaks and that quantitative scaling is not possible with the available information. Further work is also suggested using a different type of Cook-Off test vehicle, which will in our opinion reduce even further the cost of Cook-Off testing, due to reduction in man-hours of preparation involved and manufacture cost of the Cook-Off test vehicles, and consequently of ranking of explosives.

The novel candidate high energy insensitive explosive; 2,5-diamino-3,6-dinitropyrazine (ANPZ-i) has been prepared in acceptable overall yield. ANPZ-i was synthesised by the nitration of 2,5-diethoxypyrazine using nitronium tetrafluoroborate (NO2+BF4-) in sulfolane and the subsequent amination of 2,5-diethoxy-3,6-dinitropyrazine, under autoclave conditions. Oxidation studies towards the dioxide derivative of ANPZ-i, 2,5-diamino-3,6-dinitropyrazine-1,4-dioxide (PZDO), were unsuccessful. The synthesis of existing high explosives; 2,6-diamino-3,5-dintropyrazine (ANPZ) and 2,6-diamino-3,5-dinitropyrazine-1-oxide (PZO) has been scaled up to produce approximately 25 g batches of material. A number of novel nitrations using NO2+BF4- have been carried out on a range of chloro-, methyl- and hydroxy-functionalised quinoxalines and quinazolines. A range of novel functionalisations have also been carried out on the platform molecule; 2,4-diamino-6,8-dinitroquinazoline giving rise to 2,4-diamino-6,8-dinitroquinazoline-1,3-dioxide (di-N-oxidation product), 2,4,7-triamino-6,8-dinitroquinazoline (monoamination product) and 2,4,6,8-tetra-aminoquinazoline (dihydrogenation product). Detonics molecular modelling was carried out on the following target molecules: 2,5-diamino-3,6-dinitropyrazine-1,4-dioxide (PZDO), 2,5,8-triamino-3,6,7-trinitroquinoxaline-1-oxide and 2,5,7-triamino-4,6,8-trinitroquinazoline-1-oxide. The detonation velocity of the new explosive molecule; 2,5-diamino-3,6-dinitropyrazine (ANPZ-i) was calculated and it was found to be a similar value to that obtained experimentally for the existing high explosive RDX. Calculation by molecular modelling of the steric energies of ANPZ, PZO, ANPZ-i and PZDO gave a quantitative assessment of the difficulty in oxidising ANPZ-i to give PZDO. Extensive analysis of carbon-13 NMR spectroscopy shift values was carried out for approximately twenty nitrogen heterocyclic compounds. Comparison of shift values indicated consistency in the interpretations. On-line literature searches have shown that the following compounds prepared in this project are new: 2,3,6-trichloro-5-nitroquinoxaline, 2,3-dimethoxy-6,7-dinitroquinoxaline, 2,3,6-trichloroquinoxaline-1-oxide, 2,4-diamino-6,8-dinitroquinazoline-1,3-dioxide, 2,4,7-triamino-6,8-dinitroquinazoline and 2,5-diamino-3,6-dinitropyrazine (ANPZ-i). Furthermore, new synthetic routes have been used in the preparation of the following compounds: 2,3-dichloro-5-nitroquinoxaline, 2,3,6,7-tetrachloro-5-nitroquinoxaline, 2-hydroxy-6-nitroquinoxaline, 2-hydroxy-3-methyl-6-nitroquinoxaline and 2,5-diethoxy-3,6-dinitropyrazine.

In order to effectively model the behaviour of energetic materials under operational conditions it is essential to obtain detailed structural information for these compounds at elevated temperature and/or pressures. The structural characterisation of the high explosives RDX and CL-20 and a series of inorganic azides [Mn+(N3)n] at extreme conditions is described herein. In addition to the characterisation of a highly metastable β -form of RDX (1,3,5- trinitrohexahydro-1,3,5-triazine) at atmospheric pressure, the structure solution of a high-pressure/ high-temperature polymorph is described. This form, obtained above 4.3 GPa and 450 K, has been shown to be distinct from the β -form and has therefore been denoted - RDX. Furthermore, ε -RDX is sufficiently metastable to allow its recovery to ambient pressure at 150 K; it only transforms to the α -form upon warming to 230 K. Finally, the ambient-temperature compression of RDX has been investigated to a maximum pressure of 23.0 GPa, using methanol:ethanol (4:1) as the pressure-transmitting medium; no phase transition was observed under these conditions, other than the α → γ transition at 3.9 GPa. The structure of a high-pressure polymorph of CL-20 (2,4,6,8,10,12- hexanitrohexaazaisowurtzitane) has also been determined by a combination of powder and single-crystal X-ray diffraction. Compression of γ -CL-20 to above 0.7 GPa using Fluorinert (FC-77) as the pressure-transmitting medium results in a phase transition to the ζ -form, which has been found to display structural similarities with both theγ γ - and ε -forms. The high-pressure behaviour of CL-20, however, depends markedly on the starting polymorph and the pressure-transmitting medium selected. Compression of γ -CL-20 in MeOH:EtOH (4:1) results in the formation of a 2:1 CL-20:MeOH solvate at 0.5 GPa. This solvate is stable upon compression to P > 5.0 GPa. It may also be recovered to ambient pressure at 293 K. Meanwhile, no phase transition is observed during the compression of ε -CL-20 to a maximum pressure of 7.2 GPa. Finally, a series of inorganic azides [NaN3, CsN3, TlN3, NH4N3, AgN3 and Pb(N3)2] has been characterised under a range of pressure and temperature conditions. Of the six compounds studied, all displayed at least one polymorphic transition – 5 new forms have been structurally characterised in this work and evidence of another 5 is presented. The combined effect of pressure and temperature results in sodium azide adopting a tetragonal structure common to larger alkali metal azides. Caesium azide has been shown to undergo three phase transitions during compression to 6.0 GPa – the structure of the first high-pressure form is reported. A variable temperature X-ray powder diffraction study of TlN3 has allowed the structural characterisation of the low-temperature TlN3-IV (at 230 K) as well as providing evidence for a phase transition to a high-temperature form above 550 K. The high-pressure form III (obtained above 0.76 GPa) has also been determined by neutron powder diffraction. Silver, ammonium and lead(II) azides have all been shown to undergo a phase transition at high pressures. Compression of silver azide (P > 0.80 GPa) removes an orthorhombic distortion observed at atmospheric pressure, resulting in the tetragonal structure adopted by CsN3 and TlN3 under ambient conditions. Moreover, NH4N3 and Pb(N3)2 have been found to undergo phase transitions at 2.6 GPa, although their high-pressure structures have still to be determined.

<div>With an eye towards applications such as the selective sensing of volatile organic compounds (VOCs) or micro-scale thrust generation, inkjet printing was explored as a means to selectively deposit functional materials. The work detailed herein explores a series of fundamental steps to gain expertise related to the piezoelectric inkjet printing of functional materials. The successful printing of nanothermite was demonstrated with two unique printing techniques. Furthermore, the integration of this material with an ignition mechanism was shown to create a fully printed igniter energetic system. These advancements support future work related to the printing of other energetic materials necessary to create tunable reactive systems. This knowledge was then translated into the development of resonant mass sensing devices that are selectively functionalized using inkjet printing. This approach to functionalization allowed for the precise deposition of receptive chemistries on devices resulting in selective, highly-sensitive devices that successfully detected biomarkers secreted after traumatic brain injuries and harmful VOCs. This work implemented oscillator-based sensors to achieve a low-cost, low-power sensor platform with redundant elements. Furthermore, the predictive capabilities of these devices were explored using least squares and linear regression modeling.</div>

Following several terrorist attacks that have occurred during this decade, there is an urgent need to develop new technologies for the detection of highly energetic materials that can represent an explosive hazard. In an effort to contribute to the development of these new technologies, this work presents the design aspects of a chip-scale calorimeter that can be used to detect an explosive material by calorimetric methods. The aim of this work is to apply what has been done in the area of chip-scale calorimetry to the screening of highly energetic materials. The prototypes presented here were designed using computer assisted design and finite element analysis tools. The design parameters were set to satisfy the requirements of a sensor that can be integrated into a portable system (handheld) for field applications. The design approach consisted of developing a sensor with thick silicon membranes that can hold micro-size samples and that can operate at high temperatures, while keeping the cost of the sensor low. Contrary to other high resolution systems based on thin-film membranes, our prototypes exhibit a contribution from addenda that is comparable to that from the sample, and hence they have lower sensitivity. However, using thick membranes offers the advantage of producing sensors strong enough for this application and that have significantly lower cost. Once the prototypes were designed, the fabrication was performed using standard microfabrication techniques. Finally, the operation of our prototypes was demonstrated by conducting thermal analysis of different liquid and solid samples.

Energetic materials comprise a set of systems of tremendous technological importance. Besides helping shape landscapes to establish communications, they have been used to reach fuel reservoirs, deploy safety bags and prevent heart strokes. Understanding its behavior can help in attaining strategic and tactical superiority, and importantly, preserve lives of people who handle these materials. The large discrepancy in length and time scales at which characteristic processes of energetic materials are of relevance pose a major challenge for current simulation techniques. We present a systematic study of crystalline energetic materials of different sensitivity and analyze their properties at different theoretical levels. Equilibrium structures, vibrational frequencies, conformational rearrangement and mechanical properties can be calculated within the density functional theory and molecular dynamics at finite temperatures. We have found marked differences in the calculated properties in systems with ranging sensitivities. Reactions at elevated temperatures have been studied using ab initio molecular dynamics method for crystals of nitroethane. Furthermore, while presenting the state of the art of energetic materials modeling, the limitations of each methodology are also discussed. Prospective systems and an elasticity driven approach that can be applied to other type of materials is also presented.

Reactive chemicals are presented widely in the chemical and petrochemical process industry. Their chemical reactivity hazards have posed a significant challenge to the industries of manufacturing, storage and transportation. The accidents due to reactive chemicals have caused tremendous loss of properties and lives, and damages to the environment. In this research, three classes of reactive chemicals (unsaturated hydrocarbons, self-reacting chemicals, energetic materials) were evaluated through theoretical and experimental methods. Methylcyclopentadiene (MCP) and Hydroxylamine (HA) are selected as representatives of unsaturated hydrocarbons and self-reacting chemicals, respectively. Chemical reactivity of MCP, including isomerization, dimerization, and oxidation, is investigated by computational chemistry methods and empirical thermodynamic–energy correlation. Density functional and ab initio methods are used to search the initial thermal decomposition steps of HA, including unimolecular and bimolecular pathways. In addition, solvent effects are also examined using water cluster methods and Polarizable Continuum Models (PCM) for aqueous solution of HA. The thermal stability of a basic energetic material, Nitroethane, is investigated through both theoretical and experimental methods. Density functional methods are employed to explore the initial decomposition pathways, followed by developing detailed reaction networks. Experiments with a batch reactor and in situ GC are designed to analyze the distribution of reaction products and verify reaction mechanisms. Overall kinetic model is also built from calorimetric experiments using an Automated Pressure Tracking Adiabatic Calorimeter (APTAC). Finally, a general evaluation approach is developed for a wide range of reactive chemicals. An index of thermal risk is proposed as a preliminary risk assessment to screen reactive chemicals. Correlations are also developed between reactivity parameters, such as onset temperature, activation energy, and adiabatic time to maximum rate based on a limited number, 37 sets, of Differential Scanning Calorimeter (DSC) data. The research shows broad applications in developing reaction mechanisms at the molecular level. The methodology of reaction modeling in combination with molecular modeling can also be used to study other reactive chemical systems.

Recently, the use of thermite-based pressure waves for applications in cellular transfection and drug delivery have shown significant improvements over previous technologies. In the present study, a new technique for producing thermite-generated pressure pulses using fully-dense nano-scale thermite mixtures was evaluated. This was accomplished by evaluation of a stoichiometric mixture of aluminium (Al) and copper(II)-oxide (CuO) prepared by mechanical alloying. Flame propagation speeds, constant-volume pressure characteristics and underwater pressure characteristics of both a micron-scale and mechanically alloyed mixture were measured experimentally and compared with conventional nano-scale thermites. It was determined that mechanically alloyed mixtures are capable of attaining flame propagation speeds on the same order as nano-scale mixtures, with flame speeds reaching as high as approximately 100 m/s. Constant-volume pressure experiments indicated that mechanically alloyed mixtures result in lower pressurization rates compared with conventional nano-scale mixtures, however, an improvement by as much as an order of magnitude was achieved compared with micron-scale mixtures. Thermochemical equilibrium predictions for pressures observed in constant-volume reactions were found to capture relatively well the equilibrium pressure for both low and high values of relative density. Generally, the predictions over-estimated the measured pressures by approximately 60%. Results from underwater experiments indicated that the mechanically alloyed samples produced peak shock pressures and waveforms similar to those for a nano-scale Al-Bi2O3 mixture reported by Apperson et al. (2008). In an effort to model the pressure signal obtained from the underwater reaction, calculations were performed based on the rate of expansion of the high pressure gas sphere. Predicted pressures were found to agree fairly well in terms of both the peak pressure and pressurization rate. The present study has thus identified the ability for mechanically alloyed thermite mixtures to produce underwater pressure profiles that may be conducive for applications in cellular transfection and drug delivery. Récemment, l'utilisation d'ondes de pression produite par des mélanges de thermite pour des applications dans la transfection cellulaire et l'administration de médicaments ont démontré des améliorations importantes par rapport aux technologies précédentes. Dans l'étude ci jointe, une nouvelle technique pour produire des impulsions de pression générée par un mélange thermite, soumit a de l'alliage mécanique, a été évaluée. Ceci a été accompli par l'évaluation d'un mélange stoechiométrique d' aluminium (Al) et de l'oxyde de cuivre(II) (CuO), préparé par mécanosynthèse. Les vitesses de propagation de la flamme, les caractéristiques de pression pour la combustion à volume constant et les caractéristiques de pression pour la combustion sous l'eau ont été mesurées expérimentalement et comparés avec les thermites conventionnel à l'échelle nano. Nous avons déterminé que les mélanges alliés mécaniquement sont capables d'atteindre des vitesses de propagation de flamme du même ordre que les mélanges à l'échelle nanométrique, atteignant jusqu'à environ 100 m/s. Les expériences de combusition à volume constant, indique que les mélanges alliés mécaniquement induit des taux de pressurisation inférieures à celles des mélanges de nano-échelle conventionnel, cependant, une amélioration de près d'un ordre de grandeur a été atteint par rapport aux mélanges d'échelle micronique. Prédictions thermochimiques des pression de compbustion se sont révélés capable de relativement bien saisir les valeurs observées dans les expériences à volume constant. En règle générale, les prévisions sur-estimé les pressions mesurées par environ 60%. Les résultats des expériences sous-marines ont indiqué que les échantillons alliés mécaniquement ont produit des pressions et des profils d'onde similaires à celles produit par un mélange de Al-Bi2O3 de nano-échelle, comme indiqué par Apperson et al. (2008). Pour modéliser les pressions obtenues dans les expériences sous-marines, des calculs basés sur le taux d'expansion de la bulle de gaz à haute pression ont été obtenus. Les pressions prédites ont été trouvés d'être relativement en accord avec la pression maximale et le taux de pressurisation observé. Cette étude a ainsi identifié la possibilité pour l'utilisation des mélanges de thermites alliés mécaniquement pour produire des profils de pression sous l'eau propices pour des applications de transfection cellulaire et l'administration de médicaments.