The work herein covers the complete process for development, production and testing of a melt processable pyrotechnic composition, with the goal of using the composition as a printing material in a fused deposition modelling (FDM) type 3D printer. 3D printing is fast becoming an area of interest for energetic materials research. This is due to the role that geometry can play in combustion performance of a composition and 3D printing’s ability to produce a variety of complex designs. Melt processable fluoropolymers were selected as oxidisers. The polymers selected for the study were FK-800® and Dyneon 31508®. Both are co-polymers of vinylidene fluoride (VDF) and chlorotrifluoroethylene (CTFE). Aluminium was the choice fuel in this instance as it had better energetic performance than the alternatives investigated. It was also deemed to be a safer fuel when considering the combustion products. Hazardous combustion products like hydrofluoric and hydrochloric acid could be suppressed by increasing the fuel loading to 30 wt.%, thereby reducing the risks associated with burning the composition. Preliminary differential thermal analysis (DTA) analysis indicated that the compositions would only ignite above 400 °C which was well above the suggested processing temperature of 230 °C as determined from thermogravimetric (TGA) analysis. These thermal analysis techniques indicated that the reactions were most likely a gas-solid reactions due to ignition temperatures being significantly lower than those associated with phase changes occurring in the fuels tested, yet above the decomposition temperatures for the oxidisers. ii Extrusion of the compositions proceeded with addition of LFC-1® liquid fluoroelastomer. This addition was made in order to order to lower the melt viscosity, thereby improving the quality of the filament produced. Compositions were extruded with an aluminium loading of 30 wt.%. Oxidiser and LFC-1® made up the rest of the mass with the LFC-1® contributions being either 7 wt.% or 14 wt.%. Burn rates, temperatures and ignition delays were all influenced by the addition of LFC-1® to the system. FK-800® was found to be a better oxidiser in this instance since its burn rates were consistent especially when compared to erratic nature of the Dyneon 31508® burns. Linear burn rates for the FK-800® increased from 15.9 mm·s−1 to 18.9 mm·s−1 with the increase in LFC-1® loading. Combustion temperature also increased by approximately 180 °C from 794 °C. Printing with the material was achieved only after significant alterations were made to the hot end used. Printing proceeded in a staged, start-stop manner. After each new layer of material was deposited the printer was cleared of material and the hot end was allowed to cool. If this procedure was not followed it led to significant preheating of the material within the feeding section of the extruder. This premature heating caused feeding problems due to softening and swelling of the material within the cold side of the hot end which led to blockages, leading to the conclusion that the composition was not compatible with the off-the-shelf hot end used in this study. Low quality printing could be achieved with both FK-800® and Dyneon 31508® compositions. This would suggest that slight compositional changes paired with the alterations made to the hot end could improve the quality of the prints to an extent that would be comparable to that of more commonplace printing materials. / Dissertation (MEng)--University of Pretoria, 2017. / Chemical Engineering / MEng / Unrestricted

The ignition temperature of the aluminium copper oxide (Al-CuO) thermite was measured using differential thermal analysis (DTA) at a scan rate of 50 °C/min in an inert nitrogen atmosphere. Thermite reactions are difficult to start as they require very high temperatures for ignition, e.g. for the Al-CuO thermite comprising micron particles it is ca. 940 °C. It was found that the ignition temperature is significantly reduced when the binary Si-Bi2O3 system is used as sensitiser. Further improvement is achieved when nano-sized particles are used. For the composition CuO + Al + Bi2O3 + Si (65.5:14.5:16:4 wt %), when all components except the aluminium fuel are nano-sized, the observed ignition temperature is reduced to ca. 615 °C and results in a thermal runaway. / Dissertation (MSc)--University of Pretoria, 2011. / Chemical Engineering / unrestricted

Silicon dispersions in water are used to produce pyrotechnic time delay compositions employed in mine detonators. The delay elements are manufactured by pressing the pyrotechnic composition into aluminium tubes. The automated filling and pressing process requires powders with good free-flow behaviour. Spray drying of water-based slurries is an appropriate method for obtaining such free-flowing granules as it creates almost perfectly spherical particle agglomerates. In addition to the acceptable flow properties, this process provides well-mixed compositions at desired particle size distributions. However, a potential hazard situation arises when water reacts dissociatively with silicon to form SiO2 and hydrogen gas according to Si + 2H2O _ SiO2 + 2H2↑. The propensity of the silicon to react with water and to release hazardous hydrogen gas must thus be suppressed. To this end, the following methods were investigated as a means of diminishing the rate of hydrogen evolution: (i) controlling the slurry pH; (ii) adding organic corrosion inhibitors; (iii) controlled silicon air oxidation before slurrying; and (iv) adding suitable metal ions to provide an additional cathodic reaction to that of water. The effect of organic surface modifications and medium pH on the rate of corrosion of silicon was studied at ambient temperature. It was found that the rate of hydrogen evolution increased with increasing pH. Silanes proved to be more effective silicon corrosion inhibitors than alcohols, with vinyl tris(2-methoxyethoxy) silane producing the best results from the silanes investigated. Differential thermal analysis (DTA) studies were performed using a near-stoichiometric amount of lead chromate as oxidant. Comparable combustion behaviour was observed when both the fuel and the oxidant powders were either uncoated or silane modified. Mixtures of neat oxidant with silane-coated silicon showed poor burn behaviour and this was attributed to poor particle- particle mixing due to the mismatch in surface energies. The controlled silicon air oxidation results showed that the best hydrogen evolution inhibition was attained upon formation of a SiO2 passivating layer at 350 °C. However, Fourier transform infrared (FTIR) data also suggest that some inhibition was imparted below 350 °C and this is due mainly to the removal of silicon surface hydroxyl groups rather than an increase in the SiO2 thickness. DTA studies performed using a nearstoichiometric amount of lead chromate revealed that although heat treatment at higher temperatures provides better passivation; it reduces the reactivity of the silicon in pyrotechnic compositions. The ignition temperature increases while the energy output decreases. Water oxidises silicon via an electrochemical reaction that produces hydrogen gas. The last approach considered in this study was the introduction of a competing cathodic reaction as a means of suppressing the liberation of hydrogen. It was found that the addition of metal ions with a higher reduction potential than hydrogen ions, e.g. copper (II) ions, reduced the amount of hydrogen liberated. In the presence of copper ions the reaction with water featured three distinct stages. During the initial stage, copper is deposited on the silicon and a rapid drop in solution pH is observed. Most of the hydrogen evolved during a second active stage, with the pH showing a slight upward drift. Finally, in the third stage, hydrogen evolution stopped as the silicon surface became passive. The reduction in the total hydrogen evolved was attributed to copper deposits reducing the active surface area available for the oxidation of silicon and to the presence of copper which facilitates accelerated passivation of the uncoated silicon surface. The nature of the anions present affected both the amount of copper deposited on the silicon and the amount of hydrogen released. DTA studies showed that exposure of silicon to copper metal salt solutions also decreases the reactivity of the silicon fuel in pyrotechnic compositions. Copyright / Dissertation (MSc)--University of Pretoria, 2012. / Chemical Engineering / unrestricted

In a push towards more environmentally friendly pyrotechnics, new greener pyrotechnic compositions need to be developed. A primary goal is to replace components such as lead, barium, and chromium in pyrotechnic compositions. Fused Deposition Modelling (FDM) is a 3D printing/additive manufacturing method whereby a thin filament is passed through a heated nozzle, and extruded onto a substrate in successive layers. This method of manufacturing could be used to produce pyrotechnic time delays based on suitable “green” polymer/fuel mixtures. Fluoropolymers are an attractive oxidising system for pyrotechnic use as fluorine is highly reactive and reacts relatively easily with common metallic fuels such as aluminium and magnesium to release a large amount of energy. Fluoropolymers are already in use as oxidisers and binders, especially in infrared decoy flares. PTFE has found wide use in the pyrotechnics industry, but is not melt-processible. A similar fluoropolymer, poly(chloro-trifluoroethylene) (PCTFE) was considered instead. PCTFE differs from PTFE in that one of the fluorine atoms in the TFE monomer has been replaced by a chlorine atom. The larger chlorine atom interferes with the packing of the polymer chains during polymerisation and, as such, may make it easier to process than PTFE. It was found that pure PCTFE degraded heavily during processing and was therefore precluded from any further study. Melt-processible copolymers containing PCTFE are available from industry. These copolymers contain vinylidene fluoride (VDF) in addition to the CTFE i.e. poly(CTFE-co-VDF). Two grades of copolymer were obtained from 3M: FK-800® resin and Dyneon® 31508 resin. These two polymers contain different ratios of CTFE to VDF. FK-800® resin was successfully extruded and showed minimal signs of degradation. Pyrotechnic films, containing aluminium powder as the fuel, were cast with both polymers using solvent techniques. Differential thermal analysis (DTA) was used to determine the ignition points of the compositions. All of the FK-800®-based compositions ignited at approximately 450 °C whilst all the Dyneon® 31508-based compositions ignited at approximately 400 °C. The energy output of the compositions was determined using bomb calorimetry. The experimental energy outputs of the FK-800®-based compositions correlated well with the predictions from the thermodynamic simulations. The maximum energy output, ~7.0 MJ∙kg1, occurred at a fuel loading between 30 – 35 wt.%. Except for one composition, the Dyneon® 31508-based compositions did not ignite in the bomb calorimeter. FK-800® was successfully extruded into a filament and showed minimal signs of degradation. In order to assess the impact of adding a solid filler on the mechanical properties and extrudability of the polymer, magnesium hydroxide was used as inactive model compound in place of aluminium. A filament of FK-800® and Mg(OH)2 was successfully compounded and produced using a filler loading of 30 wt.%. Compounding of the Dyneon 31508® with the magnesium hydroxide was unsuccessful. Addition of LFC-1® liquid fluoroelastomer improved the processibility of the Dyneon 31508® by lowering the melt viscosity. / Dissertation (MEng)--University of Pretoria, 2017. / Chemical Engineering / MEng / Unrestricted

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This thesis presents detailed description of the development of two computer codes written in FORTRAN language for the analysis of detonation of energetic mixtures. The first code, named GasPX, can compute the detonation parameters of premixed gaseous mixtures and the second one, named BARUT-X, can compute the detonation parameters of C-H-N-O based solid explosives. Both computer codes perform the computations on the basis of Chapman-Jouguet Steady State Detonation Theory and in chemical equilibrium condition. The computed detonation point by the computer codes is one of the possible solutions of the Rankine&ndash / Hugoniot curve and it also satisfies the Rayleigh line. By examining the compressibility of the gaseous products formed after detonation of premixed gaseous mixtures, it is inferred that the ideal-gas equation of state can be used to describe the detonation products. GasPX then calculates the detonation parameters complying with ideal-gas equation of state. However, the assumption of the ideal gas behavior is not valid for gaseous detonation products of solid explosives. Considering the historical improvement of the numerical studies in the literature, the BKW (Becker-Kistiakowsky-Wilson) Equation of State for gaseous products and the Cowan &amp / Fickett Equation of State for solid carbon (graphite) in the products are applied to the numerical model of BARUT-X. Several calculations of detonation parameters are performed by both GasPX and BARUT-X. The results are compared with those computed by the other computer codes as well as the experimental data in the literature. Comparisons show that the results are in satisfactory agreement with experiments and also in good agreement with the calculations performed by the other codes.

This Master thesis describes the design and implementation of particle system and a user interface of tool for fireworks design and simulation. The engine uses an XNA framework and an HLSL shading language. The thesis also compares applications focused on designing and simulation of fireworks. Applicability and demandings of applications for designing and simulation of fireworks  among Czech and Slovak companies  dealing professionally with firework  are  analysed as well.

La pollution atmosphérique, et plus particulièrement la pollution particulaire d’origine anthropique constitue l'un des facteurs de risque environnemental les plus importants impliqués dans l’augmentation croissante de la morbi-mortalité liée aux pathologies respiratoires et cardio-vasculaires. Au coeur du domaine qu’englobent les activités pyrotechniques, que ce soit dans le domaine professionnel, civil ou militaire, les fumigènes sont référencés comme producteur important de particules et jouent donc un rôle non négligeable dans l’augmentation de cette pollution particulaire, exposant leurs utilisateurs aux différents aérosols émis.L’objectif général de cette étude exploratoire a été d’apporter des connaissances sur les caractéristiques physico-chimiques ainsi que sur la toxicité pulmonaire in vitro de particules émises lors d’activités pyrotechniques, et plus précisément de particules issues d’armes de petit calibre et de fumigènes.La caractérisation physico-chimique a démontré les particules de tir possédaient une granulométrie assez grossière (entre 3 et 7,5 μm) et étaient composées majoritairement d’éléments métalliques ; contrairement aux particules de fumigène qui appartiendraient à la classe granulométrique des particules fines (< 0,95 μm) et qui seraient majoritairement composées de molécules organiques différentes selon le type de fumigène. L’évaluation de la toxicité a été réalisée par une approche in vitro en utilisant des cellules épithéliales alvéolaires humaines (A549) exposées aux particules de tir et de fumigènes. Une étude de mutagénicité a été conduite à partir d’extraits organiques des particules de fumigènes. Parmi les particules testées, les particules de tir et du fumigène 1 ont induit une cytotoxicité. Les particules de fumigène 1 ont également induit un stress oxydant (augmentation de l’expression de l’ARNm de HO-1), une initiation de la réponse inflammatoire (augmentation de l’expression de l’ARNm d’IL-6 et IL-8) et des effets mutagènes.Les résultats de cette étude comparative ont démontré que les particules issues d’armes de poing et de fumigènes avaient une granulométrie, une concentration atmosphérique ainsi qu’une composition chimique différentes ; caractéristiques physico-chimiques responsables d’effets mutagènes et cytotoxiques différents ainsi que d’altérations des propriétés oxydantes et inflammatoires intrinsèques. Cette étude a mis en évidence la nécessité d’évaluer la toxicité des particules issues d’activités pyrotechniques en développant des moyens expérimentaux adaptés, depuis la collecte des particules jusqu’à l’évaluation de leurs impacts sanitaires. / Air pollution, and particulary anthropogenic particulate matter, is one of the most important risk factors involved in the high rate of morbidity and mortality related to respiratory and cardiovascular diseases. In pyrotechnic field, be it professional, civil or military activities, smokes constitue an important particle producer playing a major role in particulate matter emmergence and thereby exposing users to the various emitted aerosols.The main purpose of this exploratory study was to provide knowledge on the physicochemical characteristics of particles emitted during pyrotechnic activities, more specifically particles from gunfire and smokes, and to assess their pulmonary toxicity in vitro.On the first hand, the physicochemical characterization demonstrates that firing particles had a rather coarse granulometry (3 to 7.5 μm) and were mainly composed of metallic elemets, despite smoke particles belong to the category of fine particles (< 0,95 μm) and are predominantly composed of different organic molecules according to the smoke type.On the other hand, in order to assess the pulmonary toxicity of particles, we exposed human alveolar epithelial cells (A549) in vitro to particles coming from either gunfire and to two of the four different smokes (smoke 1 and 4). The results of this study showed that some of these particles (gunfire and smoke 1 particles) induced a mutagenic effects from organic extracts, as well as cytotoxicity. Moreover, particles of smoke 1 were also able to give rise to an oxidative stress (increased HO-1 mRNA expression) and to initiate an important inflammatory response characterized by pro-inflammatory cytokine upregulation (increase in IL-6 and IL-8 mRNA expression).The results of this comparative study demonstrated that particles from gunfire and smoke have different particle sizes and chemical composition. These physicochemical characteristics are responsible for different mutagenic and cytotoxic effects as well as alterations of the intrinsic oxidizing and inflammatory properties. This study also made it possible to understand the different methods of toxicological evaluation of smoke particles.

Répondant à un besoin grandissant de standardisation et d’adaptabilité pour les systèmes pyrotechniques, nous présentons au travers de ce travail un nouveau concept de leurre infrarouge intelligent, contrôlable à l’aide d’un système d’initiation électronique miniature embarqué. Notre solution innovante se décompose en trois blocs fonctionnels distincts : (1) un bloc d’éjection pyrotechnique contrôlable intégrant trois charges d’éjection dans une seule pièce plastique métallisée, (2) un bloc appelé fonction terminale, constitué d’un pain pyrotechnique infrarouge structuré, couplé à un étage de micro-initiation à base de nano-thermites, adressable et basse énergie, et (3) un bloc de contrôle, connecté et autonome, répondant au STANAG 4187 qui commande l’armement et la mise à feu des fonctions pyrotechniques. Au cours de ce travail, nous avons développé un code de balistique intérieure à paramètres globaux et un superviseur d’optimisation, capable de simuler n’importe quel système à effet mortier, et un code de régression géométrique basé sur la méthode level-set,capable de modéliser la combustion de n’importe quel pain solide multicomposition, compartimenté ou structuré, allumé séquentiellement ou simultanément en plusieurs points.Nous avons montré théoriquement, puis validé expérimentalement, qu’il était possible de contrôler finement la réaction de combustion des pains pyrotechniques IR grâce à un allumage séquentiel de ces derniers, ce qui représente une innovation importante en pyrotechnie. Nous avons validé expérimentalement, qu’il était possible de contrôler la vitesse d’éjection de leurres IR grâce à un allumage partiel d’impulseurs plastroniques. Ce travail a abouti à l’intégration des différents blocs fonctionnels dans un démonstrateur représentatif d’un leurre infrarouge intelligent et miniature : CASSIS. / Answering a growing need for standardization and adaptability in pyrotechnics, we hereby present a smart and safe pyrotechnical infrared (IR) flare electronically controllable through an embedded miniature initiation system. The countermeasure has been designed to fit within a 1”×1”×8” standard cartridge, and consists of three distinct blocks, which are mechanically and electronically interconnected: (1) a pyrotechnical ejection block integrating three ejection charges in a single metalized plastic casing, (2) a micro-initiation stage comprising nanothermite-based micro-initiators and a structured pyrotechnic loaf, (3) a STANAG 4187 compatible electronic control, command and power management block.Throughout this work, we developed a lumped parameter internal ballistics model for the ejection, and conducted a response surface methodology study to extract optimal design parameters. We developed a geometric regression script, based on level set techniques, to model the combustion of multicomponent, sequentially-initiated, partially inerted pyrotechnic loafs. We demonstrated, theoretically then experimentally, that we could control the combustion of IR pyrotechnic loaves using sequential initiation, and that we could control the ejection velocity of IR flares using multipoint mortar ejectors.This work resulted in integrating said technological block in a functional 1’’1’’8’’ controllable, autonomous safe and smart infrared flare demonstrator, CASSIS.

Despite advancements in the analysis of statnamic load testing data, there exists uncertainty with underlying procedural assumptions. Two such assumptions are that the system mass and soil-related damping coefficient remain constant throughout the loading event. These assumptions are the culprit of aberrant predictions of the static capacity at small displacements when the overall displacement is large. An exploration of the assumptions may validate prior existing test results as well as solidify the current analysis process. However, an exploration could also reveal an overestimation or underestimation of portions of the predicted static load responses. The testing program outlined herein consists of a two-phase sequential agenda devoted toward the preparation and familiarization of a new laboratory statnamic device. The first phase involves the development of user guidelines for accurately targeting a desired statnamic test, and the second incorporates the guidelines into a preliminary testing regime specifically targeted at determining a suspected strain-dependant statnamic damping coefficient. The steps taken in this thesis are intended to launch future research endeavors toward obtaining a better understanding of the statnamic damping coefficient.