<p dir="ltr">Reaction zone thickness directly affects detonation properties such as detonation velocity and critical diameter. It is hypothesized that the effective reaction zone thickness is influenced by the particle size distribution and solids loading (wt.%) (solids loading) of an explosive material. In this study, we test several paste extrudable explosive (PEX) samples, to study the effects that varying particle size distribution and solids loading have on detonation properties. The PEX samples are based on four different explosives (RDX, PETN, HMX and DAAF), created by suspending explosive particles of different size distributions within an inert binder. A novel half- cone geometry is used to test the samples allowing for the capture of detonation speed (using a high-speed camera) and failure thickness data, by using the polycarbonate half-cone as a witness plate. Using this data, we create a diameter effect curve for each of the samples, allowing us to indirectly compare relative reaction zone thicknesses by measuring the slope of the linear region of the plots. Data found in open literature was compared to the PEX samples used in this study, but data was scarce. This study hopes to narrow the gap found in open literature.</p>

This thesis explores the development of direct electrochemical reduction as a means of providing primary treatment of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in a manufacturing process waste stream. An industrial process wastewater laden with RDX was successfully treated in small batch reactors. Reaction kinetics were used to design a proof of concept bench scale flow reactor that utilized parallel packed electrode plates. Following successful testing of this reactor, a pilot scale packed electrode flow reactor was built. The reactor performance as a function of residence time was fit by a first order decay equation. Greater than 97% reduction of RDX in a process wastewater was observed at a reactor residence time of 27 minutes. The work presented herein was successful in creating an electrochemical treatment system capable of removing RDX from an industrial process waste stream with no chemical addition, and without creating an additional hazardous waste stream.

The affects of hydrodynamic shock wave treatment on the bacterial flora of raw beef and poultry were evaluated. Hydrodynamic shock waves were generated in an aqueous treatment medium by either the detonation of two types of explosive charges (explosively-generated hydrodynamic shock waves [EHSW]) (a binary or a molecular explosive) or by electrical discharge (high voltage arc discharge Hydrodyne (TM [HVADH; Hydrodyne, Inc.]). A variety of sample types (whole steaks, ground beef, a water and ground beef slurry) were used to determine the lethality affects of EHSW on cells of the marker microorganism Listeria innocua suspended in a simple broth medium. These sample types were used in order to evaluate the affects of the process not only on the surface, but throughout the bulk of the samples in order to determine whether EHSW could also be used as a non-thermal alternative to reduce the bacterial flora of non-intact or ground meats. The levels of psychrotrophic, lactic, and coliform populations on the surface of whole eye of round steaks submitted to EHSW processing did not differ (P> 0.05) from those of untreated whole eye of round steaks. Parameters expected to influence the nature, magnitude, and propagation of the hydrodynamic shock wave were also varied and evaluated in order to determine which individual parameter or combination of parameters affected the bactericidal potential of EHSW or HVADH processing. Treatment with EHSW failed (P > 0.05) to produce lethality effects on the psychrotrophic, lactic, and coliform populations of ground beef, regardless of the composition and mass of explosive used, the number of successive EHSW treatments used, the relative distance between the explosive charge and the top surface of the sample, or the temperature of the water used in the treatment chamber. EHSW processing did not change (P >0.05) the bacterial population of treated ground beef samples when compared to untreated controls during a five day refrigerated storage study. No lethality effects were observed (P >0.05) in ground beef samples treated by HVADH when samples were subjected to one, two, or three successive HVADH treatments. Minimal penetration of surface inoculated bacteria was observed for both beef steaks and boneless skinless chicken breasts subjected to EHSW and HVADH, respectively. In EHSW-treated beef eye of round steaks, marker bacteria were detected within the first 300 um of tissue below the inoculated surface, 50-100 um beyond the depth of untreated surface inoculated steaks. In HVADH-treated boneless skinless chicken breasts, marker bacteria were detected within the first 200 um below the inoculated surface, 50-100 um beyond the depth of untreated surface inoculated boneless skinless chicken breasts. This suggests that although no difference in the bacteriological populations was observed between EHSW treated, HVADH treated, and untreated control samples of whole steaks (and ground beef treated with both HVADH and EHSW), HVADH and EHSW treatments affect the movement of surface bacteria. United States Department of Agriculture (USDA) guidelines suggest intact beef steaks be cooked to achieve a cooked color appearance on the surface and raw poultry be cooked to an internal temperature of 77° C to inactivate the pathogens Escherichia coli O157:H7 and salmonellae which are of concern in beef and poultry, respectively. By following these guidelines during proper cooking, consumers achieve thermal inactivation of these pathogens. Since the movement of the marker bacterium observed in treated steaks and boneless skinless chicken breasts was minimal, proper cooking of the products would be expected to inactivate vegetative bacterial cells at this depth. Therefore, EHSW and HVADH treated whole beef steaks and boneless skinless chicken breasts would not be expected to pose a bacterial hazard if the products were properly cooked. / Ph. D.

Terahertz (THz) wavelengths have attracted recent interest in multiple disciplines within engineering and science. Situated between the infrared and the microwave region of the electromagnetic spectrum, THz energy can propagate through non-polar materials such as clothing or packaging layers. Moreover, many chemical compounds, including explosives and many drugs, reveal strong absorption signatures in the THz range. For these reasons, THz wavelengths have great potential for non-destructive evaluation and explosive detection. Three-dimensional (3-D) reflection imaging with considerable depth resolution is also possible using pulsed THz systems. While THz imaging (especially 3-D) systems typically operate in transmission mode, reflection offers the most practical configuration for standoff detection, especially for objects with high water content (like human tissue) which are opaque at THz frequencies. In this research, reflection-based THz synthetic-aperture (SA) imaging is investigated as a potential imaging solution. THz SA imaging results presented in this dissertation are unique in that a 2-D planar synthetic array was used to generate a 3-D image without relying on a narrow time-window for depth isolation [1]. Novel THz chemical detection techniques are developed and combined with broadband THz SA capabilities to provide concurrent 3-D spectral imaging. All algorithms are tested with various objects and pressed pellets using a pulsed THz time-domain system in the Northwest Electromagnetics and Acoustics Research Laboratory (NEAR-Lab).

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.

No description available.

<p>The transformation of mechanical energy into thermal energy within composite energetic materials through various thermomechanical mechanisms is thought to lead to the creation of localized areas of intense heating. The growth of these “hot spots” is responsible for the bulk reaction or decomposition of the energetic material. Understanding the formation and growth of these hot spots has been an active area of research particularly for high-speed impact and shock conditions, but further work remains to be done in particular with respect to hot spot formation due to periodic mechanical excitation. Previous literature has established that many potential thermomechanical mechanisms may act at the interface between the constituent components of a composite energetic material. In order to provide further insight and guidance into the design of safer and more resilient energetic materials, the role of adhesion on hot spot formation for polymer bonded explosives (PBXs), a subset of composite energetic materials, was explored. Single HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocane) crystals in polymer blocks were subjected to ultrasonic excitation and subsequent heating was captured via infrared thermography. Subsequent testing of HMX PBXs using a drop weight tower captured changes in the sensitivity of the energetic material. Variation of the polymer binder allowed for a range of adhesive and mechanical properties to be examined. These experiments on the role of adhesion under these kinds of excitations provided insight into how mechanical energy is being transformed into localized heating.</p>

<p> </p> <p><em>Improvised explosive devices (IEDs) are a global threat due to their destructive potential, the easy access to raw materials, and online instructions to manufacture them. These circumstances have led to an increase in the number of IEDs using potassium chlorate as an oxidizer. The standard methods to detect chlorate are mainly designed for laboratory-only testing. Thus, field instrumentation capable of detecting oxidizers from explosives fuel-oxidizers is critical for crime scene investigation and counterterrorism efforts (described in Chapter 1). We developed a paper-based sensor for the in-field detection of chlorate (described in Chapter 2). The sensor is low-cost, disposable, portable, and inexpensive to fabricate, and its flexibility features allow for surface sampling without sample destruction. The sensor has an electrodeposited molybdate sensing layer, as chlorate was reported to have a catalytic effect on the molybdate reduction. The chlorate detection relies on monitoring the change in redox activity of the molybdate sensing layer using different electroanalytical techniques. We effectively demonstrated the analytical performance of the sensor (Chapter 3), obtaining a limit of detection of 1.2 mM and a limit of quantification of 4.10 mM. We evaluated the selectivity of the sensor by testing other oxidizers, such as perchlorate and nitrate, which did not present any electrochemical activity with the molybdate sensing layer.</em></p> <p><em>Additionally, we performed an interferent study with sugar, commonly used as fuel in IEDs, and other common white household powders such as baking soda, flour, and corn starch and neither a false positive nor a false negative result was observed (Chapter 3). As bromate has been reported to have a stronger catalytic effect than chlorate on the redox activity of molybdate, the quantification of bromate was also explored, and a bromate sensor was developed using the findings of the chlorate sensor (Chapter 4). The reaction mechanism involved in the molybdate</em></p> <p><em>reduction was explored and discussed in Chapter 5. The capability of the sensor in detecting chlorate from combusted samples and post-blast samples was successfully demonstrated in Chapter 6, as well as the design of encased prototypes to allow for an in-field presumptive test, storage, and transport for in-laboratory confirmatory tests and compared the performance of the sensor to the available commercial tests.</em></p>

Indiana University-Purdue University Indianapolis (IUPUI) / Canines are regularly utilized by law enforcement agencies to detect explosives. However, the mechanism by which canines respond to explosive vapors is not well understood, leading to difficulties in canine training and testing. It is known that the amount of vapor generated from explosive compounds is dependent upon several factors including sample amount, vapor pressure, and the degree of confinement. Underlying these factors is the basic process of evaporation of an unconfined explosive, which is rucial to understanding how explosive vapors behave in other, more confined, systems. In Stage One of this study, evaporation rates were determined for several explosive liquids using an analytical balance. These rates were compared to one another as well as to theoretical models for the evaporation of liquids. In general and as expected, mass decreased linearly with time and evaporation rates decreased logarithmically as boiling point increased. Several examples of solvent “pinning” on a metal surface were also observed. While an empirical model for the evaporation of unconfined explosive liquids was developed, a comprehensive model for the escape of explosive vapors from sealed containers (i.e., a suitcase, knapsack, or IED container itself) is needed. The second part of Stage One of this study was to determine that the flow rate of explosive vapors escaping from relatively large orifices does not conform to Fick’s Law of Diffusion. Fick’s model states that the flow rate is linearly dependent upon the cross sectional area of the orifice and the material’s diffusion coefficient. Instead, the flow rate was found to be linearly dependent upon the diameter of the orifice due to the tendency of the flow to diffuse outwards from its circular edge. A clear relationship between flow rate and diffusion coefficient was seen, however. Additional uncertainty arises concerning the complexity of the odor generated from explosive compounds. Because explosive vapors are often complex (they consist of multiple chemical compounds), confusion exists regarding the cause of canine alert; that is the “odor compound” that allows for canine detection of various explosives. Although 2, 4- dinitrotoluene (DNT) has been explored as a potential odor compound, the possibility of a nitrated explosive inherently producing nitrated gas upon decomposition has not. Stage Two of this study focused on evaluating nitrate as a potential cause of canine alerts. An LC/MS method for the detection of nitrate ions in Composition C-4 and flake trinitrotoluene (TNT) was developed and tested. Instrumental analysis was not successful in detecting nitrate ions in any of the explosives tested. The lack of nitrate was confirmed using a diphenylamine color test for nitrates, thus eliminating nitrate as an odor compound and cause of canine alert to nitroaromatic compounds. 2, 4-DNT has been introduced as a potential odor compound of TNT, however, the mechanisms behind its vapor emission have not been thoroughly explored. More specifically, due to the “sticky” nature of the 2, 4-DNT isomer, the effects of surface adhesion to container walls are of concern. In particular, whether the amount of material lost to surface adhesion is significant enough to effect canine detection of TNT. A second focus of Stage Two explored this concern. A GC/MS method for the detection and separation of TNT and DNT isomers in liquid extracts was developed and the amount of 2, 4-DNT residues adhering to container walls was quantified. These values, compared to the amount 2,4-DNT expected to saturate each container (determined by the Ideal Gas Law), showed a significant preference of 2,4-DNT in the solid phase as opposed to in the gas phase. The amount of residue adhering to the walls of a gallon can differed from expected values by nearly 70%. The amount of material extracted from a quart can exceeded expected values by 137%. The apparent sticky nature of 2, 4-DNT resulted in a significant loss of material needed to fully saturate a container and thus canine detection success may be affected. In the final stage of this study, theories regarding odor compounds and odor availability of nitromethane, TNT, and Composition C-4 were tested using certified explosives-detecting canines. These trials included thirty-three canine-handler teams from eight government agencies. The odor availability of nitromethane was tested by placing varying volumes of nitromethane in containers with differing degrees of confinement and studying the effects on canine detection success. The odor availability trial showed no significant effect of sample amount or degree of confinement on canine detection so long as the sample volume was sufficient to saturate its container. In this study that volume was determined to be < 1 mL. Detection of 2, 4-DNT, TNT-NESST (Non-Hazardous Explosives for Security Training and Testing), and flake TNT were also studied using certified canines. The purpose of this was to identify the odorant responsible for canine alert to the explosive TNT. These trials showed a significant response to 2, 4-DNT compared to TNT and its training aid; this suggests that 2, 4-DNT is the primary cause of canine alerts to TNT. Additionally, Composition C-4 and RDX-NESTT were tested along with potential odor compounds that included the manufacturing solvent, cyclohexanone, the energetic “taggant” 2, 3-dimethyl-2.3-dinitrobutane (DMNB), the plasticizer dioctyladipate (DOA) and its degradation product 2-ethyl-1-hexanol. While some response to DMNB and cyclohexanone was seen, the most significant response was to the actual Composition C-4. This suggests that the cause of canine alert to Composition C-4 is the explosive mixture as a whole and not a single chemical component of the mixture

<p>  </p> <p>This document is the culmination of four years of research facilitated through the graduate program in the School of Materials Engineering as part of the Purdue Energetics Research center. It includes four manuscripts and one review that were peer-reviewed and published in the journals: <em>Chemistry Open</em>, <em>Organic Letters</em>,<em> RSC Advances</em>, <em>Journal of Inorganic and General Chemistry</em> and <em>Engineering.</em> It also includes work with annulated systems and a new oxidizer for propellants, that will be submitted for publication to peer-reviewed journals in the near future. </p> <p>Discussed here is a brief history of energetic materials as a field, main requirements of energetic materials based on their specific applications, methods of obtaining those requirements, and characterization of energetic materials. Specific topics include: 1,2,3-triazoles as energetic materials, zwitterionic energetic materials, improved synthesis of an energetic material, energetic salts of a fused-ring system, a new oxidizer for propellants, pentazoles, and the future of high-nitrogen energetic materials. </p>