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[en] The paper is focused on 2,4,6,4',6',2''4''6''-octanitro[l,1',3',1'']terphenyl (ONT), 2,2',2''4,4',4''6,6',6''-nonanitro[l,l',3',1'']terphenyl (NONA), 2,4,6-tris(2,4,6-trinitrophenyl)-1,3,5-triazine (TPT), N,N-bis(2,4-dinitrophenyl)-2,4,6-trinitroaniline (NTFA), 1,3,7,9-tetranitro[l,2,3]benzotriazolo[2,l-a] [l,2,3]benzotriazole-5,11-diium6,12-diide (TACOT-Z), 2,2',4,4',6,6'-hexanitrobiphenyl (HNB), 1,3-dinitrobenzene (1,3-DNB), 1,3,5-trinitrobenzene (TNB) and 2,4,6-triamino-1,3,5-trinitrobenzene (TATB). The initiation reactivity of these substances has been studied by means of the data obtained from non-isothermal differential thermal analysis (DTA), their ignition temperatures, impact sensitivity, the data obtained from the Russian manometric method, the detonation characteristics, DFT B3LYP/6-31G(d,p) charges on the nitrogen atoms of nitro group q N(NO2) and net charges of these groups Q(NO2). For comparison, also the data published and calculated on 2,2',2'',2''',4,4',4'',4''',6,6',6'',6'''-dodecanitro[l,3',1',1''] quaterphenyl (DODECA) have been included. The paper specifies and discusses the relationships between the results of various methods used, inclusive between their outputs and charges and net charges of the primarily reacting nitro groups in the initiations. Relations of these charges to the characteristics of thermal reactivity, detonation and impact sensitivity confirm presumption about the identity of primary chemical processes in the initiation by heat (low-temperature thermolysis), shock and impact. The technologically most attractive substances can be ordered in the sequence TACOT ≥ ONT > TPT > NONA >> NTFA > TATB according to their decreasing thermal stability
[en] We investigate the (002) lattice strain evolution of triaminotrinitrobenzene (TATB) grains inside one TATB-based plastic bonded explosive (PBX) through the in-situ neutron diffraction. By comparing the untreated specimen with the thermal-treated one, it is found that the volume-average response of measured TATB grains remains nearly elastic during quasi-static uniaxial compression. The observed changes in TATB (002) lattice strains correlate tightly with the evolution of damage. A damage parameter defined by the macroscopically determined residual strain is further used to describe the damage degree of PBX, which suggests that the compressive behavior of TATB-based PBX is significantly influenced by the damage evolution. (authors)
[en] As the nation's nuclear weapons age and the demands placed on them change, significant challenges face the nuclear stockpile. Risks include material supply issues, ever-increasing lifecycle costs, and loss of technical expertise across the weapons complex. For example, non-nuclear materials are becoming increasingly difficult to replace because manufacturing methods and formulations have evolved in such a way as to render formerly available materials unprofitable, unsafe, or otherwise obsolete. Subtle formulation changes in available materials that occur without the knowledge of the weapons community for proprietary reasons have frequently affected the long-term performance of materials in the nuclear weapon environment. Significant improvements in performance, lifetime, or production cost can be realized with modern synthesis, modeling, and manufacturing methods. For example, there are currently supply and aging issues associated with the insensitive high explosive formulations LX-17 and PBX 9502 that are based on triaminotrinitrobenzene (TATB) and Kel-F, neither of which are commercially available today. Assuring the reliability of the stockpile through surveillance and regularly scheduled Life Extension Programs is an increasingly expensive endeavor. Transforming our current stockpile surveillance--a system based on destructive testing of increasingly valuable assets--to a system based on embedded sensors has a number of potential advantages that include long-term cost savings, reduced risk associated with asset transportation, state-of-health assessments in the field, and active management of the stockpile.
[en] Vibrational properties of gas-phase TATB molecule and TATB crystal are investigated by means of density functional theory with gradient correction. The intramolecular geometry of TATB crystal agrees reasonably with experiment. The vibrational frequencies of TATB molecule and crystal are computed and the internal modes are analyzed. The simulated infrared spectra of the gas-phase TATB molecule reproduce the experimental spectra fairly well. The structure and vibrational properties of the TATB molecule in gas phase and in crystal phase are compared and discussed in terms of intermolecular interaction
[en] Synchrotron infrared measurements of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) have been performed in the far-IR and mid-IR spectral regions up to ∼30 and ∼40 GPa, respectively. For the far-IR experiment, no pressurizing medium was used, whereas KBr was utilized as a pressurizing medium for the mid-IR experiment. For both experiments, pressure was cycled and IR spectra were recorded at various pressures to ascertain sample survival. In the high frequency region (∼3000 cm-1) of the mid-IR spectra, the peak frequencies of the NH2 symmetric and antisymmetric vibrational modes steadily decrease with increasing pressure, indicating strengthening of intermolecular hydrogen bonding with pressure. In both experiments, no apparent phase transition was observed to the highest pressures studied.
[en] At the 29th International Annual Conference of ICT (1998), the authors described the results of laboratory-scale process development studies for a new synthesis of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). This new synthesis approach-which uses vicarious nucleophilic substitution (VNS) methodology-converts picramide to TATB in high yield, and potentially at lower cost and with few environmental effects than existing synthetic approaches. In this report they describe results of their work on producing TATB by the VNS method at the pilot plant scale. They will discuss structure and control of impurities, changes in yield/quality with reaction conditions, choice of solvents, workup and product isolation, safety, and environmental considerations. Product characterization (particle size, DSC, HPLC, etc.) as well as small-scale safety and performance testing is also discussed
[en] In practical scenarios, cookoff of explosives is a three-dimensional transient phenomenon where the rate limiting reactions may occur either in the condensed or gas phase. The effects of confinement are more dramatic when the rate-limiting reactions occur in the gas phase. Explosives can be self-confined, where the decomposing gases are contained within non-permeable regions of the explosive, or confined by a metal or composite container. In triaminotrinitrobenzene (TATB) based explosives, self-confinement is prevalent in plastic bonded explosives at full density. The time-to-ignition can be delayed by orders of magnitude if the reactive gases leave the confining apparatus. Delays in ignition can also occur when the confining apparatus has excess gas volume or ullage. Understanding the effects of confinement is required to accurately model explosive cookoff at various scales ranging from small laboratory experiments to large real systems.
[en] This paper focuses on destructive fishing practices in coastal Tanzania. I argue that the dominant conservation narrative that increased capacity and ‘political will’ for enforcement of marine protected areas (MPAs) reflects a form of spatial fetishization, in that it overemphasizes the influence of space over social behaviour. I contend that Tanzanian MPAs offer bandage solutions to underlying structural problems that are contingent upon the inconsistent availability of social and financial resources for monitoring activities. I suggest that a paradigm shift is necessary, involving the de-territorialization of marine conservation discourse in Tanzania, and a movement towards addressing the underlying social, political and economic conditions that influence marine resource use.