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1

Mechanical and Sensitivity Properties of Cast PBXs Containing Agglomerated TATB

Cai Jialin, Luo Guan, Huang Hui, Zhen Shensheng, Shi Yuantong

Central European Journal of Energetic Materials

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2022

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Vol. 19, no. 2

168--180

EN

The aim of this study was to investigate the effects of agglomerated TATB on the mechanical and sensitivity properties of cast polymer-bonded explosives (PBXs). By introducing agglomerated TATB, cast PBXs with a high solids content can be obtained. The mechanical properties of TATB-based cast PBXs were evaluated by tensile and compression tests. The experimental results showed that the addition of the agglomerated TATB clearly enhanced the ductility and fracture toughness, but decreased the strength of the PBXs. However, the strength increased with the decreasing particle size of the agglomerated TATB. When TATB-crystal was replaced by agglomerated TATB in the cast PBXs, a significant drop in the initial modulus and stress were observed. Samples with a higher content of agglomerated TATB were less sensitive to impact stimuli. The desired mechanical and sensitivity characteristics may be achieved for TATB-based cast PBXs by introducing agglomerated TATB.

2

Effect of the Molecular Structure and Molecular Weight of Poly(Vinylidene Fluoride-Chlorotrifluoroethylene) Copolymers on the Characteristic Properties of TATB-based Composites

Singh Arjun, Sharma Tirupati Chander, Kumar Mahesh

Central European Journal of Energetic Materials

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2020

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Vol. 17, no. 3

428--450

EN

1,3,5-Triamino-2,4,6-trinitrobenzene (TATB) based composites with different molecular weights and molecular structures of poly(vinylidene fluoride-chlorotrifluoroethylene) (poly(VDF-CTFE) binder were studied to investigate their effect on the physical, thermal, mechanical and explosive properties. The poly(VDF-CTFE) with three different kinds of molecular weights (FKM1, FKM2 and FKM3 samples) and three different kinds of molar ratios of VDF and CTFE (FKM4, FKM5and FKM6) was chosen as the polymeric binder. The experimental results indicated that all of these kinds of TATB-based composites do not show any measurable changes in the particle density, detonation velocity and impact sensitivity. The thermal data revealed that weight loss occurs in two steps and, that the thermal stability deceases slightly with an increase in the molecular weight. On other hand, the weight loss occurred in a single step and the thermal stability increases slightly with an increase in the molar ratio of the CTFE to VDF monomer units. The adhesion properties between the two phases of TATB crystals and polymeric matrices rely on the properties of the interface, which is expressed in terms of the mechanical properties. The storage modulus decreases with increasing molecular weight. On other hand, an increase in the CTFE to VDF molar ratio in the poly(VDF-CTFE) binder remarkably improves the mechanical strength. FKM5-9505 shows a significant reduction in creep deformation and dramatically increases the elongation failure, compared to those of the FKM4-9505 sample. Finally, SEM observations clearly suggested that the coating of the polymer matrix onto the surface of the TATB crystals is clearly demonstrated.

3

Preparation and Characterization of Ultrafine HMX/TATB Explosive Co-crystals

An C., Li H., Zhang Y., Ye B., Xu C., Wang J.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 4

876--887

EN

An explosive co-crystal of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) was prepared by the ball milling method. The raw materials and co-crystals were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and Raman spectroscopy. Impact and friction sensitivity of the co-crystals were tested and analyzed. The results showed that the HMX/TATB co-crystals are spherical in shape and 100-300 nm in size. The co-crystals are different from anintimate mixture of HMX/TATB and they exhibit a new co-crystal structure. HMX/TATB co-crystals are formed by N-O···H hydrogen bonding between −NO2 (HMX) and −NH2 (TATB). The drop height of ultrafine HMX/TATB explosive co-crystals is 12.7 cm higher than that of ultrafine HMX, whilst the explosion probability of friction is 20% lower than that of ultrafine HMX. Ultrafine HMX/TATB explosive co-crystals are difficult to initiate under impact and friction conditions.

4

Mild Method to Synthesize TATB by Amination of 1,3,5-Trialkoxy-2,4,6-Trinitrobenzene under Phase Transfer Catalysis Conditions

Chang T., Li B., Chen L., Ge L., Lu M.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 1

47--59

EN

Nucleophilic amination, as a vital step in the synthesis of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) using 1,3,5-trialkoxy-2,4,6-trinitrobenzene (TORTNB) and aqueous ammonia as the starting materials and catalyzed by phase transfer catalysis (PTCs) under mild conditions is described. Various phase transfer catalysts, such as crown ethers, tertiary amines, quaternary ammonium salts, poly ethers and cyclodextrin, and various experimental parameters, such as no. of equivalents of PTC, mole ratio of ammonium hydroxide to the starting material, reaction time, reaction temperature and cycle times of the organic phase were investigated. The crown ethers, especially 18-crown-6, show good catalytic activity and re-usability for the amination of 1,3,5-triethoxy-2,4,6-trinitrobenzene giving a yield of 96.52%. This makes for a safe process and suitable for scale-up, because the reactions are carried out under atmospheric conditions. The material synthesised by the new system was characterized by DSC, SEM and LPS.

5

A Validated Reverse Phase HPLC Technique for the Determination of TATB Assay

Bhattacharyya S. C., Patil R. S., Santosh M. S. S. N. M., Bhattacharya B., Malik R. K., Mehra A.

Central European Journal of Energetic Materials

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2016

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Vol. 13, no. 3

641--657

EN

The main hurdle for the estimation of the purity of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) is its insolubility in most of the known organic solvents. In the conventional method, TATB is digested with steam in a modified Kjeldahl digester and the ammonia evolved is estimated quantitatively. To do away with this cumbersome method, a simple, rapid HPLC technique using a reverse phase C-18 column has been established for quantitative determination of the purity of TATB. A sharp and symmetrical peak with a retention time of 2.92 min at 355 nm is obtained for pure TATB when the flow rate is 2.0 mL/min. The linearity of the detector response has been studied with sample concentrations ranging from 10 to 50 mg/L. The method addresses two important issues of sample preparation and the precision of measurement. Unlike the previously reported HPLC techniques which mainly aimed at the detection of TATB, the present work is a validated account of a quantitative estimation of purity. Regular production batch samples have been assayed by this method and the results are compared with those obtained from the conventional analysis. The HPLC method is convenient and reliable for quality control of the product at the plant level.

6

Process Optimization for the Gas-Liquid Heterogeneous Reactive Crystallization Process Involved in the Preparation of the Insensitive High Explosive TATB

Nandi A. K., Kshirsagar A. S., Thanigaivelan U., Bhattacharyya S. C., Mandal A. K., Pandey R. K., Bhattacharya B.

Central European Journal of Energetic Materials

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2014

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Vol. 11, no. 1

31--57

EN

The thermally stable, insensitive, high explosive 1,3,5-triamino-2,4,6- trinitrobenzene (TATB) is manufactured by amination of 1,3,5-trichloro-2,4,6- trinitrobenzene (TCTNB) in toluene with NH3 gas. It is an isothermal, single-feed, semi-batch, gas-liquid heterogeneous, reaction crystallization process. The amination process is discussed by applying the chemical engineering methodology of mass transfer and reactive crystallization processes based on Two-Film Mass- Transfer (TFMT) theory. Kinetic expressions have been developed to define the chemical reactions as well as the physical phenomena (mass transfer) associated with this process. A single expression has been derived to explain the dependence of the ammonia consumption rate on various process parameters. Subsequently, the influence of various process parameters on the product quality (particle size and chloride impurity content) has been studied on the laboratory scale. Finally, the process has been established in the pilot plant, with optimized process conditions, to realize TATB of desired particle size and chloride content. The effects of feeding excess ammonia, and the presence of mercaptans/hydrogen sulphide impurities in poor quality toluene on the formation of certain undesirable by-products in TATB, are also discussed.

7

Studies on High Burning Rate Composite Propellant Formulations using TATB as Pressure Index Suppressant

Mehilal, Jawalkar S., Kurva R., Sundaramoorthy N., Dombe G., Singh P. P., Bhattacharya B.

Central European Journal of Energetic Materials

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2012

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Vol. 9, nr 3

237-249

EN

High burning rate propellant compositions are generally used in gas generators to eject missile from canister. Because of high burning rate, pressure index of the composition increases during burning. To reduce the pressure index, a high burning rate composite propellant formulations (~20 mm/s) based on AP/HTPB/Al have been prepared by incorporating TATB and studied in detail for viscosity build-up, thermal and mechanical properties, sensitivity as well as burning rate and pressure index (n). The data indicate that there is a decrease in end of mix viscosity on increasing the percentage of TATB. The same trend was also observed with mechanical properties while significant improvement in overall thermal stability was clearly observed. The sensitivity data indicate that impact and friction values show decreasing trend infer better safe to handle. The burn rate data reveal that on addition of TATB from 0.5 to 2% decrease in burning rate was not observed while on addition of further TATB up to 5% and beyond this significant decrease in burning rate was observed. The data on pressure index (n) also reveal that TATB is very effective in reducing the 'n' value up to 2% and beyond this 'n' value increases close to standard composition. The data on 'n' value reveal that it reduces from 0.47 to that of standard composition to 0.36 for the compositions containing TATB up to 2.0% in the pressure range of 60-90 kg/cm2.

8

Investigation on Irreversible Expansion of 1,3,5-Triamino-2,4,6-trinitrobenzene Cylinder

Sun J., Kang B., Zhang H., Liu Y., Xia Y., Yao Y., Liu X.

Central European Journal of Energetic Materials

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2011

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Vol. 8, nr 1

69-79

EN

In this study, the irreversible expansion of TATB cylinder is investigated. No evident variation of the lattice parameters is observed on TATB crystal. The density of TATB powder decreases by only about 0.02% after it suffered from thermal cycling process at the range from -54 C to 74 C, while the density of TATB cylinder decreases by about 1.0%. It is suggested that the density variation of TATB powder has little contribution to the density decrease of TATB cylinder. Therefore, the increasing interstices between TATB powder originated from the thermal cycling should be responsible to the irreversible expansion of TATB cylinder.