Preparation, characterization and thermolysis of phenylenediammonium dinitrate salts

Four phenylenediammonium dinitrate salts were prepared and characterized by elemental, Infrared spectroscopy (IR), Ultraviolet spectroscopy (UV) and gravimetric methods. These dinitrates find application in propellant, explosives and pyrotechnics. Their thermal decomposition has been studied using thermogravimetry (TG) and simultaneous thermogravimetry-differential scanning calorimetry (TG–DSC). Kinetics parameters were evaluated by model fitting and isoconversional methods. Their thermolytic pathways have also been suggested, which involves decomposition followed by ignition.     

Synthesis, characterization, thermolysis and performance evaluation studies on alkali metal salts of TABA and NTO

The lithium (Li) and potassium (K) salts of 3-nitro-1,2,4-triazol-5-one (NTO) and 2,4,6-trinitroanilino benzoic acid (TABA) were prepared and characterized during this work. The synthesis was carried out by addition of a solution of lithium/potassium hydroxide to the aqueous solution of NTO and TABA, respectively. The products were characterized by elemental analysis, metal content determination and Fourier Transform Infrared (FTIR) Spectrum. Differential scanning calorimetry (DSC) profile indicated that Li and K salts of NTO and TABA undergo exothermic decomposition in the temperature range of 257-360 degrees C suggesting their energetic nature. The thermo gravimetric (TG) weight loss pattern revealed loss of water for Li/K salts of NTO and TABA in the temperature range of 115-155 degrees C. Sensitivity results revealed that the compounds are insensitive to impact and friction (impact sensitivity--height of 50% explosion>170 cm and friction insensitivity up to 36 kg) stimuli despite even the parent molecule of NTO salts (NTO) being HEM in the hazard category of 1.1. The FTIR spectra of the gaseous products evolved during TGA of NTO and TABA salts indicated the release of NO2. The formation of products such as LiNCO and KNCO was also observed in case of NTO salts, whereas that of CO2 and NH containing products was indicated in case of TABA salts during this study. In order to assess the performance as energetic ballistic modifiers (EBMs), NTO and TABA salts were incorporated in the ammonium perchlorate-hydroxyl terminated polybutadiene (AP-HTPB) composite propellants. The potassium salts enhanced the burning rate of the propellant. The best catalytic effect was obtained with K-TABA salt, which increased the burning rate to the extent of approximately 81% as well as brought down the n-value to 0.15 (pressure 2-9 MPa).     

Synthesis, characterization and thermolysis of 1,1-diamino-2,2-dinitroethylene (FOX-7) and its salts

The present paper discusses the efforts made in HEMRL to establish the synthesis of FOX-7 at 100 g/batch level. In the present study, 1,1-diamino-2,2-dinitroethylene has been synthesised by treatment of acetamidinium chloride with diethylmalonate to obtain 2-methyl-pyrimidine-4,6-dione which on nitration followed by hydrolysis gave FOX-7. The synthesised FOX-7 has been characterized by spectroscopic and thermal techniques. The data obtained confirms the structure of FOX-7. The sensitivity of FOX-7 towards mechanical stimuli indicated its insensitive nature. The theoretically computed explosive and ballistic parameters are close to that of RDX. The synthesised FOX-7 has been used as a precursor for the synthesis of potassium and guanidinium salts and the thermal analysis of these salts indicate their exothermic nature.     

季铵盐改性蒙脱土的制备与表征

采用离子交换法将不同的季铵盐交换到蒙脱土的层间得到改性蒙脱土。以十二烷基二甲基苄基氯(1227)为例,研究了季铵盐离子交换反应的最佳反应条件为:当温度为60℃,时间为6h,1227/CEC的摩尔比为1.5∶1.0时,1227的交换率为82.65%。在相同的条件下,其它的单季铵盐的交换率也均大于80%。其中1431的交换率达到99.75%。热重分析(TG)、X-射线衍射(XRD)、红外光谱(FT-IR)的结果表明季铵盐已经插入蒙脱土的层间,且季铵盐的热稳定性明显提高。     

Preparation,characterization and thermal stability of bentonite modified with bis-imidazolium salts

Sodium bentonite was modified with several organic bis-imidazolium salts. Organoclays with water soluble surfactants were prepared by the traditional cation exchange reaction. The bis-imidazolium-bentonites were characterized by Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction analysis (PXRD) and thermogravimetric analysis (TGA). The effect of chemical composition and molecular weight of the salts on the thermal stability and basal spacing were evaluated. The bis-imidazolium-bentonites showed enhanced thermal stability (300–400 °C) and may be potentially useful materials for melt processing of polymer/layered silicates nanocomposites.     

Preparation,characterization and catalytic behavior of copper oxide nanoparticles on thermal decomposition of ammonium perchlorate particles

In this study, copper oxide nanoparticles (CuO NPs) with mean particle size of 43–32?nm were prepared by wet grinding of commercial micronized CuO powders in a high-energy wet ball-milling apparatus during 20 and 30?h, respectively. X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM) analyses were used to characterize the structure, mean particle size and morphology of the resulting CuO NPs. The results confirmed that the CuO NPs obtained at different milling times consist of nanostructures with nearly spherical morphology and by increasing the milling time, smaller particle size was obtained. The catalytic activities of the synthesized CuO NPs on the thermal decomposition of ammonium perchlorate (AP) particles were examined through differential scanning calorimetry and thermogravimetry (DSC/TG) analyses. Evaluation of the experimental results illustrated that the surfaces of CuO NPs were effectively coated with AP particles and by adding 5%CuO NPs with 32?nm, the thermal decomposition temperature of the treated particles reduced by 83.0°C and the heat of decomposition reached 1553.7?Jg^?1. Moreover, the kinetic and thermodynamic parameters of the thermal decomposition of pure and AP?+?5%CW30 nanocomposites have been investigated by using the Kissinger, Boswell and Ozawa methods.     

Approximate prediction of melting point of nitramines, nitrate esters, nitrate salts and nitroaliphatics energetic compounds

A simple new procedure is introduced to predict melting point of selected class of energetic compounds containing nitramines, nitrate esters, nitrate salts and nitroaliphatics energetic compounds. The number of nitrogen and oxygen as well as the number of nitramine group and the contribution of some specific functional groups would be needed in the new method. Energetic compounds should contain at least one of the functional groups including N-NO(2), C-ONO(2) or nonaromatic C-NO(2). Calculated melting point for 33 nitramines, nitrate esters, nitrate salt and nitroaliphatics are compared with experimental data. Predicted melting points have average deviation of 5.4% for these energetic compounds.     

Synthesis, characterization, thermolysis and performance evaluation of mercuric-5-nitrotetrazole (MNT)

Mercuric-5-nitrotetrazole (MNT) was synthesized on using a reported method. The product having bulk density of 1.5 g/cm3, was obtained during this work using mercuric nitrate doped with additives such as cephol/dextrin in the process. Synthesized MNT was characterized by metal content analysis, IR and ESCA. The DTA profile indicated the thermal stability of MNT up to 200 degrees C. It revealed its higher thermally sensitive [thermal sensitive figure (S) approximately 0.8] in comparison to that of service lead azide (SLA) [S approximately 0.4]. Percussion sensitivity data also showed higher sensitivity of MNT. However, it was found less friction sensitive than SLA. The chemical stability of MNT in a carbon dioxide environment was evaluated in comparison to SLA by determining mercury (gravimetrically) and lead azide (volumetrically) contents respectively. Results obtained indicated that no discernable changes occurred in MNT, even after storage for 90 days while in case of SLA, drastic change in lead azide content was observed. IR spectra of MNT sample stored in a closed aluminum dish for 5-10 years could be superimposed on that of the freshly prepared MNT sample. The performance of MNT filled detonator no. 27 assessed in terms of extent of damage on a witness plate was found equivalent to that of the standard ASA (azide, styphynate and aluminium) composition filled detonator.     

Kinetics of thermolysis of some transition metal nitrate complexes with 1,6-diaminohexane ligand

Metal nitrate complexes of general formula [M(dah)(2)](NO(3))(2) (where M=Zn, Cu and Ni; dah=1,6-diaminohexane) have been prepared and characterized by elemental analysis, infrared spectroscopy (IR) and gravimetric method. The thermal decomposition has been studied using thermogravimetry (TG). Simultaneous thermogravimetry-differential thermogravimetry-differential thermal analysis (TG-DTG-DTA) and differential scanning calorimetry (DSC) were done in N(2) atmosphere. Isothermal TG of initial decomposition of all these complexes, have been carried out to evaluate the kinetics of early thermolysis. Both, model fitting and isoconversional method have been used for the evaluation of the kinetics of thermal decomposition. Model fitting method have given the single value of activation energy (E) whereas, isoconversional method yields a series of E-value, which vary with extent of conversion. Ignition of the complexes was measured to see the response towards rapid heating with varying amounts. The thermal stability of the complexes was found to be in the order as [Zn(dah)(2)](NO(3))(2)>[Cu(dah)(2)](NO(3))(2) approximately [Ni(dah)(2)](NO(3))(2).     

Synthesis, characterization and properties of nitrogen-rich salts of trinitrophloroglucinol

Five different nitrogen-rich salts of trinitrophloroglucinol (H(3)TNPG) have been prepared by the reaction of ammonia, aminoguanidine (AG), carbohydrazide (CHZ), semicarbazide (SCZ) and 5-aminotetrazo (ATZ) with trinitrophloroglucinol in aqueous solution through the heating method of water bath, with the yield up to 80%. These salts were characterized by elemental analysis, FT-IR, DSC and TG-DTG techniques. Their melting temperature is consistent with the thermal decomposition temperature. Their thermal decomposition process and kinetic parameters from 323 to 673K were investigated under a linear heating rate by DSC. The thermal decomposition of these salts undergoes an intensive exothermic decomposition stage to evolve abundant gas products and the enthalpies of exothermic decomposition reaction are high. The tests of sensitivity properties show these salts are insensitivity. All the properties of five nitrogen-rich salts appeared to depend on molecule structures and interconnection. It can be concluded that the five compounds are worthy of further in-depth studies as the gas-generating composition, emission reagents and propellants.     

Inhibition of perchlorate reduction by nitrate in a fixed biofilm reactor

Perchlorate and nitrate were reduced simultaneously in fixed biofilm reactors. Reduction of 1000 microg L(-1) perchlorate decreased slightly with the addition of 10-16 mg L(-1) NO(3)-N when excess acetate was supplied while denitrification was complete. When influent acetate was reduced by 50% to well below the stoichiometric requirement, perchlorate reduction decreased by 70% while denitrification decreased by only 20%, suggesting that competition for electrons by nitrate was a factor in inhibition. Reduction of nitrate was favored over perchlorate, even though reactor biofilm had been enriched under perchlorate-reducing conditions for 10 months. When excess acetate was restored, perchlorate and nitrate returned to initial levels. The average most probable numbers of perchlorate- and nitrate-reducing bacteria during excess substrate operation were not significantly different and ranged between 2.0 x 10(5) and 7.9 x 10(5)cells cm(-2) media surface area. The effect of nitrate on chloride generation by suspensions of perchlorate-reducing populations was studied using a chloride ion probe. The rate of reduction of 2mM perchlorate decreased by 30% in the presence of 2mM nitrate when excess acetate was added. When acetate was limited, perchlorate reduction decreased by 70% in the presence of equi-molar nitrate.     

Preparation of nanostructured materials through thermolysis of metal chelate complexes

We demonstrate that nanocomposites (metals and metal carbides and sulfides) can be produced by thermolysis (370 and 600°C) in a self-generated atmosphere using Cu(II), Co(II), and Ni(II) 2-hydroxy- and 2-N-tosylaminobenzaldehyde azomethine bis-chelates as precursors.     

Energetic co-ordination compounds: synthesis, characterization and thermolysis studies on bis-(5-nitro-2H-tetrazolato-N2)tetraammine cobalt(III) perchlorate (BNCP) and its new transition metal (Ni/Cu/Zn) perchlorate analogues

Bis-(5-nitro-2H-tetrazolato-N²)tetraammine[cobalt(III)/nickel(III)] perchlorates (BNCP/BNNP) and mono-(5-nitro-H-tetrazolato-N)triammine [copper(II)/zinc(II)] perchlorates (MNCuP/MNZnP) have been synthesized during this work. The synthesis was carried out by addition of carbonato tetraammine metal [Co/Ni/Cu/Zn] nitrate [CTCN/CTNN/CTCuN/CTZnN] to the aqueous solution of sodium salt of 5-nitrotetrazole followed by reaction with perchloric acid. The precursors were synthesized by the reaction of aqueous solution of their respective nitrates with ammonium carbonate at 70 °C. The complexes and their precursors were characterized by determining metal and perchlorate content as well as infrared (IR), electron spectra for chemical analysis (ESCA) and X-ray diffraction (XRD) techniques. The TG profiles indicated that BNCP, BNNP and MNCuP are thermally stable up to the temperature of 260–278 °C unlike MNZnP (150 °C). Sudden exothermic decomposition was observed in case of bis-(5-nitro-2H-tetrazolato-N²)tetraammine cobalt(III) perchlorate, bis-(5-nitro-2H-tetrazolato-N²)tetraammine nickel(III) perchlorate and mono-(5-nitro-H-tetrazolato-N)triammine zinc(II) perchlorate resulting in the severe damage of the sample cup. Sensitivity data indicated that the Co/Ni/Cu complexes are more friction sensitive (3–4.8 kg) than mono-(5-nitro-H-tetrazolato-N)triammine zinc(II) perchlorate (14 kg). The impact sensitivity results of the complexes corresponded to h_50% of 30–36 cm.     

Synthesis, characterization, thermal and explosive properties of potassium salts of trinitrophloroglucinol

Three different substituted potassium salts of trinitrophloroglucinol (H(3)TNPG) were prepared and characterized. The salts are all hydrates, and thermogravimetric analysis (TG) and elemental analysis confirmed that these salts contain crystal H2O and that the amount crystal H2O in potassium salts of H3TNPG is 1.0 hydrate for mono-substituted potassium salts of H3TNPG [K(H2TNPG)] and di-substituted potassium salt of H3TNPG [K2(HTNPG)], and 2.0 hydrate for tri-substituted potassium salt of H3TNPG [K3(TNPG)]. Their thermal decomposition mechanisms and kinetic parameters from 50 to 500 degrees C were studied under a linear heating rate by differential scanning calorimetry (DSC). Their thermal decomposition mechanisms undergo dehydration stage and intensive exothermic decomposition stage. FT-IR and TG studies verify that their final residua of decomposition are potassium cyanide or potassium carbonate. According to the onset temperature of the first exothermic decomposition process of dehydrated salts, the order of the thermal stability from low to high is from K(H2TNPG) and K2(HTNPG) to K3(TNPG), which is conform to the results of apparent activation energy calculated by Kissinger's and Ozawa-Doyle's method. Sensitivity test results showed that potassium salts of H3TNPG demonstrated higher sensitivity properties and had greater explosive probabilities.     

Preparation of extrapure potassium nitrate

This paper examines isothermal potassium nitrate crystallization from aqueous solutions and the influence of metallic impurity concentration, percent crystallization, and washing of the crystals on the impurity distribution. We have obtained potassium nitrate with a content of each impurity in the range 5 × 10⁻⁷ to 1 × 10⁻⁵ wt %.     

Preparation and characterization of rice-shaped MnO2/CNTs composite and superior catalytic activity on thermal decomposition of ammonium perchlorate

Manganese dioxides (MnO₂) were successfully deposited on carbon nanotubes (CNTs) surface by redox reaction between potassium permanganate and CNTs. The characterization results showed that the MnO₂ exhibited the rice-shaped nanostructure with about 5～10 nm in width and 10～30 nm in the length on CNTs. The solvothermal temperature of composite can greatly affected its morphology and structure to improve the thermal catalytic on ammonium perchlorate (AP) decomposition. Compared with other samples, the prepared composite at 120°C exhibited superior catalytic performance, as 3wt% of composite added in AP, the second exothermic peak temperature decreased by 160.2°C and the apparent release heat of the thermal decomposition of AP which is four times of that of pure AP. A possible mechanism for formation the rice shaped MnO₂/CNTs composite is also presented.     

Synthesis, characterization and thermolysis studies on triazole and tetrazole based high nitrogen content high energy materials

This paper reports the synthesis, characterisation and thermolysis studies of hydrazinium azotetrazolate (HAZ) and 1,1'-dinitro-3,3'-azo-1,2,4-triazole (N-DNAT). TGA and DSC results suggested that HAZ decomposes in the range of 150-180 degrees C and N-DNAT in the range of 160-170 degrees C, respectively. The pattern of decomposition of HAZ dihydrate and N-DNAT has been predicted with the help of pyrolysis GC/MS technique and a probable decomposition mechanism has been proposed. The theoretically predicted performance data suggests the potential nature of HAZ and N-DNAT for their use in propellant/explosive as well as in gas generator formulations.     

Synthesis, characterization and thermolysis studies on new derivatives of 2,4,5-trinitroimidazoles: potential insensitive high energy materials

This paper reports the synthesis of three new derivatives of 2,4,5-trinitroimidazole namely, 1-methyl-2,4,5-trinitroimidazole (III), 1-carboethoxy-2,4,5-trinitroimidazole (V) and 1-picryl-2,4,5-trinitroimidazole (VII). The title compounds (III) and (V) were synthesized by the nitration of 1-methyl-/1-carboethoxy-(2,4,5-triiodoimidazole) (II and IV) with fuming nitric acid at 0 degrees C and (VII) was synthesized by condensation of 2,4,5-triiodoimidazole (I) with picryl chloride to obtain 1-picryl-2,4,5-triiodoimidazole (VI) followed by its nitration with fuming nitric acid at 0 degrees C. The synthesized compounds have been characterized by elemental analysis, spectral and thermal techniques. The thermolysis studies using TG-DTA revealed exothermic decomposition of the nitroimidazoles (III, V and VII) with T(max) in the temperature range of 196-225 degrees C. The energy of activation obtained for these compounds was in the range 150-170 kJ/mol. The sensitivity data obtained for the newly synthesized compounds (III, V and VII) indicated their safe nature towards external stimuli (h(50%)>100 cm; friction>36 kg) and could be potential candidates for low vulnerable applications in the futuristic systems. The theoretically predicted performance parameters suggest that 1-methyl-2,4,5-trinitroimidazole (III), exhibits higher velocity of detonation (VOD: 8.8 km/s) compared to compounds V and VII (VOD: 7.6 and 8.41 km/s, respectively).     

Preparation,characterization and uses of mullite grain

The properties were compared of grain formed at low temperature from a homogeneous mullite precursor gel, and grain formed from the manufactured material produced at high temperature by fusion or by sintering. A homogeneous precursor gel with the oxide stoichiometry of mullite was prepared by treating technical ethyl silicate with aluminium chlorohydrate, with or without dibutyltin oxide as hydrolysis/gelation catalyst. The gel was dried and heated for 5 h at 700 ° C to remove organic residues then ground to 8 m nominal size to obtain a mullite precursor grain. Crystallites form even at this moderate temperature. Commercially produced fine mullite grain manufactured by fusion or by high temperature sintering was also ground to a give a grain of 8 m nominal size to provide a comparative standard with well known material. Each of the three grain materials, homogeneous precursor gel, fused mullite and sintered mullite, each ground to 8 m nominal size, representative of the fines fraction of a grain mix to be used in producing refractory shapes, was made into compacts which were sintered, and, when cold, tested for compressive and bend strength. Materials of this size were chosen for comparison because of their significance in applications where properties at temperature are important. The precursor gel compacts were 95% crystalline mullite and reached 86% of theoretical density. At 1500 ° C, heated in a 90 deg min^–1 schedule, they had strength comparable to sintered mullite; both materials were much stronger than fused mullite. The results show that sintering procedure has a profound effect on strength, and indicated that in the absence of binder, fused mullite is less reactive than sintered mullite. Some properties of refractory shapes and bricks made from the sintered or fused mullite grain are discussed and some uses in refractory shapes are considered.     

Preparation, characterization, and stability of calcium zinc hydrophosphate

Calcium zinc hydrophosphate phases with different Zn/(Zn + Ca) molar ratios (x_Zn, from 0 to 1) were synthesized using co-precipitation method at pH 10, 25 °C. X-ray diffraction, FT-IR spectroscopy and field emission scanning electron microscopy (FE-SEM) were used to characterize the synthesized products. Thermal behavior of the products was examined by thermal analytical instruments (TG-DSC-MS), while the chemical stability of the products was tested by toxicity characteristic leaching procedure (TCLP).The results showed that the phase constituents of formed calcium zinc hydrophosphate phases were related to the molar contents of Zn²⁺. With the increase of x_Zn, it formed calcium-deficient hydorxyapatite (CaHap), calcium zinc hydorxyapatite (CaZnHap), CaZn₂(PO₄)₂·2H₂O, and Zn₃(PO₄)₂·4H₂O, respectively. All the calcium zinc hydrophosphates were thermally stable up to 600 °C, and less Zn²⁺ leached in a wide pH range of 2-11, which indicated that calcium zinc hydrophosphate could effectively hold Zn²⁺ in their crystal phases with stabilization ratios of over 99.99%.