Showing papers in "Journal of Energetic Materials in 2000"

Preparation and explosive properties of azo- and azoxy-furazans

Abstract: The synthesis and properties of three energetic azo- and azoxyfurazans are described. All are derived from oxidation of 3, 4-diaminofurazan (DAF) (1) and include 3,3′-diamino-4,4′-azoxyfurazan (DAAF) (2), 3,3′-diamino-4,4′-azofurazan (DAAzF) (3) and bis[1, 2, 5] oxadiazolo [3,4-c:3′,4′-g] [1, 2, 5, 6] tetrazocine (DFT) (4). The explosive performance properties of DAAF and DAAzF have been investigated.

The properties of ammonium dinitramide (ADN): Part 1, basic properties and spectroscopic data

Abstract: Basic properties and spectroscopic data for the energetic oxidizer ADN (Ammonium dinitramide (NH4N(NO2)2)) are presented. The ADN used for this work was synthesized by a new efficient and environmentally friendly method. The method is based on a direct nitration of salts of sulfamic acid by ordinary mixed acid, followed by neutralization and separation of the ADN by the use of an adsorption column. The heat of formation was measured by burning in hydrogen atmosphere in an adiabatic bomb calorimeter and was found to be 148 kJ/mole ±10 kJ/mole. The melting point was determined using DSC technique and is 93.5°C. This paper reports drop weight, friction and bullet impact sensitivity data. The friction sensitivity of ADN is much lower than that of RDX. The impact sensitivity of ADN is of the same magnitude as that of RDX but varies a great deal with the morphology of the particles, e. g. prilled ADN is nearly twice as insensitive as RDX. The bulk density measured by powder X-ray diffraction and was fo...

Fatigue of lx-14 and lx-19 plastic bonded explosives

Abstract: The DOD uses the plastic bonded explosive (PBX) LX-14 in a wide variety of applications including shaped charges and explosively formed projectiles.1 LX-19 is a higher energy explosive, which could be easily substituted for LX-14 because it contains the identical Estane 5703p binder and more energetic CL-20 explosive. Delivery systems for large shaped charges, such as TOE 2, include the Apache helicopter. Loads associated with vibrations and expansion from thermal excursions in field operations may, even at low levels over long time periods, cause flaws, already present in the PBX to grow. Flaws near the explosive/liner interface of a shaped charge result in reduced performance. Small flaws in explosives are one mechanism (the hot spot mechanism) proposed for initiation and growth to detonation of PBXs like LX-14, PBXN 5, LX-04 and LX-17 among others. Unlike cast-cured explosives and propellants, PBXs cannot usually be compression molded to full density. Generally, the amount of explosive ignited...

Gas production from thermal decomposition of explosives: Assessing the thermal stabilities of energetic materials from gas production data

Abstract: The gas formation associated with the thermal decompositions of nineteen energetic materials was determined at three temperatures (120°C, 220°C and 320°C). Although there was considerable variability within classes, among the largest producers of gas were the nitrate esters. PETN (pentaerythritol nitrate) generated about 6.3mole gas per mole, while nitrocellulose, produced almost no gas. Second in gas production were the nitramines, followed by nitroarenes and lastly, energetic salts. NTO (5-nitro-2, 4-dihydro-3H-1, 2, 4-triazol-3-one), which does not fit into the four main classes of energetic materials, exhibited gas production (2.13 mole gas per mole NTO) comparable with some nitroarenes and the energetic salt, ammonium dinitramide (ADN). For selected compounds gas evolution data was used to construct first-order plots, from which Arrhenius parameters were determined and compared with previously reported values.

Synthesis and characterization of 2,4,6-tris (3′, 5′-diamino-2′,4′,6′-trinitrophenylamino)-1,3,5-triazine (PL-1): A new thermally stable insensitive high explosive

Abstract: 2,4,6-tris (3′,5′-diamino-2′,4′,6′-trinitrophenylamino)-1,3,5-triazine (PL-1). has been synthesized in 29—31% overall yield from cyanuric chloride and 3,5-dichloroaniline following condensation, nitration and amination reactions. The structure of the compound has been assigned on the basis of spectral data (IR, 1H-NMR and Mass) and elemental analysis. Some of the physico-chemical and explosive properties including thermal behaviour of the compound are also reported.

Base hydrolysis of TNT-Based explosives

Abstract: Four TNT explosive formulations were treated with 1.5 M and 3 M solutions of sodium hydroxide (NaOH) at temperatures between 90°C and 150°C. The reaction time needed for over 99% conversion of the explosive compound was less than 5 minutes at 150°C for both Octol and Comp B, and less than 30 minutes at 90°C for Tritonal and Tetrytol. The TNT and Tetryl fractions of the explosive produced negligible gas and liquid products were ammonia, sodium acetate, sodium formate, and sodium nitrite. The RDX and HMX fractions produced a substantial amount of gas and the major products were nitrous oxide, nitrogen, and ammonia. The aluminum used in Tritonal was converted to aluminum hydroxide and hydrogen gas.

Influence of 1,4-dinitropiperazine (DNP) on the pressure index of rdx containing extruded double base propellants

Abstract: Effect of 1,4-dinitropiperazine (DNP) in bringing down the pressure index (n) in RDX - containing extruded double base propellents has been studied. Experiments have been conducted on two sets of formulations based on controls of low calorimetric value (870 cal/g) and high calorimetric value (1070 cal/g). RDX content was varied between 10 and 20% and DNP content from 2 to 6 parts per 100 parts of the base composition. DNP alone does not bring down n appreciably; however, in conjuction with Basic Lead Salicylate, a well known ballistic modifier (2 parts), it brings down the n in the 70–105 kg/cm2 pressure range significantly. The effect is more pronounced in the low calorimetric value compositions and a plateau effect has been observed. Addition of dinitropiperazine does not adversely affect the thermal and chemical stability of the formulations nor their mechanical properties. The temperature sensitivity of burn rate of DNP containing formulations was reduced to 0.21% / °C as compared to that of ...

Study of the thermal initiation of ammonium dinitramide (ADN) crystals and prills

Abstract: The thermal initiation by electron beam heating (and calibrated hot stage), of single crystals and prills of ADN, has been filmed / recorded in an Environmental Scanning Electron Microscope, from the formation of microscopic “reaction sites” (0.01 μm in diameter) to full crystal consumption. The transformations of the ADN prills and crystals were compared and recorded in real time at various magnifications (x10,000-100) and under different atmospheres (pure nitrogen and nitrogen/water vapour mixtures). The initiation characteristics of the prills and crystals were found to differ and are related to the microstructural characteristics produced by different prill manufacturing techniques namely, the “prilling tower” technique (Thiokol) and the “melt-stir” technique (CSD).

Studies on metal salts of 4-(2,4,6 - trinitroanilino) benzoic acid

Abstract: Synthesis, characterization and thermal studies of copper and lead salts of 4-(2,4,6-trinitroanilino) benzoic acid have been carried out. Differential thermal analysis data show that Pb2+ and Cu2+ salts are stable up to 240 and 260°C respectively and then decompose exothermically. Impact sensitivity value (h50) is 77 cm for lead salt and 170 cm for copper salt. Both the salts are found friction insensitive upto 36 kg. The calorimetric values of lead and copper salts are 679 and 839 cal/g, respectively.

Factors that affect the impact sensitiveness of ammonium nitrate - fuel oil (ANFO) explosives containing aluminium

Abstract: We report the results of a study to investigate the effect of aluminium on the impact sensitiveness of a range of Ammonium Nitrate-Fuel Oil (ANFO) mixtures. The data obtained indicate that the impact sensitiveness of these mixtures depends on the quantity and type of aluminium, and on the ratio of ammonium nitrate to fuel oil. The magnitude of the dependences is relatively small, however, and all the aluminium-ANFO mixtures examined can be classed as “comparatively insensitive”. We have also shown that the sensitiveness of such mixtures to impact can increase if they contain small quantities of rust or grit as a contaminant.

Combustion mechanism of the low signature propellant containing 1,7-diazido-2,4,6-trinitrazaheptane(dath)

Abstract: The thermal decomposition behavior of the low signature (LS) propellant containing 1,7-diazido-2,4,6-trinitrazaheptane(DATH) is investigated by DSC, TG and DTG technique. Several analysis methods are used to study the physico-chemical structure of surface before and after combustion and the burning flame structure of this kind of propellant. Because DATH decomposes to produce a great quantity of N2, the physico-chemical structure of burning surface of the propellant is obviously different from that of RDX-CMDB (Composite Modified Double-Base) propellant. It's mainly N2, that gives rise to forming a lot of pores on the burning surface for its release. These pores can increase the burning rate because of extending the burning surface and increasing thermal-transfer intensity. In comparison with decomposition and combustion process of RDX-CMDB propellant, the propellant containing DATH creates the different decomposition products from the condensed phase to the fizz zone.

Synthesis and characterization of some new acid salts of 8H-2,6,8,9,10-Pentaazabicyclo[5,2,1]-deca-2,5,9,10-tetraene

Abstract: Some new acid salts of 8H-2,6,8,9,10-pentaazabicyclo[5,2,1]-deca-2,5,9,10-tetraene were prepared and characterised by spectral data (IR, 1H-NMR and Mass) and elemental analysis. The purity of these compounds was confirmed by HPLC and was found to be > 95% pure. In addition, the compounds were subjected to impact and friction sensitivity tests and were found very safe.

Modified vacuum thermal stability test apparatus for energetic materials

Abstract: An apparatus, hereinafter named the modified vacuum thermal stability (MVTS) test apparatus, that replaces the mercury manometric method used to determine the vacuum thermal stability of energetic materials is described. The volume calibrated MVTS system provides continuous pressure/time data for the duration of the test via a computerized data acquisition system. Total gas volume (reduced to STP) is computed from the pressure data. Subsequent gas chromatographic analysis of the evolved gaseous mixture further provides identification and individual volumes of the components. Water/solvent volume is obtained by difference (Vp — VCalibrated Gases GC).

A new closed vessel for determining the ballistic performance of high energy solid and liquid gun propellants

Abstract: A new closed vessel, designed and build by Cranfield University under contract to the UK Defence Evaluation and Research Agency (DERA), is described. The jacketed vessel, which can be operated at high pressure (500 MPa) and has the capability of firing liquid monopropellants, is fitted with a single instrumented head and a detachable liner. The internal surface profile of the combustion chamber is shaped so as to prevent the build up of shock waves which can occur between parallel surfaces and this feature leads to improved output signal quality. Vessel venting following a firing is carried out by remote control via a proprietary air-actuated high pressure valve. The vessel can be fitted with optical windows or converted to a vented device for gas erosion studies.

Lead salt of 2, 4, n-trinitroanilinoacetic acid - an energetic ballistic modifier for double base propellants

Abstract: Lead Salt of 2,4,N-trinitroanilinoacetic acid has been evaluated as ballistic modifier in composite modified double base matrix. Burn rate measurements showed a plateau effect between 3.43 — 8.82 MPa. The salt-containing propellant composition showed a synergistic effect on decomposition of propellants as evidenced by a reduction in differential thermal analysis exotherm peak temperature. Effect of magnesium oxide-lead salt combination on burn rate of propellant formulation was also evaluated. The combination increased the burn rate at 6.86 — 8.82 MPa and decreased at 10.78 MPa. The salt has been prepared by double decomposition of lead nitrate with sodium salt of 2,4,N-trinitroanilinoacetic acid, which in turn is prepared from glycine and 2,4 - dinitrochlorobenzene. The lead salt decomposes at 187°C as shown by differential thermal analysis exotherm. Calorimetric value (+3.14 MJ/kg) of the salt has been calculated. The salt exhibits an impact sensitivity height (h50) of 97.5 cm and friction sens...

Two potential energetic compounds: Ammonium superoxide and ammonium ozonide

Abstract: Two proposed ionic compounds, NH4O2 and NH4O3, are discussed in terms of several properties related to energetic performance. These include oxygen content, moles of gas produced and heat released upon decomposition, and specific impulse. The heat release was calculated in each instance using the predicted lattice energy, which was obtained from the computed electrostatic potential on the surface of the negative ion. NH4O2 is found to be superior to HMX in each property considered, while NH4O3 is better than HMX in some and comparable in the others.