Phase Stabilized Ammonium Nitrate Research Articles

Thermal behaviour of CuO doped phase-stabilised ammonium nitrate

Copper phase-stabilised ammonium nitrate (Cu-PSAN) was prepared by the incorporation of copper(II) oxide (CuO) into the ammonium nitrate (AN) crystal lattice by a melt process. We studied the phase transitions of ammonium nitrate and dimensional changes occurring during this phase stabilisation process. Crystallographic aspects of the solid-state reaction between AN and CuO and thermal behaviour of phase-stabilised ammonium nitrate (PSAN) are discussed. It was found that solid-state reaction occurred by an intermediate solid solution formation. Lattice parameters and unit cell volume are calculated as a function of temperature from XRD patterns. They show a non-linear and anisotropic behaviour with increasing temperature. Lattice expansion along b-axis and contraction along a- and c-axes are observed. Unit cell volume increases with temperature.

New Propellant Component, Part II. Study of a PSAN/DNAM/HTPB Based Formulation

A study of DNAM as a candidate ingredient for propellant formulations is reported. A formulation including DNAM and based on Phase Stabilized Ammonium Nitrate (PSAN) and Hydroxy-Terminated-Poly Butadiene (HTPB) was selected for the study. This includes thermoanalytical measurements on the mixtures of solid components and propellant samples. Performance is assessed by burning rate measurements. A new small-scale shock sensitivity test developed for studying the propellant under consideration is described. A good potential for DNAM was found for this formulation as revealed by the performance and low vulnerability of the PSAN/DNAM/HTPB composition.

Dynamic XRD Studies of Phase Stabilized Ammonium Nitrate during Temperature Cycling

Dynamic XRD Studies of Phase Stabilized Ammonium Nitrate during Temperature Cycling

Thermal decomposition of solid mixtures of 2-oxy-4,6-dinitramine- s-triazine (DNAM) and phase stabilized ammonium nitrate (PSAN)

The thermal decomposition of solid mixtures of 2-oxy-4,6-dinitramine- s-triazine (DNAM) and phase stabilized ammonium nitrate (PSAN) at different mass ratios has been studied. Simultaneous thermal analysis (DSC/TG) and thermomicroscopy have been used. It was found that PSAN promotes the lowering of the decomposition temperature of DNAM. The beginning of this process occurs when both components are in the solid state irrespective of the composition. However, the composition appears as the main factor determining the process progression once initiated. These observations are interpreted in the light of known properties of both DNAM and PSAN. Non-isothermal kinetic analysis, restricted to the early stage of the decomposition process, has been performed for the particular DNAM/PSAN ratios of 50/50 and 60/40. The complexity of the process is evidenced by the impossibility of being described by a kinetic model function other than an empirical one (Sestak–Berggren). Noticeable differences in the apparent Arrhenius parameters were found, indicating remarkable changes in the process over the composition range of the kinetic analysis.

Phase-Stabilized Ammonium Nitrate-Based Propellants Using Binders with N-N Bonds

Phase-stabilized ammonium nitrate- (PSAN-) based solid propellants have been cast using new epoxy resins having N–N bonds in their structures, as binders. The burning rate studies carried out in a strand burner show that significant enhancement in the burning rate, compared with that observed with conventional polybutadiene binders, could be achieved by the use of the N–N-bonded binders. The PSAN-based propellants have a higher burning rate than those based on ammonium nitrate. The enhancement in burning rate cannot be explained in terms of the calorific value of the resin or the ignition temperature of the propellant. The computed performance parameters of the compositions having N–N-bondedresins as binders are superior to thosebased on polybutadienes. Signi. cantly higher specific impulse and chamber temperature obtained at practical solid loadings appear to be an advantageous feature of the compositions having N–N-bonded resins as binders.

Effect of Energetic Materials on Thermal Decomposition of Phase-Stabilised Ammonium Nitrate - An Eco-Friendly Oxidiser

Phase-stabilised ammonium nitrate (PSAN) was prepared by incorporating copper (II) diamine nitrate in the ammonium nitrate (AN) crystal lattice, thereby avoiding the abrupt volume change within the useful temperature range. The effect of RDX on the thermal decomposition of PSAN has been investigated. Decomposition temperatures of PSAN and RDX are almost in the same temperature range. The synergetic effect of the interaction between PSAN and RDX resulted in a net exothermic reaction of PSAN. The kinetic and thermodynamic parameters of the exothermic decomposition have been computed. Two well-known equations based on variable programme heating rate method, viz., Kissinger and Ozawa equations were employed for the kinetic evaluation. The approximate activation energy obtained from Ozawa method was refined by an iteration procedure using the two-term approximation for Arrhenius temperature integral, p(x) and the refinement was found to be unwarranted for the reaction. There is a close agreement between the values of kinetic parameters of the exothermic reaction of PSAN and RDX obtained from the Kissinger and Ozawa methods.

Study of the decomposition of phase stabilized ammonium nitrate (PSAN) by simultaneous thermal analysis: determination of kinetic parameters

Ammonium nitrate (AN) has been extensively used both in explosive and propellant formulations. Unlike AN, there is a lack of information about the thermal decomposition and related kinetic analysis of phase stabilized ammonium nitrate (PSAN). Simultaneous thermal analysis (DSC-TG) has been used in the thermal characterisation of a specific type of PSAN containing 1.0% of NiO (stabilizing agent) and 0.5% of Petro (anti-caking agent) as additives. Repeated runs covering the nominal heating rates range from 2.5 to 20 K min −1 allowed to conclude on the good reproducibility of the main features of the thermal behavior of PSAN, i.e., two phase transitions, melting and decomposition. Non-isothermal kinetic analysis has been used to estimated the Arrhenius parameters of the decomposition process by applying both a single curve method and two isoconversion methods to the TG data. The results are discussed considering the range of applicability of the methods as well as the influence of the experimental conditions and/or techniques in the kinetic analysis results in a broader sense. A systematic approach based on the isoconversion methods results and statistical tools has been adopted to obtain reliable estimates of the Arrhenius parameters for the thermal decomposition of PSAN. Under the condition of study, the values of 81.4±3.5 kJ mol −1 for the activation energy and (5.63±0.01)×10 5 s −1 for the pre-exponential factor were found as describing the process over a wide range of the kinetic analysis.

A DSC Study on the Effect of RDX and HMX on the Thermal Decomposition of Phase Stabilized Ammonium Nitrate

Phase stabilized ammonium nitrate(PSAN) was prepared by incorporating copper(II) diammine nitrate in the ammonium nitrate(AN) crystal lattice. The effect of two energetic materials viz., RDX and HMX on the thermal decomposition of PSAN was investigated using DSC. The decomposition temperatures of PSAN and RDX are almost in the same temperature range. The decomposition of PSAN is endothermic and that of RDX is exothermic, while that of a 1:1 mixture of the two is exothermic with a net heat release in excess of that of the individual reactions, which is attributed to the combustion reaction among the decomposition products of PSAN and RDX. Though HMX decomposes at a higher temperature, in presence of molten PSAN a substantial portion of it decomposes at a lower temperature along with PSAN with a net excess heat release, again due to the combustion reaction. The kinetic parameters of the two exothermic decompositions were computed using two equations based on variable heating rate method viz., Kissinger and Ozawa equations. The activation energy obtained from Ozawa method was refined by an iteration procedure. There is a close agreement among the values obtained by the three methods. The kinetic parameters for PSAN-HMX mixture are lower, probably due to the effect of its higher heat release.

Preparation of phase stabilized ammonium nitrate(PSAN) by a salting out process.

We describe a method for preparation of PSAN, where the process involves precipitation of ammonium nitrate with potassium nitrate from the aqueous solutions of their salts by the addition of acetone. This kind of process is often referred to as salting out process (Murray and Larson, 1965).

Comparison of the uniaxial tensile modulus and dynamic shear storage modulus of a filled hydroxy-terminated polybutadiene and GAP propellant

The uniaxial tensile moduli for two filled composite solid propellants, one based on a hydroxy-terminated polybutadiene with an ammonium perchlorate oxidizer and the other on a glycidyl azide polymer with a phase-stabilized ammonium nitrate oxidizer, were measured at various temperatures and over a three decade range of strain rates. Dynamic shear moduli were measured at various strains and temperatures over a three decade range of frequencies. Values of the tensile modulus, ET/3 (assuming Poisson's ratio equals 0.5), were compared with the dynamic storage modulus, G′, for each of the dynamic strain levels investigated. The results demonstrate that it is possible to compare 3G′ measured at different dynamic strains and frequencies with the incremental tangent moduli obtained at corresponding uniaxial strains from constant strain rate tests on specimens with a JANNAF geometry. The comparisons are most favourable when the concave-up region of the stress-strain curve extends only up to approximately 2.0% strain. It was observed that G′ obtained at a dynamic shear strain of 2.0% provided the best overall correlation with ET/3 measured over a range of temperatures and strain rates.

Thermal decomposition of phase-stabilised ammonium nitrate (PSAN), hydroxyl-terminated polybutadiene (HTPB) based propellants. The effect of iron(III) oxide burning-rate catalyst

Phase-stabilised ammonium nitrate (PSAN) and hydroxyl-terminated polybutadiene (HTPB) are the main ingredients of propellants used with success in some pyrotechnic igniter components of the VULCAIN liquid rocket engine for the ARIANE 5. Small amounts of selected additives play an important role in solving some of the problems presented by composite propellants that include ammonium nitrate (AN). Iron(III) oxide (Fe 2O 3), for example, can be used as a burning-rate modifier in PSAN/HTPB propellants and although its effect on the burning rate is well known, its mechanism of action is not well understood. Thermogravimetry (TG), differential thermogravimetry (DTG) and differential thermal analysis (DTA) have been applied to study the slow thermal decomposition of selected compositions to investigate the mechanism of action of Fe 2O 3 as a burning-rate modifier of PSAN/HTPB propellants. The compositions evaluated include PSAN, Fe 2O 3 and HTPB cross-linked with isophorone diisocyanate (IPDI) as ingredients. No effect of Fe 2O 3 on PSAN decomposition is found. Fe 2O 3 shows an effect on the kinetics of the first stage of HTPBIPDI decomposition and increases the exothermicity of HTPBIPDI decomposition. In the decomposition of PSAN HTPBIPDI Fe 2O 3 propellants, the effect of Fe 2O 3 is also observed and a synergetic interaction between PSAN and HTPBIPDI is found, for which a physical-chemical explanation is given.

Combustion characteristics of low flame temperature, chlorine-free composite solid propellants

Presently, there is an increased interest in composite solid propellants that burn with low flame temperatures and do not contain chlorine or chlorine compounds. Applications for such propellants may be found in solid propellant gas generators and turbine pump starters. Phase-stabilized ammonium nitrate (ANS)-based propellants meet these requirements, but other composite propellant formulations are also feasible, such as propellants based on a rubber binder and nitroglycerin (NG) or trimethylol-ethane-trinitrate (TMETN). In order to compare the combustion characteristics of these propellants, three different families have been developed and tested: 1) Hydroxy-terminated polybutadiene (HTPB) binder with ANS and various catalysts; 2) Polyester-urethane (PU) binder with NG and nitroguanidine (NQ) or guanidine nitrate (GuNi); and 3) PU binder with TMETN and NQ or GuNi. With some exceptions, all propellant formulations have calculated flame temperatures between 1200 and 1400 K. In a special burner, the combustion characteristics of these propellants have been investigated in the pressure region between 1 and 10 MPa. The results of this study show that burning rates up to 7 mm/s at 10 MPa may be obtained, while the burning rate exponent may vary between 0.3 and 0.7. In addition, the importance of catalysts to improve the ignitability of (ANS)-based propellants is confirmed.