Charlie Oommen

Exceptional activity of mesoporous β-MnO2 in the catalytic thermal sensitization of ammonium perchlorate

Mesoporous β-MnO2 has been prepared, characterized and demonstrated to possess excellent catalytic activity in the thermal decomposition of ammonium perchlorate. The observed unprecedentedly low decomposition temperatures, fast reaction rates and enhanced heat releases in the catalysed formulations make mesoporous β-MnO2 promising as a high-performing ballistic modifier in AP-based composite solid rocket propellants.

Phase Modification of Ammonium Nitrate by Potassium Salts

Modification of the room temperature phase (IV-III) of ammonium nitrate (AN) has been attempted using a variety of potassium salts namely, KF, KCl, KI, KNO3, K2CO3, K2SO4, KSCN and K2Cr2O7. No phase transition was observed when AN containing 1–2% by mass of these potassium salts is heated from room temperature (25°C) onwards in DTA and DSC scans, but the linear expansion due to phase transition was still observable in TMA measurements. Complete arrest of the linear expansion occurs only when a higher concentration of the additive is used. Similarly, in thermal cycling experiments, complete phase modification in the temperature range -80 to 100°C occurs only with a higher percentage of the potassium salt. The extent of modification, however, is found to be dependent both on the concentration, and the type of the anion. Potassium dichromate when used as an additive modifies the phase as well as the decomposition pattern of AN.

Thermal ignition studies on metallized fuel-oxidizer systems

The thermal ignition behaviour of various mixtures of organic fuels, magnesium and ammonium nitrate (AN) has been examined by differential thermal analysis technique. It has been observed that the thermal decomposition/ignition of organic fuel-AN mixtures is modified significantly in the presence of magnesium metal. The decomposition characteristics of the binary mixtures of AN with various metals indicate the specific action of magnesium and zinc in lowering the decomposition temperature. A possible explanation for the low temperature decomposition is given in terms of the solid state reaction causing the fusion of AN which further reacts with the metal resulting in a highly exothermic reaction.ZusammenfassungMittels DTA wurde das thermische Initiierungsverhalten verschiedener Gemische aus organischen Brennstoffen, Magnesium und Ammoniumnitrat (AN) untersucht. Es wurde festgestellt, daß die thermische Zersetzung/Initiierung von Gemischen aus organischen Brennstoffen und AN durch die Gegenwart von metallischem Magnesium bedeutsam beeinflußt wird. Die Zersetzungscharakteristiken binären Gemische aus AN und verschiedener Metalle zeigen eine spezielle Wirkung von Magnesium und Zink bei der Herabsetzung der Zersetzungstemperatur. Eine mögliche Erklärung für die Zersetzung bei niedrigerer Temperatur kann in Bezug auf die Festkörperreaktion gesehen werden, die das Schmelzen von AN verursacht, welches dann mit dem Metall stark exotherm reagiert.РезюмеМетодом дифференциа льного термического анализа изучено тер мическое воспламен ие различных смесей ор ганических топлив, м агния и нитрата аммония (НА). Установлено, что термическое разложе ние/воспламенение с месей органическое топли во — НА значительно меняется в присутст вии металлического магния. Характеристики ра зложения бинарных с месей НА с различными мет аллами показали спе цифическое влияние магния и цин ка в понижении температуры разло жения. Возможное об ъяснение такого низкотемпературно го разложения дано, исходя из твердо тельной реакции прив одящей к плавлению нитрата ам мония, вступающего затем в с ильно экзотермическ ую реакцию с металлом.

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.

Characterization of diglycidylamine epoxy resins based on bis-hydrazones

A series of hydrazones based viscous epoxy resins having N-N bonds in their backbones have been developed as energetic binders for composite solid propellants. A few typical resins have been characterized by their molecular weight distribution,

Thermal stability of hydroxylammonium nitrate (HAN) Role of preparatory routes

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Cerium oxide based active catalyst for hydroxylammonium nitrate (HAN) fueled monopropellant thrusters

NMR spectra and glass transition temperature. The gel permeation chromatography studies carried out show the composition profile in the glycidyl amine synthesis. Spectral studies confirm the epoxidation of the hydrazones. The cured dicarboxyl bishydrazone based resins have glass transition temperatures in the range −13 to

Development of the Multifactorial Computational Models of the Solid Propellants Combustion by Means of Data Science Methods - Phase I

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The Role of Interface Modification on Thermal Degradation and Crystallization Behavior of Composites from Commingled Polypropylene Fiber and Banana Fiber

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Adsorption and decomposition of monopropellant molecule HAN on Pd(100) and Ir(100) surfaces: A DFT study

Among the various non-toxic chemicals being explored as a replacement for hydrazine, hydroxylammonium nitrate (HAN) appears to be most promising and most extensively explored monopropellant for space thrusters. The paper discusses some of the thermal stability issues related to highly concentrated HAN, ensuing from the route adopted for its preparation. It was observed that discharge of metal ions like barium and calcium ions from the reactants and the by-products into HAN solution during preparation could influence the thermal and catalytic decomposition behavior of HAN which is critical for its use in space thrusters. Influence of traces of nitric acid on the thermal decomposition behavior of HAN was also examined.