Effect of trimethylammonium perchlorate on the decomposition and combustion of potassium perchlorate and potassium perchlorate-polyurethane propellants

Addition of trimethylammonium perchlorate to potassium perchlorate (KP) catalyzes its thermal decomposition. However, although the additive sensitises KP-PU propellant decomposition, its combustion is desensitised. The observed effects have been explained in terms of the role played by the early formation of potassium chloride.

Thermogravimetric and mass-spectrometric study of the thermal decomposition of PBCT resins

The thermal decomposition of three commercial samples of carboxy-terminated polybutadiene (PBCT) resins was studied by thermogravimetric analysis (TGA) at heating rates varying from 2° to 100°C/min. Kinetic parameters of the decomposition process at different heating rates were evaluated by means of the Fuoss method.1 The decomposition process and the activation energy values are found to be dependent on heating rate. Mass-spectrometric analysis of the decomposition products shows that the pyrolysis products of PBCT resins are mainly low molecular weight hydrocarbons: ethylene, acetylene, butadiene, propadiene, vinylcyclohexene, etc. The rates of evolution of these hydrocarbon products vary with the carboxy content of the PBCT resin. Based on this, a carbonium ion mechanism has been suggested for the thermal decomposition. The data generated from this work are of importance for a consideration of the mechanism of combustion of composite solid propellants based on PBCT binders.

Synthesis of graphene oxide-intercalated alpha-hydroxides by metathesis and their decomposition to graphene/metal oxide composites

Graphene oxide-intercalated alpha-metal hydroxides were prepared using layers from the delaminated colloidal dispersions of cetyltrimethylammonium-intercalated graphene oxide and dodecylsulfate-intercalated alpha-hydroxide of nickel/cobalt as precursors. The reaction of the two dispersions leads to de-intercalation of the interlayer ions from both the layered solids and the intercalation of the negatively charged graphene oxide sheets between the positively charged layers of the alpha-hydroxide. Thermal decomposition of the intercalated solids yields graphene/nanocrystalline metal oxide composites. Electron microscopy analysis of the composites indicates that the nanoparticles are intercalated between graphene layers. (C) 2010 Elsevier Ltd. All rights reserved.

Kinetics of propellant decomposition

Equations for solid-state decompositions which are controlled by the phase-boundary movement and nucleation have been examined using ammonium perchlorate/polystyrene propellant decomposition at 503 K and 533 K. It was found that 3 different equations governed by the nucleation process show a good fit of data at these temperatures. However, the best fit was obtained for the following Avrami-Erofeev equation, [-In (1 - α]1/4=kt.

Thermal decomposition of zirconyl oxalates I. Barium zirconyl oxalate

Conditions for the preparation of stoichiometric barium zirconyl oxalate heptahydrate (BZO) have been standardized. The thermal decomposition of BZO has been investigated employing TG, DTG and DTA techniques and chemical and gas analysis. The decomposition proceeds through four steps and is not affected much by the surrounding gas atmosphere. Both dehydration and oxalate decomposition take place in two steps. The formation of a transient intermediate containing both oxalate and carbonate groups is inferred. The decomposition of oxalate groups results in a carbonate of composition Ba2Zr2OsCO3, which decomposes between 600 and 800 ~ and yields barium zirconate. Chemical analysis, IR spectra and X-ray powder diffraction data support the identity of the intermediate as a separate entity.

Thermal decomposition of zirconyl oxalates I. Barium zirconyl oxalate

Conditions for the preparation of stoichiometric barium zirconyl oxalate heptahydrate (BZO) have been standardized. The thermal decomposition of BZO has been investigated employing TG, DTG and DTA techniques and chemical and gas analysis. The decomposition proceeds through four steps and is not affected much by the surrounding gas atmosphere. Both dehydration and oxalate decomposition take place in two steps. The formation of a transient intermediate containing both oxalate and carbonate groups is inferred. The decomposition of oxalate groups results in a carbonate of composition Ba2Zr2O5CO3, which decomposes between 600 and 800° and yields barium zirconate. Chemical analysis, IR spectra and X-ray powder diffraction data support the identity of the intermediate as a separate entity.Die Bedingungen für die Herstellung von stöchiometrischem Barium-zirconyl-oxalat Heptahydrat (BZO) wurden standardisiert. Die thermische Zersetzung von BZO wurde unter Einsatz der TG-, DTG- und DTA, sowie der chemischen und Gasanalyse untersucht. Die Zersetzung verläuft über vier Stufen und wird von der umgebenden Gasathmosphäre nicht besonders beeinflusst. Sowohl die Dehydratisierung als auch die Oxalatzersetzung erfolgt in zwei Stufen. Die Bildung einer intermediären Übergangsverbindung mit sowohl Oxalat- als auch Carbonatgruppen wirken hierbei mit. Die Zersetzung der Oxalatgruppen ergibt ein Carbonat der Zusammensetzung Ba2Zr2O5CO3, das zwischen 600 und 800° zersetzt wird und Bariumzirconat ergibt. Die Angaben der chemischen Analyse, der IR-Spekren und der Röntgen-Pulver-Diffraktion unterstützen die Identität der Intermediärverbindung als eine separate Einheit.On a standardisé les conditions de préparation de l'oxalate heptahydraté de zirconyle et de baryum (BZO) stoechiométrique. On a étudié la décomposition thermique de BZO par TG, TGD et ATD ainsi que par analyses chimiques et analyses des gaz. La décomposition a lieu en quatre étapes et n'est pas trop influencée par l'atmosphère ambiante. La déshydratation et la décomposition de l'oxalate ont lieu en deux étapes. Il se forme un composé intermédiaire de transition contenant à la fois les groupes oxalate et carbonate. La décomposition des groupes oxalate fournit un carbonate de composition Ba2Zr2O5CO3 qui se décompose entre 600 et 800° pour fournir du zirconate de baryum. L'analyse chimique, les spectres IR et la diffraction des rayons X sur poudre, apportent les preuves de l'existence d'un composé intermédiaire comme entité séparée.

Thermal decomposition of ethylene diamine diperchlorate

Thermal decomposition of ethylene diamine diperchlorate (EDDP) has been studied by differential-thermal analysis (DTA), thermogravimetric analysis (TGA), isothermal weight-loss measurements and mass-spectrometric analysis of the decomposition products. It has been observed that EDDP decomposes in two temperature regions. The low-temperature decomposition stops at about 35 to 40 percent weight loss below 250°C. The reason for the low-temperature cessation may be the adsorption of excess ethylene diamine on the crystal surface of EDDP. An overall activation energy of 54 kcal per mole has been calculated for the thermal decomposition of EDDP. Mass-spectrometric analysis shows that the decomposition products are mainly CO2, H2O, HCl and N2. The following stoichiometry has been proposed for the thermal decomposition of EDDP: (−CH2NH3CIO4)2→2CO2O+2HCl+N2

Inherent structures of phase-separating binary mixtures: Nucleation, spinodal decomposition, and pattern formation

An energy landscape view of phase separation and nonideality in binary mixtures is developed by exploring their potential energy landscape (PEL) as functions of temperature and composition. We employ molecular dynamics simulations to study a model that promotes structure breaking in the solute-solvent parent binary liquid, at low temperatures. The PEL of the system captures the potential energy distribution of the inherent structures (IS) of the system and is obtained by removing the kinetic energy (including that of intermolecular vibrations). The broader distribution of the inherent structure energy for structure breaking liquid than that of the structure making liquid demonstrates the larger role of entropy in stabilizing the parent liquid of the structure breaking type of binary mixtures. At high temperature, although the parent structure of the structure breaking binary mixture is homogenous, the corresponding inherent structure is found to be always phase separated, with a density pattern that exhibits marked correlation with the energy of its inherent structure. Over a broad range of intermediate inherent structure energy, bicontinuous phase separation prevails with interpenetrating stripes as signatures of spinodal decomposition. At low inherent structure energy, the structure is largely phase separated with one interface where as at high inherent structure energy we find nucleation type growth. Interestingly, at low temperature, the average inherent structure energy (< EIS >) exhibits a drop with temperature which signals the onset of crystallization in one of the phases while the other remains in the liquid state. The nonideal composition dependence of viscosity is anticorrelated with average inherent structure energy.

Insertion of nickel nanoparticles in the interlayers of alpha-zirconium phosphate by the decomposition of the intercalated nickel acetate

By employing EXAFS and magnetic measurements, it is shown that nanoparticles of nickel along with those of NiO are incorporated between the layers of a-zirconium phosphate (ZrP) by the thermal decomposition of nickel acetate intercalated in ZrP. The nickel nanoparticles are superparamagnetic. Hydrogen reduction produces small ferromagnetic nickel particles, most of which appear to be outside the interlayer space of ZrP.