Query: propellant crystallization

title: Mathematical modeling of static layer crystallization for propellant grade hydrogen peroxide
abstract: Hydrogen peroxide (H2O2) is an important raw material widely used in many fields. In this work a mathematical model of heat conduction with a moving boundary was proposed to study the melt crystallization process of hydrogen peroxide which was carried out outside a cylindrical crystallizer. Considering the effects of the temperature of the cooling fluid on the thermal conductivity of crude crystal, the model is an improvement of Guardani's research and can be solved by analytic iteration method. An experiment was designed to measure the thickness of crystal layer with time under different conditions. A series of analysis, including the effects of different refrigerant temperature on crystal growth rate, the effects of different cooling rates on crystal layer growth rate, the effects of crystallization temperature on heat transfer and the model's application scope were conducted based on the comparison between experimental results and simulation results of the model.

title: Numerical investigation of the influence of crystallization of ultrafine particles of aluminum oxide on energy characteristics of solid propellant rocket engine
abstract: The results of numerical investigation of a multiphase flow considering coagulation, crushing and crystallization of the particles of polydispersed condensate in the nozzles of solid propellant rocket engine are presented. The influence of particles crystallization on the energy characteristics of the engine is shown.

title: Lattice Inclusion of Copper Ions in Ammonium Perchlorate through Co crystallization: Impact on Lattice, Physical, and Thermal Characteristics
abstract: Ammonium perchlorate (AP) is an important oxidizer extensively used in composite solid propellants. Any alterations in the lattice configuration of AP could bring in a dramatic change in its physical, thermal, and ballistic characteristics though the basic thermodynamic properties could remain unaltered. In this work, we attempt to dope AP with copper nitrate through co crystallization and examine its impact on the lattice, physical, and thermal characteristics. The effect of copper ion on the crystal morphology, bulk density, friability, moisture content, and the decomposition behavior is compared with normal propellant grade AP. The incorporation of copper ion into AP resulted in an increase in bulk density and aspect ratio and a marginal decrease in the average particle size. The shape factor remained intact. The presence of copper ion remarkably decreased both the low and high temperature decomposition and reduced the activation energy for both stages, confirming the catalytic nature of copper doped AP.

title: Crystallization modelling for lattice modified ammonium perchlorate
abstract: Ammonium perchlorate (AP) is the workhorse oxidizer used in composite solid propellant. The doping of AP with transition metal compounds by physical mixing or cocrystallisation is a method to increase the rate of thermal decomposition of AP. The particle size distribution and crystal characteristics are affected by parameters like initial concentration of solution, agitator rpm, cooling rate, and the concentration of dopants. The exact evaluation of product properties by the systematic study requires a large number of trials by varying each of these parameters. In this paper, factorial method is employed to reduce the number of trials for crystallization of AP and the co crystallisation of AP with different transition metal compounds. Using this method, the optimum condition for obtaining the required particle size distribution and crystal properties can be achieved with minimum number of experimental trials.

title: MODIFICATION OF HIGH ENERGY SUBSTANCES RECOVERED FROM PRODUCTS OF SOLID PROPELLANT DISPOSAL
abstract: The main components of high energy compositions are nitramines: octogen (HMX) hexogen (RDX) The solution to the problem of the lack of these components is possible through the use of returnable resources, which are obtained using a certain technology for the disposal of solid rocket fuel and ammunition, unsuitable for further use for its intended purpose. Purpose of this research is to develop a crystallization method for octogen extracted from solid rocket fuel and to obtain modified nitramine suitable for use in high energy compositions (HEC) Parameters of the process of recrystallization of the extracted nitramine from an aqueous solution of dimethyl sulfoxide (DMSO) were determined in the laboratory: the dependence of the average particle size of the substance on the rotational speed of the mechanical stirrer and the cooling rate of the solution. The required crystal size of the modified nitramine is obtained in the process of crystallization with a rotational speed of a mechanical stirrer in the range of 200 330 rpm and a cooling rate of an aqueous solution of DMSO not higher than 2 degC min, it was found. Addition of seed crystals of standard nitramine up to 10 (by weight) and 0.5 (by weight) modifier (isomethyltetrahydrophthalic anhydride) positively affects the crystalline form of the modified product with the formation of crystals of predominantly correct isometric form. The resulting modified nitramine has characteristics that satisfy the requirements for use in HEC.

title: Catalytic effects of Cu Co* on the thermal decomposition of AN and AN/KDN based green oxidizer and propellant samples
abstract: This paper presents the catalytic effects of Cu Co* catalyst on the decomposition of AN and AN/KDN based oxidizer and propellant samples. Ozawa Flynn Wall (OFW) iso conversional method was used for the kinetic studies and to compute the activation energy (Ea) values for various decomposition steps of the prepared oxidizer and propellant samples in the temperature range of 50 500 degC. TG DTG experiments were carried out for both oxidizer and propellant samples at the heating rates of 3, 5, and 10 degC/min. AN/KDN based oxidizer samples were prepared by an evaporative co crystallization method. Citric acid sol gel method was used for the synthesis of Cu Co* catalyst. The propellant sample contains HTPB as the fuel binder along with other ingredients such as TDI, DOA, and Glycerol. The Cu Co* catalyst was used as 2% by weight to the total weight of catalyzed oxidizer and propellant samples. It was observed from the present study that, Cu Co* catalyst helps in reducing the Ea values for AN and AN based propellant samples. However, with the percentage increment of KDN in the AN crystals, Ea value increases. Further, it was observed that Cu Co* catalyst stabilizes the initial partial decomposition of KDN.

title: Recent Advances in Gun Propellant Development: From Molecules to Materials
abstract: The development of gun propellants from 2010 to 2016 has been a broad endeavor. Researchers worldwide have examined every facet of energetic materials involved with gun propulsion in efforts to improve both safety and performance. They have looked at individual molecules to maximize energy content, as well as revisiting past molecules and improving upon their original properties. A great deal of effort has gone towards understanding and producing energetic nano materials. Co crystallization of energetic materials has also emerged as a promising new methodology to prepare energetics. Processing modifications to the propellant material have shown improvements in burn rate modification. Charge consolidation has seen a resurgence and novel gun concepts have both lead to significant improvements in muzzle velocity at the prototype level. Virtually every aspect of a gun propellant has been examined and improved upon.

title: Effect of crystallization parameters and presence of surfactant on ammonium perchlorate crystal characteristics
abstract: Ammonium perchlorate is an exceptional oxidizer in composite solid rocket propellant formulations. Crystallization is the most critical step in the manufacture of ammonium perchlorate, which determines the size, shape, morphological characteristics, crystal strength, grinding characteristics, and thermal characteristics of the crystals. Attempts are made in the present study to establish the effect of crystallization parameters such as cooling patterns, agitator rpm, retention of crystals in the mother liquor, and presence of surfactant, on the morphological, thermal, and physical characteristics of ammonium perchlorate crystals. Based on the trials conducted in a 5 L capacity laboratory glass crystallizer, it is found that spherical, transparent, and smooth surface crystals are obtained by crystallization having a slow cooling pattern and an agitator rpm of 600. Irregular shaped crystals are obtained under fast cooling pattern and/or lower agitator rpm. It is also seen from XRD patterns that ammonium perchlorate crystals made in the present study do not have any amorphous phase on the surface. Porous nature of the crystals made in the presence of surfactant was verified by scanning electron microscopy images, bulk density, transparency of crystals, and change in the low temperature decomposition pattern in Differential Scanning Calorimeter (DSC) curves.

title: Preparation and Characterization of Fe2O3/Ammonium Perchlorate (AP) Nanocomposites through Ceramic Membrane Anti Solvent Crystallization
abstract: A novel ceramic membrane anti solvent crystallization (CMASC) method was proposed to prepare Fe2O3/AP nanocomposites with core shell structure. For the preparation of Fe2O3/AP nanocomposites, several key advantages of the CMASC method are as follows. Firstly, both well dispersed Fe2O3 nanoparticles and the superfine AP preparation can be achieved at one step. Secondly, no non component of solid propellant was involved in this composite process. Thirdly, the size and morphology of Fe2O3/AP nanocomposites can be effectively controlled by using the ceramic membrane with regular pore structure as feeding template. The morphology and structure of Fe2O3/AP nanocomposites were characterized by inductively coupled plasma spectrophotometry (ICP) IR spectroscopy, SEM, and HRTEM. The results verified that the size and morphology of Fe2O3/AP nanocomposites are controllable, and the dispersion of Fe2O3 nanoparticles is greatly improved in Fe2O3/AP nanocomposites. Moreover, the thermal decomposition of the as prepared Fe2O3/AP nanocomposites was measured with TG DSC. The results showed that the Fe2O3 nanoparticles in Fe2O3/AP nanocomposites exhibit better catalytic activity on the thermal decomposition of AP. In addition, the mechanism was also discussed.

title: Isothermal calorimetry: a predictive tool to model drug propellant interactions in pressurized metered dose systems.
abstract: The purpose of this work was to evaluate gas perfusion isothermal calorimetry (ITC) as a method to characterize the physicochemical changes of active pharmaceutical ingredients (APIs) intended to be formulated in pressurized metered dose inhalers (pMDIs) after exposure to a model propellant. Spray dried samples of beclomethasone dipropionate (BDP) and salbutamol sulphate (SS) were exposed to controlled quantities of 2H,3H decafluoropentane (HPFP) to determine whether ITC could be used as a suitable analytical method for gathering data on the behavioural properties of the powders in real time. The crystallization kinetics of BDP and the physiochemical properties of SS were successfully characterized using ITC and supported by a variety of other analytical techniques. Correlations between real and model propellant systems were also established using hydrofluoroalkane (HFA 227) propellant. In summary, ITC was found to be suitable for gathering data on the crystallization kinetics of BDP and SS. In a wider context, this work will have implications on the use of ITC for stability testing of APIs in HFA based pMDIs.