Burning Rate Modifier Research Articles

Burning Rate Studies: Potassium-Doped Ammonium Perchlorate with Other Burn-Rate Modifiers

Iron oxide and copper chromite have been used as burn-rate modifiers of composite solid propellants. In recent times, studies have been reported on potassium-doped ammonium perchlorate and on dry activated charcoal. These have shown an increase in composite solid propellant burning rates. The studies on composite solid propellants using dry activated charcoal have also shown a reduction in the burn-rate pressure index for a composite solid propellant. With this knowledge, experiments are conducted to develop compositions that result in both high burning rates and low burn-rate pressure index of the propellant. In addition to these, the study also reports propellants with dual burn-rate pressure index. The change in the burn-rate pressure index is from 0.2 to 0.65 in one of the propellants. These could be very useful in that the same grain can act as boost and sustain grain depending on the combustion chamber pressure. With the addition of different burn-rate modifiers, the pressure at which the change in burn-rate pressure index is observed shifts. This could be a very useful tool for propellant designers. It was observed that, with the use of activated charcoal along with potassium-doped ammonium perchlorate, the burn-rate pressure index was brought down from around 0.65 to 0.38, whereas the burn rates were still higher (60%) than the base propellant.

Use of Magnesium Diboride as a “Green” Fuel for Green Illuminants

We report here on the use of magnesium diboride (MgB2) as a barium-free alternative for the pyrotechnic generation of green light. Formulations employing KNO3 as the oxidizer, MgB2 as the fuel, and various binders and additives were investigated. Upon combustion, the compositions were found to generate the photochemically active BO2 radical, which emits green light. Fixing the MgB2 content at 21 wt % gave the closest dominant wavelength (561.4 nm) to that desired for green illuminants and a spectral purity of 33%. The addition of burning rate modifiers to this system was found to inhibit the formation of the BO2 radical. Exchanging the KNO3 oxidizer for NH4ClO4 increased the spectral purity to 45%. Correlations between the results of thermodynamic modeling and the experimental data are also reported.

Cu–Co–O nano-catalysts as a burn rate modifier for composite solid propellants

Abstract Nano-catalysts containing copper–cobalt oxides (Cu–Co–O) have been synthesized by the citric acid (CA) complexing method. Copper (II) nitrate and Cobalt (II) nitrate were employed in different molar ratios as the starting reactants to prepare three types of nano-catalysts. Well crystalline nano-catalysts were produced after a period of 3 hours by the calcination of CA–Cu–Co–O precursors at 550 °C. The phase morphologies and crystal composition of synthesized nano-catalysts were examined using Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS) and Fourier Transform Infrared Spectroscopy (FTIR) methods. The particle size of nano-catalysts was observed in the range of 90 nm–200 nm. The prepared nano-catalysts were used to formulate propellant samples of various compositions which showed high reactivity toward the combustion of HTPB/AP-based composite solid propellants. The catalytic effects on the decomposition of propellant samples were found to be significant at higher temperatures. The combustion characteristics of composite solid propellants were significantly improved by the incorporation of nano-catalysts. Out of the three catalysts studied in the present work, CuCo-I was found to be the better catalyst in regard to thermal decomposition and burning nature of composite solid propellants. The improved performance of composite solid propellant can be attributed to the high crystallinity, low agglomeration and lowering the decomposition temperature of oxidizer by the addition of CuCo-I nano-catalyst.

TG–MS study on the kinetics and mechanism of thermal decomposition of copper ethylamine chromate, a new precursor for copper chromite catalyst

Copper chromite is a well-known burn rate modifier for the combustion of composite solid propellants. In this study, basic copper ethylamine chromate (CEC), a new precursor for copper chromite catalyst, was synthesized by precipitation method. The thermal decomposition of the precursor was followed by thermogravimetry–mass spectroscopy (TG–MS) and X-ray diffraction techniques and compared with that of copper ammonium chromate, a conventional precursor for copper chromite catalyst. TG–MS analysis for the decomposition of CEC revealed that the decomposition starts with the liberation of ethylamine. The change in enthalpy for the decomposition reaction of copper ethylamine chromate was higher than that of copper ammonium chromate due to the oxidation of ethyl group. The reducing atmosphere created by the presence of carbon during the decomposition of CEC produced a mixture of Cu, CuCr2O4, CuCrO2 and CuO, while the oxidizing atmosphere of copper ammonium chromate produced a mixture of CuCr2O4 and CuO. Mechanistic study based on Criado and Coats–Redfern methods showed that CEC follows random nucleation (F1) mechanism as the rate-determining step for the thermal decomposition process.

Evaluation of Potassium Perchlorate as a Burning Rate Modifier in Composite Propellant Formulations

Evaluation of Potassium Perchlorate as a Burning Rate Modifier in Composite Propellant Formulations

Chemically Collapsible Mandrel for Solid Rocket Motor Processing

Composite propellant mainly consists of two parts, binder matrix (prepolymer, plasticizer, cross linker, antioxidant and curative etc.) and solid ingredients (oxidizer, metal fuel, burn rate modifier, combustion stabilizer etc.). Its processing involves several stages like ingredient preparation (grinding, 1.1 Hazard Division – 1.1 HD), mixing (1.1 HD), casting (1.1 HD), curing (1.3 HD) and extraction (1.3 HD). Each and every process is very hazardous. Removal of any of the mentioned step will be a great achievement for solid rocket motor processing. Mandrel is used to give proper grain geometry. But for metal mandrel, its extraction process (1.3 HD) is very dangerous. Proper safety precaution should be taken to perform the said operation. Also, for a metal mandrel, it is very difficult to develop intricate grain geometry due to extraction problem. This paper mainly deals with casting techniques of propellants (case bonded or cartridge loaded) with a chemically collapsible mandrel. This mandrel is collapsed in presence of suitable chemicals, hence extraction step (1.3 HD) becomes simpler. As the extraction process is very easy, intricate grain geometry can be developed in solid rocket motor. The mandrel is cheap, recycleable and relatively lightweight compared to the metal mandrel, thus handling becomes very easy. The mandrel material and the dissolution solvent have no effect on the propellant, which will be confirmed by evaluation of physicochemical as well as ballistic properties measurement.

Activated charcoal: as burn rate modifier and its mechanism of action in non-metalized composite solid propellants

Modification of composite solid propellant burning rates becomes a requirement based on the necessities of a mission. Literature discusses about various burn rate modifiers which can modify the burning rates effectively. This paper attempts to understand the behavior and mechanism of (dry) activated charcoal (a recently reported burn rate modifier) in composite solid propellant combustion. Extensive experimental studies are performed to achieve this objective. Effects of activated charcoal are studied on the individual components (fuel and oxidizer) of a composite solid propellant. Its behavior when present at various locations in a sandwich propellant and the quenched surface structures these sandwich propellants is also studied. These studies are further extended to composite propellants as well. From these studies, it is concluded that activated charcoal acts on the primary diffusion flame and enhances the binder melt flow over the surface. The unique features observed with activated charcoal (enhancement in burning the rates is observed only at low pressures and burn rate pressure index reduced) are justified with the proposed mechanism and site of its action. Understanding the mechanism of activated charcoal provided an opportunity to tailor a propellant composition, with activated charcoal coated on ammonium perchlorate, which exhibited very high burning rates (17.34 mm/s at 70 bar) and a near plateau burning (n ~0.08) in the pressure range of 20–70 bar. Also, this paper proposes a mechanism, as to what causes a propellant to have a relatively larger binder melt flow and consequently lower n has been answered.

Studies on the role of iron oxide and copper chromite in solid propellant combustion

Iron oxide and copper chromite are the known burn rate enhancers used in a composite solid propellant. Lot of research has been carried out to understand the mechanism or location of action of the burn rate modifiers so as to better tailor the burning rate of a composite propellant. The literature is still very confusing in affirming the mechanism. Here, a systematic study has been carried out, by undertaking experiments at varying levels of combinations of the individual components (ammonium perchlorate, which is oxidizer and hydroxyl terminated poly butadiene, which is both fuel and binder) of composite solid propellant. Firstly, thermal gravimetric analysis, differential scanning calorimetry and burning rate measurements on the individual components are carried out to study the effect of iron oxide and copper chromite on the components themselves. It has been noticed that though both iron oxide and copper chromite are effective on ammonium perchlorate, iron oxide is slightly more effective than copper chromite. Also, copper chromite enhanced the binder melt flow, while iron oxide reduced it. These are followed-up by experiments on sandwich propellants, which give greater insight and enables better understanding of the behavior of iron oxide and copper chromite in composite propellants, as these are simple two-dimensional analogue of the composite solid propellants. Finally, experiments are carried out on the composite solid propellants to obtain a holistic understanding of the behavior/location of action of iron oxide and copper chromite in them. These studies are used to explain certain unexplained but observed phenomena, at the same time elucidating the location of action of these burn rate modifiers in composite solid propellant combustion. Based on these observations, it has been proposed that both iron oxide and copper chromite are primarily acting on the condensed phase. These studies are further complimented with experiments to analyze the thermal conductivity measurements of various propellant samples. This is pursued to understand the reason for the differences in burn rate pressure index for the composite propellants with iron oxide and with copper chromite. It has been understood from these studies that the thermal conductivity of a composite propellant is a key parameter, which affects the burn rate pressure index. Literature has never addressed it from this perspective.

Experimental Techniques to Study Linear Burning Rates of Heterogeneous Liquid Monopropellants

This paper presents methods used to investigate the combustion behavior of liquid monopropellants with or without additives, with a focus on nanoscale particles as burning rate modifiers in nitromethane. The combined effects of nanoscale aluminum and fumed silica on the burning rate were tested at pressures ranging from 3 to 13 MPa, using a pressure-based technique. Distinct differences in burning rate were observed between burns using a quartz-lined cavity and those employing steel. An analytical model was used to estimate the temperature profiles of quartz, steel, and layered strand burner tubes, indicating that the higher burning rates measured in the steel cavity were likely caused by a combination of heat transfer and catalytic effects. A mixture of 1% silica, 5% aluminum, and 94% nitromethane by weight produced burning rates that were 60–70% higher than those of neat nitromethane across the range of pressures. The close match between the burning rates of neat nitromethane gathered in this study and those taken from other researchers proves the utility of the pressure-based method, whereas the consistently measured burning rates of the aluminum and silica mixture prove the versatility of the method when extended to tests on suspended-particle mixtures.

Effects of nano-scale additives on the linear burning rate of nitromethane

This paper examines the effects of various nanoparticle additives on the combustion behavior of nitromethane, using a pressure-based method recently demonstrated by the authors to measure the linear burning rates of liquid monopropellants and heterogeneous mixtures with high precision. The linear burning rates of these mixtures were measured in a constant-volume system at chamber pressures ranging from 3 to 14 MPa, all without direct observation of the burning front. Nano-scale aluminum was used to increase the overall energy density of the mixture, fumed silica powder was used to increase the mixture thickness and encourage aluminum suspension, and nano-scale titania was also included based on its previous use as a burning rate modifier in solid propellants. The silica loading was varied from 1% to 3% by weight, aluminum was varied from 5% to 13.5% by weight, and titania was added at 1% by weight. The use of fumed silica yielded increased burning rates compared to those of neat nitromethane, and the pressure exponent of the burning rate curve shifted from lower to higher than the nitromethane baseline as more silica was added. This increased pressure sensitivity for mixtures containing 3% silica by weight was previously unobserved in similar studies by other groups and may be an effect of the higher specific surface area of the currently used silica. The subsequent addition of aluminum led to even faster burning rates and higher pressure exponents for all but one mixture. The addition of titania also led to elevated burning rates, with dramatically increased pressure sensitivity and rate inconsistency for chamber pressures above approximately 8 MPa but a decreased pressure sensitivity for the same mixture below 8 MPa. These changes in combustion behavior that accompanied titania were diminished by the presence of aluminum and completely negated in mixtures also containing fumed silica.

Factors Affecting Burning Rate of Hydroxy Terminated Polybutadiene Propellant

Burning rate is one of the most important characteristics of rocket propellants and it is affected by many factors including composition, pressure, initial temperature, oxidizer particles size and burning rate modifier. This research aims to study experimentally the effects of combustion chamber pressure, initial temperature and particles size of the oxidizer materialon the burning rate of solid composite propellant. Besides, study theoretically the effect of composition and catalyst used. In addition, this research aims to show the relationship between these factors and the burning rate in order to evaluate factor that is more effective on burning rate, so to calculate of burning rate as a function of this factor. Accordingly, thiscould be used to achieve ballistics characteristics required for rocket motor design and performance.

Experimental Investigation of High-Burning-Rate Composite Solid Propellants

B ECAUSE motor thrust depends on the product of the exposed burning surface area and the propellant burning rate, high burning rates provide the ability to generate high thrust levelswithout the need for elaborate grain designs that provide high-burning surface areas. Complex, high-surface-area grain designs suffer from the fact that they reduce volumetric loading fraction (the ratio of propellant volume to chamber volume), which is one of the leading reasons for missiles’ size and weight. In addition, complex grain designs are more subject to mechanical failure under the harsh operational conditions of high-thrust/high-acceleration missiles. For these reasons, high-burning-rate propellants provide an enabling technology for a number of important missions. Ideally, alternatives can be identified that lie within the hazards class 1.3 propellant classification such that handling is less involved and the devices are inherently safer to personnel working with the system. It is well known that burning rates increase as particle sizes are decreased because the flame zone lies closer to the propellant surface where it provides more subsurface heating which drives the overall process. Because ammonium perchlorate (AP) is the most common oxidizer used in today’s composite solid propellants, there are numerous studies [1–5] that have shown burning rates increase inversely with AP particle size. The well-known Beckstead et al. multiple-flamemodel predicted a substantial increase in burning rate as AP particle size was decreased [6]. For unimodal distributions, their results showed an asymptotic ‘premixed flame’ limit that was approached at AP particle sizes somewhat below 10 m. From a practical standpoint, propellant processing limits preclude the use of this variable to a significant extent. In addition, very fine AP powder is more hazardous; particle sizes less than 15 m are classified as explosive by the U.S. Department of Transportation. Despite these drawbacks, one of the most effective strategies to increase burning rate is to minimize AP particle size such that mix viscosity and the desired hazards classification are met. Aluminum powder is the most common fuel in composite solid propellants, and reduction of its particle size has similar effects in increasing burning rate as with AP. The effect of aluminum content and powder size on burning rate has been studied in the classical literature [7–9] and has been the subject of more recent literature [10,11] with the development of nano-aluminum (nAl). Nanoaluminum has been proven to considerably enhance propellant burning rates over coarse aluminum. Shalom et al. showed in [12] that replacement of half of a propellant formulation’s 18% (by weight) coarse aluminum with nano-aluminum or ultrafine aluminum (UFAl) increased the burning rate by 84%. Using a unimodal aluminum distribution to determine the effect of particle size, Galfetti et al. [13] showed that replacing all of the micron-size aluminum in an AP/Al/hydroxyl-terminated polybutadiene (HTPB) (68/15/17) propellant increased the burning rate by 100%. Dokhan et al. in [11] showed that the addition of UFAl increased burning rate and that a higher fine-to-coarse AP ratio, in addition to the UFAl, further enhanced burning rate. With only 20% of the aluminum loading being UFAl, Dokhan et al. [11] showed that a burning-rate increase of 160% was delivered by increasing the fine AP loading from 20 to 40% and that a further 38% increase in burning rate could be realized with a fine AP loading of 60%. In addition to the effect of the fine AP loading, Dokhan et al. [11,14] obtained results that showed, for bimodal cases, substantial burning-rate increases occur at UFAl loadings as small as 20% of the total aluminum loading. Burn-rate catalysts or ‘modifiers’ are another commonmethod for enhancing burning rates of composite solid propellants. Extensive research regarding burn-rate modifiers has been conducted since the second half of the 1960s [1,3,15–25]. It has been shown that Received 18 January 2012; revision received 23 April 2012; accepted for publication 28 April 2012. Copyright © 2012 by Timothy D. Manship, Stephen D. Heister, and Patrick T. O’Neil. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. Copies of this paper may be made for personal or internal use, on condition that the copier pay the $10.00 per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923; include the code 0748-4658/12 and $10.00 in correspondence with the CCC. ∗Graduate Student, School of Aeronautics and Astronautics, 500 Allison Road. Member AIAA. Professor, School of Aeronautics and Astronautics, 500 Allison Road. Associate Fellow AIAA. Graduate Student, School of Mechanical Engineering, 500 Allison Road. Member AIAA (Corresponding Author). JOURNAL OF PROPULSION AND POWER Vol. 28, No. 6, November–December 2012

Solution Combustion Synthesis of Nanosized Copper Chromite and Its Use as a Burn Rate Modifier in Solid Propellants

Nano sized copper chromite, which is used as a burn rate accelerator for solid propellants, was synthesized by the solution combustion process using citric acid and glycine as fuel. Pure spinel phase copper chromite (CuCr2O4) was synthesized, and the effect of different ratios of Cu-Cr ions in the initial reactant and various calcination temperatures on the final properties of the material were examined. The reaction time for the synthesis with glycine was lower compared to that with citric acid. The synthesized samples from both fuel cycles were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), BET surface area analysis, and scanning electron microscope (SEM). Commercial copper chromite that is currently used in solid propellant formulation was also characterized by the same techniques. XRD analysis shows that the pure spinel phase compound is formed by calcination at 700 degrees C for glycine fuel cycle and between 750 and 800 degrees C for citric acid cycle. XPS results indicate the variation of the oxidation state of copper in the final compound with a change in the Cu-Cr mole ratio. SEM images confirm the formation of nano size spherical shape particles. The variation of BET surface area with calcination temperature was studied for the solution combusted catalyst. Burn rate evaluation of synthesized catalyst was carried out and compared with the commercial catalyst. The comparison between BET surface area and the burn rate depicts that surface area difference caused the variation in burn rate between samples. The reason behind the reduction in surface area and the required modifications in the process are also described.

Scale-Up Effects of Nanoparticle Production on the Burning Rate of Composite Propellant

The use of catalytic nanoparticle additives in composite solid propellant as burning rate modifiers has received much research attention in recent years, and as the widespread application of nanoparticles becomes more practical, scale-up processing and testing will be required. This article investigates the potential benefits of various additive processing methods and their effects on the burning rate of propellant consisting of ammonium perchlorate and hydroxyl terminated polybutadiene. Titania was investigated herein, but many of the results should apply to any metal oxide catalyst. Depending on how the additive was processed, it was seen to be both an effective and ineffective burning rate modifier. The ideal processing method was determined, leading to a better understanding of how the additive interacts with the propellant. The physical properties of the additive agglomerations were found to be a link between the additive processing and its effectiveness. Specifically, sintering of the additive agglomerates during heat treating limited the dispersion of the additives, ultimately hindering their ability to modify burning rate. This article presents one of the first studies that conclusively demonstrates the link between the processing of nanoparticles and their effectiveness in modifying propellant burning rate.

Selection of burning rate modifiers for hydrazinium nitroformate

Species including N 2H 4, NH 3 and N 2O are known to be present near the surface of burning hydrazinium nitroformate (HNF). In this paper, planar laser induced fluorescence from the near surface region of burning HNF pellets is reported indicating the presence of NO 2. These four species are formed in the upper (foamy) layer of the solid phase. A burning rate modifier might be selected to induce reactions between the gaseous species in this layer. Selective catalytic reduction (SCR) is able to start highly exothermic reactions at relatively low temperatures. The SCR catalyst V 2O 5 increases the burning rate of HNF by a factor of 11 at 0.1 MPa. The pressure exponent is reduced to 0.28, far below the target value of 0.5 required for practical application of HNF in propellant formulations. As far as SCR catalysts have been tested as burning rate modifiers of HNF, they are effective, yet incompatible. To overcome this incompatibility remedies might possibly be found in high-temperature catalysts, or in coating particles.

Burning Characteristics of Polytetrahydrofuran-Based Composite Propellant

D EVELOPMENT of a wide variety of rockets has required development of propellants having a wide range of performance corresponding to the purposes for which they are used. Especially, a high burning rate propellant is neededwhen developing a high performance rocket motor. The use of burning rate modifiers, metal fuels, and high energetic materials is a typical method to obtain a high burning rate propellant. Recently, nanosized metal fuels [1–4] and high energetic materials [5,6] have been developed, and researchers have been investigating the burning characteristics of solid propellants using them [1–13]. Glycidyl azide polymer is a typical energetic binder characterized by the N3 chemical bond [5,6,9–11]. The burning characteristics of the glycidyl azide polymer-based propellant are superior to those of common propellants, such as the hydroxyl-terminated polybutadiene (HTPB)based propellant. However, it is presently difficult tomake a practical solid propellant using high energetic binders and nanosized metal fuels because these materials are expensive and cannot be massproduced. It is necessary to find an inexpensive material to obtain a high performance propellant. Another approach is the application of new nonenergetic materials as the propellant fuel-binder. For example, hydrogenated hydroxylterminated polyisoprene [14], polymethylmethacrylate [15], polyethylene [16,17], polyvinyl chloride [18,19], polycaprolactone [20], etc., are now being evaluated. The burning performances of propellants using these polymers are not inferior to those of the HTPB-based propellant. Polytetrahydrofuran (PTHF) is used as an ingredient for rubber products and is produced in several different molecular weights. This polymer is mass-produced commercially and inexpensive. The chemical properties of PTHF are shown in Table 1. The repeating unit of PTHF consists of a single bond and has one oxygen atom, four carbon atoms, and eight hydrogen atoms. PTHF has a hydroxide group on one side of the molecular chain of PTHF and a hydrogen atom on the other side. The molecular structure of PTHF is similar to that of HTPB. PTHF is not an energetic binder. However, it could be expected that the burning performance of a solid propellant could be improved by using PTHF as a binder, comparedwithHTPB, because the amount of oxygen atom per mole of PTHF is greater than that of HTPB. In this study, the burning rate characteristics of the PTHF-based composite propellant were investigated and compared with the characteristics of the HTPB-based composite propellant. According to the results, it was found that the performance of the PTHF-based composite propellant is superior to that of the HTPB-based propellant.

Studies on energetic compounds: Part 36: evaluation of transition metal salts of NTO as burning rate modifiers for HTPB-AN composite solid propellants

Transition metal [Mn(II), Fe(II), Fe(III), Co.(II), Ni(II), Cu(II) and Zn(II)] salts of 5-nitro-2,4-dihydro-3H-1,2,4-triaole-3-one (NTO) have been incorporated as ballistic modifiers in composite solid probellants (CSPs) of hydroxyl terminated polybutadiene (HTPB) – ammonium nitrate (AN). The steady burning rate of the propellants was considerably increased by the additives, Zn(NTO) 2 being the most efficient one. The condensed phase thermolysis of such propellants was studied using non-isothermal TGA and DTA and the effect of additives is evident from these studies also. Also, the effect of these additives on the non-isothermal heating of AN from room temperature to ∼300°C was studied using TGA and DTA. The additives lowers the decomposition temperature of AN considerably. DTA studies show that the additives alter the phase transition temperatures of AN. Heats of combustion of the modified propellants were found to be higher than for the control one.

Some Transition Metal Salts of 4,6‐Dinitrobenzofuroxan: Synthesis, Characterization and Evaluation of Their Properties

AbstractChromium, Iron and Copper salts of 4,6‐dinitrobenzofuroxan have been prepared by reacting sodium salt of 4,6‐dinitrobenzofuroxan with chromium nitrate nonahydrate, ferric nitrate nonahydrate and cupric nitrate trihydrate, respectively. The compounds have been characterized by elemental analysis, spectral data (IR and NMR) and metal content. Some properties including thermal and explosive behaviour of these compounds have been investigated and reported. Further, these molecules have also been investigated in composite propellants as burn‐rate modifiers. The preliminary data suggest that iron salt of 4,6‐dinitrobenzofuroxan is better than ferric oxide, generally used as a burn‐rate modifier for hydroxy‐terminated polybutadiene (HTPB) based composite propellants.

Studies of energetic compounds, part 29: effect of NTO and its salts on the combustion and condensed phase thermolysis of composite solid propellants, HTPB-AP

The effect of 5-nitro-2,4-dihydro-3H-1,2,4-triazole-3-one (NTO) and two of its transition metal salts, namely Cu(NTO) 2 and Fe(NTO) 3, during the combustion of composite solid propellants (CSPs) of hydroxyl-terminated polybutadiene (HTPB) and ammonium perchlorate (AP) has been studied. The activities of Cu(NTO) 2 and Fe(NTO) 3 have been compared with those of CuO and Fe 2O 3 at their equivalent metal concentrations. The processing parameters and mechanical properties of the propellants were also evaluated using Cu(NTO) 2 and Fe(NTO) 3 as additives, and a comparison has been made with that of copper chromite (CC) and active iron oxide (AIO) at pilot plant scale. The safety aspects of using these energetic salts as burning-rate modifiers have been studied in terms of the impact-sensitivity of the modified propellants. An attempt has been made to evaluate experimentally the condensed phase activity of these additives during the slow thermolysis of propellants, as well as AP. Rapid thermolysis of the propellants and AP has been studied using measurements of ignition delay.

Studies on energetic compounds. Part- 34. Effect of some BEMN complexes on the condensed phase thermolysis of HTPB-AP composite solid propellants

Effect of some bis(ethylenediamine)metal nitrate (BEMN) complexes, i.e. [M(en) 2 [(NO 3 ) 2 (where, M = Cu, Co, Ni and Zn and en = ethylenediamine) during the condensed phase thermolysis of hydroxyl-terminated polybutadiene(HTPB) and ammonium perchlorate (AP) composite solid propellants (CSPs) has been studied using TG and DTA. The results indicate that the thermolysis of propellants is affected when these energetic complexes are used as burning rate modifiers in small percentage (2% by wt). Ignition delay (t i d ) measurements on unmodified and modified propellants have been conducted to examine the effect of these additives during the rapid thermolysis of propellants. The response of the modified propellants to drop weight impact is determined to know the safety aspects. The effect of these additives on thermal decomposition of oxidizer (AP) is also investigated. Copper and cobalt complexes show considerable effect while nickel and zinc moderate effect on both propellants and AP decomposition.