Double-base Solid Propellant Research Articles

A comprehensive investigation of the impact of carbon-supported metal complexes of triaminoguanidine on the characteristics of a double-base propellant

ABSTRACT In this study, triaminoguanidine complexes grafted onto activated carbon (AC-TAG-Fe and AC-TAG-Co) were designed and investigated for their catalytic effect on the thermolysis of a double base propellant consisting of nitrocellulose (NC) and diethylene glycol dinitrate (DEGDN). The successful synthesis of transition metal complexes with triaminoguanidine and their subsequent grafting onto activated carbon were confirmed using various analytical techniques, including Fourier Transform Infrared Spectroscopy, Raman Spectroscopy, X-ray Diffraction, and Scanning Electron Microscopy. Thermal characterization using Thermogravimetric Analysis and Differential Scanning Calorimetry provided valuable insights into the thermal properties and reactivity of the elaborated NC/DEGDN-based composites. Importantly, the addition of various additives resulted in notable improvements in both the enthalpy of reaction and density. Isoconversional kinetic studies revealed that the incorporation of TAG-Fe and TAG-Co complexes reduced the apparent activation energy of the NC/DEGDN composite from 137.4 kJ/mol to 135.4 kJ/mol and 114.8 kJ/mol, respectively, suggesting their catalytic effect. Furthermore, it is found that the addition of activated carbon (AC) resulted in an increase in activation energy to 154 kJ/mol, whereas grafting TAG-Fe and TAG-Co complexes onto AC as a catalytic support subsequently reduced activation energy to 119 kJ/mol and 112 kJ/mol, respectively. Overall, this research serves as a valuable reference for future studies focusing on investigating the catalytic combustion characteristics of double-base solid propellants.

A simple and safe approach for simultaneous spectrophotometric determination of nitroglycerin and nitrocellulose in double base solid propellants.

An accurate, simple and safe method was developed for simultaneous determination of nitroglycerine (NG) and nitrocellulose (NC) in double base solid propellants (DB propellants). The proposed method is based on alkaline hydrolysis of NG and NC, and followed by colored reaction of released nitrite ion with p-nitroaniline in the presence of diphenylamine in acidic media and produce azo dye. The absorbance of the azo dye was measured at 534nm. Two sets of reaction conditions were developed. In the first set, at room temperature, only NG was hydrolyzed and calibration curve obtained. In the second set, at 60℃, NG and NC were hydrolyzed simultaneously. Based on obtained amount for the NG at room temperature, and total amount of NG and NC at 60℃, the amount of NC was determined by using stoichiometric equations. The calibration curve was linear over the concentration ranges of 0.2-5.0, 0.5-10μgmL-1 for NG and NC, respectively. The proposed method was successfully applied for the determination of NG and NC in DB propellants with good recoveries ranged from 99 to 101%, and RSD less than 2.0%. The method statistically compared based on t- and F-tests with those obtained in according to military standard method (MIL-STD-286). The results showed that the proposed method offers an accuracy and reliable approach for the determination of these compounds in DB propellants, and can be suggested as a routine method in military quality control laboratories.

Development of spectrophotometric method for simultaneous determination of copper β-resorcylate, lead β-resorcylate and lead oxide in double base solid propellants using mean centering of ratio spectra technique

Development of spectrophotometric method for simultaneous determination of copper β-resorcylate, lead β-resorcylate and lead oxide in double base solid propellants using mean centering of ratio spectra technique

A SIMPLE AND SELECTIVE SPECTROPHOTOMETRIC METHOD FOR DETERMINATION OF ETHYL CENTRALITE AS STABILIZER IN DOUBLE BASE SOLID PROPELLANTS: A COMPARATIVE STUDY WITH HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

A SIMPLE AND SELECTIVE SPECTROPHOTOMETRIC METHOD FOR DETERMINATION OF ETHYL CENTRALITE AS STABILIZER IN DOUBLE BASE SOLID PROPELLANTS: A COMPARATIVE STUDY WITH HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

Thermal Behavior and Decomposition Mechanism of Double-Base Solid Propellants by Kinetic Methods

Thermal Behavior and Decomposition Mechanism of Double-Base Solid Propellants by Kinetic Methods

A Green Approach for Photometric Determination of Copper β-Resorcylate in Double Base Solid Propellants

This paper describes the applicability of micellar media instead of extraction steps with toxic solvents for direct determination of copper beta-resorcylate as burning rate catalyst in double base propellant (DB propellant). The method is based on a simple and safe sample preparation of DB propellant, and then complex formation of copper ion with Diethyldithiocarbamate (DDTC) in the presence of sodium dodecyl sulfate (SDS) as a micellar media. Under optimal conditions, at λmax= 445 nm, the calibration graph was linear in the range of 0.25-4.5 µg mL-1 for copper with detection limits 0.125 µg mL-1. The validity of the method was evaluated by means of the data statistical analysis. For this purpose, the method was applied to the determination of copper beta-resorcylate in DB propellant and the results were statistically compared based on t- and F-tests with those obtained by the by ICP-AES. There was no significant difference between the mean values and the precisions of the two methods at the 95% confidence level. The results showed that the proposed method offers an accuracy and reliable approach for the determination of copper β-resorcylate in DB propellant, and can be suggested as a routine method in military quality control laboratories.

A simple and selective approach for determination of titanium dioxide in double base solid propellants: methodology for method validation

ABSTRACT In this work, we developed and validated a simple and selective method for the determination of titanium dioxide in double base solid (DB propellants). The method is based on complex formation of Ti(IV) with hydrogen peroxide in acidic media and monitoring absorbance of colored product by spectrophotometric technique at 407 nm. Under optimal conditions, at λmax = 407 nm, the linear range of determination of Ti(IV) was 5.0–100 µg mL−1 with detection limits of 3.0 µg mL−1. The validity of the method was evaluated by means of the data statistical analysis. For this purpose, the method was applied to the determination of titanium dioxide (TiO2) in DB propellants and the results were statistically compared with those obtained by the by ICP-AES method using t- and F-tests. There was no significant difference between the mean values and the precisions of the two methods at the 95% confidence level. The results showed that the proposed method offers an accurate and reliable approach for the determination of titanium dioxide in DB propellants, and can be suggested as a routine method in military quality control laboratories.

Study on Main curvature of Stress Relaxation Modulus of a Double-base solid propellant

The mechanical properties of a double-base solid propellant under quasi-static and dynamic conditions are studied experimentally. According to the time-temperature equivalence of a double-base solid propellant, the main curve of stress relaxation modulus and temperature-dependent material parameters are obtained by using the stress relaxation test results at different temperatures. Based on the analysis of the temperature spectrum of a double-base solid propellant material, the main curve of stress relaxation modulus and temperature-dependent material parameters of the double-base solid propellant material are obtained by using the equivalent principle. The results show that the dynamic test results are better. The database of the dynamic stress relaxation modulus main curve should be used as the basic parameters of the constitutive model analysis and the structural integrity analysis of the double-base solid propellant, which lay the foundation for the type selection and the structural integrity analysis of double-base solid propellant grain.

Synthesis of Novel Plasticizers Based on Poly(ε-caprolactone) and A Consideration of Their Influence on Nitroglycerine Migration in Double Base Solid Propellants

Synthesis of Novel Plasticizers Based on Poly(ε-caprolactone) and A Consideration of Their Influence on Nitroglycerine Migration in Double Base Solid Propellants

Heat balance evaluation of double-base solid propellant combustion using thermography and laser heating on a burning surface

A new method is proposed using laser heating and thermography for estimating the heat transfer balance for burning solid propellant: heat production rate on burning surface Q˙s, heat flux from burning surface to solid phase Λp, and heat flux rate from flame to burning surface Hf. Hf is determined from the correlation between burning rate and power density of laser heating on burning surface; Λp is evaluated using the burning surface temperature measured with thermography. Double-base propellant is tested in a combustion chamber having a laser-introducing window, and is irradiated with an 808-nm laser at laser power densities ranging from 0.3 to 0.8 W/mm2 with a back-pressure range from 0.02 to 0.60 MPa. The proposed method shows heat flux from burning surface to burning surface Hf of 1.7 W/mm2, heat production rate on burning surface Q˙s of 4.9 W/mm2, and heat flux from burning surface to solid phase Λp of 6.6 W/mm2 at a back pressure of 0.60 MPa. Laser power attenuation due to the flame is determined to evaluate the influence of laser power attenuation on the estimation of heat flux rate from flame to burning surface. The experiment shows that errors originating from laser power attenuation due to the flame are below 18%.

Determination of Glass Transition Temperature of Double-base Rocket Propellants with the Use of Dynamic Mechanical Analysis

The paper presents results of Dynamic Mechanical Analysis (DMA) of double-base (DB) solid rocket propellant with special attention paid to determining the glass transition temperature. The presented experiments were carried out with the use of Netzsch DMA 242C analyzer with the dual cantilever operation mode. Advantages and drawbacks of the DMA method, measured values, as well as important characteristics of solid double-base rocket propellants were briefly described. Obtained values of the storage modulus E', the loss modulus E, and tanδ were represented in dependence on temperature. The glass transition temperature of the tested propellant was determined according to NATO standard 4540 [7] at the peak of the loss modulus curve.

Effects of grain size and temperature of double base solid propellants on internal ballistics performance

A conventional bullet or projectile driven by solid fuels accelerates in the barrel and reaches certain muzzle velocity, spin and propulsion energies. Combustion characteristics of solid fuels are the most important factor affecting bullet performance and maximum range. In this work, double base solid propellants of spherical geometry within the ranges of 300–425, 425–500, 500–600, 600–710 and 710–850μm in diameter and temperatures of −60, −40, −20, 0, 20, 40 and 60°C, were investigated in terms of the effects of grain size and temperature on burn rate, internal barrel pressure and bullet velocity. Solid fuel properties such as fuel heat of combustion, density, combustion temperature, particle size and mass were measured. In a constant volume chamber, burn rate was measured for each fuel sample at different pressure and temperature. In addition, cartridges of 7.62mm in diameter were made using sample solid fuels, and shooting tests were carried out with a special test barrel. In the tests, strains along the barrel were determined using strain gauges and the muzzle exit velocity of the bullet was measured with a doppler radar for calibrations. It was seen that the increase of fuel temperature and decrease of particle size increased burn rate, internal barrel pressure and bullet velocity.

Effect of Initial Temperature on the Interior Ballistics of a 120-mm Mortar System

In this study, the effect of the initial temperature of a 120-mm mortar system on its interior ballistics was investigated using four different experiments: temperature-conditioned closed bomb firings for determining the temperature sensitivity of the ignition cartridge's M48 double-base propellant and instrumented firings of temperature-conditioned flash tubes, ignition cartridges, and an instrumented mortar simulator (IMS). The results of these experiments reveal that, for initial temperatures of –12 °C and greater, the mortar system and its subcomponents exhibited regular initial-temperature-dependent behavior, with increasing initial temperature causing monotonically increasing propellant burning rates and monotonically decreasing ignition delays, which produce monotonically increasing system pressures and pressure differentials in the flashtube, ignition cartridge, and IMS. However, some anomalous behavior was discovered for temperatures around –46 °C. At this initial temperature, the closed bomb firings indicated that brittle fracture of the M48 propellant granules used in the ignition cartridge occurs. This phenomenon explains the occurrence in the IMS firings of dramatically increased variation in pressure-time behavior and projectile muzzle velocity for charge 4 firings as compared to higher temperatures, as well as the occurrence of maximum tube pressures for –46 °C firings, being greater than those for 21 °C firings for charge 0. However, one of the –47 °C closed bomb firings does not exhibit evidence of grain fracture and yet produces a higher propellant burning rate than the –12 °C firings, suggesting that a fundamental change in reaction kinetics or flame structure is occurring at extremely low temperatures. This supposition is bolstered by evidence of a liquid layer existing on the surface of M48 propellant granules ejected from the ignition cartridge during the –46 °C firings—a phenomenon that does not occur at the higher initial temperatures and is not theorized to occur in double-base solid propellant combustion. Based on the flash tube experiments alone, the flash tube was determined to have a weak effect on the initial-temperature-dependent behavior of the mortar system; however, IMS testing with two different flash tube configurations revealed significant differences in longitudinal pressure wave amplitude and projectile muzzle velocity in charge 4 firings between the two configurations at –46 °C, suggesting that the uniformity of combustion product discharge from the flash tube could significantly affect the performance of the mortar at low temperatures.

Research on Creep Characteristics of the Double-Base Solid Propellant

The uniaxial tensile creep tests of the double-base solid propellant specimens were carried out at 450C under five different stress levels. The viscoelastic models such as three parameters solid model, Burgers model, generalized Kelvin model, five parameters solid model and exponential model were adopted. The computation equation that can describe the strain rate of the second creep stages of the double-base solid propellant under different applied stress levels was founded on the basis of these creep tests, and the adaptability of the five models on creep characteristics of the double-base solid propellant were studied. The study results shows that the five models can show good agreement with second creep course of propellant under different applied stress levels, but the generalized Kelvin model may have optimal characterize creep curve of the double-base solid propellant.

An elasto-viscoplastic analysis of direct extrusion of a double base solid propellant

In this study, three-dimensional modelling of extrusion forming of a double base solid rocket propellant is performed on Ansys(R) finite element analysis program. Considering the contact effects and the time dependent viscous and plastic behaviour, the solid propellant is assumed to obey the large deformation elasto-viscoplastic material response during direct extrusion process. The deformed shape, hydrostatic pressure, contact stress, equivalent stress, total strain values are determined from the simulation in order to get insight into the mechanical extremity that the propellant has undergone during processing. Hydrostatic pressure and contact stress distributions have been found to be important parameters due to safety reasons of the nitro-glycerine content in the bulk of the propellant.

Solid propellants burning enhancement using foil embedding method

AbstractThe method of metal embedding is widely employed in solid propellant motors with end-burning configuration, thereby significantly improving the burning rate of the propellants. In this study, the cylindrical foil embedding method is applied to double-base solid propellant, as a new method, and the effects of the type and thickness of the foil on the burning surface, as well as the burning rate, are experimentally investigated. It is shown that by using the foil embedding method, the burning characteristics of solid propellants can be improved. Results have been compared to some available data. To the best of the author’s knowledge there are no published data available on this method.

The formulation and testing of new solid propellant mixture (DB + x%BP) for a new MEMS-based microthruster

A new planar structure of solid propellant micro-rocket for micro-spacecraft and micro-air-vehicle applications is reported in this paper. We have successfully fabricated an array of micro-rockets using MEMS technology. For a low-power consumption, the micro-igniter used here is a resistor deposited on a low tensile stress thin membrane to ensure a good heat transfer to the propellant. Experimental tests of ignition and microcombustion employing double-base (DB) solid propellant mixed with black-powder (BP) are reported and discussed. Tests have showed successful and continuum combustion of about 1.3 mm diameter during few 100 ms from BP ratio in the mixture ( x) of 10%. Thrust force delivered by considered structure dimensions, is ranging from 0.1 to 1 mN for x = 10%, 20% and 30%. We expect that this planar structure will deliver a suitable thrust force of few 10 mN when reducing micro-nozzle throat dimensions.

Thermophysical and Chemical Processes of Burning of Double-Base Solid Propellants under External Irradiation

A piece-wise linear function for the dependence of the burning rate on the radiant flux and its break point are important burning characteristics of double base propellants under external irradiation. The Fourier equation can be used to analyze the burning characteristics, but some early models resulted in discontinuous characteristic parameters at the break point. In this paper, a new model, where the loss of external irradiation energy was considered above the surface of condensed phase, would be used to resolve the contradiction. The burning characteristics of 1040, 1041, N-5 and N propellants were analyzed.

Improvements in the Chemical Stability of Double-Base Solid Rocket Propellants

The effect of copper, compared with lead salt-based ballistic modie ers on the reaction of the propellant stabilizers, para-nitro-N-methylaniline and 2-nitrodiphenylamine, during the aging of nitroglycerin solutions and on the reactions of these stabilizers with the individual reactive species known to be generated during double-base propellant decomposition, namely NO 2, HNO2, and HNO3, have been thoroughly investigated in an attempt to deduce some key parameters that ine uence the reactions that take place in these propellant systems during aging. It was found that copper modie ers greatly differ from lead ones in their effect on the depletion of stabilizers and in their reactivity toward the reactive species. All of the copper salts have a dramatic effect on the reactions of propellant stabilizers. They cause more rapid depletion of stabilizers when compared with that produced by lead salts, the effect of basic copper salicylate being more dramatic than that of copper oxide. The results have shown thattheorganicmoiety oftheballisticmodie erplaysanimportantroleinitsine uenceonthereactionsofstabilizers with propellant degradation species, and that the higher reactivity of copper salts compared with that of lead salts is attributable to the combined effect of both the copper ion and the salt anion. In particular, this investigation has helped contribute information on the propellant compositions that should fule ll the requirements for propellant service use. To overcome the deleterious effect of some copper modie ers on the chemical stability of double-base propellants, the stabilizer system must include resorcinol and the copper salt should be used at a low level. OPPER salts, in combination with lead salt-based ballistic modie ers, are used in nitroglycerin-(NC)-based propellants to modify the combustion characteristics of solid rocket propellants. Nearly all solid propellants based on nitrate esters contain a uniformly distributed stabilizer. The function of the stabilizer is the removal of NO 2, which is formed as a primary decomposition product during the storage of propellants, 1 and which would otherwise autocatalytically accelerate the decomposition. Stabilizer mixture systems are widely used in double-base rocket propellant formulations,wheretheyhavebeenfound 2 tobemosteffectiveinprolonging the crack-free life of the propellant grain during storage. It is generally assumed that the more reactive stabilizer reacts rapidly with the propellantdegradation productsduring theearly stagesofaging, whereas the second stabilizer reacts more slowly. Stabilizerslikeresorcinol,andthe combinationofresorcinolwith other stabilizers, are reported to be useful. 3,4 The effectiveness of resorcinolhasbeenexplained 5 asbeingaresultofactivatedaromatic ring formation, which helps in the absorption of nitrogen oxides quickly and more effectively, resulting in further control of growth of autocatalytic reactions. It was indicated 6 that the chemical stability of double-base propellants is signie cantly ine uenced by different lead-based ballistic modie ers, and that the organic moiety of the ballistic modie er is an important ine uence on the reactions of the stabilizers. In this work, systematic investigations have been carried out to obtain a deeper insight into 1 ) a comparison of the effect of lead and copper salt-based modie ers on the reaction of stabilizers commonly used in the cast double-base (CDB) rocket propellants, namely para-nitro-N-methylaniline (pNMA) and 2-nitrodiphenylamine (2NDPA),duringtheagingofNGsolutionsin acetonitrile-containing identical quantities of the ballistic modie ers that are also commonly used in the propellant matrix, and 2 )a study of the effect of copper modie ers on the reactions of the stabilizers with propellant degradation products (namelyNO2, HNO2, and HNO3). Studying the reaction of these compounds is very impor

Stabilizer reactions in cast double base rocket propellants. Part VII: Effect of lead‐based ballistic modifiers on the reactions of propellant stabilizers during simulated aging of cast double base solid propellants

AbstractThe effect of lead‐based ballistic modifiers on the reactions of stabilizers during accelerated aging at 80°C and 90°C of cast double base propellants has been investigated in order to obtain information on the reactions taking place in these propellant systems. It was found that the ballistic modifiers lead β‐resorcylate (LBR) and lead salicylate (LS) have a significant effect on the depletion of para‐nitro‐N‐methylaniline (pNMA) and 2‐nitrodiphenylamine (2NDPA). Model studies have shown that both LBR and LS reduce the rate of depletion of pNMA to a similar degree, but only LBR reduces the rate of depletion of 2NDPA, with LS having the opposite effect.