Single-base Propellants Research Articles

Synthesis and crystal characterization of novel fulleropyrrolidines and their potential application as nitrocellulose-based propellants stabilizer

Safe storage of nitrocellulose-based propellants has become challenging due to their requirements of extreme storage and operational environments. Thus, developing new high-performance stabilizers is urgently needed to improve the stability of propellants. With their excellent thermal stability and strong ability to clear free radicals, fullerene stabilizers for nitrocellulose-based propellants were synthesized using the Prato reaction. Their molecular structures were confirmed by 1H NMR, 13C NMR, FT-IR, UV–Vis, HRMS, and single-crystal X-ray diffraction. Their compatibility and stability in nitrocellulose were investigated using differential scanning calorimetry, methyl-violet, vacuum stability, and weight loss tests. Results indicated that the new fullerene stabilizers had excellent compatibility with nitrocellulose and their stability were better than the conventional stabilizers C2 and DPA. Moreover, their stability mechanism was investigated by electron paramagnetic resonance spectroscopy and FT-IR analysis. The results turned out that new fullerene stabilizers could absorb nitrogen oxides and effectively eliminate the nitroxyl radicals released from nitrocellulose decomposition. Therefore, these new multifunctional fullerene derivatives can be used as novel stabilizers and apply to single and double base propellants.

Experimental and Theoretical Determination of Water-Jet Velocity for Disruptor Application Using High Speed Videography

Experimental and theoretical determination of water-jet velocity using high speed videography for disruptor application is reported in this paper. Water-jet disruptor extensively uses the water as a liquid projectile. It helps to destroy improvised explosive devices (IEDs) or explosive devices (EDs) by breaking detonating cord in the system, making it non-operational. The use of such system against suspected objects is a fashion that continues to be met tremendous achievement. Such a device is also known as explosive ordnance disposal (EOD) disruptor. It is used by bomb technicians or squad to make disable and/or neutralize at a safe distance. The primary purpose of an EOD disruptor is to remotely open or provide destruction to suspected objects. To “remotely open” is to open the suspect objects, exposing their contents. “Provide destruction” means penetrating, cutting, or removing the components of the fusing system in order to make them disable. A secondary purpose of a disruptor is to create a means of access (for example, through a window or door of vehicle or into a trunk). Double and single base propellants are used in the experimental trials for assessing water-jet velocities. An attempt has been made to validate the water-jet velocity using experimentally high speed videography for the first time and making its theoretical analysis by conducting the various trials at a laboratory with different propellants. The stand-off distance between disruptor and target is 0.5 m. This kind of research work is not reported in open access till the date. This is the newness of this research work. The experimental water-jet velocity for single base propellant varies from 349.63 to 503.56 m/s and for double base propellant it varies from 515.07 to 890 m/s. The theoretical water-jet velocity for single base and double base propellant works out to be as 616.44 m/s and 692.62 m/s respectively. From this research study, it is concluded that there is good agreement between theoretical and experimental results.

One-step preparation of graphene nanosheets via deflagration of obsoleted energetic materials

Herein, we report the large-scale preparation of graphene nanosheets via the deflagration of an obsoleted single base propellant in the presence of dibutyl phthalate (DBP) aiming at decreasing the oxygen balance. The high ambient pressure and high temperature generated during the deflagration process provided sufficient conditions for the efficient formation of carbon atoms and the subsequent shaping of graphene nanosheets. The prepared graphene nanosheets were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and X-ray diffraction (XRD). This simple method is promising for future large-scale and cost-effective production of graphene nanosheets, as well as for the disposal of obsoleted energetic materials.

Application of near infrared spectroscopy in fast assay of liquid components in single-base propellant intermediates

The liquid components (including water and residual solvent (RS)) content is an important quality indicator of single-base propellant intermediates. This work presented a quick method for the determination of water and RS content in single-base propellant intermediates employing near infrared (NIR) spectroscopy in place of costly, laborious and time-consuming reference analysis (gas chromatography, GC). The Monte-Carlo uninformative variable elimination (MCUVE) and the backward interval partial least squares (Bi-PLS) were applied for characteristic variable selection during the modeling process. In this case, Bi-PLS algorithm showed the superiority when compared with MCUVE method for multivariate calibration due to sample intrinsic inhomogeneity. The correlation coefficient of the calibration and prediction (Rc, Rp), and the root mean square error of calibration and prediction (RMSEC, RMSEP) of the obtained optimum models by Bi-PLS algorithm were 0.98, 0.99, 0.28%, 0.36% for water, and 0.99, 0.99, 0.34%, 0.42% for RS, respectively. No significant difference existed between the reference and NIR method according to the result of a paired t-test. In addition, the repeatability of the NIR method met the requirement of the reference method. The results indicated that the NIR method built in this work would have a bright prospect in rapid measurement of liquid components content single-base propellant intermediates.

Rapid quantification of stabilizing agents in single-base propellants using near infrared spectroscopy

The standard analytical method (gas chromatography, GC) applied for determination of stabilizing agents including diphenylamine (DPA) and N,N′-Dimethyl carbanilide (C2) in single-base propellants always costs too much time and toxic regents, and forms harmful wastes. This study investigated the feasibility of using near infrared (NIR) spectroscopy as a fast and green substitute. The samples were partitioned into calibration and validation subsets using the joint x–y distance (SPXY) algorithm. The backward interval partial least squares (biPLS) algorithm was used for wavenumber region selection during the model development. The correlation coefficient of validation (Rval), the root mean square error of prediction (RMSEP) and the ratio of standard deviation of the validation set to standard error of prediction (RPD) of the developed models were 0.987, 0.201 and 5.29 for DPA, and 0.976, 0.227 and 6.12 for C2, separately. The repeatability of the NIR methods satisfied the requirement of the standard method. The results showed that the developed NIR models exhibited good predictive performance and repeatability, and would have a promising future in predicting stabilizing agents content of single-base propellants due to high speed, convenience and no pretreatment.

Stabilizer Depletion in Single Base Propellant from Unexploded Ordnance

AbstractDecomposition of nitrocellulose‐based propellant is a well‐known problem that results in insufficient shelf‐life of the ammunition if the propellant is not stabilized with appropriate materials. To investigate the influence of storage conditions on the shelf life of old propellant powder HPLC analytics according to AOP‐48 were carried out to determine the stabilizer consumption at different temperatures. The ingredients of the propellant were also analyzed. The results show that the examined propellant samples from WW II production are still containing stabilizer. Humidity in combination with elevated temperature seems to be the most influencing parameter for decomposition of this type. The analyzed propellants seem to be stable even after about 70 years under bad storage conditions. You might draw conclusions from these results for modern time propellant powders, which are stored under controlled conditions.

N차 반응속도 모델을 적용한 단기추진제의 저장수명 예측

Abstract Single-base propellants contain a single energetic component: nitrocellulose. Accurate predictions of propellant shelf-life should result in cost savings in terms of human and material resources. This study derived an optimized kinetic model reaction order that described stabilizer consumption and estimated propellant shelf-life. High temperature accelerated aging tests gave an optimum reaction order value of 1.15481, from which the minimum standard error of a linear regression estimate of 16.284 was obtained. At normal storage temperature of 21 – 30°C,propellants should have a safe shelf-life of 140 years, and a minimum of 35 years. It is necessary to consider thetemperature range in ammunition storage areas to predict propellant shelf-life more accurately. Key Words : Kinetic model, Nitrocellulose, n-th order, Propellant, Stabilizer, Shelf-life * Corresponding Author : Sang-Bong Lee (Defense Agency for Technology and Quality) Tel: +82-53-757-3062 email: sb81.lee@dtaq.re.krReceived April 14, 2015 Accepted May 7, 2015Revised May 6, 2015Published May 31, 2015

Study on the Burning of the Modified Single Base Gun Propellant

The modified single base gun propellant (MSBP) was prepared from single base propellant grain by impregnation with blasting oil, followed by deterring with deterrent in water medium. The combustion performance of this propellant was investigated by means of closed-bomb, interior ballistic and barrel erosion test. The interior ballistic property of this propellant after accelerated aging at high temperature was researched, too. Compared with the single base gun propellant, the MSBP burns more progressively and the value of Pr increases from 0.035 to 0.445. The interior ballistic performance for this propellant charge is improved obviously. The muzzle velocity increases by 5.0% from 886.6 m/s to 931.3 m/s. The MSBP has the characteristic of low temperature sensitivity and the barrel erosion of this propellant decreases by 16.6% at least. The interior ballistic performance of the MSBP has slightly changes after long-term storage. The MSBP has the advantages of higher muzzle velocity, higher combustion progressivity, low temperature sensitivity, low erosion and it can be satisfied with the actual storage demand.

Application of a nanostructured supramolecular solvent for the microextraction of diphenylamine and its mono-nitrated derivatives from unburned single-base propellants.

A supramolecular solvent made up of nano-sized inverted hexagonal aggregates of 1-octanol is proposed for the microextraction of diphenylamine and its mono-nitrated derivatives in unburned single-base propellants. The procedure included the extraction of sub-gram quantities (30 mg) of homogenized propellant with 1.5 mL of the supramolecular solvent. Several conditions affecting extraction efficiency, for example the concentrations of the major components of the supramolecular solvent (tetrahydrofuran and alkanol), alkanol type, solvent pH, and extraction time, were investigated and optimized. The main forces for the microextraction of analytes in the nanostructured supramolecular solvent include both dispersion and hydrogen bond interactions. This mixed-mode mechanism resulted in high extraction efficiencies reaching low method detection limits (0.005-0.012 mg/g) without the need for extract evaporation. Under the optimum conditions, recoveries in samples ranged between about 82.6 and 98.7%. Compared to the reference method, the proposed method is simple and rapid, delivering accurate and precise results, and can be applied for routine determination of diphenylamine and its derivatives in propellants. The precision of the method, expressed as relative standard deviation, was about 4.3-10.9%.

Predicting the Shelf-Life of Single Base Propellants

Ammunitions stored in war fields have lifespans that are related to the single base propellants, as Nitrocellulose (NC), the main component of propelling gunpowder, decomposes naturally into an unstable substance, similar to other nitric acid esters. Decomposition is inevitable; however a decomposition product (NO2, NO3, and HNO3) and tranquillizer DPA (Diphenylamine), which have high reactivity, can be added to a propellant to restrain the induction of automatic catalysis by a decomposition product. The decay rate of the tranquillizer is also affected by the production rate of the decomposition product of NC. Thus, as the storage period of single base propellants lengthens, the reduction rate of the tranquillizer content increases. This paper presents a new methodology based on data mining and regression analysis for estimating the shelf-life of single base propellants using data from the ASRP to 105mm HE (KM1 and M1).

Combustion Characteristic Parameter Testing and Caculating of Single-Base Propellant

Combustion characteristics of single base propellant are tested with closed bomb. Combustion characteristic parameters are calculated through P-t curves. Gunpowder force f=974.30J·g-1, covolume α=1.111cm3·g-1. Laws of combustion rate are u=4.97×10-3P0.82 (charge density Δ1=0.10g·cm-3) and u=3.97×10-3P0.86(charge density Δ2=0.16g·cm-3).

Investigation on the foaming behaviors of NC-based gun propellants

Abstract To prepare the porous NC-based (nitrocellulose-based) gun propellants, the batch foaming process of using supercritical CO 2 as the physical blowing agent is used. The solubilities of CO 2 in the single-base propellants and TEGDN (trimethyleneglycol dinitrate) propellants are measured by the gravimetric method, and SEM (scanning electron microscope) is used to observe the morphology of foamed propellants. The result shows that a large amount of CO 2 could be dissolved in NC-based propellants. The experimental results also reveal that the energetic plasticizer TEGDN exerts an important influence on the pore structure. The triaxial tensile failure mechanism for solid-state nucleation is used to explain the nucleation of NC-based propellants in the solid state. Since some specific foaming behaviors of NC-based propellants can not be explained by the failure mechanism, a solid-state nucleation mechanism which revises the triaxial tensile failure mechanism is proposed and discussed.

Thermal Stability and Underwater Energy of Water Gel Explosive Using Expired Single-Base Propellants as Ingredients

A water gel explosive using expired single-base propellant grains as the ingredient was prepared by a simple process coupled with a new gelling system. The thermal stability and output energy of the explosive were studied using an accelerating rate calorimeter (ARC) and underwater blast test, respectively. The effects of oxygen balance, shape and size of the propellant, and storage time on the output energy of the explosive were investigated. It is shown that the initial decomposition temperature of the explosive was 418.24 K under adiabatic conditions. The underwater output energy increased with the increase in the oxygen balance of the explosive. The mass fraction and specific surface area of the propellant had effects on the output energy of the explosive. In addition, this water gel explosive was proven to have a stable storage performance after it had been stored for 6 months.

Thermal hazard research of smokeless fireworks

The problem of dealing with expired military propellant is paid wide attention throughout the world. Currently, destruction is adopted as the main disposal route; however, the process is cumbersome, dangerous, costly, and even more non-environment-friendly. As a result, it is absolutely necessary to find out an appropriate recycling method. Nowadays a feasible method, by which the expired military powders are used to make smokeless fireworks, has already been proposed. However, the security of expired military propellant is still making all those concerned anxious on account of the stabilizer’s volatilization during long-term storage. In this article, waste single base propellant (named powder 128, one of expired military propellants) and waste single base propellant/potassium perchlorate mixed powder are analyzed by differential scanning calorimeter (DSC) and accelerating rate calorimeter (ARC). The mixtures of these two are considered as the ideal raw materials of smokeless fireworks. DSC results show onset temperature, peak temperature, and normalized heat release of thermal decomposition under the condition of linear heating. Based on DSC data, activation energy and pre-exponential factor of the test samples are calculated according to Kissinger method, Ozawa method, and Friedman method. Furthermore, \( T_{D24} \) is derived by means of AKTS-Thermokinetics software using DSC data. ARC results reveal onset temperature, adiabatic temperature rise, self-heat rate, time to maximum rate and pressure–temperature profile. \( T_{D24} \), which can be applied for the evaluation of thermal and pressure hazards, can be obtained in two ways from the data measured by ARC. One is calculated directly from the experiment, and the other indirectly from the fit-calculations. Based on these results, the thermal hazards of these two mixtures were analyzed preliminarily.

Controlled expedient disposal of excess gun propellant

The expedient field disposal of excess gun propellants on the ground is an integral part of live-fire training in many countries. However, burning excess propellant in the field will leave significant quantities of energetic residues and heavy metals in the environment. Compounds such as dinitrotoluene and nitroglycerin and metals such as lead will leach into the soil column, eventually migrating to groundwater. Contamination of the environment will lead to high remediation costs and the possible loss of the training facility. After investigating the contamination at several propellant disposal sites, a portable propellant burn pan was developed and tested. The pan was transported to training sites where excess propellant was loaded and burned in a controlled manner. Up to 120kg of excess single-base propellant charges have been burned during two series of tests at a consumption rate of greater than 99.9%. Less than 0.03% of the energetic material was recovered outside the burn pan. Recovered lead is largely contained within the pan. The turnover rate for burns is 15min. The residues can be collected following cool-down for proper disposal.

Experiments on the Combustion Characteristics of Deterrent-Coated Propellants and Their Application in Traveling Charge Propulsion

The combustion characteristics of deterrent-coated propellants and their application in a 105 mm caliber gun are investigated experimentally. The mixture of deterrent-coated and conventional single base propellant particles are fired in a 100 ml closed bomb with loading densities of 0.1 g/cm3 and 0.2 g/cm3, respectively. The measured pressure time profiles indicate that the deterrent can retard the combustion of coated propellants, and the delays are related to the pressure and the thickness of the deterrent. The optimized deterrent-coated propellants are attached to the tailfin of a 105 mm caliber armor piercing projectile (APP) as traveling charge, and fired in a 105 mm caliber gun. The firing results indicate that the traveling charge of deterrent-coated propellants can improve the muzzle velocity of projectiles by 2.8% and 4.2% under maximum pressure of 330 Mpa and 400 Mpa, respectively. The pressure time curves measured in the chamber indicate that pressure plateau effects can be expected by the combustion delay of deterrent-coated propellants.

Study on the Performance of the Modified Single Base Gun Propellant

The modified single base gun propellant was prepared from single base propellant grain by impregnation with blasting oil, followed by deterring with deterrent in water medium. The concentration profile of function component in the propellant was studied by Fourier Transform Infrared (FTIR) Microspectroscopy. The combustion performance of the propellant was investigated by means of closed-bomb test and interior ballistic test. The barrel erosion was characterized by erosion tube test. It is found that the curve of nitroglycerine concentration is just like a parabola along the radius and the polymer ester concentration in the near surface of propellant decreases exponentially from the surface inwards. Compared with the single base gun propellant, the modified single base gun propellant burns more progressively and the value of Pr increases from 0.097 to 0.424. The interior ballistic performance for this propellant charge is improved obviously. The muzzle velocity increases by 5.0% from 886.6 m/s to 931.3 m/s. The modified single base gun propellant has the characteristic of low temperature sensitivity and the barrel erosion of this propellant decreases by 26.6% at least. The modified single base gun propellant has the advantages of higher muzzle velocity, higher combustion progressivity, low erosion and low temperature sensitivity.

Function Component Concentration Profile-The Key Factor for the Modified Single Base Gun Propellant

A new generation of gun propellant, named Modified Single Base Propellant (MSBP), was successfully studied recently. The MSBP was prepared from single base propellant grain by impregnation with blasting oil, followed by deterring with deterrent in water medium. The function components in this propellant were nitroglycerine (NG) and polymer ester (NA). The concentration profiles of them were studied by Fourier Transform Infrared (FTIR) Microspectroscopy. The combustion performance of this propellant was investigated by means of closed-bomb tests and interior ballistic tests. It is found that the concentration profile of the function component is the key factor in MSBP. The static combustion performance and the characteristic of the interior ballistic are dependent on the concentration profile of function component.

Effect of application of various ignition conditions in closed-vessel tests on burning rate calculation of a fine-grained propellant

The most widely used experimental method for determination of dynamic characteristics of gun propellant combustion is burning a specific amount of a propellant in a closed chamber (vessel) and measuring the resulting pressure versus time profile. The aim of this work is to conduct experimental investigations at different conditions of propellant ignition, which permit to verify the view on legitimacy of standard conditions of closed-vessel tests. This paper considers first of all the influence of conditions of propellant ignition during closed-vessel tests on possible deviations in determination of the burning rate. For this purpose, experimental tests of a fine-grained, single-base propellant are carried out in a conventional closed vessel and a micro-closed vessel, applying different ignition methods for the same loading density. The results of experimental tests and calculations show significant influence of the ignition system type used on determined values of the burning rate and other dynamic characteristics of propellant combustion, such as dynamic vivacity, absolute quickness, and relative quickness.

Prediction of In‐Service Time Period of Three Differently Stabilized Single Base Propellants

AbstractThree nitrocellulose‐based propellants for use in micro gas generators equipped with different stabilizing systems have been investigated to assess the stabilization capability with regard to in‐service time, whereby strong time–temperature profiles have been applied. The three stabilizing systems have been (i) 0.74 mass‐% diphenylamine (DPA) and 0.48 mass‐% Akardite II (Ak II); (ii) 1.25 mass‐% Ak II; (iii) 2.04 mass‐% Ak II. Several profiles were considered. Two simulate the heating at sun exposure in hot areas, others consider environmental temperatures in hot‐humid and hot‐dry areas. They were evaluated according to the load and finally one was chosen for the assessment. The contents of stabilizers were determined by high performance liquid chromatography after Soxhlet type extraction. To describe stabilizer consumption, the most suitable kinetic model was taken. Therewith a prediction was made using the chosen time–temperature profile named ‘Phoenix’, designed for temperatures at the steering wheel. The objective was to reach with this profile 15 years until the consumption of primary stabilizer content. This is conservative, because with the stabilizing action of the consecutive products of the stabilizers longer times are possible.