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Abstract  

Compatibility is an important safety aspect related to the production and storage of energetic materials. To test different combinations of materials a simple test method with clear criteria is advisable. At the last ESTAC the use of microcalorimetry and the vacuum stability test for the compatibility testing of propellants were presented. This paper presents DSC, DTA/TG and (pressure) vacuum stability test results for the same combination. For three polymers (PMMA, PVC and CA) the results for all tests are the same. Only Nylon-6/6 gives a variable result for the different test methods.

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Abstract  

Characterization of autocatalytic decomposition reactions is important for the safe handling and storage of energetic materials. Isothermal differential scanning calorimetry (DSC) has been widely used to detect autocatalytic decomposition of energetic materials. However, isothermal DSC tests are time consuming and the choice of experimental temperature is crucial. This paper shows that an automatic pressure tracking calorimeter (APTAC) can be a reliable and efficient screening tool for the identification of autocatalytic decomposition behavior of energetic materials. Hydroxylamine nitrate (HAN) is an important member of the hydroxylamine family. High concentrations of HAN are used as liquid propellants, and low concentrations of HAN are used primarily in the nuclear industry for decontamination of equipment. Because of its instability and autocatalytic decomposition behavior, HAN has been involved in several incidents. This paper presents calorimetric measurements for the thermal decomposition of 24 mass% HAN/water. APTAC heat-wait-search and heat-soak-search modes are used to characterize the thermal decomposition of HAN. By comparing the kinetic analysis for the two modes, it is concluded that HAN shows strong autocatalytic decomposition behavior. The most likely decomposition pathway of HAN is proposed to explain the observed autocatalytic behavior.

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Journal of Thermal Analysis and Calorimetry
Authors: Lin-Quan Liao, Hong-Jian Wei, Ji-Zhen Li, Xue-Zhong Fan, Ya Zheng, Yue-Ping Ji, Xiao-Long Fu, Ya-Jun Zhang, and Fang-Li Liu

characteristics. Therefore, compatibility of PNIMMO with energetic materials in propellants or explosives is most important aspects of PNIMMO in practical application. However, investigations on these two aspects are rarely reported. Therefore, this study

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Journal of Thermal Analysis and Calorimetry
Authors: Seied Mahdi Pourmortazavi, Mehdi Rahimi-Nasrabadi, Iraj Kohsari, and Seiedeh Somayyeh Hajimirsadeghi

Introduction KNF or potassium nitroform is a colorless to white crystal or powder. The crystals of this potassium salt are stable and used widely in formulations of energetic materials such as gunpowders, rocket propellants

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, a sample is blended with highly heat-conducting inert material in the ratio M / m ≈ 100, where m and M are weights of the sample and the diluent. In the “thermal dilution” method developed for the study of heterogeneous energetic materials, s

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Abstract  

Compatibility is an important property for energetic materials and their additives such as a casing material or a binder. If these substances are incompatible an extra risk is introduced in handling and storage of ammunition and explosives. As part of a co-operation program between the Dutch TNO-PML and the Polish MIAT several compatibility tests are performed and compared with each other. All tests are performed according to a NATO Standard in which several tests are described which can be used to determine the compatibility of an energetic material and an additive. These tests were performed on a huge set of energetic materials e.g. propellants (single and double base), explosives (RDX, PETN, HMX and TNT) and several additives like Teflon, polypropylene, self-burning case, inhibitors etc. The results of pressure vacuum stability tests, dynamic thermogravimetry measurements and differential scanning calorimetry tests with several combinations of energetic materials and additives used during the co-operation program are presented and discussed.

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Abstract  

A device of measuring the thermal conductivity of pellet of propellants and explosives has been constructed. A method and a calculation formula for determining the thermal conductivity of pellet of propellants and explosives under constant radial heat flow conditions by use of Joule effect is presented. Using this device and a microcalorimeter, type RD496-II, and two standard samples with known thermal conductivity, two instrument constant have been determined and the thermal conductivities of seven materials: plexiglass, teflon, DB propellant DB-2 (nitrocellulose(NC)/nitroglycerine(NG)/dinitrotoluene/dimethyl centralite/vaseline/PbO/CaCO3, 59.6/25/8.8/3/1.2/1.2/1.2), DB propellant SQ(NC/NG/diethyl phthalate(DEP)/binder, 59/29/7/5), DB propellant RHN-149 (NC/NG/triacetin (TA)/binder-I, 52/25/8/15), DB propellant RHN-190 (NC/NG/TA/ binder-II, 52/26/7/15), 2, 4, 6-trinitrotoluene (TNT) at 298 K are measured. The results show that (1) the reproducibility of measurement for the heat (q) retained in investigated system after cutting the Joule current and the amount of heat flux through the wall of the investigated cylinder (Q s) are less than 0.50% and within 0.10%, respectively; (2) the standard deviation of the thermal conductivity determined by using this method is less than 1.0%; (3) the values ofq, Q s and internal radius of the cylinder are three principal factors affecting the magnitude of the thermal conductivity of these materials.

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Abstract  

The heat of reaction of HTPB mixtures was measured by calorimetric method. The mixtures were prepared according to 'ruggedness testing [1]'. The effect of the factors was calculated and it was found that the quantity of the energetic materials in the mixture was the most effective factor in the mixing process and it had the greatest effect on the response.

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Up-scaling of dsc data of high energetic materials

Simulation of cook-off experiments

Journal of Thermal Analysis and Calorimetry
Authors: B. Roduit, Ch. Borgeat, B. Berger, P. Folly, H. Andres, U. Schädeli, and B. Vogelsanger

Abstract  

Differential scanning calorimetry (DSC) carried out with few heating rates was applied in the studies of the thermal properties of four energetic materials: EI propellant, high explosive PBXW-17, pyrotechnic mixtures with composition B/KNO3 (50:50) and B/KNO3 (30:70). DSC signals, after optimization of the baseline, were used for the calculation of the kinetic parameters (KP) of the decomposition process applying advanced kinetic software designed by AKTS. The determination of the kinetic parameters was based on the differential iso-conversional method of Friedman. The correctness of the estimation of KP was checked by the comparison of the experimental and predicted courses of the decomposition. The slow cook-off experiments of above mentioned energetic materials were carried out with a heating rate of 3.3C h–1. For the simulation of the experimental results, the heat balance based on the finite element analysis (FEA) was applied together with the advanced kinetic description of the reaction. The comparison of the experimental and simulated data indicates that applied procedure resulted in a very good prediction of the temperature of the ignition. Application of commonly used, simplified assumptions concerning the mechanism of the decomposition (such as 1st or n th order mechanisms) led to significantly worse prediction of the cook-off temperatures.

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Journal of Thermal Analysis and Calorimetry
Authors: B. Roduit, L. Xia, P. Folly, B. Berger, J. Mathieu, A. Sarbach, H. Andres, M. Ramin, B. Vogelsanger, D. Spitzer, H. Moulard, and D. Dilhan

Abstract  

Two small calibre and four medium calibre types of propellants were investigated non-isothermally (0.25–4K min−1) by differential scanning calorimetry (DSC) in the range of RT-260°C and isothermally (60–100°C) by heat flow calorimetry (HFC). The data obtained from both techniques were used for the calculation and comparison of the kinetic parameters of the decomposition process. The application of HFC allowed to determine the kinetic parameters of the very early stage of the reaction (reaction progress α below 0.02) what, in turn, made possible the precise prediction of the reaction progress under temperature mode corresponding to real atmospheric changes according to STANAG 2895. In addition, the kinetic parameters obtained from DSC data enabled determination of self-accelerating decomposition temperature (SADT) and comparison of the predicted ignition temperature during slow cook-off with the experimental results. The study contains also the results of the calculation of the time to maximum rate (TMRad) of the propellants under adiabatic conditions.

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