B2977 – Study on thermal properties and kinetics of benzoyl peroxide by ARC and C80 methods
Benzoyl peroxide (BPO) has been widely used in the industrial and food field, it is sensitive to shock, heat and friction, and causes thermal explosion incidents easily. Therefore, it is important to understand its thermal behaviors and kinetics for loss prevention and safety management. Two kinds of experimental methods (C80 calorimetry and accelerating rate calorimetry) were used to study the hazardous characteristics of BPO, and idea kinetic parameters, such as the pre-exponential factor and the activation energy were obtained. These results contribute to improve the safety in the reaction, transportation, and storage processes and help to the stability criterion of decomposition reaction of BPO.
B2663 – Study on thermal decomposition characteristics of AIBN
It is found that the results such as observed in the differential scanning calorimeter (DSC), which show the major thermal decomposition (TD) of a self-reactive material, lack the detail to reveal what happens at the initial stage of a reaction. The reaction at this stage is corresponding to the handling condition of storage or transportation, often possibly having the potential to be developed to a runaway reaction. This paper examined and compared the thermal behaviors of AIBN at various working conditions in calorimeters and Dewar vessels. The mechanism that affects the initial reaction and self-heating behavior of the given material was clarified. Near its onset decomposition temperature, physical processes, such as sublimation or melting interfered the initial reaction of AIBN. The mutuality of the physical effect and the chemical reaction made AIBN behave differently under different measuring conditions, and as the result, quasi-autocatalysis or TD possibly occurs in the same sample at the handling temperature range. The heat accumulation storage tests in two Dewar vessels presented completely different self-heating behaviors due to this mechanism and heat transfer capability of the vessels.
B2658 – Thermal behavior of 3,4,5-triamino-1,2,4-triazole dinitramide
The thermal decomposition behavior of 3,4,5-triamino-1,2,4-triazole dinitramide was measured using a C-500 type Calvet microcalorimeter at four different temperatures under atmospheric pressure. The apparent activation energy and pre-exponential factor of the exothermic decomposition reaction are 165.57 kJ mol-1 and 1018.04 s-1, respectively. The critical temperature of thermal explosion is 431.71 K. The entropy of activation (?S), enthalpy of activation (?H), and free energy of activation (?G) are 97.19 J mol-1 K-1, 161.90 kJ mol-1, and 118.98 kJ mol-1, respectively. The self-accelerating decomposition temperature (TSADT) is 422.28 K. The specific heat capacity of 3,4,5-triamino-1,2,4-triazole dinitramide was determined with a micro-DSC method and a theoretical calculation method. Specific heat capacity (J g-1 K-1) equation is Cp = 0.252 + 3.131 x 10-3 T (283.1 K
B2493 – Thermal decomposition of organic peroxide with metals using calorimeters
In this study, we evaluated the reactivity of organic peroxides with metals. The effect of the metals on the decomposition of organic peroxides was measured using a differential scanning calorimeter (DSC). Results of DSC measurements showed that some organic peroxides have high reactivity with a gold plated cell. Especially, hydroperoxides were decomposed at lower temperature using the gold plated cell when compared to other type of cells. In order to evaluate the effect of metals on the hydroperoxides, the decomposition characteristics of cumenhydroperoxide (CHP) with metal powders were studied using a C80 calorimeter and the products were analyzed by a gas chromatograph. These results indicated that the radical reaction of CHP was catalyzed by the gold and the autocatalytic reaction of CHP was catalyzed by stainless steel (SUS) and hastelloy c (HC).
B2492 – Effect of heating rate on the thermal behavior of nitrocellulose
In the previous study, it was observed that the stability of nitrocellulose (NC) cannot be determined by thermal analyses such as differential scanning calorimetry (DSC) at heating rates of 1–10 K/min. This was because the thermal curves of NC samples with different stabilities could not be distinguished from one another. In this study, we explain why such thermal analyses cannot be used to evaluate the thermal stability of NC and identify the conditions under which thermal analyses can be used for this purpose. We investigated the effect of heating rate on the
thermal behavior of pure NC and NC stabilized with diphenylamine (DPA) or akarditeII (AKII), which is a conventional stabilizer, by using the heat flux calorimeter (C80). At high heating rates (0.2–0.3 K/min), only single exothermic peak was observed in the thermal curves of both pure NC and NC/DPA and the thermal curve of pure NC was practically similar to that of NC/DPA. At low heating rate (0.02 K/min), two exothermic peaks were observed for both pure NC and NC/DPA. The heat amount of the first peak depended on the partial pressure of O2 in the atmosphere. The first peak in the thermal curve of NC/DPA was slightly suppressed as compared to that of pure NC. These results indicate that the stability of NC probably depends on the first exothermic peak that represents oxidation of NC by atmospheric O2. From this, on the thermal analyses at high heating rates, thermal curves of pure NC and NC/DPA could not be distinguished from one another. This is because the decomposition of NC itself occurs in the second exothermic peak before the oxidation of NC by atmospheric O2 in the first peak, which is attributed to the stability of NC. The results of the thermal analyses under isothermal conditions at 393 K in an O2 atmosphere revealed that the induction period of NC/DPA and NC/AKII was longer than that of pure NC. From these results, it is speculated that the stability of NC can be evaluated by thermal analyses carried out under O2-rich conditions at low heating rates.
B2491 – Effect of industrial water components on thermal stability of nitrocellulose
In order to prevent the spontaneous ignition of nitrocellulose (NC), NC is stabilized by washing with industrial water in its synthesis process. However, there is a possibility that the components in industrial water contribute to the thermal stability of NC. In this way, the purpose of this study is to clarify the effect of industrial water components on the thermal stability of NC. In experiments, a heat flux calorimeter was used to observe the thermal behavior of NC with the residue of vaporized industrial water. The induction period of heat release of NC with 2-mass% residues was approximately 2–5 h shorter than that of NC alone whose induction period was observed at 7 h. Those results indicate that the residue destabilized NC. On the other hand, when the additive amount of the residue was increased, the induction period gradually increased as well. Based upon these results, we assume that inorganic salts contributing to stabilizationand destabilization competitively coexist in the industrial water components. The same thermal analysis was performed onNC with CaCO3, CaSO4, CaCl, ZnSO4, NaCl, and
CuCl. Those salts are predicted to exist in the industrial water. In the results, the induction period of NC with 2-mass%CaCO3 was approximately 15-h longer than that of NC alone, while the induction period with the inorganic salts CaSO4, CaCl, ZnSO4, NaCl, and CuCl was 4–5-h shorter. Therefore, when the industrial water components accumulate in NC, the destabilization by inorganic salts such as CaSO4, CaCl, ZnSO4, NaCl, and CuCl and the stabilization by compounds such as CaCO3 are thought to countervail against each other.
B2408 – Thermal behavior of 3,4,5-triamino-1,2,4-triazole nitrate
The thermal decomposition behaviors of 3,4,5-triamino-1,2,4-triazole nitrate were studied using a C500 type Calvet Micro-calorimeter at four different heating rates. Its apparent activation energy and pre-exponential factor of exothermic decomposition reaction are 137.16 kJ mol?1 and 1010.03 s?1. The critical temperature of thermal explosion is 441.37 K. The entropy of activation ( S / = ), enthalpy of activation ( H / = ), and free energy of activation ( G / = ) of the decomposition reaction are?65.65 J mol?1 K?1, 132.97 kJ mol?1 and 166.35 kJ mol?1, respectively. The self-accelerating decomposition temperature (TSADT) is 429.56 K. The specific heat capacity was determined with a Micro-DSC method and a theoretical
calculation method. Specific heat capacity (J g?1 K?1) equation is Cp = 0.356 + 2.957×10?3T (283.1K< T < 353.2 K). The adiabatic time-to-explosion is calculated to be a certain value between 702.22 s and 712.22 s. The critical temperature of Hot-Spot initiation is 600.325 ?C, and the characteristic drop height of impact sensitivity (H50) is 27cm
B2369 – Thermal decomposition analysis of organic peroxides using model-free simulation
To understand better the thermal decomposition characteristics of organic peroxides, a C80 heat flux calorimeter was used and the decomposition pattern of cumene hydroperoxide and di-tert-butylperoxide were classified as auto-catalytic and nth order reaction, respectively. Based on the scanning results with the C80 at several differing rates of heating, the thermal decomposition behavior of organic peroxides under isothermal storage at lower temperature was simulated with a model-free simulation. Simulated results showed that the calculated conversion of cumene hydroperoxide as a function of time was in good agreement with experimental data obtained with the TAM-III high sensitivity thermal activity monitor.
B2367 – Thermal characteristics of lysine tri-isocyanate and its mixture with water
The thermal reactivity of lysine tri-isocyanate (LTI, 2-isocyanatoethyl-2,6-diisocyanato caproylate) and its mixture with1%waterwas investigated after the occurrence of a runaway reaction at a plant. By using a sensitive thermal calorimeter, C80, and an adiabatic calorimeter, ARC, an onset reaction of LTI was observed at 70–100 ?C and it became vigorous at 175–200 ?C. The reaction is considered as co-polymerization at this stage, which causes a second decomposition reaction at 200 ?C if the heat generation is accumulated in the vessel. On the other hand, the presence of water can catalyze LTI at much lower onset temperature and lead to a moderate reaction at 50 ?C since carbamine is produced and in turn it induces decarbonization of the LTI molecule with significant release of CO2 gas which was detected by a gas chromatography and an FT-IR gas
B2358 – Thermal characteristics and their relevance to spontaneous ignition of refuse plastics/paper fuel
Being used as a new type of solid fuel, refuse plastics/paper fuel (RPF) is made up of waste paper and a variety of plastics such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, etc. It is imperative to examine the thermal and self-heating behaviors of RPF because of the propensity of spontaneous ignition during its storage. RPF used in this study was sampled from a fire site. A thermogravimetry/differential thermal analysis (TG–DTA) test was carried out to screen its thermal behavior.
In comparison, more precise measurements for RPF were conducted in Calvet calorimeters (C 80 and MS80), in which heating rates were 0.1 and 0.02 C/min, respectively. Isothermal measurement was performed in a thermal activity monitor (TAM) to examine the reaction at 50 C. Spontaneous ignition tests were performed in a wire mesh cube at certain constant environmental temperatures and a spontaneous ignition tester (SIT) under an adiabatic condition. Results showed that measurement conditions, such as heating rate, sample size, sensitivity of calorimetry, and adiabatic condition in storage significantly affect the thermal behaviors of RPF. The TG–DTA curves showed that the visible weight loss and exothermic reaction of RPF occurred at a temperature above 170 C. This is caused by the oxidation and degradation of the components in the RPF. Ignition of RPF by self-heating was found at the corresponding temperature in the wire mesh cube. Whereas in C 80 several endothermic peaks, coming from the melting of plastics, were observed in the range of 120–170 C ahead of major exothermic peaks. In MS 80, the thermal properties related to different phases of physical and chemical changes were seen more distinctly in which the start of exothermic process shifted to lower temperature of about 134 C. The relevant spontaneous ignition was confirmed at 118 C by the SIT test. Kinetics of the reaction was analyzed from the above data and the correlation of the critical temperature and the size of pile-up were predicted based on the Frank–Kamenetskii thermal explosion theory. It showed that the spontaneous ignition may start at a lower temperature than the normal expected temperature of 170 C. The reaction at the lower temperature is usually suppressed by the endothermic effect of the melting of plastics; on the other hand, if the heat conductivity condition becomes worse in the RPF storage, the initial exothermic reaction can potentially support self-heating of the volume to the final occurrence of the ignition.
B2356 – Study on the influence of moisture content on thermal stability of propellant
This paper studies the influence of moisture content on the thermal stabilities of double-base propellant and multi-nitro ester propellant. The thermal behaviors and chemical kinetic parameters of the above two propellants and their mixtures with water were analyzed by using a CALVET heat flux calorimeter, C80. The thermal decomposition mechanisms of these two propellants withwaterwere conjectured based on the tests. And then, the self-accelerating decomposition temperatures (SADT) of these two propellants and their mixtures with water were calculated and compared according to the kinetic parameters and Semenov model. The results show that the thermal decomposition mechanism of double-base propellant with water may be changing with the varying moisture content by transferring hydrogen proton (H+). However, the thermal decomposition mechanism of multi-nitro ester propellant with water may be unchanging due to the excess of formaldehyde (HCHO). Water plays the external physical factor on the thermal decomposition of multi-nitro ester propellant, and it plays both the physical and the chemical
factors on the thermal decomposition of double-base propellant. The SADTs of their mixtures with water are much lower than that of pure propellants, and keep decreasing with the increasing of moisture content.
B2355 – Study on the contamination of chlorides in ammonium nitrate
A terrible mass explosion of about 400 tons of ammonium nitrate (AN) occurred in Toulouse AZF plant on 21 September 2001. According to the review of the accidental
investigation, there may be resources of impurities to be introduced into the mass of ammonium nitrate. In this study, several chloride salts, including ammonium
chloride, barium chloride, calcium chloride, sodium chloride and potassium chloride, were added into ammonium nitrate at concentrations of 0.05, 0.1, 0.5, 1 and 2%, respectively. A
differential scanning calorimeter and a heat flux calorimeter C80 with higher sensitivity were used to measure the decomposition of ammonium nitrate and its mixtures with these
impurities. All the results demonstrated that the addition of a small account of chloride gives rise to a significant decrease in the initial decomposition temperature of AN by
nearly 100°C and the magnification of heat release from the reaction. The intensity of the decomposition of ammonium nitrate with and without impurities was also examined by
a modified pressure vessel test (MCPVT), in which the rate of pressure rise of AN in the presence of chlorides in the MCPVT was multiple. It implied that, with the addition of
impurities, the decomposition of AN is more intense and occurs at lower temperatures. However, in the BAM 50/60 steel tube test, no detonation was observed for either pure
AN or contaminated AN under the test conditions. However a detonation is predicted under more severe conditions
B2354 – Catalytic effects of inorganic acids on the decomposition of ammonium nitrate
In order to evaluate the catalytic effects of inorganic acids on the decomposition of ammonium nitrate (AN), the heat releases of decomposition
or reaction of pure AN and its mixtures with inorganic acids were analyzed by a heat flux calorimeter C80. Through the experiments,
the different reaction mechanisms of AN and its mixtures were analyzed. The chemical reaction kinetic parameters such as reaction order,
activation energy and frequency factor were calculated with the C80 experimental results for different samples. Based on these parameters
and the thermal runaway models (Semenov and Frank-Kamenestkii model), the self-accelerating decomposition temperatures (SADTs) of
AN and its mixtures were calculated and compared. The results show that the mixtures of AN with acid are more unsteady than pure AN. The
AN decomposition reaction is catalyzed by acid. The calculated SADTs of AN mixtures with acid are much lower than that of pure AN
B2299 – The construction and evaluation of a high pressure manifold and vessels for a Calvet type microcalorimeter
A Setaram C-80 calorimeter has been modified in order to measure the heat flow of energetic materials at pressures up to
69MPa. A manifold and sample cells capable of operating at high pressure were designed, constructed and evaluated. This
paper will describe, in detail, the high pressure manifold construction, safety assessment and calibration. As well, the results
for initial trials with ammonium nitrate (AN), and pentaerythritol tetranitrate (PETN) at various pressures and heating rates
will be discussed.
B2289 – Decomposition of methyl ethyl ketone peroxide and mixtures with sulfuric acid
The fact that an explosion starts at a lower ambient temperature when methyl ethyl ketone peroxide (MEKPO) is not sufficiently
neutralized, is demonstrated with a highly sensitive small-scale calorimeter (C80D). The data indicate that MEKPO might undergo
acid and redox decompositions in addition to thermal decomposition in the accidental scenario. Meanwhile, experimental results
of modified closed pressure vessel tests (MCPVT) suggest that the decomposition is much more active for MEKPO in the presence
of sulfuric acid. Under such conditions, the maximum pressures and the maximum rates of pressure rise are significantly higher
than those of pure MEKPO.
B2142 – Thermal stability of organic peroxide with metals
In this study, we evaluated reactivity of organic peroxides with metals. The effect of useful metals
for decomposition of organic peroxides was measured by Differential Scanning Calorimeter (DSC).
Results of DSC measurement with several kinds of sample cells showed that some of organic peroxides
have high reactivity with gold plated cell. Hydroperoxides were decomposed lower temperature
by using gold plated cell than other cells. Only hydroperoxides showed such the effect of
gold. For example, the onset temperature of t-Butyl hydroperoxide (TBHP) got from measurement
using gold plated cell was about 50 K lower than stainless steel cell. In order to the effect of gold for
hydroperoxides, the decomposition characteristics of Cumenhydroperoxide (CHP) with metal
powder were studied by C80 calorimeter and the decomposed compounds were analyzed using
GC and GC/MS. The result of thermal decomposition of CHP with gold powder shows that
gold is catalysis of radical reaction.
B2140 – Thermal hazards evaluation of sodium dithionite by micro-calorimeter
Sodium dithionite has caused a lot of fire accidents in China, which was taken more consideration at
present. In order to evaluate its thermal hazards, the heat releases of decomposition or reaction of
pure sodium dithionite and its mixtures with different mass of water were analyzed by a heat flux
calorimeter C80. The chemical reaction kinetic parameters such as activation energy and pre-frequency
factor were calculated with the C80 experimental results for different samples. Based on
these parameters and the thermal runaway models, the self-accelerating decomposition temperatures
(SADTs) of sodium dithionite and its mixtures with different mass of water were calculated
and compared. The results show that the mixtures of sodium dithionite with water are more
unsteady than pure sodium dithionite, and the calculated SADTs of sodium dithionite mixtures
with water are much lower than that of pure sodium dithionite. The results indicate that the
wetted sodium dithionite starts self heating reaction at lower temperature than that of pure
sodium dithionite, which accelerate the process of self-heating fire.
B2061 – Thermal Conductivity Testing of Minimal Volumes of Energetic Powders
Safety constraints have traditionally presented researchers with challenges in testing the thermal conductivity of energetic powdered materials. Minimal volumes of energetic powders can now be tested with the modified transient plane source technique. The newly modified sensor design further reduces the possibility of impact, friction and electrostatic discharge (ESD) hazards. This paper will present results generated in testing ammonium perchlorate (AP).
B1775 – Thermal decomposition kinetic of liquid organic peroxides
This study demonstrates the application of isothermal calorimeter for investigating the thermal decomposition of several liquid organic
peroxides, such as t-Butyl peroxy acetate (TBPA), Di-tert butyl peroxide (DTBP), and Cumene hydroperoxide (CHP). The decomposition
mechanism and kinetic can be identified from case to case. TBPA and DTBP undergo first order reaction, whereas CHP occurs autocatalysis.
Accurate kinetic can be assessed on the basis of discerning these various schemes of given samples. Consequently, the thermal runaway or
reactive hazards potential of organic peroxides can be determined, for instance as a self accelerating decomposition temperature (SADT).
B1706 – Catalytic effects of inorganic acids on the decomposition of ammonium nitrate
In order to evaluate the catalytic effects of inorganic acids on the decomposition of ammonium nitrate (AN), the heat releases of decomposition or reaction of pure AN and its mixtures with inorganic acids were analyzed by a heat flux calorimeter C80. Thro
B1636 – Thermal study of HNIW (CL-20)
The thermal properties of the energetic material 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaaza-tetracyclo-[5.5.0.05,9.03,11]-dodecane (HNIW), also known as CL-20, have been investigated by DSC, TG, ARC, HFC and simultaneous TG-DTA-FTIR-MS.
The solid-solid phase transitions and the reversibility of these phase transitions were explored using DSC. A heating rate study was performed and the DSC traces show the possibility of a multi-step thermal decomposition of CL-20. The enthalpies of reaction and onset temperatures were determined for various heating rates. The kinetic parameters were found by means of the ASTM E698 method and were verified by ageing experiments. A model-free kinetic (MFK) analysis was performed on the DSC heating rate results.
TG experiments were conducted to investigate the effects of various heating rates on the mass loss of CL-20 and its onset temperature. The TG results were analyzed using MFK and ASTM E1641 methods.
ARC measurements were performed to investigate the thermal stability of CL-20. The thermal behaviour of CL-20 at various pressures of argon was studied by heat flux calorimetry (HFC).
The gaseous products from the decomposition of CL-20 were determined by simultaneous TG-DTA-FTIR-MS experiments in air and in helium. The thermal stability at different isothermal temperatures (190, 195, 200 and 205°C) was studied, using the same technique.
B1627 – Study on the spontaneous ignition mechanism of nitric esters (III)
The spontaneous ignition mechanism of three types of smokeless powders such as cellulose nitrate/potassium sulfate (SB), cellulose nitrate/glycerin trinitrate/potassium sulfate (DB), and cellulose nitrate/glycerin trinitrate/nitroguanidine/potassium sulfate (TB) were analyzed in terms of the thermal behavior and the pressure change during the isothermal storage at 393 K in various gases. The heat release of SB and DB was suppressed in the atmosphere without O2 and even in 4.5 vol.% NO2/N2. However, in 4.7 vol.% NO2/air, the exothermic reaction was accelerated compared to that in dry air. In addition, the total pressure decreased during the storage in the presence of O2. This nature of the behavior of SB and DB indicated that autoxidation, which was propagation with O2 and radical species derived from NC, was involved in the exothermic reaction. And, NO2 contributed not to the autoxidation but to the initiation process before the autoxidation occurred. On the other hand, the exothermic reaction of TB might be different from that of SB and DB because TB released the reaction heat in no O2 atmosphere such as 4.5 vol.% NO2/N2. TB would react with NO2 without O2 and release the reaction heat when NO2 was excessively present in the system. This specific nature would be due to the presence of 50 wt.% of nitroguanidine which was not nitric ester.
B1626 – Study on the spontaneous ignition mechanism of nitric esters (II)
The thermal behavior of cellulose nitrate (NC) with diphenyl amine (DPA) or a phenol-based oxidation inhibitor (AO80) was investigated in order to estimate the effect as a stabilizer in a smokeless powder. During the isothermal storage at 393 K, both stabilizers decreased the amount of the reaction heat of NC, and lengthened the induction period of the exothermic reaction. Those effects might indicate that both stabilizers were capable of suppressing the spontaneous ignition. However, the effects of DPA and AO80 on the isothermal storage of NC were different. Under the storage in O2, DPA showed larger effect on the induction period but less effect on the released heat reduction than AO80 did. Those differences might be understood as follows: DPA mainly prevented the reaction before the autoxidation by trapping NO2, while AO80 mainly prevented the autoxidation of NC by trapping ROO.
B1625 – Study on the spontaneous ignition mechanism of nitric esters (I)
The spontaneous ignition mechanism of cellulose nitrate (NC) was analyzed in terms of the pressure change and the thermal behavior during isothermal storage at 393 K. During storage of the NC, atmospheric O2 was consumed during an exothermic reaction. The heat release behavior as well as the O2 decreasing behavior could be fitted to a first-order reaction. The rate constant (K) and the induction period (tindc) for the heat release behavior almost coincided with those for the O2 decreasing behavior (O2 decreasing behavior: K = 7.7 x 10^(-5) s-1, tindc = 10 h; heat release behavior: K = 8.1 x 10^(-5) s-1, tindc = 9.2 h). The reaction heat did not increase even if the initial amount of NC increased under a limited O2 condition. These results would suggest that NC released reaction heat due to autoxidation which was propagation involving O2 and radical species generated from NC. Even in a 4.7 vol.% NO2/air atmosphere, the amount of reaction heat did not significantly change from those in dry air. The reaction order was also not affected by the partial pressure of NO2. On the one hand, the K was slightly higher, and the tindc was shorter in the 4.7 vol.% NO2/air (K = 1.8 x 10^(-4) s-1; tindc = 3.4 h) than those in dry air. These results would indicate that NC accumulated reaction heat due to autoxidation by atmospheric O2, and NO2 contributed to the initiation process before the autoxidation occurred.
B1222 – Prediction and evaluation of the reactivity of self-reactive substances using microcalorimetries.
To evaluate the thermal hazard of self-reactive substances in chemical processes, the time to maximum rate (TMR) of autocatalytic decomposition reaction of cumenehydroperoxide (CHP) was determined by calculations based on the results of isothermal measurement using DSC and heat conduction calorimeter. In addition, the factors affecting the calculated results were investigated. It was found that the TMR is affected by the catalytic action of the sample vessel metal. When this effect is taken into account in analyzing the experimental result, the predicted TMR shows a good agreement with the value determined using the adiabatic reaction calorimeter. The present study clarified that the proposed technique would enable the appropriate evaluation of thermal hazard of an autocatalytic reaction.
B1161 – Kinetic studies of thermal decomposition of propellants
B1154 – A new type of high pressure system for a Tian-Calvet calorimeter
A Tian-Calvet heat flux calorimeter has been modified for use with high pressures in measurements of thermal hazards of materials. The system comprising a specially designed high pressure vessel and an associated manifold is described. With this system, comparative measurements using both standard and high pressure vessels can be made, different materials and/or liners can be used for the high pressure vessel and an assessment of the influence of the gaseous environment on thermal behaviour can be made. Calibration was carried out in the range 25 to 300°C at different pressures and heating rates, using sapphire and the calibration results were verified with benzoic acid, both reference grade materials. With the new vessel, pressures up to about 70 MPa can be used or recorded during the thermal decomposition of energetic materials.
The reproducibility of the baseline, as illustrated by standard error results, was about 0.02% compared with 0.13% for the standard vessel, over the entire temperature range. The corresponding results for the baseline of the pressure vessel at 5.5 MPa (in air and Ar) and in a calibration experiment with sapphire were 0.08%.
Experimental data obtained for ammonium nitrate and 2,3-dimethyl-2,3-dinitrobutane in the standard and pressure vessels are compared and discussed. The effect of pressure and the nature of the gaseous environment (inert or oxidizing) on the results for these two materials will be described.
B1061 – Thermochemical and thermodynamic properties of M(NTO)n and M(NTO)n.mH2O.
The enthalpies of solution in water of M(NTO),-mH20 (M = metal, NTO = 3-nitro-1,2,4-
triazol-5-one; M = Na, n = m = 1; M = La, Ce, Pr, Eu, Sin, n = 3, m = 7; M = Y, Yb, n = 3, m = 6;
M=Dy, Tb, n=3, m=5; M=Nd, n=3, m=8; M=Co, Mn, Mg, n=2, m=8) have been
measured calorimetrically at 298.15 K. By means of a thermochemical calculation, the standard
enthalpies of formation for the above fourteen metal salt hydrates of NTO were obtained. With
the help of the above-mentioned data, literature data and Kapustinskii's equation, the lattice
energies, lattice enthalpies and standard enthalpies of formation for twenty M(NTO), and the
lattice energies, lattice enthalpies and standard enthalpies of dehydration were estimated for
B1052 – Heat-flux calorimetric method for the determination of spontaneous oxidative heat rate of active carbon containing oxidizable/volatile organics
Carbon beds containing organics, in contact with air, exhibit potential for thermal runaway. To accurately define the spontaneous oxidative thermokinetics, appropriate calorimetric techniques are required. A stopped-flow heat-flux calorimetry for oxidative heat-rate measurement is presented in conjunction with the results generated by accelerating rate calorimetry. The stopped-flow method eliminates many experimental uncertainties encountered with the conventional continuous gassparging method, and generates accurate and reproducible heat-rate data in a single test run. This technique is particularly useful in solid oxidation systems containing volatile organics.
B0983 – The application of microcalorimetry in the compatibility test for pyrotechnics
This paper describes the characteristics of the microcalorimeter and method used in compatibility tests for pyrotechnics. The results are compared with those of the traditional VST method. To demonstrate the accuracy of the results, we analysed the surface structure of the tested materials using SEM. The testing conditions using the microcalorimetry method approach the actual storage conditions more than in the other methods, and the conclusion based on microcalorimetry is more reliable than that of traditional methods.
B0977 – Evaluation of thermal stability of energetic materials
B0943 – Enthalpy of thermal decomposition of pyrite concentrate
The enthalpy of thermal decomposition of pyrite concentrate (PC) in an inert atmosphere was measured by differential thermal analysis (DTA) and differential scanning calorimetry (DSC). The decomposition is a two-stage process and the enthalpy values of the overall process determined by the two methods are very close to each other: DTA, ?H = 72.2 kJ per mol FeS2; DSC, ?H = 70.1 kJ per mol FeS2.These values are quite different from the calculated standard enthalpy of FeS2 decomposition at 1000 K, ?H = 154.0 kJ per mol FeS2, and the enthalpy calculated from the Clausius-Clapeyron equation with dissociation pressure data for FeS2, ?H = 181.9 kJ per mol FeS2.
B0853 – The thermal decomposition of azide polymers containing ferruginous compounds
Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), as well as dynamic exothermic deflagration and vacuum stability tests, were employed to investigate the thermal characteristics of azide polymer binder systems in the presence o
B0816 – Principle of monitoring of propulsive powders in France
B0800 – Application of isothermal calorimetry and UV spectroscopy for stability monitoring of pentaerythritol tetranitrate
Thermal stabilities for three pentaerythritol tetranitrate (PETN) samples with variable surface areas were monitored by isothermal calorimetry and UV spectroscopy over the range 363-408 K. Isothermal induction times measured with constant volume calorimetry under an air atmosphere, and NO evolution rates monitored by UV absorbance at 213 nm under vacuum correlated with the PETN surface area at temperatures equal or exceeding 383 K. Rate data measured at 383 K are in accord with predictions based on detailed kinetic modeling. Below 383 K, NO evolution data suggested that additional geometric factors may be significant in controlling PETN stability. Mechanisms for the influence of surface area upon the rate-determining step are addressed.
B0703 – Solid-state decomposition kinetics of pentaerythritol tetranitrate.
B0644 – Application of rigorous nonlinear regression for the analysis of complex isothermal DSC reactivity curves
B0574 – The thermal behaviors of 1,1′-dimethyl-5,5′-azotetrazole and its monohydrate
B0484 – Principe de la surveillance des poudres propulsives en France
B0483 – Modélisation du phénomène d’auto-inflammation des propergols et exemples d’application
B0433 – Puissances calorifiques dégagées par les poudres homogènes : Résultats de mesures effectuées sur divers lots de propergols neufs et anciens, par microcalorimétrie isotherme
A1056 – Hydrocalumite-type materials: 1. Interest in hazardous waste immobilization
This study investigated the incorporation of Cr, V and Si oxoanions into hydrocalumite. Hydrocalumite together with ettringite form during the
hydration of Portland cement and the use of these materials in hazardous waste immobilization is of current concern. The anion uptake was
examined in terms of the structural characteristics by means of thermogravimetric analysis, infrared spectroscopy, X-ray diffraction (XRD) and
in situ high temperature X-ray diffraction (HTXRD). The syntheses were carried out by coprecipitation or exchange reaction. The short
interlamellar distances observed for Ca2Al-V2O7 and Ca2Al-SiO4 phases, 7.90 and 10.93 Å , respectively, are explained by a grafting process onto
the hydroxide layers. The good crystallinity of Ca2Al-CrO4 allowed the refinement of the cell parameters in the P-3 space group with
a=5.7507(3) Å and c=20.164(2). A structural model is proposed with CrO4 species close to the seventh coordination position of Ca atoms. In
situ HTXRD measurements in the temperature range 25-350°C reveal different thermal behaviors depending on the oxoanion. At low
temperature, a dehydration-hydration process partly reversible was observed for Ca2Al-V2O7 and Ca2Al-CrO4 phases, between 100-200 and
50-120°C, respectively. At higher temperature, strong interlayer contractions were observed due to a pillaring process: ?d/d= -13% for
Ca2Al-V2O7 at 200°C, ?d/d= -32% for Ca2Al-CrO4 at 250°C and ?d/d= -35% for Ca2Al-SiO4 at 135°C.
A0869 – Kinetics of thermal decomposition of sodium methoxide and ethoxide
Sodium methoxide and sodium ethoxide were synthesized. Their thermal decomposition and reaction kinetics were investigated
under non-isothermal and isothermal conditions. Non-isothermal experiments were carried out at different linear
heating rates. Kinetics of decomposition in each run was evaluated from the dynamic TGA and MS data obtained from
thermogravimetric analyzer (TGA) coupled with mass spectrometer based evolved gas analyzer (EGA-MS). The activation
energies derived from isothermal experiments by Arrhenius plot were 187.81 ± 11.22 and 150.84 ± 5.32 kJ mol-1 for
sodium methoxide and sodium ethoxide, respectively, which agree well with the values from non-isothermal method.
The evolved gases were found to be a mixture of saturated and unsaturated hydrocarbons. XRD, IR, AES, CHNS analyzer
and volumetric estimation were employed to characterize the decomposition residue and identified as a mixture of sodium
carbonate, sodium hydroxide and amorphous carbon. The probable mechanism and kinetics of decomposition of sodium
alkoxides described in this paper are reported for the first time.
A0497 – A study on the thermal decomposition behavior of derivatives of 1,5-diamino-1H-tetrazole (DAT): A new family of energetic heterocyclic-based salts
The thermal decomposition of the highly energetic 1,5-diamino-4-methyl-1H-tetrazolium nitrate (2b), 1,5-diamino-4-methyl-1H-tetrazolium dinitramide (2c) and 1,5-diamino-4-methyl-1H-tetrazolium azide (2d) were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Mass spectrometry and IR spectroscopy were used to identify the gaseous products. Decomposition appears in the cases of 2c and 2d to be initiated by a proton transfer to form the corresponding acid HN3 and HN3O4 whereas in the case of 2b a methyl group transfer to MeONO2 is observed as initial process. The gaseous products after the exothermic decomposition are comparable and are in agreement of the possible decomposition pathways discussed for the corresponding compounds. For all processes, possible decomposition schemes are presented. The decomposition temperatures of 2b and 2c are significantly higher than that of 2d and were supported by evaluation the values of the activation energy according the method of Ozawa and Kissinger.