The Self-accelerating Decomposition Temperature Research Articles

Investigation of Thermal Decomposition Kinetics of Some RDX Based Material

The aim of the current study is to compare thermal decomposition kinetics of three 1, 3, 5-trinitro-1, 3, 5-triazinane (RDX) based explosives, containing A4, H6, and PBXW-108 using TGA/DSC experimental techniques and analytical methods. The experimental part of the study performed non-isothermally at 1, 2, 5, 10, 15, and 20‌ °C min-1 heating rates. A complementary approach which is a combination of model free isoconversional methods and model fitting methods was carried out to achieve more accurate results for the kinetic parameters. Moreover, Arrhenius parameters were determined by non-isoconversional Kissinger’s method. The values of the self-accelerating decomposition temperature (TSADT)and the critical ignition temperature (Tb) were also calculated. The results indicated that PBXW-108, a plastic bonded explosive, in comparison to H6 and A4 has the highest pre-exponential factor and activation energy of decomposition. Moreover, TSADT and Tb of PBXW-108 are higher than those of A4 and H6. Therefore, PBXW-108 can be introduced as a safer alternative to traditional A4 and H6 explosives. According to the obtained results, the contracting area model (R2) is the best choice for describing both PBXW-108 and H6 decompositions, while the F1/3 model is the suitable one for A4.

Synthesis, Thermal Behavior and Energy Performance of Nitroguanidyl‐Functionalized Energetic Materials

AbstractSix nitroguanidyl‐functionalized nitrogen‐rich compounds were synthesized and characterized by EA, FT‐IR, and NMR. In addition, the crystal structures of ANPTz, CABNG, and FANG were further determined by X‐ray single‐crystal diffractometer. The thermal decomposition behaviours were studied by the DSC‐TG‐FTIR‐MS coupling technique and the results showed that all the compounds had good thermal stability, among which ANPTz had the best thermal stability (Td=211.03 °C). Also, HCN, CO2, H2O, and NO2 were released during thermal decomposition process. The self‐accelerating decomposition temperature (TSADT) and thermal explosion critical temperature (Tb) were calculated to evaluate thermal safety, and the relative order was as follows: FANG (TSADT=198.68 °C, Tb=209.97 °C)> ANPTz (TSADT=194.12 °C, Tb=208.63 °C)> BANTz (TSADT=182.52 °C, Tb=207.54 °C)> AANG (TSADT=180.04 °C, Tb=188.35 °C)> CABNG (TSADT=176.80 °C, Tb=187.32 °C)> MABNG (TSADT=173.61 °C, Tb=184.29 °C). The results indicated that FANG had the acceptable sensitivity (IS=7.84 J), good detonation performance (D=8551 m⋅s−1, P=32.33 GPa), and the significant catalytic effect (the decomposition temperature of RDX decreased by 8.31 °C).

Thermal Behavior and Detonation Characterization of 3,3‐Dinitroazetidinium Salicylate

AbstractThe thermal behavior of 3,3‐dinitroazetidinium salicylate (DNAZ ⋅ SA) was studied under a non‐isothermal condition by DSC and TG/DTG methods. The intense exothermic decomposition processes of DSC curves were analyzed to obtain its kinetic parameters. The self‐accelerating decomposition temperature (TSADT), thermal ignition temperature (TTIT), and critical temperatures of thermal explosion (Tb) were obtained to evaluate its thermal stability and safety. The DFT was used to calculate its band structure; the energy gap was obtained to evaluate its impact insensitivity. Its detonation velocity (D) and detonation pressure (P) were estimated using the nitrogen equivalent equation according to the experimental density. The above results of DNAZ ⋅ SA were compared with those of 3,3‐dinitroazetidinium 3,5‐dinitrosalicylate (DNAZ ⋅ DNS), and the effect of nitro group on them were discussed, which results indicate that the nitro group increases the safety and energy simultaneously.

Preparation, characterization of RDX/GAP nanocomposites, and study on the thermal decomposition behavior

ABSTRACT1, 3, 5-trinitro-1, 3, 5-triazinane/Glycidylazide polymer (RDX/GAP) energetic nanocomposites were fabricated via a facile sol-gel method. Morphologies and structure characterization of RDX/GAP energetic nanocomposites were studied by scanning electron microscopy (SEM), Raman and Fourier-transform infrared spectroscopy (FT-IR). SEM images indicated the sizes of RDX particles in RDX/GAP nanocomposites were in nanoscale. FT-IR spectra of RDX/GAP nanocomposites showed the conjunct characteristics of RDX and GAP, implying RDX particles were trapped in GAP gel matrix. Raman detection revealed the crystal form of RDX maintained original α-form during sol-gel process. The thermal kinetics and thermodynamics of RDX/GAP energetic nanocomposites were investigated by differential thermal analyzer (DTA) under various heating rates (5, 10, 15, and 20°C min−1). The kinetic and thermodynamic parameters of the energetic nanocomposites, such as activation energy (Ea), activation enthalpy (ΔH≠), activation entropy (ΔS≠), and activation Gibbs free energy of (ΔG≠) were obtained. The activation energies of RDX/GAP nanocomposites were lower than those of raw RDX and GAP-RDX mechanical mixtures, indicating RDX/GAP nanocomposites presented high thermolysis activities. The thermodynamic parameters presented a rising trend when the contents of RDX increase. The critical temperature of thermal explosion (Tb) and the self-accelerating decomposition temperature (TSADT) based on the activation energy were also obtained.

Synthesis and Thermal behaviors of 1, 8-Dihydroxy-4, 5-Dinitroanthraquinone Nickel Salt

A novel energetic combustion catalyst, 1, 8-dihydroxy-4, 5-dinitroanthraquinone nickel salt (DHDNENi), was firstly synthesized by the process of metathesis reaction in a yield of 91%, and its structure was characterized by IR, element analysis, thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). The thermal behavior and non-isothermal decomposition reaction kinetics of DHDNENi were studied by means of different heating rate differential scanning calorimetry (DSC). The kinetic equation of major exothermic decomposition reaction for DHDNENi is obtained. The self-accelerating decomposition temperature (TSADT) and critical temperature of thermal explosion (Tb) are 574.4K and 593.4K, respectively. The thermal stability of DHDNENi is good.

Catalytic effect of lead oxide nano- and microparticles on thermal decomposition kinetics of energetic compositions containing TEGDN/NC/DAG

The catalytic effect of lead oxide nano- and microparticles (PbO) on the thermal behavior and decomposition kinetics of energetic formulations composed of nitrocellulose (NC), triethyleneglycol dinitrate (TEGDN) and diaminoglyoxime (DAG) was investigated by simultaneous thermogravimetric analysis and differential scanning calorimetry. The results show that lead oxide nano- and microparticles could significantly alter thermal pattern of the studied energetic compositions. The effect of lead oxide content on thermal behavior of energetic compositions was also studied, and the results revealed that addition of different amounts of lead oxide caused to shift in the DSC peaks. Moreover, the catalyst decreases activation energy of the decomposition stage of energetic composition at about 20–40 kJ mol−1. However, the catalyst enhances decomposition temperature of TEGDN/NC/DAG energetic compositions. By the aid of DSC data resulted by non-isothermal methods, the thermokinetic parameters such as activation energy (E a), frequency factor (A), the critical ignition temperature of thermal explosion, the self-accelerating decomposition temperature (T SADT) and also thermodynamic parameters of the studied energetic compositions were calculated and compared.

Thermal Behavior and Specific Heat Capacity of 1‐t‐Butyl‐3,3‐dinitroazetidinium Perchlorate

Abstract1‐t‐Butyl‐3,3‐dinitroazetidinium perchlorate (TDNAZ ⋅ HClO4) was synthesized, DSC and TG/DTG methods were used to study the thermal behavior of TDNAZ⋅HClO4 under a non–isothermal condition. The intense exothermic decomposition process of DSC curves were analyzed to obtain its kinetic parameters. Continuous specific heat capacity (Cp) mode of micro–calorimeter was used to determine its Cp, its specific molar heat capacity (Cp,m) was 365.70 J mol−1 K−1 at 298.15 K. The self‐accelerating decomposition temperature (TSADT), thermal ignition temperature (TTIT), and critical temperature of thermal explosion (Tb) were obtained to evaluate its thermal stability and safety. The above results of TDNAZ ⋅ HClO4 were compared with those of 3,3‐dinitroazetidinium perchlorate (DNAZ ⋅ HClO4), and the effect of tert‐butyl group on them was discussed.

Crystal Structure, Thermal Behavior and Detonation Characterization of Bis(3,3‐dinitroazetidin‐1‐yl)methane

AbstractBis(3,3‐dinitroazetidin‐1‐yl)methane (BDNAZM) was synthesized and the crystal structure was determined by a X‐ray diffraction. It belongs to monoclinic system with space group P21/n. Its thermal behavior and non‐isothermal decomposition kinetics were studied with DSC and TG/DTG methods. The self‐accelerating decomposition temperature (TSADT), thermal ignition temperature (TTIT), and critical temperature of thermal explosion (Tb) are 141.06 °C, 154.15 °C and 160.62 °C, respectively. BDNAZM has a low melting point (86.82 °C), and it has higher detonation velocity (7217 ms−1) and detonation pressure (22.0 GPa) than these of TNT.

Thermodynamic properties of 3,3-dinitroazetidinium nitrate

3,3-Dinitroazetidinium nitrate (DNAZ·HNO3) was synthesized, its thermal behaviour was studied under a non-isothermal condition by DSC and TG/DTG methods. The apparent activation energy (Ea) and pre-exponential factor (A) for the intense exothermic decomposition process were (112.52±1.37)kJ·mol−1 and (1011.91±0.06)s−1, respectively. The specific molar heat capacity (Cp,m) of DNAZ·HNO3 was determined by a continuous Cp mode of micro-calorimeter, and the Cp,m is 248.32J·K−1·mol−1 at T=298.15K. The self-accelerating decomposition temperature (TSADT), thermal ignition temperature (TTIT) and critical temperature of thermal explosion (Tb) were obtained to evaluate its thermal stability and safety. Its Cp,m, thermal stability and safety were compared with 3,3-dinitroazetidinium perchlorate (DNAZ·HClO4) and 3,3-dinitroazetidinium chloride (DNAZ·HCl).

Thermodynamic properties of 4-amino-3-furazanecarboxamidoxime

4-Amino-3-furazanecarboxamidoxime (AAOF) is an important precursor for synthesizing new furazano (furoxano) energetic compounds. Its thermal behaviour was studied under a non-isothermal condition by DSC methods. The results of this study show that there are one melting process and two exothermic decomposition processes. Its kinetic parameters of the intense exothermic decomposition process are obtained from analysis of the DSC curves. The apparent activation energy (Ea), pre-exponential factor (A) and the mechanism function (f(α)) were (146±18)kJ·mol−1, (1010.9±1.8)s−1 and (1−α)2, respectively. The specific molar heat capacity (Cp,m) of AAOF was determined by a continuous Cp mode of micro-calorimeter. The self-accelerating decomposition temperature (TSADT), thermal ignition temperature (TTIT) and critical temperatures of thermal explosion (Tb) were obtained to evaluate its thermal safety.

A comparative study of thermal behaviors and kinetics analysis of the pyrotechnic compositions containing Mg and Al

The purpose of this research is to analyze the thermal behavior and kinetics of the pyrotechnic compositions including Al + KClO4, Mg + KClO4, Al + Mg + KClO4, MgAl + KClO4 and Al + MgAl + KClO4 mixtures. The differential scanning calorimeter coupled with thermogravimetry analysis was employed to illustrate the reaction process of these pyrotechnic compositions. Moreover, the bomb calorimetry was utilized to compare experimental and theoretical heats of reaction. The apparent activation energy (Ea), frequency factor (A), the critical ignition temperature of thermal explosion and the self-accelerating decomposition temperature (TSADT), were calculated using Kissinger approach. The results showed that the composition containing MgAl had the highest activation energy and frequency factor; however, the critical ignition temperature of their oxidation reaction was lowest value. In agreement with the theoretical value, the highest experimental heat of reaction for the composition MgAl/KClO4 corresponds to the more complete combustion of metastable MgAl as an alloying mixture of Aluminum and Magnesium with equal proportions. These results suggest that benchmark values for an optimum designation and issues pertinent to the storage and handling of pyrotechnics containing Mg, Al and KClO4.

Synthesis and thermal behavior of 1,8-dihydroxy-4,5-dinitroanthraquinone manganese salt

A novel energetic combustion catalyst, 1,8-dihydroxy-4,5-dinitroanthraquinone manganese salt (DHDNEMn), was synthesized by virtue of the metathesis reaction in a yield of 91%, and its structure was characterized by IR, element analysis and differential scanning calorimetry(DSC). The thermal decomposition reaction kinetics was studied by means of different heating rate DSC. The results show that the apparent activation energy and pre-exponential factor of the exothermic decomposition reaction of DHDNEMn obtained by Kissinger’s method are 162.3 kJ/mol and 1011.8 s−1, respectively. The kinetic equation of major exothermic decomposition reaction of DHDNEMn is \(\frac{{d\alpha }} {{dT}} = \frac{{10^{11.8} }} {\beta }\frac{2} {5}(1 - \alpha )[ - \ln (1 - \alpha )]^{3/5} \exp ( - 1.623 \times 10^5 /RT) \). The entropy of activation(ΔS≠), enthalpy of activation(ΔH≠) and free energy of activation(ΔG≠) of the first thermal decomposition are −24.49 J·mol−1·K−1, 185.20 kJ/mol and 199.29 kJ/mol(T=575.5 K), respectively. The self-accelerating decomposition temperature(TSADT) and critical temperature of thermal explosion(Tb) are 562.9 and 580.0 K, respectively. The above-mentioned information on the thermal behavior is quite useful for analyzing and evaluating the stability and thermal safety of DHDNEMn.

Synthesis, crystal structure and thermal behavior of 4-amino-3,5-dinitropyrazole copper salt

A novel energetic combustion catalyst, 4-amino-3,5-dinitropyrazole copper salt ([Cu(adnp)2(H2O)2]), was synthesized in a yield of 93.6% for the first time. The single crystal of [Cu(adnp)2(H2O)2] was determined by single crystal X-ray diffraction. It crystallizes in a triclinic system, space group P−1 with crystal parameters a = 5.541(3) Å, b = 7.926(4) Å, c = 10.231(5) Å, β = 101.372(8)°, V = 398.3(3) Å3, Z = 1, μ = 1.467 mm−1, F(0 0 0) = 243, and Dc = 2.000 g cm−3. The thermal behavior and non-isothermal decomposition reaction kinetics of [Cu(adnp)2(H2O)2] were studied by means of different heating rate differential scanning calorimetry (DSC). The kinetic equation of major exothermic decomposition reaction for [Cu(adnp)2(H2O)2] was obtained. The entropy of activation (ΔS≠), enthalpy of activation (ΔH≠), free energy of activation (ΔG≠), the self-accelerating decomposition temperature (TSADT) and the critical temperature of thermal explosion (Tb) are 59.42 J mol−1 K−1, 169.5 kJ mol−1, 1141.26 kJ mol−1, 457.3 K and 468.1 K, respectively.

Nonisothermal decomposition kinetics, specific heat capacity, and adiabatic time-to-explosion of Zn(NH3)2(FOX-7)2

A new energetic zinc-FOX-7 complex, Zn(NH3)2(FOX-7)2 (FOX-7 = 1,1-diamino-2,2-dinitroethylene), was first synthesized. Thermal decomposition behavior and nonisothermal decomposition kinetics of Zn(NH3)2(FOX-7)2 were studied with DSC and TG/DTG methods. The kinetic equation obtained is $$ \frac{{{\text{d}}\alpha }}{{{\text{d}}T}} = \frac{{10^{13.99} }}{\beta }4(1 - \alpha )[ - \ln (1 - \alpha )]^{{{3 \mathord{\left/ {\vphantom {3 4}} \right. \kern-0pt} 4}}} \exp ( - 1.448 \times 10^{5} /RT) $$ . The self-accelerating decomposition temperature (T SADT) and critical temperature of thermal explosion (T b) are 183.2 and 195.8 °C, respectively. The specific-heat capacity of Zn(NH3)2(FOX-7)2 was determined with a micro-DSC method, and the molar-heat capacity is 454.6 J mol−1 K−1 at 298.15 K. Adiabatic time-to-explosion was also estimated to be about 20 s. The thermal stability of Zn(NH3)2(FOX-7)2 is good and higher than that of analogous Cu(NH3)2(FOX-7)2.

Synthesis and thermal behaviors of 1,8-dihydroxy-4,5-dinitroanthraquinone barium salt

A novel energetic green combustion catalyst, 1,8-dihydroxy-4,5-dinitroanthraquinone barium salt (DHDNEBa), was firstly synthesized by the process of metathesis reaction with a yield of 95.7%, and its structure and thermal behavior were characterized by IR, elemental analysis, thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC). The thermal decomposition kinetics and mechanism were studied by means of different heating rate DSC, thermolysis in situ rapid-scan FTIR and simultaneous TG–MS technology. The results show that the apparent activation energy and pre-exponential factor of the exothermic decomposition reaction of DHDNEBa obtained by Kissinger's method are 177.3kJmol−1 and 1013.5s−1. The entropy (ΔS≠), enthalpy (ΔH≠) and free energy of activation (ΔG≠) of the first step thermal decomposition are found to be 8.16Jmol−1K−1, 168.0kJmol−1 and 163.4kJmol−1, respectively. The self-accelerating decomposition temperature (TSADT) and critical temperature of thermal explosion (Tb) are 555.0 and 570.2K. The decomposition reaction process of DHDNEBa begins with four-molecule combined water lost in the DHDNEBa structure. The gaseous products such as H2O, CO, CO2 and NO are detected from decomposition of DHDNEBa at 606K. The residue is mainly composed of BaO and some carbon black. The above-mentioned information on thermal behavior is quite useful for analyzing and evaluating the stability and thermal safety of DHDNEBa.

BTATz–HNIW–CMDB propellants

The high nitrogen compound 3,6-bis(1H-1,2,3,4-tetrazol-5-yl-amino)-1,2,4,5-tetrazine and the high energy density material hexanitrohexaazaisowurtzitane (HNIW), were used as substitute of hexogen (RDX) in the composite modified double base (CMDB) propellant formulations, the propellant samples were prepared, the thermal behaviors, nonisothermal reaction kinetics, and thermal safety were carried out, and the eight important parameters were calculated and obtained as the self-accelerating decomposition temperature (T SADT), thermal ignition temperature (T TIT), critical temperatures of thermal explosion (T b), critical temperature of hot-spot initiation (T cr,hot-spot), characteristic drop height of impact sensitivity (H 50), critical thermal explosion ambient temperature (T acr), safety degree (S d), and thermal explosion probability (P TE). It shows that the content of HNIW has a large effect on the decomposition reaction mechanism of the CMDB propellant, when the content of HNIW is 10 %, the decomposition reaction are controlled by the random nucleation and subsequent growth (n = l), and the reaction mechanism obeys Mampel law; but when the content of HNIW is 20 %, the decomposition reaction are controlled by the chemical reaction (n = 1/4). The mechanism can not be changed by the catalysts, and they just make the apparent activation energy change slightly. For the sample, from BC01 to BC04, the values of T SADT and T TIT making an upward tendency, show the resistivity to heat: BC04 > BC03 > BC02 > BC01; the values of T acr and S d, BC01 are the maximum and BC02 are the minimum, show the heat sensitivity: BC01 > BC03 > BC04 > BC02. For the same radius, the thermal safety of the sphere sample is greater than that of the infinite cylinder one.

Thermodynamic Properties and Detonation Characterization of 3,3-Dinitroazetidinium Hydrochloride

The thermal behavior of 3,3-dinitroazetidinium hydrochloride (DNAZ·HCl) was studied at a nonisothermal condition by differential scanning calorimetric and thermogravimetric/differential thermogravimetric methods. The results show that there is only one intense exothermic decomposition process. Its kinetic parameters of the intense exothermic decomposition process are obtained from analysis of the DSC curves. The apparent activation energy (Ea), pre-exponential factor (A), and the mechanism function (f(α)) are 155.72 kJ·mol–1, 1015.84 s–1 and 3α2/3, respectively. The specific heat capacity (Cp) of DNAZ·HCl was determined with a continuous Cp mode of microcalorimeter. The specific molar heat capacity (Cp,m) of DNAZ·HCl was 205.10 J·mol–1·K–1 at 298.15 K. The self-accelerating decomposition temperature (TSADT), thermal ignition temperature (TTIT), and critical temperatures of thermal explosion (Tb) were obtained to evaluate the thermal stability and safety of DNAZ·HCl. The detonation velocity (D) and detonation pressure (P) of DNAZ·HCl were estimated using the nitrogen equivalent equation according to the experimental density. The stability, safety, and detonation performance of DNAZ·HCl were compared with that of 3,3-dinitroazetidinium 3,5-dinitrosalicylate (DNAZ·HClO4).

Thermal Properties of 1-Amino-1-hydrazino-2,2-dinitroethylene Cesium Salt

A new high-energy organic cesium salt, 1-amino-1-hydrazino-2,2-dinitroethylene cesium salt [Cs(AHDNE)], was synthesized by reacting of 1-amino-1-hydrazino-2,2-dinitroethylene (AHDNE) and cesium chloride in alkali methanol aqueous solution. The thermal behavior and nonisothermal decomposition kinetics of Cs(AHDNE) were studied. The kinetic equation obtained is . The self-accelerating decomposition temperature (TSADT) and critical temperature of thermal explosion (Tb) of Cs(AHDNE) are 152.9 and 163.5°C, respectively. The specific heat capacity of Cs(AHDNE) was determined with a micro-differential scanning calorimetry (DSC) method, and the molar heat capacity was 223.62 J mol−1 K−1 at 298.15 K. The adiabatic time to explosion of Cs(AHDNE) was 93.5 s. Cs(AHDNE) has higher thermal stability than AHDNE. Cs(AHDNE) is sensitive to impact and friction.

Novel magnesium salt based on BTATz: Crystal structure, thermal behavior and thermal safety

A new high-energy organic magnesium salt [Mg(H2O)6](BTATz)·2H2O[BTATz=3,6-bis(1H-1,2,3,4-tetrazol-5-yl-amino)-1,2,4,5-tetrazine] was synthesized and characterized by elemental analysis and Fourier transform infrared(FTIR) spectrometry. Its crystal structure was determined by X-ray single crystal diffraction. The crystal belongs to monoclinic system with space group C2/c and a=2.1329(7) nm, b=0.52275(16) nm, c=1.5909(5) nm, β=100.471(6)°, V=1.7443(9) nm3, Z=4, µ=0.361 mm−1, F(000)=900 and D c=1.644 g/cm3. Meanwhile, the thermal behavior of [Mg(H2O)6](BTATz)·2H2O was studied under the non-isothermal conditions by differential scanning calorimetry( DSC) and thermalgravity-differential thermalgravity(TG-DTG) methods. The enthalpy, apparent activation energy and per-exponential factor of the main exothermic decomposition reaction are 898.88 J/g, 139.2 kJ/mol and 1010.48 s−1, respectively. The values of the self-accelerating decomposition temperature(T SADT), the thermal ignition temperature(T TIT) and the critical temperature of thermal explosion(T b) for [Mg(H2O)6](BTATz)·2H2O are 515.13, 532.08 and 565.99 K, respectively.

Synthesis, crystal structure and thermal behaviors of 2,3-dihydro-4-nitro-3-(dinitromethylene)-1H-pyrazol-5-amine potassium salt [K(NNMPA)

A novel high-energy organic potassium salt, 3-(dinitromethylene)-4-nitro-2,3-dihydro-1H-pyrazol-5-amine potassium salt [K(NNMPA)], was first synthesized by an unexpected reaction of 1-amino-1-hydrazino-2,2-dinitroethylene (AHDNE) and KOH in methanol aqueous solution. K(NNMPA) was characterized by elemental analysis, IR spectra, 13C NMR and single-crystal X-ray diffraction. K(NNMPA) crystallized in monoclinic system, space group P21/c with crystal parameters of a=9.358(3)Å, b=13.079(4)Å, c=7.568(2)Å, β=107.344(5)°, V=884.2(5)Å3, Z=4, μ=0.638mm−1, F(000)=544 and Dcalc=2.03gcm−3. Thermal decomposition of K(NNMPA) was studied with DSC and TG-DTG methods and presents two exothermic decomposition processes. The kinetic equation of the first process obtained is dαdT=1018.42β4(1-α)[-ln(1-α)]3/4exp(-1.665×105/RT). The self-accelerating decomposition temperature (TSADT) and critical temperature of thermal explosion (Tb) of K(NNMPA) are 137.4 and 146.3°C, respectively. K(NNMPA) exhibits lower thermal stability than K(AHDNE).