Nonisothermal decomposition and safety parameters of HNIW/TNT cocrystal.

To explore the thermal decomposition behavior and evaluate the thermal safety of the cocrystal 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (HNIW)/2,4,6-trinitrotoluene (TNT), its thermal and kinetic behaviors were studied by differential scanning calorimetry (DSC) technique. With the help of onset temperature (T e) and maximum peak temperature (T p) from the non-isothermal DSC curves of HNIW/TNT cocrystal at different heating rates (ß), the following were calculated: the value of specific heat capacity (C p) and the standard molar enthalpy of formation , the apparent activation energy (E K and E O) and pre-exponential constant (A K) of thermal decomposition reaction obtained by Kissinger's method and Ozawa's method, density (ρ) and thermal conductivity (λ), the decomposition heat (Q d, as half-explosion heat), Zhang-Hu-Xie-Li's formula, Smith's equation, Friedman's formula, Bruckman-Guillet's formula, Frank-Kamenetskii's formula and Wang-Du's formulas, the values (T e0 and T p0) of T e and T p corresponding to ß â†’ 0, thermal explosion temperature (T be and T bp), adiabatic time-to-explosion (t tiad), 50% drop height (H 50) for impact sensitivity, critical temperature of hot-spot initiation (T cr), thermal sensitivity probability density function [S(T)] vs. temperature (T) relation curves with radius of 1 m and ambient temperature of 300 K, the peak temperature corresponding to the maximum value of S(T) vs. T relation curve (T S(T)max), safety degree (SD) and critical ambient temperature (T acr) of thermal explosion. Results show that the kinetic equation describing the exothermic decomposition reaction of HNIW/TNT cocrystal is The following thermal safety parameters for the HNIW/TNT cocrystal are obtained: T e0 = 464.45 K; T p0 = 477.55 K; T be = 472.82 K; T bp = 485.89 K; t tiad = 4.40 s, 4.42 s, and 4.43 s for n = 0, 1, and 2, respectively; T cr = 531.90 K; H 50 = 19.46 cm; and the values of T acr, T S(T)max, SD and P TE are 469.69 K, 470.58 K, 78.57% and 21.43% for sphere; 465.70 K, 470.58 K, 78.17% and 21.83% for infinite cylinder; and 459.39 K, 464.26 K, 77.54% and 22.46% for infinite flat.

DFT studies of the adsorption and dissociation of H2O on the Al13 cluster: origins of this reactivity and the mechanism for H2 release.

A theoretical study of the chemisorption and dissociation pathways of water on the Al13 cluster was performed using the hybrid density functional B3LYP method with the 6-311+G(d, p) basis set. The activation energies, reaction enthalpies, and Gibbs free energy of activation for the reaction were determined. Calculations revealed that the H2O molecule is easily adsorbed onto the Al13 surface, forming adlayers. The dissociation of the first H2O molecule from the bimolecular H2O structure via the Grotthuss mechanism is the most kinetically favorable among the five potential pathways for O-H bond breaking. The elimination of H2 in the reaction of an H2O molecule with a hydrogen atom on the Al cluster via the Eley-Rideal mechanism has a lower activation barrier than the elimination of H2 in the reaction of two adsorbed H atoms or the reaction of OH and H. Following the adsorption and dissociation of H2O, the structure of Al13 is distorted to varying degrees.

Non-isothermal decomposition kinetics, heat capacity and thermal safety of 37.2/44/16/2.2/0.2/0.4-GAP/CL-20/Al/N-100/PCA/auxiliaries mixture.

The specific heat capacity (C(p)) of 37.2/44/16/2.2/0.2/0.4-GAP/CL-20/Al/N-100/PCA/auxiliaries mixture was determined with the continuous C(p) mode of microcalorimeter. The equation of C(p) with temperature was obtained. The standard molar heat capacity of GAP/CL-20/Al/N-100/PCA/auxiliaries mixture was 1.225 J mol(-1)K(-1) at 298.15K. With the help of the peak temperature (T(p)) from the non-isothermal DTG curves of the mixture at different heating rates (ß), the apparent activation energy (E(k) and E(o)) and pre-exponential constant (A(K)) of thermal decomposition reaction obtained by Kissinger's method and Ozawa's method. Using density (ρ) and thermal conductivity (λ), the decomposition heat (Q(d), taking half-explosion heat), Zhang-Hu-Xie-Li's formula, the values (T(e0) and T(p0)) of T(e) and T(p) corresponding to ß â†’ 0, thermal explosion temperature (T(be) and T(bp)), adiabatic time-to-explosion (t(TIad)), 50% drop height (H(50)) of impact sensitivity, and critical temperature of hot-spot initiation (T(cr,hot spot)) of thermal explosion of the mixture were calculated. The following results of evaluating the thermal safety of the mixture were obtained: T(be) = 441.64K, T(bp) = 461.66 K, t(Tlad) = 78.0 s (n = 2), t(Tlad) = 74.87 s (n = 1), t(Tlad) = 71.85 s (n = 0), H(50) = 21.33 cm.

Non-isothermal thermal decomposition reaction kinetics of 2-nitroimino-5-nitro-hexahydro-1,3,5-triazine (NNHT).

The thermal behavior and decomposition reaction kinetics of 2-nitroimino-5-nitro-hexahydro-1,3,5-triazine (NNHT) were investigated by TG-DTG and DSC under atmospheric pressure and flowing nitrogen gas conditions. The results show that the thermal decomposition process of NNHT has two mass loss stages. The exothermic decomposition reaction mechanism obeys chemical reaction rule. The kinetic parameters of the reaction are E(a)=131.77 kJ mol(-1), lg(A/s(-1))=12.56, respectively. The kinetic equation can be expressed as: dalpha/dt = 10(12.86)(1-alpha)(3/2)3(-1.5849 x 10(4)/T)). The critical temperature of thermal explosion of NNHT obtained from the peak temperature (T(p)) is T(bp)=467.22K. The entropy of activation (DeltaS( not equal)), enthalpy of activation (DeltaH( not equal)), and free energy of activation (DeltaG( not equal)) of the reaction are -7.978 J mol(-1)K(-1), 127.99 kJ mol(-1) and 131.62 kJ mol(-1), respectively.

Effects of pressure and TEGDN content on decomposition reaction mechanism and kinetics of DB gun propellant containing the mixed ester of TEGDN and NG.

The effects of pressure and triethyleneglycol dinitrate (TEGDN) content on the decomposition reaction mechanism and kinetics of the double-base (DB) gun propellant composed of mixed ester of TEGDN and nitroglycerin (NG), and nitrocellulose (NC) were investigated by high-pressure differential scanning calorimetry (PDSC). The results show that the high pressure can decrease the DSC peak temperature, increase the decomposition heat; with the increase in the content of TEGDN, the decomposition heat decreases below 2MPa and rises at 4MPa. The high pressure can change the decomposition reaction mechanism and the kinetics of the DB gun propellant under 0.1MPa; the high TEGDN content does not change the mechanism functions, and the kinetic equation has a little difference between the sample and the control propellant; the high pressure makes the critical temperature (T(be)) of thermal explosion of the sample decrease, while the high TEGDN content make it present a increasing trend, and the DB gun propellant containing high content of TEGDN has a better thermal stability.

Thermal decomposition and kinetics studies on 1,4-dinitropiperazine (DNP).

DNP, a nitramine, has been studied with regard to the kinetics and mechanism of thermal decomposition, using thermogravimetry (TG), differential thermal analysis (DTA), infrared (IR) spectroscopy, and differential scanning calorimetry (DSC). The IR spectra of DNP have also been recorded and the kinetics of thermolysis has been followed by non-isothermal TG. The activation energy of the solid-state process was determined using Flynn-Wall-Ozawa method. The actual reaction mechanism obeyed nucleation and growth model, Avramie Erofeev function (n=1) with integral form Galpha=-ln(1-alpha) (alpha=0.10-0.65). Ea and A were determined to be 116.51 kJ/mol and 10(10.52) s(-1). The T/Jump FT-IR analysis showed that CH2O, NO2, and NO are produced in larger amounts than CO2 and HCN. The cleavage of the N-N and C-N bond appears to be the primary step in the thermolysis of DNP.

Preparation, characterization, non-isothermal reaction kinetics, thermodynamic properties, and safety performances of high nitrogen compound: hydrazine 3-nitro-1,2,4-triazol-5-one complex.

A new high nitrogen compound hydrazine 3-nitro-1,2,4-triazol-5-one complex (HNTO) was prepared by the reaction of 3-nitro-1,2,4-triazol-5-one with hydrazine hydrate, and its structure was characterized by means of organic elemental analyzer, FT-IR, XRD, (13)C NMR and (15)N NMR. The non-isothermal reaction kinetics of the main exothermic decomposition reaction of HNTO was investigated by means of DSC. The thermodynamic properties of HNTO were calculated. The results showed that the formation of HNTO is achieved by proton transfer of N(4) atom, and it makes a higher nitrogen content and lower acidity. The reaction mechanism of HNTO is classified as nucleation and growth, and the mechanism function is Avramo-Erofeev equation with n=2/5. The kinetic parameters of the reaction are E(a)=195.29 kJ mol(-1), lg(A (s(-1)))=19.37, respectively. The kinetic equation can be expressed as: d(alpha)/d(t) = 10(18.97)(1 - alpha)[-ln(1 - alpha)](3/5) e(-2.35 x 10(4)/T). The safety performances of HNTO were carried out. The critical temperature of thermal explosion are 464.26 and 474.37 K, the adiabatic time-to-explosion is 262s, the impact sensitivity H(50)=45.7 cm, the friction sensitivity P=20% and the electrostatic spark sensitivity E(50)>5.4J (no ignition). It shows that HNTO has an insensitive nature as RDX and NTO, etc.