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  • Author or Editor: Rongzu Hu x
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Abstract  

From measurements of the enthalpy of solution of metal salts of 3-nitro-1,2,4-triazol-5-one (NTO) in water, the standard enthalpies of formation of KNTO·H2O, Ba(NTO)2·3H2O, LiNTO·2H2O, Ca(NTO)2·4H2O and Gd(NTO)3·7H2O were determined as −(676.9±2.6), −(1627.0±2.5), −(966.6.3±2.2), −(1905.5±4.4) and −(3020.1±6.4) kJ·mol−1, respectively. From measurements of the enthalpy of precipitation of KNTO·H2O crystal with Pb(NO3)2(aq), CuSO4(aq) and Zn(NO3)2(aq), the standard enthalpies of formation of Pb(NTO)2·H2O, Cu(NTO)2·2H2O and Zn(NTO)2·H2O were determined as −(247.4±5.9), −(712.1±5.4) and −(628.8±5.7) kJ·mol−1, respectively.

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Abstract  

The phase transition curves of a multi-component TN liquid crystal mixture (TN 88-1) and a multi-component cholesteric liquid crystal mixture (Ch 88-2) were plotted by using a differential scanning calorimeter. The phase transition temperature and phase transition heat were obtained from the DSC curves. The results show that the components of TN 88-1 are compatible and they can form a stable mixture with CB 15 chiral liquid crystal. The components of Ch 88-2 are not compatible and Poly (MMA-BMA) can greatly improve their compatibility.

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Three new rare-earth metal (Pr, Nd and Sm) salt hydrates of 3-nitro-1,2,4-triazol-5-one (NTO) were prepared and characterized. The thermal behaviour of the three salt hydrates, M(NTO)3·nH2O (M=Pr and Nd,n=9;M=Sm,n=8) were studied by means of TG and DSC under conditions of linear temperature increase. The thermal decomposition intermediates were determined by means of IR, MS and X-ray diffraction spectrometry. The thermal decomposition mechanisms of these hydrates were proposed as follows:

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Abstract  

The single crystal of lead salt of 3-nitro-1,2,4-triazol-5-one (NTO), [Pb(NTO)2(H2O)] was prepared and its structure was determined by a four-circle X-ray diffractometer. The crystal is monoclinic, its space group is P21/n with crystal parameters of a=0.7262(1) nm, b=1.2129(2) nm, c=1.2268(3) nm, =90.38(2)°, V=1.0806(2) nm3, Z=4, D c=2.97 g cm–3, µ=157.83cm–1, F(000)=888. The final R is 0.027. By using SCF-PM3-MO method we obtained optimized geometry for [Pb(NTO)2 H2O] and particularly positions for hydrogen atoms. Through the analyses of MO levels and bond orders it is found that Pb atom bond to ligands mainly with its 6pz and 6py AOs. The thermal decomposition experiments are elucidated when [Pb(NTO)2 H2O] is heated, ligand water is dissociated first and NO2 group has priority of leaving. Based on the thermal analysis, the thermal decomposition mechanism of [Pb(NTO)2 H2O] has been derived. The lattice enthalpy and its lattice energy were also estimated.

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Abstract  

Two methods for estimating the critical temperature (T b) of thermal explosion for the highly nitrated nitrocellulose (HNNC) are derived from the Semenov's thermal explosion theory and two non-isothermal kinetic equations, d/dt=Af()e–E/RT and d/dt=Af()[1+E/(RT)(1–T o/T)]e–E/RT, using reasonable hypotheses. We can easily obtain the values of the thermal decomposition activation energy (E), the onset temperature (T e) and the initial temperature (T o) at which DSC curve deviates from the baseline of the non-isothermal DSC curve of HNNC, and then calculate the critical temperature (T b) of thermal explosion by the two derived formulae. The results obtained with the two methods for HNNC are in agreement to each other.

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A numerical method of computing the kinetic parameters

Exothermic decomposition of energetic materials via the exothermic rate equation

Journal of Thermal Analysis and Calorimetry
Authors: Hu Rongzu, Wu Shanxiang, Liang Yanjun, Sun Lixia, and Yang Zhengquan

Abstract  

A numerical method of computing the kinetic parameters (the activation energy (E), the preexponential constant (A) and the reaction order (n)) of exothermic decomposition of energetic materials via the exothermic rate equation is presented. The values ofE, A, andn are reported for the exothermic decomposition of six typical energetic materials, 1,6-diazido-2,5-dinitrazahexane (I), 1,5-diazido-3-nitrazapentane (II), 2,2,4,7,9,9-hexanitro-5-methyl-4,7-dinitrazadecane (III), 2,2,2-trinitroethyl-4,4,4-trinitrobutyrate (IV), 1,4-dinitro-2,3-dioxo-1,4-dinitrazacyclohexane (V) and 1,3,5-trianitro-1,3,5-triazafurazano[3,4-f]cycloheptane (VI).

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Journal of Thermal Analysis and Calorimetry
Authors: Jianjun Li, Xuguang Wang, Rongzu Hu, Bin Kang, Yuxiang Ou, and Boren Chen

Abstract  

The determination of the most probable mechanism function and the calculation of kinetic parameters of thermal decomposition of powder emulsion explosives have been achieved by different kinetic equations and different kinetic methods from data non-isothermal SC-DSC curves, DSC curves, and thermal explosion delay curve. The courses which the reaction would follow under adiabatic conditions are predicted.

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Abstract  

The melting process of NC is studied by using modulated differential scanning calorimetry (MDSC) technique, the microscope carrier method for measuring the melting point and the simultaneous device of the solid reaction cell in situ/RSFT-IR. The results show that the endothermic process in the MDSC curve is reversible. It is caused by the phase change from solid to liquid of the mixture of initial NC, decomposition partly into condensed phase products. The values of the melting point, melting enthalpy ( H m), melting entropy ( S m), the enthalpy of decomposition ( H dec) and the heat-temperature quotient ( S dec) obtained by the MDSC curve of NC at a heating rate of 10 K min–1 are 476.84 K, 205.6 J g–1, 0.4312 J g–1 K–1, –2475.0 J g–1 and –5.242 Jg–1K–1, respectively. The MDSC results of NC with different nitrogen contents show that with increasing the nitrogen content in NC, the absolute values of H m, S m, H dec and S dec increase.

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Abstract  

The kinetics of the first order autocatalytic decomposition reaction of highly nitrated nitrocellulose (HNNC, 14.14%N) was studied by using thermogravimetry (TG). The results show that the TG curve for the initial 50% of mass-loss of HNNC can be described by the first order autocatalytic equation

\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\frac{{{\text{d}}y}}{{dt}} = - 10^{16.4} \exp \left( { - \frac{{210380}}{{RT}}} \right)y - 10^{16.7} \exp \left( { - \frac{{171205}}{{RT}}} \right)y(1 - y)$$ \end{document}
and that for the latter 50% mass-loss of HNNC described by the reaction equations
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\frac{{dy}}{{dy}} = - 10^{16.3} \exp \left( { - \frac{{169483}}{{RT}}} \right)y\quad (n = 1)$$ \end{document}
and
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\frac{{dy}}{{dt}} = - 10^{16.8} \exp \left( { - \frac{{165597}}{{RT}}} \right)y^{2.61} \quad (n \ne 1)$$ \end{document}

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