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.
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.
Authors:S. Jirong, C. Zhaxou, Hu Rongzu, X. Heming, and L. Fuping
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, Dc=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.
Authors:L. Rong, N. Binke, W. Yuan, Y. Zhengquan, and Hu Rongzu
Two methods for estimating the critical temperature (Tb) 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–To/T)]e–E/RT, using reasonable hypotheses. We can easily obtain the values of the thermal decomposition activation energy (E), the onset temperature (Te) and the initial temperature (To) at which DSC curve deviates from the baseline of the non-isothermal DSC curve of HNNC, and then calculate the critical temperature (Tb) of thermal explosion by the two derived formulae. The results obtained with the two methods for HNNC are in agreement to each other.
Authors:Hu Rongzu, Wu Shanxiang, Liang Yanjun, Sun Lixia, and Yang Zhengquan
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).
Authors:Xie Yi, Hu Rongzu, Zhang Tonglai, and Li Fuping
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:
Authors:N. Binke, L. Rong, C. Xianqi, W. Yuan, Hu Rongzu, and Y. Qingsen
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 (
Hm), melting entropy (
Sm), the enthalpy of decomposition (
Hdec) and the heat-temperature quotient (
Sdec) 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
Authors:N. Binke, L. Rong, Y. Zhengquan, W. Yuan, Y. Pu, Hu Rongzu, and Y. Qingsen
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
Authors:Hu Rongzu, Li Jiamin, Liang Yanjun, Wu Shanxiang, Sun Lixia, and Wang Yaping
The enthalpies of the crystal transformation from I to II and from II to III and the melting enthalpy of 2,2,2-trinitroethyl-4,4,4-trinitrobutyrate (TNETB) are determined by means of Calvet microcalorimeter. On cooling, the supercooing from liquid to solid does not appear, and form II will transform to form I when 71.8° C is reached. The phase diagrams of TNETB-2,4,6-trinitrotoluene (TNT) and TNETB-polyester systems have been constructed by differential scanning calorimetry (DSC). The eutectic temperatures are 56° C and 34° C respectively. The compositions corresponding to the eutectic points are 52 and 46 weight percent TNETB respectively.