Nonisothermal decomposition kinetics and computational studies on the properties of 2,4,6,8-tetranitro-2,4,6,8-tetraazabicyclo[3,3,1]onan-3,7-dione (TNPDU)

The thermal decomposition and the nonisothermal kinetics of the thermal decomposition reaction of 2,4,6,8-tetranitro-2,4,6,8-tetraazabicyclo[3,3,1]onan-3,7-dione (TNPDU) were studied under the nonisothermal condition by differential scanning calorimetry (DSC) and thermogravimetry-derivative thermogravimetry (TG-DTG) methods. The kinetic model function in differential form and the value of Ea and A of the decomposition reaction of TNPDU are f(alpha) = 3(1 - alpha)[-ln(1 - alpha)](2/3), 141.72 kJ mol(-1), and 10(11.99) s(-1), respectively. The critical temperature of thermal explosion of the title compound is 232.58 degrees C. The values of DeltaS(++), DeltaH(++), and DeltaG(++) of this reaction are -15.50 J mol(-1) K(-1), 147.65 kJ mol(-1), and 155.26 kJ mol(-1), respectively. The theoretical investigation on the title compound as a structure unit was carried out by the DFT-B3LYP/6-311++G** method. The IR frequencies and NMR chemical shift were performed and compared with the experimental results. The heat of formation (HOF) for TNPDU was evaluated by designing isodesmic reactions. The detonation velocity (D) and detonation pressure (P) were estimated by using the well-known Kamlet-Jacobs equation, based on the theoretical densities and HOF. The calculation on bond dissociation energy suggests that the N-N bond should be the trigger bond during the pyrolysis initiation process.     

纳米结晶体Ni0.5Zn0.5Fe2O4对高氯酸铵热行为及分解反应动力学的影响

采用差示扫描量热法(DSC)、热重和微分热重(TG-DTG)及固相原位反应池/快速扫描傅立叶变换红外联用技术(hyphenated in situ thermolysis/RSFTIR)研究了纳米结晶体Ni_0.5Zn_0.5Fe₂O₄与高氯酸铵(AP)组成的混合物的热行为和分解反应动力学。结果表明：Ni_0.5Zn_0.5Fe₂O₄使得AP的低、高温分解放热峰温分别提前17.44 K和27.74 K,并使得对应的分解热分别增加3.7 J·g^-1和193.7 J·g^-1。Ni_0.5Zn_0.5Fe₂O₄并不影响AP的晶转温度和晶转热。Ni_0.5Zn_0.5Fe₂O₄使得AP的TG曲线出现3个阶段,并使得后2个失重阶段的初始和终止温度都有所提前。凝聚相分解产物分析表明Ni_0.5Zn_0.5Fe₂O₄加速了凝聚相AP的分解及氨气的释放。含Ni_0.5Zn_0.5Fe₂O₄的AP的高温分解反应的动力学参数E_a=238.88 kJ·mol^-1,A=1018.59 s^-1,动力学方程可表示为dα/dt=10^18.99(1-α)[-ln(1-α)]^3/5e^-2.87×104T。始点温度(T_e)和峰顶温度(T_p)计算得出AP的热爆炸临界温度值分别为:574.83 K和595.41 K。分解反应的活化熵(ΔS^≠)、活化焓(ΔH^≠)和活化能(ΔG^≠)分别为:109.61 J·mol^-1·K^-1、236.49 kJ·mol^-1及172.58 kJ·mol^-1。     

N-(苯乙酰氨基)-N’-(α-萘乙酰基)硫脲的热解机理及热动力学研究

采用热重法(TG)和微分热重法(DTG)对合成的新型酰氨基硫脲类化合物——N-(苯乙酰氨基)-N’-(α-萘乙酰基)硫脲进行了热稳定性研究, 在25～600 ℃范围内有两次失重过程. 通过量子化学方法计算了分子的Mayer键级, 据此计算结果和热重分析结果提出了其热解机理. 并运用Kissinger和Ozawa等方法计算了其热解动力学参数. 得到第一阶段热解动力学方程为: dα/dt＝541.5exp(－38350/RT)(1－α)2.58; 第二阶段热解动力学方程为: dα/dt＝505.2exp(－64810/RT)• (1－α)2.12.     

Thermal Kinetics and Decomposition Mechanism of 1-Amino-1,2,3-triazolium Nitrate

The thermal decomposition kinetics of 1-amino-l,2,3-triazolium nitrate（ATZ-NO3） was investigated by non-isothermal TG-DTG at various heating rates（2,5,10,15 and 20 ℃/min）.The results show that the thermal decomposition of ATZ-NO3 consists of two stages corresponding to the losing of nitrate anion,substituent group and the splitting of triazole ring respectively.The kinetic triplets of the two stages were described by a three-step method.First,the differential Kissinger and intergral Ozawa methods were used to calculate the apparent activation energies（E） and pre-exponential factors（A） of the two decomposition stages.Second,two calculation methods（intergral （S）atava-（S）esták and differential Achar methods） were used to obtain several probable decomposition mechanism functions.Third,three judgment methods（average,double-extrapolation and Popescu methods） were used to confirm the most probable decomposition mechanism functions.Both reaction models of the two stages were randominto-nucleation and random-growth mechanisms with n=3/2 for the first stage and n=1/3,m=3 for the second stage.The kinetic equations for the two decomposition stages of ATZ-NO3 may be expressed as da/dt=1013.60·e-128970/RT（1-α）[-1n（1-α）]-1/2 and da/dt=1011.41·e-117370/RT（1-α）[-1n（1-α）]-2/3.The thermodynamic parameters including Gibbs free energy of activation（△G≠）,entropy of activation（△S≠） and enthalpy of activation（△H≠）,for the thermal decomposition reaction were also derived.     

Oxidation and decomposition kinetics of thiourea oxides

In this report the decomposition and oxidation kinetics of thiourea dioxide and thiourea trioxide are investigated with a reversed-phase ion-pair high-performance liquid chromatography (HPLC) method. The HPLC method allows us to simultaneously determine and quantify several sulfur-containing reagents such as (NH2)2CSO2, (NH2)2CSO3, (NH2)2CO, and SO3(2-) (HSO3-). Experiments illustrate that the decomposition of thiourea oxides is a first-order reaction, in which the rate constants increase with the pH of the solution. Oxidations of thiourea oxides by hydrogen peroxide are first order with respect to both reagents within the studied pH range between 4.0 and 8.0. Oxidation rate constants are measured under different pH conditions, which show that increasing the pH of the reaction solution significantly accelerates the oxidation process.     

硝酸舍他康唑的热分解机理及动力学

采用热重法(TG)、差示扫描量热法(DSC)测定了硝酸舍他康唑(STCZ)在氮气氛和空气氛中的热分解过程,结果表明STCZ的热分解过程是一个三阶段过程。运用量子化学GAMESS软件计算了STCZ分子的键级,测定了STCZ及其在热分解过程中不同阶段残留物的红外光谱,推断了STCZ的热分解机理,起始步骤是硝酸的分解。根据不同升温速率下的热重曲线计算得到STCZ第一阶段热分解反应的动力学参数,在氮气中,表观活化能Ea=222.2 kJ.mol-1,指前因子A=4.467×1024min-1,在空气中,表观活化能Ea=177.2 kJ.mol-1,指前因子A=1.738×1019min-1。推算了不同使用温度下STCZ的预期寿命。     

柠檬酸铋的热分解机理、 非等温反应动力学及其对双基推进剂燃烧的催化作用

用TG和DSC以及变温固相原位反应池/傅里叶红外光谱(RSFTIR)联用技术研究了柠檬酸铋的热分解行为, 提出了可能的反应机理, 并计算了主分解反应的动力学参数. 柠檬酸铋主分解反应的表观活化能和指前因子分别为213.82 kJ/mol和1016.48 s^-1. 将柠檬酸铋应用到双基推进剂配方中研究其对双基推进剂燃烧性能的影响, 结果表明, 柠檬酸铋对双基推进剂燃烧有良好的催化作用, 能显著提高双基推进剂的燃速, 降低压力指数, 特别是与少量炭黑(CB)复合后, 对双基推进剂燃烧的催化效果更好.     

阿司匹林的热解机理及热动力学研究

在用热重法研究了阿司匹林的热稳定性实验的基础上,通过量子化学方法(ab initio DFT)计算了阿司匹林分子的键级,据此计算结果提出了阿司匹林的热解机理,按此机理得到的理论计算值与实验结果一致;运用Freeman-Carroll、Kissinger和Ozawa三种方法分别计算了阿司匹林的热解动力学参数:活化能(E)、反应级数(n)和指前因子(A),其热解动力学方程为: dα/dt=4.74×1011[exp(－(100.34±5.18)×103/RT)](1－α)2.8±0.3;用差示扫描量热法测定的该物质的熔点、摩尔熔化焓和摩尔熔化熵分别为(409.19 ± 0.22) K、(29.17 ± 0.41) kJ•mol-1和(71.09±1.06) J•mol-1•K-1.     

地开石热分解过程及非等温动力学研究

Fourier-transform infrared emission spectroscopy was used to study the dehydroxylation behavior of the thermal decomposition of dickite from Chenxi, Hunan Province, China. Dehydroxylation of dickite was followed by a loss of intensity of the 3620.73, 3695.34 cm-1 OH-stretching bands and 916.06, 1009.33 cm-1 OH bending bands. The thermal decomposition was investigated by thermogravimetric analysis (TGA). A good agreement is found with TG curves of dickite and the mass loss is 13.7% (close to the theoretical value). The non-isothermal kinetics of the thermal decomposition of dickite was studied in TG-DTG curves over the temperature range from 298 K to 1123 K by thermogravimetry and differential thermal analysis in air. Mathematical analysis of TG-DTG data using the integral methods (Coats-Redfern equation, HM equation, MKN equation) and differential method (Achar equation) shows that the thermal decomposition of dickite accords F2 mechanism. The kinetic parameters such as the activation energy (E=131.62 kJ/mol), pre-exponential factor (A=108.30 s-1) and reaction order (n=2.1) are reported. The Ozawa method was used to analyse the activation energy of the same sample at different heating rate and gave 133.07 kJ/mol. The kinetic parameters calculated from different equation are rather close to each other.     

Differences in thermal decomposition of Ag(I), Mn(II), Fe(II) and Fe(III) complexes of cyclic dithiocarbamates

The thermal decomposition of pyrrolidinedithiocarbamate (Pyr) and piperidinedithiocarbamate (Pip) complexes of Ag(I), Mn(II), Fe(II) and Fe(III) have been investigated by thermogravimetry and differential scanning calorimetry. The decomposition intermediates and final products were identified from their X-ray diffraction patterns. Changes in their IR spectra were correlated with their thermogravimetric profiles. The hydrated compounds decomposed without loss of water and oxides were detected as the final decomposition products even in nitrogen atmosphere.     

含CL-20的改性双基推进剂的热行为及非等温反应动力学

用DSC和TG方法研究了含六硝基六氮杂异伍兹烷(CL-20)的改性双基推进剂在常压(0.1 MPa)和高压(4和7 MPa)下的热行为和高压下的热分解反应动力学. 结果表明, 该推进剂常压下DSC曲线有3个放热峰, 相应TG曲线有3个失重过程; 而高压下DSC曲线只有一个放热峰, 高压下放热峰的峰温随加热速率增大而升高. 高压下该推进剂放热分解反应机理和反应动力学参数受测试环境压强影响较弱, 反应机理是随机成核和随后生长, 放热分解反应的动力学方程可以表示为, 4 MPa时, dα/dt=1014.5(1-α)[-ln(1-α)]1/3e-17981.7/T; 7 MPa时, dα/dt=1014.7(1-α)·[-ln(1-α)]1/3e-18138.1/T.     

The effect of gamma-irradiation on the thermal decomposition of anhydrous cadmium nitrate

The thermal decomposition of -irradiated anhydrous cadmium nitrate was studied by dynamic thermogravimetry. The reaction order, activation energy, frequency factor and entropy of activation were calculated by the Coats-Redfern method and were compared with those of the unirradiated salt. Irradiation enhances the decomposition and the effect increases with the irradiation dose. The activation energy decreases on irradiation. The mechanism of the decomposition of unirradiated and irradiated anhydrous cadmium nitrate follows the Mampel equation: -ln(1-) for g() and the rate-controlling process is random nucleation with the formation of a nucleus on every particle.     

柠檬酸镧催化双基推进剂的非等温热分解反应动力学

采用TG-DTG和DSC技术研究了含二缩三乙二醇二硝酸酯(TEGDN)和硝化甘油(NG)的混合酯、硝化棉(NC)和用作燃烧催化剂的柠檬酸镧组成的双基推进剂在常压和流动态氮气气氛下的非等温热分解反应动力学. 结果表明, 该双基推进剂的热分解过程存在2个失重阶段: 第I失重阶段为混合酯的挥发分解过程; 第II失重阶段为主放热分解反应, 机理服从三级化学反应, 减速型α-t曲线, 动力学参数: Ea=231.14 kJ·mol-1, A=10^23.29 s-1, 动力学方程为dα/dt=10^22.99(1-α)³ e^-2.78×104/T. 由外推起始点温度(Te)和峰顶温度(Tp)计算得出该双基推进剂的热爆炸临界温度值分别为Tbe=463.62 K, Tbp=477.88 K. 反应的活化熵(⊿S^≠)、活化焓(⊿H^≠)和活化能(⊿G^≠)分别为219.75 J·mol-1·K-1, 239.23 kJ·mol-1和135.96 kJ·mol-1.     

Thermal Behavior, Non-isothermal Decomposition Reaction Kinetics of Copper（Ⅱ） Salt of 4-Hydroxy-3,5-dinitropyridine and Its Application in Propellant

IntroductionCopper( ) salt of4- hydroxy- 3,5 - dinitropy-ridine( 4 HDNPCu) is an energetic material contain-ing energetic_ NO2 groups,which can be used asan energetic auxiliary catalyzer substituting the in-ertia copper salt to improve the catalysis of themain catalyzer( lead salt) in propellant[1] .Thermalbehavior is one of the most important aspects af-fecting its catalytic efficiency for propellant.How-ever,its kinetic parameters of thermal decomposi-tion and its application in RDX- co…     

氟橡胶/改性乙丙橡胶并用胶的热稳定性

采用热分析技术考察了氟橡胶及氟橡胶(FPM)/改性乙丙橡胶(MEPDM)并用胶在氮气中的热稳定性, 通过微分法与积分法两种动力学方法计算出了FPM及FPM/MEPDM并用胶的热分解活化能E和指前因子A. 结果表明, 并用胶的热分解温度稍高于纯的氟橡胶, 但热分解活化能略低于氟橡胶, FPM、FPM/MEPDM(5%)和FPM/MEPDM(10%)的热分解活化能分别为251.74、244.98和219.60 kJ·mol-1; 热分解反应级数n均为0.95. 随着失重百分率的增大, 热分解活化能增大.     

双[2-(2'-苯氧基)苯并恶唑]二吡啶合锰(II)配合物的研究

X射线晶体结构分析结果表明, 标题化合物晶体(C36H26MnN4O4)属单斜晶系, 空间群为P21/a, a=0.9833(3), b=1.8646(3),c=0.9449(1)nm, Z=2, 最终因子Rw=0.057。利用热重分析对配合物晶体两步热分解过程进行了非等温热力学研究, 探讨了反应的可能机理, 得到其相应的动力学参数。第一步非等温动力学方程为: dα/dt=A.exp(-E/RT).2(1-α)^1^/^2, 第二步: dα/dt=A.exp(-E/RT).3/2(1-α)[-ln(1-α)]^1^/^3。     

三水和硝酸N,N,N"'-四[(1'-苄基-2'-苯并咪唑)甲基]-1,2- 环已二胺合Zn(Ⅱ)的晶体结构和非等温热分解反应动力学

本文报道标题Zn(Ⅱ)配合物:[Zn(NBOCTB)](NO~3)~2.3H~2O的制备,晶体结构及热分解动力学,该晶体属三斜晶系,空间群PI,a=1.4146(2),B=1.5407(3),c=1.8518(4)nm;α=62.09(2).β=72.46(2),68.60(1)°. 并对配合物第一和第二步热分解反应进行了非等温动力学研究.运用Achar法与Coats-Redfern 法对非等温动力学数据进行分析,推断第一步脱水过程为成核生长机理,其动力学方程为d α/dt=Ae^-^E^/^R^T.3/2(1-α).[-ln(1-α) ] ^1^/^3; 动力学补偿效应表达式lnA= 0.3739E- 3. 321. 第二步分解过程为二级化学反应, 其动力学方程为:dα/dt=Ae^E^/^r^t(1-α)^2;动力学补偿效应表达式为lnA=0.2100E-3.690.     

Thermal stability and kinetic studies of new dinuclear copper(II) complexes with octaazamacrocyclic and multidonor bidentate ligands

The thermal properties of four copper(II) complexes with N,N′,N″,N-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (tpmc) and several bidentate ligands N,S (thiosemicarbazide and thiourea) or N,O donors (semicarbazide and urea), of the general formula [Cu₂(X)tpmc](ClO₄)₄, have been investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC). The thermal stability order can be recognized for the examined complexes, depending on coordinated bidentate bridging N,S or N,O ligand. Kinetic data demonstrated first-order thermal decomposition. A plausible mechanism has been proposed which explains the major products of the degradation.     

钐-邻硝基苯甲酸与1，10-邻菲咯啉配合物的热分解动力学

The complex of Sm₂(o-NBA)₆(PHEN)₂ (o-NBA, o-Nitrobenzoate; PHEN, 1,10-phenanthroline) was prepar-ed and characterized by elemental analysis, IR and UV spectraoscopy. The thermal decomposition mechanism of Sm₂(o-NBA)₆(PHEN)₂ was studied under a static air atmosphere by TG-DTG. The thermal decomposition kinetics of the complex for the first stage was studied under non-isothermal condition. The most probable mechanism functions of the thermal decomposition reaction for the first stage are: G(α)=[-ln(1-α)]^1/2, f(α)=2(1-α)[-ln(1-α)]^1/2. The activation energy E for the first stage is 259.50 kJ·mol^-1, the pre-exponential factor A is 36.19×10¹⁸ min^-1. The lifetime equation at weight-loss of 10% was deduced as lnτ=-36.70+27 572.12/T by isothermal thermogravimetric analysis.     

Mechanism of thermal decomposition of thiourea derivatives

The thermal decomposition of a series of compounds has been studied by thermogravimetry, mass spectrometry, nuclear magnetic resonance and elemental analysis. The combined use of mass spectrometry and thermogravimetry (MS and TG) in the analysis of these compounds has allowed characterization of the fragmentation pattern which was the objective of this research. The gaseous products, volatile condensed products and solid residues were identified by NMR and MS. Based on the product of thermal decomposition, the mechanism of thermal decomposition has been derived.