Researches on Thermal Decomposition Kinetics of Composite Modified Double-base Propellants

The thermal decomposition kinetics of composite modified double‐base (CMDB) propellants with a series of contents of hexogeon (RDX) was investigated by using parameters of T_eo, T_i, T_p, T_f, T_b, T_a, E, lg A and ΔH, which were obtained from using a CDR‐4P differential scanning calorimeter (DSC) and Perkin‐Elmer Pyris 1 thermogravimetric analyzer (TG) analyses with heating rates of 5, 10, 15 and 20 K/min. Reliable activation energy was calculated using Flynn‐Wall‐Ozawa method before analyzing the thermal decomposition mechanism. TG‐DTG curves were treated with Malek method in order to obtain the reaction mechanisms. The obtained results show that the thermal decomposition mechanisms with the conversion from 0.2 to 0.4 was f(α)?1/2α, and with the conversion from 0.5 to 0.7 was f(α)?(1/4)(1?α)[?ln(1?α)]^?3.     

Thermal Decomposition and Melting of A New Carboxyindole Derivative

GV150526A is a novel 2-carboxyindole derivative, recently synthesized by GlaxoWellcome, which is used in treatment or prevention of CNS disorders resulting from neurotoxic damage. It has been prepared in three forms, F1, F2 and F3, having significantly different hydration/dehydration behavior and/or diffraction patterns. Here, we extend the thermal analysis of these polymorphs above 200°C, where all forms are fully dehydrated and the main thermal phenomena are decomposition and melting. Simultaneous TG/DSC measurements have been repeated in wet and dry nitrogen atmospheres over a wide range of heating rates. Form F3 displays a qualitatively different behavior relative to F1 and F2. This fact is interpreted as an evidence of a mechanism of decomposition which sets F3 apart from F1 andF2. The thermal data are summarized by simple heuristic equations and few ‘apparent’enthalpies. This revised version was published online in August 2006 with corrections to the Cover Date.     

2，4，6-三硝基间苯二酚钡一水化合物的热分解动力学(英)

0IntroductionBarium2,4,6鄄trinitroresorecinatemonohydrate,Ba(TNR)·H2O,hasgooddetonatingpropertiesandissensitivetoflame.Itcanbeusedasinitiatingagent,igniterpowderordelaypowder.Itspreparation[1],pro鄄perties[1],crystalstructure[1]andthermalbehavior[2]haveb…     

Thermal Decomposition of Triazine Herbicides II. 6-Chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine (atrazine) and its metabolites

Thermal degradation of atrazine and its metabolites has been investigated using a thermogravimetric technique(TG) with the application of three types of crucibles: opened, Knudsen type and labyrinthtype, and non-isothermal DSC method, using hermetically closed and opened alumina sample pans. The great influence of decomposition conditions (the crucible type) on thermal degradation was observed. TG analysis showed that the degradation process of atrazine took place in three stages. The increase of amino groups in triazine ring increases the amount of non-volatile thermal degradation products by association. The presence of chlorine substituent facilitates the forming of products with low volatility. Hydroxyatrazine decomposes only in one stage process. The dealkylation process observed in hermetical sample pans (DSC) was two-stage and in open sample pans one-stage process. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal Decomposition of Strontium and Barium Malonates

The thermal decomposition of strontium and barium malonates has been studied isothermally and non-isothermally employing simultaneous TG-DTG-DTA, DSC, XRD and IR spectroscopic techniques. DSC of these malonates has been recorded both in oxygen and nitrogen atmospheres. The decomposition is a single step process and the end product formed is carbonate. The energy of activation and frequency factor values for the decomposition of strontium malonate are 547 kJ mol⁻¹ and 10⁴¹ s⁻¹ respectively. The activation energy and frequency factor values for isothermal dehydration of barium malonate sester-hydrate are 57–111 kJ mol⁻¹ and 10⁷–10¹² s⁻¹ respectively and the corresponding values for decomposition from DSC are 499.5 kJ mol⁻¹ and 10⁴⁴ s⁻¹ respectively. The higher thermal stability of strontium malonate as compared to that of barium salt is ascribed to its being anhydrous so that decomposition proceeds without restructuring. Their thermal stabilities have also been compared with that of respective oxalate salts. This revised version was published online in July 2006 with corrections to the Cover Date.     

Influence of DSC Measurement Conditions on Kinetic Parameters of Thermal Decomposition of 2,4,6-trinitrotoluene

An autocatalytic model involving the limited solubility of volatile catalytic products was applied to the thermal decomposition of 2,4,6-trinitrotoluene. The critical supersaturation of the thermal decomposition products with the catalytic properties was higher at a low heating rate. Decrease of the sample mass led to an increased critical supersaturation of the decomposition products. This is probably a result of the greater contribution of products adsorption on the aluminium pan surface. It is presumed that the differences observed in the rate constant are connected with the uncontrolled critical supersaturation of the volatile thermal decomposition products. This revised version was published online in August 2006 with corrections to the Cover Date.     

Thermal Decomposition and Dehydration Kinetics of Tetra(piperidinium) Octamolybdate Tetrahydrate in Air

Thermal decomposition of tetra(piperidinium) octamolybdate tetrahydrate, [C₅H₁₀NH₂]₄[Mo₈O₂₆]·4H₂O, was investigated in air by means of TG‐DTG/DTA, DSC, TG‐IR and SEM. TG‐DTG/DTA curves showed that the decomposition proceeded through three well‐defined steps with DTA peaks closely corresponding to mass loss obtained. Kinetics analysis of its dehydration step was performed under non‐isothermal conditions. The dehydration activation energy was calculated through Friedman and Flynn‐Wall‐Ozawa (FWO) methods, and the best‐fit dehydration kinetic model function was estimated through the multiple linear regression method. The activation energy for the dehydration step of [C₅H₁₀NH₂]₄[Mo₈O₂₆]·4H₂O was 139.7 kJ/mol. The solid particles became smaller accompanied by the thermal decomposition of the title compound.     

Influence of the Heating Rate in the Thermal Decomposition of HMX

This work refers to a study of the thermal decomposition of octahydro-1,3,5,7-tetranitro-1,3,5,7 tetrazocine (HMX) by differential scanning calorimetry (DSC) in non-isothermal conditions, with heating rates from1 to 25°C min⁻¹. The influence of the heating rate, the particle and the sample size were verified. The activation energy was calculated using the peak temperature shift method, proposed by Ozawa and a significant variation in the results was observed according to the range of the used heating rates. As the heating rate was increased, different conversions and self-heating effects were observed at the respective DSC peaks, indicating that the use of this method was inadequate and it may lead to incorrect results, which, in turn, could explain the wide range of activation energy values published in literature. At lower heating rates HMX decomposition occurs on the solid state and at higher ones decomposition occurs after melting practically at the same temperature, which does not depend on the heating rate. This revised version was published online in July 2006 with corrections to the Cover Date.     

硝酸酯的热分解性能

分别在B3LYP/6-31G*和MP2/6-31G*的理论水平下,计算得到硝酸正丙酯、硝酸异丙酯、硝酸异辛酯和二缩三乙二醇二硝酸酯4种硝酸酯的O-NO2键离解能(BDE)。 采用常压DSC和高压DSC实验方法,研究了4种硝酸酯的热分解过程,获得热分解反应动力学参数。 常压下4种物质的热分解反应发生在气相区,当压力增大至2 MPa时,4种物质直接发生液相分解反应。 4种硝酸酯的O-NO2键离解能在很大程度上符合由实验分析得到的活化能,表明4种硝酸酯的热分解反应只是单分子O-NO2键的均裂反应。     

Thermal Decomposition Kinetics of Lead 2,4,6-Trinitroresorcinate Monohydrate

IntroductionLead 2 ,4,6- trinitroresorcinate monohydrate,Pb( TNR)· H2 O,has good detonating propertiesand is sensitive to flame.It can be used as initiat-ing agent,igniter powder or delay powder.Itspreparation,properties,crystal structure[1] andthermal behavior[2 ] have been reported.In the pre-sent paper,we will report its kinetic parametersand mechanism of thermal decomposition reactionstudied with TG- DTA,IR and DSC.This is quiteuseful in the evaluation of its thermal stability un-d…     

司他夫定的热分解机理及动力学

采用TG-DTG-DSC测定司他夫定（STVD）在N2气和空气气氛中的热分解过程及其在热分解过程中不同阶段残留物的红外光谱,运用量子化学GAMESS软件计算STVD分子的键级,探讨了STVD的热分解机理。 采用Ozawa方法计算STVD各阶段热分解反应动力学参数,采用Dakin方程推算了不同使用温度下STVD的预期寿命。结果表明,STVD的热分解过程是一个三阶段过程,起始热分解步骤是联接胸腺嘧啶环与五元环的C-N键的断裂。 在N2气中,第一阶段热分解温度范围为139~173 ℃,失重21.2%,反应活化能Ea=168.9 kJ/mol,指前因子A=2.884×1019 min-1;第二阶段热分解温度范围为173~313 ℃,失重56.2%,Ea=96.4 kJ/mol,A=2.884×108 min-1;第三阶段分解速率缓慢,至880 ℃仍有10.9%残重。 在空气中,第一阶段热分解温度范围为139~166 ℃,失重19.1%,Ea=168.1 kJ/mol,A=2.188×1019 min-1;第二阶段热分解温度范围为166~314 ℃,失重53.9%,Ea=154.9 kJ/mol,A=8.913×1013 min-1;第三阶段热分解温度范围314~550 ℃,失重27%,Ea=116.9 kJ/mol,A=3.548×108 min-1。 STVD在常温下具有较好的热稳定性。     

Thermal Decomposition Kinetics of Triethylene Glycol Dinitrate

Introduction Triethylene glycol dinitrate (TEGDN) is a novel en-ergetic material containing two groups of NO2, which can be used as an energetic plasticizer ingredient in propellants because of its excellent proformance.1 It exhibits lower impact sensitivity, better thermostability, weaker poisonousness and volatility, and stronger effec-tiveness of plasticizing cellulose nitrate than nitroglyc-erine (NG). As a new plasticizer TEGDN has good ap-plication prospects in the near future. The…     

消旋卡多曲在空气中的热分解动力学

用热分析(TG/DTA/DSC)技术研究了消旋卡多曲(C₂₁H₂₁NO₄S)在空气中的热分解过程. 热分析结果表明, 消旋卡多曲在空气中一步分解, 其熔点为77.4 ℃. 用Friedman法, Flynn-Wall-Ozawa (FWO)法和ASTM E698法求取了分解过程的活化能E, 并通过多元线性回归法给出了可能的机理函数.     

2,4-二硝基咪唑铅配合物Pb(DNI)2(H2O)4的热分解

应用TG, TG-DSC-FTIR-MS联用技术和热裂解原位RSFT-IR技术研究了2,4-二硝基咪唑铅(PDNI)的热分解机理. 结果表明, PDNI在102 ℃附近脱除分子内配位水, 生成Pb(DNI)2; 在284 ℃附近C—NO2断裂, 生成NO2, 咪唑环开环, 伴随发生强烈的氧化放热反应, 生成CO2, N2O和铅盐与咪唑残余基团形成的复杂混合物或多聚烃类化合物; 在300～400 ℃范围内, PDNI继续缓慢分解, 生成CO2, N2O和Pb[NCO]2; 升温至410 ℃以上, PDNI分解生成CO和Pb[CN]2.     

Thermal Behaviour of Some Terpenoids

The terpenoids acetyl sitosterol, lupeol, acetyl diosgenin and stigmasterol were studied. Comparison of the thermogravimetric curves and the activation energies of the terpenoids suggested the following sequence of thermal stability: acetyl sitosterol < acetyl diosgenin < lupeol < stigmasterol. The DSC curves allowed determination of the melting points and the degrees of purity. Comparison of the TG and DSC curves revealed the presence of phase transitions without mass loss that were attributed to rearrangements in the terpenoid molecules. This revised version was published online in August 2006 with corrections to the Cover Date.     

ZnAc2·2H2O在空气中的热分解动力学研究

用TG/DTA,DSC和XRD技术研究了固态物质ZnAc2.2H2O在空气中的热分解过程.结果表明,ZnAc2.2H2O在空气中发生两步分解,其失重率与理论计算失重率相符.XRD结果表明,ZnAc2.2H2O分解的最终产物为ZnO.用Friedman法和Flynn-Wall-Ozawa(FWO)法求得分解过程的活化能E,并通过多元线性回归方法给出了可能的机理函数.ZnAc2.2H2O在空气中两步分解的活化能分别为119.82和66.82kJ/mol.     

Thermal Decomposition of Ammonium 3-Nitro-1,2,4-triazol-5-onate Monohydrate

The thermal decomposition of ammonium 3-nitro-1,2,4-triazol-5-onate monohydrate[NH4（NTO）·H2O] was studied by means of thermal analysis-MS coupling and the combination technique of in situ thermolysis cell with rapid-scan Fourier transform infrared spectroscopy. The results show that there are two endothermic steps and one exothermic step in the decomposition process of NH4（NTO）·H2O. The detected gas products consist of NH3, H2O, N2, CO2, CO, and NO2.     

Thermal Decomposition of Hydrated Lanthanide Picrates by TG/DTG and DSC Analyses

Hydrated lanthanide picrates with a composition of: Ln(pic)₃⋅xH₂O (Ln=La–Lu, Y) were synthesized and characterized. Thermal decomposition of the picrates by TG/DTG and DSC techniques are reported. This revised version was published online in July 2006 with corrections to the Cover Date.     

Kinetic Studies of the Thermal Decomposition of KDNBF, a Primer for Explosives

KDNBF (potassium 4,6-dinitrobenzofuroxan) has been used as a primer explosive in igniters and detonators for many years. Considerable information about the sensitivity of KDNBF to various stimuli, such as impact, friction, shock and electrostatic charge, is known. However, the thermal sensitivity of KDNBF has been relatively unexplored. Hence, there is very little information available concerning the fundamental thermal properties of KDNBF. Therefore, as part of an extensive thermal hazard assessment, DSC, TG, accelerating rate calorimetry (ARC) and heat flux calorimetry (HFC) measurements have been undertaken on KDNBF. The results demonstrate that KDNBF decomposes via a multi-step exothermic process directly from the solid state. The decomposition process does not appear to depend on the nature of the atmosphere, except in the final stage of the TG decomposition in air, where remaining carbonaceous material is converted to CO₂. The first stage of the decomposition is sufficiently rapid that ignition occurs if too large a sample is used. Dynamic and isothermal methods were used to obtain the kinetic parameters and a range of activation energies were obtained, depending on the experimental conditions. The kinetic results have been analyzed in terms of various solid state decomposition models. This revised version was published online in August 2006 with corrections to the Cover Date.     

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.