The Thermal Decomposition of some Dialkyl Dicarbanilates

The thermal decomposition at 300 C of five dicarbanilates derived from 4,4 '— diphenylmethane diisocyanate (MDI) was studied in an attempt to elucidate the low-temperature decomposition mechanism of rigid MDI-based polyurethane foams. The dicarbanilates of primary and secondary alcohols decomposed via normal fission of the urethane linkages, whereas those of tertiary alcohols yielded 4,4′—diphenylmethane diamine (MDA), carbon dioxide and the appropriate olefin via abnormal fission of the carbanilates.     

RDX热分解研究

为了更加全面的探究黑索今(RDX)热安全性,利用绝热加热法及DSC-TG-DTG法两种实验方法分析了RDX的热分解过程。通过对比两种实验方法可以总结出RDX在密闭条件下热分解初始速度比在开放系统中低5.4℃,实验条件对分解过程及相关参数影响较大。     

Thermal Decomposition of Sodalites

The decomposition of bromate and hydroxide sodalites was studied by DTA and TG. Bromate sodalite is converted exothermally at 600°C into bromide sodalite. Hydroxide sodalite loses water and is then converted endothermally into a carnegieite phase at 740°C. The conversion of hydroxide sodalite mixed with sodium halide into halide sodalite at temperatures >740°C proceeds via the decomposition of the hydroxide sodalite. After hydroxide sodalite is heated to temperatures between 600°C and the conversion temperature, it exhibits the photoluminescence of O₂⁻.     

Thermal Decomposition of Aminonitrobenzodifuroxan

In this study, the thermal decomposition properties of aminonitrobenzodifuroxan are studied using a differential scanning calorimeter (DSC), a thermogravimeter (TG), an X‐ray diffractometer, a mass spectrometer (MS), and a Fourier transform infrared spectrometer (FTIR). The results demonstrate that aminonitrobenzodifuroxan undergoes thermal decomposition in the solid state. Under elevated temperatures, the decomposition primarily involves two steps: separation of nitro group and ring‐scission of the furoxan circles at 198.1 °C, and decomposition of the relatively stable residues (benzofuroxan circle) at 199.1 °C. Moreover, it is found that among the products, nitrogen dioxide undergoes oxidation and catalysis on the host molecule during the whole decomposition. Based on Kissinger and Ozawa functions, we deduce that the activation energies of these two reactions are 167.68 and 204.55 kJ mol⁻¹, respectively. The released energy (ΔH) of CL‐18 is −1781.8 J g⁻¹.     

水胶炸药的热分解动力学

为研究水胶炸药的热分解特性及化学动力学参数,用非等温热失重(TG)和差热扫描(DSC)联用仪,在2.5、5.0、10.0、20.0、40.0K/min的线性升温速率下,测试了岩石水胶炸药和煤矿许用水胶炸药热分解的起始温度和峰顶温度.用Ozawa法和Kissinger法计算了水胶炸药受热分解的化学动力学参数,得到120、150和250℃时的反应速率常数,计算了等动力学温度点.结果表明,煤矿许用水胶炸药热安定性好于岩石水胶炸药.     

NEPE推进剂的热分解研究(Ⅲ)HMX/RDX/AP-NEPE推进剂的热分解

采用快速热裂解原位反应池(气体原位反应池)／快速扫描傅里叶变换红外光谱仪(RSFT-IR)和固体原位池/RSFT—IR联用技术，实时测定了HMX／RDX／AP—NEPE推进剂气相及凝聚相热裂解产物，获得了在线性升温条件下该推进剂的热分解特征。研究表明，AP对其热分解过程有明显的催化作用。     

RDX和HMX的热分解III.分解机理

简述RDX和HM X热分解的各种机理,其热分解的初始过程是N-N和C-N键断裂的竞争反应,试验条件和样品相态等因素影响竞争过程。用DSC-FT IR联用技术和热裂解原位池/FT IR分析了主要分解气相产物和凝聚相中主要官能团的变化。结果表明,RDX和HM X热分解的主要分解气相产物为N2O,CH2O,CO,CO2,H2O和HCN。RDX的分解气相产物CH2O和H2O红外吸收率的温度关系曲线都产生双峰,RDX基团-NNO2的吸收带1 589 cm-1和1 278 cm-1有两个不同速率的变化过程。用N-N键和C-N键竞争断裂的观点解释了RDX与HM X热分析和产物分析的结果。     

氧氟沙星的热稳定性及其热分解动力学

测定了在氮气气氛中第三代氟喹诺酮类药物氧氟沙星(OFLX)的热稳定性。用差示扫描量热法(DSC)、热重法(TG)和微分热重法(DTG),研究了药物氧氟沙星的热分解动力学。计算了动力学参数E、n、A,并结合量子有机化学计算的键长、原子静电荷参数研究了热分解机理,推断了热分解机理及药品贮存期。用热分析研究固体药物的热分解过程方法简便,结果可行。     

Thermal Decomposition of Guanidinium Perchlorate

Thermal decomposition of guanidinium perchlorate has been studied by thermogravimetry, differential thermal analysis, mass spectrometry and X-ray diffractometry. The title compound undergoes crystallographic phase transformation at 180°C before melting at 255°C. It decomposes exothermally into gaseous products in the temperature range 275°C–325°C. The mass spectral results suggest that the compound undergoes thermal decomposition into neutral particles which are then vapourized, ionized and oxidized. The fragment cyanamide is found to undergo trimerization to give melamine.     

Thermal Decomposition of Pentaerythritol Tetranitrate

A chemical kinetic model for the thermal decomposition of the solid high explosive pentaerythritol tetranitrate (PETN) is developed for prediction of times to thermal explosion using the Chemical TOPAZ heat transfer computer code. The model is based on times to thermal explosion measured in a new One Dimensional Time to Explosion (ODTX) apparatus. ODTX experiments are reported for pure PETN and for Semtex 1A. The pure PETN results are accurately modeled using a four reaction decomposition process in which an autocatalytic process produces intermediate reaction product gases, which subsequently react in a second order gas phase process to produce the final reaction products. Semtex 1A exhibits longer times to explosion than PETN at low temperatures, indicating that its endothermic binder decomposition absorbs heat produced by PETN decomposition. This binder reaction is modeled as a first order endothermic process. Three experiments on 5.08 cm diameter unconfined cylinders of PETN ramp heated to explosion at different rates are reported. The PETN model accurately predicts the thermocouple records and explosion times for these unconfined experiments in which only intermediate gaseous products can form.     

PYX的热分解特性

用热重-微商热重分析(TG/DTG)、热重与傅里叶变换红外联用技术(TG/FITR)、热重与质谱联用(TG/MS)和热裂解快速扫描傅里叶变换红外技术(RSC/FTIR)研究了PYX(2,6-二苦氨基-3,5-二硝基吡啶)热分解过程.结果表明,PYX的热分解分为两个阶段,第一阶段存在位于-NH-基对位的硝基(C-NO2)异构化为亚硝基(C-ONO)、位于-NH-基邻位的-NO2与之发生环化反应,释放NO和形成芳香多聚化合物;第二阶段为芳香多聚化合物的热分解,释放出HCN,CO,CO2和H2O等气体.     

Thermal Decomposition of Azide Polymers

Thermal decomposition of polyglycidyl azide (GAP) and bis(azidomethyl)oxetane/tetrahydrofuran copolymer (BAMO/THF) was studied by TGA and DSC in helium atmosphere, which was showing overall first-order kinetics. The additional azide groups at terminal position in the molecular structure decomposed independently and increased the rate of decomposition. However, the decomposition kinetics was less affected by the additional azide groups in the main chain. The decomposition properties of aged polymer Samples were the same as those of untreated ones. Catocene significantly altered the decomposition temperatures of GAP and BAMO/THF. The speak temperature of DSC thermogram changed from 533 K to 494 K in GAP and from 535 K to 498 K in BAMO/THF. Like UV treatment, BAMO/THF with catocene was thermally cross-linked during the aging at 343 K. Although BAMO/THF with catocene produced rubbery solids from the initial viscous liquids, there was no significant difference between the rate of decomposition of treated sample and that of untreated one.     

Thermal Decomposition of Lead Carbonate

The thermal decomposition of PbCO₃ powder was measured at low eating rates under controlled pressures of CO. The solid phases formed by three stages of decomposition were found to be PbO.PbCO₃, 2PbO.PbCO₃, and PbO, in the order of increasing temperature. For each reaction a log p versus l/T plot of the data resulted in a straight line.     

Thermal Decomposition of Tetraethylammonium Perchlorate

Thermal decomposition of tetraethylammonium perchlorate has been studied by thermogravimetry, differential thermal analysis and mass spectrometry. The title compound undergoes crystallographic transformation at 98°C and explodes at 298°C. The heat of phase transformation is calculated to be 2.5 kcal/mol. The mass spectral data suggest that the salt undergoes thermal decomposition into neutral particles which are then vapourized and ionized as well as oxidized.     

Thermal Decomposition of BAMO Copolymers

The effects of copolymerization of THF, as an inert component, AMMO, as an energetic one and NMMO, as a nitrate ester, with BAMO on their thermal decomposition are reported here. Although the thermal decomposition of the BAMO and NMMO units in B/N(7/3) carry out independently and the heat generated by the NMMO unit decomposition accelerates the BAMO unit decomposition, the THF and AMMO units do not affect that of the BAMO unit in B/T(7/3) and B/A(7/3). One exothermic peak in DSC is shown for B/A(7/3) and B/T(7/3) except for B/N(7/3) which shows two peaks. One peak at lower temperature is from the NMMO unit decomposition and the other is from the BAMO unit. The rate of decomposition of B/A(7/3) is the same as that of poly(BAMO), which indicates that the reactivity of the AMMO unit is equal to that of the BAMO unit. In propellant, containing 75% HMX and 25% copolymer binder, burning rate of B/A(7/3)/HMX is faster than that of B/N(7/3)/HMX. Although the heat of decomposition for B/A(7/3) in DSC is smaller than that for B/N(7/3), that of B/A(7/3)/HMX is larger than that of B/N(7/3)/HMX. The reaction occurred in the condensed phase of the propellant, therefore, may play an important role in the combustion.     

Thermal Decomposition Process of HMX

The thermal decomposition of HMX has been investigated using thermoanalytical techniques and infrared spectroscopic study at both above and below its melting point. The weight loss phenomenon that occurs as the temperature is elevated at a constant heating rate has been clearly separated into four elementary processes which are induction period, sublimation, first order solid phase reaction, and highly exothermic liquid phase reaction by plotting them against the logarithm of the heating rate versus the reciprocal temperature. Hydroxymethyl formamide has been shown to be a major product of the liquid phase decomposition, which suggests that the decomposition of HMX in the liquid phase should be initiated by the N-N bond scission but not by the C-N bond scission.     

Thermal Decomposition of Europium Hydroxide

The thermal decomposition of europium hydroxide in an air atmosphere was investigated by means of weight-loss measurements, infrared spectroscopy, X-ray diffraction analysis, and electron microscopy. These studies showed that EU(OH)° decomposed at temperatures between 225° and 300°C into EuOOH, which was stable up to about 425°C. Between 435° and 465°C this compound decomposed into cubic Eu₂O₃, which was stable until its inversion to the high-temperature monoclinic form. X-ray diffraction data were collected for Eu(OH)₃ and EuOOH and showed that the trihydroxide has a hexagonal crystal structure and the oxyhydroxide is possibly orthorhombic. The Eu(OH)₂, EuOOH, and cubic EunOa powders contained particles up to several microns in size consisting of agglomerates of crystallites in the size range 200 to 400 A. The single monoclinic Eu₂O₃ sample studied contained crystallites whose average size was greater than 2000 A.     

Thermal Decomposition of Triaminoguanidinium Nitrate

The kinetics of thermal decomposition of triaminoguanidinium nitrate (TAGN) was studied for the solid and liquid (solution) states of aggregation. The decomposition of crystalline powdered TAGN develops with severe self-acceleration. Its formal kinetic characteristics are determined. The main cause of the acceleration is the progressive melting of the solid during its thermal decomposition. The decomposition of TAGN in solution is severalfold faster than that in the solid state and proceeds at a rate decreasing with time. The main gaseous products of TAGN decomposition are N₂, N₂O, and H₂O. The chemistry of the processes involved in TAGN decomposition are discussed. Key words: thermal decomposition, triaminoguanidinium nitrate, oxidizer.     

驱虫剂左旋咪唑的热稳定性研究

分析固体噻唑类驱虫药物左旋咪唑的热分解过程。采用热重分析与差示扫描量热分析方法,研究丁药物左旋咪唑的热分解动力学,计算了热分解动力学参数E、A、γ;并结合量子化学计算的有机物结构的键长、原子静电荷研究了热分解机理,推断了热分解机理和产物及贮藏期。用热分析研究固体药物左旋咪唑的热分解过程方法简便,结果可靠。     

高氯酸[四氨·双(5-硝基四唑)]合钴(Ⅲ)的热分解性能

利用DSC法研究了高氯酸[四氨·双(5-硝基四唑)]合钴(Ⅲ)(BNCP)的热分解性能,并与苯并三氧化呋咱(BTF)和超细六硝基艹氐(HNS-Ⅳ)的热分解性能进行了比较,用Kissinger法和Ozawa法得到了BNCP、BTF、HNS-Ⅳ热分解反应动力学参数.在10 ℃/min的升温速率下,BNCP的分解峰温为289.6 ℃,比BTF高25.4 ℃,其分解热焓在3者中最大.VST、TG研究表明,BNCP在100 ℃以下具有良好的热安定性.Kissinger法得到的BNCP分解表观活化能为178.3 kJ/mol,比BTF和 HNS-Ⅳ分别低46.4 kJ/mol和43.1 kJ/mol;而用Ozawa法得到的BNCP分解表观活化能为187.5 kJ/mol,比BTF和HNS-Ⅳ分别低约33.8、32.8 kJ/mol.