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.     

The influence of porosity of ammonium perchlorate (AP) on the thermomechanical and thermal properties of the AP/polyvinylchloride (PVC) composite propellants

The influence of porous ammonium perchlorate (P_OAP) on the thermomechanical and combustion behavior of solid rocket propellants based on polyvinylchloride binder has been investigated. Differential scanning calorimetry, differential thermogravimetry, dynamic mechanical thermal analysis, and scanning electronic microscopy measurements were used for thermomechanical and thermal decomposition properties assessment. The results obtained indicate that lower glass transitions of the propellants and catalytic effect of combustion are obtained with P_OAP.     

Tris(2‐aminoethyl)amine‐based ferrocene‐terminated dendrimers as burning rate catalysts for ammonium perchlorate‐based propellant decomposition

Ferrocene‐based derivatives show potential application as burning rate catalysts (BRCs) for solid composite propellants. However, migration problems of simple ferrocene‐based derivatives limit their application as BRCs in solid composite propellants. To overcome the migration problems of ferrocene‐based BRCs and to enhance the burning rate of ammonium perchlorate (AP)‐based propellants, zero‐ to second‐generation tris(2‐aminoethyl)amine‐based ferrocene‐terminated dendrimers (G0, G1 and G2) were synthesized. The structures of G0, G1 and G2 were confirmed using ¹H NMR, Fourier transform infrared and UV–visible spectroscopies. The electrochemical behavior of G0, G1 and G2 was investigated using cyclic voltammetry. It was found that G0, G1 and G2 showed redox behavior due to the presence of ferrocene and this redox behavior was diffusion controlled over the investigated scan range. The burning rate catalytic effect of G0, G1 and G2 on thermal decomposition of AP was investigated using thermogravimetry and differential thermogravimetry. G0, G1 and G2 showed good catalytic effect on the thermal decomposition of AP. Anti‐migration studies showed that migration of G0, G1 and G2 was much slower than that of 2,2‐bis(ethylferrocenyl)propane (catocene) and ferrocene.     

Effect of pressures on decomposition reaction kinetics of double-base propellant catalyzed with cerium citrate

The decomposition reaction kinetics of the double-base (DB) propellant (No. TG0701) composed of the mixed ester of triethyleneglycol dinitrate (TEGDN) and nitroglycerin (NG) and nitrocellulose (NC) with cerium(III) citrate (CIT-Ce) as a combustion catalyst was investigated by high-pressure differential scanning calorimetry (PDSC) under flowing nitrogen gas conditions. The results show that pressure (2 MPa) can decrease the peak temperature and increase the decomposition heat, and also can change the mechanism function of the exothermal decomposition reaction of the DB gun propellant under 0.1 MPa; CIT-Ce can decrease the apparent activation energy of the DB gun propellant by about 35 kJ mol⁻¹ under low pressure, but it can not display the effect under high pressure; CIT-Ce can not change the decomposition reaction mechanism function under a pressure.     

Thermal analysis of two series <Emphasis Type="Italic">mono</Emphasis>- and <Emphasis Type="Italic">di</Emphasis>-azocalix[4]arene derivatives

In the present study, thermal decomposition of mono- and di-azocalix[4]arene derivatives (A1–A8 and B1–B8) was investigated by means of thermogravimetry (TG), differential thermal analysis (DTA) and derivative thermogravimetry (DTG). The exclusion of methanol, hydrolysis of benzoyl ester and methyl ketone groups in lower rim, and decomposition of azo groups in upper rim have occurred during thermal analysis, consecutively. The thermal decomposition degrees amount of volatile pyrolysis products were determined in air atmosphere using TG, DTA and DTG curves. In conclusion, the thermal analyses of azocalix[4]arenes demonstrated that its stability depends on the substituted groups and their positions in the calix[4]arene structure.     

Synthesis of Ferrocene-based Esters as Burning Rate Catalysts and their Anti-migration Study

Ferrocene-based (Fc-based) burning rate catalysts (BRCs) play an essential role in the solid rocket propellants. However, the migration problem during curing and storage limits their applications. To retard the migration problems of Fc-based BRCs and to increase the burning rate (BR) of AP-based propellants, Fc-based esters compounds (Es-Fcs) were synthesized. The synthesized Es-Fcs were characterized by X-ray diffraction, proton nuclear magnetic resonance (¹H NMR),¹³C NMR and Fourier transform infrared (FT-IR) spectroscopy. The electrochemical behaviors of Es-Fcs were investigated by cyclic voltammetry (CV). The BR catalytic activity of Es-Fcs on thermal decomposition of AP were examined by thermogravimetry (TG). Thermal analysis results showed that these Es-Fcs had good BR catalytic effects on thermal decomposition of AP. It was found that the anti-migration performance of Es-Fcs were better than catocene and Fc.     

Influences of aging on thermal decomposition mechanism of high performance oxidizer ammonium dinitramide

Ammonium dinitramide (ADN) is one of the several promising new solid propellant oxidizers. ADN is of interest because its oxygen balance and energy content are high, and it also halogen-free. One of the most important characteristics of a propellant oxidizer, however, is stability and ADN is known to degrade to ammonium nitrate (AN) during storage, which will affect its performance. This study focused on the effects of aging on the thermal decomposition mechanism of ADN. The thermal behaviors of ADN and ADN/AN mixtures were studied, as were the gases evolved during their decomposition, using differential scanning calorimetry (DSC), thermogravimetry–differential thermal analysis-infrared spectrometry (TG–DTA-IR), and thermogravimetry–differential thermal analysis-mass spectrometry (TG–DTA-MS). The results of these analyses demonstrated that the decomposition of ADN occurs via a series of distinct stages in the condensed phase. The gases evolved from ADN decomposition were N₂O, NO₂, N₂, and H₂O. In contrast, ADN mixed with AN (to simulate aging) did not exhibit the same initial reaction. We conclude that aging inhibits early stage, low temperature decomposition reactions of ADN. Two possible reasons were proposed, these being either a decrease in the acidity of the material due to the presence of AN, or inhibition of the acidic dissociation of dinitramic acid by NO ₃ ^? .     

Thermal decomposition mechanism of tenofovir disoproxil fumarate

Tenofovir disoproxil fumarate (TDF) is an antiretroviral medication widely used to prevent and treat HIV/AIDS and to treat chronic hepatitis B. In this paper, thermal decomposition processes of TDF were measured with thermogravimetry, differential scanning calorimetry and thermogravimetric analysis coupled with Fourier transform infrared spectroscopy. The IR spectra, high-performance liquid chromatography and liquid chromatography mass spectrometry of TDF and the residues of its thermal decomposition at various temperatures were determined. The molecular bond orders were calculated using an ab initio method from the GAMESS program of quantum chemistry. The mechanism of thermal decomposition was discussed. The results indicated that the thermal decomposition of TDF is a three-step process, the initial step of thermal decomposition of TDF is the decomposition of carboxylic ester, the first stage mainly is the decomposition of the phosphoric disoproxil section, and the second stage mainly is the decomposition of the tenofovir section and partially goes through adenine stage. The initial decomposition temperature in either nitrogen or air is 138 °C, and the thermal stability of TDF is not very good under routine temperature.

     

Thermochemistry of some complexes of chromium(III) with imidazoles

The thermal decomposition in air of several complexes of chromium(III) with imidazole,N-methylimidazole and 2-methylimidazole has been studied with the aid of differential thermal analysis (DTA), thermogravimetry (TG) and derivative thermogravimetry (DTG) in the temperature range 25–600°C. Although the final process of the decomposition gives Cr₂O₃, there are interesting differences in the complete process of decomposition. The reasons for these differences appear to be related to the trans-effect and to the presence in the imidazole complexes of hydrogen bonds. Enthalpies of the several decomposition reactions have been determined by differential thermal analysis.     

Effect of iron-containing catalysts on thermal decomposition of cured GAP-AP propellants

The effects of various burning rate catalysts on thermal decomposition of cured glycidyl azide polymer (GAP)-ammonium perchlorate (AP) propellants have been studied by means of thermal analysis and a modified vacuum stability test (MVST). Four types of iron-containing catalysts examined in this paper are catocene, ferrocenecarboxaldehyde (FCA), ferrocene, and ferric oxide. Results of differential thermal analysis (DTA) and thermogravimetric analysis (TG) revealed that the catalysts play an important role in the decomposition of both AP and GAP. The peak decomposition temperature (T _m) of DTA curves and onset decomposition temperature (T _o) of TG patterns considerably shifted to a lower temperature as the concentration of catalysts increased in the propellants. The endothermic temperature of AP, however, is unaffected by the presence of burning rate catalysts in all cases. The activation energy of decomposition of the propellants in range of 80 to 120°C is determined, based on the MVST results.     

Thermal behavior and decomposition kinetics of composite solid propellants in the presence of amide burning rate suppressants

The employment of burning rate suppressants in the solid rocket propellant formulation is long known. Different research activities have been conducted to well understand the mechanism of suppression, but literature about the action of oxamide (OXA) and azodicarbonamide (ADA) on the thermal decomposition of composite propellant is still scarce. The focus of this study is on investigating the effect of burning rate suppressants on the thermal behavior and decomposition kinetics of composite solid propellants. Thermogravimetric analysis (TG) and differential thermal analysis have been used to identify the changes in the thermal and kinetic behaviors of coolant-based propellants. Two main decomposition stages were observed. It was found that OXA played an inhibition effect on both stages, whereas the ADA acts as a catalyst in the first stage and as coolant in the second one. The activation energy dependent on the conversion rate was estimated by two model-free integral methods: Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO) based on the TG data obtained at different heating rates. The mechanism of action of coolants on the decomposition of solid propellants was confirmed by the kinetic investigation as well.     

Synthesis and catalytic performance of ferrocene‐based compounds as burning rate catalysts

To overcome migration problems of ferrocene‐based burning rate catalysts and to enhance burning rate of ammonium perchlorate (AP)‐based propellants, eleven ferrocene‐based compounds ( 1 – 11 ) were synthesized by the condensation reaction of ferrocenecarbonyl chloride with corresponding amines and alcohols. The synthesis of 1 – 11 was confirmed using ¹H NMR, Fourier transform infrared and UV–visible spectroscopy. Their electrochemical properties were analyzed using cyclic voltammetry. The compounds showed redox behavior due to the presence of ferrocene. Their catalytic behavior in the thermal decomposition of AP was investigated using thermogravimetry (TG) and differential TG (DTG). In the presence of 5 wt% 1 – 11 , the thermal decomposition temperature of AP was significantly decreased. TG and DTG analyses showed that 1 – 11 had a good catalytic effect in the thermal decomposition of AP. Anti‐migration studies showed that migration of 1 – 11 was slower than that of 2,2‐bis(ethylferrocenyl)propane (catocene) and ferrocene. The effect of the presence of polar elements like oxygen and nitrogen on anti‐migration behavior of small ferrocene‐based compounds was also investigated. Oxygen‐containing compounds showed better anti‐migration behavior than nitrogen‐containing compounds.     

The thermal decomposition behavior of RDX-base propellants

In this paper, the thermal decomposition of cyclotrimethylenetri-nitramine (RDX)-base propellants involving many components has been investigated by differential scanning calorimeter (DSC). The decomposition characters at different heating rates and the activation energies are determined by DSC measurement. The results show that the decomposition of RDX is accelerated obviously during the decomposition of nitroglycerin (NG). Though the content of dibutyl-benzene-dicarbonate (DBP) ingredient in the propellants is less, it has a remarkable effect on the initial decomposition temperature of the propellants. The azido-nitromine compound (DIANP) brings about the shift of the peak of decomposition of RDX and nitrocellulose (NC) to lower temperature due to its liquefying or dissolving.     

Study of some volatile compounds evolved from the thermal decomposition of atenolol

Simultaneous thermogravimetry–differential scanning calorimetry (TG–DSC) and coupled thermogravimetry–infrared spectroscopy (TG–FTIR) analyses were used to study the antihypertensive drug atenolol. The TG–DSC curves provided information concerning the thermal stability and decomposition profiles of the compound. From the TG–FTIR coupled techniques, it was possible to identify ammonia and isopropylamine as possible volatile compounds released during the thermal decomposition of the drug.     

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)&#8226; (1－α)2.12.     

Thermal decompositions of some divalent transition metal complexes of triethanolamine

The thermal behaviours of the Ti(II), Mn(II), Fe(II), Ni(II), Cu(II) and Zn(II) complexes of triethanolamine were studied by means of thermogravimetry, differential thermogravimetry, differential thermal analysis infrared spectrophotometry and elemental analysis. The sequence of thermal stability of the metal complexes, determined by using the initial decomposition temperature, was found to be Ti(II)?Mn(II)>Fe(II)>Ni(II)>Zn(II)>Cu(II). Some of the kinetic parameters, such as the activation energy and order of reaction for the initial decomposition reaction, were calculated and the relationship between the thermal stability and the chemical structure of the complexes is discussed.     

甲磺酸帕珠沙星的热分解机理及动力学

采用热重(TG)和差示扫描量热(DSC)法测定了甲磺酸帕珠沙星(PZFX)在氮气氛和空气氛中的热分解过程,测定了PZFX及其在热分解过程中不同阶段残余物的红外光谱,运用量子化学GAMESS软件计算了PZFX分子的键级,推断了PZFX的热分解机理.结果表明PZFX的热分解过程的起始步骤是甲磺酸的分解.采用Ozawa方法计...     

Thermal analysis of N-phenylbenzohydroxamic acid (PBHA)

The thermal dissociation of N-phenylbenzohydroxamic acid was studied by differential thermal analysis (DTA) and thermogravimetry (TG). The DTA curve showed two exothermic peaks caused by melting and/or decomposition of the compound.     

Etude sur le comportement thermique de quelques polymeres ignifugeants contenant du phosphore et des halogenes

The thermal behaviour a series of polyphosphonates was studied by thermogravimetry (TG) and differential thermal analysis (DTA). The obtained data permitted the calculation of activation energies and reaction orders on decomposition zones by the Coats — Redfern method.     

Study on the thermal decomposition of famciclovir

Journal of Thermal Analysis and Calorimetry - The thermal decomposition of famciclovir (FCV) was measured with thermogravimetry, differential scanning calorimetry, and thermogravimetric analysis...