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1.
AP/HTPB based composite
propellants with additives such as ammonium oxalate (AO), mixture of ammonium
oxalate and strontium carbonate (SC) was investigated by burning rate, TG-DTG
and FTIR experiments. The results show that the burning rates of these propellants
are decreased significantly. TG-DTG experiments indicate that decomposition
temperatures of AP with these additives are increased. Furthermore, the activation
energy of the decomposition reaction of AP is also increased in the presence
of AO or AO/SC. These results show that AO or AO/SC restrains the decomposition
of AP. The burning rates of these propellants are decreased. The burning rate
temperature sensitivity of AP/HTPB based propellants is reduced significantly
by the addition of AO or AO/SC. But the effect of AO is less than that of
AO/SC. AO/SC is better effect to reduce temperature sensitivity and at the
same time, to reduce pressure exponent. The reduced heat release at the burning
surface of AP/HTPB/AO is responsible for the reduced temperature sensitivity.
Synergetic action is probably produced between AO and SC within AP/HTPB based
propellants in the pressure range tested. This synergetic effect causes the
heat release to reduce and the burning surface temperature to increase. Moreover,
it makes the net exothermal reaction of condensed phase become little dependent
on T
0. Thus, the
burning rate temperature sensitivity is reduced. 相似文献
2.
3.
Abbas Eslami Seyed Ghorban Hosseini Masomeh Bazrgary 《Journal of Thermal Analysis and Calorimetry》2013,113(2):721-730
This research aimed to investigate the optimum conditions for modification of thermal decomposition properties of ammonium perchlorate (AP) particles through microencapsulation techniques. A solvent/non-solvent method has been used to perform microencapsulation of AP particles with some polymer-coating agents such as viton A and nitrocellulose (NC). Differential scanning calorimetry, thermogravimetry, and scanning electron microscopy have been exploited to investigate the thermal properties, heat of decomposition, and coating morphology of pure and coated samples. The preliminary results revealed that AP microparticle could be effectively coated with both NC and viton, but the latter significantly and unfavorably attenuated heat of decomposition of AP so NC was chosen as an appropriate coating agent for modification of thermal properties of AP. The thermal analysis of NC-coated samples, prepared at optimized coating conditions, showed that its first stage decomposition temperature increases about 12 °C with respect to uncoated sample and reaches to 305 °C. Also, the apparent activation energy (E), ΔG ≠, ΔH ≠, and ΔS ≠ of the decomposition processes of the pure and coated AP particles at the optimum conditions were obtained by non-isothermal methods that proposed by ASTM and Ozawa. Finally, the results of this investigation showed that microencapsulation of AP particles with fibrous NC enhance its heat of decomposition (~120 J g?1) with no obvious effect on kinetic parameters and thermal decomposition temperature. 相似文献
4.
Y. H. Ren F. Q. Zhao J. H. Yi K. Z. Xu H. X. Ma R. Z. Hu J. R. Song 《Journal of the Iranian Chemical Society》2012,9(3):407-414
A new ionic compound (3-ATz)+ (NTO)?C was synthesized by the reaction of 3-amino-1,2,4-triazole (3-ATz) with 3-nitro-1,2,4-triazol-5-one (NTO) in ethanol. The single crystals suitable for X-ray diffraction measurement were obtained by crystallization at room temperature. The crystal is monoclinic, space group p 2(1)/c with crystal parameters of a?=?0.6519(2)?nm, b?=?1.9075(7)?nm, c?=?0.6766(2)?nm, ???=?94.236(4)°, R 1?=?0.0305 and wR 2?=?0.0789. The thermal behaviors were studied, and the apparent activation energy and pre-exponential constant of the exothermic decomposition stage were obtained by Kissinger??s method and Ozawa??s method. The self-accelerating decomposition temperature is 505.40?K, and the critical temperature of the thermal explosion is obtained as 524.90?K. The specific heat capacity was determined with Micro-DSC method and the theoretical calculation method, and the standard molar specific heat capacity is 221.31?J?mol?1?K?1 at 298.15?K. The Gibbs free energy of activation, enthalpy of activation, and entropy of activation are 151.55?kJ?mol?1, 214.52?kJ?mol?1 and 122.44?J?mol?1?K?1. The adiabatic time-to-explosion of the compound was estimated to be a certain value between 5.0 and 5.2?s, and the detonation velocity (D) and pressure (P) were also estimated using the nitrogen equivalent equation according to the experimental density. 相似文献
5.
Maryam Sa'at Masoud Yarmohammadi Mona Zamani Pedram Mansour Shahidzadeh Mohammad Sadegh Amini-Fazl 《国际化学动力学杂志》2019,51(5):337-345
A novel nanocomposite catalyst for thermal degradation of the ammonium perchlorate (AP) has been synthesized, and its effect on the thermal behavior of AP has been investigated. Preparation of the catalyst was carried out via functionalization of the graphene oxide with phenyl isocyanate and its noncovalent bonding to catocene. The catalytic activity of the catalyst was studied by thermal gravimetric analysis/differential scanning calorimetry at various heating rates. In addition, the effect of the catalyst on the AP thermal decomposition has been investigated by Kissinger and Friedman methods as two model-free methods for calculation of the activation energy parameter. According to the Kissinger method calculations, the Ea of AP decomposition reduced about 151 kJ⋅mol−1 lower than the reported value for pure AP in the presence of the catalyst. Calculation of the Ea value for various reaction conversion rates by the Friedman method also confirmed the Kissinger method results. 相似文献
6.
Evaluation of the 3-hydroxy pyridine antioxidant effect on the thermal-oxidative degradation of HTPB
The effect of the mixture of two antioxidants has been evaluated on the thermal-oxidant degradation of the hydroxyl-terminated polybutadiene (HTPB) because of its importance in the coatings and adhesives industries. 2,2-Methylene bis(4-methyl-6-tertiarybutylphenol) or A.O.2246 and 3-hydroxy pyridine have been considered as antioxidants in this study as a common HTPB antioxidant and an active antioxidant, respectively. The thermal-oxidant degradation behavior of the HTPB has been investigated in the presence of a mixture of two antioxidants by TGA and DTG tests, and, subsequently, the results of these tests have been interpreted by two model-free methods, e.g., Kissinger–Akahira–Sunose and Friedman methods. The results revealed that the mixture of two antioxidants affected the activation energy of the thermal-oxidant degradation reaction of the HTPB. The calculated activation energy value obtained from the Kissinger–Akahira–Sunose method was about 199 ± 1 kJ⋅mol−1. In addition, the Ea value at various conversion rates has also been calculated by using the Friedman method. This method showed that the highest Ea value in the thermal-oxidant degradation reaction belonged to the initiation step of the reaction (about 299 kJ⋅mol−1). Moreover, the lowest activation energy value was correlated to the second step of the degradation reaction at a conversion rate of 0.6 (about 184 kJ⋅mol−1). 相似文献
7.
Introduction3 Nitro 1,2 ,4 triazol 5 one (NTO)metalcomplexeshavemanyspecialstructuresandsomepotentialusesinammunition .1 4 Wepreviouslypreparedanddeterminedthecrystalstructureofitsmagnesiumcomplex ,5andinthispaper ,wediscusseditsthermalbehaviorbyDSCandTG/DTGtechniquesandstudieditsnon isothermalkineticsbythemeansoftheKissingermethod ,theOzawamethod ,thedifferentialmethodandtheintegralmethod .ExperimentalSample[Mg(H2 O) 6 ](NTO) 2 ·2H2 Owaspreparedasfollows :AcalculatedamountofMg(OH… 相似文献
8.
《Analytical letters》2012,45(11):1519-1525
The thermal decomposition behavior and kinetics of pyridoxine in nitrogen-only and air atmospheres were studied using thermogravimetry analysis (TGA). Kinetic interpretation of thermal analysis data for pyridoxine decomposition was carried out using Ozawa and ASTM E698 isoconversional methods. The activation energy of the decomposition process varied with the degree of decomposition and was different in the nitrogen and air atmospheres. At a 5% decomposition level, the activation energy and the pre-exponential factor were found to be 28.3 kcal mol?1 and 1.2 × 1014 min?1, respectively, in the nitrogen-only atmosphere. Thermal stability was determined by calculating the time for 5% of the pyridoxine vitamer to decompose at 25°C. The calculated shelf life for the pyridoxine vitamer obtained via TGA was surprisingly smaller in nitrogen (0.9 years) than in air (1.5 years). This is speculated to be the result of a more complex decomposition mechanism in air, involving thermo-oxidative decomposition in the presence of oxygen. 相似文献
9.
The dehydration of ferric exchanged Y zeolites is studied by thermal analysis. Their DTA shows three endotherms in the temperature range 80–450°C. The order of reaction and apparent energies of activation are calculated using various equations. The order of dehydration is nearly one and the apparent energy of activation is 4–8 kcal mole?1. The effect of heating rate is studied. The energy of activation as determined by the Kissinger and Ozawa method is about 12 kcal mole?1, which is comparable with the heat of adsorption of water determined by the gravimetric method, and is more acceptable. 相似文献
10.
The copper(II) oxalate was synthesized, characterized using FT-IR and scanning electron microscopy and its non-isothermal decomposition was studied by differential scanning calorimetric at different heating rates. The kinetics of the thermal decomposition was investigated using different isoconversional and maximum rate (peak) methods viz. Kissinger–Akahira–Sunose (KAS), Tang, Starink1.95, Starink1.92, Flynn–Wall–Ozawa (FWO) and Bosewell. The activation energy values obtained from isoconversional methods of FWO and Bosewell are 0.9 and 3.0 %, respectively, higher than that obtained from other methods. The variation of activation energy, E α with conversion function, α, established using these different methods were found to be similar. Compared to the FWO method, the KAS method offers a significant improvement in the accuracy of the E a values. All but the Bosewell maximum rate (peak) methods yielded consistent values of E α (~137 kJ mol?1); however, the complexity of the thermal decomposition reaction can be identified only through isoconversional methods. 相似文献
11.
F Xu L X Sun Z C Tan J G Liang T Zhang 《Journal of Thermal Analysis and Calorimetry》2006,83(1):187-191
Molar heat capacities
of acetaminophen were precisely measured with a small sample precision automated
adiabatic calorimeter over the temperature range from 80 to 330 K. A solid-solid
transition at 149.96 K was found from the Cp,m-T curve. The polynomial functions of Cp,.m(J
K-1 mol-1) vs. T were established
on the heat capacity measurements by means of the least square fitting method.
Thermal decomposition
processes of acetaminophen have been studied by thermogravimetry. And the
thermal decomposition kinetics parameters, such as activation energy E, pre-exponential factor A
and reaction order n, were calculated by
TG-DTG techniques with the Freeman-Carroll method, Kissinger method
and Ozawa method. Accordingly the thermal decomposition kinetics equation
of acetaminophen is expressed as: dα/dt=2.67·107e-89630/RT(1-α)0.23.
The process of fusion has been investigated through
DSC. The melting point, molar enthalpy and entropy of fusion are to be (441.89±0.04)
K, 26.49±0.44 kJ mol-1 and 59.80±1.01
J K-1 mol-1,
respectively. 相似文献
12.
Seyed Ghorban Hosseini Mohammad Ali Zarei Seyed Jafar Hosseini Toloti Hamid Kardan Mohammad Amin Alavi 《Journal of Thermal Analysis and Calorimetry》2018,131(2):925-935
In this research, ultrasound irradiation as a simple method was used to produce boron nanostructures. Reaction conditions such as boron concentration and sonication time show important roles in the size, morphology and growth process of the final products. The boron nanostructures (nanoparticles and nanorods) were characterized by scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, small-angle X-ray scattering and inductively coupled plasma atomic emission spectroscopy techniques. Primary evaluation of results showed that nanoparticles and nanorods of boron successfully have been prepared with 25–40 and 50–100 nm average particle size, respectively. These nanostructures (nanoparticles and nanorods) were studied as an additive for promoting the thermal decomposition of ammonium perchlorate (AP) particles. Thermochemical decomposition behaviors of treated samples were characterized by thermal gravimetric analysis and differential scanning calorimetry techniques. Also, the kinetic parameters of thermal decomposition processes of pure and treated samples were obtained by nonisothermal methods proposed by Kissinger and Ozawa. However, boron nanoparticles with the smallest average particle size (25–40 nm) have the most significant catalytic effect including the decrease in decomposition temperature of AP + B nanocomposite by 100 °C, increase in the heat of decomposition from 580 to 1354 J g?1 and decrease in activation energy from 207 to 110 kJ mol?1. 相似文献
13.
K. Muraleedharan 《Journal of Thermal Analysis and Calorimetry》2013,114(2):491-496
The effect of gamma ray irradiation on the rate and kinetics of thermal decomposition of potassium iodate (KIO3) has been studied by thermogravimetry (TG) under non-isothermal conditions at different heating rates (3, 5, 7, and 10 K min?1). The thermal decomposition data were analyzed using isoconversional methods of Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, and Friedman. Irradiation with gamma rays increases the rate of the decomposition and is dependent on the irradiation dose. The activation energy decreases on irradiation. The enhancement of the rate of the thermal decomposition of KIO3 upon irradiation is due to the combined effect of the production of displacements and extended lattice defects and chemical damage in KIO3. Non-isothermal model fitting method of analysis showed that the thermal decomposition of irradiated KIO3 is best described by the contracting sphere model equation, with an activation energy value of ~340 kJ mol?1. 相似文献
14.
N,N'-二(5,5-二甲基-2-磷杂-2-硫代-1,3-二噁烷-2-基)乙二胺的热分解动力学研究 总被引:3,自引:0,他引:3
以TG-DTG为手段, 研究了N,N'-二(5,5-二甲基-2-磷杂-2-硫代-1,3-二噁烷-2-基)乙二胺(DPTDEDA)在氮气气氛中的热分解动力学, 利用 Kissinger法、Flynn-Wall-Ozawa(FWO)法对DPTDEDA进行了动力学分析, 求出了该物质的热分解动力学参数, 同时利用Satava-Sestak法研究了该物质的热分解机理. 结果表明, Kissinger法所求得的表观活化能为137.37 kJ•mol-1, 指前因子ln A=28.00; Flynn-Wall-Ozawa法所求得的活化能为139.83 kJ•mol-1. DPTDEDA的热分解机理为相边界反应, 其动力学方程为G(α)=1-(1-α)4, 反应级数n=4. 相似文献
15.
The thermal decomposition of γ-irradiated KBrO3studied by dynamic thermogravimetry. The reaction order, activation energy, frequency factor and entropy of activation were computed by means of the Coats-Redfern, Freeman-Carroll and modified Horowitz-Metzger methods and were compared with those for the unirradiated salt. Irradiation enhances the decomposition and the effect increases with the irradiation dose. The activation energy is decreased on irradiation. The mechanism for the decomposition of unirradiated and irradiated KBrO3 follows the Avrami model equation, [1-(1-α)1/3] = kt, and the rate-controlling process is a phase boundary reaction assuming spherical symmetry. 相似文献
16.
Jadu Samuel Athira Surendran Sunil Culas 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):53-61
The thermal decomposition of un-irradiated and gamma-irradiated potassium bromate (KBrO3) was performed under non-isothermal conditions at different heating rates (5, 10, 15 and 20 K min?1). The data was analysed using isoconversional and non-isoconversional methods. The kinetic parameters of thermal decomposition process were obtained by three model-free isoconversional methods: Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose and Friedman. Irradiation enhances the decomposition and the effect increases with the irradiation dose. The activation energy decreases on irradiation. Kinetic analysis of data in view of various solid-state reaction models showed that the decomposition of un-irradiated and irradiated anhydrous KBrO3 is best described by the Avrami–Erofeev model equation, [?ln(l?α)]1/2 = kt. 相似文献
17.
对于非等温过程中的动力学方程,正确的Arrhenius方程的温度积分应该是从T2到T1,但是许多动力学方程中的温度积分是从T到0 K,例如Ozawa等方程。我们的研究指出对于某些反应,这些方程中的活化能存在较大的误差,因此我们提出了一个新的动力学方程。凭借等转化率法,应用新的方程可以精确求解线性或非线性加热过程中化学反应的活化能。用新方程对2个经典反应(聚酰胺的热裂解和一水草酸钙的热分解)的研究表明:Ozawa方程的活化能有时是精确的,有时偏差太大。 相似文献
18.
A series of liquid crystalline epoxides with long lateral substituent from 4 to 12 carbon atoms was synthesized and characterized by 1H NMR, FTIR spectroscopy, differential scanning calorimetry (DSC), polarized light optical microscopy (POM). The curing products of the LCE with DDM, was analyzed by POM and WAXS. The cure kinetics of epoxides and aromatic amine was investigated. The curing activation energy about 43.3-53.2 kJ mol−1 was determined and compared for all the LC epoxides through Ozawa method. The change of activation energy suggests that the reaction active depends upon the lateral substituents, because the lateral substituents parallel to the rod-like core and can act as bound solvent. 相似文献
19.
Thermal behavior of [cis-(dithiocyanato)(1,10-phenanthroline-5,6-dione)(4,4′-dicarboxy-2,2′-bipyridyl)ruthenium(II)], cis-[Ru(L1)(L2)(NCS)2] (where the ligands were L1 = 1,10-Phenanthroline-5,6-dione, L2 = 4,4′-dicarboxy-2,2′-bipyridyl) was investigated by DTA/TG/DTG
measurements under inert atmosphere in the temperature range of 298–1473 K as well as by XRD analysis of the final product.
After making detailed analysis and comparison of thermogravimetrical and MS measurements of ruthenium complex, the decomposition
mechanism of that complex was suggested. The values of activation energy and reaction order of the thermal decompositions
were calculated by Ozawa Non-isothermal Method for all decomposition stages. The calculated activation energies vary in between
32 and 49 kJ mol−1. 相似文献
20.
The thermal decomposition kinetics of nickel ferrite (NiFe2O4) precursor prepared using egg white solution route in dynamical air atmosphere was studied by means of TG with different
heating rates. The activation energy (E
α) values of one reaction process were estimated using the methods of Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS),
which were found to be consistent. The dependent activation energies on extent of conversions of the decomposition reaction
indicate “multi-step” processes. XRD, SEM and FTIR showed that the synthesized NiFe2O4 precursor after calcination at 773 K has a pure spinel phase, having particle sizes of ~54 ± 29 nm. 相似文献