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1.
Forest fires are a plague for all countries in the world. Many factors can induce them. The organic matter (‘fuel’) in the
plant, is often responsible for the start of the fire. The bio-polymers and mainly the cellulose decompose at about 300°C
with flammable evolved gas. This decomposition is first order, and the activation energy is about 180 kJ mol−1 . On the other hand, the degradation of the lignin seems more complex, but we observed on many samples, a linearly decomposition
of the lignin vs. the heating rate (in the interval close to the start of the forest fire, 300 to 3000°C h−1 ). The decomposition of the plant during the heat is mainly dependent on the cellulose level. This degradation is also slightly
dependent on the lignin level mainly if the lignin present in this plant is less stable.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
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. 相似文献
3.
An investigation was carried out on the kinetics of thermal decomposition of plumbo-jarosite. The kinetic models of dissociation
of the compounds in the ore were identified. The results of the kinetic studies and the mechanism of the process are discussed.
The thermal decomposition of plumbo-jarosite occurs in three stages: the first up to 763, the second up to 1023 and the third
up to 1223 K, the corresponding activation energy values being 62.2, 60.3 and 98.0 kJ mol–1 , respectively.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
Thermal and Spectroscopic Studies on the Decomposition of Some Aminoguanidine Nitrates 总被引:1,自引:0,他引:1
S. R. Naidu K. V. Prabhakaran N. M. Bhide E. M. Kurian 《Journal of Thermal Analysis and Calorimetry》2000,61(3):861-871
Diaminoguanidine nitrate (DAGN) and triaminoguanidine nitrate (TAGN),potential energetic materials in emerging propulsion
technology with high mass impetus at low isochoric flame temperature have been studied as regards kinetics and mechanism of
thermal decomposition using thermogravimetry (TG), differential thermal analysis (DTA),infrared spectroscopy (IR) and hot
stage microscopy. Kinetics of thermolysis has been followed by isothermal TG and IR. For the initial stage of thermolysis
of DAGN the best linearity with a correlation coefficient of 0.9976 was obtained for the Avrami-Erofe'evequation, n=2, by isothermal TG. The activation energy was found to be 130 kJ mol–1 and logA=11.4. The initial stage of thermolysis of TAGN also obeyed the Avrami-Erofe'ev equation, n=2, with a correlation coefficient of 0.9975by isothermal TG and the kinetic parameters are E=160.0 kJ mol–1 and logA=16.0. High temperature IR spectra showed exquisite preferential loss in intensity of the NH2, NH, N–N stretching and CNN bending. Spectroscopic and other results favour deamination reaction involving the rupture of
the N–N bond as the primary step in the thermal decomposition.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
5.
The thermal decomposition reactions of calcitic dolomite were investigated. Simultaneous TG/DTG/DTA were applied under non-isothermal
conditions. From the recorded curves, the activation energies, pre-exponential factors and thermodynamic parameters of activation
were calculated for the two thermal decomposition steps.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
6.
A novel parameter of the relative rate of thermal decomposition has been defined on the basis of an analysis of equation relating
the logarithm of the conversion degree on the temperature. The dependence of this parameter on temperature in the dynamic
conditions has been analyzed and discussed. The dependence of the relative rate of thermal decomposition is a linear relationship
involving two coefficients. These coefficients can be related to the enthalpy and activation energy. The parameter developed
has been used for the analysis of a series of consecutive reactions of thermal decomposition of calcium oxalate monohydrate.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
7.
A series of compounds obtained from urea, phosphoric acid and inorganic salts of Zn, Ni and Ca, were tested in respect of their flame‐retardancy behavior. The estimation criteria were the kinetic parameters obtained in air, under non‐isothermal conditions, on a Perkin‐Elmer Diamond device, at heating rates of 5, 10, 12 and 15 deg·min?1. The flame‐retardancy effect was assigned to the significant endothermic decomposition at relatively low temperature (150–200°C). The quantitative estimation of the thermal behavior was performed by comparison of the kinetic data obtained by Flyn‐Wall‐Ozawa, Friedman and NPK (Sempere‐Nomen) methods. The kinetic homogeneity and a very good quality of the model are arguments in favour of the NPK method. The Ni containing material exhibited the best flame‐retardancy behavior, i.e. higher activation energy and mass loss, respectively a single decomposition step with both physical and chemical processes. The results were validated by fire resistance tests. 相似文献
8.
Pinheiro G. F. M. Lourenço V. L. Iha K. 《Journal of Thermal Analysis and Calorimetry》2002,67(2):445-452
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. 相似文献
9.
Differential scanning calorimetry (DSC) was used to determine the molar enthalpies of dehydration and decomposition of CoC2O4·2H2O, Co(HCOO)2·2H2O and [Co(NH3)6]2(C2O4)3·4H2O. The first stage of dissociation of each compound is a single-step dehydration both in air and argon atmospheres. The next
stages are decomposition processes influenced by experimental parameters. The enthalpies of dehydration and decomposition
vary from compound to compound in each atmosphere. The obtained data have been related to the macromechanisms proposed for
the thermal decomposition and the parallel-consecutive decomposition-oxidation processes.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
铝粉粒度对高氯酸铵热分解动力学的影响 总被引:2,自引:0,他引:2
采用热重-差示扫描量热(TG-DSC)联合技术研究了10.7 μm, 2.6 μm和40 nm铝粉对高氯酸铵(AP)热分解的影响. 结果表明, 铝粉的加入对AP的低温放热峰有抑制作用, 对高温放热分解反应有促进作用, 并且随铝含量的增加和铝粒径的减小这种作用更强烈. 采用多元非线性拟合技术对不同升温速率下TG-DSC实验数据进行拟合, 结果表明, 质量分数为40%的不同粒径铝粉的加入对AP的热分解三阶段(A→B→C→D)反应模型无影响, 但反应机理函数发生了改变. 纯AP, AP/Al(10.7 μm), AP/Al(2.6 μm)及AP/Al(40 nm)的反应机理函数组合分别为C1/D1/D1, C1/D1/D3, C1/D1/D4和C1/D1/F2. 相似文献
11.
The authors present data concerning the evaluation of kinetic parameters of the decomposition of a Mannich compound by using
the classical method of constant heating rate thermal analysis and the new one of controlled rate thermal analysis (CRTA).
The data processed using the CRTA method allow to obtain more reliable kinetic parameters according to the proposed reaction
mechanism.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
12.
Polystyrene/iron-nickel (PS/FeNi3) nanocomposites were synthesized via an in-situ polymerization route and characterized by XRD,SEM and FTIR. FeNi3 nanoparticles were characterized by TEM and XRD. The pure FeNi3 nanoparticles (100~125 nm) were highly clustered and percolated through the PS matrix. When the content of FeNi3 nanoparticles reached 5 wt%,an interaction between FeNi3 nanoparticles and PS matrix was observed. The thermal decomposition behavior of PS/FeNi3 nanocomposites was investigated by thermal analysis. The activation energies (E) and pre-exponential factors (lnA) were calculated by using Archar method. The results show that the thermal decomposition of pure PS is a one-dimensional diffusion mechanism. A three-dimensional diffusion mechanism appears when FeNi3 nanoparticles incorporate. The E of PS/FeNi3 nanocomposites with different FeNi3 contents is 217.5,225.3,180.6 and 73.0 kJ·mol-1,and the corresponding lnA is 35.6,34.9,27.5 and 10.4 S-1,respectively. 相似文献
13.
通过热重分析研究了新型三元共聚物聚碳酸亚丙酯马来酸酐(PPCMA)在不同升温速率下的热分解动力学.设计并引入一种新的计算方法,非线性约化法(NLA),对共聚物热分解过程中的表观活化能进行了计算.研究发现,虽然用非线性约化法计算的表观活化能相对误差值稍大于用传统计算方法Flynn-Wall-Ozawa(FWO),Tang和Kissinger-Akahira-Sunose(KAS)计算的相对误差值,但其分析合理且计算过程更为简便.此外,固态反应模型拟合方法计算结果表明,共聚物的热分解过程对应多个反应机理.整个热分解过程,表观活化能值处于70-135kJ·mol-1之间,指前因子处于5.24×104-9.89×107min-1之间.同时,通过对表观活化能值的比较,初步解释了聚碳酸亚丙酯(PPC)与PPCMA热解温度差异的原因. 相似文献
14.
15.
A. N. Pavlov 《Russian Chemical Bulletin》1997,46(11):1848-1850
Thermal decomposition of dinitramide onium salts proceedsvia the dissociative mechanism when pK
a of the base is lower than 5.0 andvia the monomolecular decay of the anion at pK
a>7.0. On going from the melt to the solid state, the reaction mechanism does not change, and the rate decreases by 1–2 orders
of magnitude. No anomalous effects inherent in dinitramide metal salts in the solid phase are observed during decomposition
of onium salts.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1951–1953, November, 1997 相似文献
16.
B. Zhou S. Jiang L. Zou X. Wang D. Wang J. Liu S. Shang D. Zhou 《Journal of Thermal Analysis and Calorimetry》1999,58(2):487-493
A new compound cyclohexyl-t-butyldimethylammonium tetraphenylborate, [C6H11N(CH3)2(C(CH3)3)]BPh4 has been prepared, and its decomposition mechanism was studied by TG. The IR spectra of the products of thermal decomposition were examined at every stage. Kinetic analysis for the first stage of thermal decomposition process was obtained by TG and DTG curves, and kinetic parameters were obtained from the analysis of the TG-DTG curves with integral and differential equations. The most probable kinetic function was suggested by comparison of kinetic parameters.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
17.
18.
Introduction Dinitroglycoluril (DINGU) is a typical cyclourea nitramine. Its crystal density is 1.94 gcm-3. The detonation velocity corresponding to =1.94 gcm-3 is about 8450 ms-1. Its sensitivity to impact is better than that of cyclotrimethylenetrinitramine. It has the potential for possible use as high explosive from the point of view of the above-mentioned high performance. Its preparation,1-4 properties1-4 and hydrolytic behavior4 have been reported. In the present paper, we report i… 相似文献
19.
N. Ózpozan H. Arslan T. Ózpozan M. Merdivan N. Külcü 《Journal of Thermal Analysis and Calorimetry》2000,61(3):955-965
Thermogravimetry (TG) and differential thermal analysis (DTA) were performed on the complexes with general formula (M(DEBT)n (where M =Fe, Co, Ni, Cu or Ru; n =2, or 3 and DEBT=N,N-diethyl-N'-benzoylthiourea). Derivative thermogravimetric (DTG) curves were also recorded in order
to obtain decomposition data on the complexes. The complexes of Fe(III), Co(II), Ni(II), Cu(II) and Ru(III) displayed two-
or three-stage decomposition patterns when heated in a dynamic nitrogen atmosphere. Mass loss considerations relating to the
decomposition stages indicated the conversion of the complexes to the sulfides or to the corresponding metal alone (Cu, Ru,
NiS, CoS or FeS). Mathematical analysis of the TG and DTG data showed that the order of reaction varied between 0.395 and
0.973. Kinetic parameters such as the decomposition energy, the entropy of activation and the pre-exponential factor are reported.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
20.
利用热重分析仪(TGA)对预氧化聚铝碳硅烷(PACS)纤维进行了热动力学研究, 用改良的Coats-Redfern法计算了动力学参数, 用Doyle法计算了理论失重值, 并根据FT-IR, XRD和SEM对其热分解的机理进行了分析. 结果表明, 在热分解反应的主要阶段, 预氧化纤维的反应活化能低于PACS纤维, 氧的引入有利于纤维的热分解; 快速升温有利于预氧化PACS纤维的热分解. 在初始分解阶段, 主要为低分子量的PACS和H2O的逸出, 同时≡Si—H键之间以及≡Si—H与≡Si—CH3键发生了脱氢、脱CH4反应, 从而导致交联程度的增加; 随热分解温度进一步的提高, 分子的有机侧基急剧热解, 分解产物从有机物转变为存在部分微晶的无机结构; 热分解温度继续提高, 纤维结构进一步完善, 1300 ℃左右, β-SiC晶粒大小约为2~4 nm左右, 纤维具有较好的性能. 相似文献