共查询到18条相似文献,搜索用时 62 毫秒
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ZnAc2·2H2O在空气中的热分解动力学研究 总被引:2,自引:0,他引:2
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. 相似文献
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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
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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
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硫酸铝钾热分解反应动力学模型 总被引:13,自引:0,他引:13
近年来,在热分析动力学研究领域内,已有许多动力学模式及相应数据处理方法来描述固相反应的最可能机理,如:aRCHAR微分法[1]Coats-Redfe积分法[2]相结合的方法和等温过程与非等过程相结合的方法[3]等。而最近Dollimore等人[4]提出了利用 TA曲线的特征来确定动力学模型的方法,从而避免了对 f(a)和 g(a)逐一尝试的麻烦。本文就是用该法来研究硫酸铝钾的热分解动力学。硫酸铝钾热分解过程虽然已有人研究[5],但其动力学则未见文献报道。1 实验部分 实验工作在美国PE公司TGA7热分析仪上完成,反应气氛为氮气,流速为40mL·min-1 ,… 相似文献
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KNCO通常用氢氧化钾和尿素在熔融态下反应而合成,其中过量的尿素用长时间高温焙烧来除去。我们用热重法对KNCO粗品中的尿素进行了热分解动力学研究,以期确定合理的焙烧温度和时间。将分析纯尿素和氢氧化钾按1.7:1(摩尔比)混合均匀,加热熔融,搅拌反应2小时,得含有剩余尿素的白色KNCO试样。热解用北京光学仪器厂LCT型差热天平,a-Al_zO_3为参比物,空气气氛,升温速率10℃/min。红外光谱用Nicolet 5DX型仪,KBr压片。 结果与讨论 相似文献
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Zr(OH)4的热分解及ZrO2的相变过程 总被引:1,自引:0,他引:1
利用TG-TDG-DTA热分析技术研究了由Zr(OH)4热分解制备ZrO2的脱水过程,并结合X射线粉末衍射技术研究了ZrO2的相变过程.发现在82℃的吸热峰对应Zr(OH)4的脱水,而435℃附近出现的放热峰则为四方ZrO2向单斜ZrO2的晶相转变.采用外推法确定了Zr(OH)4脱水过程遵循三维扩散机理,其函数方程为g(α)=[{1/(1-α)}^1/3-1]^2.以实验获得的动力学参数ln A和E为基础,用最小二乘法对ln A和E进行线性拟合,得到动力学补偿效应表达式为ln A=0.437E-20.69. 相似文献
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The thermal decomposition of some Ni(II)-carboxylate-imidazole complexes in a nitrogen atmosphere was studied non-isothermally.
From the non-isothermal thermoanalytical data, it was found that these complexes decompose through a stepwise release of imidazole
molecules and/or CO ones forming unstable intermediates which produce metal oxide or the metal as a final decomposition product.
TG in conjunction with DTG were used to evaluate the kinetic and thermodynamic parameters of the decomposition reaction. The
kinetic studies were performed employing a computer-oriented kinetic analysis of each set of W-T data obtained under constant heating rate. The diffusion processes are the decisive mechanisms for the decomposition. The
values of ΔE, A, ΔH, ΔS and ΔG for activation were calculated for the complexes and correlated to variation in their structure.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Miranda P. Matos J. R. Mercuri L. P. Araújo M. P. B. M. Vicentini G. Zinner L. B. 《Journal of Thermal Analysis and Calorimetry》2002,67(2):465-472
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. 相似文献
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A. Y Obaid A. O. Alyoubi A. A. Samarkandy S. A. Al-Thabaiti S. S. Al-Juaid A. A. El-Bellihi El-H. M. Deifallah 《Journal of Thermal Analysis and Calorimetry》2000,61(3):985-994
The thermal decomposition of copper(II) acetate monohydrate was studied in air and nitrogen atmospheres by means of DTA-TG
and SEM measurements. The kinetics of the thermal decomposition steps in air was studied by using isothermal and non-isothermal
thermogravimetric techniques. The results are discussed in terms of various reaction interface models and different techniques
of computational analysis of non-isothermal data. The activation parameters, calculated by using a composite method of integral
analysis of non-isothermal data, revealed not only their independence from the heating rate and fractional reaction, but also
a better correlation and agreement with the results obtained under isothermal conditions.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Thermal behaviour of intercalated 8-hydroxyquinoline (oxine) in montmorillonite clay 总被引:1,自引:0,他引:1
I. A Pastre I. do Nascimento Oliveira A. B. S Moitinho G. R. de Souza E. Y. Ionashiro F. L. Fertonani 《Journal of Thermal Analysis and Calorimetry》2004,75(2):661-669
The composite montmorillonite-8-hydroxyquinoline (Swy-1-8-HQ) was prepared by two different processes and studied by using
thermogravimetric analysis (TG/DTG and DSC), as well as helpful techniques as fluorescence in the UV-visible region and X-ray
diffraction. The composites developed fluorescent appearance, however with quantum poor efficiency and they exhibited distinct
TG and DSC thermal behavior. The fluorescence data of spectra associated to the TG/DT curves allowed to suggest that the 8-HQ
was present in the composites in two different circumstances: 1 - intercalated in the interlayer spaces (Swy-1-8-HQ2), rigidly
associated to the substrate feasible as a monolayer with the aromatic rings parallel to the silica layer; and/or, 2 - adsorbed
on the surface (Swy-1-8-HQ1), either as a bilayer formation or tilting of the molecules to the silicate layer sheet. All results
confirmed above are in agreement with X-ray diffraction patterns, once the interlayer space increases when 8-HQ is incorporated.
The experimental results confirm the formation of the composites in agreement with the method used in the preparation.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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环戊烷和环己烷在silicalite-1分子筛上的热脱附行为 总被引:1,自引:0,他引:1
采用智能质量分析仪(IGA)及TG/DTG法研究了环戊烷和环己烷在硅沸石silicalite-1上的热脱附行为。当环戊烷在silicalite-1上吸附量小于4 m/uc时,TG/DTG曲线表明环戊烷在silicalite-1上存在一个脱附过程。吸附量大于4 m/uc,TG曲线显示热脱附过程明显分为两个阶段,DTG曲线中出现两个明显的脱附峰,彼此分离。环己烷在silicalite-1上只存在一种脱附过程,DTG曲线只出现一个脱附峰。从环戊烷和环己烷的热脱附曲线中也可看出,随着吸附量的增加脱附峰温逐渐向高温方向偏移。 相似文献
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I. M. M. Kenawy M. A. H. Hafez R. R. Lashein 《Journal of Thermal Analysis and Calorimetry》2001,65(3):723-736
The complexes formed by the chemically modified chloromethylated poly(styrene)-PAN (CMPS-PAN) as a resin chelating ion exchanger
were characterized by infrared and potentiometry. The thermal degradation of pure CMPS-PAN resin and its complexes with Au3+, Cr3+, Cu2+, Fe3+, Mn2+ and Pt4+ in air atmosphere has been studied using thermal gravimetry (TG) and derivative thermal gravimetry (DTG). The results showed
that four different steps accompany the decomposition of CMPS-PAN resin and its complexes with the metal ions. These stages
were affected by the presence of the investigated metal ions. The thermal degradation of CMPS-PAN resin in the presence of
the ions showed different stability of the resin in the following decreasing order: Au3+>Pt4+>Mn2+>Cu2+>Cr3+>Fe3+. On the basis of the applicability of a non-isothermal kinetic equation, the decomposition process was a first-order reaction.
The activation energy, Ea, the entropy change, ΔS
*, the enthalpy change, ΔH
* and the Gibbs free energy of activation, ΔG
* were calculated by applying the theory of the reaction rates. The effect of the different central metal ions on the calculated
thermodynamic activation parameters was discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献