TG-DTA study on the lanthanoid trifluoromethanesulfonate complexes

The thermal decomposition of the lanthanoid trifluoromethanesulfonate (triflate) complexes {Ln(CF₃SO₃)₃·9H₂O; Ln=La-Lu{ was studied by TG and DTA methods. From the endothermic and exothermic data of Ln(CF₃ SO₃)3·9H₂O complexes, pyrolysis behavior of the complexes is classified into three groups: 1) La-Nd salts, 2) Sm-Ho salts, 3) Er-Lu salts. It has also shown that all the final decomposition products were found to result in the formation of LnF₃. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal degradation of polyesters by simultaneous TG-DTA/FT-IR analysis

A combination system of thermogravimetric/differential thermal analysis (TG-DTA) and Fourier-transform infrared absorption spectroscopy (FT-IR) was described. This simultaneous TG-DTA/FT-IR technique gave spectroscopic and weight loss information about the thermal degradation process of engineering polyesters; poly(ethylene terephthalate)(PET) and poly(butylene terephthalate)(PBT). The evolved gases from PET were benzoic acid, carbon dioxide and carbon monoxide, while those from PBT were terephthalic acid esters and benzoic acid esters.

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Zusammenfassung Es wird ein kombiniertes System aus TG-DTA und FT-IR beschrieben. Mit dieser simultanen TG-DTA/FT-IR-Technik wurden spektroskopische und Massenverlustangaben über die thermische Zersetzung technisch wichtiger Polyester, namentlich von Poly(ethylenterephthalat) (PET) und Poly(Butylenterephthalat) (PBT) ermittelt. Die aus PET freigesetzten Gase waren Benzoesäure, Kohlendioxid und Kohlenmonoxid, die aus PBT freigesetzten Gase hingegen Terephthalsäureester und Benzoesäureester.

     

DTA/TG coupling

With the discovery of high temperature superconductivity an extraordinary field for investigations on new materials containing up to (more than) 8 or 9 components has been open. But, in addition to problems specifically related to superconductivity, we are faced with a prelimary difficulty: the preparation of well defined compounds which may have reproducible properties. This difficulty is smoothed out when the phase relations in the relevant systems are known. Differential Thermal Analysis (DTA) contributes to their establishment. However, in multicomponent systems, an isopletic line is expected to intercept various boundary surfaces and the analysis is obviously complicated, compared to low order systems. In addition, by the nature of high temperature superconductors the oxygen partial pressure used for their preparation is an important thermodynamic parameter which contributes to fix the oxygen content in the solid state. During heat treatments, the composition of the systems may change, due to oxygen or volatile oxides (Tl₂O₃, PbO₂ or HgO) release. A permanent composition control then requires thermogravimetric (TG) measurements associated to DTA.This paper attempts to demonstrate the efficiency of the assembly DTA/TG for the study of high temperature superconductors. Going beyond the frame of preparation and quality control, the system is also particularly useful for kinetic studies. Examples will be principally in the (Tl,Pb)-(Ba,Sr)-Ca-Cu-O systems.It is a pleasure to associate to this lecture my colleagues from research groups with which I collaborate from many years in the difficult field of elaboration and characterization of thalliumbased HTSC: T. K. Jondo, K. Lebbou. R. Abraham and M. T. Cohen-Adad in Lyon (Lab. PCM2), M. Couach and A. F. Khoder at the CEN in Grenoble (SPSMS), J. Muller and R. Flukiger at the DPMC in Geneva and of course C. Opagiste and Ph. Galez at the LSM in Annecy.     

Development and use of a TG-DTA-microscope for evaluation of pharmaceutical materials

The successful combination of microscopy with thermogravimetry-differential thermal analysis is reported. Simultaneous use of all three techniques is made possible by custom fitting a quartz glass window into the furnace of a commercially available TG-DTA. The quartz window enabled direct observations from a microscope mounted above the furnace throughout the entirety of the thermal analytical experiments. Several examples are provided for the use of this combined system for evaluating dehydrations, degradation and phase conversions in pharmaceutical materials. In some examples, microscopy provided information not accessible from the thermal analytical data alone. In others, the thermal analytical data was more informative than the microscopy.     

The use of the temperature signal and its derivative in a TG-DTA simultaneous unit

Simultaneous TG-DTA units have a work station which allows plots to be made of temperature against time, as well as the conventional TG and DTA plots. These time-temperature plots and their derivatives can be used to show details of both exothermic and endothermic events. The melting behavior of zinc is used as illustrative of endothermic phase changes. Solid-solid transitions are exemplified by noting the transitions in quartz. Examples of chemical reactions being treated to temperature-time plots are the decomposition's of zinc oxalate in nitrogen (an endothermic event) and the oxidation of carbon black in air (a sustained exothermic event). This wide selection of exothermic and endothermic events serves to illustrate the details which can be drawn from any thermogravimetric plot irrespective of the other associated equipment present, which serves to reinforce the data presented in the present study.     

煤系高岭土的DTA特征

利用程序升温热分析法得到煤系高岭土在不同气氛下的ＴＧ／ＤＴＡ谱图。通过比较煤系高岭土与普通高岭土的ＴＧ／ＤＴＡ谱图，可以发现：在惰性气氛下煤系高岭土的ＤＴＡ谱图与普通高岭土的谱图基本一致；而在空气气氛下，由于煤的燃烧反应致使煤系高岭土的吸热谷被部分或全部遮盖，另外在３００℃左右有弱的放热峰出现。比较煤系高岭土与普通高岭土的吸热谷特征可以得出煤系高岭土的结构完整性与结晶度较差。     

The application of thermal analysis and conduction calorimetry on the formation and hydration of calcium aluminoferrite

DTA was used to study the formation of calcium aluminoferrite from CaO, Al₂O₃ and Fe₂O₃ (proportion=2 x 1–x),x=0-3/4) and the effects of C4A₃ C₁₁ A₇·CacF₂, -C₂S and MgO on that process. The fusion of CF and the eutectic of CaO-Fe₂O₃, CA-C₁₂A₇, CA-C₃A, C₁₂A₇-CA-C₃A and CA-C₂A_xF_(1–x) will be favourable for the formation. The presence of -C₂S and MgO will decrease its formation temperature by an extra eutectic while C₄A₃ . and C₁₁A₇·CaF₂ will not.The early heat evolution during the hydration of C₂A_xF_(1–x) were measured by the conduction calorimeter made by ourselves and the products after 1 day hydration were examined by TG and DTA. The results revealed that the peak of heat evolution rise, the amount of the hydrating product iron hydrate gel decreases, CAH₁₀ and C₃(A, F)H₆ increase with the increase of the value x. The more MgO (up to 5%) soluted in C₆AF₂, the higher the hydration heat for this solid solution is, when TiO₂ soluted in C₆AF₂ is 2%, the hydration heat for the system reaches the highest.This project is supported by National Natural Science Fundation of China and by the National Science and Technology Developing Fundation in Building Materials Field.     

Study by thermal methods on the materials obtained by dye removal from waste waters with beech flour

The study is devoted to the characterization by both TG-DTG analysis and FTIR spectroscopy of beech flour, dyes and the sorbent-dyes products obtained through retention of the dyes from aqueous solution on the beech flour, to the aim of obtaining information on the nature of dyes’ retention, thermal behavior of the sorbent-dye materials as well as on their possible upgrading as fuel. Thermal analysis led to the conclusion that the mechanism of thermo-oxidative degradation is specific and the retention of dyes occurs on cellulose from beech flour. The nature of the bonds involved in dyes’ retention is also investigated by FTIR analysis, which evidences that dyes retention on cellulose is realized through hydrogen bonding between the NH and, respectively, OH groups from dye molecule and the oxygen atoms from cellulose. Involvement of the non-participating electrons of the nitrogen and, respectively, oxygen atoms of these groups in the extended electronic conjugation with aromatic nuclei strongly influences the capacity of the amino and, respectively, hydroxyl groups of forming hydrogen bonds, thus achieving dyes fixation on the sorbent. DTA analysis led to the conclusion that an improvement in the quality of the sorbent-dye materials as fuels is possible, as compared to untreated beach flour, as a result of the modification of the cellulosic fibers in the process of dyes retention.     

Synthesis and Thermal Study of the Barium Complexes with 8-hydroxyquinolinate Derivatives

In this present work, barium ion was reacted with different ligands which are 5,7-dibromo 5,7-dichloro, 7-iodo and 5-chloro-7-iodo-8-hydroxyquinoline, in acetone/ammonium hydroxide medium under constant stirring and the obtained compounds were as follows: (I) Ba[(C₉ H₄ ONBr₂ )₂ ]⋅1.5H₂ O; (II) Ba[(C₉ H₄ ONCl₂ )(OH)]⋅1H₂ O; (III) Ba[(C₉ H₅ ONI)₂ ]⋅1H₂ O and (IV) Ba[(C₉ H₄ ONICl)₂ ]⋅5H₂ O, respectively. The compounds were characterized by elemental analysis, infrared absorption spectrum (IR), inductively coupled plasma spectrometry (ICP), simultaneous thermogravimetry-differential thermal analysis (TG-DTA) and differential scanning calorimeter (DSC). The final residue of the thermal decomposition was characterized as orthorhombic BaBr₂from (I); the intermediate residue, as a mixture of orthorhombic BaCO₃ and BaCl₂ and cubic BaO and the final residue, as a mixture of cubic and tetragonal BaO and orthorhombic BaCl₂ (II); the intermediate residue, as orthorhombic BaCO₃ and as a final residue, a mixture of cubic and tetragonal BaO from (III); and the intermediate residue, as a mixture of orthorhombic BaCO₃ and BaCl₂ and as a final residue, a mixture of cubic and tetragonal BaO and orthorhombic BaCl₂ from (IV). This revised version was published online in July 2006 with corrections to the Cover Date.     

Study by thermal methods on some new cyclic ylides and derivatives

The study is devoted to the characterization by TG, DTG, DTA, both in air and N₂ atmosphere, of three cyclic ylides as well as two spirane derivatives, to the purpose of elucidating the correlation between structure, thermostability and thermal degradation mechanism. Thermal analysis data indicated that the degradation mechanism is characteristic for every sample, and the consequences of structural peculiarities are discussed. The thermostability series of the samples is correlated to their structure. The quantitative TG-DTG-DTA analysis allowed some considerations on the thermal degradation mechanism, subsequently confirmed by mass spectrometry. The melting points obtained by DTA and Boetius measurements along with the initial degradation temperatures from TG-DTG-DTA curves indicates the temperature range for the use and storage of these compounds, considering that some derivatives of cyclic ylides show biological activity and potential medical applications.     

Study of natural and ion exchanged vermiculite by emanation thermal analysis,TG, DTA and XRD

Emanation thermal analysis (ETA), thermogravimetry, DTA and XRD were used in thermal characterization of natural vermiculite (Santa Olalla, Huelva, Spain) and of Na^+- and - exchanged vermiculite samples during heating in air in the range 25-1100°C. A good agreement between the results of these methods was found. Changes in the radon release rate measured by ETA, which reflected the decrease and collapse of the interlayer space after the release of water as well as the formation of new crystalline phases were evaluated using a mathematical model. The model used for the evaluation was found suitable for the quantitative characterization of microstructure changes during in situ conditions of heating of vermiculite samples. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal decomposition of cadmium succinate dihydrate

Thermal decomposition of cadmium succinate dihydrate, CdC₄H₄O₄·2H₂O, was studied in dynamic helium and air atmospheres by means of simultaneous TG, DTA and MS analysis. It was found that dehydration of CdC₄H₄O₄·2H₂O takes place in the temperature range 80–165°C and at low heating rates formation of monohydrate was stated. The anhydrous cadmium succinate decomposes at about 350°C to metallic cadmium. The gaseous products of cadmium succinate decomposition are CO₂ and H₂O. Formation of small amounts of 3-phenylpropanal and 1,7-octadiene during decomposition in helium was revealed. In helium cadmium evaporates at the temperature of decomposition and the residue consists of small amount of elementary carbon formed in result of pyrolysis of succinate groups. In air cadmium oxidizes and the final solid product of decomposition is CdO.     

Effect of heating rates on TG-DTA results of aluminum nanopowders prepared by laser heating evaporation

Aluminum (Al) nanopowders with mean diameter of about 50 nm and passivated by alumina (Al₂O₃) coatings were prepared by an evaporation route: laser heating evaporation. Thermal properties of the nanopowders were investigated by simultaneous thermogravimetric-differential thermal analysis (TG-DTA) in dry oxygen environment, using a series of heating rates (5, 10, 20, 30, 50 and 90°C min⁻¹) from room temperature to 1200°C. With the heating rates rise, the onset and peak temperatures of the oxidation rise, and the conversion degree of Al to Al₂O₃ varies. However, the specific heat release keeps relatively invariant and has an average value of 18.1 kJ g⁻¹. So the specific heat release is the intrinsic characteristic of Al nanopowders, which can represent the ability of energy release.     

Characterization of some new alkali metal molybdate hydrates by thermal and X-ray methods

Preparation and characterization of four new hydrated alkali metal molybdates Na₂Mo₄O₁₃·6H₂O, K₂Mo₄O₁₃·3H₂O, Rb₂Mo₄O₁₃·2H₂O and Cs₂Mo₄O₁₃·2H₂O are described. The compounds were prepared by crystallizing the solution obtained by dissolving MoO₃ and corresponding alkali metal carbonates A₂CO₃ or molybdate A₂MoO₄ in stoichiometric amount in distilled water. The hydrated molybdates were characterized by thermal (TG/DTA) and X-ray diffraction (XRD) methods. The number of water molecules in the compounds were determined from their TG /DTA curves recorded in air and identification of their dehydration products was done by XRD. The cell parameters of the compounds were obtained by indexing their XRD patterns. Attempt to prepare the corresponding hydrated compound of lithium was not successful. This revised version was published online in July 2006 with corrections to the Cover Date.     

Crystallization of Anodic Alumina Membranes Studied by Simultaneous TG-DTA/FTIR

The thermal change of anodic alumina (AA), particularly the exothermic peak followed by the endothermic peak at ca 950°C was studied in detail by mainly using simultaneous TG-DTA/FTIR. The gradual loss of mass up to ca 910°C is attributed to dehydration. When heated at a constant rate by using TG-DTA, an exothermic peak with subsequent endothermic peak is observed at ca 950°C, but the exothermic peak becomes less distinct with decreasing heating rate. It has been found that gaseous SO₂ accompanying a small amount of CO₂ is mainly discharged at this stage. The reaction in this stage can be considered roughly in two schemes. The first scheme can be said collectively as crystallization, in which the migration of S or C trapped inside the crystal lattice of the polycrystalline phase (γ-, δ-, and θ-Al₂O₃, which presumably accompanies a large amount of amorphous or disordered phase) occurs. In the second scheme, the initial polycrystalline (+amorphous) phase crystallizes into a quasi-crystallineγ-Al₂O₃-like metastable phase after amorphization. Conclusively,after the distinct exo- and endothermic reactions, the amorphous phase crystallizes intoγ-Al₂O₃, presumably accompanying small amount of δ-Al₂O₃. It is also found that, when maintained isothermally, the metastable phases undergo transformation into the stable α-Al₂O₃ at 912°C. This revised version was published online in July 2006 with corrections to the Cover Date.     

LiNd(PO3)4晶体的热分析研究

对LiNd(PO₃)₄晶体分别在N₂气和空气下进行了TG和DTA热分析研究,给出TG和DTA曲线,讨论了LNP晶体在N₂气和空气下不同的热分解机理.得到分解产物分别为Nd₄(P₂O₇)₃和NdP₂O₇.     

Thermal differential diagnosis of mica mineral group

The following criteria can be used for differential diagnosis of mica mineral group: weight loss < 350°C; weight loss during dehydroxylation (500–1000°C); peak temperature of structural decomposition and formation of high temperature phases; course of dilatometric curves during dehydroxylation and structural decomposition interval (Fig. 1).Using the single criteria by stepwise comparing a complete thermal differentiation is possible between the members of mica mineral group.Dedicated to Dr. Robert Mackenzie on the occasion of his 75th birthday     

Efficient thermal conversion of polyyne-type conjugated polymers to nano-structured porous carbon materials

Summary Some aromatic based conjugated polymers having carbon-carbon triple bonds moiety were synthesized and carbonized. The polymers were efficiently carbonized by heating up to 900°C under an argon atmosphere, affording porous carbons in high yields. The polymer characteristics were appropriate to form nano-structured carbons in the pyrolytic carbonization process. The carbon materials were consisted of 2-4 nm sized graphitic crystallites and had slit-shaped micropores with ca. 0.7 nm pore width. Structural defects in the pre-carbon materials caused generation of mesopores with ca. 4 nm pore width after carbonization.     

热分析技术在药物研究中的应用

本文简要介绍了热分析技术在药学领域中的重要性及其应用。由于热分析技术具有试样微量化、快速简便、不用分离试样、不用溶剂、适用范围广、曲线易于解析等优点,在药学研究和药品质量检验等方面,热分析技术将发挥更重要的作用。     

Thermochemical Properties of Chemically Modified Zeolite

Zeolites chemically modified with 1, 4 or 6 M aqueous solutions of NaOH were studied by DTA, TG and ETA (emanation thermal analysis) in the temperature range 201–200°C. The structural changes in the modified zeolites at room temperature and in the modified zeolites annealed at 1000°C were studied by XRD analysis. Thermal analysis demonstrated dehydration, dehydroxylation, structural changes and a glass transition. A gradual loss in crystallinity of the chemically modified zeolites was also observed. XRD analysis revealed structural changes caused by chemical treatment and also by annealing.This revised version was published online in November 2005 with corrections to the Cover Date.