Feasibility Study of Crude Oil Fields by Thermal Analysis Techniques

This paper investigates the minimum oil content necessary for self-sustained combustion, which is introduced as a criterion for the selection of suitable reservoirs for in-situ combustion processes. Differential scanning calorimetry was used to determine the heat values of oil-limestone mixtures. The minimum temperature required for the total consumption of the fuel was obtained by thermogravimetry (TG/DTG). The minimum amount of oil necessary to sustain combustion was calculated from these two parameters and compared with the oil content of the reservoir. Reservoirs with an oil content greater than or equal to this minimum value were considered feasible. It was seen that the fields examined are generally not suitable for in-situ combustion processes. This revised version was published online in August 2006 with corrections to the Cover Date.     

Thermal Decomposition of Hydrated Lanthanide Picrates by TG/DTG and DSC Analyses

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.     

ZnAc2·2H2O在空气中的热分解动力学研究

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.     

The Influence of Silica to Alumina Ratio on Y Zeolite Activity by Simultaneous TG and DSC Analysis

Simultaneous TG and DSC analyses of n-butylamine adsorption/desorption were carried out over several zeolites with different degrees of dealumination. The samples used consisted of high crystalline zeolites, preparedvia steam/leaching sequential treatments, and characterized by various techniques. Catalyticactivity measured as the initial rate of cracking of 1,3,5-triisopropylbenzene did not correlate with total acidity, however, the energy required to the complete desorption of the probe molecule, determined by integration of DSC curves, correlates with the catalytic activity of zeolites with any or little extra-framework alumina content. High amounts of extra-framework alumina give significant constraint effect to acessibility to acid sites as shown by applying the Crank's method to the TG curves. This method allowed to determine the intra-crystalline diffusivity of the probe molecule, which seems to be the controlling step to the cracking reaction. This revised version was published online in July 2006 with corrections to the Cover Date.     

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。     

Thermal decomposition and indirect structural determination of rare earth element picrates with the dtso ligand

The complexes [Ln(pic)₃(DTSO)₃] (Ln=La, Lu and Y; pic=picrate; DTSO=1,3-dithiane-1-oxide) were synthesized and characterized. Indirect structural determination by far infrared spectroscopy is presented. Results from thermal decomposition of these complexes by TG/DTG and DSC techniques are reported. This revised version was published online in August 2006 with corrections to the Cover Date.     

Thermal analysis study of the effect of coal-burning additives on the combustion of coals

Thermal analysis is widely used in combustion research for both fundamental and practical investigations. Efficient combustion of coals in cement industry is very important and necessary. In this research, the effects of three coal-burning additives on burning behaviour of bituminous coal and anthracite were studied with the help of thermogravimetry (TG) and differential scanning calorimetric (DSC) analysis. The kinetic study was carried out and the results were presented. The results showed that the coal-burning additives especially LSZ can reduce the ignition temperature, increase the ignition index D _i, combustion ending index D _f and affect the activation energy of the coal samples studied. The coal-burning additives especially LSZ can improve coal combustion effectiveness.     

Thermal behaviour of intercalated 8-hydroxyquinoline (oxine) in montmorillonite clay

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.     

Thermal Analysis of Polymer-silicate Nanocomposites

The thermal behavior of epoxy-smectite nanocomposites (hybrids) is examined by non-isothermal thermogravimetry (TG, DTG and DTA) in air atmosphere. It has been shown that the thermal stability of hybrids is much greater than that of epoxy resin and strongly depends on both the smectite loading and the type of the gallery cations of organically modified smectites. The kinetics of degradation of nanocomposites is significantly influenced by the presence of smectites and proceeds in three stages. Stage I is attributed to the effect of quaternized ammonium ion exchanged smectite, as stages II and III are associated with the decomposition of the bulk epoxy resin. Because of the interfacial interactions and thesilicate-polymer multilayered nanoscale organization, the nanocomposites act as excellent heat insulator and mass transport barrier, which shift the thermal decomposition peaks towards much higher temperatures. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal Behaviour of Some Terpenoids

The terpenoids acetyl sitosterol, lupeol, acetyl diosgenin and stigmasterol were studied. Comparison of the thermogravimetric curves and the activation energies of the terpenoids suggested the following sequence of thermal stability: acetyl sitosterol < acetyl diosgenin < lupeol < stigmasterol. The DSC curves allowed determination of the melting points and the degrees of purity. Comparison of the TG and DSC curves revealed the presence of phase transitions without mass loss that were attributed to rearrangements in the terpenoid molecules. This revised version was published online in August 2006 with corrections to the Cover Date.     

Morphological and Thermal Properties of Vesicular Phospholipid Gels Studied by DSC,Rheometry and Electron Microscopy

Semisolid phospholipid preparations have been well known for several years and are still investigated as drug carrier systems, e.g. for potential cancer therapy. They may be applied parenterally as semisolid vesicular phospholipid gels suitable as implants for sustained drug release or as liposomal preparations after redisperging the stable storage form. Due to enhanced stability, mixtures of hydrated phospholipids and cholesterol are more suitable than natural unsaturated phospholipids. In order to describe characteristics of vesicular phospholipid gels, only a few techniques may be useful. Especially the structure of the semisolid preparation is not yet completely understood. We tried to get some more information about these systems by using a combination of freeze-fracture electron microscopy, differential scanning calorimetry and rheometry to elucidate, on the one hand, the inner structure or homogeneity and, on the other, the thermotropic phase transition of the three-dimensional lipid network and the temperature dependency of the fluidity/viscosity of the samples. Using freeze-fracture electron microscopy we found coexisting phospholipid domains of lamellar sheets and vesicular structures. With the help of differential scanning calorimetry the reasons for the different phase behaviour were elucidated. Rheometric measurements show increased intermediate viscosity at the thermotropic phase transition of the lipid bilayers, possibly induced by interacting membrane defects. This revised version was published online in August 2006 with corrections to the Cover Date.     

Thermal Analysis of the High-Energetic Material HNF

In a search for new storable high performance propellants for the European Space Agency (ESA), the solid oxidiser hydrazinium nitroformate (HNF) has been identified as a very promising ingredient for a new storable composite propellant. The purity and stability of HNF after production are very important indicators for the quality of HNF. In order to characterise HNF,many thermal analysis techniques as DSC and TG/DTA were performed to obtain more information about its stability and its (in)compatibility with other materials. Also some less familiar techniques such as the vacuum stability test and microcalorimetry have been performed. In relation to the safety, a relation between the friction and impact sensitivity and the physical-chemical properties is made. This revised version was published online in July 2006 with corrections to the Cover Date.     

Utilization of Thermal Analysis to Establish the Optimal Conditions for Regeneration of Activated Carbons

Thermoanalytical methods (TG, DTG and DTA) were used to determine the temperature interval (140–350°C) in which p-nitroaniline undergoes thermal desorption from the surface of activated carbons obtained from the shells of oxidized plum stones and impregnated with aqueous solutions of Cu, Fe and Ti salts, which simulate the processes of activated carbon regeneration. It was established that the impregnation of the activated carbons facilitated the regeneration processes in the sense that they can occur at lower temperatures: 135–320 (Cu), 150–340 (Ti) and 130–320°C (Fe). The utilized activated carbons were preliminarily characterized by BET surface area, DSC and scanning electron microscopic methods. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal behavior of polystyrene synthesized in the presence of carboxymethyl cellulose

Summary Study of the decomposition kinetics is an important tool for the development of polymer recycling in industrial scale. In this work, parameters such as activation energy, frequency factor and reaction order, were measured under dynamic conditions. Flynn-Wall-Ozawa, Van Krevelen, Horowitz-Metzger, Coats-Redfern, Madhusudanan and Vyazovkin methods were used to determine the kinetic parameters. The analysis of the results obtained by the Coats-Redfern method shows that the thermal degradation process of LDPE and HDPE corresponds to a phase boundary controlled reaction (mechanism R2). This method shows that the reaction order values of LDPE and HDPE are about 0.7 and 0.6, respectively.     

鲍鱼多糖Hal-A的热分析研究

采用热重、热重-红外谱联用及差示扫描量热法，对鲍鱼多糖进行热分析研究 ，结果表明鲍鱼多糖在空气和氮气氛中，230 ～ 340 ℃之间发生剧烈的分解反应 。氮气氛中，是吸热的分解过程；而空气氛中，是放热氧化反应，并且在453 ℃左 右，有另一个急剧的氧化裂解过程。与淀粉、肝素、甲壳素和半乳糖的热分析比较 ，含有硫酸酯的鲍鱼多糖和肝素热稳定性较低，含氨基的甲壳素最高，这反映出不 同基团对多糖热稳定性的影响。     

Measurements of Heat of Zeolite Dehydration by Scanning Heating

A procedure for measurement of the heat of zeolite dehydration by scanning heating has been designed. Simultaneous data on heat flow (DSC) and mass loss (TG) are required for evaluation. The heating rate depends on the experimental conditions (point-spread function, sample mass, crucible design, and calorimetric reproducibility). Dehydration measurements have three advantages as compared with the sorption procedure: i) one can investigate samples with irreversible dehydration; ii) no approximation model is needed for calculation of the partial molar heat of dehydration; and iii) the procedure is not labor-consuming.The procedure was tested on the natural zeolites heulandite, chabazite and mordenite. The results are close to those measured by the sorption procedure. The partial molar heat of dehydration was found to depend on the water content. It increases from 50 to 87 J mol^–1 K^–1 for heulandite, from 53 to 81 J mol^–1 K^–1 for chabazite, and from 51 to 71 J mol^–1 K^–1 for mordenite.The approximation of the heat of sorption by linear regression was found to be wrong. Detection of a phase transitioN after this approximation has no meaning.This revised version was published online in November 2005 with corrections to the Cover Date.     

Thermal Decomposition and Melting of A New Carboxyindole Derivative

GV150526A is a novel 2-carboxyindole derivative, recently synthesized by GlaxoWellcome, which is used in treatment or prevention of CNS disorders resulting from neurotoxic damage. It has been prepared in three forms, F1, F2 and F3, having significantly different hydration/dehydration behavior and/or diffraction patterns. Here, we extend the thermal analysis of these polymorphs above 200°C, where all forms are fully dehydrated and the main thermal phenomena are decomposition and melting. Simultaneous TG/DSC measurements have been repeated in wet and dry nitrogen atmospheres over a wide range of heating rates. Form F3 displays a qualitatively different behavior relative to F1 and F2. This fact is interpreted as an evidence of a mechanism of decomposition which sets F3 apart from F1 andF2. The thermal data are summarized by simple heuristic equations and few ‘apparent’enthalpies. This revised version was published online in August 2006 with corrections to the Cover Date.     

Thermal properties of biocomposites

Thermal properties of new biocomposites prepared from modified starch matrix reinforced with natural vegetable fibres were studied. DSC and TG methods were applied to study thermal behaviour of biocomposites. Biocomposites were obtained in the laboratory twin-screw extruder. Two kinds of natural fibres were used, i.e. flax and cellulose in the amount of 0–40 mass%. DSC curves of biocomposites reveal glass transition temperature, attributed to the amorphous nature of the plasticized starch matrix. In general, incorporating natural fibres into modified starch matrix leads to an increase in glass transition temperature. Thermal degradation of modified starch matrix and cellulose reinforced biocomposites proceeds in three steps, whereas the degradation process of flax reinforced biocomposites occurs in two steps. For unreinforced matrix as well as for all biocomposites, regardless of type and amount of reinforcement, the major mass loss is observed at the temperature above 300°C. The increase in thermal stability with introduction of natural fibre is observed for both flax and cellulose reinforced biocomposites.     

Thermal properties,induction period,interfacial energy and nucleation parameters of solution grown benzophenone

The kinetic parameters (reaction order, n, activation energy, E, pre-exponential factor, A, constant rate, k) for the dehydration step due to elimination of osmotic water and hydrogen-bounded water with the carboxylic groups, and for the anhydrifying step owing to the dehydration of two neighboring (-COOH) groups, were determined under non-isothermal conditions for some carboxylic resins with acrylic-divinylbenzene (DVB) matrix. The kinetic parameters were evaluated by means of isoconversional methods from (TG/DTG) thermal analysis data. The results show a dependence of the apparent kinetic parameters on the cross-linking degree, granulation, gel/macroporous matrix nature, exchange capacity and heating rate.