摘要 :
The thermal decomposition of lanthanide complexes, with a general formula: [LnL(NO3)2](NO3), where Ln = La, Pr, Nd, Sm, Gd, Tb, Dy, and Er; and L = bis-(salicyladehyde)-1,3-propylenediimine Schiff base ligand, was studied by therm...
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The thermal decomposition of lanthanide complexes, with a general formula: [LnL(NO3)2](NO3), where Ln = La, Pr, Nd, Sm, Gd, Tb, Dy, and Er; and L = bis-(salicyladehyde)-1,3-propylenediimine Schiff base ligand, was studied by thermogravimetric (TG) and derivative thermogravimetric (DTG) techniques. The TG and DTG data indicated that all complexes are thermostable up to 398 K. The thermal decomposition of all Ln(III) complexes was a two-stage process and the final residues were Ln _2O_3 (Ln = La, Nd, Sm, Gd, Dy, Er), Tb_4O _7, and Pr_6 O_(11). The activation energies of thermal decomposition of the complexes were calculated from analysis of the TG-DTG curves using the Kissinger, Friedman, and Flynn-Well-Ozawa methods.
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In a recent publication, Chen et al. (2011) [ 1 ] studied the thermogravimetric behavior of the combustion of the microalgae Chlorella vulgaris and described a kinetic analysis based on Kissinger-Akahira-Sunose (KAS) and Flynn-Wal...
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In a recent publication, Chen et al. (2011) [ 1 ] studied the thermogravimetric behavior of the combustion of the microalgae Chlorella vulgaris and described a kinetic analysis based on Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods in the work entitled: "Thermogravimetric analysis of microalgae combustion under different oxygen supply concentrations" (Appl. Energy 88 (2011)3189-3196). Some comments about this work are discussed in the present letter to the editor.
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Thermal analysis and differential thermal analysis offers a novel means of studying the desorption of acids such as stearic acid from clay surfaces. Both adsorption and chemisorption can be distinguished through the differences in...
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Thermal analysis and differential thermal analysis offers a novel means of studying the desorption of acids such as stearic acid from clay surfaces. Both adsorption and chemisorption can be distinguished through the differences in the temperature of mass losses. Increased adsorption is achievable by adsorbing onto a surfactant adsorbed montmorillonite. Stearic acid sublimes at 179 A degrees C but when adsorbed upon montmorillonite sublimes at 207 and 248 A degrees C. These mass loss steps are ascribed to the desorption of the stearic acid on the external surfaces of the organoclays and from the de-chemisorption from the surfactant held in the interlayer of the montmorillonite.
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The surface functionalization of silica by alkoxysilane can improve its dispersion into polymers by beneficially modifying interparticle and particle–polymer interactions. Thermogravimetric analysis (TGA) has been used to study t...
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The surface functionalization of silica by alkoxysilane can improve its dispersion into polymers by beneficially modifying interparticle and particle–polymer interactions. Thermogravimetric analysis (TGA) has been used to study the kinetics of binding a bifunctional alkoxysilane onto silica over the temperature range of 50 to 110 °C. DerivativeTGAcurves of the reacted silica show distinct peaks, which correspond to the alkoxysilane bound to one or two surface silanol sites. Binding at two silanol sites is postulated to occur in a two-step series reaction model. An Arrhenius analysis for the alkoxysilane binding reactions shows that the activation energies of the two reaction steps are similar, which is expected because the alkoxysilane contains two identical binding groups. This work demonstrates the suitability of theTGAtechnique to investigate the reaction kinetics for modifying the surface of silica.
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This research comprises the determination of kinetic parameters of in situ combustion processes by reaction tube and thermal (thermogravimetric analysis (TGA)/differential thermogravimetric analysis (DTGA)) experiments. A previous...
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This research comprises the determination of kinetic parameters of in situ combustion processes by reaction tube and thermal (thermogravimetric analysis (TGA)/differential thermogravimetric analysis (DTGA)) experiments. A previously developed laboratory model and a Du Pont 9900 thermalanalyzer unit were used to run the experiments. Three reaction regions for combustion of crude oil in porous media were observed in the reaction tube and TGA/DTGA experiments and are defined as low temperature oxidation, fuel deposition and high temperature oxidation. The kinetic parameters are calculated for each reaction region using Weijdema's reaction model in reaction tube experiments. The Arrhenius model is applied to determine the kinetic parameters from TGA/DTGA thermograms and a comparison is made between kinetic results.
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The desorption of benzoic acid and stearic acid from sodium and calcium montmorillonites has been studied using thermogravimetric and differential thermogravimetric analysis. Desorption of benzoic acid from sodium montmorillonites...
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The desorption of benzoic acid and stearic acid from sodium and calcium montmorillonites has been studied using thermogravimetric and differential thermogravimetric analysis. Desorption of benzoic acid from sodium montmorillonites occurs at 140 degrees C and from calcium montmorillonites at 179 degrees C. This increase in temperature is attributed to the benzoic acid bonding to the calcium in the interlayer. A lowering of the dehydroxylation temperature of montmorillonites is observed with acid adsorption. Stearic acid desorbs at 218 degrees C as observed by the DTG curves. The desorption pattern differs between the sodium montmorillonites and the calcium montmorillonites.
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摘要 :
The desorption of benzoic acid and stearic acid from sodium and calcium montmorillonites has been studied using thermogravimetric and differential thermogravimetric analysis. Desorption of benzoic acid from sodium montmorillonites...
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The desorption of benzoic acid and stearic acid from sodium and calcium montmorillonites has been studied using thermogravimetric and differential thermogravimetric analysis. Desorption of benzoic acid from sodium montmorillonites occurs at 140 degrees C and from calcium montmorillonites at 179 degrees C. This increase in temperature is attributed to the benzoic acid bonding to the calcium in the interlayer. A lowering of the dehydroxylation temperature of montmorillonites is observed with acid adsorption. Stearic acid desorbs at 218 degrees C as observed by the DTG curves. The desorption pattern differs between the sodium montmorillonites and the calcium montmorillonites.
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Integral parts of any automotive fluid system are the seals. Elastomers are used in automotive applications for their resilience and rebound attributes. These elastomeric parts are flexible, impervious to hostile engine environmen...
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Integral parts of any automotive fluid system are the seals. Elastomers are used in automotive applications for their resilience and rebound attributes. These elastomeric parts are flexible, impervious to hostile engine environments, including hot-stressed additized motor oils. There are a number of standard tests for tensile quality and elongation of rubber seals and parts. Most standard rubber tests are based on quasi-real world conditions. Thermal analysis can be used to evaluate rubber seals and parts for composition by thermogravimetric analysis (TGA). Dynamic mechanical analysis (DMA), thermomechanical analysis (TMA) and differential scanning calorimetry (DSC) can ascertain mechanical strength and the glass transition temperature. T-g. TGA/differential thermal (DTA), DSC and pressure DSC can evaluate the oxidative stability of seals. Results of a TMA and TGA quality control test differentiated pass and fail elastomeric seals and parts. Characterization of several failed seals revealed the sourer of some unique field problems. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 10]
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Some manganese oxides are considered hyperactive under microwave irradiation because of their extremely high heating rates in air. In order to further understand this hyperactivity, thermodynamic calculations, thermogravimetric an...
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Some manganese oxides are considered hyperactive under microwave irradiation because of their extremely high heating rates in air. In order to further understand this hyperactivity, thermodynamic calculations, thermogravimetric analysis and both real and imaginary permittivity determinations were performed for hausmannite (Mn3O4) as a function of temperature in an air atmosphere. The thermodynamic results demonstrated reasonable agreement with the thermogravimetric analysis data. A comparison of the derivative thermogravimetric analysis data with the derivative of both the real and the imaginary permittivities confirmed that the extremely high values of the permittivities were due to the conversion of the hausmannite to bixbyite (Mn2O3). The microwave hyperactivity of the manganese oxides in air is explained in terms of the high permittivities of bixbyite.
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摘要 :
Some manganese oxides are considered hyperactive under microwave irradiation because of their extremely high heating rates in air. In order to further understand this hyperactivity, thermodynamic calculations, thermogravimetric an...
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Some manganese oxides are considered hyperactive under microwave irradiation because of their extremely high heating rates in air. In order to further understand this hyperactivity, thermodynamic calculations, thermogravimetric analysis and both real and imaginary permittivity determinations were performed for hausmannite (Mn3O4) as a function of temperature in an air atmosphere. The thermodynamic results demonstrated reasonable agreement with the thermogravimetric analysis data. A comparison of the derivative thermogravimetric analysis data with the derivative of both the real and the imaginary permittivities confirmed that the extremely high values of the permittivities were due to the conversion of the hausmannite to bixbyite (Mn2O3). The microwave hyperactivity of the manganese oxides in air is explained in terms of the high permittivities of bixbyite.
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