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Abstract  

The thermal behavior of poly(methyl methacrylate) (PMMA) was studied in the presence of AlBr3 using TG-DTA-DTG, IR and Py-GC-MS techniques. Degradation products were identified. It was found that PMMA started degrading at a lower temperature due to the generation of free radicals (Br), being the product of decomposition of AlBr3. Despite early destabilization of the system, stabilization zone was also highlighted. Flammability test was conducted to check the affectivity of AlBr3. Degradation mechanism has been proposed. Pyrolysis of the system (PMMA–AlBr3) was also monitored by heating it at different temperatures.

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Transformations de la phase supraconductrice a haute T c (Bi,Pb)2Sr2CaCu2O8+x

Etude des variations de stoechiométrie d'oxygène par optimisation de l'analyse thermogravimétrique

Journal of Thermal Analysis and Calorimetry
Authors: P. Satre and A. Sebaoun

Abstract  

DTA-DTG systematic study of highT c superconducting phase (Bi,Pb)2Sr2CaCu2O8+x, with and without lead, shows a quantitatively opposite variation of oxygen stoechiometry on heating and cooling. Multiplate sample container, designed for the study, allowed to dissociated PbO loss from oxygen variations. Phases transformations have been studied under severalP O2 by scanning DTA and DTG. Oxygen variations evolution has been evaluated by isothermal TG. The results proved that phase diagram representation must take into consideration theP O2 coordinate.

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Abstract  

The oxygen exchange between the condensed phase(s) and the gas phase was studied as a function of temperature for superconducting phases of the system (Bi,Pb)-Sr-Ca-Cu-O. An oxygen probe apparatus allowed confirmation that the variation in oxygen composition in the Pb2212 and Pb2223 superconducting phases is a reversible phenomenon on heating and cooling. It was demonstrated that the mass loss of both phases, for the 905 and 980°C isotherms, was due to the oxygen composition variation and to PbO loss (this latter phenomenon begin irreversible).

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then the cubes were kept in water at 20 ± 1 °C until testing. The CC were studied on their 28- and 90-day compressive strengths and characterized by X-ray diffractometry (XRD), thermal analysis (TG/DTA/DTG), mercury intrusion porosimetry (MIP) and

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The hydration reactions of calcium aluminate in water and in Na2CO3 solution have been investigated using calorimetric, DTA, DTG and XRD methods.

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Journal of Thermal Analysis and Calorimetry
Authors: R. Queiroz, Luiza Pires, Ruth de Souza, J. Zamian, A. de Souza, G. da Rocha Filho, and C. da Costa

Abstract  

Hydrotalcite was synthesised by co-precipitation method, calcined and characterized by XRD, BET, IR and TG/DTA/DTG analyses and tested as solid base catalyst in the transesterification of soybean oil with methanol, achieving a methyl ester content of 99.5%. The thermal decomposition of hydrotalcite calcined occurred in four mass loss steps at 28, 105, 203 and 400 °C. The hydrotalcite was recovered and through a simple evaluation by TG/DTA/DTG techniques it was found that at 500 °C is the temperature, where the organic matter should be eliminated from the catalyst. This study shows the importance of thermal analysis in the evaluation of the recovery temperature of hydrotalcite.

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Abstract  

The temperature range of phase transitions has been established for coal–tar pitches modified with various types of polymers. Mass loss rate was determined in relation to modifying polymer type. Simultaneous thermoanalytical method (DTA, DTG, TG), appeared to be very useful in studies on pitch-polymer compositions.

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Abstract  

Matrix isolation of ferroelectric BaTiO3 nanoparticles was executed by formation of protective silica shell (via hydrolysis and polycondensation of tetraethyl orthosilicate) on particles of precursor—barium titanyl oxalate. Synthesized BaTiO3–SiO2 composites have been characterized by IR spectroscopy, XRD, TEM, DTA/DTG methods.

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Abstract  

Single crystals of pure and neodymium doped calcium hydrogen phosphate were grown in sodium meta silicate gels, by the single diffusion gel method. Platelet and needle shaped crystals were obtained. The grown crystals were characterized by different techniques. The thermal behaviour of the crystals was studied using the thermo analytical techniques, which included TG, DTA, DTG and DSC. These studies reveal that the decomposition of the material occurs in one or more stages. The enthalpy value is also calculated.

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Abstract  

Thermal decomposition of tetrabutylammonium bromotrichloro-, tribromochloro-and tetrabromoferrates(III), of general formula [(n-C 4H9)4N][FeBr4−nCln] (n = 0, 1, 3), has been studied using the TG-MS, DTA, DTG as well as DSC techniques. The measurements were carried out in an argon atmosphere over the temperature range 293–1073 K. Solid products of the thermal decomposition were identified by X-ray powder diffractometry.

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