Search Results

You are looking at 1 - 10 of 103 items for :

  • "thermal analysis (TG-DTA)" x
  • All content x
Clear All
Journal of Thermal Analysis and Calorimetry
Authors: L. Pérez-Maqueda, V. Balek, J. Poyato, J. Pérez-Rodríquez, J. Šubrt, I. Bountsewa, I. Beckman, and Z. Málek

Abstract  

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 25-1100C. 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.

Restricted access

Abstract  

Humic acids (HAs) extracted from soils developed under two Norwegian spruce (Picea abies, (L.) Karst) subalpine forests of northern Italy were characterized using chemical, thermal (TG-DTA) and spectroscopic (DRIFT) analyses. The samples were taken from five sites which differed in orientation (northern and southern exposure) and vegetal cover at different old age: grassland, regeneration, immature and mature stands. In general, the thermal patterns of HAs were similar (three exothermic reactions appeared around at 300, 400 and 500C) in both sites in grasslands and regeneration while a considerable modification appeared in HA from stands of different age at northern and southern exposure site. DRIFT spectroscopy confirmed the differences observed through TG-DTA analysis. In particular the main structural changes were ascribed to modification of carbonyl group and of CH stretching in aliphatic components in each HAs from different sites.

Restricted access

Abstract  

Reaction kinetics of the formation of TiC by calciothermic reduction of TiO2 in presence of carbon have been investigated using thermal analysis (TG-DTA) of a powder mixture of TiO2, Ca, and C in argon atmosphere at different heating rates. Both the reaction initiation and the peak temperatures are found to increase with heating rates. The appearance of exothermic peaks in the DTA plots after Ca melting indicates the reduction of TiO2 by liquid calcium and formation of TiC by in-situ reaction of Ti with C. The apparent activation energy of the process has been found to be 170.80.5 kJ mol-1.

Restricted access

simultaneous thermogravimetry and differential thermal analysis (TG–DTA) systems. The experiments were carried out with ~10 mg, crude oil-limestone sample (15 wt% crude oil in the mixture) at 10 °C/min heating rate. Air flow rate through the sample pan was kept

Restricted access

mode for biguanide derivatives. Thermal analysis (TG, DTA) of these complexes confirms the complexes composition and allows the number and nature of the water molecules determination. It was also evidenced that the intermediate steps correspond

Restricted access

weight and enthalpy during reaction were obvious [ 10 – 15 ]. In this paper, the thermogravimetry–differential thermal analysis (TG–DTA) and Fourier transform infrared spectroscopy (FTIR) were used to real time monitor the reaction process of

Restricted access

the thermal analysis (TG-DTA) the light-curing composites polymerization quality (monomer/polymer), carried out at different times and distances of irradiation (0–8 mm; 20–60 s). Materials and methods The materials used were

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: Mihaela Badea, Rodica Olar, Valentina Uivarosi, Dana Marinescu, Victoria Aldea, Stefania Felicia Barbuceanu, and George Mihai Nitulescu

square-pyramidal stereochemistry for metallic ion was proposed based on the electronic spectra, while the IR spectra features indicated a chelate coordination mode of flavones. Thermal analysis (TG, DTA) of these complexes elucidated the

Restricted access

and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC) and TG coupled to FTIR. Experimental The folic acid (C 19 H 19 N 7 O 6 ) with 99% purity was obtained from Aldrich. Aqueous solution of Na 2

Restricted access

synthesised and characterised. Spectral data indicate a square pyramidal stereochemistry for complexes and a chelate coordination mode for flavonoid molecules. Thermal analysis (TG, DTA) of these complexes confirms the complexes composition and allows

Restricted access