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Abstract  

It has been determined the thermal behaviour at high temperatures of an iron aluminum arsenate mineral first described in the location of La Serena Valley, Extremadura, Spain, which expands until 1173 K contracting later and softening at 1653 K and full melting at 1773 K. The DTA/TG experiment only detects some rearrangement with an endothermic at 1173 K due to the mica mixing. The mineral is a scorodite variety mixed with micaceous clay which has been found as aggregates of pyramidal crystals associated with quartz, wolframite, molibdenite, cassiterite and other secondary minerals in the pegmatite of the San Nicolas mine. The chemical composition, the physico- chemical characteristics such as density and hardness, as well as the thermal behaviour has allowed to conclude that this mineral can be an Al-enriched scorodite (mansfieldite): (Fe, Al) AsO42H2O mixed with illite from the scorodite-mansfieldite series.

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Abstract  

Thermal behaviour of CuS (covellite) obtained from the Cu(CH3COO)2·H2O and Na2S2O3·5H2O system, working at different molar ratio (1:6 and 1:4) in presence/absence of NH4VO3, was studied. It was established that the presence of vanadium in the system induces a densification of CuS nodules, but do not change the hexagonal CuS structure. It has an important influence in thermal behaviour of copper sulfide CuS obtained also. The morphological characteristics of CuS play an important role in the thermal stability and the stoichiometry of the thermal decompositions. Also, the possibility to obtain copper sulfides with greater cooper content was investigated.

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Abstract

Intercalation complexes of three different Hungarian kaolinites with hydrazine and potassium acetate were investigated by FT-IR (DRIFT) spectrometry, X-ray diffraction, and thermogravimetry combined with mass spectrometry. Differences were found in the thermal behaviour of the complexes as well as in the rehydration — reexpansion patterns of the heated intercalates. An XRD method is proposed for the distinction of kaolinite and 7.2 Å halloysite present in the same mineral.

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Abstract  

The paper describes the effect of molecular mass and copolymer composition on thermal behaviour of homopolymers and copolymers of glycidyl methacrylate and methyl methacrylate. The polymerisation was done by using group transfer polymerization (GTP) and free radical techniques. A multistep decomposition was observed in polymers prepared by free radical technique indicating the presence of weak linkages in the backbone. Copolymers prepared by GTP had fewer weak sites and degraded in single step by a random chain scission.

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Abstract  

The thermal behavior of a purified galena in a chlorine surrounding was determined. The kinetic of the chlorination of galena and the stoichiometry of this reaction between 723 to 973 K (450 to 700C) were measured by thermogravimetry. The microstructural characterization of the solid residues were determined by SEM, EDXS and XRD. The ΔH vap of the produced lead chloride volatilization was obtained by the application of Clausius-Clapeyron equation considering the process in an equilibrium state.

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Journal of Thermal Analysis and Calorimetry
Authors: Maria Luisa A. Gonçalves, D. A. Ribeiro, Deusa Angélica P. Da Mota, Ana Maria R. F. Teixeira, and M. A. G. Teixeira

Summary Thermogravimetry (TG) was applied to evaluate the thermal behavior of five refinery atmospheric distillation residues (ATR) obtained from different Brazilian crude oils. The asphaltenes were extracted of each sample and their influence on coke formation was studied. It was observed that they have a great contribution on carbonaceous residues formation during pyrolysis and that the heavier the ATR sample, the higher is the contribution of other heavy components present in ATR samples.

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Benzenesulfenamides with the formula R-S-N-(R′)2 (R=C6H5 andR′=NC4H8O, C7H7 and C6H11) and their chromium carbonyl complexes were studied by means of TG and mass spectrometric methods. The thermal behaviour of the compounds the stabilities of free sulfenamides are lower than those observed for the corresponding chromium carbonyl complexes. Combined thermogravimetry — mass spectrometry results suggest that the fragmentation mechanism of the carbonyl complexes involves cleavage of the Cr-S and Cr-CO bonds while that of sulfenamide depends mainly on the dissociation rates of the NR2 groups.

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Abstract  

Thermal behaviour of blends based on N,N'-bis(4-itaconimidophenyl) ether (IE) and 4,4'-bis(4-allyl-2-methoxyphenoxy) benzophenone (R1) or 4,4'-bis(2-allylphenoxy) benzophenone (R2) are described in this paper. The reactive diluent content was varied from 5-50% (mass/mass) in these blends. A decrease in the melting point and exothermic peak temperature was observed with increasing mass percent of reactive diluent. Thermal stability of blends was affected at high mass percentage of reactive diluents.

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Abstract  

Complexes of Cu(II) with substituted o-acetoxy benzoic acids (5-haloaspirines, X-asp) with and without pyridine (py), of composition [Cu2(X-asp)4] and [Cu(X-asp)2(py)2 ] have been synthesized and characterized. Electronic and vibrational spectroscopic data of these complexes are reported. Its thermal behaviour was investigated by thermogravimetry and differential thermal analysis. In all complexes, the haloaspirinate ligands decompose in two or three steps, starting with the break up of the coordinated acetoxy groups. CuO is obtained as the final pyrolysis residue in all cases.

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