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Summary Many of Sydney’s heritage buildings and monuments were built as a result of the first European settlement in the 1800s. These buildings not only display the richness of the Australian culture, but also capture the architectural and historical values of its past. Although many of these buildings still appear to be strong and sound, many signs of deterioration have been detected in recent years. Conservators from various disciplines such as science, architecture and engineering are working closely together to develop suitable solutions to stop or at least slow down the degradation process of these precious buildings. This study demonstrates the usefulness of thermal analysis in determining the weathering mechanisms of marble and sandstone taken from two of Sydney’s landmarks, the Captain Arthur Phillips Monument at Sydney’s Botanic Gardens and Sydney’s St Mary’s Cathedral. This paper reports the findings of the weathering behaviours of both marble and sandstone samples determined using thermal analysis techniques.

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Thermal analysis of thione compounds

I. The thermal behaviour of thiourea and N-methylthioureas

Journal of Thermal Analysis and Calorimetry
Authors: D. De Marco, R. Bucci, and C. Gallo

The thermal behavior of thiourea (Tu), N-methylthiourea (MeTu), N, N′-dimethylthiourea (Me2Tu) and N, N, N′, N′-tetramethylthiourea (Me4Tu) was investigated by means of conventional thermal analysis in O2 and N2 and IR spectroscopy of the residues on heating in air at various temperatures.

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Abstract  

A method has been developed using thermoanalytical techniques for the analysis of residues from coal-burning fluidised bed plant where limestone is used as a sulphur scavenger. This completely eliminates the need for lengthy wet chemical analyses and allows the derivation of parameters necessary for efficient plant operation, such as limestone addition rate, calcium utilisation efficiency and calcium to sulphur mole ratio. The method also gives values for the unburned carbon content and the ratio of coal ash to limestone derivatives in the sample.

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Abstract  

Thermogravimetric analysis of synthetic smithsonite and hydrozincite, two secondary minerals of zinc, was used to determine their relative thermal stability. Thermal decomposition of smithsonite occurs at 293°C and hydrozincite at 220°C showing that the carbonate mineral is more stable than the hydroxy-carbonate mineral hydrozincite. Hot stage Raman spectroscopy confirms the decomposition of smithsonite and hydrozincite by 300 and 250°C, respectively. Thermogravimetry shows that a small amount of hydrozincite is formed during the synthesis of smithsonite. No evidence is found for the separate loss of the carbonate and hydroxyl units from hydrozincite.

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Abstract  

Thermogravimetric (TG) and differential thermal analysis (DTA) curves of methyltributylammonium smectite (MTBAS), methyltrioctylammonium smectite (MTOAS), and di(hydrogenatedtallow)dimethylammonium smectite (DHTDMAS), and also corresponding sodium smectite (NaS) and tetraalkylammonium chlorides (TAAC) were determined. The TAACs was decomposed exactly by heating up to 500°C. The adsorbed water content of 8.0% in the pure NaS was decreased down to 0.2% depending on the size of the non-polar alkyl groups in the tetraalkylammonium cations (TAA+). The thermal degradation of the organic partition nanophase formed between 2:1 layers of smectite occurs between 250–500°C. Activation energies (E) of the thermal degradations in the MTBAS, MTOAS and DHTDMAS are 13.4, 21.9, and 43.5 kJ mol−1, respectively. The E value increases by increasing of the interlayer spacing along a curve depending on the size of the alkyl groups in the TAA+.

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Oxathioamidates (CSNR1 R 2COOKR 1=R 2=H (A),R 1=H andR 2=CH3 (B),R 1,=R 2=CH3 (C)) can act as O, S donors and form pentaatomic ring systems with divalent metals (M(II)=Mn, Fe, Co, Ni, Cu, Zn). Vibrational spectra and thermal analysis provide information on the amount and nature of associated water molecules. The dehydration of MA2(H2O)2 (M=Mn, Fe, Co, Ni) can be very well explained by the C.F.S.E. (crystal field stabilization energy) for weak field octahedral complexes. The complexes with ligand A and B decompose to form polymers by deprotonation on the thioamide group. The proposed structures are confirmed by the vibrational spectra. For ligand C no stable intermediates are formed during heating, degradation proceeds until metal sulphide remains.

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Thermal analysis of diazo pigments

II. Derivatives of 1,4-bis-(8′-hydroxy-3′,6′-disulpho-1′-naphthyl)-benzene-diamide

Journal of Thermal Analysis and Calorimetry
Authors: G. Simeonov, A. Draganov, and D. Ructschev

Abstract  

The differential-thermal and thermogravimetric analysis of eight derivatives of 1,4-bis-(8′-hydroxy-3′,6′-disulpho-1′-naphthyl)-benzenediamide showed that these compounds have a marked exothermic effect, with maxima in the temperature range 290–340°C. The 4-nitroaniline derivative was found to undergo a blast-like decomposition in the temperature interval 285–295°C, reflected by large steps in the TG curves. The thermal analysis of diazo pigments permits determination of their applicability at higher temperatures.

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thermal analysis (DTA) and derivative thermogravimetry (DTG) methods [ 8 , 9 ]. Thermal analysis plays important role in structure and stability studies of both organic and inorganic compounds [ 10 – 12 ]. TG analysis is a valuable tool for the

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Thermal analysis of pharmaceutical compounds

III. Characterization of sulphonamides by thermal analysis

Journal of Thermal Analysis and Calorimetry
Authors: F. I. Khattab, N. Y. M. Hassan, and M. M. Amer

Fourteen sulphonamides have been thermally analyzed using thermogravimetry (TG), derivative thermogravimetry (DTG) and differential thermal analysis (DTA). Their thermal reactions and stabilities have been thoroughly studied. It was found that the sulphonamides are first transformed into sulphanilamide. The melting points of these sulphonamides have been determined through their DTA curves and by the Kofler microscope, the results agreeing with those reported in the literature. The amount of water of crystallization has been calculated from the TG and DTG curves. Analysis of mixtures of some sulphonamides has been achieved by thermal analysis and by thin-layer chromatography using different solvent systems.

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reported to show that there is a reduction in Ca(OH) 2 content [ 14 ]. Little is known however, in terms of the effect thereafter and that no full investigation of the system have been found using both thermogravimetric and differential thermal analysis

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