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Abstract  

The thermal properties are presented for a precious opal sourced from Coober Pedy, South Australia and a moldavite from Bohemia, Czech Republic whose origins differ significantly as opal is derived from the slow isothermal diagenesis of silica, while the tektites are specimens of vitreous silica formed from the terrestrial impact of asteroids. The differences between the two glassy silicates are presented through measurement of the TG–DSC, TMA and high-vacuum-hot-extraction DEGAS analysis.

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Abstract  

The thermal properties of KTN crystal were investigated at low temperatures by DSC and TM. The phase transition enthalpies and the average specific heats of the crystal were measured. Results are analyzed and discussed.

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Abstract  

Hydrazine derivatives of the monobasic nitrilotriacetate salts of zinc and alkaline earth metals have been prepared. IR absorption frequencies and thermal properties of these metal-hydrazinium nitrilotriacetates, (N2H5)M[N(CH2COO)3]·xH2O have been defined. All the three -COOH appear to be dissociated in these salts. In thermal decomposition, these salts initially undergo dehydration followed by dehydrazination and via acetate intermediate step to metal oxycarbonates.

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Summary In this study, the thermal properties of agro-flour-filled polybutylene succinate (PBS) bio-composites were investigated. PBS is one of the biodegradable polymers made from the condensation reaction of glycols and dicarboxylic acid and is naturally degraded by natural soil burial system. The thermal properties of the bio-composites were analyzed according to the agro-flour content and mesh size. On increasing agro-flour content, the thermal stability, degradation temperature and derivative thermogravimetric curve (DTGmax) temperature of the bio-composites decreased while the ash content increased. The thermal degradation of the bio-composites was not affected by agro-flour mesh size. The glass transition (T g) and melting (T m) temperatures of the bio-composites were not significantly changed. The storage modulus (E’) of the bio-composites was higher than that of neat PBS, because the incorporation of agro-flour increased the stiffness of the bio-composites. At higher temperatures, E’ of the bio-composites decreased due to the increasing viscosity and chain mobility of neat PBS. The thermal properties of bio-composites have an important effect on the manufacturing system and application methods.

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Abstract  

Xerogels were prepared from zirconium, barium, aluminum, lanthanum and lithium acetates, corresponding to a Li containing ZBLA composition. The study of their thermal properties (DSC, TG/DTG, FT-IR) showed that they might be used as chemically stable precursors in the preparation of fluoride glasses. Hydrofluoric acid in solution was chosen as a mild fluorinating agent. This newly proposed technique of fluorinating allowed to obtain high quality ZBLALi glass which presents the advantage of higher thermal stability and homogeneity in comparison with the glass obtained using individual commercial fluorides.

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Abstract  

The new zinc ternary complexes [Zn(cyclen)NO3]ClO4 (I), [Zn2(cyclen)2(m-nic)](ClO4)3 (II), [Zn2(cyclen)2(m-pic)](ClO4)3 (III) (cyclen=1,4,7,10-tetraazacyclododecane; nic=nicotinic acid; pic=picolinic acid) were synthesized and their spectral and thermal properties were investigated. The compounds were characterized by elemental analysis, IR spectroscopy and TG/DTG, DTA methods. Moreover, the way of coordination of pyridinecarboxylate anions was proposed on the basis of the spectral data and consequently proved with results of X-ray structure analysis.

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Abstract  

A series of PDPS/PDMS copolymers were synthesized through living anionic polymerization withn-butyllithium as an initiator. The changes of thermal property as a function of PDPS content were compared with respect to different types of monomer sequence using differential scanning calorimetry and thermogravimtery. The results indicated that the related variations of the thermal propertiesvs. the PDPS content and the monomer sequence provided independent operative control for preparing materials with desired thermal properties. The thermal stability of these copolymers was dramatically improved with introducing PDPS segment. However, the degree of these improvement pedended greatly on the monomer sequence in the copolymers.

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The study of thermal properties of La(HV6O16)3.19.5H2O and Y(HV6O16)3.22H2O showed, that the dehydration of both compounds is discontinuous. After release of last water amount, the parent structure is destabilized and products of thermal decomposition, V2O5 and corresponding orthovanadates, start to be formed.

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Abstract  

Since some combustible, oxidative and reductive chemicals are used in the extracting process in the nuclear reprocessing plant the process has potential hazards of a fire and explosion due to the undesired reaction. In this study to obtain a better understanding of the thermal properties of hydrazine in nitric acid solution which is used for preventing the oxidation of extracted plutonium, thermal analysis was carried out for the mixtures in various conditions. From the results of DSC it was revealed that the vessel material has an influence on the thermal decomposition of hydrazine. It was also found that hydrazine reacted with nitric acid in an autocatalytic manner, and concentration of nitric acid has a strong influence on the thermal hazard of hydrazine and nitric acid mixtures.

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Abstract  

The present paper discusses the results of assessing thermal properties of nitrile rubber, Perbunan NT 3945 and its peroxide vulcanizates, before and after their swelling in solvents such as benzene, toluene and dimethylformamide. The measurements were carried out by means of differential scanning calorimetry (DSC) and thermogravimetry (TG) under nitrogen. It has been found that a slight rise in the glass transition temperature due to the elastomer cross-linking is clearly revealed under the influence of its vulcanizates swelling in solvents whose solubility parameters considerably differ from the solubility parameters of the polymer. The thermal curves of swollen samples reveal processes resulting from polymer-solvent interactions and thermodesolvation processes, which accompany the initial stage of solvent evaporation.

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