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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.
Abstract
The dehydration and decomposition bauxite mixed with alkaline compounds were investigated under dynamic and isothermal conditions. Alkaline compounds (CaO or/and Na2CO3) were added to bauxite samples in various mole fractions (0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 of CaO). To determine the effect of alkaline additives on the thermal properties of bauxite, TG, DTG and DTA techniques were used simultaneously under atmospheric conditions.
Abstract
The effects of basic fibre-forming parameters on the thermal properties and flammability of fibres from polyimidoamide (PIA) nanocomposite have examined. The comparative analysis of the properties of fibres from modified PIA and PIA nanocomposite has been conducted. The multi-functional fibres prepared from PIA nanocomposite show increased porosity and sorption properties as well as a high thermal stability and reduced flammability in comparison with fibres without MMT.
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.
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.
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.
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.
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.
Abstract
Thermal properties of cis-1,4-poly(butadiene), Europrene cis, were investigated by means of thermal analysis and complementary methods. Thermal analysis of polymer was carried out both in air and inert atmosphere with a derivatgraph, DSC and internal TG-FTIR coupling system as well as internal TG, DTA-MS coupling system. It was found that investigations in air atmosphere the method of the sample preparation ofcis-1,4-poly(butadiene) influences the results of thermal analysis, which is connected with the rate oxygen diffusion into the reaction zone. Taking into consideration both the method of the sample preparing and atmosphere of thermal studies, the values of activation energy of destruction of cis-1,4-poly(butadiene) were determined. Using TG-FTIR and TG-MS methods, some products of thermal destruction of elastomer were determined.
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.
