Structural and thermal studies on the solid products in the system MnSeO3-SeO2-H2O

Vlaev, L. T.; Tavlieva, Mariana P.

doi:10.1007/s10973-007-7748-x

Cited by 10 publications

(13 citation statements)

References 28 publications

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“…The higher and positive values of ΔS ≠ observed for treated composites may indicate that is necessary a more significant rearrangement in the treated composites structure with the formation of the activated complex. 32,33…”

Section: Resultsmentioning

confidence: 99%

Effects of the coupling agent structure on the adhesion of recycled polystyrene wood flour composites: Thermal degradation kinetics and thermodynamics parameters

Poletto

2016

Journal of Composite Materials

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Recycled polystyrene wood flour composites were developed with three different polystyrene maleic anhydride oligomers used as coupling agents. The thermal properties, morphology, kinetics, and thermodynamic parameters were investigated. The use of oligomers clearly improves the interfacial adhesion with the polymer matrix and increases the thermal stability of the composites. The oligomers with higher maleic anhydride content tend to reduce the composite thermal stability, while oligomers with intermediate quantities of maleic anhydride groups tend to promote a higher composite thermal stability. The thermodynamic results showed that the composite without coupling agent presented the lowest entropy value, which indicates that the thermal decomposition in this composite is slow. However, the entropy values and frequency factor increased when coupling agents were used. The addition of coupling agents likely changed the state near to the thermodynamic equilibrium by causing structural disorder, in the system increasing the treated composite reactivity.

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Section: Resultsmentioning

confidence: 99%

Effects of the coupling agent structure on the adhesion of recycled polystyrene wood flour composites: Thermal degradation kinetics and thermodynamics parameters

Poletto

2016

Journal of Composite Materials

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“…Several authors − have suggested different ways to solve the right-hand side integral. The integral methods of the Coats−Redfern (CR), the Madhysudanan−Krishnan−Ninan (MKN), and the Tang et al (TL) have been predominantly and successfully used for studying the kinetics of dehydration and decomposition of different solid substances. − For the present study, calculation procedures were based on the CR, MKN, and TL equations. Data from the TG curves in the decomposition range 0.1 < α < 0.9 were used to determine the kinetic parameters of the process in all used calculation procedures.…”

Section: Resultsmentioning

confidence: 99%

“…They are formed by the calcination of dihydrogenphosphates of bivalent metals or by the calcination of a mixture containing phosphorus and bivalent metal components in the corresponding ratio. − A number of papers have dealt with the use of thermal analysis (TA) under quasi-isothermal, quasi-isobaric conditions to follow the dehydration reactions of some binary metal dihydrogenphosphate hydrates. − So far, however, no report has appeared on the application of kinetic and thermodynamic methods to the investigation of the important condensation products, cyclotetraphosphates. The presence of water molecules of binary dihydrogenphosphate hydrates influences the intermolecular interactions (affecting the internal energy and enthalpy) as well as the crystalline disorder (entropy) and, hence, influences the free energy, thermodynamic activity, solubility, stability, and electrochemical and catalytic activity. − Studies on the thermodynamics, mechanisms, and kinetics of solid-state reactions are a challenging and difficult task with complexity resulting from a great variety of factors with diverse effects such as reconstruction of solid state crystal lattices, formation and growth of new crystallization nuclei, diffusion of gaseous reagents or reaction products, materials heat conductance, and static or dynamic character of the environment, physical state of the reagentsdispersity, layer thickness, specific area and porosity, type, amount, and distribution of the active centers on solid state surface, etc. − The results obtained from such studies can be directly applied in materials science for the preparation of various metals and alloys, cements, ceramics, glasses, enamels, glazes, polymers, and composite materials. − …”

Section: Introductionmentioning

confidence: 99%

Kinetics and Thermodynamics of the Formation of MnFeP₄O₁₂

Boonchom

Thongkam

2009

J. Chem. Eng. Data

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The kinetics and thermodynamics of dehydration and intermolecular polycondensation reactions of Mn1/2Fe1/2(H2PO4)2·H2O and Mn1/2Fe1/2(H2PO4)2 were studied under nonisothermal heating by thermogravimetry (TG). On the basis of three calculation procedures and 24 kinetic mechanism functions, kinetic triplets (E, A, kinetic model) using the Arrhenius equation were calculated for both processes. The comparison of the results obtained with these calculation procedures show a strong dependence on the selection of the mechanism function for the process. The thermodynamic functions (ΔH*, C p , ΔG*, and ΔS*) of both reactions are calculated from differential scanning calorimetry (DSC) experiments. Kinetic and thermodynamic results indicate that the polycondensation step has a lower rate and is a stronger reaction than the dehydration step and corresponds to the breaking of the strong hydrogen-bonded P−OH group, in connection with the polycondensation reaction, which confirms that the decomposition product (manganese iron cyclotetraphosphate, MnFeP4O12) was obtained.

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“…The solubility diagram was plotted according to the Gibbs-Roozeboom method. The approach and characterization method for solid phases was similar to that described in the literature [14][15][16] . 1074 V. GEORGIEVA ET AL.…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

Thermal Stability of Cerium Selenite and Solubility of the System Ce₂O₃–SeO₂–H₂O at 100°C

Georgieva

Stancheva

Genieva

2014

Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-

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The solubility of the three-component system Ce 2 O 3 -SeO 2 -H 2 O was studied at 100 • C. By the Schreinemakers' method, the relevant solubility isotherm was drawn. In the studied system, Ce 2 O 3 -SeO 2 -H 2 O in the concentration range 1.52-15.25 mass% of SeO 2 in the liquid phase was formed anhydrous cerium(III) selenite Ce 2 (SeO 3 ) 3 , and in concentration range 15.25-61.35 mass% of SeO 2 -cerium(III)hydrogen selenite Ce(SeO 3 )(HSeO 3 ), respectively. The obtained phases in the systems were characterized by chemical, X-ray diffraction, and thermogravimetric analysis. The thermal stability and kinetics of decomposition of Ce 2 (SeO 3 ) 3 was studied under non-isothermal heating on a derivatograph. Several mathematical models were used to describe the processed as well as eight different calculation methods. The values of the kinetic parameters strongly depend on the kind of g(α) function, whereas the used calculation procedures have not an influence. On this basis, the values of process activation energy E, pre-exponential factor A in the Arrhenius equation, change of entropy S = , enthalpy H = , and Gibbs free energy G = for the formation of activated complex by the reagent were calculated.

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Structural and thermal studies on the solid products in the system MnSeO3-SeO2-H2O

Cited by 10 publications

References 28 publications

Effects of the coupling agent structure on the adhesion of recycled polystyrene wood flour composites: Thermal degradation kinetics and thermodynamics parameters

Effects of the coupling agent structure on the adhesion of recycled polystyrene wood flour composites: Thermal degradation kinetics and thermodynamics parameters

Kinetics and Thermodynamics of the Formation of MnFeP₄O₁₂

Thermal Stability of Cerium Selenite and Solubility of the System Ce₂O₃–SeO₂–H₂O at 100°C

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Structural and thermal studies on the solid products in the system MnSeO3-SeO2-H2O

Cited by 10 publications

References 28 publications

Effects of the coupling agent structure on the adhesion of recycled polystyrene wood flour composites: Thermal degradation kinetics and thermodynamics parameters

Effects of the coupling agent structure on the adhesion of recycled polystyrene wood flour composites: Thermal degradation kinetics and thermodynamics parameters

Kinetics and Thermodynamics of the Formation of MnFeP4O12

Thermal Stability of Cerium Selenite and Solubility of the System Ce2O3–SeO2–H2O at 100°C

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Kinetics and Thermodynamics of the Formation of MnFeP₄O₁₂

Thermal Stability of Cerium Selenite and Solubility of the System Ce₂O₃–SeO₂–H₂O at 100°C