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Abstract  

The binary manganese and calcium dihydrogen phosphate monohydrate Mn0.5Ca0.5(H2PO4)2 · H2O was synthesized by a rapid and simple co-precipitation method using phosphoric acid, manganese metal, and calcium carbonate at ambient temperature. Thermal transformation shows complex processes and the final decomposed product was the binary manganese calcium cyclotetraphosphate MnCaP4O12. The activation energies of some decomposed steps were calculated by Kissinger method. Activated complex theory has been applied to each step of the reactions and the thermodynamic functions are calculated. These values for transformation stages showed that they are non-spontaneous processes without the introduction of heat. The differences of physical and chemical properties of the synthesized compound and its decomposed product are compared with M(H2PO4)2 · H2O and M2P4O12 (M = Mn and Ca), which indicate the effects of the presence of Ca ions in substitution of Mn ions and confirm the formation of solid solution.

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curing of thermo-setting resins is generally rather complex due to the interaction between chemical kinetics and the simultaneous changes in their physical properties and the development of mechanical properties of the solid material [ 18 ]. The

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these to show no absorption in the visible region. Hence, for following the kinetics, the absorbance changes were recorded at 473 nm at which only the intermediate C 4 absorbs. Fig. 1 Rapid UV–VIS scan of

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eq /dT ≠ 0 because Eq. ( 22 ) is valid and flow of mass and heat occurs. Therefore, this condition can be considered as stationary, but not equilibrium. We analyze the kinetics in dynamic conditions ( q > 0) [ 10 , 11 ]: 23 where K α is

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degradation kinetics and mechanism of BO6 must be fully understood for successful use in manufacture and elevated temperature applications. Thermogravimetric analysis (TG) has been widely used to determine the kinetic parameters of the degradation

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reaction temperature among other process parameters. The most important macroscopic phenomena are gelation and vitrification that occur along the thermoset curing [ 3 ]. The cure kinetics occurs along the alteration of the material rheological pattern

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kinetics and mechanism of thermal decomposition of studied compounds can provide valuable information on the behavior of their hazardous nature. Experimental Synthesis of compounds To the clear solution

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Journal of Thermal Analysis and Calorimetry
Authors: Lech Nowicki, Anna Antecka, Tomasz Bedyk, Paweł Stolarek, and Stanisław Ledakowicz

reagent forming additional amounts of synthesis gas. Apart from being used as potential fuel, the product of gasification, synthesis gas is a useful raw material for chemical industries. Char gasification kinetics depends on the gasifying agent

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Abstract  

The kinetics of gypsum dehydration in non-isothermal conditions with constant heating rate as well in quasi-isotherm, quasi-isobar regime, was investigated. The latter ones of these methods allowed putting in evidence the autocatalytic character of the dehydration, as well as the change of the activation energy with the conversion.The activation energy change was explained by the crystal growth and sample compaction observed by optical microscopy.Microscopic observations show that at higher conversions a compaction occur. This process is probably favoured by the accumulation of the water vapour from the dehydration (autogenerate atmosphere). These are the reason for step III characterised by higher activation.

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Journal of Thermal Analysis and Calorimetry
Authors: Blaž Likozar, Romana Cerc Korošec, Ida Poljanšek, Primož Ogorelec, and Peter Bukovec

–urea–formaldehyde (MUF) resins Curing kinetics of MUF resins has not been studied extensively up to date. Higuchi et al. [ 2 ] proposed a model in which the melamine residues, incorporating a small amount of urea residues, form a three

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