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Abstract  

A novel thermokinetic research method for determination of rate constants of simple-order reaction in batch conduction calorimeter under isothermal condition, the characteristic parameter method, is proposed in this paper. Only needing the characteristic time parameter tm obtained from the measured thermoanalytical curve, the kinetic parameters of reactions studied can be calculated conveniently with this method. The saponifications of ethyl propionate and ethyl acetate in aqueous ethanol solvent, the polymerization of acrylamide in aqueous solution, the ring opening reaction of epichlorohydrin with hydrobromic acid have been studied. The experimental results indicate that the characteristic parameter method for simple-order reaction is correct.

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Abstract  

According to the theoretical basis of thermokinetics, the integral and differential thermokinetic equations of opposing reactions have been derived, and a novel thermokinetic research method, the characteristic parameter method for opposing reactions which taking place in a batch conduction calorimeter under isothermal condition, has been proposed in this paper. Only needing the characteristic thermoanalytical data corresponding to tm and 2tm from the same curve, the rate constants of forward and backward reactions and equilibrium constant can be calculated simultaneously with this method. In order to test the validity of this method, the proton-transfer reactions of nitroethane with ammonia at 15 and 25°C, and with trihydroxymethyl aminomethane (Tris) at 15 and 30°C have been studied, respectively. The results of rate constants and equilibrium constants calculated with this method are in agreement with those in the literature. Therefore, the characteristic parameter method for opposing reaction is believed to be correct.

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Abstract  

Temperature programmed combustions (TPC) of Yang-Quan anthracite, Liao-Cheng lean coal and Li-Yan bituminous coal in oxy-fuel atmosphere were conducted in a thermogravimetric analyzer and characteristic parameters were deduced from the TG-DTG curves. The results showed that combustion got harder to progress as the coalification degree increasing. Within range of 40%, effect of heightening O2 concentration favored the combustion process, but beyond this zone, the effect leveled off. The model-fitting mathematical approach was used to evaluated the kinetic triplet (f (α), E, A) through Coats–Redfern method. The calculation showed that D 3-Jander was the proper reaction model and the evaluations of E and A validated the experimental results.

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:60 PES–PEES on the properties of several epoxy blends cured by 1,5-naphthalenediamine (ND). We determined here the glass transition temperature, as well as characteristic parameters of decomposition, initial decomposition temperature ( T i ) and

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Abstract  

The formation of TiO2 prepared by hydrolysis method was presented. Thermodynamics and kinetics of anatase crystallization reaction were investigated. Differential method of kinetic data evaluation in non-isothermal conditions according toKissinger, Ozawa and Kazeev-Yerofeev was applied. Starting, crystallized and thermally treated powders were determined using X-ray powder diffraction analysis. The characteristic parameters (the activation energy, constant rate and formal kinetic order of reaction) of TiO2 formation were calculated using DSC data.

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Abstract  

On the basis of the theory of thermokinetics proposed in the literature, a novel thermokinetic method for determination of the reaction rate, the characteristic parameter method, is proposed in this paper. Mathematical models were established to determine the kinetic parameters and rate constants. In order to test the validity of this method, the saponifications of ethyl benzoate, ethyl acetate and ethyl propionate, and the formation of hexamethylenetetramine were studied with this method. The rate constants calculated with this method are in agreement with those in the literature, and the characteristic parameter method is therefore believed to be correct.In the light of the characteristic parameter method, we have developed further two thermo-kinetic methods, the thermoanalytical single and multi-curve methods, which are convenient for simultaneous determination of the reaction order and the rate constant. The reaction orders and rate constants of the saponifications of ethyl acetate and ethyl butyrate and the ring-opening reaction of epichlorohydrin with hydrobromic acid were determined with these methods, and their validity was verified by the experimental results.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: Yong-Sam Chung, Sun-Ha Kim, Jong-Hwa Moon, Sung-Yeol Baek, Young-Jin Kim, Hark-Rho Kim, Il-Jin Park, and Kyung-Sik Min

Abstract  

A fast pneumatic transfer system for an instrumental neutron activation analysis and delayed neutron counting system were reconstructed with new designs of a functional improvement at the HANARO research reactor in 2006. The design, conception, operation and control of these systems are described. Also the experimental characteristic parameters by a functional operation test and an irradiation test of these systems, such as the transfer time, the neutron flux, the temperature of the irradiation position with an irradiation time, the radiation dose rate when the rabbit is returned, etc., are reported to provide a user information as well as for the management and safety of the reactor.

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Abstract  

The object of this work is the quantitative explanation of linear correlation between activation energy (E), initial decomposition temperature (T i) and ionic potential (V i), observed for thermal degradation of some complexes of transitional metals. The proposed model allowed the evaluation of characteristic parameter proportional to the activation free enthalpy and also the variation of effective electrical charge (ΔQ *) of ligand, in the formation process of the activated complex. These results are satisfactory, taking into account that we utilized many simple hypotheses for deduction of Arrhenius equation.

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Journal of Thermal Analysis and Calorimetry
Authors: V. Muşat, P. Budrugeac, R. Monteiro, E. Fortunato, and E. Segal

Abstract  

The isoconversional methods (Friedman (FR), Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS)) were applied for evaluating the dependencies of the activation energy (E) on the mass loss (Δm) corresponding to the non-isothermal decomposition of two Zn acetate-based gel precursors for ZnO thin films whose preparation differs by the drying temperature of the liquid sol-precursor (125°C for sample A, and 150°C for sample B). Although both investigated samples exhibit similar decomposition steps, strong differences between E vs. Δm curves as well as among the characteristic parameters of the decomposition steps, directly evaluated from TG, DTG and DTA curves, were put in evidence.

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Abstract  

A surface complexation model, the so-called diffuse double layer model (DLM), was used in the description of the multicomponent system consisting of Czech sodium bentonite SABENYL and synthetic granitic water spiked with233U(VI). The experimental data were evaluated and the characteristic parameters, e.g., the equilibrium constants of all the reactions considered, were obtained and used for the numerical simulation of sorption selectivity of the uranium in relation to the total carbonate concentration. The values of separation factors indicate that the selectivity of uranium sorption in such multicomponent systems can depend not only on the pH and composition of both phases, but also on the phase ratio and starting concentrations of participating components.

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