Determination of thermokinetic parameters and thermodynamic functions from thermoforming of LiMnPO<Subscript>4</Subscript>

This article presents the determination of thermokinetic parameters and thermodynamic functions from the thermoforming of LiMnPO₄. In our previous paper, a couple of thermoreaction processes, e.g., co-elimination and polycondensation of thermokinetics and thermodynamics, were incompletely determined. The co-elimination process is considered as dehydration and a deammoniation process in this paper. Evidently, an alternative technique was applied for calculating the extent of conversion values using the ratio of the peak area of the deconvoluted DTG peak after applying the Fraser–Suzuki deconvolution. An iterative equation of the integral isoconversional technique was used to estimate the reliable activation energy E_α. Each separated peak, including dehydration, deammoniation, and polycondensation, was obviously evaluated as a single kinetic process with its own kinetic parameters. In order to choose reliable mechanisms, the y(α) master plots or the plots between the experiment and the model were compared. The plots thus obtained showed that the dehydration, deammoniation, and polycondensation processes were found to be 3/2-order chemical reaction (F_3/2), 2-order chemical reaction (F₂), and nucleation (P_3/2) mechanisms, respectively. The pre-exponential factor values were obtained from E_α, and the reaction mechanisms were found to be 3.78?×?10¹², 7.05?×?10¹², and 1.96?×?10¹³ s^?1, respectively. The evaluated thermodynamic data of the activated complexes showed that the thermal reaction required thermal energy to complete the reaction.     

An evaluation on thermokinetic parameters for hydrogen peroxide at various concentrations by DSC

Information about the kinetics and thermal decomposition of hydrogen peroxide (H₂O₂) has been required for safety reasons, due to its broad applications in many chemical industries. To determine the inherent hazards during H₂O₂ manufacturing, transportation, disposal, usage, and so on, this study deliberately selected various H₂O₂ concentrations and analyzed them by differential scanning calorimetry (DSC). In addition, thermokinetic parameters were not only established for each of these reactions, but also aimed at comprehensive, kinetic models with various tests conducted at different heating rates. To build up a comprehensive kinetic model, various tests were conducted by heating rates of 1, 2, 4, 10°C min^–1, respectively. According to dynamic DSC tests, the experimental curves show that H₂O₂ decomposition has one exothermic peak and may start to decompose under 47–81°C. The total heat of decomposition is about 192–1079 J g^–1. Not only can these results prevent accidents caused by H₂O₂ during storage and transportation, but also assess its inherent hazards and thereby design procedures for emergency response while runaway reactions occurring.     

Thermogenesis: Relative kinetic limits

This work presents kinetic limits for conduction calorimeters taken from experimental data and given in reduced units (ν τ₁). Two different criteria are proposed concerning either a full reconstruction of a rectangular heat pulse (used in calibration procedures) or a complete separation of elementary pulses to provide a fair reconstruction of the thermogenesis. These upper limits are given for several signal to noise ratios.     

Calorimetry for thermokinetic determinations

The possibilities of using direct calorimetric measurements for the determination of kinetic parameters of processes are discussed in terms of the choice of an appropriate method of reproduction of the course of changes in the heat power generated in time, i.e. thermokinetics. Such methods are presented and it is concluded that many of these methods permit reproduction of the thermokinetics in the same way as if the experimental thermal curve were obtained in a calorimetric system characterized by a time constant 100–200 times as large as that for the thermal inertia of this calorimetric system.

---

Zusammenfassung Die Möglichkeiten zur Benutzung direkter kalorimetrischer Messungen zur Bestimmung kinetischer Parameter von Prozessen werden hinsichtlich der Wahl geeigneter Methoden zur Reproduzierung des Verlaufs der Änderungen der Wärmekraft mit der Zeit, d.h. zur Reproduzierung der Thermokinetik diskutiert. Solche Methoden werden angeführt und es wird die Schlussfolgerung gezogen, dass viele dieser Methoden die Reproduzierung der Thermokinetik auf gleiche Weise wie in den Fällen erlauben, in denen die thermische Kurve mit einem kalorimetrischen System erhalten wird, dessen Zeitkonstante um 100–200mal grösser als die des diskutierten Systems ist.

---

. . . , , , 100–200 .

---

---

Presented at the 2nd Czechoslovak Conference on Calorimetry, Liblice, Czechoslovakia, 1982.     

Non-isothermal thermokinetic of cement hardening

Thermokinetic analysis of cements hydration under nonisothermal conditions was performed. The influence of the application moment, intensity and duration of heat effect on the velocity and completeness of the character of hydration was estimated.     

Mathematical analysis of thermokinetic curves

Journal of Thermal Analysis and Calorimetry - For every actual thermokinetic curve described by the equation $$\frac{{d\alpha }}{{dT}} = (1 - \alpha )^n \frac{A}{q}\exp \left( { - \frac{{ -...     

Microcanonical modeling of the thermokinetic method

A microcanonical analysis of the thermokinetic method is performed using statistical rate calculations based on orbiting transition state theory in order to model a proton transfer process: MH(+) + B(i) --> M + B(i)H(+). The reaction efficiency is calculated as a function of the difference in zero point energy of reactants and products. Several models of reactions were investigated in order to simulate situations where the base of interest M exhibits loss of entropy upon protonation of up to approximately 40 J mol(-1) K(-1). It is shown that the standard thermokinetic method would predict correct 298 K gas phase basicities, GB(298)(M), even for polydentate molecules M, if experiments are conducted at this temperature. Proton affinity, PA(298)(M), and protonation entropy may be obtained by the thermokinetic method only in special circumstances such as, for example, experiments conducted at various temperatures.     

Influence of neodymium on mitochondrial metabolism: a thermokinetic perspective

Journal of Thermal Analysis and Calorimetry - Nd compounds have been widely used for the promotion of growth of plant due to their excellent biophysical and biochemical properties. Mitochondria are...     

Thermogenesis: Identification by means of modulating functions

This paper describes how to obtain an analytic approximation to the transfer function of a conduction calorimeter, namely a procedure to identify the calorimetric system. In this case modulating functions are used directly on the thermogram. The method is used twice: to obtain the time constants and the amplitudes. Its feasibility is tested on two models which span the frequency range usually attained by actual calorimeters. The influence of random noise and baseline drift have also been analyzed. The results show that three or four time constants are correctly obtained.     

Thermogenesis: Identification by means of pade approximants

The paper describes how to obtain an analytic approximation to the transfer function of a conduction calorimeter, namely, a procedure to identify the calorimetric system. In this case Pade approximants are used on the Laplace transform of the thermogram. The feasibility of the method is tested on two models which span the frequency range usually attained by actual calorimeters. The influence of random noise and baseline drift have also been analyzed. The results show that three or four time constants are correctly obtained.     

Isothermal versus non-isothermal calorimetric technique to evaluate thermokinetic parameters and thermal hazard of tert-butyl peroxy-2-ethyl hexanoate

Liquid organic peroxides have been broadly employed in the process industries such as tert-butyl peroxy-2-ethyl hexanoate (TBPO). This study investigated the thermokinetic parameters of TBPO, a typical liquid organic peroxide, by isothermal kinetic algorithms and non-isothermal kinetic algorithms with thermal activity monitor III, and differential scanning calorimetry, respectively. An attempt has been made to determine the thermokinetic parameters by simulation software, such as exothermic onset temperature (T ₀), maximum temperature (T _max), decomposition (?H _d), activation energy (E _a), self-accelerating decomposition temperature, and isothermal time to maximum rate (TMR_iso). A liquid thermal explosion model was established for a reactor containing liquid organic peroxide of interest. From experimental results, liquid organic peroxides?? optimal conditions for avoiding a violent runaway reaction of storage and transportation were created.     

绝热式热动力学的研究III:二级反应的热谱解析

本文建立了二级发应在绝热系统中的热动力学研究, 并用自制的绝热式自动量热计, 研究了几个放热反应体系的热动力学, 而且对吸热反应体系的热动力学研究进行了探索。     

Phenomenological thermokinetic analysis of coffee husk pyrolysis: a study case

Journal of Thermal Analysis and Calorimetry - The thermokinetic analysis of the pyrolytic degradation of coffee husk reveals that the degradation path of its main pseudo-components at the maximum...     

Study on the thermokinetic properties of bacterial growth

The power-time curves of bacterial growth at different temperatures were determined by using the 2277 Thermal Activity Monitor (Sweden). From these curves, the growth rate constant () and activation energy (E _a) were calculated. According to the transition state theory of reaction dynamics, the activation entropy (S), activation Gibbs free energy (G) and equilibrium constant (K ) of the activation state could be calculated. These results permitted thermodynamic analysis of the bacterial growth metabolism.Supported by the Natural Science Foundation of Shandong Province.     

Thermogenesis of Artemia in post-dormant development

Isothermal microcalorimeter was modified to measure slow and weak thermal dissipation for developmental and evolutionary biology. The calorimeter can detect the continuous thermal dissipation of the ampoule at P=20 nW and fast thermal events with E=0.1 μJ. Baseline was stabilized to be ±10 nWover a week. By using this calorimeter, post-dormant development of a single larva of Artemia franciscana (Great Salt Lake) was measured as a function of incubation time at T=293.17 K. Characteristic thermogenesis was observed at emergence, hatching and growth. The energy of yolk in a cyst was evaluated to be 38 mJ in average on the basis of the total thermogenesis of a larva.     

镨配合物的热化学及其对酵母菌作用的热动力学研究

用六水合氯化镨、硫代脯氨酸(C4H7NO2S)和水杨酸(C7H6O3)合成了三元固体配合物[Pr(C7H5O3)2(C4H6NO2S)]-2H2O.根据盖斯定律设计一个热化学循环,用溶解-反应量热法研究得到合成反应的标准摩尔焓变为(133.70±1.02)kJ/mol,配合物298.15K时的标准摩尔生成焓为-(2909.3±3.2)kJ/mol.用TAMair微量热仪测定其在28.00℃时对粟酒裂殖酵母作用的产热曲线,进而算出在配合物作用下,酵母菌生长代谢的最大发热功率Pmax、速率常数κ、传代时间tG、抑制率I和半抑制浓度cI,50等热动力学参数.结果表明:稀土水杨酸硫代脯氨酸配合物在低浓度下对酵母菌有刺激作用,高浓度下为抑制作用,即稀土配合物对微生物的生长具有双向生物效应,也称为Hormesis效应.     

Thermogenesis: Smoothing techniques in Z-transform and harmonic analysis

This work analyses how the standard smoothing techniques affect the thermogenesis given by harmonic analysis or Z-transform methods. The analysis has allowed an optimization of their efficiency. The results concerning signal/noise ratios of 40, 60, 80 and 100 dB are tabulated and generalized to a reduced frequency representation.     

Mathematical analysis of thermokinetic curves for autocatalytically decomposing substances

The mathematical analysis of thermokinetic curves described by the differential equation dα/dt=Kα(1?α) has been performed, and an integral expression for this equation was obtained.     

Thermochemical properties and thermokinetic behavior of energetic triazole ionic salts

The properties of dissolution in different solvents,the specific heat capacity and thermal decomposition process under the non-isothermal conditions for energetic triazole ionic salts 1,2,4-triazolium nitrate(1a),1,2,3-triazolium nitrate(1b),3,4,5triamino-1,2,4-triazolium nitrate(2a),3,4,5-triamino-1,2,4-triazolium dinitramide(2b)were precisely measured using a Calvet Microcalorimeter.The thermochemical equation,differential enthalpies of dissolution(△difH m ),standard molar enthalpies of dissolution(△difH ...