Thermodynamic properties and thermal stability of the synthetic zinc formate dihydrate

The dynamic heating rate method developed by TA Instruments (Hi-Res ™ ) is a kind of sample controlled thermal analysis in which a linear relationship between the logarithm of the heating rate and the rate of weight change is imposed. It is shown in this paper that the reacted fraction at the maximum reaction rate strongly depends on the parameters selected for the Hi-Res heating algorithm, what invalidates the use of the Kissinger method for analysing Hi-Res data unless that the reaction fits a first order kinetic law. Only in this latter case, it has been demonstrated that it is not required that a constant value of the reacted fraction at the maximum reaction rate is fulfilled for determining the activation energy from the Kissinger method. In such a case the Kissinger plot gives the real activation energy, independently of both the heating schedule used and the value of the reacted fraction, α m , at the maximum.

Section: Introductionmentioning

confidence: 99%

Kissinger kinetic analysis of data obtained under different heating schedules

Jiménez

Criado

Pérez‐Maqueda

2008

“…Thermal analysis has been used to study the desolvation, dehydration and polymorphic transformation processes [13][14][15][16][17]. The advantages of using conventional DSC for testing pharmaceutical compounds are the ease of sample W. Liu School of Chemistry and Chemical Engineering, Henan University of Technology, Zhengzhou 450001, People's Republic of China preparation, relatively fast analysis time and the wide temperature range that can be studied.…”

Section: Introductionmentioning

confidence: 99%

Thermal, phase transition, and thermal kinetics studies of carbamazepine

Liu

Dang

Wei

2012

The thermal, phase transition of carbamazepine dihydrate and the solid-state transformation of carbamazepine from form III to form I were performed by Differential scanning calorimetry (DSC), Thermo gravimetry (TG-DTA), and X-ray powder diffraction.The non-thermal kinetic analysis of carbamazepine dihydrate and form III was carried out by DSC at different heating rates in dynamic nitrogen atmosphere. The model-free model, the Kissinger method, was used to give the Arrhenius parameters. Arrhenius plots from the kinetic model yielded activation energies corresponding to dehydration of dihydrate and melting of anhydrate CBZ form I were 95.28, 966.06 kJ mol -1 , the pre-exponential factors were 8.34E?11 and 1.41E?149, respectively. For the transformation of carbamazepine from form III to form I, activation energies corresponding to the melting of CBZ form III, recrystallization of form I, and melting of form I were 1160.81, 710.89, 1265.89 kJ mol -1 , the pre-exponential factors were 2.29E?144, 4.43E?91, and 1.61E?151, respectively. As a comparison, Ozawa method was used to verify the activation energy values obtained by Kissinger method. The result shows a close activation energy values between two methods.

“…The structure and principle of the calorimeter have been described in references [17][18][19][20]. Nowadays, this method has been fully developed for directly determining heat capacities for a large number of materials isothermally and non-isothermally [21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Heat capacities and thermodynamic properties of Ni9(btz)12(DMA)6(NO3)6

Zhou

Sun

Cao

et al. 2012

The low-temperature molar heat capacity of crystalline Ni 9 (btz) 12 (DMA) 6 (NO 3 ) 6 (1) (btz = benzotriazolate; DMA = N,N 0 -dimethylacetamide) was measured by temperature-modulated differential scanning calorimetry for the first time. The thermodynamic parameters such as entropy and enthalpy relative to reference temperature 298.15 K were obtained based on the above molar heat capacity data. The compound was synthesized by solvothermal method and characterized by powder X-ray diffraction and FT-IR spectra. Moreover, the thermal stability and the decomposition mechanism of Ni 9 (btz) 12 (DMA) 6 (NO 3 ) 6 were investigated by thermogravimetry (TG) analysis under air atmosphere from 300 to 873 K. The experimental results through TG measurement demonstrate that the compound has a two-stage mass loss in air flow.