• Applied Microscopy
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• v.47 no.3
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• pp.110-120
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• 2017

Non-isothermal thermogravimetry (TG) measurements on melt-quenched $Bi_xSe_{100-x}$ specimens (x=0, 2.5, 7.5 at%) were made at a heating rate ${\beta}=10^{\circ}C/min$ in the range $T=35^{\circ}C{\sim}950^{\circ}C$. The as-measured TG curves confirm that $Bi_xSe_{100-x}$ samples were thermally stable with minor loss at $T{\leq}400^{\circ}C$ and mass loss starts to decrease up to $600^{\circ}C$, beyond which trivial mass loss was observed. These TG curves were used to estimate molar (Se/Bi)-ratios of $Bi_xSe_{100-x}$ samples, which were not in accordance with initial composition. Shaping features of conversion curves ${\alpha}(T)-T$ of $Bi_xSe_{100-x}$ samples combined with a reliable flow chart were used to reduce kinetic mechanisms that would have caused their thermal mass loss to few nth-order reaction models of the form $f[{\alpha}(T)]{\propto}[1-{\alpha}(T)]^n$ (n=1/2, 2/3, and 1). The constructed ${\alpha}(T)-T$ and $(d{\alpha}(T)/dT)-T$ curves were analyzed using Coats-Redfern (CR) and Achar-Brindley-Sharp (ABS) kinetic formulas on basis of these model functions, but the linearity of attained plots were good in a limited ${\alpha}(T)-region$. The applicability of CR and ABS methods, with model function of kinetic reaction mechanism R0 (n=0), was notable as they gave best linear fits over much broader ${\alpha}(T)-range$.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.21 no.3
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• pp.107-113
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• 2015

This work focused on the study of thermal properties and kinetic behavior of LDPE-nanoclay composite films. The effect of nanoclay content (0.5, 1, 3, and 5 wt%) on thermal stability and crystallization characteristics of the nanocomposites were investigated by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The results from endothermic curve showed that the nanoclay played an important role in the crystallization of nanocomposites by acting as nucleating agent. From exothermic curve, there was a crystallization temperature shift which was attributed to crystallization process induced by nanoclay. The TGA results showed that the addition of nanoclay significantly increased the thermal stability of LDPE matrix, which was likely due to the characteristic of layered silicates/clays dispersed in LDPE matrix as well as the formation of multilayered carbonaceous-silicate char. A well-known Coats-Redfern method was used to evaluate the decomposition activation energy of nanocomposite. It was demonstrated that introducing of nanoclay to LDPE matrix escalated the activation energy of nanocomposite decomposition resulting in thermal stability improvement.

• Journal of the Korean Chemical Society
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• v.55 no.3
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• pp.341-345
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• 2011

The Schiff base cobalt(II) complex, bis[4-chloro-2-((E)-(isopropylimino) methyl) phenol]cobalt(II), has been prepared and characterized by single-crystal X-ray diffraction analyses. The phenomenological, kinetic and mechanistic aspects of the cobalt (II) complex have been studied by TG/DTG techniques. On the basis of the experimental data, the kinetic parameters such as activation energy, pre-exponential factor and entropy of activation were computed, and then the most probable mechanism function was estimated as $g({\alpha})={\alpha}^2$ 2. Hence the rate controlling process at all stages of decomposition is onedimensional diffusion (Parabolic model).

• Journal of the Korean Chemical Society
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• v.58 no.2
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• pp.169-178
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• 2014

A new series of metal complexes of V(IV), Pd(II), Pt(IV), Ce(IV) and U(VI) with 3-[(3-chlorophenyl)-hydrazono]-pentane-2,4-dione (Cphpd) were synthesized and characterized by elemental analysis, molar conductivity, magnetic moment measurements, UV-vis, FT-IR and $^1H$ NMR as well as TG-DTG techniques. The data indicated that the Cphpd acts as a bidentate ligand through the hydrazono nitrogen and one keto oxygen. The kinetic parameters have been evaluated by using Coats Redfern (CR) and Horowitz-Metzeger (HM) methods. The thermodynamic data reflected the thermal stability for all complexes. The calculated bond length and the bond stretching force constant, F(U=O), values for $UO_2$ bond are $0.775{\AA}$ and $286.95Nm^{-1}$. The bond lengths, bond angles, dipole moment and the lowest energy model structure of the complexes have been determined with DFT calculations. The antimicrobial activity of the synthesized ligand and its complexes were screened.