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Kissinger Method (kissinger + method)
Selected AbstractsThermal, phase transition and spectral studies in erythromycin pseudopolymorphs: dihydrate and acetone solvateCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2006Zhanzhong Wang Abstract The thermal, phase transition and spectral studies of erythromycin A dihydrate and acetone solvate were performed by Differential Scanning calorimetry (DSC), Thermo Gravimetry (TG-DTA), X-Ray Powder Diffraction (XRPD) and Fourier Transform Infra-Red (FTIR) spectrum. The non-thermal kinetic analysis of erythromycin A dihydrate was carried out by DSC at different heating rates in dynamic nitrogen atmosphere. The result showed that heating rate has substantial influence on the thermal behavior of erythromycin dihydrate. The Arrhenius parameters were estimated according to the Kissinger method. Corresponding to dehydration of dihydrate, melting of dehydrated dihydrate, phase transition from dehydrated dihydrate to anhydrate, and melting of anhydrate, the calculated activation energy were 39.60, 269.85, 261.23, and 582.16 kJmol,1, the pre-exponential factors were 3.46 × 103, 8.06 × 1032, 9.23 × 1030, and 7.29 × 1063 s,1, respectively. Ozawa method was used to compare activation energy values calculated by Kissinger method. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nonisothermal and isothermal crystallization kinetics of nylon-12JOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008Neil L. A. McFerran Abstract The isothermal and nonisothermal crystallization behavior of Nylon 12 was investigated using differential scanning calorimetry (DSC). An Avrami analysis was used to study the isothermal crystallization kinetics of Nylon 12, the Avrami exponent (n) determined and its relevance to crystal growth discussed and an activation energy for the process evaluated using an Arrhenius type expression. The Lauritzen and Hoffman analysis was used to examine the spherulitic growth process of the primary crystallization stage of Nylon 12. The surface-free energy and work of chain folding were calculated using a procedure reported by Hoffmann and the work of chain folding per molecular fold (,) and chain stiffness of Nylon 12 (q) was calculated and compared to values reported for Nylons 6,6 and 11. The Jeziorny modification of the Avrami analysis, Cazé and Chuah average Avrami parameter methods and Ozawa equation were used in an attempt to model the nonisothermal crystallization kinetics of Nylon 12. A combined Avrami and Ozawa treatment, described by Liu, was used to more accurately model the nonisothermal crystallization kinetics of Nylon 12. The activation energy for nonisothermal crystallization processes was determined using the Kissinger method for Nylon 12 and compared with values reported previously for Nylon 6,6 and Nylon 11. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Nucleation and Crystallization of a Lead Halide Phosphate Glass by Differential Thermal AnalysisJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2002Hongsheng Zhao The nucleation and crystallization mechanisms of a lead halide phosphate glass [40P2O5·30PbBr2·30PbF2 (mol%)] were investigated by differential thermal analysis (DTA) and X-ray diffraction analysis. There were two crystalline phases in the crystallized samples: the major phase was PbP2O4, and the minor phase was PbP2O6. The average activation energy for crystallization, E, for two different particle sizes of this glass was determined to be 119 ± 4 kJ/mol by the Kissinger method and 124 ± 4 kJ/mol by the Augis,Bennett method. The Avrami constants were determined to be 1.6 and 2.5 for particle sizes of 203 and 1040 ,m, respectively, by the Ozawa equation, and 1.7 and 2.4 for particle sizes of 203 and 1040 ,m, respectively, by the Augis,Bennett equation. The decrease in the crystallization peak height in the DTA curve with increasing particle size suggested that the particles crystallize primarily by surface crystallization. A nucleation-rate type curve was determined by plotting either the reciprocal of the temperature corresponding to the crystallization peak maximum, 1/Tp, or the height of the crystallization peak, (,T)p, as a function of nucleation temperature, Tn. The temperature where nucleation can occur for this glass ranges from 360°,450°C and the maximum nucleation rate is at 420°± 10°C. [source] Thermal behavior and flame retardancy of flexible poly(vinyl chloride) treated with zinc hydroxystannate and zinc stannateJOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 1 2008Weihong Wu The flame-retardant and smoke-suppressant properties of inorganic tin compounds such as zinc hydroxystannate (ZHS) and zinc stannate (ZS) were studied in comparison with those of alumina trihydrate and magnesium hydroxide through the limiting oxygen index test and a smoke density test. The thermal degradation in air of flexible poly(vinyl chloride) (PVC) treated with the above compounds was studied by thermal analysis from ambient temperature to 800°C. The activation energy was calculated by using the Vyazovkin model-free kinetic method and the Kissinger method. The results showed that tin compounds such as ZHS and ZS could be used as highly effective flame retardants for flexible PVC; these flame retardants enhanced the stability and the activation energy of the oxidation of the char. J. VINYL ADDIT. TECHNOL, 2008. © 2008 Society of Plastics Engineers [source] A Kinetic Study on the Thermal Degradation of Multi-Walled Carbon Nanotubes-Reinforced Poly(propylene) CompositesMACROMOLECULAR MATERIALS & ENGINEERING, Issue 4 2004Min-Kang Seo Abstract Summary: The influence of the multi-walled carbon nanotubes (MWNTs) content on the thermal degradation behavior of MWNTs-reinforced poly(propylene) (PP) composites was investigated by using non-isothermal thermogravimetric analysis (TGA). Kinetic parameters of degradation were evaluated by using the Flynn-Wall-Ozawa iso-conversional method and the pseudo first-order method. As a result, compared with pristine PP, MWNTs-PP nanocomposites have lower peak temperatures of degradation, narrower degradation temperature ranges and a higher amount of residual weight at the end of the degradation, which is likely to be a result of specific interactions between complimentary functional groups. The values of the reaction order of MWNTs-PP nanocomposites determined by the Kissinger method are close to 1 in the non-isothermal degradation process. There is a good correlation between the Ea in region II and the peak temperature of degradation for the composites. Activation energies for degradation of different contents of MWNTs-filled PP nanocomposites as a function of conversion. [source] Isothermal and nonisothermal crystallization kinetics of nylon 10 12POLYMER ENGINEERING & SCIENCE, Issue 9 2000Yongjin Li This article studied the crystallization behaviors of a newly industrialized polyamide, Nylon 10 12, under isothermal and nonisothermal conditions from the melt. A differential scanning calorimeter (DSC) was used to monitor the energetics of the crystallization process. During isothermal crystallization, relative crystallinity develops in accordance with the time dependence described by the Avrami equation with the exponent n=2.0. For nonisothermal studies, several different analysis methods were used to describe the crystallization process. The experimental results show that the Ozawa approach cannot adequately describe the nonisothermal crystallization kinetics. However, Avrami treatment for nonisothermal crystallization is able to describe the system very well. The calculated activation energy is 264.4 KJ/mol for isothermal crystallization by Arrhenius form and 235.5 KJ/mol for nonisothermal crystallization by Kissinger method. [source] Nonisothermal crystallization behavior of a luminescent conjugated polymer, poly(9,9-dihexylfluorene- alt -2,5-didodecyloxybenzene)POLYMER INTERNATIONAL, Issue 2 2007Gui-Zhong Yang Abstract The nonisothermal crystallization kinetics of poly(9,9-dihexylfluorene- alt -2,5-didodecyloxybenzene) (PF6OC12) from the melt were investigated using differential scanning calorimetry under different cooling rates. Several analysis methods were used to describe the nonisothermal crystallization behavior of PF6OC12. It was found that the modified Avrami method by Jeziorny was only valid for describing the early stage of crystallization but was not able to describe the later stage of PF6OC12 crystallization. Also, the Ozawa method failed to describe the nonisothermal crystallization behavior of PF6OC12. However, the method developed by combining the Avrami and Ozawa equations could successfully describe the nonisothermal crystallization kinetics of PF6OC12. According to the Kissinger method, the activation energy was determined to be 114.9 kJ mol,1 for the nonisothermal melt crystallization of PF6OC12. Copyright © 2006 Society of Chemical Industry [source] An Investigation on Thermal Decomposition of DNTF-CMDB PropellantsPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 6 2007Wei Zheng Abstract The thermal decomposition of DNTF-CMDB propellants was investigated by pressure differential scanning calorimetry (PDSC) and thermogravimetry (TG). The results show that there is only one decomposition peak on DSC curves, because the decomposition peak of DNTF cannot be separated from that of the NC/NG binder. The decomposition of DNTF can be obviously accelerated by the decomposition products of the NC/NG binder. The kinetic parameters of thermal decompositions for four DNTF-CMDB propellants at 6,MPa were obtained by the Kissinger method. It is found that the reaction rate decreases with increasing content of DNTF. [source] Synthesis, characterization, and properties of novel ladderlike phosphorus-containing polysilsesquioxanesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2003Chin-Lung Chiang Abstract Novel ladderlike polysilsesquioxanes that contain phosphorus were successfully synthesized by the sol,gel method. The polysilsesquioxanes were characterized by Fourier transform infrared spectroscopy, 29Si NMR, and X-ray diffraction. The characterizations demonstrated that the polymer possesses a typical ladderlike structure. The thermogravimetric and differential scanning calorimetric data revealed that the polysilsesquioxanes possess excellent thermal stability. A kinetic analysis of thermal degradation showed that the activation energy of thermal degradation is 187 kJ/mol, according to Kissinger's method. The activation energy of thermal degradation normally increases with conversion (from 171 to 309 kJ/mol) according to Ozawa's method. The average activation energy, calculated by Ozawa's method, was 209 kJ/mol. The scanning electron microscopic photograph and Si and P mappings of ladderlike polysilsesquioxanes showed that the particles were uniformly dispersed at the molecular level and that the sizes of the polysilsesquioxane particles were less than 100 nm. The ultraviolet,visible spectra of the ladderlike polysilsesquioxanes revealed no absorbance in the range of 400,800 nm. Ladderlike polysilsesquioxanes possess excellent optical transparency and excellent flame retardance. This transmittance may be used as a criterion for identifying the formation of a homogeneous phase. These polymers have great potential in waveguide applications. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1371,1379, 2003 [source] | ||||||||||