• Title, Summary, Keyword: Kissinger method

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Synthesis and Properties of Fe-Ni Nano-sized Powders using Metal Nitrates (금속질산염을 이용한 Fe-Ni 나노분말의 제조 및 특성)

  • Joo, Min-Hee;Oh, Sung-Tag
    • Journal of Korean Powder Metallurgy Institute
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    • v.16 no.3
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    • pp.191-195
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    • 2009
  • The calcination and hydrogen-reduction behavior of Fe- and Ni-nitrate have been investigated. $Fe_2O_3$/NiO composite powders were prepared by chemical solution mixing of Fe- and Ni-nitrate and calcination at $350^{\circ}C$ for 2 h. The calcined powders were hydrogen-reduced at $350^{\circ}C$ for 30 min. The calcination and hydrogen-reduction behavior of Fe- and Ni-nitrate were analyzed by TG in air and hydrogen atmosphere, respectively. TG and XRD analysis for hydrogen-reduced powders revealed that the $Fe_2O_3$/NiO phase transformed to $FeNi_3$ phase at the temperature of $350^{\circ}$. The activation energy for the hydrogen reduction, evaluated by Kissinger method, was measured as 83.0 kJ/mol.

Thermal Characteristics of Polypropylene in Combustion Reaction Using TGA (TGA를 이용한 폴리프로필렌의 연소반응에서의 열적 특성 연구)

  • Kang, Yun-Jin;Seo, Su-Eun;Seo, Gyu-Suk;Kang, Kyung-Sik
    • Journal of the Korea Safety Management and Science
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    • v.10 no.4
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    • pp.111-120
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    • 2008
  • The combustion reaction of polypropylene was investigated using a thermogravimetric technique under an air atmosphere condition at several heating rates from 10 to $50^{\circ}C/min$. To obtain information on the kinetic parameters, the dynamic thermogravimetric analysis curve and its derivative were analyzed by a variety of analytical methods such as Kissinger, Friedman, Freeman-Carroll, Chatterjee-Conrad, Ozawa and Coats-Redfern methods. The comparative works for the kinetic results obtained from various methods should be performed to determine the kinetic parameters, because there are tremendous differences in the calculated kinetic parameters depending upon the mathematical method taken in the analysis.

Studies on Cure Behavior, Thermal Stability, and Rheological properties of Tetrafunctional Epoxy/Biodegradable MAP Blends (4관능성 에폭시/생분해성 MAP 블렌드의 열적 특성 경화거동 및 유변학적 특성에 관한 연구)

  • 박수진;신유식;김봉섭;박병기
    • Textile Science and Engineering
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    • v.38 no.4
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    • pp.164-173
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    • 2001
  • The effect of biodegradable modified aliphatic polyester (MAP) on neat tetrafunctional epoxy (4EP) was investigated in terms of cure kinetics, thermal stabilities, and rheological properties. The 4,4'-diamino diphenyl methane (DDM) was used as a curing agent for the blend system and the content of 4EP/MAP was varied with the in the 100:0, 90:10, 80:20, 70:30, and 60:40 wt%. As a result, the cure activiation energies ($E_{a}$) for the cure kinetics obtained by dynamic DSC method using Kissinger equation, were increased in 10 and 20 wt% of MAP compared with neat 4EP, due to the increasing intermolecular interaction between 4EP and MAP. And the decomposition activation energies ($E_{t}$) for thermal stability derived fromthe integral method of Horowitz-Metzger equation, were increased within the 10∼30 wt% composition range of MAP, resulting from increased crosslinking density in the blend system. The cross-linking activation energies ($E_{c}$) for rheological properties determined from the Arrhenius equation based on gel time and curing temperature, exhibited similar behavior to those of integral method which could be explained by the miscibility between 4EP and MAP.

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A Consideration on Thermal Stability of the PVAc Latex Adhesive (PVAc 라텍스 접착제의 열적 안정성에 대한 고찰)

  • 권재범;이내우;설수덕
    • Journal of the Korean Society of Safety
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    • v.18 no.3
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    • pp.81-87
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    • 2003
  • Latex polymers are widely used for adhesive, binder, paint etc. Especially the PVAc(Polyvinyl acetate) latex which manufactured by vinyl acetate and vinyl alcohol as protective colloid is a useful environmentally friendly adhesive. To increase useful property of PVAc latex, this study was carried out for checking thermal characteristics and physical condition of PVAc latex by DSC, FT-IR, Pyrolyzer GC-MS. The activation energies of thermal decomposition for 40, 48, 56, 64% solid content of PVAc latex were found as 28.1-36.0kcal/mol by Kissinger's method and 17.2-22.0kcal/mol by DSC method. Actually, reasonable solid content could be consiered as 56% because of activation energy and adhesive characteristics. According to the effect of protective colloid for 4, 10, 15, 20wt%, the activation energy shows same tendency to both method and in case of l5wt% has been found as the highest activation energy. The mechanism of thermal decomposition was mainly estimated by main chain scission, not by side group on FT-IR analysis. Main component of Pyrolzer GC-MS result were consisted of $CH_3COOH$, $CH_3$, $H_2O$ and light gases(CO, $CO_2$, $CH_4$ etc).

Analysis of Thermal Degradation Process if Commercial Rubber for Environmentally Benign Process (범용고무의 환경친화적 처리를 위한 열분해 공정 해석)

  • 김형진;정수경
    • Journal of environmental and Sanitary engineering
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    • v.15 no.4
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    • pp.123-133
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    • 2000
  • The kinetic analysis was carried out for commercial rubbers such as NR, IR, BR, SBR 1500, and SBR 1700. Kinetic analysis for the commercial rubbers was performed using the thermogravimetric method, with which the activation energies of NR obtained by Kissinger, Friedman, and Ozawa's method were 195.0, 198.3 and 186.3kJ/mol, whereas that of SBR 1500 were 246.4, 247.5 and 254.8kJ/mol, respectively. It was shown that the yield of pyrolytic oil was generally increased with final temperature increasing, yet slightly decreased or increased over $700^{\circ}C$. Considering the effect of heating rate, it was found that the yield of pyrolytic oil was not consistent for each sample. The number average molecular weight of SBR 1500 was in the range of 740~2486. The calorific value of SBR 1500 was 39~40kJ/g, which were made comparative study of the conventional fuel such as kerosene, diesel, light fuel, and heavy fuel. Therefore it was essential that the selection of the suitable kinetic model and the mathematical solution because of the difference in parameters obtained from each method. It was proposed that the range of $600~700^{\circ}C$ in final temperature and high heating rate due to short run time. It was suggested that the pyrolytic oil be available to use to the fuel.

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Thermal Degradation Kinetics of Antimicrobial Agent, Poly(hexamethylene guanidine) Phosphate

  • Lee, Sang-Mook;Jin, Byung-Suk;Lee, Jae-Wook
    • Macromolecular research
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    • v.14 no.5
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    • pp.491-498
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    • 2006
  • The thermal degradation of poly(hexamethylene guanidine) phosphate (PHMG) was studied by dynamic thermogravimetric analysis (TGA) and pyrolysis-GC/MS (p-GC). Thermal degradation of PHMG occurs in three different processes, such as dephosphorylation, sublimation/vaporization of amine compounds and decomposition/ recombination of hydrocarbon residues. The kinetic parameters of each stage were calculated from the Kissinger, Friedman and Flynn-Wall-Ozawa methods. The Chang method was also used for comparison study. To investigate the degradation mechanisms of the three different stages, the Coats-Redfern and the Phadnis-Deshpande methods were employed. The probable degradation mechanism for the first stage was a nucleation and growth mechanism, $A_n$ type. However, a power law and a diffusion mechanism, $D_n$ type, were operated for the second degradation stage, whereas a nucleation and growth mechanism, $A_n$ type, were operated again for the third degradation stage of PHMG. The theoretical weight loss against temperature curves, calculated by the estimated kinetic parameters, well fit the experimental data, thereby confirming the validity of the analysis method used in this work. The life-time predicted from the kinetic equation is a valuable guide for the thermal processing of PHMG.

Kinetic Studies of Pyrolysis and Char-$CO_2$ Gasification on Low Rank Coals (저급탄의 열분해 및 촤-$CO_2$ 가스화 반응의 속도론적 연구)

  • Kang, Suk-Hwan;Ryu, Jae-Hong;Park, Soo-Nam;Byun, Yong-Soo;Seo, Seok-Jung;Yun, Yong-Seung;Lee, Jin-Wook;Kim, Yong-Jeon;Kim, Joo-Hoe;Park, Sam-Ryong
    • Korean Chemical Engineering Research
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    • v.49 no.1
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    • pp.114-119
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    • 2011
  • Thermogravimetric analysis(TGA) was carried out for pyrolysis and char-$CO_2$ gasification of low rank Indonesian ABK coal and China lignite. The pyrolysis rate was successfully described by a two-step model adopting the modified Kissinger method. The shrinking core model, when applied to char-$CO_2$ gasification gave initial activation energy of 189.1 kJ/mol and 260.5 kJ/mol for the ABK coal and China lignite, respectively. Thus, the char-$CO_2$ gasification has been successfully simulated by the shrinking core model. In particular, the activation energy of char-$CO_2$ gasification calculated in this work is similar to the results on the anthracite coal, but considerable difference exists when other models or coal types are used.

Slow Cook-Off Test and Evaluation for HTPE Insensitive Propellants (HTPE 둔감추진제 완속가열 시험평가)

  • Yoo, Ji-Chang;Kim, Chang-Kee;Kim, Jun-Hyung;Lee, Do-Hyung;Min, Byung-Sun
    • Journal of the Korean Society of Propulsion Engineers
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    • v.14 no.6
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    • pp.31-37
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    • 2010
  • This study was carried out to investigate the thermal decomposition and execute EIDS slow cook-off test for the propellant ingredients and 2 kinds of HTPE propellants. The thermal analysis of the propellant ingredients used in this study showed that the thermal stability of these materials decreases in the following order : AP > HTPE > AN > BuNENA. In addition, propellant HTPE 002 containing AN showed that an endothermic process at around $125^{\circ}C$ corresponding to the solid phase change(II$\rightarrow$I) of AN was followed by the exothermic process of BuNENA/AN mixture up to $200^{\circ}C$. In EIDS slow cook-off tests, HTPE 001 and HTPE 002 reacted at around $250^{\circ}C$ and $152^{\circ}C$ respectively, and both of them showed sudden temperature increase curves at $115^{\circ}C$. The critical temperatures, $T_c$, of thermal explosion for the propellants HTPE 001 and HTPE 002, were obtained from both the non-isothermal curves at various heating rates and Semenov's thermal explosion theory. Kissinger's method that was used to calculate $T_c$ was also employed to obtain the activation energies for thermal decompositions.

Study on the Non-isothermal Crystallization Kinetics of Branched Polypropylene (분지형 폴리프로필렌의 비등온결정화 거동 연구)

  • Yoon, Kyung-Hwa;Shin, Dong-Yup;Kim, Youn-Cheol
    • Polymer Korea
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    • v.36 no.2
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    • pp.245-250
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    • 2012
  • Branched polypropylenes (PP) with long chain branch were prepared by solid state reaction with three different branching agent of 0.3 wt% content. The chemical structures, non-isothermal crystallization behavior and complex viscosity of the branched PP were investigated by FTIR, DSC, optical microscope, and dynamic rheological measurement. The chemical structure of the branched PP was confirmed by the existence of =C-H stretching peak of the branching agent at 3100 $cm^{-1}$. There was no distinct change in melting temperature in case of PP-D-0-3 and PP-F-0-3, but PP-H-0-3 indicated a decrease in melting temperature. The decrease in melting temperature was interpreted by the fact that the degradation reaction of PP was more dominant than branched reaction, and confirmed by a decrease in complex viscosity. The non-isothermal crystallization behavior of the branched PP was analyzed using by Avrami equation. The Avrami exponent of PP was 3, and the values of the branched PP with DVB and FS were below 3. The activation energy of PP calculated by Kissinger method was 25 kJ/mol, and there were no big difference in activation energies of the branched PPs compared to PP.

Determination of reaction kinetics during vitrification of radioactive liquid waste for different types of base glass

  • Suneel, G.;Rajasekaran, S.;Selvakumar, J.;Kaushik, Chetan P.;Gayen, J.K.;Ravi, K.V.
    • Nuclear Engineering and Technology
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    • v.51 no.3
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    • pp.746-754
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    • 2019
  • Vitrification of radioactive liquid waste (RLW) provides a feasible solution for isolating radionuclides from the biosphere for an extended period. In vitrification, base glass and radioactive waste are added simultaneously into the melter. Determination of heat and mass transfer rates is necessary for rational design and sizing of melter. For obtaining an assured product quality, knowledge of reaction kinetics associated with the thermal decomposition of waste constituents is essential. In this study Thermogravimetry (TG) - Differential Thermogravimetry (DTG) of eight kinds of nitrates and two oxides, which are major components of RLW, is investigated in the temperature range of 298-1273 K in the presence of base glasses of five component (5C) and seven component (7C). Studies on thermal behavior of constituents in RLW were carried out at heating rates ranging from 10 to $40\;K\;min^{-1}$ using TG - DTG. Thermal behavior and related kinetic parameters of waste constituents, in the presence of 5C and 7C base glass compositions were also investigated. The activation energy, pre-exponential factor and order of the reaction for the thermal decomposition of 24% waste oxide loaded glasses were estimated using Kissinger method.