• 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.

• Fibers and Polymers
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• v.4 no.4
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• pp.195-198
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• 2003

Epoxidized polybutadiene (EPB) was prepared by polybutadiene (PB) with m-chloroperbenzoic acid (MCPBA) in homogeneous solution. EPB was blended with poly(3-hydroxybutyrate) (PHB) up to 30 wt% by solution-precipitation procedure. The thermal decomposition of PHB/EPB blends was studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and differential thermal analysis (DTA). The thermograms of PHB/EPB blends contained a two-step degradation process, while that of pure PHB sample exhibited only one-step degradation process. This degradation behavior of PHB/EPB blends, which have a higher thermal stability as measured by maximum decomposition temperature and residual weight, is probably due to crosslinking reactions of the epoxide groups in the EPB component with the carboxyl chain ends of PHB fragments during the degradation process, and the occurrence of such reactions can be assigned to the exothermic peaks in their DTA thermograms.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.113-122
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• 2010

A two-dimensional thermal response and ablation analysis code for predicting charring material ablation and shape change on solid rocket nozzle is presented. For closing the problem of thermal analysis, Arrhenius' equation and Zvyagin's ablation model are used. The moving boundary problem are solved by remeshing-rezoning method. For simulation of complicated thermal protection systems, this method is integrated with a three-dimensional finite-element thermal and structure analysis code through continuity of temperature and heat flux.

• Journal of the Korean Chemical Society
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• v.7 no.1
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• pp.1-5
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• 1963

The thermal decomposition process of ammonium paratungstate $5(NH_4)_2O{\cdot}12WO_3{\cdot}5H_2O$ was analysed by the methods of thermogravimetric analysis, differential thermal analysis, quantitative analysis of the ammonia which is released during heating and X-ray powder diffraction in air and in vacuo. There are several endothermic peaks which indicate release of ammonia and exothermic peaks which indicate crystal growth and oxidation of decomposed prodects in air. After water is driven off the ammonia is released at intervals corresponding to the endothermic peaks. The highest temperature at which ammonia is released is about $420^{\circ}C$ in air and $480^{\circ}C$ in vacuo. In air the crystal structure of paratungstate is conserved up to a temperature of $300^{\circ}C$ at which the remaining ammonia is about 4 mols. At $320^{\circ}C$ the remaining ammonia becomes less than 2 mols and the paratungstate structure changes into the amorphous state. After that ${\gamma}$ oxide is produced and is oxidized to ${\alpha}$ oxide in the temperature range of 400-$500^{\circ}C$ in air. In vacuo however the endothermic peaks and structural changes occur at lower temperatures and the structure of ${\gamma}$ oxide is conserved up to temperatures higher than $500^{\circ}C$.

• Journal of Photoscience
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• v.10 no.2
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• pp.209-214
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• 2003

A series of coupled-hemicyanine dyes with alkylene spacer were successfully synthesized by a reaction of coupled aldehydes with corresponding salts, respectively. These coupled dyes had more excellent thermal properties (high decomposition temperature, stiff decomposition behavior) and higher molar absorption properties than an uncoupled dye. The coupled dyes with perchlorate anions showed the strongest exothermic decomposition while those with hexafluorophosphorate anions showed endothermic decomposition. As the coupling length (n=3, 4, 5, 6) increased, thermal properties decreased and dyes with even spacer was more thermally stable than dyes with odd spacer. Among several coupled dyes, C4-NP-ClO4 and C4-Cl-ClO4 exhibited the best recording properties with the lowest jitter value of 7.5∼9.5% in authoring disc.

• Journal of the Korean Institute of Gas
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• v.26 no.5
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• pp.41-48
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• 2022

2-Chloro-N-(Cyano-2-thienyl methyl) acetamide (CCTA) is an intermediate used for synthesizing pesticides. It is stable at room temperature and pressure but can be decomposed when heat is accumulated. In this study, the decomposition characteristics were evaluated by measuring the weight change according to temperature using a Thermogravimetry analyzer(TGA), and the thermal decomposition characteristics were evaluated using Differential Scanning Calorimeter(DSC). The exothermic decomposition reaction occurred rapidly at about 91 ℃, and the activation energy determined by using Kissinger method, Kissinger-Akahira-Sunose(KAS) method, and Flynn-Wall-Ozawa(FWO) method were 162 kJ/mol, 149 kJ/mol and 139 kJ/mol, respectively. T_D24, the temperature at which the maximum heating rate is reached within 24 hours, was evaluated as 52~55 ℃ using the estimated activation energy.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.4
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• pp.293-302
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• 1998

This study was performed to investigate the behavior of chlorobenzenes (CIBZS) and chlorophenols (CIPhs) in a thermally treated MSWI fly ash. The experiment was carried out in a fixed bed reactor at the temperature range of 300~$600^{\circ}C$. Reaction time range was between 30 and 120 minutes, and NB and 02 gases were used as carrier gas. The decomposition rate of CIBZS was more affected by reaction time than by the reaction temperature. The decomposition rate of CIPhs was affected by both parameters. Decomposition rate of CIBZS and CIPhs reached 80.4% and 96.6% at $600^{\circ}C$, 120 min, respectively. Considering the effect of O2 content, decomposition rate of CIBZS and CIPhs was the highest at 10% of O2 content. Declorination and decomposition reactions Pere investigated by analyzing homologue distribution. Higher chlorinated CIBZS and CIPhs homologue decreased but lower chlorinated compounds increased with the increase of temperature. Effect of O2 on the homologue distribution of these compounds was not clear in the range of our experiment conditions.

• Elastomers and Composites
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• v.50 no.4
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• pp.297-303
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• 2015

Ammonium polyphosphate-polyurethane foam composite (APP-PUF) was prepared from poly(adipate)diol/ammonium polyphosphate composite (f = 2), polyether polyol (f = 4.6), and PMDI (f = 2.5). As a blowing agent, $H_2O$ was used at various concentrations. The thermal decomposition behavior, morphology, closed-cell content, and density of APP-PUF were characterized. At the $H_2O$ concentrations lower than 3.5 php, the cell size of pure polyurethane foams (PUF) and APP-PUFs were close each other. As the $H_2O$ concentration became greater than 5.0 php, the cell size of the PUFs greatly increased compared to that of APP-PUFs. Addition of 1.5~1.9 wt% ammonium polyphosphate to the PUFs greatly enhanced the thermal stability of the PUFs, so 50 wt% residual temperature of APP-PUFs increased to $380{\sim}488^{\circ}C$, which were $30{\sim}70^{\circ}C$ higher than those of the PUFs. Thermal stability of the PUFs and APP-PUFs increased with $H_2O$ content and then decreased once $H_2O$ content exceeded 5 php.

• Elastomers and Composites
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• v.40 no.4
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• pp.266-271
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• 2005

In this work, the thermal stability factors, such as the thermal decomposition temperature, decomposition activation energy ($E_d$), and char yield, were measured to investigate the effect of silicone rubber (SR) content on the thermal stabilities of EPDM/SR blends. As a result, the thermal decomposition curve of EPDM/SR blends was similar to the neat EPDM rubber at 10 wt% SR and the thermal decomposition temperature increased above this content. The $E_d$ value of EPDM rubber initially decreased and then was constant above 20 wt% weight losses. The $E_d$ of EPDM/SR blends was higher than that of the neat EPDM rubber and then decreased with increasing the weight loss when the SR content was in the range of 10-20 wt%. Whereas the $E_d$ of the blends was lower than that of the EPDM rubber and then decreased with increasing the weight loss when 30 wt% SR was added. The char yield at $800^{\circ}C$ increased with increasing the SR content, because the decomposition of silane groups in the backbone was capable of forming a silane-rich residue after the initial stage of thermal degradation, which finally prevents further heat transfer and diffusion in the blends.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.2
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• pp.104-110
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• 2019

The thermal decomposition characteristics of boron-potassium nitrate ($BKNO_3$) were investigated by non-isothermal thermal gravimetric analysis (TGA). Two steps of mass loss were observed in the temperature range between room temperature and $600^{\circ}C$. Kinetic parameters of the thermal decompositions were evaluated from the measured TGA curves using the AKTS Thermokinetics Software. For the first step of mass loss ($220-360^{\circ}C$) corresponding to the thermal decomposition process of the binder (Laminac/Lupersol), the activation energy is in the range of approximately 120-270 kJ/mol when evaluated by Friedman's iso-conversional method, while the value of activation energy varies in the range of approximately 150-400 kJ/mol during the second step process ($360-550^{\circ}C$).