• Title, Summary, Keyword: Differential Scanning Calorimetry Analysis

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Kinetic Measurements on Elastomer by Differential Scanning Calorimetry (Differential Scanning Calorimetry에 의(依)한 탄성체(彈性體)의 속도론적(速度論的) 연구(硏究))

  • Choi, Sei-Young
    • Elastomers and Composites
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    • v.22 no.4
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    • pp.333-339
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    • 1987
  • A modern kinetic evaluation method for nonisothermal reactions measured with Differential Scanning Calorimetry(DSC) is presented. It is based on multiple linear regression analysis using a number of curve points in a selectable range of conversion. The obtained kinetic data are the basis to compute a reaction process under any condition e.g. isothermal or adiabatic. The DSC measurements was performed on a Mettler TA3000 SYSTEM with the built in evaluation software. Mainly the following reactions are discussed: vulcanization of natural rubber compounds containing vulcanizing accelerators. The purpose of this work is to analyse the vulcanization kinetics of typical NR vulcanization systems using DSC. These systems were chosen because they are typically reactive elastomer and are commercially important.

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An Experimental Study on Measurement of the Reaction Order of a Liquid Fuel with Various Components (혼합 액체연료의 화학반응차수 계측에 관한 실험적 연구)

  • Choi, Hyo-Hyun;Lim, Jun-Seok;Kim, Chul-Jin;Sohn, Chae-Hoon
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.421-424
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    • 2011
  • Thermal Analyses are conducted to measure various factors of a liquid fuel required for numerical analysis. Thermal Analyses are divided into two different methods of TGA (Thermo Gravimetric Analysis) and DSC (Differential Scanning Calorimetry). Non-isothermal experimental results are analyzed using by TGA. The results are filtered by a Freeman Carroll method. At the same time, chemical parameters of unknown liquid fuel, activation temperature and reaction order are measured to 6128.2 K and 1.4, respectively. Furthermore, the parameters can be obtained by various mathematical methods. It is found that tha parameters depend on the processing method.

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Study on the thermal Property and Aging Prediction for Pressable Plastic Bonded Explosives through ARC(Heat-Wait-Search method) & isothermal conditions (ARC(Heat-Wait-Search method)와 isothermal 조건을 이용한 압축형 복합화약의 열적 특성 및 노화 예측 연구)

  • Lee, Sojung;Kim, Jinseuk;Kim, Seunghee;Kwon, Kuktae;Chu, Chorong;Jeon, Yeongjin
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.172-178
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    • 2017
  • Thermal property is one of the important characteristic in the field of energetic materials. As the energy material is released during decomposition, DSC(Differential Scanning Calorimetry) is frequently used for the thermal analysis. In case of the dynamic DSC measurements, thermal dynamic change like melting is prevented from the thermal property measurements. And due to the predicting kg scale, the conditions of the heat exchange with the environment significantly is changed. In this study, As the method to resolve the problem, we predict the thermal aging property using the AKTS thermokinetic program from DSC measurements which performed isothermal method. Predicting the thermal aging properties from ARC(Accelerating Rate Calorimetry) measurement, we compare two results.

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Transition State Characterization of the Low- to Physiological-Temperature Nondenaturational Conformational Change in Bovine Adenosine Deaminase by Slow Scan Rate Differential Scanning Calorimetry

  • Bodnar, Melissa A.;Britt, B. Mark
    • BMB Reports
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    • v.39 no.2
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    • pp.167-170
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    • 2006
  • Bovine adenosine deaminase undergoes a nondenaturational conformational change at $29^{\circ}C$ upon heating which is characterized by a large increase in heat capacity. We have determined the transition state thermodynamics of the conformational change using a novel application of differential scanning calorimetry (DSC) which employs very slow scan rates. DSC scans at the conventional, and arbitrary, scan rate of $1^{\circ}C/min$ show no evidence of the transition. Scan rates from 0.030 to $0.20^{\circ}C/min$ reveal the transition indicating it is under kinetic control. The transition temperature $T_t$ and the transition temperature interval ${\Delta}T$ increase with scan rate. A first order rate constant $k_1$ is calculated at each $T_t$ from $k_1\;=\;r_{scan}/{\Delta}T$, where $r_{scan}$ is the scan rate, and an Arrhenius plot is constructed. Standard transition state analysis reveals an activation free energy ${\Delta}G^{\neq}$ of 88.1 kJ/mole and suggests that the conformational change has an unfolding quality that appears to be on the direct path to the physiological-temperature conformer.

The Thermal Stability Analysis of Fumes and Mists During the Drying Process of a PCB (PCB 건조공정의 흄과 미스트에 대한 열안정성 분석)

  • Chu, Chang Yeop;Lee, Jung Suk;Baek, Jong Bae
    • Journal of the Korean Society of Safety
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    • v.34 no.4
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    • pp.32-40
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    • 2019
  • During the manufacturing process of a printed circuit board(PCB), fumes and mists are generated as the ink dries on the PCB surface. The generated fumes and mists are deposited in the dryer wall and the exhaust duct. Deposited fumes and mists may present a fire hazard if the dryer temperature control system fails. In this study, the thermal stability of the fumes and mists deposited in the dryer and ducts has been analyzed by experimental methods such as thermo gravimetric analysis (TGA), differential scanning calorimetry (DSC), auto ignition temperature (AIT), and multiple mode calorimetry(MMC). According to the experimental analyses, experimental samples are likely to generate gas at the temperature ($180{\sim}240^{\circ}C$) that deviates from the normal operating temperature ($150{\sim}156^{\circ}C$). It has been shown that the thermal stability is degraded when the temperature is deviated from the normal operating temperature. In the end, engineering and management safety measures of accidental prevention have been suggested.

Study on the Thermal Property and Aging Prediction for Pressable Plastic Bonded Explosives through ARC(Heat-wait-search method) & Isothermal Conditions (ARC(Heat-wait-search method)와 Isothermal 조건을 이용한 압축형 복합화약의 열적 특성 및 노화 예측 연구)

  • Lee, Sojung;Kim, Seunghee;Kwon, Kuktae;Jeon, Yeongjin
    • Journal of the Korean Society of Propulsion Engineers
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    • v.22 no.4
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    • pp.55-60
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    • 2018
  • The thermal property is one of the most important characteristics in the field of energetic materials. Because energy materials release decomposition heat, differential scanning calorimetry (DSC) is frequently used for thermal analysis. However, thermodynamic events, such as melting can interfere with DSC kinetic analysis. In this study, we use isothermal mode for DSC measurement to avoid thermodynamic issues. We also merge accelerating rate calorimetry(ARC) data with DSC data to obtain a robust prediction results for small scale samples and for large scale samples as well. For the thermal property prediction, advanced kinetics and technology solutions(AKTS) programs are used.

Kinetics analysis of energetic material using isothermal DSC (등온 DSC를 이용한 고에너지 물질의 정밀 반응 모델 기법 개발)

  • Kim, Yoocheon;Park, Jungsu;Kwon, Kuktae;Yoh, Jai-ick
    • 한국연소학회:학술대회논문집
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    • pp.219-222
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    • 2015
  • The kinetic analysis of energetic materials using Differential Scanning Calorimetry (DSC) is proposed. Friedman Isoconversional method is applied to DSC experiment data and AKTS software is used for analysis. The frequency factor and activation energy are extracted as a function of product mass fraction. The extracted kinetic scheme does not assume multiple chemical steps to describe the response of energetic materials; instead, multiple set of Arrhenius factors are used in describing a single global step. The proposed kinetic scheme has considerable advantage over the standard method based on One-Dimenaionl Time to Explosion (ODTX). Reaction rate and product mass fraction simulation are conducted to validate extracted kinetic scheme. Also a slow cook-off simulation is implemented for validating the applicability of the extracted kinetics scheme to a practical thermal experiment.

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Characterization of energetic meterials using thermal calorimetry (등전환 방법을 이용한 고에너지 물질의 노화 효과 예측)

  • Kim, Yoocheon;Oh, Juyoung;Ambekar, Aniruda;Yoh, Jai-ick
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.547-553
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    • 2017
  • Thermal analysis of three energetic materials used in pyroelectric device was performed using Differential Scanning Calorimetry (DSC). The theoretical method for extracting the reaction rate equation of energetic materials using DSC experimental data is proposed and the reaction rate extraction is performed. The results of the DSC were analyzed by the conversion method such as Friedman. Activation energy and frequency factor according to mass fraction were extracted to complete the reaction rate equation. The extracted reaction rate equation has a form that represents the entire chemical reaction process, not the assumption that the chemical reaction process of the high energy material is a main step in several stages. It has considerable advantages in terms of theoretical and accuracy as compared with the chemical reaction rate form extracted through conventional thermal analysis experiments. Using the derived reaction rate equation, we predicted the performance change of three energetic materials operating on actual storage condition over 20 years.

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Crystal Forms of Ketorolac

  • Sohn, Young-Taek;Seo, Hyun-Ok
    • Archives of Pharmacal Research
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    • v.27 no.3
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    • pp.357-360
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    • 2004
  • Four crystal forms of ketorolac have been obtained by recrystallization in organic solvents under variable conditions. Different ketorolac polymorphs and pseudo polymorph were characterized by X-ray powder diffraction crystallography (XRD), Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). In the dissolution studies in water at $37{\pm}0.5^{\circ}C$ four crystal forms showed different patterns. The solubility of Form I were the highest. The solubility decreased in rank order: Form I> Form II > Form III > Form IV. Form land Form III were shown to have a good physical stability at room temperature for 60 days. However, Form II is converted to Form III and Form IV is converted to Form I after 60 days storage. Therefore, these observations indicate that crystalline polymorphism for ketorolac is readily inter-convertible and the relationship may have to taken into consideration in the formulation of the drug.

Kinetic Analysis of Energetic Materials Using Differential Scanning Calorimetry (DSC를 이용한 고에너지 물질의 반응속도식 추출과 활용)

  • Kim, Yoocheon;Park, Jungsoo;Yang, Seungho;Park, Honglae;Yoh, Jai-Ick
    • Journal of the Korean Society of Propulsion Engineers
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    • v.19 no.1
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    • pp.33-41
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    • 2015
  • The kinetic analysis of energetic materials using Differential Scanning Calorimetry (DSC) is proposed. Friedman Isoconversional method is applied to DSC experiment data and AKTS software is used for analysis. The proposed kinetic scheme has considerable advantage over the standard method based on One-Dimenaionl Time to Explosion (ODTX). Reaction rate and product mass fraction simulation are conducted to validate extracted kinetic scheme. Also a slow cook-off simulation is implemented on $B/KNO_3$ for validating the applicability of the extracted kinetics scheme to a practical thermal experiment.