• Title/Summary/Keyword: Thermogravimetric Analysis

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Synthesis and Characterization of Wholly Aromatic Polyester Liquid Crystalline Thermosets (전방향족 폴리에스터 열경화성 액정의 합성과 특성)

  • Moon, Hyun-Gon;Jung, Myung-Sup;Chang, Jin-Hae
    • Polymer(Korea)
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    • v.36 no.1
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    • pp.9-15
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    • 2012
  • We prepared a series of aromatic liquid crystals (LCs) based on wholly aromatic ester units with the reactive end group methyl maleimide by means of melt condensation method, and the resulting LCs were thermally crosslinked to produce liquid crystalline thermoset (LCT) films. The synthesized LCs and LCTs were characterized with Fourier transform infrared (FTIR) spectroscopy, wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), thermomechanical analysis (TMA), and polarizing optical microscopy (POM) with a hot stage. The glass transition temperature ($T_g$) and coefficient of thermal expansion are strongly affected by the mesogen units in their main chain structures. The $p$-substituted biphenyl LC was found to have the highest thermal property value.

Study on the Formulation of an Energetic Thermoplastic Propellant and its Properties(II) (고에너지 열가소성 추진제 제조 및 특성연구(II))

  • Kim, Han-cheol;Park, Eui-Yong;Jeong, Jea-Yun;Kim, Yoon-Gon;Choi, Sung-han;Kang, Tae-won;Oh, Kyeong-won
    • Journal of the Korean Society of Propulsion Engineers
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    • v.24 no.3
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    • pp.41-46
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    • 2020
  • In this study, measurement and analysis results from Differential scanning calorimetry(DSC) and Thermogravimetric analysis(TGA) on the newly developed high-energy thermoplastic elastomer(ETPE) propellant are described, followed by the previous study done under the same title as this paper [1]. The characteristics of high-energy thermoplastic propellant were also verified by conducting thermal analysis, and the LSGT, Shotgun & RQ Bomb test, was carried out as well. High energetic thermoplastic binders containing 45% of GAP(Glycidyl Azide Polymer), energetic plasticizer(DEGDN) and Oxidizer Aonium Perchlorate), RDX(reseach development explosive, cyclotrimethylenetrinitramine) were used to formulate the propellant.

Synthesis, characterization, and toxicity of multi-walled carbon nanotubes functionalized with 4-hydroxyquinazoline

  • Tahermansouri, Hasan;Mirosanloo, Atieh;Keshel, Saeed Heidari;Gardaneh, Mossa
    • Carbon letters
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    • v.17 no.1
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    • pp.45-52
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    • 2016
  • The attachment of 2-aminobenzamide to carboxylated multi-wall carbon nanotubes (MWCNTs)-COOH was achieved through the formation of amide bonds. Then, the functionalized MWCNTs, MWCNT-amide, were treated by phosphoryl chloride to produce MWCNT-quin. The products were characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, thermogravimetric analysis, derivative thermogravimetric, steady-state fluorescence spectroscopy, and solubility testing. MWCNT-quin showed photo-electronic properties, which is due to the attachment of the 4-hydroxyquinazoline groups to them as proved by steady-state fluorescence spectroscopy. This suggests intramolecular interactions between the tubes and the attached 4-hydroxyquinazoline. The toxicity of the samples was evaluated in human embryonic kidney HEK293 and human breast cancer SKBR3 cell lines, and the viable cell numbers were measured by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) after the cells were cultured for 24 h. Cellular investigations showed that the modified MWCNTs, particularly MWCNT-quin, have considerably significant toxic impact on SKBR3 as compared to HEK293 at the concentration of 5 µg/mL.

A Study on The Thermal Properties and Activation Energy of Rapidly Torrefied Oak Wood Powder using Non-isothermal Thermogravimetric Analysis (비등온 열중량분석법을 이용한 급속 반탄화 참나무 목분의 열적 특성과 활성화 에너지 연구)

  • Lee, Danbee;Kim, Birm-June
    • Journal of the Korean Wood Science and Technology
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    • v.44 no.1
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    • pp.96-105
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    • 2016
  • This study investigated thermal properties and activation energy ($E_a$) of torrefied oak wood powders treated with various torrefaction times (0, 5, 7.5, 10 min) by using non-isothermal thermogravimetric analysis at heating rates of 10, 20, $40^{\circ}C/min$ to check the feasibility of rapidly torrefied oak wood powders as a fuel. As the torrefaction time increases, onset of thermal decomposition temperature, lignin content, and the amount of final residue of torrefied oak wood powders were accordingly increased with reduced hemicellulose content. $E_a$ was determined by using Friedman and Kissinger models and respective R-square values were over 0.9 meaning very good availability of calculated $E_a$ values. The $E_a$ values of the samples were decreased with the increase of torrefaction time and the lowest $E_a$ value ob served in the torrefied oak wood powders treated for 7.5 min showed high feasibility of rapidly torrefied oak wood powder as a biomass-solid refuse fuel.

Study on Torrefaction Characteristics of Solid Biomass Fuel and Its Combustion Behavior (바이오매스 고형연료의 반탄화 특성 및 반탄화물의 연소특성에 관한 연구)

  • Lee, Weon Joon
    • Journal of the Korea Organic Resources Recycling Association
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    • v.23 no.4
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    • pp.86-94
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    • 2015
  • Torrefaction is a thermochemical process proceeded at the temperature around $250^{\circ}C$ in an inert gas condition. By torrefaction, the hemicellulose portions contained in biomass are broken down to change into the volatile gas which is removed from biomass eventually. The main purpose of biomass torrefaction is to improve the energy density of the biomass to minimize the transport energy consumption, though the flammability can be elevated for transportation. In this study two types of solid biomass fuel, waste wood and rice straw, were torrefied at various temperature range from $200^{\circ}C$ to $300^{\circ}C$ to evaluate the torrefied biomass characteristics. In addition torrefied biomass were tested to evaluate the combustion characteristics using TGA (Thermogravimetric Analysis). After the torrefaction of biomass, the C/H (carbon to hydrogen ratio) and C/O (carbon to oxygen ratio) were measured for aquisition of bio-stability as well as combustion pattern. Generally C/H ratio implies the soot formation during combustion, and the C/O ratio for bio-stability. By torrefaction temperature at $300^{\circ}C$, C/H ratio and C/O ratio were increased by two times for C/H and three times for C/O. The torrefied biomass showed similar TGA pattern to coal compared to pure biomass; that is, less mass decrease at lower temperature range for torrefied biomass than the pure biomass.

Preparation and Characterization of Polyurethane Microcapsules Containing Functional Oil (기능성 오일을 함유하는 폴리우레탄 마이크로캡슐의 제조 및 분석)

  • 김인회;서재범;김영준
    • Polymer(Korea)
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    • v.26 no.3
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    • pp.400-409
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    • 2002
  • Polyurethane microcapsules containing functional oil (citronella oil) were successfully prepared by conventional interfacial polymerization of tolulene 2,4-diisocyanate (TDI) and ethylene glycol (EG) and characterized by Fourier transform (FT-IR) spectroscopy, Ultraviolet spectroscopy, particle size analysis, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Tile effects of polymerization variables, such as surfactant concentration and agitation speed, on the particle size and particle size distribution were investigated. FT-IR spectroscopic data showed that citronella oil was successfully encapsulated in the microcapsule. Thermogravimetric analysis data showed that the microcapsule was thermally stable up to $220^{\circ}C$. The controlled release of the citronella oil present in the microcapsule core in a methanol medium was demonstrated by ultraviolet spectroscopy showing that the amount of released citronella oil was increased with increasing time. It was observed that the amount of released citronella oil was increased with increasing stirring speed and emulsifier concentration in the rnicrocapsule preparation step. Polyurethane microcapsules containing citronella oil showed excellent anti-moth property.

Determination of Wood Flour Content in WPC Through Thermogravimetic Analysis and Accelerator Mass Spectrometry (열중량 분석기와 질량가속기를 이용한 목재·플라스틱 복합재의 목질섬유함량 분석)

  • Gwon, Jae-Gyoung;Lee, Dan-Bee;Cho, Hye-Jung;Chun, Sang-Jin;Choi, Don-Ha;Lee, Sun-Young
    • Journal of the Korean Wood Science and Technology
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    • v.45 no.5
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    • pp.572-579
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    • 2017
  • Determination of the wood content in wood plastic composite (WPC) is crucial to form reliable WPC market. WPC with simple formulation consisting of only two components (wood flour and polypropylene) was examined using thermogravimetric analysis (TGA) and accelerator mass spectrometry (AMS) for determining wood content in the WPC. TGA method using derivative peak temperature (DTp) of polypropylene under low heating rate ($5^{\circ}C/min$) showed more reliable calibration curve and lower error factor compared to method of using the percentage of weight loss of wood flour. In addition, AMS using bio-based carbon content showed greater reliability for the determination of wood content in the WPC in comparison with the TGA method.

Kinetic Studies of the Catalytic Low Rank Coal Gasification under CO2 Atmosphere (CO2분위기하에서 저급석탄 촉매가스화 반응 특성 연구)

  • Park, Chan Young;Park, Ji Yun;Lee, Si Hoon;Rhu, Ji Ho;Han, Moon Hee;Rhee, Young Woo
    • Korean Chemical Engineering Research
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    • v.50 no.6
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    • pp.1086-1092
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    • 2012
  • In this study, kinetic studies and analysis of the produced syngas were conducted for low rank coal gasification under $CO_2$ atmosphere. 6 coals were analyzed to measure amount of sulfur and ash by proximate and ultimate analyses. And then they were analyzed to select suitable sample by using Thermogravimetric analyzer (TGA). Selected coal sample Samhwa was mixed with catalysts. Mixed samples with catalysts were used to get activation energy under $CO_2$ atmosphere by using Kissinger's method and shrinking core model (SCM). Also, analysis of produced syngas was performed by Gas Chromatography (GC). In this experiment, activation of the $K_2CO_3$ was the best performance, and result of the analysis of the syngas showed similar trend with result of the activation energy.

A Study on the Kinetics of Thermal Degradation of Polyethylene (폴리에틸렌 열분해의 속도론적 연구)

  • Kim, Myung Soo;Oh, Sea Cheon;Lee, Hae Pyeong;Kim, Hee Taik;Yoo, Kyong Ok
    • Applied Chemistry for Engineering
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    • v.10 no.4
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    • pp.548-556
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    • 1999
  • The thermal degradation of polyethylene has been studied using a nonisothermal thermogravimetric technique under a nitrogen 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 have been analyzed by a variety of analytical methods such as Kissinger, Freeman-Carroll, Flynn-Wall, Coats-Redfern, Chatterjee-Conrad, Friedman, Horowitz-Metzger, Ozawa and Denq methods. The comparative works for the kinetic results obtained from various methods should be performed to determine the kinetic parameters, because three are tremendous differences in the calculated kinetic parameters depending upon the mathematical method taken in the analysis. From this work, it was found that the apparent activation energy of HDPE was larger than those of LDPE and LLDPE.

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Analysis and hazard classification for the monomers in thermoplastic resins (열가소성 수지의 단량체 분석 및 유해성 분류)

  • Lee, Kwon Seob;Jo, Ji-Hun;Choi, Jin hee;Choi, Sung bong;Lee, Jong Han;Yang, Jeong Sun
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.17 no.4
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    • pp.322-334
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    • 2007
  • This study covers the investigation of the actual condition in the workplace to produce plastics products using synthetic resins and the investigation on the trends amount of the domestic production of thermoplastic resins. To analyze the monomers included in thermoplastic resins frequently used in the workplace, we analyzed thermal characteristics for test compounds using thermogravimetric analysis and did the qualitative analysis using Pyrolyzer GC-MSD & TDS GC-MSD. And then we classified the health hazard of monomers based on GHS classification criteria using information toxicity & carcinogenicity. The number of the workplace to produce plastics products among all domestic manufacturers of 73,884 was 4,391 (5.94%). The number of workers to produce plastics products among all workers of 2,522,750 in all domestic manufacturers was 104,971 (4.16%). The amount of production per year for thermoplastic resins is in the order of PP, HDPE, LDPE, PVC, ABS, PS and such compounds was producing over 1 Million ton per year each. The classification result based on GHS classification criteria for 22 main compounds included thermoplastic resins says 2 compounds of acrylonitrile, naphthalene are in Acute oral category 3 and benzene is in Acute dermal category 1. The classification results of health hazard of carcinogenicity based on IARC & ACGIH carcinogen classification says 2 compounds of benzene, vinyl chloride are in category 1A (known to be human carcinogens).