• Title, Summary, Keyword: 시차 주사 열량 분석

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A Study on Morphology and Mechanical Properties of Biodegradable Polymer Nanocomposites (생분해성 고분자 나노복합체의 형태학 및 기계적 특성 연구)

  • Jang, Sang Hee
    • Clean Technology
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    • v.19 no.4
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    • pp.401-409
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    • 2013
  • BBiodegradable polymers have attracted great attention because of the increased environmental pollution by waste plastics. In this study, PLA (polylactic acid)/Clay-20 (Cloisite 20) and PLA (polylactic acid)/PBS (poly(butylene succinate)/Clay-20 (Cloisite 20) nanocomposites were manufactured in a twin-screw extruder. Specimens for mechanical properties of PLA/Clay-20 and PLA/PBS (90/10)/Clay-20 nanocomposites were prepared by injection molding. Thermal, mechanical, morphological and raman spectral properties of two nanocomposites were investigated by differential scanning calorimetry (DSC), tensile tester, scanning electron microscopy (SEM) and raman-microscope spectrophotometer, respectively. In addition, hydrolytic degradation properties of two nanocomposites were investigated by hydrolytic degradation test. It was confirmed that the crystallinity of PLA/Clay-20 and PLA/PBS/Clay-20 nanocomposite was increased with increasing Clay-20 content and the Clay-20 is miscible with PLA and PLA/PBS resin from DSC and SEM results. Tensile strength of two nanocomposites was decreased, but thier elongation, impact strength, tensile modulus and flexural modulus were increased with an increase of Clay-20 content. The impact strength of PLA/Clay-20 and PLA/PBS/Clay-20 nanocomposites with 5 wt% of Clay-20 content was increased above twice than that of pure PLA and PLA/PBS (90/10). The hydrolytic degradation rate of PLA/Clay-20 nanocomposite with 3 wt% of Clay-20 content was accelerated about twice than that of pure PLA. The reason is that degradation may occur in the PLA and Clay-20 interface easily because of hydrophilic property of organic Clay-20. It was confirmed that a proper amount of Clay-20 can improve the mechanical properties of PLA and can control biodegradable property of PLA.

A Study on the Fabrication of Fe Based Alloy Powder for Laser Welding (레이저 용접용 Fe계 합금 분말 제조에 관한 연구)

  • Lee, Jong-Jae;Son, Young-San
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.8
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    • pp.3315-3318
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    • 2012
  • In this study, Fe-base alloy powder was prepared by gas atomizing method. Shape and crystal structure of the powder were investigated by FESEM, X-ray diffraction, and DSC. The powder was produced in a spherical shape, with a size of 45 ~ 90 ${\mu}m$. X-ray diffraction analysis revealed that the powder was fully amorphous, showing typical broad amorphous peak. From DSC analysis, Tg and Tx that are generally found in a bulk amorphous alloy were also observed in the alloy powder. Tg and Tx of the powder were $530^{\circ}C$ and $560^{\circ}C$, respectively. These results suggest us that the bulk amorphous alloy (BMG) powder prepared in this study is applicable to laser welding.

Study on the Aging Behaviors of a Rapidly Solidified Al-Li-Zr Alloy by Differential Scanning Calorimetry (열분석 방법에 의한 급냉응고 Al-Li-Zr 합금의 시효거동 연구)

  • Hong, Yeong-Jun;Gang, Jeong-Yun;Kim, In-Bae;Lee, Sang-Rae
    • Korean Journal of Materials Research
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    • v.5 no.4
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    • pp.405-411
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    • 1995
  • 급냉응고된 Al-3.51wt%Li-0.34wt%Zr 합금의 시효거동을 시차주사열량계(DSC)에 의한 열분석 방법으로 조사하였다. DSC에 의한 비열측정 결과 $\delta$’의 석출에 의한 발열반응과 $\delta$, $\beta$ 및 복합석출상의 석출에 의한 발열반응을 확인하였으며 $\delta$’ 및 $\delta$의 재고용에 의한 2개의 흡열반응을 확인하였다. 7$0^{\circ}C$ 저온시효시 $\delta$’의 석출에 의한 발열반응 이전에 흡열반응이 나타났으며 이것은 $\delta$’ 석출 이전에 $\delta$’ 전구생성물이 형성되었음을 의미한다. DSC 곡선상에 나타난 발열과 흡열곡선을 해석하여 얻은 $\delta$’상 석출과 재고용의 활성화에너지값은 각각 83KJ/mol과 98KJ/mol로서 Al-Li 2원계 및 Al-Li-Mg에 비해 높은 값을 나타내엇으며, 시효에 의한 강화가 일어나 DSC에 의한 비열변화 조사결과 나타난 $\delta$’상 석출 완료 시효조건점 (21$0^{\circ}C$, 1시간)에서 최고경도값(Hv 160)을 나타내었다.

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Thermal Decomposition Kinetics of ZPP as a Primary Charge of Initiators (착화기용 ZPP의 열분해 특성)

  • Kim, Junhyung;Seo, Taeseok;Ko, Seungwon;Ryu, Byungtae
    • Journal of the Korean Society of Propulsion Engineers
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    • v.19 no.5
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    • pp.15-21
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    • 2015
  • The thermal decomposition characteristics of the ZPP(Zirconium/Potassium perchlorate), widely used as a primary charge of initiators, were investigated by differential scanning calorimetry(DSC). The DSC results with different heating rates were elaborated with AKTS-Thermokinetics software for the determination of the kinetic parameters of the thermal decomposition of ZPP. There was good agreement between the experimental and the simulation curves, based on the determined kinetic parameters, which indicates the validity of the kinetic description of the thermal decomposition process of ZPP.

The Analysis on Properties of Epoxy/MWCNT for Bonding CFRP to Steel Plates (CFRP와 금속 재료의 접합을 위한 epoxy/MWCNT의 특성 분석)

  • Yoo, Sung-Hun;Kwon, Il-Jun;Shin, Dong-Woo;Park, Sung-Min;Yeum, Jeong-Hyun
    • Composites Research
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    • v.30 no.3
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    • pp.215-222
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    • 2017
  • The effect of a multi walled carbon nanotubes (MWNCT) on the adhesive properties and thermal properties of epoxy were studied by double lap-shear tests. Epoxy/MWCNT resins were prepared from a different amount of the MWCNT incorporated into the epoxy resins (araldite 2011). Steel plates and carbon fiber reinforced plastics (CFRP) were chosen as materials. Mechanical tests were performed by a universal testing machine (UTM). The analysis of thermal properties were conducted by a thermogravimetric analyzer (TGA) and a differential scanning calorimetry (DSC). The fracture surface morphology was examined using a scanning electron microscopy (SEM) and optical microscope. Compared to neat epoxy, it was found that the mechanical properties of epoxy/MWCNT resins are increased.

Liquid Crystalline Thermoset Films Based on Wholly Aromatic Copolymers (전방향족 공중합체의 열경화성 액정필름)

  • Moon, Hyun-Gon;Ahn, Yong-Ho;Chang, Jin-Hae
    • Polymer Korea
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    • v.34 no.4
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    • pp.369-375
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    • 2010
  • We used melt polymerization method to prepare a series of aromatic liquid crystals (LCs) based on aromatic ester and amide units with the reactive methyl-maleimide end group, and then the resulting thermally cross-linked LCs to produce LC thermoset films by means of solution casting and the followed heat treatment. The synthesized LCs and LCTs were characterized by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), thermomechanical analysis (TMA), X-ray diffractometry (XRD), and polarizing optical microscopy (POM) with a hot stage. All of the LCs prepared by melt polymerization method formed smectic mesophases. The thermal properties of the LC and LCT films were strongly affected by the mesogen units in the main chain structures. The thermal expansion coefficients of samples were in the range of 27.72~50.95 ppm/$^{\circ}C$.

Characterization of PMMA/MWNT Composites Fabricated by a Twin Screw Extruder (이축 압출기를 이용하여 제조된 PMMA/MWNT 복합체의 특성 분석)

  • Woo, Jong-Seok;Lee, Geon-Woong;Kye, Hyoung-San;Shin, Kyung-Chul;Bang, Dae-Suk
    • Elastomers and Composites
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    • v.42 no.3
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    • pp.151-158
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    • 2007
  • MWNTs have been widely investigated due to unique properties of such as good electrical conductivity and thermal stability in polymer composites industries. This paper established the procedure to fabricate PMMA/MWNT composites by a modular intermeshing co-rotating twin screw extruder with L/D ratio of 42. The electrical properties of PMMA/MWNT composites with different content of MWNT have been investigated. A sheet resistance percolation was observed at 4 wt% of MWNT for the melt processed composites. Sheet resistance of PMMA/MWNT composite film containing 4 wt% of MWNT was nearby $10^4{\Omega}/sq$ and this shows the possibility of potential application to EMI (Electronic Magnetic Interference) shielding materials. The characteristics of composites were analyzed by TGA, DSC, and SEM. In addition, MFI (Melt Flow Index) has been measured to analyze the rheological property.

Characterizations of Flexible Clay-PVA Hybrid Films: Thermo-optical Properties, Morphology, and Gas Permeability (유연한 점토-폴리(비닐 알코올) 하이브리드 필름의 특성 연구: 열적.광학적 성질, 모폴로지, 및 가스 투과성)

  • Shin, Ji-Eun;Ham, Mi-Ran;Kim, Jeong-Cheol;Chang, Jin-Hae
    • Polymer Korea
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    • v.35 no.5
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    • pp.402-408
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    • 2011
  • To improve $Na^+$-saponite(SPT) film flexibility, we prepared SPT hybrid clay films with various poly(vinyl alcohol) (PVA) concentrations(0~10 wt%) using the solution intercalation method. In this study, we investigated the thermo-optical properties, morphology, and gas permeability of the SPT hybrid films. We also examined the relationship between the film properties and PVA content using wide angle X-ray diffraction measurements(XRD), field emission scanning electron microscopy(FESEM), differential scanning calorimetry(DSC), thermogravimetric analysis(TGA), thermomechanical analysis(TMA), ultraviolet-visible(UV-vis) spectroscopy, and oxygen transmission rate($O_2$TR) testing. The properties of the clay hybrid films were strongly affected by PVA filler content. The presence of a small amount of PVA was sufficient to improve the flexibility of SPT hybrid films.

Preparations and Release Property of Poly(ε-caprolacton)/ethyl cellulose Microcapsule Containing Pluronic F127 (Pluronic F127을 함유하는 Poly(ε-caprolacton)/ethyl cellulose 마이크로 캡슐의 제조 및 방출 특성)

  • Hong, Yeon Ji;Kim, Jin-Chul
    • Applied Chemistry for Engineering
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    • v.20 no.6
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    • pp.632-637
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    • 2009
  • Poly(${\varepsilon}-caprolacton$)/ethyl cellulose (PCL/EC) microcapsules containing pluronic F127 were prepared by a spray drying method. The aqueous phase, 20% of pluronic F127 was dissolved in distilled water, and the organic phase, 5% of PCL and EC were dissolved in dichloromethane. The microcapsules were obtained by spray drying the water-in-oil (W/O) emulsion. According to the data of scanning electron microscopy and particle analyzer, tens of micro size microcapsules were observed. On a differential scanning calorimeter, the phase transition temperatures of microcapsules were observed and they were found around those of pluronic F127 and poly(${\varepsilon}-caprolacton$), which were the main components of the microcapsules. At the range of $30{\sim}45^{\circ}C$, temperature-dependent release properties were investigated using fluorescein isothicyanate-dextran (FITC-dextran) and blue dextran as a model drug. When the temperature was increased, the degree of release of microcapsule was also increased. FITC-dextran, the relative low molecular weight, was more released than blue-dextran.

Gelatinization Properties of Waxy Black Rice Starch (찰흑미 전분의 호화 특성)

  • Choi, Gyeong-Cheol;Na, Hwan-Sik;Oh, Geum-Soon;Kim, Sung-Kon;Kim, Kwan
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.34 no.1
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    • pp.87-92
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    • 2005
  • This study was investigated to examine gelatinization properties of waxy black rice starches. X-ray diffraction patterns in raw starches showed traditional A type of cereals. The crystalline regions of both black rice and Shinsunchalbyeo starches disappeared when temperature increased to $65^{\circ}C$ where the crystalline regions of two starches changed to amorphous ones. Scanning Electron Microscope showed that granule type of Shinsunchalbyeo starch was more collapsed compared to that of black rice starch heated at 6$0^{\circ}C$. Gelatinization in both samples completed when samples were heated at 63$^{\circ}C$. The results by Differential Scanning Calorimetry (DSC) revealed that gelatinization patterns were similar in both samples. In Rapid Visco Analyzer examination, there was no difference in peak viscosity, breakdown, final viscosity and setback between Shinsunchalbyeo and waxy black rice starches.