• Title, Summary, Keyword: 시차 주사 열량 분석

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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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Effects of Annealing Process on the Crystallinity and Tensile Strength of PTFE (PTFE의 결정화도와 인장 강도에 미치는 풀림(annealing) 공정의 영향)

  • Kim, Jung-Teag;Kim, Eun-Bong;Kim, Si-Young;Ju, Chang-Sik
    • Korean Chemical Engineering Research
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    • v.48 no.1
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    • pp.53-57
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    • 2010
  • In this work, we made experimental studies on the annealing process of PTFE(polytetrafluoroethylene) at $290{\sim}350^{\circ}C$ and examined the effects on crystallinity and tensile strength of PTFE. The experiments were performed at air atmosphere and the processes progressed up to 8 hours. From measuring tensile strength and SEM(scanning electron microscopy) observation, we could know PTFE was anisotropic material due to the band structure. Crystallinity of raw and annealed PTFE was measured by DSC(differential scanning calorimetry). As a result, crystallinity of annealed PTFE decreased and tensile strength increased. Also, we could verify the relation between crystallinity and tensile strength of annealed PTFE was linear. Raw PTFE, however, dropped out from the linear relation. Finally, PTFE annealed at $350^{\circ}C$ for 6 hours showed the smallest crystallinity and the largest tensile strength.

Thermal and Mechanical Properties of Poly(lactic acid) Specimens Fabricated by Various Equal-channel Angular Extrusion Processes (다양한 방식의 등통로각압축공정으로 가공된 Poly(lactic acid) 시편들의 열 및 기계적 물성)

  • Liu, Xu-Yan;Jung, Si-In;Choi, Ho-Suk;Oh, Jun-Taek;Kim, Jong-Kuk
    • Korean Chemical Engineering Research
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    • v.49 no.2
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    • pp.206-210
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    • 2011
  • We fabricated rod-like poly(lactic acid)(PLA) specimens through applying various methods of equal-channel angular extrusion(ECAE) process and investigated the change of thermal and mechanical properties of specimens before and after each ECAE process. Combining three re-injection routes(A, BC, and C) and three pass counts(1, 2 and 4) allowed us to fabricate 7 different PLA specimens. Thermal properties of each specimen were measured by both differential scanning calorimeter and thermo-gravimetric analyzer. Shear strains of each specimen with respect to applied loads were measured by indentation hardness tester. Field emmision scanning electron microscopy was used to observe internal microstructure of cross-section of each specimen. The observed microstructures qualitatively supported the explanation of hardness test results. Among 7 specimens, PLA-P2A showed the biggest shear strain probably due to its dense microstructure.

Synthesis and Characterization of Transparent Copolyimide Films (II) (투명한 공중합체 폴리이미드 필름의 합성 및 특성 연구(II))

  • Park, Jong-Su;Chang, Jin-Hae
    • Polymer Korea
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    • v.33 no.4
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    • pp.313-318
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    • 2009
  • Copolyimides were synthesized from bis (3-aminophenyl) sulfone (APS) and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) containing a fluorine substituent ($-CF_3$) with different mole ratios of 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DSDA) containing a sulfone group (-$SO_2$-). The PI films were obtained from poly (amic acid) (PAA) by solution casting through thermal imidization on a glass plate. Wide-angle X-ray diffraction (XRD), scanning electron microscopy (FE-SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), universal tensile machine (UTM) measurements, and UV-Vis spectrometry were used to assess thermo-mechanical properties, morphology, and optical transparency. Thermal properties and optical transparency decreased with increasing DSDA mole fraction. In contrast, mechanical properties increased with increasing DSDA mole fraction. As compared to conventional PI films, however, the PI copolymer films in this work were found to exhibit better optical transparency.

Synthesis and Characterization of Transparent Copolyimide Films (I) (투명한 폴리이미드 공중합체 필름의 합성과 특성 연구 (I))

  • Park, Jong-Su;Chang, Jin-Hae
    • Polymer Korea
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    • v.32 no.6
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    • pp.580-586
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    • 2008
  • Copolyimides were synthesized from 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 1,3-bis(3-aminophenoxy)benzene (BAPB) with different mole ratios of 2,2-bis[4-(4-aminophenoxy)pheny1]hexafluoropropane (BAPP). The solution cast film of poly(amic acid) (PAA) was heat treated at different temperatures to create copolyimide films. The PI copolymer films were found to exhibit good optical transparencies. The thermomechanical properties, morphology, and optical transparency of PI films were examined using fourier transform infrared spectroscopy (FT-IR), wide-angle X-ray diffraction (XRD), scanning electron microscopes (SEM), differential scanning calorimeter(DSC), thermo-gravimetric analyzer (TGA), universal tensile machine (UTM), and IN - Vis. spectrometer. The glass transition temperature ($T_g$), ultimate strength, and initial modulus linearly increased with increasing BAPP mole fraction. However, thermal stability($T_D{^i}$) of the copolyimide remains constant regardless of BAPP loadings. It was found, however, that the optical transparency decreases slightly upon increasing the BAPP content because of the formation of the charge transfer complexes.

Preparation and Characterization of Sponge Using Porcine Small Intestinal Submucosa (돼지의 소장 점막하 조직을 이용한 스폰지의 제조 및 특성 결정)

  • 신혜원;김선화;장지욱;김문석;조선행;이해방;강길선
    • Polymer Korea
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    • v.28 no.2
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    • pp.194-200
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    • 2004
  • Porcine small intestine submucosa (SIS) has been widely used as a biomaterial without immunorejection responses. Crosslinked SIS sponges were characterized for the possibility of the bio-interactive wound dressings and tissue engineered scaffolds. SIS powders were dissolved in 3% acetic acid aqueous solution at 48hrs followed by pouring into mold and then fabricated by freeze-drying method. SIS sponge was prepared by crosslinked with 1-ethyl-(3-3-dimethyl aminopropyl) carbodiimide hydrochloride (EDC) solution (deionized water: ethanol=5:95) with 1-100mM concentration for 24 hrs and Iyophilized. SIS sponges were characterized by scanning electron microscopy, differential scanning calorimeter, and Fourier transform infrared spectrometer and were tested their porosity and water absorption ability. It was observed that the concentration of EDC might be exceeded 50 mM to get good physical characteristics. In conclusion, it seems that SIS sponge could be very useful for the applications of wound healing and tissue construction.

Preparation and Characterization of Calcium Alginate Microcapsules by Emulsification-Internal Gelation (에멀션-내부 젤화에 의한 알긴산 칼슘 마이크로캡슐의 제조 및 특성)

  • Park Soo-jin;Kang Jin-Young
    • Polymer Korea
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    • v.29 no.4
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    • pp.369-374
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    • 2005
  • In this work, the calcium alginate microcapsules containing lemon oil were prepared by emulsification-internal gelation and their potential use as aromatherapy was examined by the controlled release system. The lemon oil encapsulated in the alginate was successfully observed by Fourier transform (FT-IR) spectroscopy and differential scanning calorimeter (DSC) measurements. Analysis of the diameters and shapes of microcapsules was conducted by scanning electron microscopy (SEM). The mean diameters ranging from 4 to 7 um and encapsulation yield ranging from 50 to $85\%$ were obtained. The controlled release of the lemon oil at $37^{circ}$ was demonstrated by the infrared moisture determination (IMDB). It was found that the amount of released lemon oil decreased with increasing concentrations of alginate and $CaCl_2$ due to the higher the cross-linking density of the capsules prepared. The oil release from the capsule was measured as a function of physical force. We confirmed that the external factor could control the collapse of capsule wall and the release rate.

Effect of Isocyanate Index on the Physical Properties of Rigid Polyurethane Foam under Sea Water (해수에서 이소시아네이트 인덱스 변화가 경질폴리우레탄 폼의 물성에 미치는 영향)

  • Kang, Sungkoo;Cho, Ilsung;Kim, Sangbum
    • Applied Chemistry for Engineering
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    • v.19 no.4
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    • pp.427-431
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    • 2008
  • The rigid polyurethane foams (PUF) were prepared using polyols with 90, 110, 130, and 150 isocyanate index. The effect of sea water on the physical properties of PUF with the increase in isocyanate (NCO) index and ageing time was investigated. Tensile strengths and compressive strengths of the PUFs decreased up to 10% and 7% with an increase in ageing time, respectively. Cell morphology of the PUF under sea water was turned out to be the same as that in the ambient condition. It was observed that $T_g$ and tensile modulus of the PUF under sea water increased. The results showed an additional cross-link reaction of non-reacted MDI and the change of NCO peak as observed from FT-IR spectrum.

Preparation of Quaternary Energetic Composites by Crystallization and Their Thermal Decomposition Characteristics (결정화에 의한 4성분계 에너지 복합체 제조 및 열분해 특성)

  • Kim, Byoung-Soo;Kim, Jae-Kyeong;Ahn, Ik-Sung;Kim, Hyoun-Soo;Koo, Kee-Kahb
    • Applied Chemistry for Engineering
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    • v.30 no.2
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    • pp.178-185
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    • 2019
  • Three spherical quaternary composites composed of metal/metal oxide/high explosive/oxidizer were prepared by a crystallization/agglomeration process. From the characteristics of composites by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), the shortening of the decomposition zone of high explosives in the quaternary composite was observed, which may be attributed to the autocatalytic reaction caused by $ClO_2$ or HCl which are ammonium perchlorate (AP) degradation products. The activation energy analysis showed that the activation energy abruptly decreases at the end of the decomposition zone of high explosives, and it was considered to be caused by $HNO_2$ which is common in decomposition products of high explosives. The activation energy predicted from complex pyrolysis results by the distributed activation energy model (DAEM) showed much better in accuracy than those by model-fitting methods such as Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa models.

Characteristic of Underfill with Various Epoxy Resin (에폭시 수지에 따른 언더필의 특성에 관한 연구)

  • Noh, Bo-In;Lee, Jong-Bum;Jung, Seung-Boo
    • Journal of the Microelectronics and Packaging Society
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    • v.13 no.3
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    • pp.39-45
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    • 2006
  • This study was investigated the thermal properties of underfill with various epoxy resins using thermal analysis methods such as differential scanning calorimetry (DSC), thermo gravimetry analysis (TGA), dynamic mechanical analysis (DMA) and thermo-mechanical analysis (TMA). And, the adhesion strength of the underfills/FR-4 substrate was evaluated. The glass transition temperature (Tg) of underfill which was composed the cycolaliphatic epoxy resin was lower than that of underfill which was not composed the cycolaliphatic epoxy resin. The thermal degradation of underfill was composed of two processes, which involved chemical reactions between the degrading polymer and oxygen from the air atmosphere. The coefficient of thermal expansion (CTE) of underfill which was composed the cycolaliphatic epoxy resin was higher than that of underfill which was not composed the cycolaliphatic epoxy resin. The excessive curing temperatures caused a weak boundary layer of epoxy resin, which resulted in a deterioration of mechanical properties in the epoxy resin and thus led to poor adhesion property between the underfill/FR-4 substrate.

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