• 한국염색가공학회지
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• 제11권5호
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• pp.44-54
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• 1999

Poly(ethylene 2,6-naphthalate), PEN, is a relatively well-known polymer used for engineering purposes. Naphthalene ring provides rigidity to the polymer backbone, thus, it elevated the glass transition temperature and enhanced mechanical properties. The structure and properties of PEN affect a processing conditions severely, and the high-thermal stability have been had a poor thermal processibility. Hence, the basic mechanism of solvent drawing, is very much the same as that of thermal drawing from glassy state since both involve the inducement of segmental mobility. The former achieves the goal by use of chemical energy, and the latter does so by use of thermal energy. Generally, the sorption of the solvent by the polymer has a plasticizing effect, and leads to a lowering of the glass transition temperature, $T_g$. In this paper, the dynamic viscoelasticity behavior in liquid-drawing process of an unoriented amorphous PEN films were investigated using Rheovibron. The results are as follows ： (1) For the drawing in silicone oil, the drawing below $T_g$. had $\alpha{2}$-dispersion due to an inhomogeneous taut structure. (2) For the drawing in water, the inhomogeneous taut structure reduced by the effect of plasticization even below $T_g$. (3) For the drawing in butanol, the only aliphatic segment in PEN have some molecular mobility but the mobility of the aromatic segment having naphthalene ring is nearly impossible. (4) For the drawing in dioxane/water mixing solvent, the solvent effect is complementary each other and accordingly the entire molecular conformation have stable state. (5) For the drawing in dioxane/butanol mixing solvent, the inhomogeneity of the taut structure and the aromatic segment increase with increasing the temperature and this tendencies correspond with that of the draw ratio.

• 마이크로전자및패키징학회지
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• 제15권2호
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• pp.7-15
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• 2008

본 논문에서는 ACF를 이용한 CCM용 COF 어셈블리의 실장 기술을 연구하고 COF 어셈블리의 신뢰성 분석을 수행하였다. 열팽창계수, 모듈러스, 유리전이온도 등 경화 후 ACF의 열-기계적 물성들을 분석하였으며, ACF의 경화거동 결과를 바탕으로 COF 접합공정 온도 및 시간을 최적화하였으며, 도전입자의 변형 관찰 및 전기적 접촉 저항 측정을 통해 본딩 압력에 대한 최적화를 수행하였다. 또한 ACF 물질 특성이 COF어셈블리의 신뢰성에 미치는 영향을 알아보기 위해 열-싸이클 시험, 고온 유지 시험, 고온고습 시험을 수행하였다. 신뢰성 시험 수행 후 ACF를 이용한 COF 어셈블리의 신뢰성에 가장문제가 되고 있는 점은 열-싸이클 신뢰성 시험에서 나타난 ACF joint의 접촉 저항 증가 문제였고, 이는 ACF 자체의 열-기계적 물성과 밀접한 관계가 있음을 확인하였다.

• 한국재료학회지
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• 제32권12호
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• pp.515-521
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• 2022

Various types of optical materials and devices used in special environments must satisfy durability and optical properties. In order to improve the durability of zinc sulfide multispectral (MS ZnS) substrates with transmission wavelengths from visible to infrared, Ge-Sb-Se-based chalcogenide glass was used as a sealing material to bond the MS ZnS substrates. Wetting tests of the Ge-Sb-Se-based chalcogenide glass were conducted to analyze flowability as a function of temperature, by considering the glass transition temperature (T_g) and softening temperature (T_s). In the wetting test, the viscous flow of the chalcogenide glass sample was analyzed according to the temperature. After placing the chalcogenide glass disk between MS ZnS substrates (20 × 30 mm), the sealing test was performed at a temperature of 485 ℃ for 60 min. Notably, it was found that the Ge-Sb-Se-based chalcogenide glass sealed the MS ZnS substrates well. After the MS ZnS substrates were sealed with chalcogenide glass, they showed a transmission of 55 % over 3~12 ㎛. The tensile strength of the sealed MS ZnS substrates with Ge-Sb-Se-based chalcogenide glass was analyzed by applying a maximum load of about 240 N, confirming its suitability as a sealing material in the far infrared range.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전기물성,응용부문
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• pp.134-136
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• 2003

In this work, we have seen the effect of hole-transporting layer in organic light-emitting diodes using N,N'-biphenyl-N,N'-bis-(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine(TPD) and N,N'-biphenyl-N,N'-bis-(1-naphenyl)-[l,l'-biphenyl]-4,4'-diamine(NPB). NPB is regarded as a better hole trans porting material than TPD, since it has a higher glass transition temperature($T_g$). And current-voltage, luminance-voltage and external quantum efficiency of device were measured with the thickness variation of buffer layer using copper phathalocyanine(CuPc) am polytetrafluoroethylene (PTEE) at room temperature. We have obtained an improvement of External quantum efficiency when the CuPc 30[nm] and PTFE 1.0[nm] is used.

• 폴리머
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• 제37권1호
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• pp.41-46
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• 2013

유무기 하이브리드 나노 물질인 polyhedral oligomeric silsesquioxane(POSS)를 첨가한 diglycidyl ether of bisphenol A(DGEBA) 에폭시/방향족 아민계를 다양한 경화온도에서 등온으로 반응시킨 후 유리전이온도($T_g$)와 전환율(${\alpha}$)을 DSC를 이용하여 측정하였다. 등온 경화시간에 따른 $T_g$의 변화 데이터를 임의로 설정된 기준 온도에서 수평 이동시켜 반응초기에 해당하는 속도우세 구간에서 서로 겹치게 하여 이때 필요한 이동 인자를 구하였으며, 이를 이용하여 활성화 에너지를 결정하였다. 또한 POSS가 $T_g$ 및 ${\alpha}$에 미치는 영향을 조사하였으며 이들의 관계를 알기위하여 DiBenedetto식을 이용하여 분석하였다.

• 폴리머
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• 제26권6호
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• pp.737-744
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• 2002

결정성 폴리부틸렌나프탈레이트 (PBN)와 비결정성 폴리비닐페놀 (PVPh)로 구성된 2 성분계 고분자 블렌드의 열역학적 상용성을 시차주사열분석 (DSC)과 푸리에변환 적외선 (FTIR) 분광분석으로 조사하였다. PBN/PVPh 블렌드의 DSC 측정 결과로부터 블렌드 전 조성에서 단일 유리전이온도 (T$_{g}$ )가 확인되었으며, 블렌드 내의 PVPh 조성이 증가함에 따라 PBN 결정질의 용융점(T$_{m}$ ) 강하가 관찰되었다. 고분자 블렌드의 단일 T$_{g}$ 및 T$_{m}$ 강하 현상은 PBN/PVPh 블렌드가 분자 수준에서의 열역학적 상용성이 있음을 보여준다. PBN의 에스테르 카르보닐기와 PVPh의 히드록실기 사이에 강한 분자 간 수소결합이 형성됨을 FTIR 분석에 의하여 확인할 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제30권2호
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• pp.334-338
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• 2009

Trifunctional epoxy resin triglycidyl paraaminophenol (TGPAP)/$CaCO_3$ nanocomposites were prepared using the melt blending method. The effects of nano-$CaCO_3$ content on the thermal behaviors, such as cure behavior, glass transition temperature ($T_g$), thermal stability, and the coefficient of thermal extension (CTE), were investigated by several techniques. Differential scanning calorimetry (DSC) results indicated that the cure reaction of the TGPAP epoxy resin was accelerated with the addition of nano-$CaCO_3$. When the nano-$CaCO_3$ content was increased, the $T_g$ of the TGPAP/$CaCO_3$ nanocomposites did not obviously change, whereas the crosslinking density was linearly increased. The nanocomposites showed a higher thermal stability than that of the neat epoxy resin. This result could be attributed to the increased surface contact area between the nano-$CaCO_3$ particles and the epoxy matrix, as well as the high crosslinking density in the TGPAP/$CaCO_3$ nanocomposites. The CTE of the nanocomposites in the rubbery region was significantly decreased as the nano-$CaCO_3$ content was increased.

• 한국염색가공학회지
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• 제3권3호
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• pp.23-28
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• 1991

Poly(1, 4-cyclohexanedimethylene/ethylene terephthalate), PCET was prepared by condensing 1, 4-cyclohexanedimethanol(CHDM) and ethylene glycol with dimethylterephthalate(DMT), and some thermal properties of PCET were studied by DSC at a heating rate $20^{\circ}C$min. On increasing the CHDM content in PCET up to 20 mole%/DMT, the glass transition temperature(Tg) decreased a little and the crystallizability reduced sharply, and from 20 to 50 mole %/DMT the $T_g$ did not changed and the crystallization temperature was not detected. But on increasing the CHDM content above 70 mole %/DMT the TEX>$T_g$/ and the melting temperature increased.

• 한국초전도ㆍ저온공학회논문지
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• 제17권4호
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• pp.30-33
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• 2015

We report the synthesis of Ni-doped $BaFe_2Se_3$ single crystals by using a flux method. X-ray diffraction (XRD) of $Ba(Fe_{1-x}Ni_x)_2Se_3$ shows a gradual peak shift with an increase in the nominal Ni-doping rate, x = 0, 0.05, and 0.10, due to a decrease in unit-cell volume. All samples show a spin glass transition, and temperature dependence of magnetic susceptibility shows a negligible change in the spin-glass transition temperature ($T_g$) with Ni concentration x. The temperature dependence of electrical resistivity for $BaFe_2Se_3$ shows an insulating behavior, and the resistivity value at 295 K and the activation energy ($E_a$) obtained from the Arrhenius plot decrease with increasing x. These results suggest that the Ni doping can be effectively worked as a dopant for electron charge carriers, but is less efficient in controlling the magnetic property, such as spin glass transition, in the $BaFe_2Se_3$ compound.

• 접착 및 계면
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• 제23권4호
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• pp.137-143
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• 2022

본 연구에서는 신발 및 의류용 접착제로 접착력과 굴곡성이 우수한 폴리우레탄 아크릴레이트 수지를 합성하기 위하여 폴리에스테르 폴리올인 poly(tetramethylene adiphate glycol) (PTAd)와 폴리에테르 폴리올인 poly(tetramethylene ether glycol) (PTMG)를 4,4'-methylene diphenyl diisocyanate (MDI), isophorone diisocyanate (IPDI), 1,4-butandiol (1,4-BD), 2-ydroxyethyl methacrylate (2-HEMA), dibutyl amine (DBA)와 함께 사용하여 폴리우레탄 아크릴레이트를 합성하였으며, 폴리올을 병용한 폴리우레탄 아크릴레이트의 열적·기계적 특성, 접착력 및 굴곡성을 검토하였다. 합성된 폴리우레탄 아크릴레이트의 유리전이온도는 -70~-40 ℃ 범위로 확인되었으며, PTAd 함량이 증가함에 따라 유리전이온도, 분해온도, 인장강도, 접착력 및 내열성이 증가하였고 반대로 신장률, 내수성 및 굴곡성은 감소되었다. 합성된 폴리우레탄 아크릴레이트는 PTAd와 PTMG 비율이 5:5일 때 높은 접착력과 굴곡성을 나타내었다.