• Korea-Australia Rheology Journal
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• 제11권4호
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• pp.269-273
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• 1999

Immiscible polymer blends containing a liquid crystalline polymer dispersed phase can be described by existing blend theories when the dispersed-phase droplets are large relative to the orientation correlation length ("domain size") of the LCP. There does not appear to be an interfacial contribution to the linear viscoelastic properties of the blend from droplets smaller than the correlation length. Polyester blends, where interfacial interactions occur between the LCP and the matrix, exhibit a reduction in viscosity to below the viscosity of either component at low shear rates, where the droplet morphology is spherical. These anomalies cannot be explained in the context of existing theory.ng theory.

• Applied Microscopy
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• 제45권2호
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• pp.58-62
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• 2015

Formation of an icosahedral phase in the bulk glass forming $Ti_{40}Zr_{29}Be_{14}Cu_9Ni_8$ alloy during crystallization from amorphous phase and solidification from melt is investigated. The icosahedral phase with a size of 10 to 15 nm forms as a thermodynamically stable phase at intermediate temperature during the transformation from amorphous to crystalline phases such as Laves and ${\beta}$-(Ti-Zr) phases, indicating that the existence of the icosahedral cluster in the undercooled liquid. On the other hand, the icosahedral phase forms as a primary solidification phase even though the Laves phase is stable at high temperature, which is can be explained based on the high nucleation rate of icosahedral phase relative to that of competing crystalline Laves phase due to lower interfacial energy between icosahedral and liquid phases.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1998년도 가을 학술발표회논문집
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• pp.236-239
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• 1998

The in situ composites based on poly(ethylene 2,6-naphthalate) and thermotropic liquid crystalline polymer (LCP) have been an area of increasing interest and study, since LCP exhibits high chemical stabilities and excellent thermo mechanical properties such as high strength and modulus. In a binary, however, poor compatibility and interfacial adhesions between two phases frequently results in deteriorated mechanical properties. (omitted)

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1998년도 가을 학술발표회논문집
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• pp.94-97
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• 1998

We have been studying :he synthesis of thermotropic polyurethanes, based on structural modifications by means of (i) the introduction of bulky substituent group in the aromatic ring to decrease the degree of lateral packing, (ii) the copolymerization of two kinds of monomers having different alkylene lengths to lower the regularity of the polymer structure, and (iii) the use of nonlinear monomers to lower the persistence length of the polymer chain in the liquid crystalline phase and to decrease the lateral interactions in the solid state. (omitted)

• 한국응용과학기술학회지
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• 제28권3호
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• pp.313-320
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• 2011

Encapsulation of L-ascorbic acid(AA) into BGsome was attempted to improve its stability. BGsome is a bio-compatible vesicular system prepared by dispersion of hydrated liquid crystalline phase formed through hydration of 1,3-butylene glycol(BG)-dissolved lecithin with an aqueous solution containing hydrophilic component. The characteristics of AA encapsulated BGsome, such as droplet size, surface charge, and solution appearance, was investigated. The concentration of AA solution had considerable effect on droplet size and surface charge of BGsome. Several tens nanometer droplet made by sonication treatment did not showed any change of size with storage time. Stability of AA was improved by encapsulation into BGsome, which was verified through DPPH test and HPLC assay.

• 유변학
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• 제7권3호
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• pp.250-260
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• 1995

스크류 압출기로 제조한 poly(ether ether ketone) (PEEK)과 p-hydroxy benzoic acid/poly(ethylene tere-phthalate) (HBA/PET)의 공중합체인 열방성 액정 고분자의 블렌드 를 전조성에 대하여시차 주사 열분석기 (DSC)와 주사전자현미경(SEM)을 이용하여 연구하 였다. 측정된 유리전이 온도와 유리전이 온도에서의 열용량 증가분으로부터 PEEK가 액정고 분자에 녹아들어가는 양보다 액정 고분자가 PEEK에 녹아들어가는 양이 더 많음을 알수 있 었다. 고분자-고분자상호작용계수($\chi$12)값은 35$0^{\circ}C$에서 0.069$\pm$0.004이었고, 짝상에서 액정고 분자의 degree of disorder는 PEEK의 질량분율이 증가함에 따라 증가하였다. 블렌드에서 PEEK의 결정화에 액정 고분자는 거의 영향을 주지않았고 액정 고분자의 결정화 역시 PE 따에 영향을 받지 않았다. 모폴로지연구에서는 액정 고분자를 PEEK에 10%첨가시에 PEEK 의 메트릭스상에서 액정 고분자가 신장된 타원형을 형성하였으며 액정 고분자를 20% 첨가 시에는 액정 고분자가 섬유상구조를 가지고 있었다.

• 유변학
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• 제9권4호
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• pp.200-205
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• 1997

등방상에서는 폴리파라페닐렌테레프탈아미드(PPD-T)와 히드록시 프로필 셀룰로오 스(HPC)가 비슷한 유변학적 거동을 보였다. 그러나 이방성에서는 네마틱상을 형성하는 PPD-T와 콜레스테릭상(또는 꼬인 네마틱상)을 형성하는 HPC는 상이한 유변학적 특성을 나타냈다. 이방상을 나타내는 임계농도(C*)이상의 농도에서 Herchel-Bulkey 모델에 의해 얻 어진 항복응력을 보면 HPC의 경우 농도에 관계없이 거의 일정한 값을 나타낸 반면PPD-T 의경우에는 농도증가와 더불어 항북응력값이 크게 증가하였다. 또한 PPD-T가 일\ulcorner거으로 HPC보다 큰값의 항복응력을 나타냈다. 진동수 1 rad/s 에서는 PPD-T와 HPCahen 탄성계 수 G＇/2G＂가 농도의 증가와 더불어 증가하엿다. 그러나 100rad/s 에서는 HPCdmlruddn 임계농도이상의 농도에서 농도증가와 더불어 탄성계수값이 단순감소한 반면 PPD-T의 경우 에는 포화농도(B-point)이상의 농도에서 농도증가와 더불어 탄성계수값이 계속적으로 증가 하였다. HPC의 경우 저장탄성률이 변형정도의 영향을 받지 않았으나 PPD-T의 경우에는 저장탄성률이 변형정도에 매우 민감하였다.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1987년도 학술발표초록집
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• pp.12-12
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• 1987

To improve the fibrillation phenomenon and processibili to of poly(p-phenyleneterephthalamide) (PPD-T) , a P/E copolyamide was prepared by introducing 4,4'-ethylene dianiline (EDA) into rigid chain backbone. The effects of semi-flexible segment on the liquid crystalline properties were investigated. The EDA, used as a comonomer, was prepared by catalylitic reduction of p,p'-dinitrophenyl , obtained by oxidative coupling of p,p'-dinitrotoluene. Various high molecular weight PIE copolyamides were prepared by low temperature solution polycondensation of terephthaloyl chloride (TPC) with various mixtures of p-phenylene diamine (PPD) and EOA. The PfE copolyamides were completely dissolved in 100% svlfuric acid, and the phase transition of P/E copolyamide-sulfuric acid systems was examined in teams of concentration and temperature. Over the chemical compositions, PIE=911, 812, and 713, solutions of anisotropic single phase were acquired. In particular, the two mixing ratios, 911 and 812, gave a good anisotropic spinning dope.

• 한국광학회:학술대회논문집
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• 한국광학회 2001년도 제12회 정기총회 및 01년도 동계학술발표회
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• pp.146-147
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• 2001

Ferro/antiferroelectricty of liquid crystalline phase of bent-core molecules has attracted great attention since the first discovery of antiferroelectric switching in achiral bent-shaped molecules by Watanabe et at. in 1996. This materials show interesting properties usually observed in chiral system, for example, chiral textures, ferro/antiferrroelectricity, strong SHG activity and linear optical activity. (omitted)

• Bulletin of the Korean Chemical Society
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• 제17권11호
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• pp.1004-1009
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• 1996

The interactions between a rod-coil liquid crystalline oligomer, ethyl 4-[4'-oxy-4-biphenylcarbonyloxy]-4'-biphenylcarboxylate with poly(ethylene oxide) (DP=12) (12-4) and LiCF3SO3 have been characterized by using Raman spectroscopy. Band assignments were made comparing the spectrum of 12-4 with those of the poly(ethylene glycol) monomethyl ether(PEGME) (Mw=550) and the ethyl-4'-hydroxybiphenyl-4-carboxylate (EHBPC), which are the coil and mesogen analogues, respectively. Analyzing characteristic bands of the 12-4-salt complex, we have found that the bands belonging to the coil and mesogenic units are changed in both intensities and frequencies. The spectral changes were interpreted from the viewpoint of the complexation between 12-4 and the Li+ ion. However, the possibility that the spectral changes in the mesogenic unit are not due to the complexation with the Li+ ion, but due to the conformational changes by the intercalation of nondissociated LiCF3SO3, is not ruled out.