• 제목/요약/키워드: Liquid crystalline polymer

검색결과 179건 처리시간 0.026초

Thermotropic Liquid Crystal Polymer Reinforced Poly(butylene terephthalate) Composites to Improve Heat Distortion Temperature and Mechanical Properties

  • Kim, Jun-Young;Kang, Seong-Wook;Kim, Seong-Hun
    • Fibers and Polymers
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    • 제7권4호
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    • pp.358-366
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    • 2006
  • Thermotropic liquid crystal polymer (TLCP)-reinforced poly(butylene terephthalate) (PBT) composites were prepared by melt processing. The improvement in the mechanical properties and the processability of the PBT/TLCP composites was attributed to the reinforcing effect by TLCP phase and its well distribution in the PBT matrix. X-ray diffraction results demonstrated that a slow cooling process leads to the thicker lamellar structures and the formation of more regular crystallites in the composites. The incorporation of TLCP improves not only the tensile strength and flexural modulus but also the heat distortion temperature (HDT) of the PBT/TLCP composites. The HDT values of the composites were dependent on TLCP content. The improvement in the HDT values of the PBT/TLCP composites may be explained in terms with the increased flexural modulus, the development of more regular crystalline structures, and the enhancement of the ability of the composites to sustain the storage modulus by TLCP phase. In addition, the simple additivity rule makes it possible to predict the HDT values of the PBT/TLCP composites.

High Out-of-Plane Alignment of Liquid Crystalline Methacrylate Copolymer Bearing Photoreactive 4-Styrylpyridine Moiety

  • Kwak, Gi-Seop;Kong, Jong-Yun;Kim, Min-Woo;Hyun, Seok-Hee;Kim, Woo-Sik
    • Macromolecular Research
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    • 제17권4호
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    • pp.271-275
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    • 2009
  • This paper describes the out-of-plane order of a liquid crystalline(LC) methacrylate copolymer(3) comprised of a methacrylate(1) with a 4-styrylpyridine moiety as the photo-cyclodimerizable group and a benzoate moiety as the mesogenic group in the side chain, and another methacrylate(2) with a 4-(4-methoxyphenyl)benzoate moiety as the mesogenic group. The composition of 1 and 2 units in 3 was estimated to have a molar ratio of 54.2:45.8 by $^{1}H$ NMR spectroscopy. The X-ray diffraction study revealed that the copolymer forms a partial bilayer smectic structure. The copolymer gave rise to a high out-of-plane order parameter of about 0.74 in a wide LC temperature range of $110{\sim}160^{\circ}C$ after linearly polarized, UV light irradiation and subsequent annealing. Moreover, the external reflection IR analysis indicated that excess UV-light irradiation makes the out-of-plane LC structure of the copolymer appear in a higher and wider temperature range.

폴리프로필렌/열방성 액정 고분자 블렌드의 상용화에 관한 연구 (Study on a compatibilization of polypropylene/thermotropic liquid crystalline polymer blends)

  • 손영곤
    • 한국산학기술학회논문지
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    • 제8권5호
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    • pp.1215-1219
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    • 2007
  • 이 논문에서는 폴리프로필렌/열방성 액정고분자 블렌드에 관한 연구 결과를 나타냈다. 기존의 연구에서 주로 쓰인 액정고분자 (Thermotropic Liquid Crystalline Polymer, TLCP)는 용융점이 대부분 270o0 이상으로 가공은 적어도 300oC 이상에서 가능하기 때문에, PP와의 블렌드 시 PP의 열분해를 피할 수 없다. 이 때문에 원하는 정도의 물성을 얻기 위해서는 과량의 TLCP를 첨가하여야 한다. 이 연구에서 고온용 TLCP 대신 융점이 220oC 정도 되는 새로운 TLCP를 사용하여 블렌드를 제조하였고, 그 특성을 관찰하였다. 연구 결과 기존 PP/TLCP 블렌드와 비교해 동등 이상의 물성을 보임을 관찰할 수 있었고, 이로서 새로운 저온용 TLCP가 PP의 강화제로 사용될 수 있음을 알 수 있었다.

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Polymer blends with a liquid crystalline polymer dispersed phase

  • Lee, Heon-Sang;Morton M. Denn
    • 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.

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Structures and Physical Properties of in situ composite based on Liquid Crystalline Polymer and Poly(ethylene 2,6-naphthalate) Blends

  • Yoo, Hyun-Oh;Kim, Seong-Hun;Hong, Soon-Man;Hwang, Seung-Sang
    • 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)

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Poly과 열방성액정 고분자 블렌드의 열적 성질에관한연구 (Thermal Properties of blends of Poly and a Thermotropic Liquid Crystalline Polymer)

  • 김명섭
    • 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.

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변형 Halpin-Tsai식에 의한 PHB/PEN/PET 섬유의 탄성률 예측 (Determination of Tensile Modulus of PHB/PEN/PET Fiber Using Modified Halpin-Tsai Equation)

  • 정봉재;김성훈;이승구;전한용
    • 폴리머
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    • 제24권6호
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    • pp.810-819
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    • 2000
  • Poly(p-hydroxybenzoate) (PHB)/poly(ethylene terephthalate) (PET) 8/2 공중합 폴리에스터 액정고분자와 poly(ethylene 2,6-naphthalate) (PEN), PET를 용융방사하여 인장탄성률을 측정하고, 55$^{\circ}C$ ο-chlorophenol 에서 2시간 동안 모재인 PEN/PET부분을 용출시킨 후, 용출되지 않은 PHB 피브릴을 전자현미경으로 조사하였다. 모재고분자 속에 존재하는 피브릴이 단섬유일 때 적용하는 Halpin-Tsai식과 피브릴이 연속상일 경우 적용하는 혼합의 법칙을 사용하여 이론적인 탄성률을 계산하고, 측정된 탄성률과 비교하였다. 이론적 탄성률과 측정된 탄성률의 차이를 보정하기 위하여 무차원 점도비 상수 (K)를 정의하고, K를 적용하여 기존의 식을 변형하였다. 변형된 Halpin-Tsai식과 혼합의 법칙을 통해 계산된 이론적인 탄성률은 용융방사를 통해 제조된 복합재료의 탄성률 계산에 더 적합함을 확인하였다.

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Preparation of Smectic Layered Polymer Networks Using Side Chain Liquid Crystalline Polymers Having Latent Reactive Monomeric Units

  • Oh, Young-Taek;Kim, Woo-Jin;Seo, Sang-Hyuk;Chang, Ji-Young
    • Macromolecular Research
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    • 제17권2호
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    • pp.84-90
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    • 2009
  • We prepared side-chain liquid crystalline polymers comprising two monomeric units, one having a mesogenic side group that could form a smectic mesophase and the other having a phenolic group attached to the polymer backbone via a thermally reversible urethane bond. The urethane linkage between the isocyanate and phenol groups was stable at room temperature, but it cleaved to generate an isocyanate group when the temperature was increased. When annealed, the copolymers in their smectic mesophases became insoluble in common organic solvents, suggesting the formation of network structures. XRD analysis showed that the annealed polymers maintained their smectic LC structures. The crosslinking process probably proceeded via the reaction of the dissociated isocyanate groups. Some of the isocyanate groups would have first reacted with moisture in the atmosphere to yield amino groups, which underwent further reaction with other isocyanate groups, resulting in the formation of urea bonds. We presume that only polymer chains in the same layer were crosslinked by the reaction of the isocyanate groups, resulting in the formation of a layered polymer network structure. Reactions between the layers did not occur because of the wide layer spacing.

Electro-Optical Properties of Polyoxetane based Liquid Crystalline Polymer/Low Molecular Weight Liquid Crystal

  • Jang, Chi-Woong;Kwon, Oh-Jeong;Kim, Ku-Nam;Kwon, Young-Wan;Lim, Tong-Kun;Jin, Jung-Il
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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    • pp.482-483
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    • 2003
  • We have synthesized a new material of polyoxetane based liquid crystalline polymer/liquid crystal (LCP/LC) for flexible memory or dynamic mode device and characterized the electro-optics behavior of this system. The microscopic dynamic behavior of main chain, side chain, and the low molecular weight LC were characterized by X-ray scattering and time resolved FTIR..

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