• 한국고분자학회지:고분자과학과기술
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• 제5권4호
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• pp.353-366
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• 1994

• 한국고분자학회지:고분자과학과기술
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• 제5권3호
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• pp.254-264
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• 1994

• 한국고분자학회지:고분자과학과기술
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• 제2권6호
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• pp.438-452
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• 1991

• 한국산학기술학회논문지
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• 제15권1호
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• pp.575-580
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• 2014

단위체로서 4-[4-(4-hydroxyphenoxy)butoxy]benzoic acid (HBBA)와 p-hydroxy benzoic acid (HBA)를 사용하여 직접 중축합방법에 의해 액정 공중합체를 합성하였다. 합성된 중합체의 구조와 성질은 $^1H$-NMR, FT-IR, DSC, TGA, POM에 의하여 조사되었다. 연구결과에 의하면, 페놀/p-클로로페놀/1,1,2,2-테트라클로로에탄 (25/40/35=w/w/w) 내에서 측정된 중합체의 고유점성도 (${\eta}_{inh}$)는 0.77~1.60 dL/g로 측정되었으며, 중합체 P-80을 제외하고, 공중합체들의 전이온도와 액정상의 범위는 HBA의 양이 증가함에 따라 증가하였다. 중합체의 이러한 특성은 중합체 사슬의 불규칙성과 강직성이 증가하였기 때문으로 생각된다.

• 공업화학
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• 제3권2호
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• pp.280-287
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• 1992

테레프탈산, 비페닐 디카르복시산과 히드로퀴논을 용액중합하여 전방향족 액정 폴리에스테르를 합성하고 테레프탈산과 비페닐 디카복시산의 몰비가 액정중합체의 열적성질, 열안정성 및 메소상의 구조에 미치는 영향을 DSC, TGA, 편광현미경 및 X선회절기로 조사하였다. 본 연구에서 합성한 중합체는 모두 열방성 액정중합체였고 네마틱 액정상을 나타내었으며, 용융온도 및 등방화온도는 중합체중의 비페닐렌구조가 증가함에 따라 약간씩 증가하였다. 또한 중합체의 열안정성은 중합체중의 비페닐렌구조가 증가함에 따라 개선되었으며, 비페닐렌구조를 가지는 중합체의 결정도는 상당히 높아서 약 33%정도로 나타났다.

• 한국염색가공학회지
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• 제7권4호
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• pp.8-15
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• 1995

A series of thermotropic Polyurethanes mesogenic unit were synthesized by polyaddition of a para-type diisocyanate such as 2,5-tolylene diisocyanate(2,5-TDI) with 4-4'-bis($\omega$-hydroxyalkoxy) biphenls(BPm: $HOCmH_{2m}OC_{6}H_{4}OC_{m}H_{2m}OH$ : m is the carbon number of the hydroxyalkoxy group) in DMF. Intrinsic viscosities of the polymers were in the range of 0.41~0.99dL/g DSC thermograms for these polymers exhibited two endothermic peaks corresponding to phase transitions of melting and isotropization. For examplem polyurethane 2,5-TDI/BPll with [η]=0.99 prepared from 2.5-TDI and 4,4'-bis[11-hydroxyundecaoxy biphenyl(BP11) a liquid crystalline phase from 156 to 173$^{\circ}C$. The thermotropic properites of liquid crystalline polyurethanes have been investigated by wide-angle X-ray scatter(WAXS), infrared (IR) spectroscopy, and differential scanning calorimetry (DSC). The mesomorphic behavior of the polyurethanes was concluded to be greatly dependent on the intermolecular hydrogen bonds through the urethane.

• Fibers and Polymers
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• 제2권2호
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• pp.86-91
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• 2001

Liquid crystalline (LC) poly(ethylene terephthalate-co-2(3)-chloro-1,4-phenylene terephthalate) [copoly(ET/CPT)] was prepared using poly(ethylene terephthalate) (PET) as a flexible spacer, terephthalic acid (TPA), and chlorohydroquinone diacetate (CHQDA). All reactions involved in the copolymerization were investigated using some model compounds: TAP was used for acidolysis, diphenylethyl terephthalate (DPET) for interchange reaction between PET chains, and 야-o-chlorophenyl terephthalate (DOCT) and di-m-chlorophenyl terephthalate (DMCT) for interchange reaction between PET and rigid rodlike segments. Activation energies obtained for the acidolysis of PET with TPA and for interchange reaction of PET with DPET, DOCT, and DMCT were 19.8 kcal/mol, 26.5 kcal/mole, and 45.9 kcal/mole, respectively. This result supports that the copolymerization proceeds through the acidolysis of PET with TPA first and subsequent polycondensation between carboxyl end group and CHQDA or acetyl end group, which is formed from the reaction of CHQDA and TPA. Also, it was found that ester-interchange reaction can be influenced by the steric hindrance. Copoly(ET/CPT)s obtained has ethylene acetate end groups formed from acetic acid hydroxy ethylene end groups and showed almost the random sequence distribution for all compositions.

• Macromolecular Research
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• 제13권1호
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• pp.19-29
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• 2005

Polymer composites based on a thermotropic liquid-crystalline polymer (TLCP) and poly(butylene terephthalate) (PBT) were prepared using a melt blending process. Polymer composites consisting of bulk cheap polyester with a small quantity of expensive TLCP are of interest from a commercial perspective. The interactions between the PBT chains and the flexible poly(ethylene terephthalate) (PET) units in the TLCP phase resulted in an improvement in the compatibility of PBT/TLCP composites. TLCP droplets deformed and fragmented into smaller droplets in the PBT/TLCP composites, which resulted in TLCP fibrillation through the effective deformation of the TLCP droplets. The nucleation activities of the PBT/TLCP composites increased by adding even a small amount of the TLCP component.

• Elastomers and Composites
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• 제41권2호
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• pp.108-115
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• 2006

비페닐기를 함유하는 새로운 형태의 액정성 폴리우레탄을 신규로 합성한 4,4'-Bis(9-hydroxynonoxy)biphenyl (BP9)와 2,6-tolylene diisocyanate, 2,5-tolylene diisocyanate, 2,4-tolylene diisocyanate, 1,4-phenylene diisocyanate 및 hexamethylene diisocyanate의 중부가 반응에 의해 합성하였다. 단량체 BP9은 스멕틱상을 형성하였으며 1,4-PDI/BP9을 제외한 나머지 폴리우레탄에서는 모두 액정성을 나타내었다. 합성된 단량체와 중합체들의 구조는 적외선분광분석기 및 핵자기공명분석기를 사용하여 확인하였으며, 그들의 열적 상전이 온도 및 안정성들은 시차주사 열량분석기와 편광현미경으로 조사하였다.

• Macromolecular Research
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• 제14권3호
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• pp.261-266
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• 2006

Blends of silicone rubber (VMQ) and liquid crystalline polymer (LCP) were prepared using a melt blending technique in the presence and absence of glass fiber and coupling agents. The effect of glass fiber and coupling agents on the thermal, dynamic mechanical, morphological pro-perties and cure characteristics of VMQ/LCP blends were studied. The vinyl silane coupling agent showed a significant effect on the above mentioned properties of VMQ/LCP blends by reacting at the interface between VMQ and LCP. The viscosity of the VMQ/LCP blends decreased with the addition of a coupling agent. A substantial improvement in storage modulus of VMQ/LCP blends was observed in the presence of glass fiber and coupling agents. However, as a coupling agent vinyl silane proved to be better than amine for the VMQ/LCP-glass-containing blends. The thermal stability of the pure silicone rubber was higher than those of the blends. This high thermal stability of silicone rubber was attributed to the Si-O-Si bonds. However, the thermal stability of the blends decreased further in the presence of a coupling agent, possibly due to a decrease in blend crystallinity.