• Title, Summary, Keyword: liquid crystalline epoxy

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Thermal Decomposition Behavior of Liquid Crystalline Epoxy-Based Composites (열경화성 액정 에폭시 매트릭스 복합재료의 열분해 거동 비교)

  • Park, Jonghyun;Cho, Seung Hyun
    • Textile Science and Engineering
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    • v.55 no.5
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    • pp.324-329
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    • 2018
  • Thermosetting liquid crystalline epoxy is an epoxy polymer that forms a liquid crystalline network structure upon curing. 4,4'-Diglycidyloxybiphenyl with an aromatic rigid-rod part such as a biphenyl group exhibits liquid crystallinity. Biphenol epoxy resin (BP), which is cured by using sulfanilamide, forms a liquid crystalline network by reacting the amine and epoxy ring of sulfanilamide and biphenol. In this experiment, silicon nitride (Si3N4) or aluminum nitride (AlN) was used as a filler. The activation energy required for the decomposition was calculated using the Kissinger method and the Flynn-wall method to confirm the thermal properties of the thermosetting liquid crystalline epoxy with silicon nitride. As a result, the activation energy required for decomposition of the composite increased with increasing silicon nitride content, and it was confirmed that silicon nitride increased the thermal stability of the thermosetting liquid crystalline epoxy.

Thermal Decomposition Activation Energy of Liquid Crystalline Epoxy Composite with Zirconia Filler (지르코니아를 함유한 열경화성 액정 에폭시의 열분해 활성화 에너지)

  • Moon, Hee Jung;Kim, Kyung Ho;Hwangbo, Sejin;Cho, Seung Hyun
    • Textile Science and Engineering
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    • v.52 no.3
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    • pp.206-214
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    • 2015
  • A liquid crystalline thermosetting epoxy 4,4'-diglycidyloxy-${\alpha}$-methylstilbene (DOMS) was synthesized using sulfanilamide as the curing agent. To heat cure the epoxy, filler contents of 0.5-5 wt% zirconia were used. Thermogravimetric analysis was performed, and the activation energy was calculated using the Kissinger and Flynn-Wall methods. The activation energy was proportional to the amount of zirconia used. As the activation energies needed for 1% and 10% decomposition were similar, the thermal decomposition was predicted to have the same mechanism.

Thermal Decomposition Activation Energy according to the Mesogen Structure of Liquid Crystalline Epoxy Composite with Aluminum Oxide Filler (산화 알루미늄을 분산시킨 열경화성 액정 에폭시의 Mesogen 구조에 따른 열분해 활성화 에너지)

  • Hyun, Ha Neul;Cho, Seung Hyun
    • Textile Science and Engineering
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    • v.56 no.5
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    • pp.314-320
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    • 2019
  • A liquid crystalline thermosetting-epoxy-based composite was fabricated using diglycidyl ether of 4,4'-bisphenol and diglycidyl ether of terephthalylidene-bis-(4-amino-3-methylphenol), with aluminum oxide as a filler, and sulfanilamide and 4,4'-diaminodiphenylethane as a curing agent. Thermogravimetric analysis was performed to investigate its thermal behavior, and temperature differences of the sample were recorded using 1.0-7.0 wt% aluminum oxide. The activation energy for thermal decomposition was calculated using the Kissinger method, and the Flynn-Wall method. The results showed that the activation energy was proportional to the amount of filler added.

Research of Thermal Properties for Liquid Crystalline Epoxy Composites with Tin Oxide Filler (산화주석을 함유한 열경화성 액정 에폭시의 열적 특성에 관한 연구)

  • Hyun, Ha Nuel;Cho, Seung Hyun
    • Composites Research
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    • v.33 no.1
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    • pp.25-29
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    • 2020
  • A liquid crystalline thermosetting-epoxy-based composite was fabricated using diglycidyl ether of 4,4'-biphenol, tin(IV) oxide as a filler, and sulfanilamide as a curing agent. To investigate the thermal behavior, Thermogravimetric Analysis and Laser Flash Apparatus were performed using 3.0-7.0 wt% Tin(IV) oxide. The result showed that the activation energy and thermal conductivity were proportional to the amount of added filler.

Microstructural Morphology of Molded Thin Composites of Thermotropic Liquid Crystalline Polymer and Polyamide 6 (서모트로픽 액정폴리머와 폴리아미드6으로 성형된 얇은 복합재료의 미세구조형태)

  • Choe, Nak-Sam;Choe, Gi-Yeong;Ha, Seong-Gyu
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.7
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    • pp.1703-1711
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    • 2000
  • Microstructural morphology of molded composites of thermotropic liquid crystalline polymer(LCP) and polyamide 6 (PA6) has been studied as a function of epoxy fraction. Injection-moulding of a thin composite plaque at a temperature below the melting point of the LCP fibrils by suing the extruded LCP/PA6 pellets produced multi-layered structures: 1) the surface skin layer with thickness of 65-120 ym exhibiting a transverse orientation, 2) the sub-skin layer with an orientation perpendicular to the surface skin, i.e. in the flow direction, 3) the core layer with arc-curved flow patterns. Similar microstructural orientations were observed in the respective layers for the composite plaques with different fractions of epoxy.

Development of Epoxy Composites with SWCNT for Highly Thermal Conductivity (고방열 재료 개발을 위한 에폭시/단일벽 탄소나노튜브 복합체 개발)

  • Kim, Hyeonil;Ko, Heung Cho;You, Nam-Ho
    • Composites Research
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    • v.33 no.1
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    • pp.7-12
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    • 2020
  • Over the past decade, liquid crystalline epoxy (LCER) has attracted much attention as a promising matrix for the development of efficient heat dissipation materials. This study presents a comprehensive study including synthesis, preparation and chacterization of polymer/inorganic composites using typical 4,4-diglycidyloxybiphenyl (DP) epoxy among LECR. To confirm the thermal conductivity of composite materials, we have prepared composite samples composed of epoxy resin and single-wall carbon nanotube (SWCNT) as a filler. In particular, DP composites exhibit higher thermal conductivity than commercial epoxy composites that use the same type of filler due to the highly ordered microstructure of the LCER. In addition, the thermal conductivity of the DP composite can be controlled by controlling the amount of filler. In particular, the DP composite containing a SWCNT content of 50 wt% has the highest thermal conductivity of 2.008 W/mK.

Fabrication of a microlens array using a birefringent layer and ferroelectric liquid crystal

  • Lee, Yong-Min;Lee, Kwang-Ho;Choi, Yoon-Seuk;Kim, Jae-Hoon
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.109-112
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    • 2007
  • A new concept of the microlens array is fabricated using a birefringent layer on the concave microlens array. The stacked layers of liquid crystalline polymer (LCP) and the UV epoxy focus an incident light due to the surface relief structure. The ferroelectric liquid crystal layer was added to control the focusing intensity with a fast switching time.

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Development of Highly Thermal Conductive Liquid Crystalline Epoxy Resins Bearing Phenylcyclohexyl Mesogenic Moieties (Phenylcyclohexyl mesogenic moieties를 함유한 고 열전도성 액정성 에폭시 수지의 개발)

  • Jeong, Iseul;Kim, Youngsu;Goh, Munju
    • Composites Research
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    • v.30 no.6
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    • pp.350-355
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    • 2017
  • The new liquid crystalline (LC) epoxy was designed by substituting the phenylcyclohexyl (PCH) mesogen moiety with an alkyl chain at the 2,5 position of the diglycidyl terephthalate. The mesomorphic properties were evaluated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). All LC epoxy derivatives exhibited an enantiotropic smectic phase upon heating and cooling process. The LC phase temperature range was widened by mixing the eutectic mixture of LC epoxies. Interestingly, the cured LC epoxy exhibited the highest thermal conductivity of $0.4W{\cdot}m^{-1}{\cdot}K^{-1}$. The novel LC epoxy with high thermal conductivity might be used as a composite material for electronic and display devices.

Development of Highly Thermal Conductive Liquid Crystalline Epoxy Resins for High Thermal Dissipation Composites (고방열 복합소재 개발을 위한 고열전도성 액정성 에폭시 수지의 개발)

  • Kim, Youngsu;Jung, Jin;Yeo, Hyeonuk;You, Nam-Ho;Jang, Se Gyu;Ahn, Seakhoon;Lee, Seung Hee;Goh, Munju
    • Composites Research
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    • v.30 no.1
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    • pp.1-6
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    • 2017
  • Epoxy resin (EP) is one of the most famous thermoset materials. In general, because EP has three-dimensional random network, it possesses thermal properties like a typical heat insulator. Recently, there has been increasing interest in controlling the network structure for making new functionality from EP. Indeed, the new modified EP represented as liquid crystalline epoxy (LCE) is spotlighted as an enabling technology for producing novel functionalities, which cannot be obtained from the conventional EPs, by replacing the random network structure to oriented one. In this paper, we review current progress in the field of LCEs and their application for the highly thermal conductive composite materials.