• Polymer(Korea)
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• v.36 no.4
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• pp.413-419
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• 2012

Multi-functional urethane acrylate monomers as the curing agent of poly(phenylene ether) (PPE) were synthesized and then the urethane bond formation was checked by FTIR spectrometry and NMR analysis. The synthesized monomers were mixed with PPE and fabricated to dielectric substrates. After forming PPE/monomer composite sheets by a film coater, several sheets were laminated to a test substrate in a vacuum laminator and then its properties depending on the type and the amount of monomers, such as dielectric constant, dielectric loss, and peel strength, were measured. Between the two different hydroxyl acrylates, when the monomer synthesized with 2-hydroxy-3-phenoxypropyl acrylate containing a phenyl group was used as a curing agent, a smaller dielectric loss was obtained and the dielectric constant and loss decreased with a decrease in the amount of the monomer. The peel strength values of the test substrates, however, did not show any specific difference between the cases of two synthesized monomers. As a result, it was obtained the polymer substrate for high frequency application having peel strength of about 10 N, low dielectric constant of 2.54, and low dielectric loss of 0.0027 at 1 GHz.

• Polymer(Korea)
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• v.38 no.1
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• pp.38-42
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• 2014

The poly[(9,9-bis((6'-(N,N,N-trimethylammonium)hexyl)-2,7-fluorene)-alt-(9,9-bis(2-(2-(2-methoxyethoxy)ethoxy)ethyl)-9-fluorene)) dibromide (WPF-6-oxy-F)] and graphene oxide (GO) was blended and irradiated with gamma ray under ambient condition. This WPF-6-oxy-F-GO composite was investigated as a hole-transporting layer (HTL) in organic solar cells (OSCs). Compared with the pristine GO, the sheet resistance ($R_{sheet}$) of irradiated WPF-6-oxy-F-GO was decreased about 2 orders of magnitude. The reason for the decrease of $R_{sheet}$ is the effect of efficient ${\pi}-{\pi}$ packing resulted from the formation of C-N bond between WPF6-oxy-F and GO. As a result, the efficiency of OSCs was dramatically enhanced ~ 6.10% by introducing irradiated WPF-6-oxy-F-GO as a HTL. WPF-6-oxy-F-GO is a sufficient candidate for HTL to facilitate the low-cost and high efficiency OSCs.

• Polymer(Korea)
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• v.33 no.4
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• pp.358-363
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• 2009

Maleic anhydride-grafted polypropylene has been widely used to improve the interfacial interaction between the components in PP/polar polymer blends and PP/filler composites and to maximize the physical properties and thermal properties. In this paper. the maleic anhydride (MAH)-grafted polypropylene (co-PP) was fabricated through reactive extrusion process with di-cumyl peroxide (DCP) as an initiator. The grafting degree of MAH depending on the contents of DCP and MAH was investigated by FT-IR spectra and chemical titration. The grafting degree increased with increasing MAH concentration and also showed maximum value at 0.06 wt% of DCP concentration. Melt flow index (MFI) of the grafted copolymer was increased with increasing the contents of MAH. The DSC and TGA analysis data indicate the melting temperature and thermal degradation of PP depending on the grafting degree of MAH.

• Journal of the Korean Electrochemical Society
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• v.25 no.3
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• pp.105-112
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• 2022

For the commercialization of all-solid-state batteries, it is essential to develop a solid electrolyte that can be operable at room temperature, and it is necessary to manufacture all-solid-state batteries by adopting materials with high ionic conductivity. Therefore, in order to increase the ionic conductivity of the existing oxide-based solid, Li₇La₃Zr₂O₁₂ (LLZO) doped with heterogeneous elements was used as a filler material (Al and Nb-LLZO). An electrolyte with garnet-type inorganic filler doped was prepared. The binary metal element and the polymer mixture of poly(ethylene oxide)/poly(propylene carbonate) (PEO/PPC) (1:1) are uniformly manufactured at a ratio of 1:2.4, The electrochemical performance was tested at room temperature and 60 ℃ to verify room temperature operability of the all-solid-state battery. The prepared composite electrolyte shows improved ionic conductivity derived from co-doping of the binary elements, and the PPC helps to improve the ionic conductivity, thereby increasing the capacity of all-solid-state batteries at room temperature as well as 60 ℃. It was confirmed that the capacity retention rate was improved.

• Journal of Adhesion and Interface
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• v.22 no.4
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• pp.136-143
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• 2021

Polyurea has been investigated as a polymer matrix for composite materials because of its high mechanical strength. Although polyurea has a similar chemical structure to polyurethane, it has much higher strength and durability. In this study, the fabrication of polyurea composites reinforced with carbon nanotube (CNT) and graphene oxide (GO) is demonstrated to enhance the tensile strength of the glass fibers composite. Using FTIR and Raman spectroscopies, the chemical structures of polyurea, CNT, and GO are investigated. As a result, spectroscopy analysis reveals that the chemical structure of CNT, GO, and polyurea is maintained during the fabrication of the composite structure. Scanning electron microscopy reveals the uniform distribution of CNT and GO across the polyurea matrix. The reinforcement of 1 wt% CNT in polyurea enhances the tensile strength of CNT/polyurea composites. In contrast, the reinforcement of GO in polyurea induces the degradation of the tensile strength of GO/polyurea composites.

• Composites Research
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• v.31 no.4
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• pp.122-127
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• 2018

Sandwich composites of carbon fiber reinforced plastic(CFRP) and polymer foam will be used to automobile and aerospace industry according to increasing importance of light weight. In this study, mechanical and heat resistance properties of sandwich composites were compared with type of polymer foam (polyethylene terephthalate(PET), polyvinylchloride(PVC), epoxy and polyurethane). All types of polymer foams were degraded to 30, 60, 120, 180 minutes in $180^{\circ}C$. After heat degradation, the polymer foams were observed using optical microscope and compressive test was performed using universal testing machine(UTM). Epoxy foam had the highest compressive property to 2.6 MPa and after thermal degradation, the mechanical property and structure of foam were less changed than others. Epoxy foam had better mechanical properties than other polymer foams under high temperature. Because the epoxy foam was post cured under high temperature. As the results, Epoxy foam was optimal materials to apply to structures that thermal energy was loaded constantly.

• Polymer(Korea)
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• v.29 no.2
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• pp.204-210
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• 2005

We describe a colorless, transparent polyimide films for plastic display substrate which should have heat resistance, roll-to-roll processability and low CTE (coefficient of thermal expansion) property. Colorless polyimides were synthesized from 3,3',4,4'-oxydiphthalic anhydride (ODPA) 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and diamines such as sulfonyldianiline, aminophenoxybenzene (TPE-p, TPE-q, TPE-r) and bis[4-(3-aminophen oxy)phenyl] sulfone (m-BAPS). Their optical properties were measured by UV spectrophotometer, colormeter and hazemeter. We prepared polyimide/organophilic layered silicate nanocomposite to improve dimension stability. These colorless polyimide films showed UV transmittance by the level upper $89\%$, at 440 nm and excellent optical property having the value under yellow index (YI)=7. In addition, polyimide nanocomposite films also showed an improvement of CTE value as decreased according to the amount of layered silicate contents.

• Journal of the Korean Applied Science and Technology
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• v.35 no.3
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• pp.595-605
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• 2018

In recent years, researches on organic-inorganic coating films have conducted a nanocomposite system composed of organic resin matrices having excellent flexibility and chemical stability and inorganic materials having excellent mechanical properties. The o-phenylphenoxyethyl acrylate (OPPEA) used as the acrylate monomer has a high refractive index of 1.58, and the bisphenol A ethoxylate diacrylate (BAEDA) has a low refractive index but improves the chemical stability of the organic resin. In addition, zirconia used as an inorganic material exhibits excellent durability and optical properties. In this study, the BAEDA contents in acrylate monomer were controlled to produce a film with suitable optical transparency. And optimum conditions were established by comparing the changes in surface properties of PET films detected with pencil hardness tester, Abbe's refractometer, and UV-vis spectrophotometer. The hydrophobicity and the dispersibility of zirconia in acrylate monomer were much improved after modification with ${\gamma}$-methacryloxypropyltrimethoxysilane (MPS), which is a silane coupling agent. And the existence of ester C=O bond peak at $1716cm^{-1}$ introduced by MPS through FT-IR ATR spectrophotometer confirmed the completion of surface modification of zirconia with MPS. In addition, the presence of silicon atom on the surface modified zirconia was also proved using X-ray fluorescence spectrometer. When the photocurable hybrid coating was prepared by introducing chemically modified zirconia into acrylate monomer, the refractive index of this coated PET film was improved by 1.2%, compared to the only acrylate coated PET film. The homogeneous distribution of zirconia in acrylate coating layer on PET film was also identified through SEM/EDS mapping analysis technique.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.99-99
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• 2011

최근 건강에 대한 관심이 높아지면서 천연 기능물질을 이용한 고기능 및 고부가가치 상품개발이 여러 산업분야에서 일반화되는 추세이다. 대표적으로 마이크로캡슐은 원하는 기능을 발휘할 수 있는 기능성 물질을 다양한 방법으로 다양한 제품에 부여함으로써, 기능성 물질을 오랜 기간 동안 외부로 방출하거나 외부의 환경으로부터 보호하는 수단으로 각광받고 있다. 이러한 마이크로캡슐은 의약분야 제초제, 멸충제, 곰팡이 방지제, 살균제로 적용되는 농약분야, 식품 분야, 화장품 분야 등의 전반에 걸쳐 응용 및 연구가 활발히 이루어지고 있다. 이에 본 연구에서는 다양한 나노 합성기술과 유/무기 하이브리드를 이용해 서방화 관련 기술을 개발하여 보습성, 항균, 노화방지, 외부 유해물질로부터의 피부보호 특성을 가진 인체 친화형 복합기능성 섬유 가공조제를 개발하여 다양한 섬유소재에 적용하고자 하며, 궁극적으로 기존 선진국 제품의 기능을 뛰어넘는 원천기술, 즉 새로운 가공제 합성과 응용성, 그 성능평가와 동시에 최적의 처리기술을 개발함으로써 섬유제품의 부가가치를 높이는 계기를 마련하고자 한다. 본 연구에서는 나노미터 직경을 갖는 침상형의 주형(hydroxyapatite)을 이용하여 중공 나노구조체를 제조 한 후 이에 천연고분자를 혼합하여 초음파처리 후 유/무기 하이브리드 기술을 이용한 서방성 가공제를 합성하였다. 중공의 나노구조체 확인은 투과전자현미경(TEM)을 이용하였으며, 주형의 나노구조체는 주사전자현미경(FE-SEM)으로 확인하였다. 이상의 결과를 통해 본 연구에서 제안한 방법이 나노구조체의 새로운 합성방법으로써 가능성을 확인할 수 있었다.

• Journal of Adhesion and Interface
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• v.14 no.1
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• pp.36-42
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• 2013

To improve hydrolytic stability of polyurethane (PU) adhesives, a silane coupling agent (SCA) was added. 3-Isocyanatopropyl triethoxy silane (ITS) as a SCA has two functional groups in the main chain and it is used to improve an interfacial interaction between polymer and inorganic material or metal. In this study, PU adhesives with different amounts of ITS from 0 to 1 wt% were synthesized. Pot time, modulus, thermal stablilty, and adhesive force of the obtained samples were measured. The results showed that the adhesives with ITS showed better properties than that of pure one.