• Applied Chemistry for Engineering
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• v.25 no.2
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• pp.121-133
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• 2014

Block copolymers including ABA triblock architectures are useful as thermoplastic elastomers and toughened plastics depending on the relative glassy and rubbery content. These materials can be blended with other polymers and utilized as additives, toughening agents, and compatibilizers. Most of commercially available block copolymers are derived from petroleum. Renewable alternatives are attractive considering the finite supply of fossil resources on earth and the overall economic and environmental expenses involved in the recovery and use of oil. Furthermore, tomorrow's sustainable materials are demanding the design and implementation with programmed end-of-life. The present review focuses on the preparation and evaluation of new classes of renewable ABA triblock copolymers and also emphasizes on the use of carbohydrate-derived poly(lactide) or plant-based poly(olefins) having a high glass transition temperature and/or high melting temperature for the hard phase in addition to the use of bio-based amorphous hydrocarbon polymers with a low glass transition temperature for the soft components. The combination of multiple controlled polymerizations has proven to be a powerful approach. Precision-controlled synthesis of these hybrid macromolecules has led to the development of new elastomers and tough plastics offering renewability, biodegradability, and high performance.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.10a
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• pp.61-64
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• 1997

1. 서론 : 적절한 이산화탄소의 분리는 지구온난화의 가속현상을 늦출 수 있을 뿐만 아니라 각종 탄화수소가스의 원료로 분리 정제된 이산화탄소를 재이용할 수 있으므로 경제적으로 매우 중요하다. 이산화탄소 분리에 사용되던 기존 공정들의 단점을 보완할 수 있는 대체방안으로 최근에 개발되기 시작한 것이 소수성의 다공성 고분자 분리막(hydrophobic porous ploymeric membrane) 방법인데, 이는 모듈의 유효 막 표면적이 상대적으로 크고 기체와 액체의 흐름을 독립적으로 제어할 수 있으므로 범람 등의 현상이 없으나 막 자체의 저항이 비교적 큰 단점을 가지고 있다. Qi와 Cussler는 이러한 특성을 가지는 중공사막 모듈에서의 기-액 흐름에 대한 물질전달 상관관계식을 얻었으며[1], Karoor 등은 여러 가지 중공사막 모듈을 사용하여 순수물과 diethanolamine(DEA) 등의 흡수제에 대한 이산화탄소의 물질전달 거동을 수치모델과 실험을 통하여 고찰하였다[3]. 또한 중공사막 접촉기의 실제적 응용에 대하여 Matsumoto 등은 화력발전소에서 발생하는 연소가스 내의 이산화탄소 흠수에 대한 연구를 수행하였다[4]. 본 연구에서는 중공사막 접촉장치를 사용하여 흡수제를 순수물과 탄산칼륨($K_2CO_3$)을 사용했을 경우의 이산화탄소의 분리 거동을 수치모델과 실험을 통하여 고찰하였다. 수치모델의 경우 이전까지의 연구가 반응이 없는 경우나 반응식을 간략화시킨 경우에 한정되었는데 비하여, 반으이 있는 경우 각각의 반응물질들의 거동을 고려한 반응식을 유도하여 해를 구하고자 하녔다.

• Composites Research
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• v.32 no.3
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• pp.127-133
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• 2019

Although carbon nanotubes(CNTs) have outstanding theoretical mechanical and electrical properties, CNT fibers(CNTFs) have not yet reached that level. Particularly, tensile strength is only about 10% or less, so studies for making up for it are being actively conducted. As a way for improving mechanical strength, methods such as synthesizing long CNT, orientation, chemical cross-linking, hydrogen bonding and polymer infiltration are being studied. In this review paper, we report preparation methods for highly conductive and strong CNTF/Carbon composites through coating and infiltration followed by carbonization of carbon precursor polymers such as polyacrylonitrile (PAN) and polydopamine (PDA) on CNTFs.

• Polymer(Korea)
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• v.26 no.1
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• pp.9-17
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• 2002

The free radical bulk copolymerizations of perfluoroalkylethyl acrylate(FA) containing perfluoro group ($CF_3(CF_2)_nCH_2CH_2$-; n=5, 7, 9, 11) with styrene were conducted at $60^{\circ}C$ using AIBN as an initiator. Reactivity ratios($r_1$, $r_2$) were determined from monomer feed compositions and the NMR spectroscopically measured copolymer compositions using Kelen-Tudos method. The structures of copolymers were characterized with FT-IR and $^1H-NMR$ analysis. Their thermal properties investigated with DSC and TGA were decreased with increasing the content of fluorinated acrylate in the copolymer. Their surface free energies were calculated with measuring contact angles of the copolymers and PMMA blends with a small amount of them.

• Journal of Energy Engineering
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• v.25 no.3
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• pp.66-72
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• 2016

In this study, a sulfonated poly(arylene ether ketone) block copolymer was prepared from hydrophilic oligomer and hydrophobic oligomer. The structure of the prepared membrane was characterized by $^1H$-NMR, FT-IR and GPC. The $M_w$(weight-average molecular weights) of the polymer was $209,700g\;mol^{-1}$ and the molecular weight distribution($M_w/M_n$) of 1.25 was obtained. The prepared membrane showed excellent thermal stability with gradual weight loss up to $200^{\circ}C$. The proton conductivity of SPAEK block copolymer reached the maximum of $9.0mS\;cm^{-1}$ at $90^{\circ}C$ under 100% relative humidity (RH). From the observed results, it is necessary to do more aggressive attempt to study the possibility of application as an ion-conductive composite electrolyte.

• Applied Chemistry for Engineering
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• v.31 no.5
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• pp.453-466
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• 2020

As the demand for eco-friendly energy increases to overcome the energy shortage and environmental pollution crisis, hydrogen economy has been proposed as a potential solution. Accordingly, an economical and efficient hydrogen production is considered to be an essential industrial process. Research on applying hydrogen separation membranes for H₂/CO₂ separation to the production of highly concentrated hydrogen by purifying H₂ and capturing CO₂ simultaneously from synthetic gas produced by gasification is in progress nowadays. In high temperature environments, the membrane separation process using glassy polymeric membrane with H₂ selectivity has the potential for CO₂ capture performance, and is an energy and cost effective system since polybenzimicazole (PBI)-based separators show excellent chemical and mechanical stability under high-temperature operation conditions. Thus, the development of high-performance PBI hydrogen separators has been rapidly progressing in recent years. This overview focuses on the recent developments of PBI-based membranes including structure modified, cross-linked, blended and carbonized membranes for applications to the industrial hydrogen separation process.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.1
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• pp.28-38
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• 2014

The organic-inorganic composite membrane in polymer exchange membrane fuel cells (PEMFCs) have several fascinating technological advantages such as a proton conductivity, thermal stability and mechanical properties. As the inorganic filler, silicon carbide (SiC) fiber have been used in various fields due to its unique properties such as thermal stability, conductivity, and tensile strength. In this study, composite membrane was successfully fabricated by modified-silicon carbide fiber. Modified process, as a novel process in SiC, takes reaction by phosphoric acid after oxidation process (generated homogeniusly $SiO_2$ layer on SiC fiber). The mechanical property which was conducted by tensile test of the 5wt% modified-$SiO_2@SiCf$ composite membrane was better than that of Aquivion casting membrane as well as ion cxchange capacity(IEC) and proton conductivity. In addition, the single cell performance was observed that the 5wt% modified-$SiO_2@SiCf$ composite membrane was approximately $0.2A/cm^2$ higher than that of a Aquivion casting electrolyte membrane and electrochemical impedance was improved with the charge transfer resistance and membrane resistance.

• Polymer(Korea)
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• v.39 no.1
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• pp.78-87
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• 2015

With aiming to prepare microcapsules having a particle size of $30-50{\mu}m$, thermally expandable capsules with relatively uniform particle sizes consisting of a n-octane/poly(acrylonitrile-co-methyl methacrylate) core/shell structure were synthesized using SPG membrane emulsification and suspension polymerization. Four steric stabilizers and five crosslinking agents were employed. When poly(vinyl alcohol) as a stabilizer was used, the prepared capsules showed a smooth and regular morphology and the liquid hydrocarbon (n-octane) was well encapsulated in the core. When 1,4-butnaediol methacrylate (BDDMA) was used as a crosslinker, the uniform capsules with the average diameter of $36.8{\mu}m$ were synthesized. The capsules prepared with 0.05 mol% BDDMA showed the best encapsulation efficiency.

• Polymer(Korea)
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• v.37 no.3
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• pp.379-386
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• 2013

SAPO-11 was applied for the first time to the catalytic pyrolysis of miscanthus and random polypropylene (random PP). Thermogravimetric analysis confirmed that SAPO-11 promoted the dehydration of miscanthus while suppressing the formation of char. In the pyrolysis of random PP, the decomposition temperature and activation energy were reduced by using a catalyst. A large fraction of levoglucosan, which was the main oxygenate product from the non-catalytic pyrolysis of miscanthus, was converted to high value-added products, such as furans, phenolics and aromatics using SAPO-34. The catalytic pyrolysis of random PP produced gasoline- and diesel-range hydrocarbons.

• Polymer(Korea)
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• v.25 no.4
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• pp.503-511
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• 2001

Present silica dispersing agents are based mainly on fatty acid derivatives of Zn, K and mixture of fatty acid and metallic soaps are used to increase activity. The viscosity of silica filled rubber is lowered by Zn-K soap type silica dispersing agent, thus fluidity of hydrocarbon chains and processibility is improved. Silica dispersing agent should not exert an influence on chracteristics of vulcanization. But scorch and curing time is shortened by Zn-K soap type silica dispersing agent. A newly developed silica dispersing agent, which is a nonmetal type agent, reduced the viscosity and hardness of silica compounding rubber, and the highly increased degree of dispersion of silica is caused by interaction of silica and rubber. Also it did not affect the curing characteristics and scorch stability of silica compounding rubber.