• Proceedings of the Membrane Society of Korea Conference
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• 1996.10a
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• pp.53-54
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• 1996

비대칭 분리막의 제조에 있어서는 용매와 비용매의 교환에 의한 상분리 현상을 이용하기 때문에 용매와 비용매의 성질이 막 제조 공정에 중요한 변수가 된다. 고분자 용액에 공용매를 첨가할 경우 용액의 점도, 용매와 비용매의 상호 작용 정도 등의 용액의 성질을 변화시킬 수 있다. 따라서 이들의 변화에 따른 분리막의 구조 변화를 관찰하여 그 상관 관계를 규명하면 분리막의 미세 구조 조절 및 제어가 가능할 것이다. 본 실험에서는 폴리이미드(PI)를 고분자로 사용하였고, 용매로는 NMP, 공용매로는 $\gamma$-butyrolactone($\gamma$-BL)을 사용하여 고분자의 농도가 15 wt%인 용액을 제조하였다. 제조한 용액을 유리판에 균일한 두께로 casting 한 후 물을 비용매로 사용하여 immersion precipitation 방법으로 막을 제조하였다. 제조한 막은 24시간 동안 물 속에 방치하여 용매를 충분히 제거한 후 상온에서 24시간 이상 건조시켰다. 투과도 측정은 soap bubble flow 방법으로 시행하였으며 단면 구조는 주사전자 현미경을 사용하여 관찰하였다.

• Membrane Journal
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• v.34 no.3
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• pp.192-203
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• 2024

The advancement of commercially viable gas separation membranes plays a pivotal role in improving CO₂ separation efficiency. High-molecular-weight poly(ethylene oxide) (high-Mw PEO) emerges as a promising option due to its high CO₂ solubility, affordability, and robust mechanical attributes. However, the crystalline nature of high-Mw PEO hinders its application in gas separation membranes. This study proposes a straightforward blending approach by incorporating various polymeric additives into high-Mw PEO to address this challenge. Four commercially available, water-soluble polymers, i.e. poly(ethylene glycol) (PEG), poly(propylene glycol) (PPG), poly(acrylic acid) (PAA), and poly(vinyl pyrrolidone) (PVP) are examined as additives to enhance membrane performance by improving miscibility and reducing PEO crystallinity. Contrary to expectations, PEG and PPG fail to inhibit the crystalline structure of PEO and result in membrane flaws. Conversely, PAA and PVP demonstrate greater success in altering the crystal structure of PEO, yielding defect-free membranes. A thorough investigation delves into the correlation between changes in the crystalline structure of high-Mw PEO blend membranes and their gas separation performance. Drawing from our findings and previously documented outcomes, we offer insights into designing and selecting additive polymers for high-Mw PEO, aiming at the creation of cost-effective, commercially viable CO₂ separation membranes.

• Membrane Journal
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• v.27 no.3
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• pp.216-225
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• 2017

Since the experimental proof of one-atom-thick graphene single layer from graphite in 2004, graphene, as a leading material opening two-dimensional world, has been tremendously investigated owing to its intrinsic extraordinary physical properties. Among many promising graphene applications, it is believed that membranes might be one of the first significant applications for graphene and its derivatives (e.g., graphene oxide). Recently, a number of simulation results and proof-of-concept experimental approaches towards graphene membranes reflect such positive prospects. Moreover, graphene and graphene oxide already show many outstanding intrinsic properties suitable for promising membrane platforms, such as the minimum membrane thickness, excellent mechanical strength, high chemical and thermal stability, and the ability to generate nanopores in the two-dimensional, rigid hexagonal lattices or to create slit-like nanochannels between adjacent sheets. In this paper, important theoretical and experimental developments in graphene or graphene oxide-based membranes for gas separation based on intrinsic properties of graphene and its derivatives will be discussed, emphasizing on transport behavior, membrane formation methods, and challenging issues for actual membrane applications.

• Membrane Journal
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• v.25 no.4
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• pp.343-351
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• 2015

In this study, we synthesis polyimide with high gas selectivity using 2,2-bis(3,4-carboxylphenyl) hexafluoropropane, 2,4,6-Trimethyl-1,3-phenylenediamine (DAM) and 4,4-Methylenedianiline (p-MDA), and then the asymmetric membrane was fabricated by non-solvent phase separation method. To confirm the property change of the membrane using different solvent, we measured and compared the viscosity of the polymer solution, cloud point and non-solvent phase separation coefficient. The morphology and gas separation property of membrane prepared by phase separation method was confirmed using Field Emission Scanning Electron Microsope and the single gas permeation measurement apparatus. The single gas ($CH_4$, $N_2$, $O_2$, $CO_2$) permeation property and selectivity value of the membrane prepared with NMP was higher than the membrane prepared with DMAc. We confirmed that the gas selectivity of the membrane increased and the permeation property decreased with increasing of the solvent evaporation time.

• Membrane Journal
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• v.25 no.6
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• pp.547-557
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• 2015

In this study, we synthesized polyimide with high carbon dioxide gas transport property using 2,2-bis(3,4-carboxylphenyl) hexafluoropropane, 2,3,5,6-tetramethyl-1,4-phenylenediamine and poly(ethylene glycol) bis(3-aminopropyl) terminated and then we calculated solubility parameter of synthesized polymer and non-solvent phase separation coefficient to determine proper solvent for preparation of asymmetric membrane, also we measured the viscosity of the polymer solution to check polymer contents in membrane solution and prepare asymmetric membrane with $LiNO_3$ additives. The morphology and gas separation property of membrane prepared by phase separation method was confirmed using Field Emission Scanning Electron Microsope and the single gas permeation measurement apparatus. We confirmed that the carbon dioxide permeance of the membrane increased and the selectivity showed little change with decreasing of the volatile solvent contents.

• Proceedings of the Membrane Society of Korea Conference
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• 1992.04a
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• pp.5-6
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• 1992

폐수처리장치등의 발효조와 매립지등에서 발생하는 biogas는 CO$_2$와 CH$_4$를 주성분으로 하여 $H_2S$, 할로겐화합물, 방향족화합물 등을 포함하고 있으므로 이들 성분들로 인한 환경오염의 방지와 함께, $CH_4$를 가스터빈에 의하여 전력을 생산하거나 천연가스에 상당하는 경제성있는 에너지원으로 변환시키기 위하여 분리, 정제 공정이 필요하다. 본 연구에서는 biogas의 주성분을 이루는 CO$_2$와 CH$_4$를 상용 Cellulose Acetate 막을 이용하여 분리함에 있어서 분리효과에 대한 두 기체와 막 사이의 상호영향을 알아보고자 하였다.

• Membrane Journal
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• v.26 no.3
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• pp.220-228
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• 2016

Carbon molecular sieve (CMS) hollow fiber membranes were prepared by carbonizing a polyimide precursor manufactured by non-solvent induced phase separation process. Gas separation performance of CMS hollow fiber membrane was investigated on the effect of three carbonization conditions. CMS membrane with the highest gas separation performance was obtained at the pyrolysis temperature of $250-450^{\circ}C$: $N_2$, $SF_6$, and $CF_4$ permeance were 20, 0.32, 0.48 GPU, respectively, and $N_2/SF_6$ and $N_2/CF_4$ selectivities were 62 and 42, respectively. In the $SF_6/CF_4/N_2$ mixture gas test, when the stage cut was 0.2, the recovery ratio of $SF_6$ and $CF_4$ was over 99% and 98%. $SF_6$ concentration ratio was 4.5 times higher than the $SF_6$ concentration at the feed side. From the results, it was concluded that CMS membrane was one of the promising membranes for recovery Perfluorocompound gases process.

• Membrane Journal
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• v.22 no.1
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• pp.54-61
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• 2012

To separate and recover of VOCs, supporting membranes using PEI were prepared by phase separation method and it was coated with PDMS to prepare PEI-PDMS hollow composite membrane. To investigate characteristic of prepared membrane, pure gas permeability was measured using oxygen and nitrogen, the stage cut and permeance property with feed concentration were evaluated using xylene, ethyl benzene, toluene and cyclohexane. Also, to check solvent resistance on VOCs, stress-strain property of membrane with immersion time in solvent were measured by DMA. The permeance value of $O_2$ and $N_2$ showed 63 GPU and 30 GPU respectively. Permeated VOCs concentration was decreased with increasing stage cut. But, conversely, recovery efficiency that was increased with increasing stage cut. As a result of DMA test, the stress and strain were 11.93 MPa and 13.52%, respectively.

• Membrane Journal
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• v.31 no.3
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• pp.212-218
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• 2021

It is inevitable to generate incomplete combustion gases when mankind utilizes fossil fuels. From this point of view, gas separation process of combustion gas suggests the possibility of recycling CO gas. In this study, we fabricated a facilitated transport polymeric composite membrane for CO separation using AgBF₄ and HBF₄. The copolymer was synthesized via free-radical polymerization of poly(vinyl alcohol) (PVA) as a main chain and acrylic acid (AA) monomer as a side chain. The polymer synthesis was confirmed by FT-IR and the interactions of graft copolymer with AgBF₄, and HBF₄ were characterized by TEM. PVA-g-PAA graft copolymer membranes showed good channels for facilitated CO transport. In this perspective, we suggest the novel approach in CO separation membrane area via combination of grafting and facilitated transport.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.10a
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• pp.75-76
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• 1997

1. 서론 : 전도성 고분자인 폴리아닐린은 여러 흥미로운 성질을 지니고 있어 많은 연구대상으로 주목받고 있다. 폴리아닐린 필름은 캐스팅이 용이하여 많은 응용을 가져올 것으로 기대된다. 예를 들어 전도성을 부여하는 플라스틱 소자, 전자파 차폐재료 뿐만 아니라 분리용 전도성 고분자막, 의료용 히들로겔 제조 등 이제까지 재료의 제한을 받았던 분야에 응용이 기대되고있다.(생략)