• 한국막학회:학술대회논문집
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• 한국막학회 1998년도 추계 총회 및 학술발표회
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• pp.112-114
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• 1998

막분리기술은 분릿대상 성분과 분리매체와의 분자 사이의 힘의 차를 이용하여 분리하는 기술이기 때문에 분리특성을 고도로 기능화시키는 것이 가능하다. 또한 막분리 기술 자체가 에너지 절약기술이기 때문에 차세대 분리기수로서 중요한 역할을 할 수 있다. 이와 같은 분리기술은 역삼투법 등의 수용액계와 상온 부근의 기체분리막은 실용화되어 있다. 그러나 비수용액계 또는 고온 공정에서 특수한 조건하에서 고기능성 분리성능을 가지는 막의 개발에 대한 요구가 증대되고 있다. 이에 대응하여 내열성, 내용제성이 우수한 고분자에 의한 분리성능을 요구한다. 특히 근년에는 방향족 polyimide 수지가 주목을 받고 있으며, 내열성, 내구성 및 기계-전기적 특성이 우수한 재질로 광범위하게 사용되고 있다. 이것은 분자 구성기가 가지는 결합에너지가 크고, 분자의 규칙성에 의한 유리전이온도가 높아서 250-300$\circ$C의 고온에서도 사용이 가능한 재료로서 한외여과막과 기체분리막으로 시판되고 있다.

• 한국막학회:학술대회논문집
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• 한국막학회 1997년도 추계 총회 및 학술발표회
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• pp.39-45
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• 1997

Introduction : Polyimides are one of the most important classes of the high performance polymers due to their excellent electrical, thermal, and high-temperature mechanical properties. But their uses are limited because of their poor solubility. Most polyimide derivatives are processed in the form of polyamic acids, which are subsequently converted into the imide structures.Recently, it has been found that the soluble polyimides with large molecular weight sufficient to application. For enhancing processability, the majority of approaches have involved the following factors. As much as, the separation of the imide ring along the back-bone, that is to say, reducing the density of imide ring in the repeat structure. The introduction of bulky substituents along the back-bone, in order to enhance the free volume of main-chain. The incorporation of flexible or thermally stable linkages in the main-chain, reducing the packing force. The disruption of symmetry or recurrence regularity through copolymerization in order to reduce crystallnity.The objectives of this investigation are the synthesis and characterization of soluble polyimides as membrane materials by the single-step polymerization and the preparation of the asymmetric polyimide membrane by using phase inversion technique. In the present study, three series of polyimide derivatives are synthesized; H series is homopolyimides, A series is prepared from single dianhydride and two diamines, B series is yielded from two dianhydrides and a diamine. The dope solution was directly prepared from the PI solution via one step polymerization from monomers.

• 한국막학회:학술대회논문집
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• 한국막학회 1999년도 The 7th Summer Workshop of the Membrane Society of Korea
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• pp.27-30
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• 1999

Poly(phenylene oxide)s were used to prepare flat, integrally skinned self-supporthed asymmetric membranes by dry-wet phase separption. The intrinsic ideal gas selectivity of poly- (2,6-dimethy-1,4-phenylene oxide) (PMPO) was retained in the membranes, and improved by a coating with silicone rubber. Polymers of the same class were coated of UF supports with a silicon rubber gutter layer, yielding composite membranes with high flux but lower selectivity. The effect of th glutaraldehyde cross-linking of sodium alginate (SA) membranes on the mobility of water and ethanol has been studied with pfg nmr. Crosslinking reduces water self-diffusion, and does not seem to be stable on the timescale of weeks.

• Environmental Engineering Research
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• 제23권3호
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• pp.316-322
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• 2018

In this study, the effects of polymer concentration and additive in the formation of asymmetric nanofiltration (NF) membrane were evaluated. The membrane fabrication was carried out via dry/wet phase inversion technique. A new formulation of dope solution with polymer concentration ranging between 17 wt% to 21 wt% and the present of additive was developed. The results show that the permeate flux gradually decreases as polymer concentration increased, until $2.5969L/m^2h$ and increased the rejection up to 98.7%. Addition of additive, polyethylene glycol 600 increased dyes rejection up to 99.8% and decreased the permeate flux to $3.6501L/m^2h$. This indicates that the addition of polyethylene glycol additive led towards better membrane performance. The morphological characteristics of NF membrane were analysed using a Scanning Electron Microscopy.

• 한국막학회:학술대회논문집
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• 한국막학회 1998년도 추계 총회 및 학술발표회
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• pp.11-14
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• 1998

1. Introduction : Research progresses in Chemistry and Chemical Engineering have been made during the last decades with important contributions to the industrial development and to the quality of our life. An interesting case is related to the membrane science and technology continuous impact to innovative processes and products, particularly appropriate for a sustainable industrial growth. Membrane operations have been familiar for many years to biologists and chemists working in their laboratorier or studying biological phenomena. Only recently engineers started to operate in' this area. The preparation of asymmetric CA membranes at University of California, Los Angeles in the early 60s is generally recognized as a crucial moment for membranology (1). Loeb and Sourirajan with their discovery of how to increase significantly the permeability of polymeric membranes without significant changes in their selectivity, made realistic the possibility of their use in large scale operations for desalting brackish and sea water by reverse osmosis and for various other molecular separations in different industrial areas. Reverse osmosis is today a well recognized basic unit operations, togheter with ultrafiltration, crossflow microfiltration,. nanofiltration, all pressure driven membrane processes. Already in 1992 more than 4 milIions m$^3$/day were the total capacity of RO desalination plants and in 1995 more than 180.000 m$^2$ of ultrafiltration membranes were installed for the treatment of wheys and milk (2) (3).

• 멤브레인
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• 제15권3호
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• pp.198-205
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• 2005

방사능 오염도 측정에 사용하기 위한 이중구조 고분자막이 폴리설폰과 세륨활성화된 이트륨실리케이트(CAYS)를 이용하여 제조되었다. 제조된 막은 순수 고밀도 고분자 지지층과 이에 제막된 고분자 용액의 상전환 공정에 의해 고형화된 CAYS 함침 활성층의 이중구조로 구성된다. 제막공정에서 대기방치 공정이 생략되었을 때 CAYS를 포함하는 활성층은 전형적인 비대칭 구조를 지니며, CAYS 입자들이 고분자 구조 사이에 박혀있는 형상을 지닌다. 제막공정에서 대기에 방치하는 시간이 증가할수록 막의 형상은 스폰지 구조를 띠며 CAYS는 고분자 구조로부터 분리되어 막 내부에 셀 같은 공간에 밀집되어 존재함을 보였다. 한편, 두 충 사의 계면형상은 고분자 고형화 과정에서의 상전환 속도와 밀접한 관련되었으며, 대기방치 시간의 증가에 따라 계면의 구분이 뚜렷하게 나타나지 않았다. 방사능 탐지 특성에서 스폰지 구조를 지니는 막의 고분자 구조는 방사성핵종이 통과할 수 없는 밀집된 형상을 지니면서 탐지효율의 감소를 초래하는 것으로 나타났다.

• Membrane and Water Treatment
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• 제9권5호
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• pp.317-325
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• 2018

Polyvinyl chloride (PVC) ultrafiltration (UF) membrane was modified by silica sol in the coagulation bath during non-solvent induced phase separation (NIPS) process. The effects of silica sol concentrations on the morphology, surface property, mechanical strength and separation property of PVC UF membranes were systematically investigated. PVC membranes were characterized by Fourier transform infrared spectroscopy (FTIR), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), contact angle goniometry and tensile strength measurement. The results showed that silica had been successfully assembled on the surface of PVC UF membrane. With the increase of silica sol concentration in the coagulation bath, the morphologies of PVC UF membranes changed from cavity structure to finger-like pore structure and asymmetric cross-section structure. The hydrophilicity and permeability of PVC UF membranes were further evaluated. When silica sol concentration was 20 wt.%, the modified PVC membrane exhibited the highest hydrophilicity with a static contact angle of $36.5^{\circ}$ and permeability of $91.8(L{\cdot}m^{-2}{\cdot}h^{-1})$. The structure of self-assemble silica had significant impact on the surface property, morphology, mechanical strength and resultant separation performance of the PVC membranes.

• Membrane and Water Treatment
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• 제7권3호
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• pp.257-275
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• 2016

The enantiomeric and racemic effects of tartaric acid (TA) on the properties of polysulfone (PSn) ultrafiltration membranes were studied in terms of morphology and hydrophilicity (HPCT) of membrane. Asymmetric membranes were prepared by direct blending of polyvinyl pyrrolidone (PVP) with D-TA and DL-TA in membrane casting solution. FTIR analysis was done for the confirmation of the reaction of PVP and TA in blended membranes and plain PSn membranes. Scanning electron microscope (SEM), field emission scanning electron microscope (FESEM) and atomic force microscopy (AFM) were used for analyzing the morphology and structure of the resulting membranes. The membranes were characterized in terms of pure water flux (PWF), hydraulic permeability and HPCT. PWF increased from $52L/m^2h$ to $79.9L/m^2h$ for plain and D-TA containing PSn membrane, respectively. Water contact angle also found to be decreased from $68^{\circ}$ to $55^{\circ}$. In Additionally, permeation and rejection behavior of prepared membranes was studied by bovine serum albumin (BSA) solution. A considerable increase in BSA flux (from $19.1L/m^2h$ for plain membrane to $32.1L/m^2h$ for D-TA containing membrane) was observed. FESEM images affirm that the pore size of the membranes decreases and the membrane permeability increases from 0.16 to 0.32 by the addition of D-TA in the membrane. D-TA increases the HPCT whereas; DL-TA decreases the HPCT of PSn membrane. PVP (average molecular weight of 40000 Da) with D-TA (1 wt%) gave best performance among all the membranes for each parameter.

• 한국세라믹학회지
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• 제50권6호
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• pp.390-395
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• 2013

Nanocrystalline CrN films were deposited on Si (100) substrates by means of asymmetric pulsed DC reactive magnetron sputtering. We investigated the growth behavior, corrosion resistance and mechanical properties of CrN films with a change in the duty cycle and pulse frequency. The grain size of the CrN films decreased from 25.4 nm to 11.2 nm upon a decrease in the duty cycle. The corrosion potentials for the CrN films by DC sputtering was approximately - 0.6 V, and it increased to - 0.3 V in the CrN films which underwent pulsed sputtering. The nanoindentation hardness of the CrN films also increased with a decrease in the duty cycle. This enhancement of the corrosion resistance and mechanical properties of pulsed sputtered CrN films could be attributed to the densification and surface smoothness of the microstructure of the films.

• 멤브레인
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• 제15권1호
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• pp.22-33
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• 2005

비대칭 폴리비닐리덴플루오라이드(PVDF) 막을 상전환법으로 제조하였다. 도포용액은 PVDF를 용매인 N-ethyl-2-pyrrolidone (NMP)와 비용매인 1,4-dioxane, diethyleneglycol dimethyl ether (DGDE), acetone, (equation omitted)-butyrolactone(GBL)의 혼합용매에 녹여서 제조한다. 여러 첨가제가 도포용액 특성, 투과특성과 막 구조에 미치는 영향을 조사하였다. 응고제인 물과 1,4-dioxane, DGDE, acetone과의 상용성이 NMP보다 낮아서 기공크기가 작아진다. 첨가제의 양을 조절하여 기공크기를 변화시켰다. 혼합용매(수계 및 비수계)가 막의 투과성능에 미치는 영향을 살펴보았다. 용액점도뿐만 아니라 표면장력도 용매 투과특성에 영향을 끼침을 알 수 있었다.