Polytetrafluoroethylene 코팅 처리된 백필터 여재의 여과성능과 물리적 특성

여상영,김숙래,정성훈,Yeo, Sang-Young,Kim, Sook-Rae,Jeong, Sung-Hoon 한국섬유공학회 2005 한국섬유공학회지 Vol.42 No.5

Bag filter media were prepared by a combination of needle punching and thermal bonding processes and treated with Polytetrafluoroethylene(PTFE) aqueous solution. The air permeability of the prepared filter media increased with increasing needle strokes. As needling strokes increased, the pore size distribution became narrow and the tensile strength in the machine and cross direction approached an intermediate value suggesting isotropic nature. From the result of air filter performance test, the pressure difference of bag filter media decreased and the collection efficiency increased with increasing-needle strokes under a constant air flow rate. Both air permeability and average pore size of the coated filter media were largely reduced by the PTFE coating treatment. After PTFE coating, we identified a big decrease in the dust concentration compared with control media. Therefore, the filtration performances such as collection efficiency and pressure difference of bag filter media were promoted by the PTFE coating treatment.

소의 심장 cytochrome c oxidase의 전자전달 특성

李相稷,呂基淑,李在亮,郭天錫,尙瑛錫 嶺南大學校附設 基礎科學硏究所 1988 基礎科學硏究 Vol.8 No.-

Cytochrome c oxidase (complex Ⅳ) was isolated from bovine heart mitochondrion. The spectra of isolated cytochrome c oxidase which was considered to be oxidized showed absorption bands at 598nm and 421nm in the oxidized form and at 604nm and 443nm in the reduced form. The activity of cytochrome c oxidase measured by the redox system of ferrocytochrome c-oxygen was not affected by NH₄OH and ethylenediamine. It was, however, found that 2-mercaptoethanol and potassium cyanide inhibited its reactivity respectively.

용융기반의 PTFE filament 제조 및 특성 연구

김도군,남인우,여상영,양병진 한국고분자학회 2019 한국고분자학회 학술대회 연구논문 초록집 Vol.44 No.2

액체금속이 첨가된 온도 감응성 poly(N-isopropylacrylamide) 하이드로젤의 전기적 특성 변화 고찰

임태환,이소희,여상영 한국염색가공학회 2022 韓國染色加工學會誌 Vol.34 No.3

Hydrogels have gained considerable attention in various fields due to their easily transformative ability by different stimulation. In addition, metal-based conductive additives can enable the hydrogels to be conductive with dimension change. Although the development of the additives offered enhanced electrical properties to the hydrogels, correspondingly enhanced mechanical properties may limit the volume and electrical properties switching after stimulation. Here we prepared poly(N-isopropylacrylamide) (PNIPAM) thermo-responsive hydrogel that has a 32℃ of low critical solution temperature and added liquid metal particles (LMPs) as conductive additives, possessing soft and stretchable benefits. The LMPs enabled PNIPAM (PNIPAM/LMPs) hydrogels to be constricted over 32℃ with a high volume switching ratio of 15.2 when deswelled. Once the LMPs are spontaneously oxidized in hydrogel culture, the LMPs can release gallium ions into the hydrogel nature. The released gallium ions and oxidized LMPs enhanced the modulus of the PNIPAM/LMPs hydrogel, triggering high mechanical stability during repeated swelling/deswelling behavior. Lastly, highly constricted PNIPAM/LMPs hydrogel provided a 5x106 of electrical switching after deswelling, and the switching ratio was closely maintained after repeated swelling/deswelling transformation. This study opens up opportunities for hydrogel use requiring thermo-responsive and high electrical switching fields.

Electrical properties of carbon paper from carbon fiber as function of fluorination

정민정,조한주,여상영,이영석 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0

Carbon papers are frequently used as additional backing in order to improve the gas distribution and water management in the fuel cell. In this work, the carbon paper was prepared from fluorinated chopped carbon fibers to increase electrical conductivity. The chopped carbon fiber surfaces are treated by fluorination method. The fluorination is conducted at 100 °C using fluorine and nitrogen gas at a volume ratio of 2:8. The carbon papers are prepared by wet-laid process with PVA solution. The fluorinated carbon fibers are well dispersed in PVA solution than that non-treated carbon fibers, and the carbon paper prepared with fluorinated carbon fibers have showed the most excellent electrical conductivity.

액체금속을 활용한 플렉서블 섬유상 전극 제조 및 도파민 센서로의 응용

임태환,이소희,여상영 한국섬유공학회 2022 한국섬유공학회지 Vol.59 No.4

Gallium-based liquid metals have gained significant attention as promisingmaterial platforms for flexible bioelectronics owing to their fluidic behavior but still metallic. However, low electrochemical stability owing to oxidation may limit the use of bioelectronicsthat typically operate under physiological conditions. Here, we developed a liquidmetal core/polymer shell fiber platform for flexibility. Then, nanostructured conductivepoly(3,4-ethylenedioxythiophene) (PEDOT) was encapsulated on the liquid metal surfaceto prevent oxidation. Mechanical property measurement demonstrated that the platformdisplayed high flexibility and low Young’s modulus that could minimize the mechanicalmismatch between the fiber platform and soft human tissues. PEDOT encapsulation on theliquid metal surface offered the fiber platform-based electrode considerably higher electrochemicalproperties, such as lower impedance and higher charge storage capacity. Theimproved electrochemical performance enables the liquid metal-based fiber electrode tobe used for electrochemical dopamine (DA) monitoring. This study demonstrated that thePEDOT structured flexible electrode had a sensitivity of 0.218±0.022 μA/μM and a limit ofdetection of 150 nM. Finally, the electrode could effectively detect DA under a plethora ofbyproducts produced by human metabolism. All the results confirmed the flexibility andremarkable electrochemical properties of the prepared liquid metal-based electrode,opening numerous design opportunities for next-generation liquid metal-based bioelectronics.

Behavior of Polybenzoxazine Composites Reinforced with Modified Carbon Nanotubes

안다미로,최현정,여상영,김호동 한국섬유공학회 2021 Fibers and polymers Vol.22 No.2

The surface of conventional carbon nanotube (CNTs) were modified into 4-aminobenzoyl functionalized CNTs(ABCNT) and benzoxazine functionalized CNTs (BZCNT) to improve their surface interaction with bisphenol A basedbenzoxazine resins (BA-a). Polybenzoxazine (PBZ) composites using these materials were prepared to investigate the effectof different functional groups on the thermal and electrical properties of the composites. The surface modification of CNTswas characterized by Fourier Transform Infrared spectroscopy and thermogravimetric analysis. The PBZ composite withBZCNT showed the better conductivity and thermal properties than the composite with ABCNT due to the chemical bondbetween BZCNT/ BA-a during the curing process which does not exist in the ABCNT/BA-a composite.

PTFE/아라미드 복합 백필터 여재 제조 및 특성

배영환,공다정,이소희,여상영 한국섬유공학회 2020 한국섬유공학회지 Vol.57 No.5

Nonwoven fabrics are widely used as filter bags in dust collection facilities, which are industrial air pollution prevention facilities with high dust collection efficiency. The filter bag media is the most important factor that determines the performance of the pulse-jettype dust collection facility. In general, the materials used for filter bag media are polyester, nylon, and polypropylene fibers. Because of the effects of the operating temperature, meta-aramids and polyphenylene sulfide are used at a high temperature of around 200 °C, while glass fiber, polyimide, and polytetrafluoroethylene (PTFE) are used at an ultra-high temperature of approximately 260 °C. Among these, PTFE membranes show/exhibit excellent heat resistance, chemical resistance, non-adhesiveness, and filtration efficiency. Despite the advantages of these fibers, there are no studies on the preparation and properties of filter bag media mixed with meta-aramid staple and PTFE fibers. Therefore, in this study, expanded PTFE filaments were processed into staple fibers to enable carding; mixed with meta-aramid staple fibers by ratio to form the upper and lower webs; and then applied with a PTFE and aramid scrim. The filter bag media was manufactured through a needle punching process and finishing. The air permeability, pore size, tensile strength, filtration performance, and durability of the prepared mixed filter bag media were evaluated. The results show that the prepared low differential pressure filter bag media had improved heat resistance and durability, while maintaining the 100% dust collection efficiency of the existing aramid medium.

창상피복재용 어피 콜라겐 복합섬유 및 부직포 제조

곽현중,안현철,배영환,이원준,여상영 한국섬유공학회 2022 한국섬유공학회지 Vol.59 No.1

Collagen is used in various medical and cosmetic materials as a biopolymer. Inorder to use it for high-end medical fibers, its mechanical properties must be improved,and this can be achieved by conjugating it with fish-skin-based collagen and chitosan. Theconjugated collagen fibers can utilize the advantages of the materials and can be appliedto make wet-laid nonwovens for wound dressing. In this study, the conjugated collagenfibers were prepared by wet spinning and their surface, optical, and mechanical propertieswere analyzed based on the various compositions of collagen and chitosan. In addition,the wet-laid nonwovens were manufactured with bilayers, designed with an inner layer ofconjugated collagen fibers and an outer layer of cotton/chitosan spunlace nonwoven. Thecharacteristics of the wet-laid nonwovens in terms of their liquid-handling properties andthe distribution of their pore sizes were investigated. The results thus obtained show thatthe use of conjugated fibers in wet-laid nonwovens can affect their properties, which canbe controlled by adjusting the composition ratio.

셀룰로스 나노피브릴을 이용한 재활용 탄소섬유 습식부직포의 기계적 물성 연구

윤철민,배영환,김우식,여상영 한국섬유공학회 2021 한국섬유공학회지 Vol.58 No.1

Carbon fiber is an advanced material widely used in high-tech industries becauseof its light weight, heat resistance, chemical resistance, excellent mechanical properties, andelectrical and thermal conductivity. However, carbon fibers also have high production costsand limited disposal methods (e.g., landfills). Research is being conducted to address theseproblems through the recycling of carbon fibers. Among the representative recycled carbonfiber products, wet nonwoven fabrics have limitations in their mechanical propertiesbecause their structure simply consists of stacked microsized-diameter carbon fibers and abinder. In this study, the tensile strength was improved by adding cellulose nanofibrils(CNFs) during the manufacturing of wet nonwoven fabrics by mixing short-cut carbonfibers and a binder (short-cut PVA fibers). CNF bundles improve the mechanical propertiesby forming a complex structure via the crosslinking of carbon fibers and short PVA fibers. The tensile strength of nonwoven fabrics consisting of short carbon fibers and PVA fiberswas determined to be 92 gf. On the other hand, the tensile strength of the nonwoven fabricwith 10% CNF added to the binder increased by approximately 20 times to 1,808 gf. Thecomposite with nanofiber was confirmed to be effective in forming a structure with highmechanical properties when fabricating microfiber-based nonwoven fabrics.