• 한국세라믹학회지
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• 제37권4호
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• pp.376-380
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• 2000

Carbon nanofibers with an average diameter of 100nm were reacted with SiO vapor generated from a mixture of Si and SiO2 to produce silicon carbide nanofibers at temperature ranging 1200∼1500$^{\circ}C$ under vacuum. The nanofiber reacted at 1200$^{\circ}C$ for two hours consisted of silicon carbide with an average crystallite size of 10-20nm, amorphous silica and a significant amount of unreacted carbon. The surface area of silicon carbide nanofiber, obtained after removal of amorphous silica and unreacted carbon from converted carbon nanofibers at 1200$^{\circ}C$, was as high as 150㎡/g. With increasing reaction temperature to 1500$^{\circ}C$, the surface area was decreased to 14㎡/g. Growth of SiC crystallite size with increasing conversion temperature of carbon nanofiber was confirmed from Scherrer formula using the (111) diffraction line and TEM images of converted carbon nanofibers.

• Transactions on Electrical and Electronic Materials
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• 제13권3호
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• pp.121-124
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• 2012

Olivine type $LiFePO_4$ cathode material was synthesized by solid-state reaction method including one-step heat treatment. To improve the electrochemical characteristics, graphite nanofiber (GNF) was added into $LiFePO_4$ cathode material. The structure and morphological performance of $LiFePO_4$ were investigated by X-ray diffraction (XRD); and a field emission-scanning electron microscope (FE-SEM). The synthesized $LiFePO_4$ has an olivine structure with no impurity, and the average particle size of $LiFePO_4$ is about 200~300 nm. With graphite nanofiber added, the discharge capacity increased from 113.43 mAh/g to 155.63 mAh/g at a current density of 0.1 $mA/cm^2$. The resistance was also significantly decreased by the added graphite nanofiber.

• 센서학회지
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• 제23권6호
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• pp.383-387
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• 2014

Electrically conductive polypyrrole-polyvinylpyrrolidone (PPy-PVP) nanofiber mats with a core-shell structure have been successfully fabricated by a two-step process: the formation of FeCl3-containing PVP nanofiber mat by electrospinning, and the vapor-phase polymerization (VPP) of pyrrole monomer on the mat in a sealed chamber at room temperature. Surface morphology and chemical composition of the PPy-PVP mat were characterized by SEM, EDX and FTIR analyses. The as-prepared nonwoven mat was composed of PPy-PVP nanofibers with an average diameter of 300 nm. The sheet conductivity of the nanofiber mat was measured to be approximately 0.01 S/cm by a four-point probe. We have also investigated gas-sensing properties of PPy-PVP nanofiber mat upon exposure to methanol vapor. The PPy-PVP nanofiber sensors were observed to have excellent methanol-sensing performance. The nanofiber-based core-shell nanostructure could give an opportunity to fabricate a highly sensitive and fast response sensor due to its high surfaceto-volume ratio.

• 한국기계가공학회지
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• 제20권11호
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• pp.24-29
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• 2021

In this study, the electrical and mechanical properties of carbon polymer composites, which have been gradually increasing in use in various fields, were investigated, and environment-friendly carbon nanofiber/waterborne polyurethane composites were prepared. Carbon nanofibers (diameter = approximately 100-300 mm) were synthesized using a relatively simple CVD process, obtaining a carbon material for application in ultrathin planar heating films and EMP shielding films in the future. The carbon nanofiber was dispersed, and mixed with water-dispersible polyurethane using a dispersing aid. According to the carbon nanofiber mass ratio, 20%-60% polyurethane/carbon nanofiber composites were manufactured. At a concentration of approximately 20%, the percolation threshold was determined, and at a concentration of approximately 50%, an electrical conductivity greater than 0.1 S/cm was determined. Moreover, a sample having a concentration of up to 60% was evaluated to further understand the mechanical properties. It was observed that as the concentration of the carbon nanofibers increased, the elongation decreased.

• Journal of the Korean Wood Science and Technology
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• 제43권6호
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• pp.730-739
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• 2015

본 연구는 셀룰로오스 나노섬유를 닥나무 인피섬유 시트의 제조시 첨가하여, 닥나무 인피섬유 시트의 특성에 미치는 영향을 조사하였다. 형태학적 및 화학적 성질이 다른 5종류의 셀룰로오스 나노섬유, 즉 리그노셀룰로오스 나노섬유 (lignocellulose nanofiber, LCNF), 홀로셀룰로오스 나노섬유(holocellulose nanofiber, HCNF), 알칼리처리 홀로셀룰로오스 나노섬유(alkali-treated HCNF, AT-HCNF), TEMPO-산화 나노섬유(TEMPO-oxidated nanofiber, TEMPO-NF), 셀룰로오스 나노크리스탈(cellulose nanocrystal, CNC)을 제조하였으며, 각 나노섬유의 종류 및 첨가량이 닥나무 인피섬유시트 제조시의 여수시간 및 시트의 투기도, 평활도, 인장강도 특성에 미치는 영향을 조사하였다. 여수시간은 모든 나노섬유에 있어서 첨가량이 증가함으로서 길어졌으며, 5%의 첨가량에서 HCNF가 가장 여수시간이 길었다. 또한, 셀룰로오스 나노섬유 첨가량이 증가할수록 시트의 평활도, 인장강도 특성이 향상되었으며, 특히 0.1%의 극히 적은양의 나노섬유 첨가로도 비인장강도 및 탄성계수가 크게 향상되는 것을 알 수 있었다. 이러한 특성 향상은 닥나무 인피섬유 간에 교차적으로 적층되어 있는 셀룰로오스 나노섬유의 충전 효과에 기인하는 것을 전자현미경 사진을 통해 확인할 수 있었다.

• 한국분말재료학회지
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• 제15권2호
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• pp.114-118
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• 2008

Functional nanomaterial is expected to have improved capacities on various fields. Especially, metal nanoparticles dispersed in polymer matrix and metal nanofiber, one of the functional nanomaterials, are able to achieve improvement of property in the electric and other related fields. In this study, the fabrication of metal (Ag) nanoparticle dispersed nanofibers were attempted. The Ag nanoparticle dispersed polymer nanofiber and Ag nanofiber were fabricated by electrospinning method using electric force. First, PVP/$AgNO_3$ nanofibers were synthesized by electrospinning in $18{\sim}22kV$ voltage with the starting materials (Ag-nitrate) added polymer (PVP; poly (vinylpyrrolidone)). Then Ag nanoparticle dispersed polymer nanofibers were fabricated to reduce hydrogen reduction at $150^{\circ}C$ for 3hr. And Ag nanofibers were synthesized by the decomposited of PVP at $300{\sim}500^{\circ}C$ for 3hr. The nanofibers were analyzed by XRD, TGA, FE-SEM and TEM. The experimental results showed that the Ag nanofibers could be applied in many fields as an advanced material.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2002년도 춘계총회 및 학술발표회
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• pp.54-55
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• 2002

• Journal of Periodontal and Implant Science
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• 제34권3호
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• pp.543-549
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• 2004

Chitosan has been widely researched as bone substitution materials and membranes in orthopedic/periodontal applications. Chitosan nanofiber membrane was fabricated by chitosan nanofiber using electrospinning technique. The structure of the membrane is nonwoven, three-dimensional, porous, and nanoscale fiber-based matrix. The aim of this study was to evaluate the biocompatibility of chitosan nanofiber membrane and to evaluate its capacity of bone regeneration in rabbit calvarial defect. Ten mm diameter round cranial defects were made and covered by 2 kinds of membranes (Gore-Tex membrane, chitosan nanofiber membrane) in rabbits. Animals were sacrificed at 4 weeks after surgery. Decalcified specimens were prepared and observed by microscope. Chitosan nanofiber membrane maintained its shape and space at 4 weeks. No inflammatory cells were seen on the surface of the membrane. In calvarial defects, new bone bridges were formed at all defect areas and fused to original old bone. No distortion and resorption was observed in the grafted chitosan nanofiber membrane. However bone bridge formation and new bone formation at the center of the defect could not be seen in Gore-Tex membranes. It is concluded that the novel membrane made of chitosan nanofiber by electrospinning technique may be used as a possible tool for guided bone regeneration.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.363.1-363.1
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• 2016

Transparent and stretchable conductors are expected to be an essential component in future stretchable optoelectronic devices. Until now, two main methods have been commonly employed to fabricate transparent and stretchable conductors by using metal nanomaterials: creating buckling configurations and creating network configurations. In this report, a novel strategy for obtaining transparent and stretchable conductors is presented, one that employs these two main approaches simultaneously. To the best of our knowledge, this proposed configuration of a buckled long nanofiber network in this study has not yet been reported. In order to provide the transparent conductors with dual mode stretchability originating from simultaneous buckled and network configurations, a buckled Au@polyvinylpyrrolidone (PVP) nanofiber network (hereafter referred to BANN for convenience) was fabricated by transferring Au-metallized electrospun PVP nanofibers onto a prestrained polydimethylsiloxane (PDMS) substrate. Our BANN shows considerably lower strain sensitivity of resistance than that of straight Au@PVP nanofiber network. Durability tests conducted by performing cyclic tensile strain reveal that the relative change in resistance of BANN (prestrain = 20%) is quite small after 1000 cycles. We also demonstrate that this BANN exhibits superior performance over widely used indium tin oxide conductors with regard to high optical transmittance and low sheet resistance.

• Korean Chemical Engineering Research
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• 제49권1호
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• pp.69-74
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• 2011

본 연구에서는 전기방사를 이용하여 PS의 취성을 개선하고자 내충격성이 우수한 HIPS와 가교제 DVB를 혼합하여 방사한 후 가교와 술폰화 반응을 통해 HIPS 이온교환 나노섬유를 제조하였다. 또한, 이들을 FT-IR, XPS, 함수율, 이온교환 용량, SEM 및 접촉각으로 나노섬유의 기본특성을 확인하였다. FT-IR 및 XPS 구조분석 결과, HIPS 나노섬유는 술폰화 시간이 지남에 따라 $-SO_3H$기의 도입이 증가하는 것을 확인할 수 있었다. 또한 술폰화 시간이 지남에 따라 섬유의 친수성이 증가하여 DVB 함량이 7.5 wt%, 술폰화 시간이 200분일 때 함수율과 이온교환용량은 최대 75.6%, 2.67 meq/g으로 나타났다.