• Journal of Electrochemical Science and Technology
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• 제12권1호
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• pp.74-81
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• 2021

Silicon (Si) is recognized as a promising anode material for high-energy-density lithium-ion batteries. However, under a condition of electrode comparable to commercial graphite anodes with low binder content and a high electrode density, the practical use of Si is limited due to the huge volume change associated with Si-Li alloying/de-alloying. Here, we report a novel core-shell composite, having a reversible capacity of ~ 500 mAh g-1, by forming a shell composed of a mixture of nano-Si, graphite nanosheets and a pitch carbon on a spherical natural graphite particle. The electrochemical measurements are performed using electrodes with 2 wt % styrene butadiene rubber (SBR) and 2 wt.% carboxymethyl cellulose (CMC) binder in an electrode density of ~ 1.6 g cm-3. The core-shell composites having the reversible capacity of 478 mAh g-1 shows the outstanding capacity retention of 99% after 100 cycles with the initial coulombic efficiency of 90%. The heterostructure of core-shell composites appears to be very effective in buffering the volume change of Si during cycling.

• Composites Research
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• 제36권2호
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• pp.126-131
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• 2023

기존의 상용 플라스틱으로 인한 환경 오염에 대한 우려가 높아지면서 대체 재료로서 생분해성 고분자에 대한 연구가 주목을 받고 있다. 본 연구는 생분해성 열가소성 수지인 폴리 젖산에 유기 핵제의 도입으로 물성 강화 및 100% 생분해 가능한 나노복합재 개발을 목표로 한다. 그에 따라 무기 핵제의 대체재로 친환경 소재인 셀룰로오스 나노섬유를 채택하였다. 폴리 젖산 내 셀룰로오스 나노섬유의 균일한 분산을 위해 동결 건조 방식으로 나노화된 섬유 형상을 유지시켰으며, 이축압출기로 1차 교반을 진행하고, 사출 성형을 통해 이중 교반된 물성 시험용 시편을 제작하였다. 보강된 결정성을 확인하기 위해 시차주사 열량분석법을 사용하였고 1 wt%의 셀룰로오스 나노섬유가 보강재 및 핵제로서 작용하여 냉결정화온도가 약 14℃ 가량 감소하며, 결정화되는 정도 또한 증가한 것을 확인하였다. 본 연구는 기존 생분해성 고분자의 무기 핵제를 유기 나노소재로 대체함으로써 100% 생분해 가능한 친환경 나노복합재 개발하여 강화된 물성의 플라스틱 소재 개발을 위한 친환경적 대안을 제시한다.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 봄 학술발표회 논문집
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• pp.179-182
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• 2003

Chitin is the most abundant natural amino polysaccharide and is estimated to be produced annually almost as much as cellulose. It has become of great interest not only as an under utilized resource, but also as a new functional material of high potential in various fields. In addition, chitin and chitosan are recommended as suitable functional materials, because these natural polymers have excellent properties such as biocompatibility, biodegradability, non-toxicity and adsorption properties, etc. (omitted)

• Korean Chemical Engineering Research
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• 제56권1호
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• pp.56-60
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• 2018

미세입자가 미치는 부정적인 영향으로 인해 관심이 증가하여 공기 중 미세입자를 제거할 수 있는 멤브레인 필터의 성능향상을 위해 다양한 방법을 도입하여 왔다. 필터 섬유 제조 기술 중 전기 방사 기술이 최근에 가장 주목을 받고 있으며, 수 백 nm에서 수 십 ${\mu}m$ 까지의 균일한 직경의 섬유를 제조 할 수 있는 장점을 가진다. 전기 방사 기술로 생성한 섬유는 초극세 섬유로서 섬유의 생성과 동시에 3차원의 네트워크로 적층된 형태의 다공성 웹은 초박막, 초경량이며 기존 섬유에 비해 부피 대비 표면적비가 높고, 높은 기공도를 가지는 멤브레인을 제조 할 수 있으므로, 전기 방사 멤브레인의 여과 필터 성능이 크게 향상 될 것으로 예상이 된다. 본 연구에서는 polystyrene, cellulose acetate 멤브레인 필터를 이용하여 섬유 두께, 탄소나노튜브의 조성비에 따른 필터로서의 여과성능을 살펴보았으며, 필터소재의 성능 비교실험 결과 적정량의 CNT 소재의 첨가로 인해 필터의 여과 성능이 향상되는 것을 알 수 있다.

• Journal of Veterinary Science
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• 제23권1호
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• pp.1.1-1.11
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• 2022

Background: The poor bioadhesion capacity of tilmicosin resulting in treatment failure for Staphylococcus aureus small colony variants (SASCVs) mastitis. Objectives: This study aimed to increase the bioadhesion capacity of tilmicosin for the SASCVs strain and improve the antibacterial effect of tilmicosin against cow mastitis caused by the SASCVs strain. Methods: Tilmicosin-loaded chitosan oligosaccharide (COS)-sodium carboxymethyl cellulose (CMC) composite nanogels were formulated by an electrostatic interaction between COS (positive charge) and CMC (negative charge) using sodium tripolyphosphate (TPP) (ionic crosslinkers). The formation mechanism, structural characteristics, bioadhesion, and antibacterial activity of tilmicosin composite nanogels were studied systematically. Results: The optimized formulation was comprised of 50 mg/mL (COS), 32 mg/mL (CMC), and 0.25 mg/mL (TPP). The size, encapsulation efficiency, loading capacity, polydispersity index, and zeta potential of the optimized tilmicosin composite nanogels were 357.4 ± 2.6 nm, 65.4 ± 0.4%, 21.9 ± 0.4%, 0.11 ± 0.01, and -37.1 ± 0.4 mV, respectively; the sedimentation rate was one. Scanning electron microscopy showed that tilmicosin might be incorporated in nano-sized crosslinked polymeric networks. Moreover, adhesive studies suggested that tilmicosin composite nanogels could enhance the bioadhesion capacity of tilmicosin for the SASCVs strain. The inhibition zone of native tilmicosin, tilmicosin standard, and tilmicosin composite nanogels were 2.13 ± 0.07, 3.35 ± 0.11, and 1.46 ± 0.04 cm, respectively. The minimum inhibitory concentration of native tilmicosin, tilmicosin standard, and tilmicosin composite nanogels against the SASCVs strain were 2, 1, and 1 ㎍/mL, respectively. The in vitro time-killing curves showed that the tilmicosin composite nanogels increased the antibacterial activity against the SASCVs strain. Conclusions: This study provides a potential strategy for developing tilmicosin composite nanogels to treat cow mastitis caused by the SASCVs strain.

• 멤브레인
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• 제20권4호
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• pp.304-311
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• 2010

본 연구에서는 셀룰로오스 트리아세테이트(CTA)를 사용한 loose RO 중공사 막이 상전환 법으로 제조되었고 이들의 수처리 특성이 평가되었다. 1,4-dioxane과 리튬클로라이드(LiCl)는 각각 스킨층 형성제와 기공 형성제로 사용되었다. 제조된 CTA 중공사막의 특성을 알아보기 위하여 전자주사현미경을 통하여 모폴로지를 관찰하였고, 수투과도 및 염 제거율, 내염소성 테스트, 그리고 분획분자량을 측정하였다. CTA/NMP/1,4-dioxane = 18/72/10 (wt%) 에어갭 30 cm의 중공사 분리막의 경우 $20.5L/m^2hr$의 수투과도와 60%의 염 제거율, NaOCl 10,000 ppm/hr의 내염소성 및 약 5,000 Da값의 MWCO를 나타내는 우수한 특성의 loose RO 막이 제조되었다.

• Korean Chemical Engineering Research
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• 제54권1호
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• pp.114-119
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• 2016

본 연구에서는 박테리아 셀룰로오스(BC)와 같은 천연고분자에 전도성 고분자 PEDOT:PEG와 graphene, 은나노와이어(AgNW)를 코팅하여 전도성을 부여하고자 하였다. 미리 PEDOT:PEG와 황산을 10~20%를 혼합하여 그 용액을 전자 스핀 코팅으로 BC 기판에 코팅하였다. 그 후, 전도성을 향상시키고자 graphene과 AgNW로 코팅하여 hall effect로 측정하였다. 그 결과, 대조군 PEDOT:PEG로 코팅한 BC 막의 전자농도($2.487{\times}10^{10}/cm^3$)에 비해 PEDOT:PEG에 황산을 10%로 혼합하여 코팅시킨 BC막($8.093{\times}10^{15}/cm^3$) 쪽이 $3.25{\times}10^5$배 높은 값을 나타내는 것으로 전도도가 대폭 향상되었음을 알 수 있었다. 또한, SEM분석으로 PEDOT:PEG가 황산처리에 의해 폴리머 형상으로 변화된 것을 확인 할 수 있었다. 분자구조의 변화를 FTIR분석결과 $1200cm^{-1}$ 파장의 S-O그룹이 황산처리 전에 비해 황산 혼합한 쪽에서 크게 상승된 것이 확인되었다. 이 방법을 이용하여 소량의 PEDOT:PEG사용으로 투명성을 확보할 수 있으며 미리 황산을 처리하는 것으로 제조공정을 단순하게 할 것으로 사료된다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2007년도 추계학술발표논문집
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• pp.93-102
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• 2007

Biocomposite was organized with biodegradable polymer and natural fiber that has potential to be used as replacement for glass fiber reinforced polymer composite with the benefits of low cost, low density, acceptable specific strength, biodegradability, etc. Until now, non-wood fibers have been used as reinforcements of biocomposite which are all plant-based fibers. The present study focused on investigating the fabrication and characterization of biocomposite reinforced with red algae fiber. The bleached red algae fiber(BRAF) showed very similar crystallinity to the cellulose. It has high stability against thermal degradation (maximum thermal decomposition temperature of 359.3$^{\circ}C$) and thermal expansion. Biocomposites reinforced with BRAF have been fabricated by a compression molding method and their mechanical and thermal properties have been studied. The storage modulus and the thermomechanical stability of PBS matrix are markedly improved with reinforcing the BRAF. These results support that the red algae fiber can be used as an excellent reinforcement of biocomposites as "green-composite" or "eco-composite".

• 펄프종이기술
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• 제40권1호
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• pp.62-67
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• 2008

Biocomposite was fabricated with biodegradable polymer and natural fiber that has potential to be used as replacement for glass fiber reinforced polymer composite with the benefits of low cost, low density, acceptable specific strength, biodegradability, etc. Until now, mostly natural cellulosic fibers on land have been used as reinforcement for biocomposite. The present study focused on investigating the fabrication and the characterization of biocomposite reinforced with red algae fibers from the sea. The bleached red algae fiber (BRAF) showed very similar crystallinity to the wood cellulose. It has high stability against thermal degradation (maximum thermal decomposition temperature of 359.3$^{\circ}C$) and thermal expansion. Biocomposites reinforced with BRAF have been fabricated by a compression molding method and their mechanical and thermal properties have been studied. The storage modulus and the thermomechanical stability of PBS (polybuthylenesuccinate) matrix are markedly improved by reinforcing with the BRAF. These results indicate that red algae fiber can be used as an excellent reinforcement of biocomposites, which are sometimes called as "green-composites" or "eco-composites".

• Advances in nano research
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• 제15권4호
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• pp.329-337
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• 2023

Wearing the right sportswear is one of the essential points in exercising, which is mainly neglected. Sportswear should be suitable for the ambient temperature and not cause more heat or cold in the athlete's body. On the other hand, increased sweating and blood circulation during exercise should not cause fatigue or heatstroke in the athlete. Nanotechnology has grown significantly in the field of producing more efficient equipment in the field of sports. The increase in demand in sports for complete sports equipment has revealed the necessity of using the highest quality materials in this sector. In the world of championship sports, a minor change in equipment can lead to significant changes in causing failure and victory. Since the sole is the most critical part of sports shoes, with the introduction of nanotechnology and nanocomposites, it is possible to help athletes rush and increase their sense of calm and satisfaction. Using nanocomposites in the soles of shoes can improve some of their characteristics, prevent the smell and sweat of shoes, and induce water repellency in these shoes. In this research, titanium dioxide (TiO₂) nanocomposite, along with cellulose, has been used to create antibacterial and hydrophobic properties in the soles of sports shoes. The synthesized nanocomposite has been synthesized using the least amount of chemicals, which shows this method's easy and cost-effective synthesis.