• Journal of the Korean Society of Clothing and Textiles
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• v.48 no.4
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• pp.673-687
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• 2024

In this study, we first analyzed the total polyphenol and flavonoid contents and the antioxidant activity of Dendropanax morbiferus extracts obtained from different parts using different solvents. We then investigated the possibility of producing Dendropanax morbiferus leaf extract loaded polyurethane (PU) nanofibers via electrospinning. The total polyphenol and flavonoid content and the antioxidant activity of the Dendropanax morbiferus leaf extracts obtained distilled water were found to be higher than those of the extracts obtained under other conditions, and it was therefore used to prepare the extracts/PU nanofibers by varying the concentrations of both the Dendropanax morbiferus leaf extract and PU. The most appropriate fiber morphology were when 1.5% and 1.0% of the Dendropanax morbiferus leaf extracts were added to 12% and 13% PU, respectively. Fourier-tranform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) analyse reveal the successful incorporation of the Dendropanax morbiferus leaf extracts into the PU matrix. In addition, the nanofibers containing this leaf extract were confirmed to exhibit antibacterial properties against Staphylococcus aureus, suggesting the potential usefulness of nanofacial masks containing the Dendropanax morbiferus leaf extract.

• Composites Research
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• v.33 no.2
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• pp.50-54
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• 2020

Soft robotics and wearable devices require large motions and flexibility. In this regard, there is a demand for developing stretchable strain sensors which can be attached to the soft robots and wearable devices. In this work, we fabricated stretchable and electrically conductive composite fibers by combining polyurethane (PU) and silver nanoflowers (AgNFs). The PU/AgNF composite fibers showed the change of the resistance as a function of the applied strain, demonstrating the potential for stretchable strain sensors in soft robotics and wearable devices. The mechanical and electrical characteristics of the composite fibers were measured and analyzed to use the composite fibers for stretchable strain sensors.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.11
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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.

• Proceedings of the Korean Fiber Society Conference
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• 2007.11a
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• pp.543-544
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• 2007

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.3
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• pp.120-126
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• 2018

In the present study, the multi-nozzle electrospinning process is investigated for the fabrication of uniform polymer nanofiber mats. Electrospinning has been one of the simple and efficient methods to manufacture polymer nanofibers and their mats. Although a typical electrospinning has many advantages such as simple system and operation, various materials, and cost-effectiveness, a relatively low productivity prevents it from being used in practical applications. Thus, the multi-nozzle electrospinning system with the adjustable nozzle position and rotating drum collector is designed and produced in this study. In particular, the effects of the inter-nozzle distance and spatial arrangement of nozzles on the uniformity of the electrospun nanofibers are investigated. With this multi-nozzle electrospinning process, the maximum flow rate of the supplied polymer solution for a uniform electrospinning increases, which indicates the enhanced productivity.

• Journal of the Korean Applied Science and Technology
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• v.38 no.6
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• pp.1533-1542
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• 2021

Eco-friendly polyurethane can be defined as a highly utilized material used in various fields. The various structural properties of the synthesis of isocyanates and polyols provide versatility and customization for use in the manufacturing field. The characteristics of polyurethane vary widely from soft touch coatings to hard building materials like rocks. These mechanical, chemical and biological properties and ease of alignment are drawing tremendous attention not only in the field of research but also in related industries. In order to improve the performance of water-dispersible polyurethane materials, it can be derived through processes such as adjusting the blending of raw materials and adding additives and nanomaterials. This study highlights the basic chemical structure of eco-friendly water-dispersible polyurethane in the fields of medical science, automobiles, coatings, adhesives, paints, textiles, marine industries, wood composite materials, and clothing.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.58-58
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• 2011

CNT 나노기술을 응용한 IT산업용 적층간지용 ESD(정전방전, Electrostatic Dissipation)PU 발포필름의 제조 가공기술 및 상품화 개발은 전자제품 패키지에 요구되는 쿠션성과 정전방전 기능을 갖는 폴리우레탄 발포 필름의 제조기술을 확립함으로써 가능 할 수 있다. 특히 IT산업용 필름제품이 개발되면 ESD 성능을 발휘하게 됨으로서 정전기 쇼크에 의한 각종 전자제품의 오작동이나 파손 방지가 가능하게 되어 포장재, 자동차, 전자제품의 하우징 등으로 사용될 수 있게 된다. 현재까지 ESD 기능을 부여하기 위해서 사용되는 충전재로는 금속섬유, 금속플레이크, 탄소섬유, 카본블랙 등이 있으며, 최근 탄소나노튜브를 응용한 연구가 많이 진행되고 있는데 탄소나노튜브는 직경이 수십nm, 종횡비 1000이상의 나노섬유형태로 서 전기전도성이 구리수준으로 알려져 있고 소량을 충전할 시 기계적 특성도 오히려 증대하는 장점을 가지고 있으며 전기적 특성으로는 상대적으로 낮은 나노튜브 함량에서는 ESD를 들 수 있고 높은 함량에서는 전자파 차폐성까지 기대되고 있다. 본 연구에서는 우수한 인장강도, 기계적 강도, 열적 안정성, 내약품성을 가지면서 습식 또는 용융공정을 통해 용이하게 시트, 필름, 코팅제를 제조할 수 있는 방수, 투습방수성을 가지는 유연재료인 폴리우레탄(PU) 1액형 PU에 MWNT 함량이 3wt%인 IPA/MWNT 분산용액을 PU 함량 대비 20, 30, 40파트로 함유시켜 $120^{\circ}C$에서 2분 건조시켜 제조한 그라운드 필름에 2액형 PU와 IPA/MWNT 분산용액에 발포제를 첨가하여 발포온도 140, 150, $160^{\circ}C$에서 5분간 건조시켜 시료 필름을 제조하였다. 제조된 필름의 전기전도성 측정은 부피저항과, 표면저항을 각각 측정하여 확인하였으며, 필름의 마찰 대전압은 E.S.T-7 마찰 대전압 시험기를 이용하여 표면 마찰 대전압과 반감기를 측정하여 확인하고, 필름의 물리적 특성은 인장시험기를 이용하여 breaking stress, breaking strain을 구하였다. 필름의 표면 특성은 영상 현미경 시스템을 사용하여 ${\times}1000$ 배율로 측정하여 분산특성과의 연관성을 확인하였다.

• Journal of Adhesion and Interface
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• v.22 no.4
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• pp.136-143
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• 2021

Polyurea has been investigated as a polymer matrix for composite materials because of its high mechanical strength. Although polyurea has a similar chemical structure to polyurethane, it has much higher strength and durability. In this study, the fabrication of polyurea composites reinforced with carbon nanotube (CNT) and graphene oxide (GO) is demonstrated to enhance the tensile strength of the glass fibers composite. Using FTIR and Raman spectroscopies, the chemical structures of polyurea, CNT, and GO are investigated. As a result, spectroscopy analysis reveals that the chemical structure of CNT, GO, and polyurea is maintained during the fabrication of the composite structure. Scanning electron microscopy reveals the uniform distribution of CNT and GO across the polyurea matrix. The reinforcement of 1 wt% CNT in polyurea enhances the tensile strength of CNT/polyurea composites. In contrast, the reinforcement of GO in polyurea induces the degradation of the tensile strength of GO/polyurea composites.