• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.283-284
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• 2003

습식응고법에 의한 다공성 폴리우레탄-부직포 합성피혁은 일반적으로 DMF 또는 MEK 둥의 용제로 희석한 폴리우레탄 수지에 니들펀칭 부직포를 함침하여 기포를 준비한 후, 폴리우레탄으로 코팅하여 비용매인 물에서 응고하는 방법으로 제조한다. 따라서 합성피혁은 부직포의 물성, 함침조건, 코팅조건 및 응고조건에 따라 물성의 차이를 나타낼 것으로 판단된다[l]. 특히 합성피혁의 물성은 폴리우레탄 코팅층의 내부에 형성되는 셀(cell)의 크기, 분포 및 형태에 크게 의존한다. (중략)

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.41-41
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• 2012

고급 스포츠웨어와 이너웨어 등에 많이 사용되고 있는 나일론/폴리우레탄 혼방제품은 염색에 있어서 Grin-through 현상, 인공피혁의 염료 이염 현상 등 많은 문제들이 존재한다. 본 연구의 나일론과 폴리우레탄 복합소재에서 나타나는 염색거동을 고찰하고 분석하여, 폴리우레탄 복합소재의 염색성을 개선하기 위하여 실시하였다. 폴리우레탄 복합소재는 해성분이 용출되지 않은 나일론 초극세사 소재에 폴리우레탄 수지를 함침하여 인공피혁과 같은 느낌을 주도록 직접 제조하였다. 제조된 폴리우레탄 함침 나일론 초극세사 소재의 해성분을 용출하였고, Red 색상의 밀링형 산성 염료, 함금속 염료와 반응성 염료에 따라 달라지는 염색특성 및 세탁 견뢰도 등을 고찰하였다. 본 연구를 통하여 다음과 같은 실험결과를 얻을 수 있었다. 나일론 초극세사와 폴리우레탄 수지를 준비하여 습식공정을 통해 인공피혁을 제조한 함침 소재를 알칼리 감량하였고, 감량률은 15~17% 정도로서 대부분의 해성분이 용출됨을 확인하였다. PPG와 PTMG로 구성된 폴리올을 기반으로 한 폴리우레탄 함침 피혁과 PTMG를 단독으로 사용한 함침 피혁의 염색성을 비교한 결과, PPG+PTMG 타입이 더 우수한 염색성을 나타내었다. 특히 밀링 타입과 함금속 타입 염료의 경우는 거의 2배 이상의 흡진율과 겉보기 색농도를 나타내었다. 한편, 반응성 염료의 경우는 두 종류의 폴리우레탄 필름에 거의 염착되지 않았기 때문에 앞으로의 염색실험에서 제외하였다. 견뢰도 측면에서는 각각의 피염물의 등급은 거의 유사하게 나타남을 확인하였다. 이상과 같은 결과로부터, 인공피혁 제조시 PPG+PTMG 타입의 폴리우레탄 수지를 사용하여 함침시 더 높은 색강도와 염착률을 얻을 수 있음을 알았다. 사용하는 염료의 종류를 좀 더 다양하게 하여 실험을 실시하고 폴리우레탄의 물성 및 분석 등의 추가적인 연구가 진행된다면, 인공피혁의 염색시에 발생하는 여러 가지 문제점들을 해결할 수 있을 것이다.

• Applied Chemistry for Engineering
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• v.24 no.2
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• pp.121-125
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• 2013

In this work, we prepared the carbon paper from chopped carbon fibers using a gas diffusion matrix in polymer electrolyte membrane fuel cells by wet processing. The process of making carbon paper using wet processing is consisted of the three steps involving the dispersion of chopped carbon fibers, the preparation of the carbon fiber web, the impregnating of phenol resin. This work was focused on finding the optimal surfactant to make the carbon paper with 2D orientation of carbon fibers by investigating the dispersion state of carbon fibers in different dispersion solutions. Furthermore, the effect of phenol resin and carbon black contents on properties of electric conductivity was analyzed. As a result, it is confirmed that the carbon fiber was well dispersed when using sodium dodecyl sulfate as a surfactant, and the carbon paper with 8 wt% of phenol and 5 wt% of carbon black contents showed the most excellent electrical property.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.2
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• pp.129-136
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• 2017

Characteristics of $ZrO_2$ felt supported Cu/Zn catalysts have been investigated for the production of hydrogen via methanol steam reforming. Cu and Zn in different weight percent were loaded using wet impregnation over $ZrO_2$ felt support. The catalysts were characterized with BET and FE-SEM. The performance of these synthesized catalysts were investigated at SCR=1.5, $GHSV=2000h^{-1}$, temperature=$300{\sim}400^{\circ}C$, and pressure=2.5~19.5 barA. The results showed that the $Cu^{32.5}Zn^{7.5}ZrO_2$ catalyst was most active in terms of methanol conversion and hydrogen production. The methanol conversion in steam reforming of methanol was 84.6% at 19.5 barA and furnace $400^{\circ}C$ over $Cu^{32.5}Zn^{7.5}ZrO_2$ catalyst. The catalysts prepared using $ZrO_2$ felt show higher reactor temperature than the pellet type catalyst at same furnace temperature.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.435-441
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• 2017

Studies on self-healing have currently been diversified and the methods to evaluate the studies have become more diversified as well. Among them, the back-scattered electron (BSE) image acquired through the scanning electron microscope (SEM) is attempted as the means to evaluate the self-healing effect on cracks. In order evaluate by the BSE image, sophisticated pre-processing of specimen is critical and this injected inside the particle, pore and artificial crack of the hardener to stabilize the structure of the newly generated self-healing product and it enables to endure the stress on polishing without deformation. The impregnated specimen smoothen the surface to obtain the BSE image of high resolution that polishing is made for diamond suspension for wet polishing after dry polishing. As a result of evaluating the self-healing product on the impregnated and polished self-healing specimen, the generated product is formed from the surface of the artificial crack and the self-healing substances are confirmed as $Ca(OH)_2$ and C-S-H.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.5
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• pp.189-193
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• 2020

Recently, various methods for preparing a flexible electrode for implementing a wearable sensor have been introduced. Wearable sensors show similar tendency to use various polymer substrates, which provides elasticity suitable to the motion of human body. In this paper, a highly elastic silver nanowire based electrode was prepared on a sponge-based stretchable substrate, and electrical properties were evaluated. Silver nanowires were grown using a wet chemical synthesis, impregnated into a plasma-treated sponge, and then heat treated at a low temperature. In particular, the plasma surface treatment of the sponge enables uniform coating of silver nanowires. The flexible sponge electrode showed reliable electrical resistance changes over 160 repeated tensile-compression cycles.

• Clean Technology
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• v.28 no.4
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• pp.269-277
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• 2022

With the recent development of the biological enzymatic reaction industry, lactic acid (LA) can be mass-produced from biomass sources. In particular, a catalytic process that converts LA into acrylic acid (AA) is receiving much attention because AA is used widely in the petrochemical industry as a monomer for superabsorbent polymers (SAP) and as an adhesive for displays. In the LA conversion process, NaY zeolites have been previously shown to be a high-activity catalyst, which improves AA selectivity and long-term stability. However, NaY zeolites suffer from fast deactivation due to severe coking. Therefore, the aim of this study is to modify the acid-base properties of the NaY zeolite to address this shortcoming. First, base promoters, Ca ions, were introduced to the NaY zeolites to tune their acidity and basicity via ion exchange (IE) and incipient wetness impregnation (IWI). The IWI method showed superior catalyst selectivity and stability compared to the IE method, maintaining a high AA yield of approximately 40% during the 16 h reaction. Based on the NH₃- and CO₂-TPD results, the calcium salts that impregnated into the NaY zeolites were proposed to exit as an oxide form mainly at the exterior surface of NaY and act as additional base sites to promote the dehydration of LA to AA. The NaY zeolites were further treated with KOH before calcium impregnation to reduce the total acidity and improve the dispersion of calcium through the mesopores formed by KOH-induced desilication. However, this KOH treatment did not lead to enhanced AA selectivity. Finally, calcium loading was increased from 1wt% to 5wt% to maximize the amount of base sites. The increased basicity improved the AA selectivity substantially to 65% at 100% conversion while maintaining high activity during a 24 h reaction. Our results suggest that controlling the basicity of the catalyst is key to obtaining high AA selectivity and high catalyst stability.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.2
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• pp.94-101
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• 2017

Tow Prepreg is the intermediate material for filament winding process that has been "pre-impregnated fiber tow" with resin system. As "dry filament winding" process emerges as a reliable alternative to conventional filament winding (called "wet filament winding") process, interest in tow prepreg as a material for dry filament winding is rising as well. In this article, we have reviewed the recent research trends in carbon fiber tow prepreg for high-performance rocket motor cases, fuel tanks for hydrogen vehicles and other high-quality commercial pressure vessels.

• Clean Technology
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• v.17 no.2
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• pp.166-174
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• 2011

The xAl-yCe oxide catalysts with different mol ratios of Al/(Al+Ce) were prepared by a co-precipitation method and Pt supported on xAl-yCe oxide catalysts were synthesized by an incipient wetness impregnation method. The catalysts were characterized by X-ray Diffraction (XRD), $N_2$ sorption, and $H_2$/CO-temperature programmed reduction ($H_2$/CO-TPR) to correlate with catalytic activities in co oxidation. Among the catalysts studied here, Pt/1Al-9Ce oxide catalyst showed the highest activity in dry and wet reaction conditions and the catalytic activity showed a typical volcano-shape curve with respect to Al/(Al+Ce) mol ratio. When the presence of 5% water vapor in the feed, the temperature of $T_{50%}$ was shifted ca. $30^{\circ}C$ to lower temperature region than that in dry condition. From CO-TPR, the desorption peak of $CO_2$ on Pt/1Al-9Ce oxide catalyst showed the highest value and well correlated the catalytic performance. It indicates that the Pt/1Al-9Ce oxide catalyst has a large amount of active sites which can be adsorbed by co and easy to supplies the needed oxygen. In addition, the amount of pentacoordinated $Al^{3+}$ sites obtained through $^{27}Al$ NMR analysis is well correlated the catalytic performance.