• Applied Chemistry for Engineering
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• v.31 no.2
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• pp.226-229
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• 2020

N-phenylmaleimide (PMI), a compound for strengthening the heat resistance of ABS resin, is a yellow crystal. Therefore, copolymers modified with PMI exhibit color, which limits their use. In order to overcome such disadvantage, the demand for N-cyclohexylmaleimide (CHMI), which has similar properties to PMI and also is a white crystal, is increasing. However, CHMI is difficult to industrialize due to the formation of various by-products during synthesis, which requires an additional purification process resulting in a low yield. In this study, composite catalysts were developed to improve these problems and industrially produce CHMI. Finally, CHMI was synthesized with a 85% yield and at least 99.5% purity.

• Textile Coloration and Finishing
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• v.33 no.3
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• pp.161-167
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• 2021

Polymer nanocomposite is considered a great alternative to solve the limitations that exist in a simple combination material, as well as to produce multifunctional and high-performance results. In this research, PVA/bentonite nanocomposite films were prepared based on the presence or absence of modification of nano-clay(bentonite) a SUPERGEL^® product, modification conditions and content, and the structural variation of the prepared PVA/bentonite nanocomposite films were examined. The effect of variations in the internal structure of the nanocomposite on mechanical and thermal properties was investigated. As a result of evaluating the thermal characteristics of the PVA/bentonite nanocomposite film based on the concentration of the modified bentonite, it was verified that the thermal characteristics and stability were improved because of interaction between the polymer and the modified nano-clay.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.135.1-135.1
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• 2010

최근 고온에서 사용 가능한 PEMFC용 고분자전해질 막 개발에 대한 연구가 활발히 진행되고 있다. PEMFC가 고온에서 작동하게 되면 높은 성능과 많은 장점을 갖게 된다. PEMFC를 $100^{\circ}C$ 이상에서 운전하게 될 경우 백금 전극 반응을 향상시켜 고가의 백금 촉매 양을 줄일 수 있게 되고, 수소연료 속에 미량 포함된 CO에 의한 촉매표면 피독현상에 대한 내구성을 높일 수 있어 저 순도 수소연료 사용이 가능해 진다. 또한 가습장치와 수소 연료 개질장치의 부피를 줄일 수 있게 되어 전체적인 PEMFC 시스템이 단순화 된다. 현재 연료전지용 고분자 전해질막으로 DuPont사의 과-불소계 고분자 전해질막인 Nafion$^{(R)}$이 가장 널리 사용되고 있다. Nafion$^{(R)}$은 유연한 분자구조 안에 소수성이 강한 주사슬과 친수성을 나타내는 술폰산이 결합된 곁사슬이 존재하여 술폰화 곁사슬의 클러스터 둘레에는 친수성 영역이 형성이 되기때문에 소수/친수 상 분리가 잘되어 이온 클러스터 형성이 용이하지만 제조비용이 높은 단점을 갖고 있다. 특히, 전해질 막내에서 Bronsted base 역할을 하는 물에 의해 이온전도가 이루어지기 때문에 고온에서는 수분증발로 인해 성능이 급격히 감소된다. 따라서, 본 연구에서는 고온 저가습 조건에서 운전이 가능하고 Nafion이 갖는 문제점을 해결하고자, 내열특성이 뛰어나며 높은 수소이온 전도도 학보가 용이한 Sulfonated Poly(aryl ether)sulfone(SPAES) 고분자 전해질에, 고온에서도 수화성이 유지될 수 있도록 지르코니아를 황산화한 sulfated zirconia(s-$ZrO_2$)를 함침하여 복합 고분자전해질막을 제조하여 고온 저가습 조건에서의 수소이온 전도 특성에 관한 연구를 수행하였다. 개발된 막의 물리/화학적 특성은 water content(Wup%), 이온교환 용량(IEC, meq $g^{-1}$), 수소이온전도도(s $cm^{-1}$) 열 중량 분석(TGA), X선 회절분석(XRD) 등을 통하여 분석 및 관찰하였다. 내화학 및 열적 특성분석 결과, 황산화 반응공정으로 $ZrO_2$에 술폰산기가 안정적으로 결합하고 있음이 관찰되었으며, 본 연구에서 개발된 유 무기 복합막이 $250^{\circ}C$이상 열적안정성을 확보하고 있는 것으로 판단되었다. $100^{\circ}C$ 이하의 저온 영역에서, 일정 비율의 s-$ZrO_2$/SPAES막에서 이온교환용량(IEC)이 순수 SPAES 막보다 낮음에도 불구하고, water uptake가 증가함과 동시에 수소이온 전도도가 향상된 것을 관찰하였다. 또한, 고온에서는 수소이온이 자유롭게 이동할 수 있는 water channel을 형성하는 free water는 증발 하지만 s-$ZrO_2$와 SPAES의 술폰산기 사이에 강력하게 결합하고 있는 bound Water는 $100^{\circ}C$ 이상의 고온 영역에서도 존재하여, 비록 무가습 조건에서도 일정 비율의 s-$ZrO_2$/SPAES50 전해질 막의 경우, 높은 전도도를 나타냄을 관찰할 수 있었다. 따라서 본 연구를 통해 저가습 고온 적용을 목적으로 개발된 s-$ZrO_2$/SPAES50막은 우수한 내열 특성을 나타냄과 동시에 저가습 고온 영역($120^{\circ}C$, $50RH{\downarrow}$)에서 높은 수소이온 전도도를 유지하여, 고온 저가습 연료전지 운전에 적합할 것으로 사료된다.

• Polymer(Korea)
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• v.27 no.5
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• pp.458-463
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• 2003

The effect of ozone surface treatment of montmorillonite (MMT) was investigated in thermal stabilities of polypropylene (PP) nanocomposites. Sodium montmorillonite (Na$\^$+/-MMT) was organically modified with dodecylammonium chloride. The surface properties of MMT, including the specific surface area (S$\_$BET/), equilibrium spreading pressure ($\pi$$\_$e/), and London dispersive component (${\gamma}$s$\^$L/), were studied by the BET method with $N_2$ adsorption. Also, the thermal stabilities of the nanocomposites were investigated in DSC and TGA. As experimental results, $\pi$$\_$e/ and ${\gamma}$s$\^$L/ of the ozonized dodecylammonium chloride (DA-MK ( $O_3$)) were increased in about 1.7 and 3.5 mJ/ $m^2$, resulting from the increasing of the micropores. From the DSC results, it was found that the melting temperature and crystallization temperature of PP/DA-MK and PP/DA-MK ( $O_3$) were higher that those of pure PP. These results were explained that dodecylammonium chloride of nano-scale led to a nucleation effect for PP crystallization. Also, it was found that E$\_$t/ of the PP/DA-MK ( $O_3$) nanocomposies was increased within about 64 kJ/mol. These results were probably explained by the improvement of dispersivity of DA-MK ( $O_3$) in a PP matrix.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.458-464
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• 2006

The Pd-Ni-Ag alloy composite membrane using modified porous stainless steel (PSS) as a substrate was prepared by a electroless plating technique. In this work, we have introduced the intermediate layer between Pd-based alloy and a metal substrate. As an intermediate layer, the mixtures of nickel powder and inorganic sol such as $SiO_{2}$ sol, $Al_{2}O_{3}$ sol, and $TiO_{2}$ sol were used. The intermediate layers were coated onto a PSS substrate according to various membrane preparation conditions and then $N_{2}$ fluxes through the membranes with different intermediate layers were measured. The surface morphology of the intermediate layer in the mixture of nickel powder and inorganic sol was analyzed using scanning electron microscope (SEM). Finally, the Pd-Ni-Ag alloy composite membrane using the support coated with the mixture of nickel powder and silica as an intermediate layer was fabricated and then the gas permeances for $H_{2}$ and $N_{2}$ through the Pd-based membrane were investigated. The selectivity of $H_2/N_2$ was infinite and the $H_{2}$ flux was $1.39{\times}10^{-2}mol/m^2{\cdot}s$ at the temperature of $500^{\circ}C$ and trans-membrane pressure difference of 1 bar.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.30 no.1
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• pp.1-14
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• 2024

As awareness of environmental issues continues to grow, there is an escalating demand for recycling and repurposing byproducts of agricultural and food production processes and their conversion to high-value products. Coffee is the most widely consumed beverage globally; during coffee beverage processing and consumption, byproducts such as coffee silverskin (CS), spent coffee grounds (SCGs), and oil are generated. Despite containing beneficial materials such as cellulose, hemicellulose, lignin, lipids, and bioactive substances, these byproducts are typically discarded in landfills or incinerated. The utilization of CS, SCGs, and oil in the development of packaging materials holds significant potentials toward the realization of a sustainable society. To this end, considerable research efforts have been dedicated to the development of high-value materials derived from coffee byproducts, including functional fillers, polymer composites, and biodegradable polymers. Notably, CS and SCGs have been employed as functional fillers in polymer composites. Additionally, lipids extracted from SCGs have been used as plasticizers for polymers and cultured with microorganisms to produce biodegradable polymers. This review focuses on the research and development of polymer/CS and polymer/SCG composites as well as cellulose extraction and utilization from CS and SCGs and its applications, oil extraction from SCGs, and cultivation with microorganisms using extracted oil for polyhydroxyalkanoates(PHA) production.

• Journal of the Korean Ceramic Society
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• v.41 no.12 s.271
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• pp.929-932
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• 2004

It is known that small amount of MgO in excess is often added to develop pure perovskite single phase of PMN-based composite, however, extra MgO precipitates in grains and inhibits densification of PMN. In this study PMN-PT-BT (PBT) powder was prepared by a conventional mixed oxide method using $(MgCO_3)_4{\cdot}Mg(OH)_2{\cdot}5H_{2}O$ instead of MgO. The precursor was heated at $500^{\circ}C/1h$ and its surface was modified with MgO sol. This effect was investigated in the aspects of sintering and dielectric properties. Small amount of added MgO sol ($0.5{\sim}1.0wt\%$) enhanced sintering substantially below $1000^{\circ}C$. The PBT with $0.5wt\%$ MgO sol sintered at $900^{\circ}C/2h$ had density of $7.62\;g/cm^3$, room temperature dielectric constant of 14800, loss of dielectric constant of $1.1\%$, which were comparable to those of the PBT sintered at $1000^{\circ}C/2h$. It was noticeable that the extra MgO precipitated mostly on triple points and grain boundaries and resulted in inhibition of grain growth.

• Korean Chemical Engineering Research
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• v.47 no.4
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• pp.418-423
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• 2009

MWCNT(multi-wall carbon nanotube)-doped PEDOT:PSS(poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)), used as a HIL(hole injection layer) material in OLEDs(organic light emitting diodes), was spin-coated on to the ITO glass to form PEDOT:PSS-MWCNT nano composite thin film. Morphology and transparency characteristics of nano composite thin films with respect to the loading percent of MWCNT have been investigated using FT-IR, UV-Vis and SEM. Furthermore, ITO/PEDOT:PSS-MWCNT/NPD/$Alq_3$/Al devices were fabricated, and then J-V and L-V characteristics were investigated. Functional group-incorporated MWCNT was prepared by acid treatment and showed good dispersion property in PEDOT:PSS solution. PEDOT:PSS-MWCNT thin films possessed good transparency property. For multi-layered devices, it was shown that as the loading percent of MWCNT increased, the current density increased but the luminance dramatically decreased. It might be conclusively suggested that the enhanced charge mobility by MWCNT could increase the current density but the hole trapping property of MWCNT could dramatically decrease the hole mobility in the current devices.

• Polymer(Korea)
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• v.37 no.4
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• pp.494-499
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• 2013

Modified polypropylene (m-PP) was fabricated by furfuryl sulphide (FS) as branching agent and m-PP/nano-filler composites were prepared with silicate and multi-walled carbon nanotube (MWCNT), using a twin screw extruder. The chemical structures and thermal properties of the m-PP were investigated by FTIR and DSC. The chemical structure of the m-PP was confirmed by the existence of =C-H stretching peak of the branching agent at 3100 $cm^{-1}$. There was no district change in melting temperature in case of m-PP, but a certain increase in crystallization temperature was notified and the increase was in the range of $10-20^{\circ}C$. The rheological properties, filler dispersion and foaming behaviors of the m-PP/nano-filler composites were investigated by dynamic rheometer, X-ray diffractometer (XRD) and scanning/transmission electron microscope (SEM/TEM). m-PP/nano-filler composites showed a high complex viscosity at a low frequency, an increase in melt elasticity, and a high shear thinning effect. Compared to pure PP, m-PP and m-PP/nano-filler composites were sufficient to enhance the foaming behavior.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.2
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• pp.81-86
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• 2011

Polymer-modified cement is the composite material made by partially replacing and strengthening the cement hydrate binders of conventional mortar with polymeric modifiers such as polymer latexes and redispersible polymeric modifiers. It is known that the addition of polymer to cement mortar leads to improved quality, which would be expected to have a high chemical resistance. Therefore, the purpose of this study is to identify the improved chemical resistance, such as low permeability and low ion diffusivity, of the polymer-modified cement as a solidification agent for the radwaste. First, polymer-modified cement specimens by latex modification were prepared according to the polymer content from 0% to 30% to select the optimized polymer content. At those specimens, the water-to-cement (W/C) ratio was maintained to 33% and 50% respectively. After the much curing time, the structural integrity of specimens was evaluated through the compressive strength test and the porosity evaluation by the water immersion method. From the results, 10% of the polymer content at 33% of the W/C ratio was shown to have the most improved quality. Finally, the leaching test referredfrom ANS 16.1 for the specimens having the most improved quality was conducted. Dedicated specimens for the leaching test were then mixed with radioisotopes of $^{60}Co$ and $^{137}Cs$ at the specimen preparation.