• Membrane Journal
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• v.17 no.4
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• pp.311-317
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• 2007

Proton conducting crosslinked membranes have been prepared by polymer blending, which consist of poly(vinyl alcohol-co-ethylene) (PVA-co-PE) and poly(styrene sulfonic acid-co-maleic acid) (PSSA-co-PMA) at 50 : 50 wt ratio. Two kinds of PSSA-co-PMA copolymer with 3 : 1 and 1 : 1 the molar ratio of PSSA to PMA wereused as a proton conducting source. The ethylene content of PVA-co-PE was also changed as 0, 27 and 44 mol%. The membranes were thermally crosslinked via the esterification reaction between -OH of PVA and -COOH of PMA, as demonstrated by FT-IR spectroscopy (PVA-co-PE)/(PSSA-co-PMA) membranes with 3 : 1 the molar ratio of PSSA to PMA showed higher ion exchange capacity (IEC), lower water uptake and higher proton conductivity than those with 1 : 1 molar ratio. As the PE concentration increased, the IEC values, water uptake and proton conductivities decreased continuously. These properties were elucidated in terms of competitive effect between the concentration of sulfonic acid, hydrophilicity and the crosslinked structure of membranes.

• Resources Recycling
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• v.23 no.1
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• pp.48-57
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• 2014

In this study, we have investigated the influence of the nature of solvent on the grafting reaction of maleic anhydride onto polyethylene wax obtained as a by-product in a high density polyethylene plant. The results show that the grafting ratio in xylene as a solvent was higher than toluene. This is because xylene has excellent monomer solubility, swelling property and miscibility. It has been also observed that grafting degree shows an initial jump in percentage of grafting with increasing amount of solvent, from 0% v/w to 200% v/w giving maximum grafting in 200% v/w and then slightly decreases on further increase in the amount of solvent and becomes almost constant. It can be also seen that gel content was not formed under the use of solvent. It means that solvent prevented cross-linking reaction due to chain transfer reactions to solvent molecules. Studies of melt viscosity at $140^{\circ}C$ showed that viscosity increased after grafting of maleic anhydride onto polyethylene wax.

• Journal of the Korean Chemical Society
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• v.59 no.5
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• pp.413-422
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• 2015

Proton exchange membrane (PEM), which transfers proton from the anode to the cathode, is the key component of the proton exchange membrane fuel cell (PEMFC). Nafion is widely used as PEM due to its high proton conductivity as well as excellent chemical and physical stabilities. However, its high cost and the environmental hazards limit the commercial application in PEMFCs. To overcome these disadvantages, various alternative polymer electrolytes have been investigated for fuel cell applications. We used densely sulfonated polymers to maximize the ion conductivity of the corresponding membrane. To overcome high swelling, dipole-dipole interaction was used by introducing nitrile groups into the polymer backbone. As a result, physically-crosslinked membranes showed improved swelling ratio despite of high water uptake. All the membranes with different hydrophilic-hydrophobic compositions showed higher conductivity, despite their lower IEC, than that of Nafion-117.

• Journal of Energy Engineering
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• v.20 no.3
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• pp.171-177
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• 2011

PVA/GLA/$Al_2O_3{\cdot}3SiO_2$ composite membranes were prepared through the reaction polyvinyl alcohol (PVA) with glutaraldehyde (GLA) as a cross-linking agent and subsequently adding aluminum silicate ($Al_2O_3{\cdot}3SiO_2$) as an inorganic material. The water uptake decreased as the GDL contents increased due to cross-linking process of PVA with GDL, and the ion conductivity increased as the $Al_2O_3{\cdot}3SiO_2$ contents increased in PVA/GLA/$Al_2O_3{\cdot}3SiO_2$ composite membranes. The cross-linking structure of the polymers was confirmed using IR and the tendency of water uptake. The thermal analysis of the copolymers was carried out by TGA. TGA results showed that PVA/GLA composite membrane were more heat-resistant than PVA due to the cross-linking of PVA, and the heat stability of the composite membranes improved much more as the concentration of $Al_2O_3{\cdot}3SiO_2$ increased. Membranes prepared in this study seem to be have thermal stability and increase a tendency of the cation conductivity up to $60^{\circ}C$, but to be exhibit lower performance tendency at over $90^{\circ}C$. Therefore, it is necessary to do more aggressive effort to explore the possibility of application as an ion-conductive composite electrolyte.

• Polymer(Korea)
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• v.33 no.1
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• pp.39-44
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• 2009

Polymer substrates were fabricated by using poly (phenylene ether) as a base resin, N,N'-m-phenylenedimaleimide (PDMI) as a crosslinking agent and decabromodiphenylethane as a flame retardant. The effects of crosslinking agent and flame retardant on physical properties such as dielectric property of the substrate were investigated. Thermal curing feature of PDMI with or without an initiator was analyzed by DSC, and then, PPE-PDMI test compositions were designed based on this result. Composite sheets were cast by film coater, laminated under vacuum and pressure, and then, the changes of dielectric constant, dielectric loss, peel strength, solder heat resistance and inflammability according to increasing amount of PDMI and flame retardant were evaluated, Dielectric constant and dielectric loss showed increasing trend with increasing amount of PDMI and flame retardant, but solder heat resistance and inflammability were improved. Peel strength was obtained higher than 1 kN/m when PDMI above 10 wt% was added, but slightly decreased as the amount of flame retardant increased. From the measured gel contents, the reaction mechanism of PPE-PDMI system was deduced to the formation of network structure by crosslinking PDMI with PPE rather than the formation of semi-IPN structure. In conclusion, the polymer composite substrate materials with dielectric constant of 2.52$\sim$2.65 and dielectric loss below 0.002 at 1 GHz were obtained and they will be proper for high frequency applications.

• Clean Technology
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• v.19 no.4
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• pp.393-400
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• 2013

In this study, Polyethylene wax, which was produced in manufacturing process of high density polyethylene was grafted with maleic anhydride (MAH). The influences of reaction parameters on the graft polymerization as well as the effect of hydrolysis of the anhydride functions were investigated. The results show that the grafting degree increased and conversion of maleic anhydride decreased with an increase in MAH monomer content. This means the highest grafting efficiency for the reaction can be met when MAH monomer content is about 15 wt%. DCP (dicumyl peroxide) and DTBP (di-tert-butyl peroxide) have been used as the initiator and the highest yield of grafting was obtained when the initiator content is about 0.5 wt%. However, It can be seen that the gel content values of this polyethylene wax grafted MAH were below 2%. It was also observed that the grafting degree increased with an increase in reaction temperature and the maximum value was reached 2 hours later. Although MAH functions grafted onto polyethylene wax were mainly in the carboxylic acid forms, some anhydride form of MAH appeared in over 5% of grafting degree. As a result of hydrolysis reaction, it was observed that the conversion of anhydride group into carboxylic acid group was reached up to 10%.

• Membrane Journal
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• v.29 no.3
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• pp.173-182
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• 2019

Much research has been made for finding new and eco-friendly alternative sources of energy to solve the problems related with the pollution caused by emissions of greenhouse gases such as carbon dioxide as the use of fossil fuels increases worldwide. Among them, fuel cells draws particular interests as an eco-friendly energy generator because only water is obtained as a by-product. Anion exchange membrane-based alkaline fuel cell (AEMFC) that uses anion exchange membrane as an electrolyte is of increased interest recently because of its advantages in using low-cost metal catalyst unlike the PEMFC (potton exchange membrane fuel cell) due to the high-catalyst activity in alkaline conditions. The main properties required as an anion exchange membrane are high hydroxide conductivity and chemical stability at high pH. Recently we reported a chemically crosslinked poly(2-dimethyl-1,4-phenylene oxide) (PPO) by reacting PPO with N,N,N',N'-tetramethyl-1,6-hexanediamine as novel anion exchange membranes. In the current work, we further developed the same crosslinked polymer but having enhanced physicochemical properties, including higher conductivity, increased mechanical and dimensional stabilities by using the PPO with a higher molecular weight and also by increasing the crosslinking density. The obtained polymer membrane also showed a good cell performance.

• Journal of the Korean Chemical Society
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• v.56 no.1
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• pp.169-174
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• 2012

• Proceedings of the Membrane Society of Korea Conference
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• 1994.04a
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• pp.36-37
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• 1994

시판되는 방향족 폴리아미드계 역삼투막은 우수한 투과특성과 염배제율을 보이고 있다. 하지만 이들 막들은 내염소서의 결핍으로 염소소독시 분해되는 성질이 있어 역삼투특성의 급격한 저하가 일어난다. 이로인해 원수 처리시 전처리 과정으로써 염소살균처리를 하고, RO모듈 입구의 직전에 환원제를 주입하여 잔류염소를 제거하게되므로 공정상의 유지관리가 용이하지 않게된다. 역삼투특성이 우수한 폴리아미드막의 내염소성을 향상시키기 위해 트리메조일클리드를 이요한 가교, 강직한 작용기의 도입 및 친수성기와 소수성기의 고밀도 집적등의 방법으로 개질 폴리아미드막을 제조하는 연구결과들이 보고되었다.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.235-236
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• 2003

섬유의 습식 가공은 에너지 집약적 산업이다. 대부분의 에너지는 가공시 사용된 많은 양의 수분을 증발시키고, 건조하는데 소모되어진다. 따라서 거품가공은 물 소비를 감소시켜 에너지를 절약하고 폐수를 감소시키는데 주된 목적이 있다(1). 거품가공은 직물에 부가된 물의 양을 감소시켜 건조단계에서 상당한 에너지 소비(30~80%)를 감소시키는 것으로 알려져 있고(2~3), 최근에는 낮은 wet pick-up율에 의한 가공제 처리의 성능 및 수지의 가교분포에 대한 효과 등에 관한 많은 연구가 이루어지고 있으나 미흡한 점이 많이 보고되고 있다.(4~7) (중략)