• Korean Chemical Engineering Research
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• 제49권2호
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• pp.211-217
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• 2011

본 연구는 high impact polystyrene (HIPS)의 가교 및 술폰화시간을 달리하여 이온교환막을 제조하였다. 술폰화 HIPS(SHIPS) 이온교환막의 술폰화도는 술폰화시간이 증가함에 따라 증가하였고, 가교시간이 증가함에 따라 감소하였으며 이때 최대 술폰화도는 66%였다. 또한, SHIPS 이온교환막의 이온교환용량과 함수율은 가교율이 증가할수록 감소하였고 술폰화시간이 증가할수록 우수한 성능을 나타냈으며 가장 우수한 함수율과 이온교환용량은 35.2%와 1.55 meq/g이였다. SHIPS 이온교환막의 전기저항 및 이온전도도는 술폰화시간이 증가할수록 우수한 성능을 나타냈으며 가장 우수한 값은 각각 $0.4\Omega{\cdot}cm^{2}$와 0.1 S/cm으로 나타났으며 Nafion 117보다 성능이 우수하였다. SHIPS 이온교환막의 유기용매에서의 내구성은 가교시간이 증가할수록 증가하였으며 SEM 관찰 결과 술폰화시간이 진행됨에 따라 표면이 불균일하게 변화되는 것을 확인할 수 있었다.

• 한국의류학회지
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• 제29권5호
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• pp.671-679
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• 2005

Chitosan is the affinitive finishing agent and gives susceptible effect in textile finishing. In order to examine the modification of polyester fabric treated with chitosan, we observed the characteristic of polyester fabric surface and measured its physical properties. For the purpose of confirming the adhesion of cationic material, we made a comparative study on anionic acid dye. The fabric was treated with crosslinking agent after chitosan finishing. Glutardialdehyde as crosslinking agent was used to improve the fixation rate of chitosan on the polyester fabric. And the US value was increased according to increasing of chitosan concentration. As the concentration of crosslinking agent was increased, whiteness index of the fabric chitosan treated was increased. Moisture regain of the fabric treated with $1\%$ chitosan was doubled and that treated with $2\%$ chitosan was tripled comparing with original fabric. Tensile strength of the chitosan treated fabric had been an increase of $10\%$ compared with alkali treated fabric and crease resistance decreased regardless of chitosan concentration.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1058-1060
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• 1995

In this paper, we studied the tracking characteristics of silicone rubbers that differed in the degree of crosslinking. As the tracking method, we adopted ASTM D 2303 and Merry-Go-Round(MGR) test method. It was found that the higher the degree of crosslinking, the better tracking characteristics. In these two test methods, specimens showed similar tendency of performance variation according to the degree of crosslinking. However the degradation phenomena were very different. As for MGR method, only the color of specimens' surface changed without any erosion or tracking path on them. On the contrary, the specimens subjected to ASTM D 2303 test method showed severe erosion.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
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• pp.435-438
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• 1991

This work is aimed to clarify the effect of only crosslinking of polyethylene on the water tree propagation and thus the crosslinking of LDPE was made by use of $Co^{60}$ $\gamma$-ray irradiation at room temperature. For this purpose, before water tree testing under same test conditions, injection molded samples were made of LDPE using CNRS laboratory model and also some of them were irradiated under different dose rate for crosslinking. Afterwards, the aged specimens were put into microscopic investigation as a mean to compare their different morphological aspects by use of SEM for the fractured surface. The SEM observation points out that the untreed region in the irradiated PE shows the densed structure whereas that in the LDPE is not closely packed. Also in the water treed region of LDPE, the density and the dimension of voids are higher than those in irradiated PE. Based on our results, it seems that the difference in the PE structure could sufficiently contribute to cause the different water tree propagation of these materials.

• 멤브레인
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• 제6권4호
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• pp.242-249
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• 1996

물/에탄올 수용액에 대한 투과증발특성을 개선하기 위하여 키토산을 이용하여 키토산/폴리비닐알콜 블렌드, 인산화 키토산 복합막을 제조하였다. 키토산과 폴리비닐알콜은 조성을 변화시키면서 블렌드를 얻을 수 있었으며, 글루탈알데히드를 이용하여 가교 방법과 조건을 변화시켜서 가교된 키토산/폴리비닐알콜 복합막을 제조하였다. 가교 농도와 가교 시간이 증가할수록 선택도는 증가하였으며 투과유량은 감소하였다. 글루탈알데히드를 가교제로서 키토산용액에 직접 첨가한 경우가 표면만을 가교한 경우보다 우수한 투과증발 성능을 나타내었다. 또한 인산화반응을 통하여 반응시간에 따라서 인산화도가 조절된 인산화 키토산을 얻었으며 이를 이용하여 인산화키토산 복합막을 제조하였다. 반응시간이 증가할수록 인함량이 증가하였으며 더불어 인산기의 도입에 따른 친수성의 증가로 선택도의 증가가 나타났다.

• 폴리머
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• 제26권6호
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• pp.778-784
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• 2002

덱스트란 용액으로 필름을 제조하여 여러 가지 특성들을 살펴보았으며, 가소제 및 가교제를 첨가하거나 저온 플라스마로 표면을 처리함으로써 이러한 특성들을 향상시킬 수 있는 지를 살펴보았다. 덱스트란 필름은 기계적 강도는 우수하였으나 부스러지기 쉽고 수분에 대단히 약한 특성을 보였다 가소제를 첨가할 경우에는 유연성이 크게 개선되는 대신에 기계적 강도가 크게 약화되었다. 하지만, 가소제를 첨가한 다음 가교제로 가교시키거나 함께 첨가할 경우에는 비교적 우수한 기계적 강도와 함께 유연성을 지닌 필름이 제조되었으며, 수분에 대한 저항성도 향상되었다. 또한, 아세틸렌 플라스마로 처리할 경우 필름 자체의 특성은 크게 변하지 않으나 친수성인 표면이 소수성으로 바뀌었다.

• Bulletin of the Korean Chemical Society
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• 제30권2호
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• pp.334-338
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• 2009

Trifunctional epoxy resin triglycidyl paraaminophenol (TGPAP)/$CaCO_3$ nanocomposites were prepared using the melt blending method. The effects of nano-$CaCO_3$ content on the thermal behaviors, such as cure behavior, glass transition temperature ($T_g$), thermal stability, and the coefficient of thermal extension (CTE), were investigated by several techniques. Differential scanning calorimetry (DSC) results indicated that the cure reaction of the TGPAP epoxy resin was accelerated with the addition of nano-$CaCO_3$. When the nano-$CaCO_3$ content was increased, the $T_g$ of the TGPAP/$CaCO_3$ nanocomposites did not obviously change, whereas the crosslinking density was linearly increased. The nanocomposites showed a higher thermal stability than that of the neat epoxy resin. This result could be attributed to the increased surface contact area between the nano-$CaCO_3$ particles and the epoxy matrix, as well as the high crosslinking density in the TGPAP/$CaCO_3$ nanocomposites. The CTE of the nanocomposites in the rubbery region was significantly decreased as the nano-$CaCO_3$ content was increased.

• 방사선산업학회지
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• 제9권2호
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• pp.77-84
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• 2015

The stainless steel mesh coated with poly(acrylic acid) hydrogel was fabricated and applied for the separation of water and oil. The stainless steel mesh was immersed in aqueous poly (acrylic acid) solution, and then irradiated by radiation to introduce poly(acrylic acid) hydrogel on the surface of mesh by crosslinking. It was possible to separate oil and water from mixtures of oil/water effectively using the hydrogel-coated mesh. The effect of irradiation dose, coating thickness, size of mesh on the separation efficiency was examined.

• 접착 및 계면
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• 제16권2호
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• pp.55-62
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• 2015

자외선 경화를 통한 2-EHA/AA 점착제 제조 시 나노 충전제로 실리카를 도입하는 경우 실리카의 표면 처리 여부와 실리카 함량이 점착제의 점착 물성 및 열 안정성에 미치는 영향을 조사하였다. 또한 서로 다른 반복단위 길이를 가진 경화제에 따른 실리카의 보강 효과 차이도 관찰하였다. 실란으로 표면 처리된 실리카의 경우 실리카 표면과 고분자 매트릭스 간 계면 상호 작용으로 고분자 매트릭스 내 분산 정도를 높여 겔 함량의 저하 없이 0.3 wt%의 농도까지 점착 물성을 증가시키는 것으로 확인되었다. 특히 경화제로 PEGDMA를 사용할 때 분자 내 상대적으로 긴 에틸렌옥사이드 반복단위에 기인하는 분자 유연성으로 EGDMA를 사용한 계에 비해 실리카 보강 역할에 더 긍정적인 것으로 나타났다. 또한 열 분해 후 잔존량을 통해 실리카와 고분자 간 강한 계면 결합으로 인한 열 장벽 효과로 점착제의 열 안정성이 향상되는 것을 알 수 있었다.

• Restorative Dentistry and Endodontics
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• 제41권4호
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• pp.296-303
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• 2016

Objectives: The purpose of the present study was to evaluate the effects of proanthocyanidin (PAC), a crosslinking agent, on the physical properties of a collagen hydrogel and the behavior of human periodontal ligament cells (hPDLCs) cultured in the scaffold. Materials and Methods: Viability of hPDLCs treated with PAC was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The physical properties of PAC treated collagen hydrogel scaffold were evaluated by the measurement of setting time, surface roughness, and differential scanning calorimetry (DSC). The behavior of the hPDLCs in the collagen scaffold was evaluated by cell morphology observation and cell numbers counting. Results: The setting time of the collagen scaffold was shortened in the presence of PAC (p < 0.05). The surface roughness of the PAC-treated collagen was higher compared to the untreated control group (p < 0.05). The thermogram of the crosslinked collagen exhibited a higher endothermic peak compared to the uncrosslinked one. Cells in the PAC-treated collagen were observed to attach in closer proximity to one another with more cytoplasmic extensions compared to cells in the untreated control group. The number of cells cultured in the PAC-treated collagen scaffolds was significantly increased compared to the untreated control (p < 0.05). Conclusions: Our results showed that PAC enhanced the physical properties of the collagen scaffold. Furthermore, the proliferation of hPDLCs cultured in the collagen scaffold crosslinked with PAC was facilitated. Conclusively, the application of PAC to the collagen scaffold may be beneficial for engineering-based periodontal ligament regeneration in delayed replantation.