• Transactions on Electrical and Electronic Materials
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• 제10권1호
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• pp.9-15
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• 2009

There is a growing demand for a high voltage silicone rubber composite with high mechanical property and high electrical property. The effect of modified cross-linking agent on the mechanical, electrical properties, and short-circuit test performance of silicone rubber insulators have been investigated. To use base polymer, the various silicone polymers were prepared by the equilibrium polymerization. Aluminum trihydrate surface was treated by vinyl silane. Liquid silicone rubber nanocomposite was prepared from the compounding of VPMPS, HPDMS, catalyst, and alumina trihydrate modified with 1,3,5-trivinyl-l,3,5-trimethylcyclotrisiloxane. The mechanical property and electrical property for insulation materials were measured, indicating the high tensile strength and the good short-circuit property.

• Macromolecular Research
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• 제14권1호
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• pp.34-37
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• 2006

Attaching the organosilyl groups to macromolecular chains of 2-hydroxyethyl methacrylate (HEMA) should lead to important modifications of polymer properties. t-$BuMe_{2}Si$ and cubane-l, 4-dicarboxylic acid (CDA) were covalently linked with 2-hydroxyethyl methacrylate (HEMA). The silyl-linked HEMA is abbreviated as TSMA, while cubane-l ,4-dicarboxylic acid (CDA) linked to two HEMA groups is the cross-linking agent (CA). Free radical cross-linking copolymerization of TSMA and HEMA with various ratios of CA as the cross-linking agent was carried out at 60-70$^{circ}C$. The compositions of the cross-linked, three-dimensional polymers were determined by FTIR spectroscopy. The glass transition temperature ($T_{g}$) of the network polymers was determined calorimetrically. The $T_{g}$ of the network polymer increased with increasing cross-linking degree.

• 멤브레인
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• 제28권3호
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• pp.205-213
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• 2018

본 연구에서는 가교막을 poly(2,6-dimethyl-1,4-phenylene oxide)(PPO)에 브롬화반응을 통해 제조한 Br-PPO를 주사슬로 성공적으로 제조하였고, 키토산과 4차암모늄이 포함된 키토산을 가교제로 사용하였다. 제조된 가교막은 트리메틸아민 용액에 함침하여 후처리를 진행하였다. 그리고 가교도는 가교제 비율을 이용하여 조절하였다. 이렇게 제조된 A-PPO + chitosan 가교막과 A-PPO + QA-chitosan 가교막의 이온교환막으로써의 가능성을 여러 특성평가로 확인하였다. Chitosan을 사용한 가교막보다 QA-chitosan을 사용한 가교막이 가교가 더 잘 이루어졌으며, QA-chitosan의 함량이 증가할수록 이온교환용량이 1.18 meq/g에서 1.53 meq/g까지 증가하는 경향, 함수율이 21.6%에서 42.2%까지 증가하는 경향을 나타내었다.

• 접착 및 계면
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• 제12권2호
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• pp.73-80
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• 2011

식물성 고분자인 대두단백질을 기반으로 하는 환경친화성 고분자 신소재에 관한 연구를 위해 가소제(1,3-propandiol, glycerol) 및 가교제(glutaraldehyde, epichlorohydrin, glyoxal, urea)에 의한 대두단백질 수지의 열적 특성을 TGA를 이용하여 분석하였고, 기계적 특성 분석과 SEM을 통하여 파단면을 관찰하였다. 그 결과, 가소제인 1,3-propandiol과 glycerol을 SPI (대두단백질)에 첨가함으로써 수지의 유연성이 증가하였고, 1,3-propandiol에 비하여 glycerol의 가소화 효과가 상대적으로 크게 나타났으며, 가교제인 glycerol, epichlorohydrin, glyoxal의 적용으로 첨가량이 증가할수록 대두단백질 수지의 강도와 열안정성이 증가하는 반면, urea의 경우, 대두단백과의 가교가 용이하지 않아 열안정성이 오히려 낮아지고, 강도가 감소함을 알 수 있었다.

• 한국응용과학기술학회지
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• 제26권3호
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• pp.263-268
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• 2009

Superporous Hydrogels (SPHs) have been extensively investigated for various biomedical applications due to their fast swelling and superabsorbent properties. In this study, glycol chitosan that is one of most abundant natural polymers was used as a cross-linking agent instead of bisacrylamide (BIS), which is a broadly used crosslinking agent for preparation of SPHs. Glycol chitosan was modified to have reactive vinyl groups by chemical conjugation with glycidyl methacrylate (GMA). The vinyl group-containing glycol chitosan (GC-GMA) was characterized by FT-IR and $^1H$-NMR measurements. SPHs have been prepared in various synthetic conditions to establish the optimum synthetic process for making superporous structure, where the inner pores are interconnected to each other to form a open channel structure. Various SPHs with different GC-GMA contents have been successfully prepared and have been observed to show faster swelling properties than other conventional SPHs. From the study on the swelling behavior of SPHs, the GC-GMA content is considered to be an important factor for controlling their swelling properties.

• Bulletin of the Korean Chemical Society
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• 제23권11호
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• pp.1616-1622
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• 2002

If the surfaces of vesicles are chemically modified so that they can be dispersed in organic solvents, the application of vesicular colloids may be expanded. A polymerizable surfactant (BDAC) and nonpolymerizable bipolar surfactant (BPAS) were synthesized in multi-steps. Large vesicles composed of BDAC and BPAS with embedded a cross-linking agent (divinylbenzene) underwent a radical polymerization. BPAS was extracted out using methanol (skeletonization). The headgroup of BDAC was cleaved off via hydrolysis in an acidic condition to yield vesicles where surfaces were covered with -COOH groups. There was no significant change in the overall shape. The skeletonized vesicles appear to have many holes with diameters up to about 25 nm. The holes retained even after hydrolysis. The hydrolyzed vesicles were not dispersed in water and most organic solvents such as tetrahydrofuran and chloroform, but dispersed in methanol.

• Advances in materials Research
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• 제11권3호
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• pp.191-209
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• 2022

Very slow degradation of synthetic based polymers has created a severe environmental issue that increased awareness towards research in polymers of biodegradable property. Soy protein isolate (SPI) is a natural biopolymer used as matrix in green composites but it has limitations of low mechanical properties and high water sensitivity. To enhance mechanical properties and reduce water sensitivity of Jute-SPI composites, SPI was modified with pine rosin which is also a natural cross-linking agent. 30% glycerol on the weight basis of a matrix was used as a plasticizer. The fibre volume fraction was kept constant at 0.2 whereas the pine rosin in SPI ranged from 5% to 30% of the matrix. The effects of pine rosin on mechanical, thermal, water sensitivity and surface morphology have been characterized using various techniques. The mechanical properties and water absorbency were found to be optimum for 15% pine rosin in Jute-SPI composite. Therefore, Jute-SPI composite without pine rosin and with 15% pine rosin were chosen for investigation through characterization by Fourier transforms infrared spectroscopy (FTIR), Thermo-gravimetric analysis (TGA), X-Ray diffraction (XRD) and Scanning electron microscope (SEM). The surface morphology of the composite was influenced by pine rosin which is shown in the SEM image. TGA measurement showed that the thermal properties improved due to the addition of pine rosin. Antimicrobial test showed antimicrobial property in the composite occurring 15% pine rosin. The research paper concludes that the modification of SPI resin with an optimum percentage of pine rosin enhanced mechanical, thermal as well as water-resistant properties of jute fibre reinforced composites.

• 청정기술
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• 제19권3호
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• pp.272-278
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• 2013

EPDM 고무는 여러 가지 용도에 많이 사용되고 있는 소재이다. 화력발전소의 소각로에서 부산물로 발생하는 버텀애쉬(bottom ash)는 플라이애쉬(fly ash)와는 달리 재활용이 거의 되지 않고 있는데, 본 연구에서는 버텀애쉬 및 탈크를 포함하는 EPDM 복합소재를 roll-mill을 이용하여 제조한 후, 기계적, 열적, 전기적 및 경화 특성 등을 분석하였다. 또한 주사전자현미경(scanning electron microscopy, SEM)을 이용하여 복합재료의 모폴로지를 관찰하였다. 일부의 버텀애쉬는 계면활성제를 이용하여 개질한 후 EPDM 복합재료를 제조하여 개질의 효과를 조사하였다. 결과로 개질된 버텀애쉬 및 탈크를 포함하는 EPDM 복합재료는 우수한 인장 강도 및 인장 탄성률을 나타내었다. EPDM 복합재료의 체적 저항은 $10^{14}{\Omega}cm$ 이상으로 전기 절연체로서 저항 임계치를 만족하였고, 열적 물성 결과 버텀애쉬 및 탈크가 EPDM의 열적 안정성을 높여 주는 것으로 확인되었다.

• Journal of Pharmaceutical Investigation
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• 제39권1호
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• pp.59-63
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• 2009

Soybean phosphatidylcholine microparticles loaded with cyclosporin A (CsA) were prepared by the modified emulsion solvent diffusion and ionic gelation method, in which chitosan on the surface of the microparticles was crosslinked with various concentrations of tripolyphosphate (TPP). The morphology of the particles was characterized by scanning electron microscopy (SEM). The change of particle size and zeta-potential by chitosan on the surface of the lipid microparticles were systematically observed. The encapsulation efficiency and loading capacity of CsA in the particles were determined by high performance liquid chromatography (HPLC). In vitro release kinetics was studied using the dialysis method. In the results, the mean particle size and the zeta-potential of lipid microparticles increased when the attached chitosan was cross-linked (from 2.5 to 6.2 ${\mu}m$ and from -37.0 to +93.0 mV, respectively). The cyclosporin A-loaded lipid microparticles appeared discrete and spherical particles with smooth surfaces. The encapsulation efficiency of CsA was between 79% and 90% while the loading capacity was between 41% and 56%. In vitro release study showed that the crosslinkage of chitosan by TPP significantly delayed the release of CsA from the particles in a concentration-dependent manner. Thus, the release of CsA from the lipid microparticles could be controlled by tripolyphosphate used as a cross-linking agent.