• Carbon letters
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• 제16권1호
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• pp.62-66
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• 2015

In this study, carbonized fibers were prepared by using acidically cross-linked LDPE fibers. The surface morphologies of the carbonized fibers were observed by SEM. The effects of cross-linking process temperatures were studied using thermal analyses such as DSC and TGA. The melting and heating enthalpy of the fibers decreased as the cross-linking temperature increased. The cross-linked fibers had a carbonization yield of over 50%. From SEM results the highest yield of carbonized LDPE-based fibers was obtained by cross-linking at a sulfate temperature ($170^{\circ}C$). As a result, carbonation yield of the carbonized fibers was found to depend on the functions of the cross-linking ratio of the LDPE precursors.

• 분석과학
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• 제30권4호
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• pp.213-219
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• 2017

Polyalkylsiloxane has been spotlighted in pressure-sensitive adhesive (PSA) application due to excellent physical properties and good biocompatibility. Thermal behaviour of polyalkylsiloxane mixtures, such as thermal stability and heat flow, were studied using TG-DTA during catalytic hydrosilation. To understand reaction kinetics of cross-linking, catalytic hydrosilation of polyalkylsiloxane was monitored using variable temperature nuclear magnetic resonance (VT-NMR) as increased temperature. The formation of cross-linking bond $Si-CH_2-CH_2-Si$ was directly observed using distortionless enhanced by polarization transfer (DEPT) technique. Successfully polyalkylsiloxane PSA samples exhibited excellent adhesion properties by cross-linking reaction.

• 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.

• 전기학회논문지
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• 제61권9호
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• pp.1362-1367
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• 2012

High porous silica aerogel/polyurethane polymer composite was manufactured by cross-linking polymerization of polyurethane foaming process. The properties of microstructure, mechanical strength, and thermal properties were investigated for its various applications. The superhydrophobic silica aerogel powders were used for highly thermal insulation filler materials. The thermal conductivities can be resulted 0.07 W/mK to 0.13 W/mK, by decreasing the contents of silica aerogels in composite materials. It is found that the polymerization formulation by organic binders can be applied to heavy industires, building materials, and various industries.

• Macromolecular Research
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• 제16권3호
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• pp.189-193
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• 2008

Thermal cross-linking method of poly(vinyl alcohol) (PVA) using poly(acrylic acid) (PAA) was carried out on PVA/PAA hydrogels. The level of gelation was measured in the PVA/PAA hydrogels with various PAA contents. The swelling behavior at various pHs showed that the swelling kinetics and water contents of the PVA/PAA hydrogels reached equilibrium after 30 h, and the time to reach the equilibrium state decreased with increasing PAA content in the hydrogel. The water content increased with increasing pH of the buffer solution. The permeation and release of the drug were tested using indomethacin as a model drug. The permeated and released amounts of the drug increased with decreasing the PAA content because of the low free volume in the hydrogel due to the higher cross-linking density. The kinetic profile of drug release at various pHs showed that all samples reached the equilibrium state within the 5 h.

• Journal of Pharmaceutical Investigation
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• 제41권5호
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• pp.279-288
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• 2011

The Dexamethasone (DEX) loaded chitosan microspheres were prepared by thermal denaturation and chemical cross-linking method using a dierent concentration of glutaraldehyde as chemical cross-linking agent. The prepared microspheres were evaluated for the percentage of Drug Loading (DL), Encapsulation Efficiency (EE) and surface morphology by Scanning Electron Microscopy (SEM). DL and EE were found to be maximum range of 10.0 to 10.79 % and 58.19 to 64.73 % respectively. The SEM Photographs of the resultant microspheres exhibited fairly smooth surfaces and predominantly spherical in appearance. In addition, Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) shown that there was no interaction between the drug and polymer. In vitro and in vivo release studies revealed that the release of dexamethasone was sustained and extended up to 63 days and effectively controlled by the extent of cross-linking agent. Non-clinical parameters such as paw volume, hematological parameters like Erythrocyte Sedimentation Rate (ESR), Paced Cell Volume (PCV), Total Leucocytes Count (TLC), Hemoglobin (Hb), Differential Cell Count (DCC) were investigated in Fruend's Complete Adjuvant (FCA) induced arthritic rats. Radiology and histopathological studies were also performed in order to evaluate the therapeutic efficacy of the DEX-loaded microspheres in extenuating the rat arthritic model.

• 접착 및 계면
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• 제19권2호
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• pp.74-82
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• 2018

아크릴레이트 기반의 점착제를 가교 시키는 기술은 다양하게 소개되어 왔다. 본 연구에서는 에폭시 변성 단량체와 메틸아지리딘 가교제를 활용하여 높은 가교 밀도를 가지는 아크릴 구조체를 만들었다. 베이스구조체를 제조하기 위해서 빠른 제조 공정이 가능하고 무용제 공정이 가능한 UV 중합 기술을 활용했다. FT-IR, 경화거동 및 접착특성 평가를 통해 UV경화도 및 2차경화 온도에 따른 특성 변화를 확인하고자 하였다. 겔분율은 선경화 $800mJ/cm^2$, 120도 후 경화온도 조건에서 50%이상 확보할 수 있었으며, 180도 경화조건에서 80%이상 확보 할 수 있었다. 경화 시간이 길어짐에 따라 경화도가 100%에 도달하였으며 이를 통해 열경화를 통한 2차 경화가 효과적임을 확인 할 수 있었다.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1999년도 가을 한국섬유공학회 학술발표회 논문집(Proceedings of the Korean Textile Conference)
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• pp.509-512
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• 1999

• 폴리머
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• 제39권3호
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• pp.499-505
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• 2015

Dimethyldimethoxysilane(DMDMS), methyltrimethoxysilane(MTMS)과 phenyltrimethoxysilane(PTMS)을 이용하여 폴리유기실록산 열 경화성 코팅액을 제조하고 가교도와 페닐기 함량이 코팅액과 도막 물성에 미치는 영향을 살펴보았다. Si-NMR 측정에서 얻어진 D $T^{Me}$ $T^{Ph}$ 구조 코팅액 조성비가 사용된 DMDMS, MTMS, PTMS의 몰 비로부터 얻어진 이론치와 일치함을 확인할 수 있었다. 가교밀도가 높을수록 그리고 페닐 함량이 낮을수록 실록산 결합의 증가에 의하여 코팅액 분자량이 증가됨을 알 수 있으며 페닐기 증가는 코팅액 굴절률 증가에 매우 큰 영향을 미침을 알 수 있었다. 가교밀도가 높을수록, 페닐기 함량이 감소할수록 코팅도막 경도는 증가되었으며 내열특성 또한 우수해짐을 확인할 수 있었다. 이상의 결과로부터 같은 실록산 결합을 갖는 폴리유기실록산 코팅제라도 치환도에 따른 가교도 조절과 페닐기 함량에 따라 코팅액 물성이 달라짐을 확인할 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.715-718
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• 2000

We studied about electrical, chemical and mechanical characteristics of XLPE by dicumyl peroxide(DCP) and trimethylolpropane triacrylate(TMPTA) content ratio. DCP content was changed from 1.0 to 2.Sphr increasing 0.5phr. TMPTA content was changed 0.5 to 1.5phr increasing 0.5phr. Thermal analysis (DSC) was carried out in order to observe tendency of Tg according to DCP and TMPTA content. Tensile strength was measured in order to observe mechanical strength. In experimental results, content DCP 2.0phr and TMPTA 1.0phr has highest breakdown strength. Content DCP 2.0phr and TMPTA 0.5phr has lowest dielectric constant. Tendency of Tg did not affected by DCP and TMPTA content. Breakdown strength and Specific inductive capacity was measured.