• Macromolecular Research
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• 제11권3호
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• pp.163-171
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• 2003

For the pervaporation of water-ethanol mixtures, new composite membranes having poly(acrylic acid)-poly (butyl methacrylate-co-methyl methacrylate) interpenetrati ng polymer network [PAA-P(BMA-co-MMA) IPN] skin layer supported on porous and crosslinked poly(BMA-co-MMA) were prepared. The morphology of the sub-layer of the composite membrane prepared in the presence of 60 wt% solvent showed cellular structure, on the other hand that of sublayer prepared in the presence of 70 wt% solvent presented very porous interconnected pore structure with macrovoids. Permeation rates of the composite membranes were largely influenced by the morphology of the sublayer. Separation factors increased with the increase of the degree of crosslinking of the PAA network. It was found that permeation rates could be increased by introducing anionic charges on carboxyl groups of the PAA. The permeation rate changes of the PAA-P(BMA-co-MMA) IPN composite membranes according to the feed compositions showed quite similar pattern with the swelling behavior in water-ethanol mixtures.

• 한국응용과학기술학회지
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• 제25권4호
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• pp.459-468
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• 2008

Methyl methacrylate(MMA) was grafted onto microcrystalline cellulose(MCC) with ceric ammonium nitrate(CAN) as a redox initiator at the various conditions. The cellulose triacetate(CTA) composite films added MCC and MMA-grafted MCC powders were prepared on a glass plate. The graft yield(GY) and graft efficiency(GE) of the grafted MCC were calculated with the simple equations by the weight balance method. The double bond of C=O on the grafted MCC surfaces was confirmed by the fourier transform infrared spectroscopy with attenuated total reflection(FT-IT ATR) spectrophotometer. After grafting, the degree of crystallinity of cellulose powders was decresed by judging from x-ray diffraction(XRD) data. Scanning electron microscope(SEM) photos showed the only solvent and CAN solution could change the roughness of MCC powders and the effect of powder dispersions in composite matrix. The tensile strength of MCC/CTA composite films was decreased with increase of MCC powder contents. When 5% grafted MCC was added, the tensile strength of grafted MCC/CTA composite films was increased from 82.3 MPa to 97.2 MPa. The thermal property of powders was also analyzed by the thermogravimetric analysis(TGA).

• Korean Membrane Journal
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• 제9권1호
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• pp.57-63
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• 2007

Amphiphilic graft copolymer from poly(vinylidene fluoride) (PVDF) was synthesized using atom transfer radical polymerization (ATRP) for composite nanofiltration membranes. Direct initiation of the secondary fluorinated site of PVDF facilitates grafting of tert-butyl methacrylate (tBMA). Amphiphilic PVDF-g-PMAA graft copolymer with a 51:49 wt ratio was obtained by hydrolyzing poly(tert-butyl methacrylate) (PtBMA) to poly(methacrylic acid) (PMAA). Wide angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC) confirmed the decrease of crystallinity of PVDF upon graft copolymerization. Composite nanofiltration membranes were prepared from PVDF-g-PMAA as a top layer coated onto PVDF ultrafiltration (UF) support membrane. The morphology and hydrophilicity of membranes were characterized using scanning electron microscopy (SEM) and contact angle measurement. The rejections of composite membranes were 80.2% for $Na_2SO_4$ and 28.4% for NaCl, and the solution flux were 9.5 and $14.5\;L/m^2\;h$ at 1.0 MPa pressure.

• 폴리머
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• 제29권4호
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• pp.380-384
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• 2005

Sodium montmoillonite 혹은 sodium montmorillonite가 삽입된 macromer의 존재 하에서 fluoroalkyl methacrylate와 아크릴산을 라디칼 공중합하여 불소화 아크릴계 이온성 고분자/sodium montmorillonite 복합재료를 제조하고, 이들의 X-선 회절 특성, 인장물성, 수분흡수율 등 물리적 성질을 조사하였다. 또, 이들을 이용하여 이온성 고분자-백금 복합재료(IPMC)를 제조하여 수 볼트의 외부 전위에 의한 전류 흐름 및 변위 거동을 측정한 결과, sodium montmorillonite가 이온의 이동을 방해하여 전류 및 변위량의 감소를 초래함을 관찰하였다.

• 폴리머
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• 제39권2호
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• pp.329-337
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• 2015

본 연구에서는 다중벽 탄소나노튜브(MWCNTs)를 질산과 황산의 혼산으로 산화시켜 표면에 카르복시기를 도입 후, $SOCl_2$와 1,4-butanediol을 사용하여 MWCNT-OH를 제조하였다. 제조된 MWCNT-OH는 3-methacryloxypropyltrimethoxylsilane(MPTMS)와 실란화 반응으로 methacrylate기가 도입된 MWCNT-MPTMS를 제조하였다. MWCNT-MPTMS와 methyl methacrylate(MMA)를 사용하여 유화중합법으로 MWCNT-MPTMS/PMMA 복합 입자를 제조하였다. 음이온 계면 활성제인 sodium dodecylbenzene sulfonate(SDBS)를 사용하여 유화중합한 MWCNT-MPTMS/PMMA는 균일한 입도, 좁은 입도분포 및 계면에서의 화학결합으로 인하여 $T_g$가 순수 MWCNT를 사용하여 중합한 시료보다 $3.4^{\circ}C$ 높아짐을 확인하였다.

• Restorative Dentistry and Endodontics
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• 제39권3호
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• pp.172-179
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• 2014

Objectives: This study aimed to assess the effect of 38% carbamide peroxide on the microleakage of class V cavities restored with either a silorane-based composite or two methacrylate-based composites. Materials and Methods: A total of 96 class V cavities were prepared on the buccal surface of extracted human teeth with both enamel and dentin margins and were randomly assigned into three groups of Filtek P90 (3M-ESPE) + P90 system adhesive (3M-ESPE)(group A), Filtek Z250 (3M-ESPE) + Adper Prompt L-Pop (3M-ESPE)(group B) and Filtek Z350XT (3M-ESPE) + Adper Prompt L-Pop (group C). Half of the teeth were randomly underwent bleaching (38% carbamide peroxide, Day White, Discus Dental, applying for 15 min, twice a day for 14 day) while the remaining half (control) were not bleached. Dye penetration was measured following immersion in basic fuchsine. Data were statistically analyzed using Kruskal-Wallis and Mann-Whitney U tests at a level of 0.05. Results: No significant differences were found between composites in the control groups in enamel (p = 0.171) or dentin (p = 0.094) margins. After bleaching, microleakage of Z250 (in enamel [p = 0.867] or dentin [p = 0.590] margins) and Z350 (in enamel [p = 0.445] or dentin [p = 0.591]margins) did not change significantly, but the microleakage of P90 significantly increased in both enamel (p = 0.042) and dentin (p = 0.002) margins. Conclusions: No significant differences were noted between the bleached and control subgroups of two methacrylate-based composites in enamel or dentin margins. Microleakage of silorane-based composite significantly increased after bleaching.

• Elastomers and Composites
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• 제50권2호
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• pp.110-118
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• 2015

In this study, diethylaminoethyl methacrylate-styrene-butadiene terpolymer (DEAEMA-SBR), in which diethylaminoethyl methacrylate (DEAEMA) was introduced to the SBR molecule as a third monomer, was synthesized by cold emulsion polymerization. It is expected that amine group introduced to a rubber molecule would improve dispersion of silica by the formation of hydrogen bond (or ionic coupling) between the amine group and silanol groups of silica surface. The chemical structure of DEAEMA-SBR was analyzed using proton nuclear magnetic resonance spectroscopy (H-NMR), Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). Then, various properties of DEAEMA-SBR/silica composite such as crosslink density, bound rubber content, abrasion resistance, and mechanical properties were evaluated. As a result, bound rubber content and crosslink density of DEAEMA-SBR/silica compound were higher than those of the SBR 1721 composite. Abrasion resistance and moduli at 300% elongation of the DEAEMA-SBR/silica composite were better than those of SBR 1721 composite due to the high bound rubber content and crosslink density. These results are attributed to high affinity between DEAEMA-SBR and silica. The proposed study suggests that DEAEMA-SBR can help to improve mechanical properties and abrasion resistance of the tire tread part.

• Composites Research
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• 제35권6호
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• pp.419-424
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• 2022

Using non-biodegradable polymers is a severe environmental problem as they are not recyclable and generate a large amount of waste. Biopolymers, such as starch-based composites, have been considered one of the most promising replacement materials. These eco-friendly materials have the advantage of being low-cost, biodegradable, and obtained from renewable sources. However, as starch tends to be brittle and hydrophilic, it can make these materials unusable when exposed to water and limit its processability for further applications. In this work, a biobased modified starch was grafted using two bioderived materials, lauryl methacrylate (LMA) and tetrahydrofurfuryl methacrylate (THFMA), by radical polymerization. A polylactic acid (PLA) composite based on the modified starch (m-St) was fabricated to enhance its toughness. These samples were characterized by Fourier transform infrared, ¹H NMR and ¹³C NMR analysis, optical and scanning electron microscopy. The starch was successfully grafted, thus improving the compatibility with the PLA matrix. The mechanical properties of these films were also studied. Results from mechanical tests showed a slight enhancement of the mechanical performance of these composites when m-St was added to the PLA matrix. Such behavior is related to the improved dispersion of m-St 1:2 on PLA, confirmed by SEM images showing enhanced compatibility between modified starch and PLA matrix. This indicated excellent properties of the produced composite film for further eco-friendly applications.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.29-32
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• 2003

Multi -walled carbon nanotube(MWNT)/poly(methyl methacrylate) composites were fabricate d through film casting. Manufacturing process was established using a ultrasonic cleaner and a homogenizer. Acetone was used as a solvent to melt PMMA and mix with MWNT. The ultrasonic cleaner performed an important role in producing MWNT/MMA nanocomposites. Ultrasonic energy was utilized to disperse MWNT in acetone. Also, melting PMMA in acetone and mixing MWNT and PMMA were achieved using the homogenizer. It was confirmed that the nanohlbes were well dispersed in PMMA according to SEM images.

• 대한치과기공학회지
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• 제28권1호
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• pp.43-52
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• 2006

Three t-amines, 4-(dimethylamino)benzoic acid (ABA), 4-(dimethylamino)benzaldehyde (MBA), 4-(dimethylamino)benzophenone (MBP), were investigated as new visible light photoinitiators for a dental resin composite of UDMA in order to improve photopolymerization effect. Three t-amines mixed with three photosensiizers, CQ, PD and DA, respectively. And the photopolymerization effect of photoinitiators were compared with that of 4-(dimethylamino)ethyl methacrylate (AEM), the most widely used photoinitiator. The photopolymerization efficiency of UDMA containing the photoinitiator increased with irradiation time. The increase was in the order: MBP