• Textile Coloration and Finishing
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• v.5 no.1
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• pp.19-25
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• 1993

Plastic optical fibers(POFs) composed of poly(methylmethacrylate) (PMMA), polystyrene (PS), or polycarbonate(PC) as a core materials, and of fluorinated polymer or PMMA as a cladding were fabricated and their properties were investigated in this study. The attenuation loss of PMAA core POF was about 1,700 dB/Km at 660 nm, the loss of PS core POF was 1,800 dB/Km at 560 nm, and the loss of PC core POF was 2,200 dB/Km at 780 nm. These attenuation losses of POFs prepared ill this study were higher than those of commerically available POFs. Compared to PMMA and PS core POFs, PC core POF has excellent characteristics, including high thermal stability, high flexibility, and high impact strength.

• Journal of Environmental Science International
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• v.11 no.12
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• pp.1315-1320
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• 2002

Since the enzymatic degradation of microbial poly[(R)-3-hydroxybutyrate-co-3-hydroxyvalerate] (P(3HB-co-3HV)) initially occurs by a surface erosion process, a degradation behavior could be controlled by the change of surface property. In order to control the rate of enzymatic degradation, plasma gas discharge and blending techniques were used to modify the surface of microbial P(3HB-co-3HV). The surface hydrophobic property of P(3HB-co-3HV) film was introduced by CF$_3$H plasma exposure. Also, the addition of small amount of polystyrene as a non-degradable polymer with lower surface energy to P(3HB-co-3HV) has been studied. The enzymatic degradation was carried out at 37 $^{\circ}C$ in 0.1 M potassium phosphate buffer (pH 7.4) in the presence of an extracellular PHB depolymerase purified from Alcaligenes facalis T1. Both results showed the significant retardation of enzymatic erosion due to the hydrophobicity and the enzyme inactivity of the fluorinated- and PS-enriched surface layers.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.5
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• pp.465-470
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• 2017

Sulfonated fluorinated block copolymers having diphenyl units were mixed with the sulfonated cationic conductive polymers at an optimum mixing ratio to form hybrid membranes for fuel cells and their characteristics were studied. 2D and 3D AFM topology analysis confirmed that the number of hydrophilic units in the hybrid membrane was improved. Through the FE-SEM, the microstructure of the hybrid membrane implied hydrogen bonding and pi-pi interactions, and EDAX confirmed carbon, oxygen, sulfur, and fluorine. The thermogravimetric analysis showed that the hybrid membrane was thermally stable and the hydrophilicity of the hybrid membrane was increased by the contact angle of water droplets. As a result, it was confirmed that the cation conductivity increased by a factor of 1.8 times as the number of acidic domains in the hybrid film increased.

• Macromolecular Research
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• v.17 no.6
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• pp.430-435
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• 2009

The effect of oxyfluorination temperature on the surface properties of carbon fibers and their reinforced epoxy composites was investigated. Infrared (IR) spectroscopy results for the oxyfluorinated carbon fibers revealed carboxyl/ester (C=O) and hydroxyl (O-H) groups at 1632 and 3450 $cm^{-1}$, respectively, and that the oxyfluorinated carbon fibers had a higher O-H peak intensity than that of the fluorinated ones. X-ray photoelectron spectroscopy (XPS) results indicated that after oxyfluorination, graphitic carbon was the major carbon functional component on the carbon fiber surfaces, while other functional groups present were C-O, C=O, HO-C=O, and $C-F_x$. These components improved the impact properties of oxyfluorinated carbon fibers-reinforced epoxy composites by improving the interfacial adhesion between the carbon fibers and the epoxy matrix resins.

• Membrane Journal
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• v.5 no.2
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• pp.65-73
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• 1995

Gore-Tex Membrane은 Ptfe(Polytetra Fluoroetylene)를 특수가공하여 극히 미세한 구조를 가지는 연속다공질체로 만들어 습건식용 산업용 여과재로 활용함으로써 그동안 사용되어 오던 종래의 심층여과방식의 여과포로서는 도저히 이룰 수 없었던 표면여과 기능을 갖춤에 따라 높은 집진효율이나 낮은 악력손실로 동시에 운전을 가능하게 한 새로운 첨단여과포로써 각종 산업분야에 이미 널리 적용되고 있다. 근래 Boiler, 소각로, 제철, 제강용로 등의 고온용 Bag Filter 소요가 증가됨에 따라 보다 효율적이고 경제적인 고온용 여과포에 대한 관심이 높아지고 있으며, 특히 소각로, 발전설비, Cement 생산공정 중 Kilin 공정 등에 주로 사용되어오던 전기 집진기 (Electrostatic Precipitator)의 집진효율이 Dioxine이나 Furan 등의 새로운 규제와 중금속, 혹은 분진들에 대해 강화되는 환경 규제치에 적응하기 어려워짐에 따라 Bag Filter로의 전환, 개선방안이 많이 연구되고 있으며 이미 활용되어지는 부분도 있는 바 이에 대한 새로운 적용방법 등을 소개하고자 한다.

• Proceedings of the Membrane Society of Korea Conference
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• 2005.11a
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• pp.215-218
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• 2005

• Membrane Journal
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• v.16 no.1
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• pp.16-24
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• 2006

We report on the preparation and characterization of sulfonated polymer membranes containing perfluorocyclobutane (PFCB) units and fluorene units. The polymers were prepared through three synthetic steps, that is, the synthesis of a trifluorovinylether-terminated monomer, its thermal polymerization, and post-sulfonation using chlorosulfonic acid. A series of sulfonated polymers with different ion exchange capacity (IEC) were prepared by changing the content of chlorosulfonic acid during the post-sulfonation reaction. All the synthesized compounds were characterized by FT-IR, $^{1}H-NMR,\;^{19}F-NMR$, and Mass spectroscopy. As the content of chlorosulfonic acid increased, the SD, IEC, water uptake, and ion conductivity of the sulfonated polymer membranes increased. The sulfonated polymer 4 showed higher values of ion conductivity than the Nafion-$115^{\circledR}$ in a wide range of temperatures ($25{\sim}80^{\circ}C$).

• Membrane Journal
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• v.21 no.1
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• pp.1-12
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• 2011

Partially fluorinated poly(arylene ether sulfone) block ionomer membranes with different branch degree for fuel cell applications were investigated. A sulfonable monomer, a non-sulfonable monomer and a trifunctional branching agent were synthesized and the sulfonable monomer was oligomerized to obtain block structures. The oligomer was then further polymerized with the non-sulfonable monomer and the branching agent. The mole ratio of oligomer : non-sulfonable monomer was fixed at 4:6 and the content of the branching agent was varied from 0 to 2 mol% (BBC-40Bx). Post-sulfonation of BBC-40Bx was carried out using chlorosulfonic acid (CSA) (SBBC-40Bx). All the synthesized compounds were characterized by $^1H$-NMR, $^{19}F$-NMR and FT-IR. It was confirmed that the ion exchange capacity (IEC), water uptake and ion conductivity of SBBC-40Bx increased with the increment of branching agent content.

• Polymer(Korea)
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• v.29 no.2
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• pp.172-176
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• 2005

Environmentally friendly water dispersion polyurethanes containing fluorine were prepared with a fluorinated polyol having $62\%$ of fluorine $(Fluorolink^{(R)}\;M_n\;1000)$. In order to control the fluorine contents of the synthesized polyurethanes polytetramethylene glycol (PTMG2000) and $Fluorolink^{(R)}$ were mixed at assigned ratios and reacted with isophorone diisocyanate (IPDI) as a diisocyanate used. Introducing hydrophilic anion to the polymer chain was achieved by applying dimethyl propionic acid (DMPA). The ionic groups were neutralized with triethyl amine (TEA) before dispersion into water. Chain extension was executed by adding ethylene diamine at the final stage. Mechanical properties of the polymers showed that modulus increased with increasing $Fluorolink^{(R)}$ content. Surface energy values obtained from contact angle measurement decreased with increasing $Fluorolink^{(R)}$ content up to $20\%$. We expect that the synthesized polyurethanes present reliable effect from the fluorine atoms incorporated even at a small amount of $Fluorolink^{(R)}$.

• Membrane Journal
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• v.17 no.4
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• pp.294-301
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• 2007

To improve oxidative stability of non-fluorinated styrene-based polymer electrolyte membranes, copolymerized membranes were prepared using styrene derivatives such as p-methylstyrene, t-butylstyrene, and ${\alpha}-methylstyrene$ by monomer sorption method. Prepared membrane was characterized by measurement of weight gain ratio, water content, ion-exchange capacity, proton conductivity, and oxidative stability under the accelerated condition. It was found that each step of monomer sorption method including sorption, polymerization and sulfonation could be affected by the properties and the structures of styrenederivatives. Due to difficulty of polymerization, ${\alpha}$-methylstyrene was copolymerized with styrene or p-methylstyrene. Prepared membrane using ${\alpha}-methylstyrene$ and styrene showed higher performance and stability comparing to copolymerized membrane with styrene. However, copolymerized membranes with ${\alpha}-methylstyrene$ did not showed much improved oxidative stability comparing to styrene membrane due to their lower molecular weight. The t-butylstyrene membrane showed a low performance due to substituted bulky-butyl group which prevents sorption and sulfonation reaction. However, copolymerized t-butylstyrene membranes with p-methylstyrene showed good performance and much improved stability than the styrene membranes.