• Composites Research
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• v.32 no.6
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• pp.314-318
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• 2019

A simple and very flexible automatic dipping machine was constructed for producing functional multilayer films on wide substrates via the layer-by-layer (LbL) assembly technique. The proposed machine exhibits several features that allow a fully automated coating operation, such as various depositing recipes, control of the dipping depth and time, operating speed, and rinsing flow, air-assist drying nozzles, and an operation display. The machine uniformly dips a substrate into aqueous mixtures containing complementary (e.g., oppositely charged, capable of hydrogen bonding, or capable of covalent bonding) species. Between the dipping of each species, the sample is spray cleaned with deionized water and blow-dried with air. The dipping, rinsing, and drying areas and times are adjustable by a computer program. Graphene-based thin films up to ten-bilayers were prepared and characterized. This film exhibits the highly filled multilayer structures and low thermal resistance, indicating that the robotic dipping system is simple to produce functional thin film coatings with a variety of different layers.

• Elastomers and Composites
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• v.44 no.2
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• pp.122-133
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• 2009

Rubbers, such as natural rubber, polybutadiene, styrene-butadiene rubber, nitrile-butadiene rubber, chlorinated rubber and EPDM, have been continuously improved in response to a heavy demand and a new property requirement from industry. One of the best ways to realize the improvement is the modification of rubbers through chemical reactions, which produce materials with novel properties. In this review, chemical modification reactions of rubbers that contain carbon-carbon double bond units either in their main backbone or as a side group were briefly summarized. The chemical reactions introduce functional groups or functional polymer chains to polymer backbone, which transform a classical rubber to a highly functional material. Especially, we focused on a controlled/"living" radical polymerization techniques, with which a revolutionary broadening of the spectrum of the materials with well defined molecular weight, molecular weight distribution, chain end-functionality and architectures become possible.

• Elastomers and Composites
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• v.47 no.2
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• pp.162-167
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• 2012

Surface modification of macromolecules renders a progressive and favorable method to enhance the properties of polymeric materials and improves conductivity, wettability, stability, adhesion, antibacterial properties, etc. of polymeric surfaces without deterioration of the polymer bulk properties. Polyolefins such as polyethylene and polypropylene were grafted with maleic anhydride(MAH) as a functional monomer in solution. Evidence for grafting was shown with FTIR measurement. The grafting ratio was determined from chemical titration. The higher MAH loading, the lower contact angle(${\theta}$) was obtained. With the increasing content of MAH, melting temperature($T_m$) of maleic anhydride grafted polymer decreased while decomposition temperature($T_d$) of maleic anhydride grafted polymer increased.

• Elastomers and Composites
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• v.44 no.3
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• pp.209-221
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• 2009

Polyolefins are important commodity polymers with the largest volume of business owing to their outstanding combination of cost performance and excellent physical properties. However, the lack of functional groups often has limited their end uses, such as compatibilizer, modifier and adhesive, where the interaction with other materials is especially important. The incorporation of functional groups as polymer segments to afford block or graft polyolefin copolymers has been extensively investigated in the context of the functional polyolefin hybrids. Living polymerization processes have been considered to be an efficient method to prepare the polyolefin hybrids with precisely controlled architecture and compositions. Among the living polymerization techniques, controlled/"living" radical polymerization (CRP) methods are very effective not only because of the controllability of polymerization but also because of the versatility of monomers and polymerization conditions. In this review paper, progresses on the preparations of polyolefin graft or block copolymers through CRP techniques are summarized. The commodity polymers such as polyisobutylene, polyethylene and polypropylene are combined with polar segments such as polyacrylate, polymethacrylate, polystyrene to yield functionalized polyolefins.

• Elastomers and Composites
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• v.59 no.2
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• pp.64-72
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• 2024

As air pollution continues to increase owing to increasing traffic centered in urban areas, the tire industry is researching methods to reduce particulate matter. In this study, functionalized lithium butadiene rubber (F-LiBR) was applied to a natural rubber (NR)/butadiene rubber (BR) blend compound often used in truck bus radial (TBR) tire treads. The effect of the functional group that can react with carbon black (CB) in BR was investigated in terms of the dispersion of CB and the compound performance, including the generation of particulate matter. Compounds that were substituted with F-LiBR exhibited enhanced interaction with CB, resulting in excellent filler dispersion. Although F-LiBR exhibited lower crosslinking density and inferior abrasion resistance due to its high vinyl content, the compound with 30 phr of F-LiBR was advantageous in terms of its rolling resistance due to the excellent filler dispersion, which was also effective in reducing the amount of generated particulate matter (up to 56% reduction for PM_2.5, and 67% reduction for PM₁₀). The results confirmed the benefits of the introduction of functional groups into TBR tire tread compounds, which can aid in improving the fuel efficiency and reducing particulate matter generation.

• Elastomers and Composites
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• v.29 no.3
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• pp.226-233
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• 1994

The properties of the mixed prepolymer-urethane in the range of 10-40 phr were observed. LBR and LCR have same functional group but different in structure of molecular. The viscosity of mixture depending on content of rubber, adhesive strength, thermal property and compatibility with a diluted solvent are as follows: 1. The viscosity of the mixture was influenced by solubility of the diluent for urethane resin and liquid rubber. 2. Adhesive strength showed the highest value at 30phr rubber, decreased gradually at above 30phr rubber. And LBR revealed better physical property than that of LCR. 3. The most effective factors affecting adhesive strength are molecular structure of rubber, the type of solvent, and volatility. 4. Urethane resin containing LBR showed better compatibility for solvent and faster drying velocity. 5. LBR showed more favorable compatibility and dispersion state than those of LCR by analyzing the results of SEM.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.376-376
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• 2016

Poly(ethylene oxide) (PEO)/functionalized bacterial cellulose nanowhiskers (f-BCNW) (0.1 wt%) composite nanofibers were fabricated by electrospinning process and the thermomechanical properties were significantly enhanced more than the PEO and PEO/bacterial cellulose nanowhiskers (BCNW) (0.1 wt%) composite nanofibers. The functionalization of BCNW (f-BCNW) was performed by microwave plasma treatment for effects of nitrogen functionalization of chemically-driven BCNW. The N-containing functional groups of f-BCNW enhanced chemical bonding between the hydroxyl groups of the polymer chains in the PEO matrix and diameter size of PEO/f-BCNW (0.1 wt%) composite nanofibers were decreased more than PEO and PEO/BCNW (0.1 wt%) composite nanofibers on the same concentration. The strong interfacial interactions between the f-BCNW nanofillers and polymer matrix were improved the thermomechanical properties such as crystallization temperature, weight loss and glass transition temperature (Tg) compared to PEO and PEO/BCNW composites nanofibers. The results demonstrated that N2 plasma treatment of BCNW is very useful in improving thermal stability for bio-applications.

• Journal of the Korean Ceramic Society
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• v.56 no.6
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• pp.601-605
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• 2019

This work reports the preparation of ceramic hybrid films with illite-polyethylene composites analyzed as a function of concentration of added illite in polyethylene. The enhancement of oxygen and water-vapor transmission rate of illite-polyethylene film was evaluated to determine its influence on the freshness in fruit packaging. Particle size of illite materials was controlled in the range of 1~10 ㎛ and then mixed with LDPE to form the masterbatch. Ceramic hybrid films were prepared through a blown film making process. To determine the dispersity and abundancy of illite materials in the polyethylene matrix, various characterizations of illite-PE hybrid masterbatch and films were performed using SEM, TGA, and FT-IR. The oxygen and water-vapor transmission rate of illite-polyethylene film was found to be two times higher than that of LDPE film.

• Carbon letters
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• v.19
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• pp.32-39
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• 2016

In this work, we studied the effects of electrochemical oxidation treatments of carbon fibers (CFs) on interfacial adhesion between CF and epoxy resin with various current densities. The surface morphologies and properties of the CFs before and after electrochemical-oxidation-treatment were characterized using field emission scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and single-fiber contact angle. The mechanical interfacial shear strength of the CFs/epoxy matrix composites was investigated by using a micro-bond method. From the results, electrochemical oxidation treatment introduced oxygen functional groups and increased roughness on the fiber surface. The mechanical interfacial adhesion strength also showed higher values than that of an untreated CF-reinforced composite.

• Elastomers and Composites
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• v.22 no.4
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• pp.305-313
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• 1987

In this study, as one of the developing ways of the functional elastomer, improvement of the functionality of 1-Chlorobutadiene-Butadiene Copolymer(CB-BR) was attempt through curing reaction by moisture. The curing reaction of CB-BR was determined an use of $\gamma$-Aminopropyltriethoxysilane(APS) and $\gamma$-Aminopropylmethyldiethoxysilane(ADS) as a crosslinking agent with filler at so the uncrosslinked elastomer was exposured in the air and curing reaction by moisture in the air was studied. The results obtained are as follows. 1. APS was more efficient than ADS as a crosslinking agent for CB-BR 2. Optimum amount of APS for moisture cured elastomer was r=1.5(at the ratio of $[APS]/[Cl^*]$) also in case(r=1.5), elastomer formed after soaking $T_{72}$ had similar physical properties with elastomer crosslinked by sulfur and it was very good. 3. Uncrosslinked elastomer(CB-BR+APS+Silica) was easily crosslinked by exposure to the air, and the physical properties was also satisfactory.