• Polymer(Korea)
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• v.35 no.2
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• pp.124-129
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• 2011

Wood plastic composites (WPCs) are attracting a lot of interest recently. In this study, wood flour/polyethylene (PE) composites panels comprised of a coupling agent and nanoclay were prepared by melt-blending followed by compression molding. Five maleic anhydride grafted polyethylene (MAPE) coupling agents were tested, and the best choice and its optimum content were determined. The mechanical properties of the WPCs were measured by UTM, and the thermal properties were measured by TGA, DMA, DSC, and TMA. Adding just a small amount (1 phr) of organoclay made the tensile and flexural strength and the crystallinity of the WPC somewhat increase and the storage modulus and dimensional stability of the WPC largely increase. SEM images showed that the coupling agent drastically improved wood flour/PE interfacial bonding. Selecting the best coupling agent optimized content and adding a small amount of organoclay resulted in a high performance wood flour/PE composite.

• Korean Chemical Engineering Research
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• v.49 no.3
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• pp.285-291
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• 2011

NCO terminated polyurethane prepolymers were synthesized from isophorone diisocyanate(IPDI), poly (tetramethylene glycol)(PTMG) and dimethylol propionic acid(DMPA). Subsequently, waterborne polyurethanes were prepared by capping the NCO groups of polyurethane prepolymers with different types of silane coupling agents, such as methyltrimethoxysilane(MTMS), glycidoxypropyl trimethoxysilane(GPTMS), methacryloxypropyl trimethoxysilane (MPTMS) and aminopropyl triethoxysilane(APS). The average particle size of the waterborne polyurethane solutions was increased by adding silane coupling agents. Also, the coating films prepared from GPTMS, MPTMS and APS, exhibited better pencil hardness than those from pure waterborne polyurethane. On the other hand, the coating films from MTMS did not show an improved pencil hardness than those from pure waterborne polyurethane.

• Carbon letters
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• v.17 no.1
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• pp.79-84
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• 2016

• Elastomers and Composites
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• v.49 no.3
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• pp.239-244
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• 2014

Reaction between silica and silane coupling agent without solvent was investigated using transmission mode Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Bis[3-(triethoxysilylpropyl) tetrasulfide] (TESPT) was used as a silane coupling agent. After removing the unreacted TESPT, formation of chemical bonds was analyzed using FTIR and content of reacted TESPT was determined using TGA. Content of the coupling agent bonded to silica increased with increase in the coupling agent content, but the oligomers were formed by condensation reaction between coupling agents when the coupling agent was used to excess. In order to identify bonds formed among silica, coupling agent, and rubber, a silica-coupling agent-BR model composite was prepared by reaction of the modified silica with liquid BR of low molecular weight and chemical bond formation of silica-coupling agent-BR was investigated. Unreacted rubber was removed with solvent and analysis was performed using FTIR and TGA. BR was reacted with the coupling agent of the modified silica to form chemical bonds. Polarity of silica surface was strikingly reduced and particle size of silica was increased by chemical bond formation of silica-coupling agent-BR.

• YAKHAK HOEJI
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• v.48 no.3
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• pp.182-188
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• 2004

This study aimed to synthesize new anticonvulsive agents as potential dual acting prodrugs. For the synthesis of ester or amide prodrug types, p-hydroxybenzaldehyde or valproic acid was coupled with clinically usable anticonvulsants or GABAmimetics with use of DCC/DMAP coupling methods. Also their anticonvulsive activities were evaluated.

• Polymer(Korea)
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• v.38 no.6
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• pp.787-790
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• 2014

In this work, the epoxy specimens were prepared from diglycidyl ether of bisphenol F (DGEBF) with silane coupling agents (3-glycidoxypropyl trimethoxysilane (GPTMS)) in different ratios. Thermal stability was studied in terms of polymer decomposition temperature (PDT), temperature of maximum rate of weight loss ($T_{max}$), integral procedural decomposition temperature (IPDT), and decomposition activation energy ($E_a$) using TGA analysis. Adhesion properties of epoxy composite specimens were measured by UTM (universal testing machine) at atmosphere temperature. In this result, the adhesion properties of DGEBF were improved by addition of silane coupling agents compared to non-treated epoxy resin. However, when the content of GPTMS agent is more than 10 phr, adhesion properties decreased with increasing GPTMS agent.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.138.2-138.2
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• 2013

Copper oxide is a multi-functional material being used in various research areas including catalysis, electrochemical materials, oxidizing agents etc. Among these areas, we have synthesized and utilized graphene based copper oxide nanocomposites (CuOx/Graphene) for the catalytic applications (C-N cross coupling reaction). Briefly, Cu precursors were anchored on the graphite oxide(GO) sheets being exfoliated and oxidized from graphite powder. Two different crystalline structures of Cu2O and CuO on graphene and GO were prepared by annealing them in Ar and O2 environments, respectively. The morphological and electronic structures were systemically investigated using FT-IR, XRD, XPS, XAFS, and TEM. Here, we demonstrate that the catalytic performance was found to depend on oxidative states and morphological structures of CuOx graphene nanocomposites. The relationship between the structure of copper oxides and catalytic efficiency toward C-N cross coupling reaction will be discussed.

• YAKHAK HOEJI
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• v.51 no.2
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• pp.103-107
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• 2007

In these study novel 1,4-disubstituted carbocyclic nucleoside analogues were synthesized as potential antiviral agents. The coupling reaction of the alcohol 8${\alpha}$ with natural bases using Mitsunobu reaction afforded the target nucleosides 13, 14. The synthesized compounds were evaluated for their antiviral activity against various viruses such as HIV-1, HSV-1, HSV-2 and HCMV. Cytosine derivative 13 exhibited moderate antiviral activity against HIV-1 (EC$_{50}$=16.4 ${\mu}$M).

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.04a
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• pp.159-162
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• 2000

Interfacial and microfailure properties of carbon fiber/epoxy matrix composites were evaluated using both tensile fragmentation and compressive Broutman tests with acoustic emission (AE). Amino-silane and maleic anhydride polymeric coupling agents were used via the dipping and electrodeposition (ED), respectively. Both coupling agents exhibited higher improvements in interfacial shear strength (IFSS) under tensile tests than compressive cases. However, ED treatment showed higher IFSS improvement than dipping case under both tensile and compressive test. The typical microfailure modes including fiber break, matrix cracking, and interlayer failure were observed during tensile test, whereas the diagonal slippage in fiber ends was observed during compressive test. For both the untreated and treated cases AE distributions were separated well under tensile testing. On the other hand, AE distributions were rather closer under compressive tests because of the difference in failure energies between tensile and compressive loading. Under both loading conditions, fiber breaks occurred around just before and after yielding point. Maximum AE voltage fur the waveform of carbon or basalt fiber breakage under tensile tests exhibited much larger than those under compressive tests.

• Elastomers and Composites
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• v.53 no.2
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• pp.57-66
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• 2018

Styrene-butadiene rubber (SBR), reinforced with different contents of silica (with or without modification using silane coupling agents), was prepared by a modified sol-gel method involving hydrolyzation of tetraethoxysilane over an acid catalyst. The structures of the as-prepared samples were characterized using various techniques, such as scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. The mechanical properties of the as-prepared samples were discussed in detail. The results revealed an increasing of the storage modulus (G') with increase in the silica content without modification. In contrast, G' decreased after modification using silane coupling agents, indicating a reduction in the silica-silica interaction and improved dispersion of silica in the SBR matrix. Both tensile stress and hardness increased with increase in the silica content (with modification) in the SBR matrix, albeit with low values compared to the samples with un-modified silica, except for the case of silica modified using (3-glycidyloxypropyl) trimethoxysilane (GPTS). The latter observation can be attributed to the special structure of GPTS and the effort of oxygen atom lone-pair.