• Macromolecular Research
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• v.8 no.4
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• pp.153-164
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• 2000

By electrodeposition (ED) using a monomeric- and two polymeric coupling agents, the interfacial shear strength (IFSS) of carbon fiber/epoxy composites was investigated by fragmentation test. ED results were compared with the dipping and the untreated cases under dry and wet conditions. Multi-fiber composites (MFC) were used for the direct comparison for the untreated and the treated cases. Various treating conditions including time, concentration and temperature were evaluated, respectively. Under dry and wet conditions ED treatment exhibited much higher IFSS improvement compared to the dipping and the untreated cases. Monomeric- and polymeric coupling agents exhibited the comparative IFSS improvement. Adsorption mechanism between coupling agents and carbon fiber was analyzed in terms of the electrolyte molecular interactions during ED process based on to the chain mobility. The microfailure modes occurring from the fiber break, matrix and interlayer cracks were correlated to IFSS.

• Journal of the Semiconductor & Display Technology
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• v.12 no.3
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• pp.7-12
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• 2013

Ni-CNT(Carbon Nanotube) composite coatings is were formed by electrodeposition and their physical properties were investigated with variations of CNT content(1, 3, 6. 9 g/L) in the electrolyte solution, while the current density and electroplating time were fixed respectively at $6A/dm^2$ and 90 min.. With increasing CNT content from 1 to 9 g/L, incorporated CNTs into the composite coating were limited from 4.65 wt.% to 7.38 wt.%. Microhardness and contact angle values were increased with increasing CNT content of upto 3 g/L. With increasing the CNT content further, physical properties were degraded due to agglomeration, poor adhesion of CNTs to Ni matrix and thus rough surfaces. Optimum electroplating conditions were found to be the CNT content of 3 g/L, current density of 6 A/dm2 and electroplating time of 90 min.

• Journal of the Korean Ceramic Society
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• v.42 no.1
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• pp.50-55
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• 2005

New fast proton-conducting organic-inorganic nanocomposite membranes were successfully fabricated using polymer matrix obtained through proper oxidation of thiol ligands in (3-Mercaptopropyl) trimethoxysilane (MPTS) and hydrolysis/condensation reaction of (3-glycidoxypropyl) trimethoxysilane (GPTS). The obtained nanocomposite membranes showed relatively hirh proton-conductivity over $10^{-2}S/cm$ at $ 25^{circ}C$. The proton conductivities of the fabricated composite membranes increased up to $3.6{\times}10^{-1}$ S/cm cm by increasing temperature and relative humidity to $70^{circ}C$ and 100 $100RH\%$. The high proton conductivity of the composites Is due to the proton conducting path through the GPTS-derived 'pseudo-polyethylene oxide 'network in which sulfonic acid ligands work as a proton donor.

• Journal of Hydrogen and New Energy
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• v.20 no.2
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• pp.95-103
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• 2009

In order to improve the electrochemical, mechanical and electrocatalytic characteristics, engineering plastic of polyether ether ketone (PEEK) as polymer matrix was sulfonated (SPEEK) and the organic-inorganic blend composite membranes has been prepared by loading heteropoly acids (HPAs), including tungstophosphoric acid (TPA), molybdophosphoric acid (MoPA), and tungstosilicic acid (TSiA). And then these were covalently cross-linked (CL-SPEEK/HPA) as the electrolyte and MEA of polymer electrolyte membrane electrolysis (PEME). As a result, the optimum reaction conditions of CL-SPEEK/HPA was established and the electrochemical characteristics such as ion conductivity ($\sigma$) were in the order of magnitude: CL-SPEEK /TPA30 (${\sigma}=0.128\;S/cm^{-1}$) < /MoPA40 (${\sigma}=0.14\;S/cm^{-1})$ < /TSiA30 (${\sigma}=0.22\;S/cm^{-1}$) at $80^{\circ}C$, and mechanical characteristics such as tensile strength: CL-SPEEK /TSiA30 $\fallingdotseq$ /MoPA40 < /TPA30. Consequently, in regards of above characterisitics and oxidation durability, the CL-SPEEK/TPA30 exhibited a better performance in PEME than the others, but CL-SPEEK/MoPA40 showed the best electrocatalytic activity of cell voltage 1.71 V among the composite membranes. The dual effect of higher proton conductivity and electrocatalytic activity with the addition of HPAs, causes a synergy effect.

• Journal of the Korean Society for Heat Treatment
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• v.27 no.4
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• pp.169-174
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• 2014

The effect of varying amounts of graphite and $TiB_2$ on the electrical conductivity of composite bipolar plates was systematically studied. In this study, Titanium diboride ($TiB_2$) which has a high electrical conductivity, was selected as a filler and a additive material instead of conventional graphite. For proper distribution of the filler and matrix materials, ball milling using alumina balls was conducted for 1h, and then the hot press method was applied for the preparation of composite samples. The results showed a rapid increase in the electrical conductivity of composite bipolar plates at the critical filler content. However, $TiB_2$ and graphite composite bipolar plates showed similar increases in the electrical conductivity even though $TiB_2$ has a higher electrical conductivity than graphite. In addition, it was also found that a small addition of $TiB_2$ to graphite filler could be very effective for increasing the electrical conductivity and flexural strength of the composite bipolar plate.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.100-100
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• 2011

Nanomaterial architecture with highly ordered, vertically oriented $TiO_2$ nanotube arrays shows a good promise for diverse technological applications. As inspired from the literature reports that Nickel modification can improve the photocatalytic activity of $TiO_2$, it was planned to coat Ni into the $TiO_2$ matrix. In this study, first $TiO_2$ nanotubes(TiNTs) were prepared by anodization (60V,3min) in HF-free aqueous electrolyte on ultrasonically cleaned polished titanium sheet substrates ($1{\times}7cm^2$). The typical thickness of the sintered TiNT ($500^{\circ}C$for10min) was ~1 micronas confirmed from the FESEM study. In the next part, as-anodized and sintered TiNT/Ti photoanodes were used to coat Ni by AC electrodeposition from aqueous 0.1M nickel sulphate solution. During AC electrodeposition, conditions such as 1V DC offset voltage, 9V amplitude (peak-to-peak) and 750 Hz frequency were fixed constant and the deposition time was varied as 0.5 min, 1 min, 2 min and 10 min. The photoelectrochemical performance of pristine and Ni modified TiNT/Ti photoanodes was measured in 1N NaOH electrolyte under 1 SUN illumination in the potential range of -1V and 1.2V versus Ag/AgCl reference electrode. The photocurrent performance of TiNT/Ti photoanode decreased upon Ni modification and the results were confirmed after repeated experiments. This suggests us that Ni modification inhibits the photoelectrochemical performance of $TiO_2$ nanotubes.

• Polymer(Korea)
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• v.26 no.6
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• pp.785-791
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• 2002

The effect of the supercritical carbon dioxide (sc$CO_2$) on ion-conductive behaviors for polyether electrolytes based on, both poly (ethylene oxide) (PEO) and poly [oligo (oxyethylene glycol) methacrylate] (PMEO) with lithium triflate, LiCF$_3$SO$_3$, has been investigated. In particular, the present research is a new concept for improving the ionic conductivity of polyether electrolytes. The maximum ionic conductivity ($\sigma$$_{max}$) at room temperature of the PEO electrolyte was more than 100 times higher, and the $\sigma$$_{max}$ at 9$0^{\circ}C$ of the PMEO electrolyte was 30 times improved by the se$CO_2$ treatment, respectively. It was revealed that the penetration of $CO_2$ molecules into the polymer matrix causes the increase of carrier ions by ion-dispersion effect and the decrease of glass transition temperature (T$_{g}$) by plasticizing effect that results in the improvement of the ion transport behaviors.viors.

• Journal of the Korean Electrochemical Society
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• v.18 no.1
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• pp.1-6
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• 2015

In this study polystyrene derivative, VBCE, having a cyclic carbonate was synthesized by Williamson reaction and polymerized to poly(VBCE) successfully in an usual polymerization conditions. The obtained polymer was blended with PEGMA and the effect of composition on the ionic conductivity was investigated. Interestingly, the ionic conductivity was decreased from $4.2{\times}10^{-5}S\;cm^{-1}$ to $3.93{\times}10^{-6}S\;cm^{-1}$ with the poly(VBCE) contents of 5.8mol%. From the DSC study, it was found that the $T_g$ of the blend was increased from $-50^{\circ}C$ to $-21^{\circ}C$ by the addition of poly(VBCE). Therefore, it is believed that the presence of a polar cyclic carbonate makes polymer matrix harder and it is necessary to design new structures less hindered the mobility of the matrix.

• Journal of Hydrogen and New Energy
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• v.22 no.1
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• pp.42-50
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• 2011

The Montmorillonite (MMT) in the polymer matrix is expected to reduce methanol permeability due to the tortous path formed by dispersed silicate layers. However, the polymer composite membranes containing non-proton conducting inorganic particle tend to show low proton conductivity. To solve this problem, we used an ion exchange method to prepare functionalized MMT with various silane coupling agents. The modified MMT was randomly dispersed in sulfonated poly (arylene ether sulfone) (SPAES) matrix to prepare SPAES/modified MMT composite membranes. The performances of hybrid membranes for DMFCs application were investigated. The SPAES/modified composite membrane showed increased proton conductivity compared with the non-modified MMT composite membrane. However, the methanol permeability of the SPAES/modified membrane was higher than that of the non-modified MMT.

• Korean Journal of Materials Research
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• v.16 no.10
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• pp.606-613
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• 2006

This study was purposed to evaluate the influence of anodically oxidized film on titanium (Ti) onto MG-63 osteoblast-like cell attachment and activity. Only scratch lines created by polishing were seen in ASR and ANO-1 groups. About $1.5{\mu}m$-thick homogeneous oxide film which has pores of about $0.5{\mu}m$ diameter were formed in ANO-12. The crystalline structure of the oxide films formed by anodization in phosphoric acid electrolyte was $TiP_2O_7$. The total protein amounts of ANO-1 and ANO-12 groups showed higher values of maximum protein amount than that of AS-R group. At 3 days of incubation, total protein amount showed higher value in ANO-2 when comparing to that of AS-R (p<0.05). Based on the results of ALPase activity test, the degree of MG-63 cell differentiation for initial mineralization matrix formation was similar. For all the test groups after 1 day of incubation, MG-63 cells grew healthily in mono-layer with dendritic extensions. After incubation for 3 days, the specimen surfaces were covered more densely by cells, and numerous micro filaments were extruding to the extracellular matrix.