• Journal of Adhesion and Interface
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• v.7 no.4
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• pp.39-44
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• 2006

A new kind of silicone-epoxy composite is reported in this research. The silicone-epoxy resin was synthesized by the hydrosilylation of tetramethycyclotetrasiloxane and 4-vinyl-1-cyclohexene 1,2-epoxy with a high reaction yield. It was found that the obtained silicone-epoxy resin shows a high reactive activity to the aluminum complex-silanol catalyst. The resin could be cured under the catalysis of $(Al(acac)_3/Ph_2Si(OH)_2$ at a concentration below 0.1 wt% to give a hard cured resin showing excellent optical clarity, UV resistance and thermal stability. It was also found that the Si-H groups facilitated the curing reaction and the silicone-epoxy resin bearing Si-H group could be cured effectively even if $Ph_2Si(OH)_2h$ was absent. Moreover, the UV resistance and thermal stability were improved significantly by the introduction of Si-H groups. This is possibly due to the reductive property of Si-H groups which can annihilate radical and peroxide effectively. This kind of silicone-containing epoxy composite might have very promising applications as optical resin, optical adhesive and encapsulation materials for electronic devices.

• Journal of the Korean Ceramic Society
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• v.45 no.2
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• pp.119-125
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• 2008

The FAS(Fluoroalkylsilane)/Nafion inorganic-organic composite electrolyte membrane was successfully fabricated through sol-gel method. The FAS having hydrophobic functional group and silanol ligands is impregnated in $Nafion^{(R)}$ membrane to reduce methanol crossover. The prepared FAS/Nafion inorganic-organic composite electrolyte membrane consist of the hydrophobic FAS-derived silicate nano-particles and $Nafion^{(R)}$ matrix showed decrease of methanol crossover and reduction of humidity dependence without large sacrifice of proton conductivity. The microstructural analysis of the composite membranes was performed using FESEM and FTIR. And the effect of the incorporation of the hydrophobic FAS-derived silicate nano-particles into $Nafion^{(R)}$ membrane was investigated via solvent uptake, membrane expansion rate, humidity dependency of proton conductivity and contact angle measurement.

• Polymer(Korea)
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• v.28 no.2
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• pp.170-176
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• 2004

The effect of reaction conditions on the size and size distribution of superparamagnetic iron oxide coated with siloxane was big investigated by using dynamic light scattering. The hydrogen bond between the hydroxyl groups on tile surface of the magnetite and silanol was confirmed by FT-IR. The size of nanoparticles increased with the reaction temperature, but decreased with monomer contents and agitation speeds. There was not a big difference in size of nanoparticles, prepared by different reaction conditions, but its distribution was in the range of 14∼41nm. All samples exhibited the superparamagnetic nature. The magnetic susceptibility of the nanoparticles increased with the reaction temperature while it decreased with the monomer content and agitation speed.

• Elastomers and Composites
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• v.55 no.3
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• pp.215-221
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• 2020

Silica/SBR (styrene-butadiene rubber) compounds are the primary constituents of tire treads. Furthermore, the excellent dynamic viscoelastic properties of silica lead to good fuel efficiencies. However, the silanol group on the surface of silica does not mix well with non-polar rubber because of its polarity. This incompatibility causes aggregation due to the occurrence of hydrogen bonding between the hydroxyl groups, thereby reducing the dispersibility of silica. Recently, the wet master batch (WMB) process has been applied to overcome these disadvantages, and research on silica dispersants that can be used in the WMB process has been increasing. In this study, we prepared silica/SBR compounds by using three types of eco-friendly cellulose-based dispersants in the WMB process, namely: cellulose-, sodium carboxymethyl cellulose, and nanocellulose-based dispersants. Subsequently, we compared the vulcanization characteristics, viscoelastic properties, and mechanical properties of the compounds. The silica dispersibility in the rubber compounds was improved with the addition of the nano-cellulose dispersant, resulting in the enhancement of the workability, hardness, tensile strength, and wear resistance of the SBR compound.

• Journal of Adhesion and Interface
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• v.7 no.4
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• pp.32-38
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• 2006

A series of organic-inorganic hybrids, PCL/EP/$SiO_2$, involving epoxy resin and triethoxysilane-terminated polycaprolactone elastomer (PCL-TESi) were prepared via polymerization of diglycidyl ether of bisphenol A (DGEBA) with amine curing agent KB-2 and sol-gel process of PCL-TESi. The curing reactions were started from the initially homogeneous mixture of DGEBA, KB-2 and the PCL-TESi. The organicinorganic hybrids containing up to 4.95% (wt) of $SiO_2$ were obtained and characterized by FT-IR, transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). It was experimentally shown that the swelling property in toluene, morphologies and thermal properties of the resulting hybrids were quite dependent on the contents of $SiO_2$. The crosslink network density decreases with increasing of the PCL-TESi. And in TEM, the phase separated morphology of these hybrids was found, which resulted from the coagulation of Si-O-Si networks resulting from $-Si(OC_2H_5)_3$ of PCL-TESi self-curing by hydrolytic silanol condensation, with the advancement of the curing reaction in the modified epoxy resin systems. Meanwhile, the change of the $SiO_2$ content made the morphologies changed from aggregated particles of Si-O-Si in the hybrid to nanocluster of interconnected Si-O-Si particles, then to aggregated Si-O-Si dispersing in the continuous cured epoxy phase again, and last to co-continuous interpenetrating network. The glass transition behavior of the hybrid material was cooperative motion of large chain segments, which were hindered by the inorganic Si-O-Si network. And in TG analysis, the characteristic temperature at 5% of weight loss was evidently increased from $120.5^{\circ}C$ of pure cured epoxy to $277.6^{\circ}C$ of 3.84% (wt) of $SiO_2$ modified epoxy due to the existence of Si-O-Si when PCL-TESi was added in the hybrid.

• Bulletin of the Korean Chemical Society
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• v.25 no.5
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• pp.681-686
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• 2004

Ti-ZSM-5 prepared by secondary synthesis, from the reaction of H-ZSM-5 with vapor phase $TiCl_4$, was characterized with several physicochemical techniques including FT-IR and UV/VIS-DRS. It was found that zeolite structure, surface area and pore volume did not change, and the framework aluminum could not be replaced by titanium atom during the secondary synthesis of Ti-ZSM-5. The incorporation of titanium into the framework might be due to reaction of $TiCl_4$with the silanol groups associated with defects or surface sites. The formation of extra-framework titanium could not be avoided, unless the samples were further treated by water vapor at 550 $^{\circ}C$ or higher temperature. High temperature steam treatment of Ti-ZSM-5 prepared by chemical vapor deposition with $TiCl_4$was efficient to prevent the formation of non-framework titanium species. Ti-ZSM-5 zeolites prepared in this work contained only framework titanium species and exhibited improved catalytic property close to TS-1 prepared by hydrothermal synthesis.

• Korean Journal of Materials Research
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• v.22 no.8
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• pp.433-438
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• 2012

A chemical process involves polymerization within microspheres, whereas a physical process involves the dispersion of polymer in a nonsolvent. Nano-sized monodisperse microspheres are usually prepared by chemical processes such as water-based emulsions, seed suspension polymerization, nonaqueous dispersion polymerization, and precipitation polymerizations. Polymerization was performed in a four-necked, separate-type flask equipped with a stirrer, a condenser, a nitrogen inlet, and a rubber stopper for adding the initiator with a syringe. Nitrogen was bubbled through the mixture of reagents for 1 hr. before elevating the temperature. Functional silane (3-mercaptopropyl)trimethoxysilane (MPTMS) was used for the modification of silica nanoparticles and the self-assembled monolayers obtained were characterized by X-ray photoelectron spectroscopy (XPS), laser scattering system (LSS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), elemental analysis (EA), and thermogravimetric analysis (TGA). In addition, polymer microspheres were polymerized by radical polymerization of ${\gamma}$-mercaptopropyl modified silica nanoparticles (MPSN) and acrylamide monomer via precipitation polymerization; then, their characteristics were investigated. From the elemental analysis results, it can be concluded that the conversion rate of acrylamide monomer was 93% and that polyacrylamide grafted to MPSN nanospheres via the radical precipitation polymerization with AAm in ethanol solvent. The microspheres were successfully polymerized by the 'graft from' method.

• Polymer(Korea)
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• v.25 no.4
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• pp.512-520
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• 2001

One of the most important factors which affect the mechanical properties of fiber-reinforced composite materials is the interfacial shear strength (IFSS). The IFSS of glass fiber and polycarbonate (PC)/styrene-co-acrylonitrile (SAN) blend system has been measured by the single fiber fragmentation test (SFFT). SAN contents were varied up to 30 wt% and the IFSS increased with the SAN contents. Styrene-co-maleic anhydride (SMA) was used as the compatibilizer and the glass fiber was surface treated with organosilane coupling agents. Addition of small amount of SMA in PC/SAN blend improved the IFSS by chemical bonding between maleic anhydride and silanol. The optimum MA content was 0.4 wt% of total matrix contents. Also, IFSS was greatly affected by the miscibility condition of SAN/SMA blends, which depended on the copolymer composition of SAN and SMA. It was found out that, higher IFSS could be obtained when the SAN/SMA blend was in miscible pairs. In case of SAN/SMA miscible pairs, the IFSS depended on the MA content in total matrix, not on the MA content in SMA.

• Elastomers and Composites
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• v.50 no.2
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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.

• Journal of the Mineralogical Society of Korea
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• v.13 no.4
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• pp.186-195
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• 2000

To study phosphate adsorption on kaolinite, $^{31}$ P MAS NMR(magic angle spinning nuclear magnetic resonance spectroscopy)has been used for kaolinite reacted in 0.1 M phosphate solutions at pH’s from 3 to 11. There are at least 3 different forms of phosphate on kaolinite. One is the phosphate physically adsorbed on kaolinite surface (outer-sphere complexes) or species left after vacuum-filtering. The second is the phosphate adsorbed by ligand exchange (inner-sphere complexes), and the third is Al-phosphate precipitates which are pH dependent. Most of the inner-spherer complexes and surface precipitates are mainly on hydroxided Al(aluminol) rather than hydroxided Si(silanol). These are pertinent with the results obtained from the phosphate adsorption experiments on silica gel and ${\gamma}$-Al$_2$O$_3$ as model compounds, respectively. The two peaks with more negative chemical shifts(more shielded) than the ortho-phosphate peak (positive chemical shift) are assigned to be the inner-sphere complexes and surface precipitates. The $^{31}$ P chemical shifts of the Al-phosphate precipitates are more negative than those of inner-sphere complexes at a given pH due to the larger number of P-O-Al linkages per tetrahedron. The chemical shifts of both the inner-sphere complexes and surface precipitates are more negative than those of inner-sphere complexes at a given pH due to the larger number of P-O-Al linkages per tetrahedron. The chemical shifts of both the inner-sphere complexes and surface precipitates become progressively less shielded with increasing pH. For the inner-sphere complexes, decreasing phosphate protonation combined with peak averaging by rapid proton exchange among phosphate tetrahedra with different numbers of protons is though to be the reason for the peak change. The decreasing shielding with increasing pH for surface precipitates is probably due to the decreasing average number of P-O-Al linkages per tetrahedron combined with decreasing protonation like inner-sphere complexes.