• Polymer(Korea)
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• v.39 no.2
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• pp.300-310
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• 2015

In this study, we modified silica nanoparticles with N-[3-(trimethoxysilyl)propyl]ethylenediamine (TPED) silane coupling agent, which has one primary and one secondary amino groups in a molecule, to introduce amino groups on the silica surface. After modification of silica, we used 3-(acryloyloxy)-2-hydroxypropyl methacrylate (AHM) to introduce methacrylate groups by Michael addition reaction. We found about 30% of N-H groups on the TPED modified silica surface reacted with acrylate groups of AHM compared to about 85% of reaction between N-H groups of pure TPED with acrylate groups of pure AHM. This lower degree of Michael addition reaction for heterogeneous reaction between N-H groups on the solid TPED modified silica and liquid AHM compared to homogeneous reaction between pure liquid TPED and pure liquid AHM may be caused by lower mobility of grafted amino groups of TPED moiety and higher steric hindrance caused by solid silica particles.

• Polymer(Korea)
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• v.37 no.6
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• pp.777-783
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• 2013

We used dipodal type bis[3-(trimethoxysilyl)propyl]amine (BTMA) silane coupling agent to modify silica nanoparticles to introduce secondary amino groups on the silica surface. These grafted N-H groups were reacted with glycidyl methacrylate (GMA) to introduce polymerizable methacrylate groups on the silica surface. After modification reaction, we used several analytical techniques such as Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA) and solid state $^{13}C$ cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance spectroscopy (NMR) to analyze the effects of reaction time, reaction temperature and used GMA concentration on the modification degree between N-H groups on the silica surface and epoxide groups of GMA. We found increased introduction of methacrylate groups on the silica surface by ring opening reaction of epoxide groups of GMA with N-H groups on BTMA treated silica with increased reaction time, reaction temperature and used GMA concentration within our experimental conditions.

• Rubber Technology
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• v.9 no.1
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• pp.1-12
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• 2008

Effects of silane modifier, bis(triethoxysilylpropyl) tetrasulfide (TESPT(S4)) and bis(triethoxysilylpropyl) disulfide (TESPD(S2)), on silica filled compound were investigated upon processability, dynamic, mechanical, heat build-up, blowout properties, and silica dispersion in natural rubber (NR). The temperature of the S2 treated silica compound generated higher than that of the S4 treated compound during internal mixer compounding. The shear viscosity of the S2 compound exhibited lower than that of the S4 compound and the viscosity measured in dynamic mode was close to each other. The elongation modulus of the S2 compound exhibited lower than that of the S4; however, the tear resistance strength of the S2 compound exhibited higher than that of the S4 compound. The loss tan$\delta$ values of the S2 compound exhibited higher than those of the S4 at room temperature. The augmentation of the test temperature lowered the tan$\delta$ values of each compound, which results in close tan$\delta$ values to each other at $100^{\circ}C$. The S2 compound deformed less than the S4 compound, and the blowout time of each compound was close to each other. The S2 compound generated more heat build-up than the S4 compound. The abrasion loss of the S2 compound was less than that of the S4 compound. The size of the silica agglomerate reduced on both S4 and S2 compounds upon vulcanization. The addition of the bifunctional silanes (S2 and S4) on silica filled NR compound improved the processability of each compound and their effects were more significant on the S2 compound than the S4 compound. After vulcanization the silica agglomerate size of each compound reduced compared with before vulcanization.

• Journal of Adhesion and Interface
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• v.10 no.3
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• pp.117-126
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• 2009

Epoxy/anhydride systems with silica filler were studied to improve the cure behavior and characteristics. To study the curing process of epoxy/anhydride using DSC and a stress rheometer, it was observed that gelation temperature increased by increasing the thermal rate or in high isothermal conditions, while it was observed that the degree of cure at gelation decreased. Thermal stability of the epoxy/anhydride system showed any increment by increasing silica contents, except slight decrease of weight by containing humidity. The epoxy resin cured with 30% of silica filler decreased coefficient thermal expansion (CTE) about 33% to show $40ppm/^{\circ}C$. Specimens filled with 30 wt% of silica showed 60% increase in storage modulus at $30^{\circ}C$ to show 3909 MPa compared with neat resin to 2,377 MPa. Epoxy/anhydride systems with surface treated silica by silane coupling agent decreased storage modulus.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.4
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• pp.409-414
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• 2019

Silica and polymethylsilsesquioxane (PMSQ) are silicone powders widely used as cosmetics. We synthesized silica-PMSQ composites via sol-gel method using tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMS) as precursors of silica and PMSQ, respectively. Shape of the composites was controlled by varying the ratios of TEOS and MTMS, which were used as silane monomers. Silica-PMSQ composites showed three different shapes, which were sphere-shape, raspberry- shape, and donut- shape. All of them had soft touch, easy water dispersion, and soft focus effect in common. However, each shape showed some differences in sense of use, adhesion, and strength of the soft focus effect. Raspberry-shape composite had the strongest soft focus effect, donut-shape one had the strongest adhesion, and sphere-shape one had the best in softness. Thus, it is concluded that by varying the ratios of TEOS and MTMS silica-PMSQ composites could be easily synthesized into different shapes, providing various functions. This method can be applied to manufacture functional cosmetics.

• Elastomers and Composites
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• v.52 no.4
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• pp.280-286
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• 2017

The mechanical and dynamic properties according to the content of filler, plasticizer, and crosslinking agent of rubber composites for Lipseal were measured in this study. The mechanical properties of the composite including the silane coupling agent and silica were found to be superior to those of the composite containing carbon black. It was found that the rebound resilience characteristics were influenced by the crosslink density of sulfur rather than the filler or plasticizer. In the case of recovery, it was confirmed that the elastic restoring force improved in the compression deformation condition and recovery increased as the crosslinking density increased. The rubber composite for Lipseal of this study is expected to improve the manufacturing technology of the rubber composite which can implement the optimum function for recognizing the performance such as oil resistance, durability and compression set.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.23 no.2
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• pp.58-69
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• 2014

In case of esthetic restorative procedure with zirconia restoration, we have to use resin cement because of not only just for retention but also esthetic reason. In such a clinical situation, we have to consider two bonding interfaces, one is tooth surface to resin cement and the other is zirconia surface to resin cement. There is well established bonding protocol between tooth surface to resin cement, but bonding protocol of zirconia surface to resin cement is still controversial. In scientific point of view, there are two mechanism for bonding of zirconia restoration.. One is mechanical retention and the other is chemical adhesion. However, we have three different options for bonding of zirconia restoration in clinical situation; 1) Tribo-chemical coating with silica and silane coupling agent 2) Zirconia primer with phosphate chemistry 3) Self-adhesive resin cement with phosphate chemistry.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1927-1929
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• 2005

Colloidal Silica(CS)/methyltrimethoxy silane(MTMS) sol solutions were prepared in variation with synthesizing parameters such as kinds of CS, acidity and reaction time. In order to understand its surface properties, sol-gel coating films on glass were fabricated. The coating film obtained from CS/MTMS sol had stable contact angle and more enhanced flat surface at reaction time of 24 hours. In case of the initial and final period of reaction, the coating films had unstable contact angle and more rough surface. In addition, surface of CS/MTMS sol-gel coating film was more rougher with increasing of acidity.

• Transactions on Electrical and Electronic Materials
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• v.18 no.4
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• pp.203-206
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• 2017

The effect of the content of microsilica and nanosilica continuously modified with hydroxy silane and epoxy-modified silicone in cycloaliphatic epoxy/microsilica/nanosilica composites (EMNCs) on the mechanical and water repellent properties was evaluated. Surface-modified micro- and nanosilica was well-mixed with a cycloaliphatic epoxy resin in the presence of polyester-modified polydimethylsiloxane (PEM-PDMS) as a dispersing agent using an ultrasonicator. Tensile and flexural tests were carried out using a universal testing machine (UTM). The water repellent property was evaluated by contact angle measurements of water on the composite surface. Tensile strength of the composite could be enhanced by 32.2% up to 91.4 MPa, and the flexural strength was raised to 122.0 MPa, which is 38.8% higher than that of neat epoxy. The contact angle of water on the composite was as high as $104.1^{\circ}$.

• Tribology and Lubricants
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• v.22 no.4
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• pp.182-189
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• 2006

In this paper, the adhesion characteristics between a fused silica without or with an anti-sticking layer and a thermoplastic polymer film used in thermal NIL were investigated experimentally in order to identify the release performance of the anti-sticking layer. The anti-sticking layers were derived from fluoroalkylsilanes, (1H, 1 H, 2H, 2H-perfluorooctyl)trichlorosilane ($F_{13}-OTS$) and (3, 3, 3-trifluoropropyl)trichlorosilane (FPTS), and coated on the silica surface in vapor phase. The commercial polymers, mr-I 7020 and 8020 (micro resist technology, GmbH), for thermal NIL were spin-coated on Si substrate with a rectangular island which was fabricated by conventional microfabrication process to achieve small contact area and easy alignment of flat contact sur- faces. Experimental conditions were similar to the process conditions of thermal NIL. When the polymer film on the island was separated from the silica surface after imprint process, the adhesion force between the silica surface and the polymer film was measured and the surfaces of the silica and the polymer film after the separation were observed. As a result, the anti-sticking layers remarkably reduced the adhesion force and the surface damage of polymer film and the chain length of silane affects the adhesion characteristics. The anti-sticking layers derived from FPTS and $F_{13}-OTS$ reduced the adhesion force per unit area to 38% and 16% of the silica sur-faces without an anti-sticking layer, respectively. The anti-sticking layer derived from $F_{13}-OTS$ was more effective to reduce the adhesion, while both of the anti-sticking layers prevented the surface damages of the polymer film. Finally, it is also found that the adhesion characteristics of mr-I 7020 and mr-I 8020 polymer films were similar with each other.