• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.5
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• pp.20-26
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• 2008

Behavior of micro stickies was analyzed using model micro stickies prepared with PVAc emulsion adhesive. Flocculation of micro stickies increased with temperature. Acidic state also induced greater flocculation of micro stickies since they became more unstable under these conditions. Flocculation of micro stickies increased as calcium ion concentration increased. But the presence of calcium carbonates made micro stickies dispersed indicating that calcium carbonates cause two different effects on the behavior of micro stickies. Talc increased flocculation of micro stickies because of its hydrophobic nature. Cationic polymer increased flocculation of micro stickies. Especially cationic starch has far greater effect in flocculating sticky particles by forming bridging flocculations.

• Restorative Dentistry and Endodontics
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• v.36 no.2
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• pp.139-148
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• 2011

Objectives: This study investigated the effect of the strength and wetting characteristics of adhesives on the bond strength to dentin. The experimental adhesives containing various ratios of hydrophobic, low-viscosity Bis-M-GMA, with Bis-GMA and TEGDMA, were made and evaluated on the mechanical properties and bond strength to dentin. Materials and Methods: Five experimental adhesives formulated with various Bis-GMA/Bis-MGMA/TEGDMA ratios were evaluated on their viscosity, degree of conversion (DC), flexural strength (FS), and microtensile bond strength (MTBS). The bonded interfaces were evaluated with SEM and the solubility parameter was calculated to understand the wetting characteristics of the adhesives. Results: Although there were no significant differences in the DC between the experimental adhesives at 48 hr after curing (p > 0.05), the experimental adhesives that did not contain Bis-GMA exhibited a lower FS than did those containing Bis-GMA (p < 0.05). The experimental adhesives that had very little to no TEGDMA showed significantly lower MTBS than did those containing a higher content of TEGDMA (p < 0.05). The formers exhibited gaps at the interface between the adhesive layer and the hybrid layer. The solubility parameter of TEGDMA approximated those of the components of the primed dentin, rather than Bis-GMA and Bis-M-GMA. Conclusions: To achieve a good dentin bond, a strong base monomer, such as Bis-GMA, cannot be completely replaced by Bis-M-GMA for maintaining mechanical strength. For compatible copolymerization between the adhesive and the primed dentin as well as dense cross-linking of the adhesive layer, at least 30% fraction of TEGDMA is also needed.

• Applied Chemistry for Engineering
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• v.31 no.2
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• pp.230-236
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• 2020

In this study, an adhesive tape with water and impact resistance for mobile devices was developed using a UV-curable urethane acrylate based polymer as a substrate. The substrate fabricated by UV-curable materials shows hydrophobicity and poor wettability, which significantly deteriorates the interface-adhesions between the substrate and acrylic adhesive. In order to improve the interface adhesion, 3-glycidoxy-propyl trimethoxysilane (GPTMS), a silane coupling agent having epoxy functional groups, was selected and incorporated into UV-curable urethane acrylate based polymer resins in various contents. The changes of the chemical composition according to the contents of GPTMS was studied with Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) to know the surface bonding properties. Also mechanical properties of the substrate were characterized by tensile strength, gel fraction and water contact angle measurements. The peel strengths at 180° and 90° were measured to compare the adhesion between the substrate and adhesive according to the silane coupling agent contents. The mechanical strength of the urethane acrylate adhesive tape decreased as the silane coupling agent increased, but the adhesion between the substrate and adhesives increased remarkably at an appropriate content of 0.5~1 wt%.

• Restorative Dentistry and Endodontics
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• v.36 no.4
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• pp.280-289
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• 2011

Objectives: The purpose of this study was to evaluate ${\mu}TBS$ (microtensile bond strength) of current dentin bonding adhesives which have different hydrophobicity with low-shrinkage silorane resin. Materials and Methods: Thirty-six human third molars were used. Middle dentin was exposed. The teeth were randomly assigned to nine experimental groups: Silorane self-etch adhesives (SS), SS + phosphoric acid etching (SS + pa), Adper easy bond (AE), AE + Silorane system bonding (AE + SSb), Clearfil SE bond (CSE), CSE + SSb, All-Bond 2 (AB2), AB2 + SSb, All-Bond 3 (AB3). After adhesive's were applied, the clinical crowns were restored with Filtek LS (3M ESPE). The 0.8 mm ${\times}$ 0.8 mm sticks were submitted to a tensile load using a Micro Tensile Tester (Bisco Inc.). Water sorption was measured to estimate hydrophobicity adhesives. Results: ${\mu}TBS$ of silorane resin to 5 adhesives: SS, 23.2 MPa; CSE, 19.4 MPa; AB3, 30.3 MPa; AB2 and AE, no bond. Additional layering of SSb: CSE + SSb, 26.2 MPa; AB2 + SSb, 33.9 MPa; AE + SSb, no bond. High value of ${\mu}TBS$ was related to cohesive failure. SS showed the lowest water sorption. AE showed the highest solubility. Conclusions: The hydrophobicity of adhesive increased, and silorane resin bond-strength was also increased. Additional hydrophobic adhesive layer did not increase the bond-strength to silorane resin except AB2 + SSb. All-Bond 3 showed similar ${\mu}TBS$ & water sorption with SS. By these facts, we could reach a conclusion that All-Bond 3 is a competitive adhesive which can replace the Silorane adhesive system.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.4
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• pp.175-183
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• 2002

In this paper, the surface modification effect of self-assembled monolayer(SAM) of 1-dodecanethiol [$CH_3$($CH_2$)$_{11}$SH] used as an anti-adhesive film in micromolding process was studied. Monolayers of 1-dodecanethiol[$CH_3$(CH$_2$)$_{11}$SH] were obtained by immersing a metal place in pure 1-dodecanethiol. SAM film on the nickel plate has been examined by using X-ray photoelectron spectroscopy(XPS). The focus has been placed on S-Ni bonding. From the XPS analysis, sulfur atoms were detected from the SAM film as a chemical composition of S-Ni. In order to measure an adhesion force of the SAM-coated nickel surface, atomic force microscopy(AFM) was used in force-distance mode, which whows the micro-adhesive force on solid surface. It was shown that adhesion forces measured from the SAM-coated nickel surface and the Ni surface without SAM coating were 3.52nN and 5.32nN, respectively. In order to investigate the effect of SAM coating on the surface foughness the replica in demolding process, hot embossing experiments were performed using a SAM-coated nickel master and a nickel master without SAM coating. Surface roughness of replica from the SAM-coated master showed 25nm and that of replica from master without SAM coating was 35nm. The smoother surface roughness of the replica from the SAM-coated, master is believed to result from reduction in the adhesion forces.ces.

• Journal of Adhesion and Interface
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• v.19 no.4
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• pp.145-153
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• 2018

In this study, adhesion promoters with acrylate and carboxylic acid moiety were synthesized from malenized polybutadiene and 2-hydroxyethyl acrylate for producing adhesive film with low water absorption and high adhesion. The surface properties, adhesion strength, mechanical properties and water absorption of adhesive films were characterized according to the amount of acrylate and carboxylic acid in the synthesized adhesion promoters. As the carboxylic acid in the adhesion promoters increased, the adhesion strength showed a tendency to increase and the mechanical properties also improved compared to the commercial adhesion promoter. The compatibility of adhesion promoters improved remarkably due to the presence of polybutadiene (hydrophobic nature), maleic anhydride (hydrophilic nature) and carboxylic acid (hydrophilic nature).

• Animal cells and systems
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• v.13 no.2
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• pp.161-167
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• 2009

The cuticle of spider's exoskeleton is a hydrophobic and non-adhesive material, but the jumping spiders have the distinctive attachment apparatus for adhesion on smooth dry surface without sticky fluids. We have examined the whole tarsal appendages of the jumping spider, Plexippus setipes with using scanning electron microscope to reveal the fine structural characteristics of the dry adhesion system. All eight legs have the scopulae with a pair of claws on the tip of feet. Each scopula is composed of two groups of setae that are capable of dry adhesion on smooth surface, and the hook structure of the claw is advanced to move on the rough surface. The setae toward the bottom of the tarsal segment are densely covered by numerous setules on the underside which broadened from middle to distal portion. It has been revealed by this research that the contact area of the setule is always a triangular shape, and these cuticular surfaces are connected by the elongated stalks from the underlying setae. It is likely that the nano-scale structures including a triangular depression and a longitudinal groove on each setule could functionate when the spider detach its feet from the substrate.

• Journal of the Semiconductor & Display Technology
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• v.16 no.1
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• pp.106-111
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• 2017

When a substrate with a pixel-defining layer (bank) is coated, there arises capillary force due to surface tension and adhesive forces between a solvent and the bank layer. It brings in a degradation of film thickness and emission uniformities within pixels. With an attempt to suppress it, we have performed fluid flow simulations of capillary arise by varying the contact angle of bank and the bank structure. We have first demonstrated that the fluid flow model can reproduce the capillary phenomenon that was observed experimentally. It has been found that capillary arise can be suppressed using a hydrophobic material for the bank layer. Furthermore, it was suppressed by tilting the sidewalls outwardly (i.e., using a positive photoresistor). We can obtain very uniform films when the slope is $50^{\circ}$ with the contact angle of $40^{\circ}$.

• Journal of Adhesion and Interface
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• v.18 no.1
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• pp.25-32
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• 2017

For application to display module junction process, the silk screen printing based on UV curable acrylic pressure sensitive adhesive(PSA) with silica nano-particles and the rheological properties were studied to investigate the effect on printability and adhesion. The monomers for PSA were based on 2-ethylhexyl acrylate(2-EHA) and acrylic acid(AA) 93:7, butyl acylate(BA), 2-hydroxyethyl acrylate(2-HEA) and tetrahydrofurfuryl acrylate(THFA) were added. Additionally, hydrophobic and hydrophilic nano-particles AEROSIL R974 and AEROSIL 200 were added, respectively. When the ratio of nano-particle was used above 4 or 7 phr, G' and ${\eta}^*$ were increased significantly. When the ratio of AEROSIL 200 was used above 7 phr, the penetration property was decreased during the silk screen printing. We found that the adhesion was decreased with increasing the nano-particle content, and it was decreased in the case of the hydrophilic nano-particle AEROSIL 200.

• Membrane Journal
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• v.24 no.4
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• pp.301-310
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• 2014

In this study, the silica nanoparticles were considerably chosen to improve a dimensional stability, proton transport and electrochemical performance of the resulting inorganic-organic nanocomposite membranes. For this purpose, hydrophobic silica (Aerosil$^{(R)}$ 812, Degussa) and hydrophilic silica (Aerosil$^{(R)}$ 380, Degussa) nanoparticles were, respectively, introduced into a Sulfonated poly(arylene ether sulfone) (SPAES) polymer matrix. The $SiO_2$ particles are evenly dispersed in a SPAES matrix by the aid of a non-ionic surfactant (Pluronics$^{(R)}$ L64). A $SiO_2$ content plays an important role in membrane microstructures and membrane properties such as proton conductivity and water uptake. Therefore, to study nanocomposite membranes with excessive amount of silica, the content of silica nanoparticles were increased up to 5 wt%. Interestingly, a hydrophobic $SiO_2$ containing nanocomposite membrane showed better electrochemical performance (29% higher than pristine SPAES) despite of low proton conductivity due to its adhesive properties with a catalyst layer in a single cell test. All the silica-SPAES membranes exhibited better performance than a pristine SPAES membrane.