• Journal of Adhesion and Interface
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• v.15 no.2
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• pp.69-76
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• 2014

Two kinds of epoxy-functionalized alkoxysilane (EAS) compounds (EAS-MS and EAS-ES) were successfully synthesized through the reaction between epoxy resin (YD-128) and aminopropyl trimethoxysilane (APTMS) or aminopropyl triethoxysilane (APTES). By the hydrolysis-polycondensation reaction of EAS compounds with 3-Glycidyloxypropyl trimethoxysilane (GPTMS) and Tetraethyl orthosilicate (TEOS), silica/epoxy nanohybrids could be prepared at various compositions of EAS to GPTMS/TEOS. Prepared nanohybrids were yellow transparent and miscible with various organic solvents. By the reaction silica/epoxy nanohybrids with curing agents (TETA or acrylic acid), cured hybrids films could be obtained. These cured films showed higher thermal stability and mechanical property compared to cured neat epoxy resin. TEM and AFM images showed formation of nano-sized silica nanoparticles within cured hybrid films.

• The Journal of the Convergence on Culture Technology
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• v.8 no.2
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• pp.349-354
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• 2022

This research was conducted in order to improve the hydrolysis resistance and mechanical properties of a resin compound and biodegradable mulching film, produced through the use of PBAT(Poly Butylene Adipate-co-Terephthalate) and PLA(Poly Lactic Acid). Various ratios of chain extenders and mechanical properties according to the annealing temperature conditions were investigated. The annealing process showed that compound resin can improve the crystallization capacity. In addition, incorporation of the chain extender was shown to improve and increase the tensile strength and hydrolysis resistance of the film. In the case of 0.6phr chain extender, the tensile strength was 383.0Kgf/cm², which was improved by 155% compared to the control films. When the blow up ratio(BUR) was 2.5, the optimal tensile strength of the film increased greatly, expanding up to 379.0/195.2kgf/cm² in the both machine direction (MD) and transverse direction (TD).

• Journal of the Korean Wood Science and Technology
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• v.14 no.2
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• pp.29-35
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• 1986

This study was carried out to examine the effect of aluminium sulfate addition to the alkali-acid catalyst phenolic resin for the manufacture of the kapur (Dryobalanops spp.) plywood on the reduction of phenolic resin spreading. On the manufacture of plywood, Adhesive Contents such as 50g/$m^2$, 75g/$m^2$ and 150g/$m^2$ were treated. The spreading adhesive content of 50g/$m^2$ and 75g/$m^2$ had been controlled to about 150g/$m^2$ added with the water in order to get sufficient spreading and controlled to pH 4.5 with aluminium sulfate [$Al_2(SO_4)_3$]. The results are summarized as follows: 1. Specific gravities of air dried plywood manufactured from each adhesive ranged from 0.77 to 0.86 and their moisture contents met the KS requirements. 2. In dry and wet shear strengths, 150 $P_{Al{\cdot}Ac}$ adhesive showed the highest and 75 $P_{Al{\cdot}Ac{\cdot}Am}$ adhesive indicated higher value than 150 $P_{Al{\cdot}Ac}$ adhesive. 3. In case of glue shear strength after boiling test, 150 $P_{Al{\cdot}Ac}$ adhesive was the best and adding of aluminium sulfate was not effective on reinforcement of boiling water resistance of phenolic resin, but met KS requirements. 4. 75 $P_{Al{\cdot}Ac{\cdot}Am}$ adhesive showed the good shear strength and met KS requirements. Therefore, adding of aluminium sulfate was very efficient for economical plywood manufacture.

• Applied Chemistry for Engineering
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• v.3 no.2
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• pp.318-326
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• 1992

Vinylester resin was synthesized by reacting epoxy resin with MAA(methacrylic acid) at a equivalent ratio of 1.1/1.0 in the presence of N,N dimethyl benzylamine. Low molecular weight epoxy(DER 331) was used together with higher molecular weight epoxy(DER 662, DER 664) and a novolac epoxy(DEN 439), and the amount of DER 331 was not over 50% of the total epoxy components. Viscosity, cure time and mechanical properties of the vinylester resin were profoundly influenced by the quantity of reacted MAA, and the structure and molecular weight of the epoxy resin. Tensile and flexural strength appeared to be the greatest when DER 331 fraction was 30~40%.

• Journal of Ocean Engineering and Technology
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• v.23 no.4
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• pp.64-68
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• 2009

It has been observed that coated steel structures deteriorate more rapidly than the designed lifetime due to acid rain caused by air pollution, etc. Therefore, improving the corrosion resistance of anti-corrosive paint is very important in terms of safety and the economic point of view. In this study, the corrosion resistance of five kinds of anti-corrosive paints, including the Acryl, Fluorine, and Epoxy resin series, were investigated with electrochemical methods, such as corrosion potential measurements, polarization curves, diffusion limiting current density, etc. As a result, the corrosion resistance of the F101 specimen with the fluorine resin series was found to be superior to the other specimens, while E100 with the epoxy resin series also showed a somewhat good corrosion resistance. Furthermore, it was observed that the amount of water and oxygen entering the inner side of a painted film increased with an increase in immersion time, irrespective of the kind of resin series. However, the oxygen diffusion limiting current density of a specimen with good corrosion resistance was relatively decreased compared to other specimens, because of the difficulty of oxygen diffusion penetrating to the inner side of the film. Consequently it is suggested that we can qualitatively evaluate the corrosion resistance of an anti-corrosive paint by measuring the diffusion limiting current density as an electrochemical method.

• Restorative Dentistry and Endodontics
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• v.18 no.1
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• pp.55-72
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• 1993

The aim of this study was to compare the marginal leakage of class II light curing composite resin restoration according to filling methods. With using acid etching technique and dentin bonding agent, various methods were suggested to eliminate or reduce the marginal leakage. In this study, class II cavities were prepared in 100 extracted human premolars with cementum margin(1mm below the CEJ) and the teeth were randomly assigned to 5 groups of 20 teeth each. The teeth in group 1, 2, 3 and 4 were restored by direct filling methods using P-50 and Clearfil Photoposterior of 10 teeth each, but the method of insertion of the restorative materials varied with each group. And the teeth in group 5 were restored by inlay method using Kulzer Inlay and CR Inlay. Filling methods are as follows : Group 1 : The composite resin was inserted in one layer in the proximal box and one layer in the occlusal portion. Group 2 : Insertion was in two equally thick horizontal layers in the proximal box. Group 3 : Insertion was in two diagonally placed layers in the proximal box. Group 4 : The composite resin was inserted in the same way as in group 3 except that a glass ionomer liner was first placed on the axial wall and gingival floor. Group 5 : The teeth were restored by Inlay technique using dure cure resin cement. All the teeth were thermocycled, stained with 1 % methylene blue solution, sectioned mesiodistally, and scored for marginal leakage. To compare the marginal leakage, ANOVA and T-test were used in analysis. The following results were obtained : 1. In direct filling methods, there was no significant difference in marginal leakage at both occlusal and cervical margins. 2. In all groups, occlusal margin showed significantly less leakage than cervical margin. 3. In group using glass ionomer liner, there was no significant reduction of marginal leakage at the cervical margin. 4. The group restored by inlay method showed significantly less marginal leakage than groups restored by direct filling methods at both occlusal and gingival margins. 5. There was no significant difference in each group according to filling materials.

• Journal of the Korean Applied Science and Technology
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• v.36 no.4
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• pp.1128-1135
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• 2019

In this study, different types of polyether amines and H₁₂MDI were used to synthesize water dispersed urea resins, which can be applied to coating material on the concrete slabs for bicycle road using the ordinary application equipments. The concentrations of several polyether amines with different molecular weights and the number of amine functionality were varied to set up the optimal condition for water dispersed urea resin preparation with both an excellent tensile strength and an elongation. In addition, the effect of DMPA[2,2-Bis(hydroxymethyl)propanoic acid] concentration on the storage stability of the water dispersed urea resin was also investigated. The formation of urea bonds from isocyanate and polyether amines was confirmed through FT-IR ATR spectroscopy. From the mechanical properties of urea resins, PU-4 and PU-6, which were prepared with both diamines and triamine of different molecular weights and number of functionality, showed the tensile strength of 10.5 N/㎟ and 12.7 N/㎟, respectively and the elongation of 1165 % and 969%, respectively. Among the water dispersed urea resin synthesized with different contents of DMPA, PU-6 showed the highest mechanical properties, a tensile strength of 14.2 N/㎟ and an elongation of 993%. In addition, the water dispersion state of this PU-6 was the most stable even after 8 weeks.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.3
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• pp.221-230
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• 2006

Recently, the need for esthetic results has increased the interest for all-ceramic crown prosthesis. Furthermore, the development of zirconium core via CAD/CAM system has allowed the all ceramic restorations to be applied to almost all fixed prosthesis situations. But, the increased strength has been reported to increase in proportion with the bond strength of cement, and recently, the tribochemical system which increases the bond strength through, silica coating and silanization has been introduced. The purpose of this study was to compare the $Rocatec^{TM}$ system and $CoJet^{TM}$ system with the traditional acid etching and silanization method of the irconium based ceramic. The surface character was observed via SEM(X2000), and the bond strength with the resin cement were measured. 50 In-Ceram Zirconia (Adens, Korea) discs were fabricated and embedded in resin, group 1 was treated with glass-bead blasting and cleaning, group 2 was treated with 20% HF for 10 minutes and silanized, group 3 was treated with the $Rocatec^{TM}$ system, and group 4 was treated with the $CoJet^{TM}$ system. Each group was comprised of 10 specimens. The specimens were cemented to a $3mm{\times}5mm$ resin block with Super-Bond C&B. The shear bond strength was measured with the $Instron^{(R)}$ 8871 at a crosshead speed of 0.5mm/min. The results were as follows. 1. According to SEM results, there were little difference between group 1 & group 2, but in group 3 and 4, silica coating was detected and there was increase in surface roughness. 2. The shear bond strength decreased in the order of group 3(46.28MPa), group 4(42.04MPa), group 2(31.56MPa), and group 1(27.46MPa). 3. There was significant differnce between group 1&2 and group 3&4(p<0.05). From the results above, it can be considered that the conventional method of acid etching and silane treatment cannot increase the bond strength with resin cements, and that by applying the tribochemical system of $Rocatec^{TM}$ system and $CoJet^{TM}$ system, we can achieve a stronger all ceramic restoration. Further studies on surface treatments to increase the bond strength are thought to be needed.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.3
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• pp.319-324
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• 2003

Statement of problem. Adhesives in dentistry playa major role in the success of restorative treatments. In the treatment of all ceramic restoration it is needed to find the adequate bond strength between enamel and dentin. Purpose. The purpose of this study was to evaluate shear bond strength of resin cement bonded to extracted human uncut enamel, cut enamel, and dentin in vitro. Material and methods. Ten freshly extracted anterior teeth without any previous restorative treatments were chosen. The extracted teeth were embedded in PMMA cold acrylic in the shape of a cylinder, 25 mm in diameter by 25 mm in height. The bonding system used was as follow: Uni-Etch (32% phosphoric acid), One-Step adhesive, Duolink resin cement. The specimens were acid etched and rinsed with water. Two layers of One-Step adhesive were coated with a disposable brush on the uncut enamel. VIP curing light at $500mV/cm^2$ was used to cure the adhesive. For cut enamel shear bond test, the specimen used for uncut enamel was further reduced approximately $0.3{\sim}0.5mm$ using a laminate preparation diamond bur (0.3 mm in depth). The specimens were subsequently treated with 320-grit SiC paper followed by 600-grit SiC paper and cleaned with distilled water. The bonding procedure on the cut enamel was same as uncut enamel bonding procedure. For dentin bonding test, the specimen used for cut enamel was further reduced approximately $0.5mm{\sim}1.0mm$ using a laminate preparation diamond bur (0.5 mm in depth of diamond cutting). The amount of reduction was evaluated with the silicone mold. The specimens were subsequently treated with 320-grit SiC paper followed by 600-grit silicon carbon paper and cleaned in distilled water. The bonding procedure on the dentin was same as uncut enamel bonding procedure. All samples were mounted and secured on the Ultradent shear bond test sample holder, and Ultradent restricted shear bond testing device was used with Universal Instron machine until fracture. Analysis of variance (ANOVA) test was performed comparing the result at P<0.05. Multiple comparison (Tukey) was used to compare each groups. Result. The result showed that the mean value in shear bond strength of resin cement bonded to uncut enamel, cut enamel and dentin were 27.04 Mpa, 30.25 Mpa and 26.39 Mpa with respect. Conclusion. Within the limitation of this study, the mean value of the shear bond strength of cut enamel was higher than those of uncut enamel or dentin. However there existed no statistical differences between three different human dentition substrates due to increased adhesive characteristics.

• The korean journal of orthodontics
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• v.27 no.5 s.64
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• pp.839-852
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• 1997

It has been submitted that different ion solutions containing sulfate induce crystal growth and might substitute conventional acid etching for pretreatment of enamel in orthodontic bonding(${\AA}rtun$ et al., Am. J. Orthod. 85, 333, 1984). This investigation was designed to evaluate the relevance of crystal growth on the enamel surface as an alternative to conventional acid etching in direct bonding of orthodontic brackets. Annexing Li2SO4, MgSO4, K2SO4 respectively in the solution with $25\%$ polyacrylic md 0.3M sulfuric acids were employed to enhance the crystal growth. Human bicuspids were treated with various parameters as combinations of crystal growth and glass ionomer cement, crystal growth and orthodontic resin, acid etching and orthodontic resin for an investigative purpose. Crystal growth solution containing MgSO4 showed the highest shear bond strength(15.6MPa) within the groups of bonding brackets with glass ionomer cement(p<0.01). Bonding with glass ionomer cement on the surface of crystal growth demonstrated higher shear bond strength than with orthodontic resin(p<0.001). Bonding with glass ionomer cement on the surface treated with crystal growth solution containing MgSO4 or K2SO4 was not different shear bond strength statistically from bonding with orthodontic resin on the acid-etched surface. It suggests that bonding brackets with glass ionomer cement on the surface treated with crystal growth solution containing MgSO4 or K2SO4 is a potential alternative to bonding with resin on the acid etched sufrace.