• Journal of the Korea Concrete Institute
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• v.28 no.6
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• pp.637-646
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• 2016

In this study, slant shear tests for the prism specimens strengthened with ultra-high performance fiber reinforced concrete (UHPFRC), normal- and high-strength concrete were performed to evaluate the interfacial shear strength between old and new concrete substrate. Test parameters are the roughness of surface, concrete strength, and fiber volume fraction of UHPFRC. The surface of the concrete was roughened by shot blasting. Test results showed that the adhesion bond resistance of the specimen with a roughened surface was very large compared to that of the specimen with a smooth surface. In addition, the interfacial shear strength appeared to be affected by the concrete strength rather than the fiber volume fraction. For the roughened surface by shot-blasting method, interfacial shear resistance exceeded the upper limit which is presented in current design codes even if the shear-friction reinforcements are not provided. Based on the test results, it is applicable to use the current concrete design codes to achieve the shear-friction design for the interface between conventional concrete and UHPFRC. However, for the surface which is not processed, it would be appropriate to provide additional shear-friction reinforcement.

• Journal of the Korea Concrete Institute
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• v.19 no.3
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• pp.333-339
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• 2007

The purpose of this study was to enhance bond performance between recycled PET (polyethylene telephthalat) fiber and cement composites through hydrophilic treatment using maleic anhydride grafted polypropylene(mPP). The mPP with various concentration of 0%, 5%, 10%, 15% and 20% to determine effect on bond behavior of recycled PET fiber were applied as experimental variables. Dog bone shaped specimens according to JCI SF-8 was applied to evaluate the bond strength and pullout energy. The results showed increased bond strength and pullout energy as concentration of mPP. Concentration of 15% mPP showed the most effective results while 20% showed reduced performance results. Because 15% mPP ensures perfect coating while 20% makes thick coating area that resulted in crack propagation and consequent separation of PET fiber and coated area during pullout load occurred. Enhancement mechanism of bond performance of recycled PET fiber and cement composites with each concentration of mPP could be conformed through investigation of microstructure of fiber surface.

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.470-478
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• 1997

The purpose of this study was to investigate the effects of moistening mechods of dentin on the morphologic states of hybrid layers and on the interfacial bond strength between dentin and composite. Specimens were divided into 6 groups based on the surface moistening methods and materials used. After the dentin surface was conditioned with 10 % phoporic acid and irrigated: 1. The dentin surface was dried. Then bonding agent and composite were applied. 2. The dentin surface was blot-dryed. Then primer, bonding atent and composite were applied. 3. The dentin surface was dryed first. Within 20 seconds, the surface was rewetted, then primer, bonding agent and composite were applied. 4. The dentin surface was dryed. Then primer, bonding agnent and composite were applied. 5. The dentin surface was dryed first. Atter 24hrs, the surface was rewetted, and then primer, bonding agent and composite were applied. 6. The surface was conditioned with NaOCl for 5min. Then primer, bonding agent and composite were applied. To reveal the hybrid layer, scanning electron microscopy was used after the samples were ion beam etched. The shear bond strength of each group was tom pared by ANOVA. In groups 2, 3 and 4, the hybrid layer was clearly visible, but the width was more limited in group 4. In group 1 and 5, the hybrid layer was not found, and a gap was formed between dentin and composite. In group 6, the hybrid layer was not found, but the interface between the dentin and composite was intimate. The shear bond strength of each group was as follows: Group 1 : 4MPa, Group 2 : 14MPa, Group 3 : 12MPa, Group 4 : 14MPa, Group 5 : 5MPa, Group 6 : 9MPa.

• Restorative Dentistry and Endodontics
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• v.29 no.2
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• pp.170-176
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• 2004

Objectives : In the unique metal iris method. the developing interfacial gap at the cavity floor resulting from the cavity wall property during polymerizing composite resin might affect the nominal shear bond strength values. The aim of this study is to evaluate that the iris method reduces the cohesive failure in the substrates and the cavity wall property effects on the shear bond strength tests using iris method. Materials and Methods : The occlusal dentin of 64 extracted human molars were randomly divided into 4 groups to simulate two different levels of cavity wall property (metal and dentin iris) and two different materials ($ONE-STEP^{\circledR}$ and $ALL-BOND^{\circledR}$ 2) for each wall property. After positioning the iris on the dentin surface. composite resin was packed and light-cured. After 24 hours the shear bond strength was measured at a crosshead speed of 0.5 mm/min. Fracture analysis was performed using a microscope and SEM. The data was analyzed statistically by a two-way ANOV A and t-test. Results : The shear bond strength with metal iris was significant higher than those with dentin iris (p＝0.034). Using $ONE-STEP^{\circledR}$, the shear bond strength with metal iris was significant higher than those with dentin iris (p＝0.005), but not in $ALL-BOND^{\circledR}$ 2 (p＝0.774). The incidence of cohesive failure was very lower than other shear bond strength tests that did not use iris method. Conclusions：The iris method may significantly reduce the cohesive failures in the substrates. According to the bonding agent systems. the shear bond strength was affected by the cavity wall property.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.4
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• pp.595-607
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• 1999

The purpose of this in vitro study was to evaluate the efficacy of self-etching primer which was developed to simplify the bonding procedures by measuring the shear bond strength and observing the interfacial morphology. 90 flat dentinal surfaces were prepared by grinding the buccal and lingual areas of caries-free human deciduous molars. After bonding of composite resin to sample surfaces according to the manufacturer's direction and thermocycling, shear bond strengths were measured using Universal testing machine(Instron). Another groups of specimens were treated by hydrochloric acid to secure the resin only and those tags were evaluated under SEM for their length and forms and the morphology of the bonding sites were also observed. The result as follows. 1. Group III showed higher shear bond strength than group I and II but no statistically significant difference was founded between group I and II(p>.05). 2. Adhesive failure was predominant in group II whereas dentin detachment was the main failure pattern in group I and III. 3. Relating long resin tags of $100-200{\mu}m$ were observed in samples of all groups under SEM. In group I, homogeneously long resin tags were arranged rather tight whereas rather loosely arranged resin tags of various length were found in group II. Lateral branching of resin tags was the characteristic finding observed in group III.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.197-212
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• 1998

The purpose of this study was to evaluate the effects of fluoride application on the aspect of shear bond strength of three aesthetic restorative materials to dentin. One light-cured composite resin(Palfique Esterite) and two light-cured glass ionomer cements(Fuji II LC and Compoglass)were used in this study. 120 permanent molars were used for this study. The teeth were extracted due to the origin of periodontal disease. The crowns of all teeth were removed, and the remaining roots were embedded in epoxy resin. The mesial or distal surfaces of roots were ground flat to expose dentin and polished on wet 320-, 400-, and 600 grit SIC papers for a total of 120 prepared flat root dentin surfaces. The prepared samples were divided into six groups. Group 1, 3, and 5 were control groups and group 2, 4, and 6 were experimental groups. Sixty samples for experimental groups were treated with 2% NaF solution for 5 minutes. Group 1 and 2 were bonded with Plafique Esterite, group 3 and 4 were bonded with Fuji II LC, and group 5 and 6 were bonded with Compoglass. After 24 hours water storage at $37{\pm}1^{\circ}C$, all samples were subjected to a shear to fracture with Instron universal testing machine(No.4467) at 1.0 mm/min displacement rate. Dentin surfaces treated with each conditioners before bonding and interfacial layers between dentin and aesthetic restorative materials were observed under Scanning Electron Microscope(Hitachi S-2300) at 20Kvp. The data were evaluated statistically at the 95% confidence level with ANOVA test. The result were as follows; 1. Among the control groups, group 1 showed strongest bond strength and group 3 showed weakest. 2. Among the experimental groups, group 2 showed strongest bond strength and group 6 showed weakest. 3. Statistical analysis of the data showed that pretreatment of dentin with 2% NaF solution significantly decreased the bond strength of three aesthetic restorative materials to dentin(P<0.05). 4. SEM findings of fluoride treated dentin surfaces (2, 4, 6 group) demonstrated dentin surfaces covered with fluoridated reaction products. 5. Except group 4 and 6, resin tags were formed in all groups.

• Proceedings of the Korean Fiber Society Conference
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• 1997.04a
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• pp.26-31
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• 1997

유리섬유/nylon 6 복합재료의 계면결합강도를 증가시키기 위하여 r-APS(r-Aminopropyltriethoxysilane)로 유리섬유의 표면을 처리 하였다. 이때 표면처리의 최적 조건을 찾기위해서 처리후 기기분석과 계면결합강도 측정 등을 하였다. 농도, pH, 처리시간, 온도를 변화시키면서 표면처리를 한 후 흡착량을 살펴본 결과 처리 농도에 의해서는 흡착량이 단조증가하였으며 처리시간에 따라서는 5분정도에서, 처리온도에 의해서는 30C 부근에서 최대 흡착량을 보였다. 또한 pH에 따른 흡착량은 silane의 고유 pH인 10.5부근에서 최대치를 나타냈다. FR-IR 분석에 의하면 NH2의 NH3 bending mode가 1607cm-1, 1575cm-1에서 나타났으며 SiOH의 SiO band는 960cm-1에서 나타났다. XPS를 통해서는 N ls와 Si 2p의 존재를 확인할 수 있었다. 표면처리된 유리섬유와 matrix인 nylon 6를 이용해 단섬유내장시편을 만들어 fragmentation test를 한 결과 계면결합강도는 약 5분의 처리시간과 1%(wt%)의 농도에서 최대값을 보였다.

• Journal of the Korean institute of surface engineering
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• v.28 no.4
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• pp.219-224
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• 1995

The peel adhesion and plastic deformation in Cu-Cr alloy films, sputter-deposited onto polyimide films, have been studied as a function of Cr content in the film. The adhesion strength has been measured by T-peel test and the amount of plastic deformation in the peeled metal strip was determined qualitatively by XRD technique. Peel adhesion strength has a maximum in the film containing 22-33wt.% Cr and the peel strength of pure Cr film is lower than the maximum. The film having the highest peel strength is deformed most heavily. The effect of Cr content on the peel strength is discussed in terms of the interfacial bond strength and mechanical properties of Cu-Cr alloy film.

• Proceedings of the KWS Conference
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• 1996.05a
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• pp.6-9
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• 1996

The Joining of copper rod and zirconia tube was carried out in Ar gas atmosphere. There are two type of the joining. The one is the reaction bond consisting of Cu and zirconia was dominated by surface reaction wi th a undetctable very thin layer. It was found that copper elements were diffused to zirconia side, but that most of Z $r^{4+}$ ions were not diffused to copper side. This result means application of a DC voltage to migrate oxygen to the copper/zirconia interface can oxidize metal at the copper /zirconia interface, and the bonding reaction between zirconia and copper oxide may occur. The other is the reaction bonding was dominated by interdiffusion with a very thick interface layer. This result means application of a DC voltage can reduce zirconia at the interface. The bonding reaction is to be an alloying between Zr and Cr.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.13 no.1
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• pp.15-28
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• 1987

Silica spheres were prepared by interfacial reaction method. Factors in-fluencing to the mean particle size and specific surface area of silica spheres were investigated. The experiment about the surface modification of silica spheres was carried out. It was observed that silica spheres have characteristics of the spherical shape with the vacancy in the inner side, high surface area, and reaction tendency by many silanol group. The mean particle size of silica spheres is dependent on the surfactant concentration and W/O ratio. The specific surface area is influenced by SiO2/Na2O mole ratio in sodium silicate. Silica spheres coated with titanium dioxide or zirconium dioxide improve the UV protection effect. Titanate and silane coupling agent make chemical bond with silica surface and improve the organophile and the dispersibility of silica spheres.