• The korean journal of orthodontics
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• v.25 no.5 s.52
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• pp.605-611
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• 1995

The purpose of this study was to evaluate effects of time on shear bond strengths of a light-cured glass ionomer cement and chemically cured resin cement to enamel, and to observe the failure patterns of bracket bondings. Shear bond strength of a light-cured glass ionomer cement were compared with that of a resin cement. Metal brackets were bonded on the extracted human bicuspids. Specimens were subjected to a shear load(in an Instron machine) after storage at room temperature for 5 and 15 minutes; after storage in distilled water at $37^{\circ}C$ for 1 or 35 days. The deboned specimens were measured In respect of adhesive remnant index. The data were evaluated and tested by ANOVA, Duncan's multiple range test, and t-test, and those results were as follows. 1. The shear bond strength of light-cured glass ionomer cement is higher than that of resin cement at 5 and 15 minutes. 2. The shear bond strengths of both light-cured glass ionomer cement and resin cement increase with time. There was no significant difference in those of both 1 day group and 35 day group 3. Light-cured glass ionomer cement is suitable as orthodontic bracket adhesives

• The korean journal of orthodontics
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• v.35 no.6 s.113
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• pp.443-450
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• 2005

This study was performed to compare the shear bond strength of orthodontic adhesive to amalgam according to different light sources (halogen-based light and light emitting diode (LED)) and amalgam surface treatments. Ninety extracted human premolars were randomly divided into 6 groups (4 experimental and 2 control groups) of 15 by light sources and surface treatments. Orthodontic brackets were bonded and shear bond strength was measured with an Instron universal testing machine. The findings were as follows: The bond strength of adhesive to amalgam surface was 3-5.5 MPa which was lower than that of acid-etched enamel (19 MPa) control. In the sandblasted amalgam surface, the shear bond strength of the halogen light group was higher than that of the LED group (p < 0.05) but. in the non-treated amalgam surface. there was no significant difference in the shear bond strength according to the light sources (p> 0.05). Within the same light source. sandblasting had no significant effect on the shear bond strength of the adhesive bonded to amalgam surface (p > 0.05). There was no significant difference in shear bond strength according to the light sources in acid-etched enamel control groups. This results suggest that there can be a limit in using light curing adhesives when brackets are bonded to an amalgam surface. Additional clinical studies are necessary before routine use of halogen light and LED light curing units can be recommended in bonding brackets to an amalgam surface.

• Journal of Adhesion and Interface
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• v.16 no.2
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• pp.69-75
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• 2015

Stone board for the rock bed was needed to reduce weight using thin thickness and reinforced materials. In this work, stone/wood board for rock bed was studied. Stone and wood were attached to reduce total weight of stone for rock bed. For reinforcing wood heat treatment method was used to change surface and mechanical properties. Mechanical strength of heat treated wood increased more than neat condition. The optimum heat treatment condition was set on $100^{\circ}C$ under tensile, flexural loads whereas surface energy was also obtained by contact angle measurement. Optimum adhesive condition was to get the maximum adhesion between stone and wood. Lap shear test was performed for stone/wood board with different adhesives such as amine type epoxy, polyurethane, chloro-rubber and vinyl chloride acetate type. Fracture surface of lap shear test was shown at wood fracture part on stone using amine type epoxy adhesive. It was found that for high adhesion between stone and wood the optimum adhesive was epoxy type for the rock bed.

• Elastomers and Composites
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• v.44 no.3
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• pp.196-208
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• 2009

Sophisticated polymeric materials with 'responsive' properties are beginning to reach the market. The use of reversible, noncovalent interactions is a recurring design principle for responsive materials. Recently developed hydrogen-bonding units allow this design principle to be taken to its extreme. Supramolecular polymers, where hydrogen bonds are the only force keeping the monomers together, form materials whose (mechanical) properties respond strongly to a change in temperature or solvent. In this review, we describe some examples of hydrogen-bonded supramolecular polymers that can be utilized for self-healing materials. Synthesis of a rubber-like material that can be recycled might not seem exciting. But one that can also repeatedly repair itself at room temperature, without adhesives, really stretches the imagination. Autonomic healing materials respond without external intervention to environmental stimuli in a nonlinear and productive fashion, and have great potential for advanced engineering systems.

• The korean journal of orthodontics
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• v.30 no.4 s.81
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• pp.483-490
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• 2000

The dental gold alloy shows a lower bond strength than the natural teeth in bracket bonding, and this can be a possible source of subsequent bond failure. This study aims to evaluate the effect of various gold alloy surface treatment techniques on shear bond strength between the orthodontic adhesives and the gold alloy and to find ways of increasing the bond strength. Two hundred and forty specimens made of the dental fold alloy were divided into twelve groups based on the combination of surface treatment methods(non-surface treatment, sandblasted, sandblasted plus tin-plated, and sandblasted plus intermediate adhesive) and adhesive systems (Ortho-one, Panavia 21, Superbond C&B). The specimens with bonded brackets were placed in distilled water at $37^{\circ}C$ for 24 hours and shear bond strength was measured by a universal testing machine. The results were as follows: 1. All surface-treated groups showed a significantly higher shear bond strength than non-surface-treated groups. 2. The sandblasted plus tin-plated group showed a significantly higher shear bond strength than the sandblasted group only when Panavia 21 was involved. 3. The sandblasted plus intermediate adhesive group showed a significantly higher shear bond strength than sandblasted group regardless of the type of adhesive used. 4. Of the three resin adhesive types, the Superbond C&B showed the highest bond strength, followed by Panavia 21 and Ortho-one. These findings suggest that a combination of sandblasting and intermediate resin treatment is desirable in order to enhance bracket bond strength regardless of adhesive types.

• Journal of Adhesion and Interface
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• v.23 no.2
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• pp.25-32
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• 2022

There has been a growing demand for water based-type PSA due to environmental regulations for solvent-type PSA. And accordingly, there is a growing expectation as well for tackifiers used to compensate for the problem of deterioration of physical properties. Therefore, In this study, water-based tackifiers were synthesized by changing the contents of hard and functional acrylic monomers CHMA, IBOA, and AA. And these were added to the pressure-sensitive adhesive at 10 phr and their physical properties were compared. Tackiness slightly decreased as CHMA increased and IBOA decreased. Since the intermolecular bonding force increased due to the increase in AA content, the lower the AA content showed better results. Peel strength increased as the tackifiers were added because the fluidity of the polymer chain increased. And higher AA content showed better results because more hydrogen bonds were formed. The holding power tended to decrease as CHMA increased because the content of IBOA relatively decreased which has a large influence on the holding power. And higher AA content showed better results.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.4
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• pp.619-627
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• 2008

The objective of this study was to compare the microleakage of five adhesive systems in the enamel and dentin of permanent teeth. Class V cavity preparations with occlusal margins in enamel and gingival margins in dentin were prepared on both buccal and lingual surfaces of 25 extracted human molar teeth. The tested adhesives were: Adper Scotchbond Multi-purpose Plus Adhesive (SM), Adper Single bond 2 (SB), Clearfil SE Bond (SE), Adper Prompt L-Pop (PL) and G-Bond (GB). The results were as follows: 1. At the enamel margins, PL showed the highest leakage value(0.85), and others showed values of SB(0.55), GB(0.50), SM(0.35) and SE(0.25) in decreasing order. There were statistically significant differences in PL vs. SM and PL vs. SE(p<0.05). 2. At the dentin margins, GB showed the highest leakage value(2.10), and others showed values of SE(1.45), PL(1.40), SB(1.05), SM(0.70) in decreasing order. There were statistically significant differences in GB vs. SB and GB vs. SM(p<0.05). 3. Dentin margins showed high dye penetration rate than enamel margins in all material tested groups and there were statistically significant differences for SE, PL and GB.

• Journal of Korean Society of Forest Science
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• v.60 no.1
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• pp.51-57
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• 1983

Properties and glue shear strength of each water soluble rues-phenol copolymer adhesive and phenolic resin adhesive were examined as a high temperature curing binder through the manufacture of plywood made of Kapur veneer. The former has different molar ratio and the latter was made from different catalyst method. The results are summarized as follows: 1) Specific gravities of air dried plywood manufactured from each adhesive ranged from 0.67 to 0.82 and their moisture contents met the K.S. standard 2) In dry and wet shear strength, adhesives with 60 percent of non volatile content showed higher values than those with 50 percent except phenolic resin. Urea-phenol copolymer resin with 20 percent of phenol content exhibited the highest, and that with 70 percent the lowest. Filling effect of wood flour on the bonding strength is great in urea-phenol copolymer resin with more than 50 percent of phenol content, especially significant in 50 percent of non volatile content including alkali catalyst phenolic resin. Alkali and acid catalyst methods were the highest among the adhesive manufacture methods. In wet strength, urea resin belongs to the lowest group. 3) In glue shear strength after boiling and drying test, no method for manufacturing phenolic formaldehyde resin adhesive was stronger than alkali and acid catalyst methods. Phenolic resin made from alkali catalyst method needs a wood flour filler to improve the bonding quality. Urea-phenol copolymer resin with 10 percent of phenol content showed the reasonable water resistance.

• The korean journal of orthodontics
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• v.34 no.5 s.106
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• pp.439-447
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• 2004

The purpose of this study was to investigate the influence of water, saliva and blood contamination on the bonding strength of metal brackets with a self-etching primer/adhesive to enamel. Ninety-six extracted human teeth were divided into four groups. The brackets were bonded to enamel with a self- etching primer (3M/Unitek Dental Products. Monorovia California) according to one of four protocols. The teeth were bonded in a dry condition (group D) or in contamination with distilled water (group W), artificial saliva (group S). or fresh human blood (group B) Shear bond strengths were tested using an Instron Universal testing machine. After debonding. bracket and tooth surfaces were examined with a stereomicroscope. In each group, four samples were selected and examined with a Scanning electron microscope of the prepared enamel surface and resin-enamel interlace. The results obtained were summarized as follows: Shear bond Strength if group D $(15.22{\pm}2.86MPa)$ and W $(15.20{\pm}3.85 MPa)$ Were higher than in group B$(12.56{\pm}2.94MPa)$ (p<0.05). There were no statistical differences in the shear bond strengths between groups D. W and S (p>0.05). There was a tendency to have less residual adhesive remaining on the enamel surfaces of group B than group D. The SEW morphology of group D and W showed a more roughened etching pattern than group S and B. Water or saliva contamination on bending of orthodontic brackets with Transbond plus self etching primer had almost no influence on bond strength In this study, the blood contaminated group showed the lowest bond strength, but it was above the clinically acceptable bond strength (5.9-7.8 MPa, Reynold, 1975). The results of this study suggest that acceptable clinical bond strengths can be obtained in wet conditions when self-etching adhesives are used.

• Journal of Korean Society of Forest Science
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• v.51 no.1
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• pp.41-50
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• 1981

The purpose of this study was to evaluate the substitutional possibility of new extender instead of wheat flour, which is extending for plywood adhesives in Korea. As the extending materials corn stalk, pine bark, Pitch and Korean pine leaves, wheat, or wood flour were selected and prepared for the extending powders, dried at $103{\pm}2^{\circ}C$ during 24 hours in the drying oven, followed by being pulverized into 60-100 mesh powder. The extenders were mixed with urea formaldehyde resin in the ratio of 5, 10, 15 or 20%. After plywoods were manufactured by the above extended ratios, dry and wet shear strength and wood failures were analyzed and discussed. The results at the study may be summarized as follows ; 1. In urea formaldehyde resin dry shear strength in plywood extended by wheat flour showed the highest value. 2. Among the extenders in 10 and 20% extension of urea formaldehyde resin wet shear strength of wood flour was higher than that of wheat powder. They had no significant difference statistically. 3. Among the extenders of 5% extension of water soluble phenol formaldehyde resin dry shear strength of plywood extended by Korean pine leaf powder showed the highest value, while wheat powder showed the highest value among 10, 15 and 20% extentions. 4. In water soluble phenol formaldehyde resin the best results of wet shear strength showed in wheat powder. 5. Among the extenders in 15 and 20% extension of water soluble phenol formaldehyde resin, dry and wet shear strength in plywood of corn stalk powder were the highest value next to wheat powder.