• Journal of Conservation Science
• /
• v.34 no.5
• /
• pp.379-385
• /
• 2018

This study examined the condition of degraded plastic artifacts and conducted materials assessments for conservation treatment. The properties and bond characteristics of five types of adhesives(EVA, PVAc, Cyanoacrylate) were evaluated to select the adhesive most suitable for conservation treatment. The degradation of plastic artifacts caused cracks, peelings, and surface warping. According to the FT-IR analysis, the synthetic resin used in the artifact was estimated to EVA type. The properties of the adhesives were evaluated through acidity, and hardness measurements. The results showed that acidity varies with the type of adhesive, and that the hardness of PVAc was higher than those of EVA. On comparing the bond characteristics of the samples after artificial degradation, it was found that PVAc and Cyanoacrylate increased the chromaticity and hardness of the samples, while EVA was the most stable with relatively little change. Thus, EVA was confirmed to be the most suitable materials for conservation treatment of degraded plastic artifacts. In this study, as the experiment of treatment materials based on actual artifact, it is expected that it could be used a basis research for conservation treatment of plastic artifacts.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.30 no.1
• /
• pp.54-60
• /
• 2003

This study evaluated the influence of chemomechanical caries removal agent $Carisolv^{TM}$(MediTeam, Sweden) for composite resin adhesion to sound human permanent and primary dentin. The buccal/labial surfaces of 80 permanent molars and 80 primary incisors were used. Four types of adhesives and one composite resin were used; AQ Bond(Sun Medical, Japan), Clearfil SE Bond(Kuraray, Japan), Single Bond(3M, USA), Scotchbond Multi-Purpose(3M, USA) and Z100(3M, USA). One drop of $Carisolv^{TM}$(MediTeam, Sweden) was pretreated on the dentin for 0 second(control) and 60 seconds. The specimens were thermocycled for 1,000 times in baths kept 5 degrees C and 55 degrees C with a 30 seconds dwell time. Shear bond strengths were tested and the data was statistically analyzed using one-way ANOVA with subsequent post hoc Scheffe test at p<0.05. $Carisolv^{TM}$ treatment significantly decreased the shear bond strength. Shear bond strength of permanent dentin was significantly higher than that of primary dentin. Clearfil SE Bond treatment groups showed the highest shear bond strength and AQ Bond treatment groups showed the lowest shear bond strength.

• Korean Chemical Engineering Research
• /
• v.46 no.3
• /
• pp.619-625
• /
• 2008

The effects of thermal cycling on residual stresses in both inorganic passivation/insulating layer that is deposited by plasma enhanced chemical vapor deposition (PECVD) and organic thin film that is used as a bonding adhesive are evaluated by 4 point bending method and wafer curvature method. $SiO_2/SiN_x$ and BCB (Benzocyclobutene) are used as inorganic and organic layers, respectively. A model about the effect of thermal cycling on residual stress and bond strength (Strain energy release rate), $G_c$, at the interface between inorganic thin film and organic adhesive is developed. In thermal cycling experiments conducted between $25^{\circ}C$ and either $350^{\circ}C$ or $400^{\circ}C$, $G_c$ at the interface between BCB and PECVD $ SiN_x $ decreases after the first cycle. This trend in $G_c$ agreed well with the prediction based on our model that the increase in residual tensile stress within the $SiN_x$ layer after thermal cycling leads to the decrease in $G_c$. This result is compared with that obtained for the interface between BCB and PECVD $SiO_2$, where the relaxation in residual compressive stress within the $SiO_2$ induces an increase in $G_c$. These opposite trends in $G_cs$ of the structures including either PECVD $ SiN_x $ or PECVD $SiO_2$ are caused by reactions in the hydrogen-bonded chemical structure of the PECVD layers, followed by desorption of water.

• Restorative Dentistry and Endodontics
• /
• v.25 no.2
• /
• pp.243-253
• /
• 2000

The purpose of this in vitro study was to evaluate dentin bonding by two different dentin bonding systems(DBS) using acetone based primer or adhesive [All Bond 2(AB2), One Step(OS)] when they were applied by wet or dry bonding technique. Morphology of resin-dentin interface and hybrid layer thickness(HLT) were investigated using Confocal Laser Scanning Microscope(CLSM) and compared to shear bond strength(SBS). 72 extracted sound human molars were randomly divided into 4 groups of 18 teeth each - Group 1.(AW); AB2 by wet bonding. Group 2(AD); AB2 by dry bonding. Group 3.(OW); OS by wet bonding, Group 4.(OD); OS by dry bonding. In 6 teeth of each group, notch-shaped class V cavities(depth 2mm) were prepared on buccal and lingual surface at the cementoenamel juction(12 cavities per group). To obtain color contrast in CLSM observation, bonding resins of each DBS were mixed with rhodamine B and primer of AB2 was mixed with sodium fluorescein. Prepared teeth of each group were treated with AB2, OS, respectively according to the manufacturer's instructions except for dentin surface moisture treatment after acid etching. In group 1 and 3, after acid etching, excess water was removed with wet tissue(Kimwipes), leaving consistently shiny, visibly hydrated dentin surface. In group 2 and 4, dentin surface was dried for 10 seconds at 1 inch distance. The treated teeth were then packed with composite resin(${\AE}$litefil) and light-cured. 12 microscopic samples($60{\sim}80{\mu}m$ thickness) of each group were obtained after longitudinal section and grinding(Exakt cutting and grinding system). Morphological investigation of resin-dentin interface and HLT measurement using CLSM were done. For measurement of SBS, remaining 12 teeth of each group were flattened occlusally to remove all enamel and grinded to 500 grit SiC(Pedemet Specimen Preparation Equipment). After applying DBS on the exposed dentin surface, composite resin was applied in the shape of cylinder, which has 5mm diameter, 1.5mm thickness, and light cured. SBS was measured using Instron with a crosshead speed of 0.5mm/min. It was concluded as follows, 1. HLT of AW(mean: $2.59{\mu}m$) was thicker than any other group, and followed by AD, OW, OD in descending order(mean; 2.37, 2.28, $1.92{\mu}m$). Only OD had statistically significant differences(p<0.05) to AW and AD. 2. There were intimate contact of resin and dentin at the interface in wet bonding groups, but gaps or irregular interfaces were observed in dry bonding groups. 3. The length, diameter, density of resin tags were various even in the same group without significant differences between groups and lots of adhesive lateral branches were observed. 4. There were no statistically significant difference of SBS between AB2 and OS, but SBS of wet bonding groups were significantly higher(p<0.05) than dry bonding groups. 5. There were no consistent relationships between HLT and SBS.

• Steel and Composite Structures
• /
• v.3 no.6
• /
• pp.421-438
• /
• 2003

Aging and deterioration of existing steel structures necessitate the development of simple and efficient rehabilitation techniques. The current study investigates a methodology to enhance the flexural capacity of steel beams by bonding Glass Fibre Reinforced Plastic (GFRP) sheets to their flanges. A heavy duty adhesive, tested in a previous study is used to bond the steel and the GFRP sheet. In addition to its ease of application, the GFRP sheet provides a protective layer that prevents future corrosion of the steel section. The study reports the results of bending tests conducted on a W-shaped steel beam before and after rehabilitation using GFRP sheets. Enhancement in the moment capacity of the beam due to bonding GFRP sheet is determined from the test results. A closed form analytical model that can predict the yield moment as well as the stresses induced in the adhesive and the GFRP sheets of rehabilitated steel beam is developed. A detailed finite element analysis for the tested specimens is also conducted in this paper. The steel web and flanges as well as the GFRP sheets are simulated using three-dimensional brick elements. The shear and peel stiffness of the adhesive are modeled as equivalent linear spring systems. The analytical and experimental results indicate that a significant enhancement in the ultimate capacity of the steel beam is achieved using the proposed technique. The finite element analysis is employed to describe in detail the profile of stresses and strains that develop in the rehabilitated steel beam.

• The korean journal of orthodontics
• /
• v.41 no.1
• /
• pp.51-58
• /
• 2011

Objective: To evaluate the shear bond strength (SBS), fracture mode, wire pull out (WPO) resistance and microleakage between low-shrinking and conventional composites used as a lingual retainer adhesive. Methods: A total of 120 human mandibular incisor teeth, extracted for periodontal reasons, were collected. Sixty of them were separated into two groups. To determine the SBS, either Transbond-LR (3M-Unitek) or Silorane (3M-Espe) was applied to the lingual surface of the teeth by packing the material into standard cylindrical plastic matrices (Ultradent) to simulate the lingual retainer bonding area. To test WPO resistance, 20 samples were prepared for each composite where the wire was embedded in the composite materialand cured. Then tensile stress was applied until failure of the composite occurred. The remaining 60 teeth were divided into two groups and multi-stranded 0.0215-inch diameter wire was bonded with the same composites. Microleakage was evaluated by the dye penetration method. Statistical analyses were performed by Wilcoxon, Pearson chi-square, and Mann-Whitney-U tests at p < 0.05 level. Results: The SBS and WPO results were not statistically significant between the two groups. Significant differences were found between the groups in terms of fracture mode (p < 0.001). Greater percentages of the fractures showed mix type failure (85%) for Silorane and adhesive (60%) for Transbond-LR. Microleakage values were lower in low-shrinking composite than the control and this difference was found to be statistically significant (p < 0.001). Conclusions: Low-shrinking composite produced sufficient SBS, WPO and microleakage values on the etched enamel surfaces, when used as a lingual retainer composite.

• Journal of the Korean Wood Science and Technology
• /
• v.26 no.1
• /
• pp.97-105
• /
• 1998

This study examined the combined using effects of urea-formaldehyde (UF) resin and emulsifiable methylene diphyenyl diisocyanate (EMDI) resin to overcome performance limit of three-layer particleboards commonly made by UF resin. Two adhesive adding methods were applied with three types of resin combination system to each layer of particleboards. The one was simultaneously spreading method with emulsified compound resin (UF and EMDI) while the other was separately spreading method with unemulsified EMDI resin after UF resin spreading. The performance of particleboards bonded with 2% EMDI resin to the inner layers(IL) were similar to that of controls bonded with 8% UF resin. In the case of the emulsified compound resin application to the all layers of particleboards, there were marked reinforcing effects of EMDI resin, although a small amount of EMDI resin was mixed with UF resin. Especially bending MOR after 24 hours cold water-immersion and thickness swelling after 2 hours hot water-immersion of compound resin-bonded particleboards were remarkably different from those of pure UF resin-bonded particleboards. It was found that separately spreading method with unemulsified EMDI resin was more effective than simultaneously spreading method with emulsified compound resin to sustain the internal bond strength of particleboards after 24 hours cold water-immersion. In the resin combination systems to outer layers/inner layers of particleboards, water resistance and strength properties were superior in order of UF+EMDI/UF+EMDI > UF/UF+EMDI > UF/UF. And water resistance of particleboards was greatly dependent upon EMDI resin level in any adhesive adding method.

• The korean journal of orthodontics
• /
• v.48 no.3
• /
• pp.163-171
• /
• 2018

Objective: The aim of this study was to evaluate the mechanical and biological properties of orthodontic bonding agents containing silver- or zinc-doped bioactive glass (BAG) and determine the antibacterial and remineralization effects of these agents. Methods: BAG was synthesized using the alkali-mediated solgel method. Orthodontic bonding agents containing BAG were prepared by mixing BAG with flowable resin. $Transbond^{TM}$ XT (TXT) and $Charmfil^{TM}$ Flow (CF) were used as controls. Ion release, cytotoxicity, antibacterial properties, the shear bond strength, and the adhesive remnant index were evaluated. To assess the remineralization properties of BAG, micro-computed tomography was performed after pH cycling. Results: The BAG-containing bonding agents showed no noticeable cytotoxicity and suppressed bacterial growth. When these bonding agents were used, demineralization after pH cycling began approximately 200 to $300{\mu}m$ away from the bracket. On the other hand, when CF and TXT were used, all surfaces that were not covered by the adhesive were demineralized after pH cycling. Conclusions: Our findings suggest that orthodontic bonding agents containing silver- or zinc-doped BAG have stronger antibacterial and remineralization effects compared with conventional orthodontic adhesives; thus, they are suitable for use in orthodontic practice.

• Journal of Adhesion and Interface
• /
• v.22 no.4
• /
• pp.128-135
• /
• 2021

In this study, the acid polyols containing acid groups were synthesized, the novel polyurethane adhesive was developed by introducing the acid polyol by content. The acid polyols were introduced, the mechanical properties showed the maximum value when the acid content was 0.1 to 0.3 wt%, and it was confirmed that the mechanical properties and adhesive strength decreased at the content higher than 0.5 wt%. As the acid group, carboxylic acid and sulfuric acid were introduced to compare properties, and carboxylic acid showed stronger hydrogen bonding potential than sulfuric acid and improved mechanical properties. In addition, the correlation between particle size and mechanical properties was confirmed by introducing ZnO and CaCO₃. When ZnO and CaCO₃ were introduced, an ionic bond was formed with an acid group, and it was confirmed that mechanical properties were increased.

• Journal of the Korean Wood Science and Technology
• /
• v.51 no.5
• /
• pp.334-344
• /
• 2023

Dregs from the sugar palm (Arenga pinnata) starch industry are considered a waste product of the agricultural industry and have not yet been optimally utilized. Therefore, this study aimed to manufacture particleboards from dregs using different amounts of adhesive and particle size ratios. Sugar palm dregs, which had been separated into fibers and powder/fine particles, were used as raw material for making particleboards. The fiber had an average length of 6.84 ± 3.23 cm, while the fine particles were of a size that passed through size 10 mesh and remained in size 60 mesh. Three ratios of fiber to fine particles (100:0, 75:25, and 50:50 wt%) with three different amounts of sucrose-citric acid adhesive (10, 15, and 20 wt%) were used in this study. Increasing the amount of fine particles and the resin content can improve the physical properties and the internal bond strength of boards made from sugar palm dregs. The fine particles possibly filled the gap between the fibers in the particleboard, while the fibers exhibited a high bending strength. As a result, a high-performance particleboard can be attained by combining the composition ratio of fiber/fine particles and resin content. In this study, particleboards made from fiber/fine particles (75:25 wt%) and adhesive content of 15 wt% and 20 wt% had the mechanical properties that met the requirements of Japanese Industrial Standard (JIS) A 5908 type 18. Sugar palm dregs have the potential to be used as raw materials to create value-added particleboards.