• Journal of Adhesion and Interface
• /
• v.12 no.1
• /
• pp.26-33
• /
• 2011

Phosphoric acid treatments were conducted to improve the adhesion property of polyketone film to rubber. The effects of phosphoric acid treatments were characterized by using a contact angle analyzer and a XPS (X-ray photoelectron spectroscopy). Morphological changes were observed by using a scanning electron microscope (SEM) and an atomic force microscope (AFM) as the acid treatment condition varied in concentration and time. The contact angle was found to significantly decrease with the acid treatment. According to the XPS, increased wettability was attributed to the inclusion of oxygen containing groups such as hydroxyl, carbonyl and carboxyl by acid treatments. Cracks and pores were produced on the polyketone film surface and thus, roughness increased with the acid treatment. Interfacial adhesion strength between polyketone and natural rubber was largely improved by acid treatment due to the increased wettability and roughness of the polyketone surface. However, the higher level of acid treatment caused the degradation of the polyketone surface, and thus, its interfacial adhesion consequently decreased.

• The Journal of Advanced Prosthodontics
• /
• v.7 no.2
• /
• pp.108-114
• /
• 2015

PURPOSE. The aim of this study was to evaluate effect of different surface treatment methods on the bond strength between aged composite-resin core and luting agent. MATERIALS AND METHODS. Seventy-five resin composites and also seventy-five zirconia ceramic discs were prepared. 60 composite samples were exposed to thermal aging (10,000 cycles, 5 to $55^{\circ}C$) and different surface treatment. All specimens were separated into 5 groups (n=15): 1) Intact specimens 2) Thermal aging-air polishing 3) Thermal aging- Er:YAG laser irradiation 4) Thermal aging- acid etching 5) Thermal-aging. All specimens were bonded to the zirconia discs with resin cement and fixed to universal testing machine and bond strength testing loaded to failure with a crosshead speed of 0.5 mm/min. The fractured surface was classified as adhesive failure, cohesive failure and adhesive-cohesive failure. The bond strength data was statistically compared by the Kruskal-Wallis method complemented by the Bonferroni correction Mann-Whitney U test. The probability level for statistical significance was set at ${\alpha}$=.05. RESULTS. Thermal aging and different surface treatment methods have significant effect on the bond strength between composite-resin cores and luting-agent (P<.05). The mean baseline bond strength values ranged between $7.07{\pm}2.11$ and $26.05{\pm}6.53$ N. The highest bond strength of $26.05{\pm}6.53$ N was obtained with Group 3. Group 5 showed the lowest value of bond strength. CONCLUSION. Appropriate surface treatment method should be applied to aged composite resin cores or aged-composites restorations should be replaced for the optimal bond strength and the clinical success.

• The Journal of Korean Academy of Prosthodontics
• /
• v.36 no.1
• /
• pp.26-49
• /
• 1998

The purpose of this study was to confirm the formation of hybrid layer and resin tags in dentin tissue and the possibility of bonding between luting cements used for the prosthesis and the resinous surface coated with resin bonding agents to prevent the dentin hypersensitivity after abutment preparation. Some resin bonding agents, which may have the possibility of bonding with polyacrylic acid as a liquid ingredient of polycarboxylate and glass ionomer cements, were selected. All-Blond desensitizer containing NTG-GMA and BPDM, Scotch-Bond Multipurpose plus containing HEMA, and XR-bond containing organophosphate were selected as a coating agent. Dental cements were zinc phosphate, polycarboxylate, and glass ionomer cement. After the exposed dentin surface of premolars was ethced with 10% phosphoric acid and coated with resin bonding agents, the morphology of treated surfaces and the resin tags and hybrid layers on sectioned surfaces were observed by SEM. Shear bond strength between the resin bonding agents and 3 kinds of cements was measured 24 hours after bonding. On the debonded surfaces of the shear bond strength tested specimens, the cement tags and the bonding sites between the resin materials and cements were examined by SEM. Following conclusions were drawn : 1. Coating of dentin with resin bonding agents had no effect on the shear bond strength of zinc phosphate cement. 2. Both of polycarboxylate and glass ionomer cements showed the increased shear bond strength by the dentinal coating with Scotch-Bond Multipurpose plus containing HEMA. However, in the case of dentinal coating with some agents containing NTG-GMA and BPDM or organophosphate, polycarboxylate cement exhibited the lowered shear bond strength, and glass ionomer cement showed the unchanged shear bond strength. 3. Complete obstructions of dentinal tubules were observed on the dentin coated with All-Bond desensitizer or XR-bond, but distinct shape of the orifices of dentinal tubules was observed consistently on the dentin coated with Scotch-Bond Multipurpose plus. 4. The hybrid layer was thickest on the dentin coated with All-Bond desensitizer, and the length of resin tags was longest on the dentin coated with Scotch-Bond Multipurpose plus. 3. On the debonded specimens which had been bonded with polycarboxylate cement or glass ionomer cement after coating with Scotch-Bond Multipurpose plus, the cement tags and the bonding sites between the resinous surface and the cements could be examined.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.41 no.2
• /
• pp.125-133
• /
• 2014

The purpose of this study was to investigate the effect of various surface treatment methods on the shear bond strength of orthodontic brackets in vitro. Ninety six specimens, 6 mm in diameter and 5 mm in height, were made with composite resin ($Filtek^{TM}$ Z350 XT, 3M ESPE, USA) and treated with an aging procedure. After aging, the specimens were randomly separated in six groups: (1) control with no surface treatment, (2) 37% phosphoric acid gel, (3) 4% hydrofluoric acid gel, (4) sodium bicarbonate particle abrasion, (5) diamond bur, and (6) 1 W carbon dioxide laser for 5s. The metal brackets were bonded to composite surfaces by means of an orthodontic adhesive (Transbond XT, 3M Unitek, USA). Shear bond strength values were evaluated with a universal testing machine (R&B Inc., Korea). Analysis of variance showed a significant difference between the groups. Group 5 had the highest mean shear bond strength (11.9 MPa), followed by group 6 (11.1 MPa). Among the experimental groups, group 2 resulted in the weakest mean shear bond strength (5.22 MPa). The results of this study suggest that the repair shear bond strength of the aged composite resin was acceptable by surface treatment with a carbon dioxide laser.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.48 no.4
• /
• pp.460-466
• /
• 2021

The purpose of this study was to compare the effect of the hemostatic agent containing aluminum chloride with hemostatic agent containing ferric sulfate on the shear bond strength of resin-modified glass ionomer cement(RMGIC) to dentin in primary tooth. Twenty extracted non-carious human primary teeth were collected in this study. The specimens were cut to expose dentin and polished. The specimens were randomly seperated into 3 groups for treatment; group I: polyacrylic acid(PAA), RMGIC; group II: aluminum chloride, PAA, RMGIC; group III: ferric sulfate, PAA, RMGIC Ten specimens from each group were subjected to shear bond strength test. The mean shear bond strength of each group was as follows: 10.07 ± 1.83 MPa in Group I, 7.62 ± 0.78 MPA in group II, 5.23 ± 0.78 MPa in group III. There were significant differences among all groups(p < 0.001). In conclusion, both aluminum chloride hemostatic agent and ferric sulfate hemostatic agent decreased the shear bond strength of RMGIC to dentin. And ferric sulfate hemostatic agent decreased the shear bond strength of RMGIC more than the aluminium chloride hemostatic agent.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2002.10a
• /
• pp.11-16
• /
• 2002

The production of Portland cement involves maximum use of resources and energy, which leads to destruction of tile ecological environment, raising in serious environmental issues such as acid rain and the greenhouse effect. In order to combat the arising problems associated with Portland cement, it thus is necessary that a non-clinker cement should be developed. In this study, non-clinker cement is produced by blending granulate blast furnace slag with phosphogypsum as main materials, and small amounts of hydrate lime or waste lime as activators. This paper aims to investigate compressive strength according to various condition of mixing ratio, blame, W/C ratio and curing temperature. Compressive strength of non-clinker cement increases continuously according to increase in curing age and blain. Although the compressive strength is fairly comparable to that of OPC in the early curing age, it reaches a higher lever in the later age than that of OPC due to the optimum mixing ratio and the continuous reaction of slag and phosphogypsum. Results obtained from this study have shown that non-clinker cement could be used as a replacement of OPC.

• The Korean Journal of Ceramics
• /
• v.3 no.2
• /
• pp.105-109
• /
• 1997

The effects of surface conditions of the C-2 cemented carbide substrate on the adhesion of diamond film were investigated. The substrates were pretreated for different times with Murakami's reagent and then the acid solution of an H2SO4-H2O2. The adhesion strength was estimated by a peeling area around the Rockwell-A indentation. The cutting performance of the diamond-coated tools was evaluated by measuring flank wears in dry turning of Al-17% Si alloy. The morphology of deposited diamond crystallites was dominated by (111) and (220) surfaces with a cubooctahedral shape. The diamond film quality was hardly affected by the surface conditions of the substrate. The variation of tool life with longer substrate etching times resulted from a compromies between the increase of film adhesion at the interface and the decrease of toughness at the substrate surface. The coated tools were mainly deteriorated by chipping and flaking of the diamond film form a lock of adhesion strength, differently from the wear phenomena of PCD tools.

• Journal of the Korean Ceramic Society
• /
• v.31 no.9
• /
• pp.941-948
• /
• 1994

An underwater grout on material resistance against segregation in water were studied by water soluble polymer (methyl cellulose and acrylic acid ester and styrene). The mechanical properties of the grout agents were investigated through the observation of the microstructure and application of fracture mechanic. When the soluble polymer MC+AAES added with 0.6 wt% to the underwater grout agents the compressive strength, flexural strength and Young's modulus were about 58 MPa, 10 MPa and 3.2 GPa respectively, and critical stress intensity was about 0.8 MNm-1.5. It can be considered that the strength improvement and fracture toughness increase may be due to the pore decrease and bonding force by material resistance against segregation in water.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07a
• /
• pp.406-409
• /
• 2002

The primary insulation system used in an oil-filled transformer is Kraft paper, wood, porcelain and, of course, oil. Modern transformers use paper that is chemically treated to improve its tensile strength properties and resistance to aging caused by immersion in oil. These insulation papers are mainly aged to thermal stress. Over the course of the insulation paper and oil's life it is exposed to high temperatures, oxygen and water. Its interaction with the steel of the tank and core plus the copper and aluminium of the windings will eventually cause the chemical properties of the oil to decay. High temperature have an effect on mechanical strength of cellulous paper using the layer insulation. We made two aging cell in which thermal aging tests of insulation papers and mineral oil are conducted. It is measured dielectric strength, number of acid, moisture, etc. of insulation paper and oil aged in the aging cells.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.05a
• /
• pp.731-736
• /
• 2003

Alkali silicate system has wide application to accelerating admixture for shotcrete, but it has several problems that decrease long-term strength and delay setting time. So alkali-free system was gradually focused on accelerating admixtures for shotcrete due to its environmental property. The aim of this study is to investigate effect of alkali-free accelerating admixtures on aluminum sulfate system containing diethanolamine or acrylic acid etc. The alkali-free accelerating admixture has better properties than silicate system accelerating admixtures on compressive strength and low pH as shotcrete. Especially, the compressive strength of alkali-free accelerating admixture containing diethanolamine was increased about 10% compared with the value of ordinary portland cement.