• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.3
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• pp.84-89
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• 2003

The joint method and characteristics of lubricant Impregnated MC nylon and metal are analyzed. Considering the productivity and economics, two materials are Joined with the process of turning, knurling, and induction heating. The Joint strength is determined by adhesion of the melted nylon, the size of knurl, and the interference from the difference of the diameters. The parameters affecting induction heating process are analyzed. The adhesion strength of the melted nylon is measured. Finally the joint strength is analyzed in the environments of low, room, and high temperature. The nylon/metal Joined material is expected to be widely used as the sliding machine elements with good friction and shear strength.

• Journal of the Korean Wood Science and Technology
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• v.49 no.3
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• pp.274-282
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• 2021

Transparent and colorless melamine-urea-formaldehyde (MUF) resins make it difficult to identify the area of wood failure percentage (WFP) in the fracture surface of bonded wood specimens. Therefore, in this study, we develop a method of measuring WFP after the adhesion strength measurement of MUF resins under shear stress. The fractured wood surface of b lock shear strength (BSS) specimens bonded with cold-setting MUF resins at three melamine contents (20%, 30%, and 40%) was marked black, and then, WFP was accurately measured via image analysis. WFP values measured using this method consistently increased with BSS as the melamine content increased, showing the reliability of this new method. The results suggested that this new method is useful and reliable for measuring the WFP of the fracture surface of wood specimens bonded with colorless adhesives such as urea-formaldehyde, MUF, and melamine-formaldehyde resins.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.143-146
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• 2002

Unsized AS-4 carbon fibers were etched by RF plasma and then coated via plasma polymerization in order to enhance adhesion to vinyl ester resin. The gases utilized for the plasma etching were Ar, $N_2 and O_2$, while the monomers used for the plasma polymerization coating were acetylene, butadiene and acrylonitrile. The conditions for the plasma etching and the plasma polymerization were optimized by measuring interfacial adhesion with vinyl ester resin via micro-droplet tests. Among the treatment conditions, the combination of Ar plasma etching and acetylene plasma polymerization provided greatly improved interfacial shear strength (IFSS) of 69MPa compared to 43MPa with as-received carbon fiber. Based on the SEM analysis of failure surface and load-displacement curve, it was assume that the failure might be occurred at the carbon fiber and plasma polymer coating. The plasma etched and plasma polymer coated carbon fibers were subjected to analysis with SEM, XPS, FT-IR or Alpha-Step, and dynamic contact angles and tensile strengths were also evaluated. Plasma polymer coatings did not change tensile strength and surface roughness of fibers, but decreased water contact angle except butadiene plasma polymer coating, possibly owing to the functional groups introduced, as evidenced by FT-IR and XPS.

• The Journal of Advanced Prosthodontics
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• v.12 no.2
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• pp.75-82
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• 2020

PURPOSE. The aim of this study was to investigate the shear bond strength of luting cements used with implant retained restorations on to titanium specimens after different surface treatments. MATERIALS AND METHODS. One hundred twenty disc shaped specimens were used. They were divided into three groups considering the surface treatments (no treatment, sandblasting, and oxygen plasma treatment). Water contact angle of specimens were determined. The specimens were further divided into four subgroups (n=10) according to applied cement types: polycarboxylate cement (Adhesor Carbofine-AC), temporary zinc oxide free cement (Temporary CementZOC), non eugenol provisional cement for implant retained prosthesis (Premier Implant Cement-PI), and non eugenol acrylic-urethane polymer based provisional cement for implant luting (Cem Implant Cement-CI). Shear bond strength values were evaluated. Two-way ANOVA test and Regression analysis were used to statistical analyze the results. RESULTS. Overall shear bond strength values of luting cements defined in sandblasting groups were considerably higher than other surfaces (P<.05). The cements can be ranked as AC > CI > PI > ZOC according to shear bond strength values for all surface treatment groups (P<.05). Water contact angles of surface treatments (control, sandblasting, and plasma treatment group) were 76.17° ± 3.99, 110.45° ± 1.41, and 73.80° ± 4.79, respectively. Regression analysis revealed that correlation between the contact angle of different surfaces and shear bond strength was not strong (P>.05). CONCLUSION. The retentive strength findings of all luting cements were higher in sandblasting and oxygen plasma groups than in control groups. Oxygen plasma treatment can improve the adhesion ability of titanium surfaces without any mechanical damage to titanium structure.

• Composites Research
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• v.34 no.2
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• pp.82-87
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• 2021

The mechanical properties of carbon fiber-reinforced epoxy composites (CFRPs) are greatly dependent on the interfacial adhesion between the carbon fibers and the epoxy matrix. Introducing nanomaterial reinforcements into the interface is an effective approach to enhance the interfacial adhesion of CFRPs. The main purpose of this work was to introduce graphitic nanofiber (GNFs) between an epoxy matrix and carbon fibers to enhance interfacial properties. The composites were reinforced with various concentrations of GNFs. For all of the fabricated composites, the optimum GNF content was found to be 0.6 wt%, which enhanced the interlaminar shear strength (ILSS) and fracture toughness (KIC) by 101.9% and 33.2%, respectively, compared with those of neat composites. In particular, we observed a direct linear relationship between ILSS and KIC through surface free energy. The related reinforcing mechanisms were also analyzed and the enhancements in mechanical properties are mainly attributed to the interfacial interlocking effect. Such an effort could accelerate the conversion of composites into high performance materials and provide fundamental understanding toward realizing the theoretical limits of interfacial adhesion and mechanical properties.

• The korean journal of orthodontics
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• v.49 no.6
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• pp.404-412
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• 2019

Objective: To assess shear bond strength and failure mode (Adhesive Remnant Index, ARI) of orthodontic brackets bonded to polymethylmethacrylate (PMMA) blocks for computer-aided design/manufacture (CAD/CAM) fabrication of temporary restorations, following substrate chemical or mechanical treatment. Methods: Two types of PMMA blocks were tested: $CAD-Temp^{(R)}$ (VITA) and $Telio^{(R)}$ CAD (Ivoclar-Vivadent). The substrate was roughened with 320-grit sandpaper, simulating a fine-grit diamond bur. Two universal adhesives, Scotchbond Universal Adhesive (SU) and Assure Plus (AP), and a conventional adhesive, Transbond XT Primer (XTP; control), were used in combination with Transbond XT Paste to bond the brackets. Six experimental groups were formed: (1) $CAD-Temp^{(R)}/SU$; (2) $CAD-Temp^{(R)}/AP$; (3) $CAD-Temp^{(R)}/XTP$; (4) $Telio^{(R)}$ CAD/SU; (5) $Telio^{(R)}$ CAD/AP; (6) $Telio^{(R)}$ CAD/XTP. Shear bond strength and ARI were assessed. On 1 extra block for each PMMA-based material surfaces were roughened with 180-grit sandpaper, simulating a normal/medium-grit ($100{\mu}m$) diamond bur, and brackets were bonded. Shear bond strengths and ARI scores were compared with those of groups 3, 6. Results: On $CAD-Temp^{(R)}$ significantly higher bracket bond strengths than on $Telio^{(R)}$ CAD were recorded. With XTP significantly lower levels of adhesion were reached than using SU or AP. Roughening with a coarser bur resulted in a significant increase in adhesion. Conclusions: Bracket bonding to CAD/CAM PMMA can be promoted by grinding the substrate with a normal/medium-grit bur or by coating the intact surface with universal adhesives. With appropriate pretreatments, bracket adhesion to CAD/CAM PMMA temporary restorations can be enhanced to clinically satisfactory levels.

• Journal of Technologic Dentistry
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• v.30 no.2
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• pp.23-29
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• 2008

The purpose of this study is to evaluate possibility of using indirect composite resin instead of porcelain through the measurement of shear bond strength between zirconia core and indirect composite resin under treatment of $Rocatec^{TM}$ system for improving the adhesion of indirect composite resin. 20 cylindrical zirconia core specimens were divided into 2 groups, according to zirconia surface treatment and attached materials: 1) treated with sandblast and attached with indirect composite resin, 2) treated with sandblast + $Rocatec^{TM}$ system and attached with indirect composite resin. The shear bond strength of each experimental group was measured by MTS and the changes of zirconia core surface according to surface treatments were obtained by SEM observation and measurements of surface roughness. The mean shear bond strength values are $0.55\;{\pm}\;0.11MPa$(Group SC) and $1.16\;{\pm}\;0.46MPa$(Group SRC). The mean Ra values for the surface treatments were follows: $0.39\;{\pm}\;0.13$($100{\beta}_{{\mu}m}$ sandblast) and $0.50\;{\pm}\;0.03$($100{\beta}_{{\mu}m}$ sandblast + $Rocatec^{TM}$ system). In the analysis of EDS, Si element was detected in the Group SC. The shear bond strength between zirconia core and indirect composite resin was improved significantly by using $Rocatec^{TM}$ system.

• Journal of Adhesion and Interface
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• v.23 no.4
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• pp.122-129
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• 2022

In this study, the hydrophilicity of the metal fiber is improved by introducing an oxygen-containing functional group to the fiber surface after treatment of the metal fiber using the oxygen plasma treatment time as an experimental variable. For the surface modification of metal fibers, changes in surface properties before and after plasma treatment were observed using SEM and x-ray photoelectron spectroscopy (XPS). In order to observe the effect of the plasma treatment time on the surface of the metal fiber, the change in contact angle of the metal fiber with respect to a polar solvent and a non-polar solvent was measured. After calculating the change in surface free energy using the measured contact angle, the contact angle and the surface free energy for metal fibers before and after oxygen plasma treatment were compared, and the correlation with the adhesion work was also considered. The microdroplet specimens were prepared to investigate the effect of surface changes of these metal fibers on the improvement of shear strength at the interface when combined with other materials and the interfacial shear strength was measured, and the correlation with the adhesion work was also identified. Therefore, the oxygen plasma treatment of the metal fiber results in an increase in the physical surface area on the fiber surface and a change in contact angle and surface energy according to the introduction of the oxygen-containing functional group on the surface. This surface hydrophilization resulted in improving the interfacial shear strength with the polymer resin.

• Journal of Adhesion and Interface
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• v.16 no.1
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• pp.29-34
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• 2015

Hydrocarbon resins, which are defined as low molecular weight, amorphous, and thermoplastic polymers, are widely used as tackifier for various types of adhesives, as processing aids in rubber compounds, and as modifiers for plastics polymers such as isotactic polypropylene. Typically, hydrocarbon resins are non-polar, and thus highly compatible with non-polar rubbers and polymer. However, they are poorly compatible with polar system, such as acrylic copolymer, polyurethanes, and polyamides. Moreover, recently the raw materials of hydrocarbon resin from naphtha cracking had been decreased because of light feed cracking such as gas cracking. To overcome this problem, in this study, novel hydrocarbon resins were designed to have a highly polar chemical structure which material is sustainable. And, it was successfully synthesized by Diels-Alder reaction of dicyclopentadiene monomer and sorbic acid from blueberry as renewable resources. Acrylic resins were formulated with various tackifiers solution including sorbic acid grafted hydrogenated dicyclopentadiene hydrocarbon resins in acrylic adhesive and rolling ball tack, loop tack, $180^{\circ}$ peel adhesion strength, and shear adhesion strength were measured. The properties depend on the softening point and polar content of tackifiers.

• Korean Journal of Materials Research
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• v.9 no.7
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• pp.724-734
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• 1999

The adhesion characteristics of the thermoplastic resins such as PE, PP PVC, PET and PS were investigated on the surfaces of conventional steel (SS41), steel (SS41P) treated with ultrasonic waves and the SS41P coated with several ceramic powders (SS41PC) by the plasma spray. Alumina (Al$_2$O$_3$), alumina titania (Al$_2$O$_3$95%, TiO$_2$ 5%) and zirconia yttria (ZrO$_2$ 95%, $Y_2$O$_3$5% ) were used for the materials plasma spray The morphologies, surface hardness, surface roughness, and contact angles on SS41, SS41P, and SS41PC were examined. The tensile shear strength and peel strength of the polymers which were attached to the surfaces of ceramics coated on SS41P also were measured. The tensile shear strength and peel strength of polymers adhered to ceramic surface coated on steel were found to be stronger than those of conventional steel. The tensile shear strength and peel strength of the polymers adhered on the surfaces of ceramics coated steel increased in the following order PE > PET > PP > PS > PVC. The high adhesion strength of PE may be attributed to the surface roughness and its anchor effect on the ceramic surface.