• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1224-1229
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• 2018

In this study, 2-hedroxyethyl methacrylate (2-HEMA) was graft synthesized on water-dispersed polyurethane using polytetramethylene ether glycoll (PTMG), and then the film of resin was prepared and the physical properties of polyurethane resin were measured. The mechanical properties of the synthesized polyurethane resin were measured by using FT-IR, UTM, adhesion performance measuring instrument. As a result of tensile strength measurement, the tensile strength of HPUD4 with high 2-HEMA content was increased to $5.05kgf/mm^2$, the elongation was measured as 285% of the HPUD1 sample not containing 2-HEMA and adhesive strength of HPUD4 sample was measured at 9.1 sec to 635 psi.

• Journal of Adhesion and Interface
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• v.5 no.2
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• pp.22-36
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• 2004

Several in-situ testing methods of adhesively bonded joints under static short-time tensile loading are critically analyzed in terms of experimental procedure and data evaluation. Due to its rather homogeneous stress state across the glue line, the tensile-shear test with thick single-lap specimens, according to ISO 11003-2, has become the most important test process for the determination of realistic materials parameters. This basic method, which was improved in both, the experimental part by stepped adherends and easily attachable extensometers and the evaluation procedure by numeric substrate deformation correction and test simulation based on the finite element method (FEM), is therefore demonstrated by application to several kinds of adhesives and metallic adherends. Multi-axial load decreases the strength of a joint. This effect, which is illustrated by an experimental comparison, impedes the derivation of realistic mechanical characteristics from measured force-displacement curves. It is shown by numeric modeling that tensile-shear tests with thin plate substrates according to ISO 4587, which are widely used for quick industrial quality assurance, reveal an inhomogeneous stress state, especially because of relatively large adherend deformation. Complete experimental determination of the elastic properties of bonded joints requires independent measurement of at least two characteristics. As the thick-adherend tensile-shear test directly yields the shear modulus, the tensile butt-joint test according to ISO 6922 represents the most obvious complement of the test programme. Thus, validity of analytical correction formulae proposed in literature for the derivation of realistic materials characteristics is verified by numeric simulation. Moreover, the influence of the substrate deformation is examined and a FEM correction method introduced.

• Korean Journal of Veterinary Research
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• v.43 no.4
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• pp.703-708
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• 2003

This study was carried out to compare the efficacy of carboxymethyl chitosan fabric (CMCF) with that of the combination of low molecular weight heparin (LMWH) and CMCF for the prevention of postoperative adhesions in the rat. Adhesions were induced by suturing both the ileal serosa and peritoneum scraped until petechial bleeding occurred. CMCF were sutured between two surfaces, and LMWH were instilled intraperitoneally immediately before closure of the peritoneomuscular layer. The adhesions were blindly assessed 2 weeks later by using a tensiometer. The mean tensile strength(Newton) of formed adhesions was $2.59{\pm}0.85$ in control group, $2.10{\pm}0.75$ in the CMCF group and $1.53{\pm}0.44$ in the CMCF+LMWH group. The most favorable prevention against adhesion was achieved in the CMCF+LMWH group. Therefore, we could conclude that CMCF+LMWH were effective in prevention against postoperative adhesion in the rat.

• Journal of Veterinary Clinics
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• v.24 no.3
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• pp.379-383
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• 2007

This study was performed to compare the effects of carboxymethylcellulose (CMCE), chondroitin sulfate (Chondron), and carboxymethylchitosan (CMCH) on preventing intraperitoneal adhesion. As a result, the tensile strength of adhesions formed between the parietal peritoneum and the ileal serosa was significantly decreased in the groups of three different kinds of anti-adhesive agents. The distance of adhesion site was slightly increased in the treatment groups comparing control group. In the CMCH group, the inflammatory cell infiltration, collagen hyperplasia, and neovascularization were significantly lower than those of control group. It was observed that the damage at intestinal serosa was significantly decreased in the chondron and CMCH groups comparing control group. Therefore CMCH may be useful as a anti-adhesive agent in the prevention of intraperitoneal adhesion in rats.

• Journal of Adhesion and Interface
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• v.16 no.1
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• pp.22-28
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• 2015

In this study, Waterborne polyurethanes (WPU) using Epoxy group were synthesized with polyester polyol, epoxy resin, 4,4-dicyclohexylmethane diisocyanate ($H_{12}MDI$), dimethylol propionic acid (DMPA) to improve the hydrolysis resistance and adhesion. In addition, the properties of the synthesized waterborne polyurethane was evaluated through DSC, UTM, adhesion strength. Tg of the synthesized waterborne polyurethane is shown in the vicinity of $-50^{\circ}C$. Tg were increased with as epoxy resin contents increased. The tensile strength was increased as the content of epoxy resin increases, elongation was decreased. Optimum adhesion and hydrolysis-resistance strength were obtained when polyol : epoxy ratio was 99 : 1.

• Journal of Adhesion and Interface
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• v.13 no.3
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• pp.116-120
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• 2012

In this study, waterborne polyurethane was prepared from polyester polyol, $H_{12}MDI$, DMPA and sulfopropylated polypropyleneglycol-${\alpha}$,${\omega}$-diamine (SP). The $T_g$ of waterborne polyurethane was increased as the SP content increased, while it was decreased at the NCO/OH ratio of 1.8. Also the hydrolysis-resistance and tensile strength were increased as the SP content increased. The tensile strength decrement of WPU-SP was 2~5% with the exception of WPU-SP-1.

• Journal of the Korean Wood Science and Technology
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• v.47 no.2
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• pp.221-228
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• 2019

This study reports the performance of urea-formaldehyde (UF) resins prepared at two different low formaldehyde/urea (F/U) mole ratios with different numbers of urea addition during synthesis. The second or third urea was added during the synthesis of UF resins to obtain two different low molar ratios of 0.7 and 1.0, respectively. The molecular weights, cure kinetics, and adhesion performance of these resins were characterized by the gel permeation chromatography, differential scanning calorimetry, and tensile shear strength of plywood, respectively. When the number of urea additions and F/U molar ratio increased, the gelation time decreased, whereas the viscosity and molecular weight increased. Further, the UF resins prepared with the second urea and 1.0 molar ratio resulted in greater activation energy than those with third urea and 0.7 molar ratio. Tensile shear strength and formaldehyde emission (FE) of the plywood that bonded with these resins increased when the number of urea additions and molar ratio increased. These results suggest that the UF resins prepared with 0.7 molar ratio and third urea addition provide lower adhesion performance and FE than those resins with 1.0 mole ratio and the second urea addition.

• Journal of the Korean Applied Science and Technology
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• v.33 no.1
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• pp.168-175
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• 2016

The surface of glass fiber bundle was modified with functionalized silanes and phenolic resin to improve the tensile strength as well as the adhesion of glass fiber to matrix phenolic resin. The surface modification of reinforcing glass fiber can play a significant role in controlling whole composite characteristics. We applied surface modification of glass fiber with two different functionalized silanes, such as glycidyltrimethoxysilane(G-silane) and aminopropyltriethoxysilane (A-silane), and phenol formaldehyde(PF) resin in one pot or separated process under different coating compositions and temperatures. Thermal treatment temperature is very important factor to improve the mechanical properties of modified glass fiber. Modified glass fiber bundle treated at $170^{\circ}C$ showed the highest tensile strength of $10.05g_f/D$. Surface analyses by scanning electron microscope(SEM) and FT-IR spectroscopy were used to characterize the surface coatings on glass fiber bundles. Mechanical property changes as functions of treatment conditions and coupling agent types were also explained.

• Journal of Dental Rehabilitation and Applied Science
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• v.16 no.3
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• pp.211-220
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• 2000

The use of autopolymerizing-cured resin and light-cured resin for direct relining of complete and partial dentures has been popular. This investigation compared the adhesion of autopolymerizing-cured reline resin(Tokuso Rebase, Mild Rebaron) or light-cured reline resin(Mild Rebaron LC, Lighton-U) to metal base or resin base. Cylindrical samples were made from metal($Biosil^{(R)}$) or heat-cured resin(QC-20) and were prepared to produce a flat bonding surface. Cylindrical metal samples were roughened by scratch or by scratch and sandblast and were treated with primer(MR Bond) after scratch and sandblast. And then, liners were prossesed to the cylindrical metal or resin samples according to the manufacturer's recommendations so as to bond metal base or resin base. The specimens were tested in pure tension by using an Instron Univesal testing machine for the four direct reline resins. The results were as follows ; 1. In comparison with tensile bond strength of material relined on resin base or metal base, the case of resin base produced significantly higher tensile bond strength than the case of metal base. 2. Metal surface pretreatment or primer improved the tensile bond strength between the reline resin and the metal($Biosil^{(R)}$) base. 3. The tensile bond strength of Mild Rebaron LC relined on resin base or metal base were similar to those of the other reline resins.

• Tribology and Lubricants
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• v.37 no.3
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• pp.83-90
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• 2021

In this study, an ultrasonic nanocrystal surface modification (UNSM) was used to improve the mechanical properties, scratch resistance and tribological performance of Cu-based bimetals, which are usually used to manufacture sliding bearings and bushings for internal combustion engines (ICEs). Two different Cu-based bimetals, namely CuPb10Sn10 and CuSn10Bi7, were sintered onto a low carbon steel substrate. The mechanical properties and dry tribological performance using a tensile tester and micro-tribo tester were evaluated, respectively. The scratch resistance was assessed using a micro-scratch tester at an incremental load. The tensile test results showed that the yield strength (YS) and ultimate tensile strength (UTS) of both Cu-based bimetals increased after UNSM. Furthermore, the scratch and tribological tests results revealed that the scratch resistance and tribological performance of both Cu-based bimetals were improved by the application of UNSM. These improvements were mainly attributed to the eliminated pores, increased hardness and reduced roughness after UNSM. CuSn10Bi7 demonstrated better mechanical properties, scratch resistance and tribological performance than CuPb10Sn10. It was found that the presence of Bi in CuSn10Bi7 formed a Cu₁₁Bi₇ intermetallic phase, which is harder than Cu₃Sn. Hence, CuSn10Bi7 demonstrated higher strength and wear resistance than CuPb10Sn10. In addition, a CuSn10Bi7 formed both SnO₂ and Bi₂O₃ that prevented adhesion and improved the tribological performance. It can be expected that under dry tribological conditions, ICEs can utilize UNSM bearings and bushings made of CuSn10Bi7 instead of CuPb10Sn10 under oil-lubricated conditions.