• Journal of Welding and Joining
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• v.16 no.2
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• pp.48-56
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• 1998

This study was performed to find the best bonding conditions by comparing mechanical properties in thermoplastic resin of polyethylene (PE) and polyamide (PA) adhesion. Following results were obtained from the tests with varying welding time and welding pressure. Satisfactory adhesion was executed in ultrasonic welding for the same materials of PE and PA. The best welding conditions were found to be welding time of 1 second, welding pressure of 250kPa for PE-PE weding, 2 second and 350kPa for PA-PA welding. Welding time and welding pressure end to increase with the increase of materials strength. Dissimilar materials were adhered when adhesion and ultrasonc welding were performed simultaneously. The observation of the structure of ultrasonic welding area with microscope showed differenticated structures between well adhered region and badly adhered region.

• Macromolecular Research
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• v.16 no.7
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• pp.596-603
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• 2008

To improve the mechanical properties, dimensional stability and blood compatibility, the biomedical material $Pellethene^{(R)}$ was blended with multiblock polyurethane (MPU) containing phospopholipid/long alkyl chain (C-18) at the various MPU contents and crosslinked using dicumyl peroxide as a crosslinking agent. The maximum MPU content for stable $Pellethene^{(R)}$/MPU blended films was approximately 30 wt%. The optimum crosslinking agent content and crosslinking time with respect to the mechanical properties were 4 wt% and 3 h, respectively. The mechanical properties (tensile strength and elongation at break) and water absorption of the crosslinked blend film increased with increasing MPU content. The test of platelet adhesion on the surfaces of the crosslinked blend film showed a decrease in the level of platelet adhesion from 70% to 6% with increasing MPU content from 0 to 30 wt%. These results suggest that the crosslinked $Pellethene^{(R)}$/MPU-30 (MPU content: 30 wt%) sample has strong potential as a novel material for blood compatible material applications.

• Archives of Plastic Surgery
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• v.36 no.5
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• pp.543-547
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• 2009

Purpose: Adhesion is the most common and troublesome complication after repair of flexor tendon injury. Recently, use of sodium hyaluronate derivatives for adhesion prevention is increasing. A commercial product, Guardix$^{(R)}$, sodium hyaluronate(NaHe) combined with carboxymethylcellulose(CMC) has been newly developed as a preventive material for adhesion. We have investigated its effect in rabbits. Methods: Twenty seven male New Zealand white rabbits were operated under ketamine anesthesia. After tendon repair in zone II of the hind paw, Guardix$^{(R)}$(experimental group) or normal saline(control group) was administered. Biomechanical tests were performed to estimate adhesion formation at 2, 4, 8, and 12 weeks after the operation. Maximum tensile load to flex the distal interphalangeal joint 50 degree from its resting state(MTL50) was measured, depicting the amount of adhesion formed. Subsequently, breaking strength was assessed. Results: There were no postoperative complications such as infection, wound dehiscence, or hematoma. MTL50 was significantly lower in the experimental group than in the control group at 4, 8, 12 weeks (p<0.05). Mean value of MTL50 was 6.64N in the experimental group and 28.53N in the control group at 12 weeks after surgery. There were no significant differences in breaking strength. Conclusion: Our results indicate that Guardix$^{(R)}$ is helpful in reducing adhesion formation and does not interfere with normal healing processes of the tendon.

• Fibers and Polymers
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• v.7 no.4
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• pp.372-379
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• 2006

The surface topography, tensile properties, and thermal properties of ramie fibers were investigated as reinforcement for fully biodegradable and environmental-friendly 'green' composites. SEM micrographs of a longitudinal and cross sectional view of a single ramie fiber showed a fibrillar structure and rough surface with irregular cross-section, which is considered to provide good interfacial adhesion with polymer resin in composites. An average tensile strength, Young's modulus, and fracture strain of ramie fibers were measured to be 627 MPa, 31.8 GPa, and 2.7 %, respectively. The specific tensile properties of the ramie fiber calculated per unit density were found to be comparable to those of E-glass fibers. Ramie fibers exhibited good thermal stability after aging up to $160^{\circ}C$ with no decrease in tensile strength or Young's modulus. However, at temperatures higher than $160^{\circ}C$ the tensile strength decreased significantly and its fracture behavior was also affected. The moisture content of the ramie fiber was 9.9 %. These properties make ramie fibers suitable as reinforcement for 'green' composites. Also, the green composites can be fabricated at temperatures up to $160^{\circ}C$ without reducing the fiber properties.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.6
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• pp.560-567
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• 2009

This paper was designed to estimate the adhesion strength of galvannealed coatings on steel sheets. The adhesion strength were evaluated using single lap - shear tests where the lap joint was bonded by structural adhesive. Tests were performed for overlap length of 5mm, 10mm and 15 mm and three directions (0, 45, 90) of steel sheets used as the adherend of the overlap joint. After the tests, FE simulations of the single lap-shear test were also carried out to observe the stress distribution in the interface between the adhesive and the coated sheet. The results showed that the joint failure loads obtained from the tensile tests of bonded single lap-joints were the same, regardless of overlap lengths and directions of steel sheets. Also, the failure of galvannealed coatings greatly depended on shear stress distribution in the interface and the value was about 30MPa.

• Journal of the Korean Wood Science and Technology
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• v.41 no.2
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• pp.134-140
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• 2013

UV curing was introduced via a chemical treatment by adding small amounts of a hexafunctional acrylic monomer and a photoinitiator to improve the mechanical properties of PLA. This study also employed a semi-interpenetrated structured polymer network through the process of UV-curing. The UV curing behaviors were investigated using FTIR-ATR spectroscopy and gel fraction determination. Also, the tensile strength was investigated with different hexafunctional acrylic monomer contents and UV doses. The results showed that the crosslinking of UV-induced chemically treated PLA started at a low content of hexafunctional acrylic monomer, resulting in a significant improvement of the mechanical properties compared to those of neat PLA due to crosslinking.

• Journal of Adhesion and Interface
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• v.8 no.4
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• pp.8-13
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• 2007

In this study, solvent-free waterborne polyurethanes (SWPU) were synthesized with teramethylxylene diisocyanate (TMXDI), poly(tetramethylene glycol) (PTMG) and polycarprolactone (PCL) and different mole ratio of dimethylol proponicacid (DMPA). The effect of ionic contents in the solvent-free waterborn polyurethane on thermal, mechanical properties and adhesion strength were studied. Glass transition temperature (Tg) were in range of $-70{\sim}-50^{\circ}C$ and increased as PCL contents increased in polyol. With more incorporation of PCL and DMPA contents in SWPU, tensile strength, adhesion strength and heat resistance of SWPU increased, while the elongation decreased.

• Composites Research
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• v.32 no.2
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• pp.96-101
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• 2019

Interfacial adhesion between fiber and resin are related to composites performance, so it is very important to evaluate them accurately. In this study, the interfacial properties of microdroplets under fatigue loading conditions were evaluated. The mechanical properties and interfacial adhesion of epoxy resin with dopamine were studied. Tensile specimens were prepared to evaluate mechanical properties and epoxy microdroplets specimens were used for the evaluation of interfacial adhesion. In addition, in the microdroplet fatigue test, the same diameter of the microdroplet was used and the experiment was performed under the same conditions. As a result, it was confirmed that mechanical and interfacial properties were improved when dopamine was applied to epoxy resin through tensile and microdroplet experiments. It is considered that dopamine improves the degree of curing of the epoxy resin and imparts hydroxyl groups to the epoxy resin to increase the mechanical properties and the interfacial adhesion between the glass fibers.

• 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.

• Fashion & Textile Research Journal
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• v.14 no.1
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• pp.122-129
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• 2012

To develop a waterproof breathable material, we fabricated three kinds of nanofiber web laminates using a massproduced electrospun nanofiber web with different substrates and layer structures. The waterproofness and breathability of nanofiber web laminates were evaluated after repeated launderings and compared with those of conventional waterproof breathable fabrics currently in use, including densely woven fabric, microporous membrane laminated fabric, and coated fabric. The durability of nanofiber web laminates, including adhesion strength, abrasion resistance, tensile strength, and tearing strength, was also assessed and compared with those of conventional waterproof breathable fabrics. The water vapor transmission of nanofiber web laminates increased slightly after repeated launderings, whereas the air permeability somewhat decreased after launderings but still maintained an acceptable level of air permeability. Laundering reduced the resistance to water penetration of nanofiber web laminates, which implies that laminating techniques or substrate materials that could support waterproofness of the laminated structure should be explored. The adhesion strength, abrasion resistance, tensile strength, and tearing strength of nanofiber web laminates were in a range comparable to conventional waterproof breathable materials.