• Polymer Science and Technology
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• v.22 no.3
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• pp.230-236
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• 2011

• Journal of the Korea Furniture Society
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• v.14 no.2
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• pp.1-12
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• 2003

This study was carried out to determine the mechanical and physical properties of particle boards glued with condensed tannin (Wattle Tannin) powder that was single-molecule phenolic compounds like powdered phenolic resin. Our findings are; 1) It is necessary to spray water on the chip surfaces for effective application of powdered -form tannin resin. It shows that the best and optimum mat moisture increase is 14% of water spray on the surface of chips for developing PB properties. 2) In general, for both liquid and powdered tannin adhesives, their physical and mechanical properties has been proportional to the increase of resin level. But, the most efficient addition ratio is 16% of resin on dry basis. Specially, it is found that the resin level influences on the amount of free formaldehyde emission. The higher the resin level is, the lower the emission is. These phenomena seem to result from the increase of hexamine or formaline in the adhesives used as a hardener, that reduce the free-formaldehyde amount by reaction of tannin of poly-molecule and water. 3) The optimum condition for manufacturing PBs is the condition of hexamine of 5% and formaline of 6% in mechanical and physical properties. Hexamine is superior to formaline in mechanical and physical properties along with the control of the free formaldehyde emission amount. The result of NaOH's addition is insignificant in all experiments of both mechanical and physical properties.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.7
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• pp.673-677
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• 2016

Recently, engineering applications have started to adopt solutions inspired by nature. The peculiar adhesive properties of gecko skin are an example, as they allow the animal to move freely on vertical walls and even on ceilings. The high adhesive forces between gecko feet and walls are due to the hierarchical microscopical structure of the skin. In this study, the effect of metal coatings on the adhesive strength of synthetic, hierarchically structured, dry adhesives was investigated. Synthetic dry adhesives were fabricated using PDMS micro-molds prepared by photolithography. Metal coatings on synthetic dry adhesives were formed by plasma sputtering. Adhesive strength was measured by pure shear tests. The highest adhesion strengths were found with coatings composed of 4 nm thick layers of Indium, 8 nm thick layers of Zinc and 6 nm thick layers of Gold, respectively.

• Journal of the Korea Furniture Society
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• v.10 no.1
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• pp.23-32
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• 1999

The ultrastructural characteristics of shear fracture surfaces of laminated wood prepared from major four Korea wood specimens were examined. Commercial urea and urethan resin were used as adhesives for laminated woods of both homospecies and heterospecies. The morphology of fracture surface was observed using an optical microscopy and scanning electron microscopy. Three anatomical failure types were recognized : intercell failure, intrawall failure and transwall failure. In dry specimen, failure occurred mainly in woods. Laminated woods of softwoods showed mostly intrawall failure and transwall failure of tracheids, and them of hardwoods indicated mainly intrawall failure and interwall failure. Laminated woods prepared with urethan resin showed coarse fracture surface, on the other hand, those prepared with an urea formaldehyde resin had clean surface. In wet specimen, failure occurred dominantly in glue line. Intrawall failure and flags were characterized in laminated wood prepared with urethan resin. In heterospecies laminated woods, failure was occurred mainly in softwood. Consequently, fracture morphology of laminated wood may be influenced by adhesives, moisture content, species and anatomical characteristics.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.38 no.1 s.113
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• pp.34-44
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• 2006

A new composition of paper coating adhesives was prepared by using a nano-filler of an organically-modified montmorillonite (O-MMT). The new O-MMT coating adhesives were applied to the paper, and the properties of coated papers including surface morphology, optical and physical properties, and printing properties were investigated. The use of O-MMT improved the mechanical properties, such as folding endurance, tearing strength, and tensile strength, while the surface smoothness decreased. It decreased especially when the dosage was high enough, approximately above 6 parts. The printing properties such as wet- and dry-pick were enhanced with addition of O-MMT.

• Journal of the Korean Wood Science and Technology
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• v.24 no.2
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• pp.42-45
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• 1996

A residue from the newsprint waste was investigated as a filler in adhesive for bonding southern pine plywood. The residue was prepared by drying the wet residue to 8% moisture content and grinding the dry material using a laboratory Wiley mitt with a 75-${\mu}m$(200-mesh) screen. The residue was compared to a commercial filler commonly used in structural plywood adhesives. A total of 48 three-ply panels. 12.7mm nominal thickness and 0.3 by 0.3 m in size, were fabricated at two press times(4 and 5 min) and three assembly times(20, 40 and 60 min). Evaluations of the residue were carried out by performance tension shear tests after two 4-hour boil accelerated aging tests on plywood. The test results included tension shear strength and estimated wood failure values. All plywood made with the residue filler were comparable to the control-bonded plywood. These results indicate that residue from the newsprint waste streams would be suitable as filler for plywood adhesives.

• Journal of Technologic Dentistry
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• v.37 no.1
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• pp.17-21
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• 2015

Purpose: In this study, Spreadability of denture adhesive in accordance with the saturation level of saliva, respectively, by using the resin plate and the glass was measured thickness and Spreadability. Methods: Examine the spreadability of denture adhesive in accordance with the saturation level of saliva, respectively, by using the resin plate and the glass was measured thickness and Spreadability. Also, by measuring the adhesive strength according to the amount of saliva, and the edentulous patients using denture adhesive and dry mouth patients attempt to provide clinical information of the denture adhesive. Therefore, by using the relatively low shrinkage cold curing resin, after fabricating specimen of plate form, for 7 days, it was immersed in water. Results: For the control group only denture adhesive, an artificial saliva for the experimental group were injected in $0.1m{\ell}$, $0.2m{\ell}$ and $0.3m{\ell}$ of the denture adhesive on the surface, experimental results of the investigation of the 10 times the tensile bond strength of the specimens in each group was obtained the following results. Conclusion: As the time to pressure increase in the same amount of saliva was found that the amount coming out of the denture adhesive, as the amount of saliva in the same pressure increase coming out of many denture adhesives. And the greater the pressure came out a lot of denture adhesives. Spreadability in measuring saliva contact with $0.1m{\ell}$ and $2m{\ell}$ and $3m{\ell}$ group pressured the diameter of the circular was the denture adhesive is small when compared to the group without adding the pressure of 2kg and 3kg put the saliva. The size of the circle is the same amount of saliva denture adhesive spread more pressure showed a greater increase.

• Journal of the Korean Wood Science and Technology
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• v.26 no.3
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• pp.48-52
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• 1998

Residues such as walnut, pinenut and peanut shells were used as a filler in adhesive for bonding radiata pine plywood. The nutshell residues were prepared by simply drying to 8% moisture content and grinding the dry material using a laboratory Wiley mill with a $75{\mu}m$ (200 mesh) screen. The nutshells residues were compared to a commercial filler commonly used in adhesives by the structural plywood and laminated veneer lumber industry in the United States. The adhesive mixes were made by following the recommended procedure of Georgia-Pacific Resins, Inc., using phenol-formaldehyde resin. For each filler type, three-ply plywoods, 6 mm nominal thickness and 30 by 30 cm in size, were fabricated at two press times (4 and 5 min) and around 30 minute assembly time. Evaluations of the nutshell residues were carried out by tension shear tests after cyclic boil tests on plywood. The results of the performance test included tension shear strength and wood failure. All plywoods made with the nutshell fillers were comparable to those made with the control filler. These results indicate that nutshell residues would be suitable as filler for plywood adhesives.

• Restorative Dentistry and Endodontics
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• v.28 no.1
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• pp.11-22
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• 2003

This study compared the dentin adhesion to composite resin according to air-dry, blot dry, application of rewetting agent on air-dry or blot dry dentin surface by microleakag test and SEM observation. For microleakage test, class V cavity preparations with dentinal margins were prepared on both buccal and lingual surfaces of 40 extracted human molars. For SEM observation, occlusal dentin of 20 extracted human molars were exposed. After etched the dentin, prepared teeth were randomly divided into four groups; D group: air dry for 10-15 sec., B group: blot dry with moist cotton pellet, D-R group: air dry and rewet with Aqua-Prep F for 20 sec., B-R group: blot dry and rewet with Aqua-Prep F for 20 sec. Treated cavities and surfaces were filled or constructed using One-Step adhesives and Aelitefil composite resins. Specimens were stored in distilled water for 24 hours. For microleakage test, the specimens were thermocycled and soaked into 2% methylene blue. The specimens were sectioned longitudinally and evaluated for microleakage under steromicroscope. The data were statistically analysed by Kuskal-Wallis Test, Mann-Whitney and Wilcoxon signed ranked tests. For SEM observation, the specimens were bisectioned mesiodiatally. After decalcified and deproteinized, specimens were observed under SEM. The results of this study were as follows; 1. The microleakges on dentinal margin were the highest in D group compared with B group, D-R group, and B-R group(p<0.05). But there was no significant difference between B group, D-R group and B-R group. 2. D group showed gap and a few resin tags between dentin and composite resin. 3 B group, D-R group, and B-R groups showed close adaptation between dentin and composite resin. It showed that resin rags in B group were numerous and long, in D-R group were few and short, in B-R group were numerous and short or long. 4. Adhesive layer showed in D-R group ($10{\;}\mu\textrm{m}$) and B-R group ($3{\;}\mu\textrm{m}$) In conclusion, use of rewetting agent to dry dentin was efficient to dentin adhesion, also it did not provide reverse effect on blot dry dentin.

• Journal of the Korean Wood Science and Technology
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• v.12 no.2
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• pp.35-43
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• 1984

This study was carried out to investigate the block shear strength of the 2ply laminated wood composed of Pinus thunbergii with ureaformaldehyde resin as adhesives according to pressure (6, 9, 12, 15kg/$cm^2$), pressing time(5, 10, 20, 30 hrs.), amount of spread(54, 108, 217, 324g/$cm^2$), hardener(10, 20, 30, 40% of 10% $NH_4CL$ on resin) and extender(0, 5, 10, 15% wheat flour on resin), and the bending strength and bending young's modulus of laminated beam according to the number of ply. The results were summarized as follows; 1. According to pressing pressure with amount of spread 217g/$cm^2$ both dry and wet shear strength of laminated wood showed the highest in 15kg/$cm^2$, and hot-cold soaking treatment showed the highest in 9kg/$cm^2$, while all shear strength of dry, wet and hot-cold soaked laminated wood have been reduced with the increasing of pressing time. 2. According to amount of spread, adhesion strength with the dry, wet and hot-cold soaking treatments revealed the highest in 217g/$cm^2$ and have been reduced under or over 217g/$cm^2$ of spread. 3. According to addition of hardener and extender, all shear strength of laminated block with the dry, wet and hot-cold soaking treatments have been reduced in increasing of addition amount of hardener and extender. The bending strength of beam according to the number of ply showed the highest in 2ply laminated wood and horizontal loading beam to glue line had the higher in strength than the vertical loading.