• Journal of the Korean Wood Science and Technology
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• v.33 no.5 s.133
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• pp.57-65
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• 2005

Following our previous reports for finger-jointed woods with various finger profiles studied for the efficient use of small diameter logs and woods containing various defects, twelve types of finger-jointed woods glued with three kinds of adhesives and with two sizes of finger pitches were made with sitka spruce and red pine. The effects of the adhesives and finger pitches on bending creep performances of finger-jointed woods were investigated. The shape of creep curves differed among the used adhesives and finger pitches of finger-jointed woods for both tested species. Their creep curves showed a linear behavior beyond about one hour, and the N values fitted to power law increased with increasing finger pitches. The initial deformation increased with increasing finger pitches, regardless of the tested species and kinds of adhesives, whereas the effect of finger pitches on the creep deformation was not clear. For finger-jointed woods glued with polyvinyl acetate (PVAc) resin, creep failure occurred in 106 hours after the load was applied. And the difference of the creep compliance between finger-jointed woods glued with resorcinol-phenol formaldehyde (RPF) resin and aqueous vinyl urethane (AVU) resin was small. The ratios for creep performances of finger-jointed woods glued with RPF resin and AVU resin versus solid wood were higher in creep deformation than initial deformation for both species, and the difference between both adhesives was not found. The relative creep decreased with increasing finger pitches, and the marked differences was not found between RPF resin and AVU resin.

• Journal of the Korean Wood Science and Technology
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• v.35 no.1
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• pp.27-35
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• 2007

This experiment was carried out to investigate the appearance and surface gluing characteristics of laminated boards overlaied with teak sliced veneer, printing paper, wall paper, cotton cloth, and wool cloth, The overlaying sheets were glued on the laminated boards with polyvinyl acetate emulsion adhesives and the species for laminated boards was red pine. The obtained results are summarized as follows; in case of the teak sliced veneer overlaied boards, the appearance quality was very good and showed the first grade of KS standard. but the delamination rate was 44.0% and 895% for cold water or warm water dipping treatments, respectively, so the wet gluing properties were very bed. In the case of the paper or cloth overlaied boards, the appearance quality was same good and showed the first grade of KS standard, but their delamination rate was 10~20% and 39.3~49.0 for cold water or warm water dipping treatments, respectively, so the wet gluing properties were bed, relatively better than sliced veneer overlaied boards. The present work showed that appearance of laminated boards overlaid with several sheets appeared quite positive in terms of secondary gluing qualities of laminated boards, suggesting that sliced veneer, paper, and cloth would be appropriate for the overlaying materials of laminated boards.

• Journal of the Korean Chemical Society
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• v.7 no.2
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• pp.96-105
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• 1963

The weight decrease curves of 18 kinds of polymers have been measured by thermobalance at the same condition where temperature is increased $1^{\circ}C$ per minutes under nitrogen or air atmosphere. The curves are further differentiated to obtain rate curve of weight decrease. Those curve offer a method to compare relative thermal stability, effects of oxygen or modes of thermal degradation of polymers qualitatively. The curves could be classified into following four types: Polystyrene, polymethylmethacrylate and acetal polymer belong to the first type. Those polymers depolymerize mainly into corresponding monomers, weight decrease curves are steepy up to perfect vaporization of polymers and rate curves show a relatively sharp peak. (Type I) Polyvinyl chloride represents the second type. This polymer decomposes with splitting off of hydrogen chloride. The thermogravimetric curve rises rapidly at first, then level off at the moderate weight decrease and gradually rises. Polyvinyl acetate also belongs to this class. (Type II) The modification of the second type is represented by polyester. The curve at the early stage is less steep, the leveling off at the next stage is less clear and the final rising of the curve is steeper than the normal second type. Polyamide, polyurethane, and polycarbonate belong to this type. (Type II') The thermal decomposition of the third type polymers is more complex than that of others. Various irregular chain scissions including side chain splitting and depolymerization to monomers occur simultaneously. The weight of the polymer decreases gradually and the rate curve does not show sharp peaks. Polyvinyl alcohol and diene polymers belong to this type. (Type III) Generally, polycondensation polymers are more stable toward heat than addition polymers and polymers having aromatic nucleus show good thermal stability. Polymers having tertiary carbon atoms such as polystyrene or polypropylene and acetal resin start decomposition under airatmosphere at the temprature below $50^{\circ}C$ or more of the temperature where the polymers start decomposition under nitrogen atmosphere.

• Journal of the Korean Wood Science and Technology
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• v.32 no.6
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• pp.57-66
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• 2004

To study the efficient usage of small diameter logs and woods containing defects such as knots, slope of the grain and decay, six types of finger-jointed woods with various finger profiles were made of poplar, pine and oak with different density. We investigated the effect of finger profile on static bending strength performances of finger-jointed woods. The efficiency of bending MOE, MOR and deflection showed the highest value in poplar finger-jointed wood with the lowest density of three species, and the lowest value in oak finger-jointed wood with the highest density of three species. The values markedly decreased with increasing finger pitch for finger-jointed wood glued with polyvinyl acetate (PVAc) resin for all tested species, whereas for the finger-jointed wood glued with resorcinol-phenol formaldehyde (RPF) resin, the influence of finger pitch on the efficiency of MOE was not found in all tested species, and those on the efficiency of MOR and deflection indicated the same trend as finger-jointed wood glued with PVAc resin in the case of pine and oak finger-jointed wood with higher densities. It was found that the values tended to decrease with increasing density of species on the whole and the desirable finger pitches were L (6.8 mm) for poplar, M (4.4 mm) for pine and S (3.5 mm) for oak in a view of economy. For finger-jointed wood glued with PVAc resin, the fitness between a tip and a root width of a pair of fingers δ of 0.5 mm indicated the highest efficiency of MOE for all species. And, the influence of δ on MOR was only found in oak finger-jointed wood glued with RPF resin and the desirable δ value for oak was 0.1 mm. However, it was found that the influence of δ on the strength performance was very small.

• Journal of the Korea Institute of Building Construction
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• v.12 no.5
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• pp.539-547
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• 2012

To manufacture laminated wood with improved mechanical properties by providing uniform adhesiveness, the adhesive was applied and the plate adhesive was laminated on the wood surface. Then, after laminating the wood on the top part of the adhesivebond, it was heated and dried while the adhesive was stiffened using microwaves, and the test piece was manufactured by compressing it with the press machine for thirty minutes. The temperature and the water content were examined according to the heating time of the wood heated with the microwave, and testing was conducted on the shear strength and flexural strength of the wood. In addition, the microstructure of the adhesive bond between the wood was recorded to confirm the penetrabilityinto the wood structure for the adhesive. After the test was conducted, it was found that the test piece manufactured with wood that has its water content leveled with the microwave heating showed improved shear strength and bending strength compared to the standard test piece. With regard to adhesives, liquefied polyvinyl acetate resin and plate's PVB resin were found to have superior adhesive strength. Also, after filming the cellular microstructure, it was found that when the laminated wood is heated with microwaves, the infiltration of the adhesive into the inside of the wood becomes easy, which makes it effective for improving adhesiveness.

• 보존과학연구
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• s.29
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• pp.255-278
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• 2008

Considering the physical quality of the wall body in this study we tried to select a replenishing that is proper for filling the cracked part of the painting wall layer and apply the natural adhesives that have traditionally been used, investigating whether it is possible to substitute those for the chemical adhesive which is used at present time. The result of this study showed the red algae adhesive was, in a weathering environment, as safe as the synthetic resin originated from the polyvinyl acetate which is used generally on the present spot, and it was concluded that although the starch adhesive displayed its superiority in enhancing the strength of the earth mortar and its work disposition, it seemed proper for it to be used as a filling adhesive for the first or midterm layer because it showed a surface hardening phenomenon. And also the glue and fish glue were judged they were not qualified as a filling adhesive due to mold occurring in a environment of high moisture that is a biological problem, showing at same time a weak physical feature in a weathering environment. Therefore it would be possible to use the red algae adhesive or starch one substituting them for the original one sold on the present market, if among natural adhesives the weak points of the them were to be corrected.

• Journal of the Korean Wood Science and Technology
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• v.52 no.4
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• pp.383-392
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• 2024

Laminated bamboo is an engineered bamboo technology to maintain its mechanical durability for both construction and furniture materials. This study was conducted to assess the properties of laminated bamboo made from Betung bamboo at different culm positions and laminate orientations. The materials used in this study were 4-year Betung bamboo (Dendrocalamus asper) obtained from a community forest in Yogyakarta and polyvinyl acetate resin as adhesive. Two factors were applied for this study, i.e., culm position (lower, middle, and upper) and laminate orientations (vertical and horizontal direction). To examine the mechanical properties, a static bending test and the hardness test were performed in accordance with ASTM D1037-99. Moisture content and density were determined in accordance with BS 373-1957. The results indicated that there was no interaction between the culm position and laminate orientation on the moisture content, density, static bending properties and hardness. The culm position affected the static bending and hardness, with the higher position of the culm resulting a greater strength. The laminate orientation also affected the strength of laminated bamboo, with the vertical direction resulting in higher strength than the horizontal.

• Journal of Conservation Science
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• v.32 no.2
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• pp.167-178
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• 2016

Despite the size layer is an important part for conserving the artworks in the configuration of oil painting, the conservation scientific approaches of that have not been made yet. Therefore, this study produced standard samples on the basis of the analysis results of oil painting works, and carried out the evaluation of functions of the size layer materials. As a result of literature material, traditionally, animal glue was used for the size layer, whereas synthetic resin have been used in combination with animal glue since the modern age, in particular, it was identified that Polyvinyl Acetate(PVAc) was in general use. As a result of analysis of oil painting works, size layer was detected on the support and it was identified as animal glue. As a result of analysis based on Funaoka canvas for ground, it showed that the lead oxide and the titanium dioxide were the main constituents. On the basis of these results, standard samples were produced. As a result of evaluation on the functions of the size layer materials, in the case of the animal glue, stable result was observed in the shrinkag expansion rate, whereas slight weakness was observed in moisture proofing, color, and tensile strength, and dense cracks were found on surface. As for PVAc(A), moisture proofing, color, and the tensile strength exhibited stable results. Higher shrinkage rate was observed and the cracks with wide gaps were found on surface. As for PVAc(B), tensile strength, shrinkage expansion rate, and surface observation showed stable results, whereas moisture proofing property showed poor results. Different aspects were observed in each experiment, and this phenomena were considered to be due to the density and the adhesion properties between the hydrophilic and hydrophobic molecules in the size layer materials. The results are expected to be used as materials for the oil painting work conservation henceforth.

• Journal of Conservation Science
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• v.29 no.1
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• pp.81-92
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• 2013

In the past, European material and method were applied to conservation of Buddhist mural paintings in Korea. At that time, there were inadequate to selection of materials in consideration of porosity and hydrophilicity, therefore insufficiency to assessing their suitability for materials. The treatment result of mural painting are dissatisfied with consolidation of painting layer using synthetic resin. Therefore, it has experimented on applying fixative for reinforcement of painting layer on Buddhist mural painting in order to establish the effects of conservation. In relationship of binder's viscosity, adhesion and penetrating depth, adhesion increased in high-viscosity specimen whereas it decreased in low-viscosity specimen. While the binder's penetrating depths show similar patterns, the surface's response and combination adjacent to painting layer have differences. Animal glue and methyl cellulose (MC) shows excellent performance in their reaction with soil and painting layer. It is estimated that the fixative penetrates deep into soil to produce a stable fixing effect. The viscosity of polyvinyl acetate resin (PVAc) and acrylic resins are low, and thus penetrates well into soil, but they adhere poorly to soil.