• Journal of Conservation Science
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• v.37 no.2
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• pp.135-143
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• 2021

Conservation treatment that involved filling the lifting parts of wooden cultural heritage is carried out by obtaining wood or wood powder of the same species and mixing it with synthetic resin or natural glue to charge the blank area. Various concentrations and mixing ratios of adhesives and additives are used, depending on the type and condition of the target. Accordingly, in this study, we determined the conditions of the filler suitable for conservation treatment of wooden sculptures with lifted or separated bark in the National Museum of Modern and Contemporary Art. The optimal filler conditions for each adhesive were selected based on drying speed, shrinkage and expansion rates, and physical deformation degree. Then, to verify their actual applicability, these fillers were applied to wood and exposed to high-humidity environment and their cross-sections were observed. The fillers showed stable application in the following order: animal glue, PVAc adhesive, acrylic adhesive. In conclusion, a 1:2 mixture of animal glue and wood powder is a suitable filler for conservation treatment of wooden sculpture with lifted bark. The results of this study suggest appropriate ways to stabilize the bark that was lifted or separated from a wooden sculpture, thus enabling the future conservation treatment of the artworks under similar conditions.

• Journal of the Korean Wood Science and Technology
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• v.34 no.4
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• pp.31-36
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• 2006

This study was conducted to improve the bond strength of plywood bonded with F/U molar ratio urea-formaldehyde (UF) resins modified with the selected FGMDI prepolymer contents for various purposes. The amount of FGMDI was mixed with liquid UF resin at 0 wt% (as control), 2 wt%, 5 wt%, 10 wt%, 25 wt%, and 50 wt% based on the resin solids. As results, in bonding strength, plywood with F/U molar ratio of 1.4 showed the highest value in Type 2 test and all molar ratio UF resins modified with over 25 wt% of the FGMDI showed more than $11kgf/cm^2$, which was satisfied the minimum requirement of KS standard, $7.5kgf/cm^2$, after Type1.5 testing. As F/U molar ratio was increased and the FGMDI addition in the UF resin was increased, average reduction rate of Type 1.5 bonding strength compared with Type 2 was significantly decreased.

• 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 Korean Society of Forest Science
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• v.48 no.1
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• pp.40-50
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• 1980

This research was carried out to examine the substitutional feasibility of low-priced materials produced in waste of forest instead of wheat flour which is extended for plywood adhesives. Wheat, pine bark, wood flour and pine foliage of coniferous trees or poplar foliage of hardwood species were selected and pulverized into 60-100 mesh minute powder after they were dried at $100-105^{\circ}C$ during 24 hours in the drying oven. The prepared particles as above were added to urea formaldehyde resin, urea-melamine copolymer resin and water soluble phenol formaldehyde resin in the ratio of 10, 20, 30 and 50%. After plywoods were processed by the above extending ratios, shear strength of extended plywoods were analyzed and discussed. The results obtained at this study were summarised as follows; 1. In the case of urea formaldehyde resin, both dry and wet shear strength of plywoods extended by wheat flour were shown the highest value. 2. Dry shear strength of urea-melamine copolymer resin was better than that of urea formaldehyde resin on the whole, while plywoods extended by wheat flour were shown excellent results. 3. Among 10% and 20% extensions of urea-melamine copolymer resin, the best results were shown by poplar leaves powder, wheat powder and wood flour. They had no significant difference statistically. 4. In the case of water soluble phenol formaldehyde resin, although dry shear strength of pine leaves powder was higher than that of wheat flour in the ratio of 10%, there was no significant difference between them in the ratio of 10 and 20%. 5. Among 20, 30 and 50% extensions of water soluble phenol formaldehyde resin, wet shear strength of wood flour and bark powder was higher than that of wheat flour. Wet shear strength of wood flour in the ratio of 10% was shown the same tendency as above.

• Journal of the Korean Institute of Gas
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• v.17 no.4
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• pp.45-50
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• 2013

Resorcinol is widely used as a wood, tire adhesives, and a raw material of synthetic dye. This material with white crystals at room temperature, the particulates in the air can form explosive mixtures. It is known to be an explosion hazard when exposed to heat in a confined space. The study was evaluated fire and explosion characteristics of the resorcinol through thermal analysis, thermal stability, dust explosion characteristics, and the minimum ignition energy. From this study, it can be used to provide a safety information in the using and handling process of the resorcinol.

• Elastomers and Composites
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• v.57 no.3
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• pp.100-106
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• 2022

Waterborne polyurethane-acrylate(WPUA) dispersions were prepared by surfactant-free emulsion polymerization in a two-step process. In the first step, polytetrahydrofuran, isophorone diisocyanate, dimethylol proponic acid, and 2-hydroxyethyl methacrylate were used to synthesize a vinyl-terminated polyurethane prepolymer. In the second step, styrene, methyl methacrylate, butyl acrylate, and different multi-functional crosslinkers were copolymerized. 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, and pentaerythritol tetraacrylate were used as the crosslinkers, and their effect on the mechanical and thermal properties of WPUA was investigated. Overall, as the number of functional groups of the cross-linker increased, the gel fraction improved to 79.26%, the particle size increased from 75.9 nm to 148.7 nm, and the tensile strength was improved from 5.86 MPa to 12.40 MPa. In thermal properties, the glass transition temperature and decomposition temperature increased by 9.9℃ and 18℃, respectively. The chemical structures of the WPUA dispersions were characterized by Fourier-transform infrared spectroscopy. The synthesized WPUA has high potential for applications such as coatings, leather coatings, adhesives, and wood finishing.

• Journal of the Korean Wood Science and Technology
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• v.2 no.2
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• pp.25-31
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• 1974

1. Various gluing qualities applying Resorcinol Plyophen #6000 were studied on aiming the strength relationships of laminated woods resulted by single species [poplar (Populus deltoides), larch(Larix leptolepis)], mixed species of (poplar and larch), preservatives, treated poplar the scarf joint with mixed species of poplar and larch and the scarf joint treated with preservatives. 1. 1 On the block shear and on the DVL tension test, the mean wood failure ratio showed an excellent value i.e., above 65% and the tangential strength for larch was higher than that of radial, but it was reversed for poplar as shown in Tables 1 and 2. 1. 2 The lamina treated with Na-PCP reduced slightly the strength but the limited strength allowed for manufacturing laminated wood was not influenced by treating Na-PCP as shown in Tables 3 and 4. 1. 3 The safe scarf ratio in the plane scarf joint was above 1/12 for larch and 1/6 for poplar regard less of the chemical treatment or untreatment as shown in Tables. 5, 6, 7 and 8. 2. In the normal and boiled state, the gluing quality of the laminated wood composed of single[poplar (Populus deltoides), larch (Larix leptolepis)] and double species (poplar and larch) glued with Resorcinol Plyophen #6000 were measured as follow, and also represented the delamination of the same laminated wood. 2.1 The normal block shear strength of the straight and curved laminated wood (in life size) were more than three times of the standards adhesion strength. And, the value of the boiled stock was decreased to one half of the standard shear adhesion strength, but it was more than twice the standard strength for the boiled stock. Thus, it was recognized that the water resistance of the Resorcinol Plyophen #6000 was very high as shown in Tables 9 and 10. 2. 2 The delamination ratio of the straight and curved laminated woods in respect of their composition were decraesed, in turn, in the following order i. e., larch, mixed stock (larch+poplar) and poplar. The maximum value represented by the larch was 3.5% but it was below the limited value as shown in Table 11. 3. The various strengthes i.e., compressive, bending and adhesion obtainted by the straight laminaced wood which were constructed by five plies of single and double species of lamina i. e., larch (Larix leptolepis) and poplar (Populus euramericana), glued with urea resin were shown as follows: 3. 1 If desired a higher strength of architectural laminated wood composed of poplar (P) and larch (L), the combination of the laminas should be arranged as follows, L+P+L+P+L as shown in Table 12. 3.2 The strength of laminated wood composed of laminas which included pith and knots was conside rably decreased than that of clear lamina as shown Table 13. 3.3 The shear strength of the FPL block of the straight laminated wood constructed by the same species which were glued with urea adhesives was more than twice the limited adhesion strength, thus it makes possible to use it for interior constructional stock.

• Journal of the Korean Wood Science and Technology
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• v.34 no.5
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• pp.42-51
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• 2006

The this study, the effect of rice husk flour (RHF) as scavenger on formaldehyde emission rate and formaldehyde content from urea-formaldehyde (UF) resin bonded RHF content wood particleboards (PB). Two type of particle size ($30{\mu}m$ and $300{\mu}m$) of RHF was premixed with the UF resin at 5% and 15% by weight. The performance of UF resins is greatly influenced by the curing characteristics in their curing processing. The curing behavior was monitored activation energy ($E_a$) by DSC and pH variation according to RHF contents. PB with dimensions of $27cm{\times}27cm{\times}0.7cm$ was prepared at a specific gravity of 0.75 using $E_1$ and $E_2$ class UF resins. Formaldehyde emission and formaldehyde content from RHF filled PB bonded with UF resin was measured by 24 h desiccator and perforator method, respectively. RHF causes an increased pH of UF resin. $E_a$ of the modified UF resin decreased independently of RHF particle size. As the pH and the $E_a$ variation of the UF resin containing RHF increased, the amount of formaldehyde content decreased. The formaldehyde emission and formaldehyde content levels of the PB bonded with 15 wt% of $30{\mu}m$ RHF and $E_2$ type UF resin were low and satisfied grade $E_1$, as measured by 24 h desiccator and perforator method. The result of a comparison between 24 h desiccator and perforator test using PB showed that the linear regression analyses show a good correlation between the results for the 24 h desiccator and the perforator tests. The linear regression of a correlation between the desiccator and the perforator was Y=4.842X-0.064 ($R^2=0.989$). RHF was effective at reducing formaldehyde emission and formaldehyde content in urea-formaldehyde adhesives when used as scavenger.

• Journal of the Korean Wood Science and Technology
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• v.38 no.3
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• pp.185-190
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• 2010

This study was focused to make a wooden plate that is engraved with writings or pictures on the medium density fiberboard (MDF), and then to produce a calligraphy-carving artwork by carbonization of the carved MDF. The external appearances and anatomical changes were investigated on the carbonized MDF and aesthetic characteristics was also discussed. No split and no twist were found after the carbonization (at $850^{\circ}C$) of the calligraphy-encarved MDF, shrinkages of the MDF were observed with portions of 21.8% in length, 18.8% in width and 43.5% in thickness, and 69.2% of weight loss with density decrease of 14.8% were observed as well. From the observation of the carbonized board by a scanning electron microscope, specific phenomena were found: the adhesives, surrounding the fiber's surface and pits, were carbonized, the woody fibers were changed smoothly, the pits were opened, the fiber' size was uniformized, and the organization was compacted. By the combination of handmade calligraphy-woodcarving and crack-free carbonizing methods, it was able to find a new method for manufacture carbonized calligraphy-woodcarving artwork. It is concluded that the calligraphy-woodcarving artwork using carbonized board can be a new access for the eco-friendly art that has the advantage of the functionality of charcoal and the aesthetic of calligraphy-woodcarving simultaneously.

• Korean Chemical Engineering Research
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• v.59 no.4
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• pp.548-556
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• 2021

This study was conducted to investigate the applicability of lignocellulosic fiber and coconut shell activated carbon (CSA) for the production of a particulate matter (PM)-reducing air-filter as raw materials to solve the environmental problems of non-woven fabrics. CSA had a good potential to use as a raw material of air-filter for reducing volatile organic compounds as well as noxious metals, and reduction capability of the CSA was 5 times higher than that of wood fiber. Natural adhesives formulated with proteinaceous wastes mostly were applied successfully to fabricate air-filters with the shape of fiberboard. The air-filter fabricated with the minimum target density of 200 kg/m³ and the maximum CSA-content of 40 wt% in fiberboard had a good manageable strength. However, the fiberboard filters was required to make vent-holes for improving an air-permeability of the filters. Size of the CSA particles was adjusted to greater than 2 mesh with the consideration of strength and formability of the fiberboard. Three-layers fiberboard that only wood fiber and the mixture of wood fiber and CSA were formed in the surface and middle layers, respectively, was determined to the optimal condition for the production of air-filters. In addition, traditional Korean paper handmade from mulberry trees (TKP) showed a good PM-reducing property as an air-filter. It is concluded that air-filtering set composed of fiberboard with vent-holes and TKP instead of conventional air-filters made with non-woven fabrics can be used as a filter for reducing the concentrations of PM, VOC and noxious metals existed in indoor and outdoor spaces.