• Journal of the Korean Wood Science and Technology
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• v.35 no.2
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• pp.61-68
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• 2007

The applicable scope of adhesives in the current society is broad and currently, several types of PVAc resin are sold in the market for adhesives. PVAc resin is primarily used for wood works and paper adhesion. However, the PVAc resin itself has the disadvantages that its viscosity is highly temperature- dependent and the work condition and viscosity get worse at the low temperature in the winter seasons. Although phthalate-based plasticizer is used to complement these disadvantages, adhesion strength and heat-resistance are weakened by adding the phthalate-based plasticizer and in the winter period, the amount of quantity should be increased. Also in a high-density product, it worsens the work condition by causing a rise of viscosity and delays curing and in a low-density product, it worsens the storage stability by causing separate precipitation. In addition to these, the phthalate-based plasticizer as a material of causing environmental hormones is currently restricted in the advanced countries for its amount of use and also in the domestic market, it is necessary to prepare for the situation. This study has not only eliminated the disadvantages of PVAc resin emulsion without adding a phthalate-based plasticizer of causing these problems, but also synthesized the PVAc resin for timber adhesion that is excellent in woodwork, thermal-resistance, water-resistance, storage stability, and adhesion performance. As the result, it has proven an excellent performance in thermal resistance, water resistance, storage stability, and minimum film forming temperature.

• Journal of the Korean Wood Science and Technology
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• v.48 no.3
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• pp.303-314
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• 2020

Gambir is a non-wood forest product with a potential of being used as wood adhesive, due to about 33% catechin in it. Meanwhile, catechins and sucrose have not been studied as adhesives. Therefore, basic characteristics of gambir-sucrose adhesives were investigated. In this research, adhesives were prepared by dissolving gambir and sucrose in distilled water, at different blending ratios of the gambir/sucrose such as 100/0, 75/25, 50/50, and 25/75 wt%. Furthermore, gas chromatography-mass spectrometry (GC-MS) was employed to determine the gambir chemical compositions, and Fourier transform-infrared (FTIR) spectroscopy was carried out to identify chemical bonds. Particleboards with a target density of 0.8 g/㎤ were then manufactured by hot-pressing for 10 min at 200℃. The internal bond (IB) strength of particleboard was subsequently measured. Based on the GC-MS analysis, 31.11% of catechin was identified. In addition, the viscosity, density, solid content, and gelation time of the adhesives, and insoluble matter content (IMC) in boiling water were 7.30~33.24 mPa.s, 1.2~1.3 g/㎤, 25.56~28.44%, 73~420 min, and 29.75~62.10%, respectively. Adding sucrose to the adhesive was observed to raise the IMC from 49.05 to 62.10%, at 180℃ and 200℃. FT-IR analysis showed that the gambir absorption peaks occurred at approximately 1620 cm^-1, assigned to the C=O stretching of 5-hydroxymethylfurfural, which tended to increase with the addition of sucrose. The reaction between gambir and sucrose was observed in the form of the dimethylene ether bridge. The 25/75 wt% gambir-sucrose adhesives and 200℃ hot-pressed temperature resulted in the highest IB strength (0.89 MPa), and met the requirement of JIS A5908-2003 type 18. Consequently, the gambir-sucrose adhesive could be used as a particleboard adhesive.

• Journal of the Korean Wood Science and Technology
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• v.47 no.3
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• pp.253-264
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• 2019

This study characterized the chemical compounds in tannin from mangium (Acacia mangium) bark extract and determined the physical-mechanical properties of glued laminated timber (glulam) made from sengon (Falcataria moluccana), jabon (Anthocephalus cadamba), and mangium wood. The adhesives used to prepare the glulam were based on mangium tannin and phenol resorcinol formaldehyde resin. Five-layer glulam beams measuring $5cm{\times}6cm{\times}120cm$ in thickness, width, and length, respectively, were made with a glue spread of $280g/m^2$ for each glue line, cold pressing at $10.5kgf/cm^2$ for 4 h and clamping for 20 h. Condensed mangium tannin consisted of 49.08% phenolic compounds with an average molecular weight of 4745. The degree of crystallinity was 14.8%. The Stiasny number was 47.22%. The density and the moisture content of the glulams differed from those of the corresponding solid woods with mangium having the lowest moisture content (9.58%) and the highest density ($0.66g/cm^3$). The modulus of rupture for all glulam beams met the JAS 234-2003 standard but the modulus of elasticity and the shear strength values did not. Glulam beams made with tannin had high delamination under dry and wet conditions, but glulam made from sengon and jabon wood met the standard's requirements. All glulam beams had low formaldehyde emissions and were classified as $F^{****}$ for formaldehyde emissions according to the JAS 234 (2003) standard.

• Journal of the Korean Wood Science and Technology
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• v.24 no.4
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• pp.56-63
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• 1996

This study was to manufacture thinned wood of Larix leptolepis Gordon into Oriented Strand Board(OSB) with Urea-Formaldehyde Resin. The OSB was made of four kinds of strand in slenderness ratio 150 ; thickness $0.3{\pm}0.05mm$, $0.4{\pm}0.05mm$, $0.5{\pm}0.05mm$ and $0.6{\pm}0.05mm$, respectively length 45mm, 60mm, 75mm and 90mm. Target densities were 0.65gr/$cm^3$, 0.75gr/$cm^3$ and 0.85gr/$cm^3$. The stepwise 9 minutes-multi-pressing schedule in the maximum pressure 40kgf/$cm^2$, the minimum pressure 10kgf/$cm^2$ was applied for $400mm{\times}390mm{\times}12mm$ board at the temperature of $150^{\circ}C$ in a hot press. In MOR The OSB of thin strand thickness $0.3{\pm}0.05mm$(length 45mm) and density 0.85gr/$cm^3$ was the highest. The strand thickness had more effect on MOR than the strand length. In strand thickness $0.4{\pm}0.05mm$(length 60mm) and density 0.85gr/$cm^3$ was the highest MOE. The strand thickness and length had adverse effects on MOE each other. At internal bonding. The OSB of strand thickness $0.3{\pm}0.05mm$(length 45mm) and board density 0.75gr/$cm^3$ showed the highest value. OSB had higher IB value with thinner strand thickness. The thinner strand thickness showed the lower thickness swelling in turn $0.3{\pm}0.05mm$(length 45mm), $0.4{\pm}0.05mm$(length 60mm), $0.5{\pm}0.05mm$(length 75mm). $0.6{\pm}0.05mm$(length 90mm). Target densities 0.75gr/$cm^3$ 0.65gr/$cm^3$, 0.85gr/$cm^3$ showed in turn lower value. Finally, The OSB made of thinned wood of Larix leptolepis Gordon showed good results in laboratory experiment.

• Journal of the Korean Wood Science and Technology
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• v.28 no.4
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• pp.83-93
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• 2000

This study was carried out to improve the physico-mechanical properties of board products by applying the technique of high frequency heating, and find out the optimum conditions of high frequency heating, compared with the technique of hot platen heating. The possibility of isocyanate resin application to board production was also considered to solve the problem of free formaldehyde emission from urea resin which is generally used in wood industry. For this study, 30 mm thick MDP (medium density fiberboard) with isocyanate resin were manufactured by the techniques of hot platen heating, high frequency heating and the combination techniques of both heating methods, and compared in several point of views.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2011.10a
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• pp.43-47
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• 2011

In woody waste separated from municipal solid waste, medium density fiberboard was major contributors with particleboard, paper, plywood and log, with different composition based on collected period. In chemical compositional analysis of woody waste, it was similar to softwood based on carbohydrate composition analysis. Based on the carbohydrate composition, saccharified solution from MWW could be good resource for biorefinery.

• Journal of the Korean Wood Science and Technology
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• v.19 no.3
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• pp.27-34
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• 1991

Screw withdrawal test was carried out on the face and edge of domestic particleboard and medium density fiberboard in order to evaluate optimum pilot hole diameter. The obtained results were as follows: 1. Maximum withdrawal strengths on the face and edge of particleboard were obtained with pilot hole diameters at about 50% of root diameters of screw. 2. Maximum withdrawal strength on the face and edge of medium density fiberboard were obtained with pilot hole diameters that were about 60% and 50% of root diameters of screw, respectively. 3. Withdrawal strength showed about 91% of maximum withdrawal strength when pilot holes were not pre bored at particleboard. but when pilot holes at 90% of root diameter of screw withdrawal strength showed about as 51.3% of maximum withdrawal strength. 4. Withdrawal strength showed about 88% of maximum strength when pilot holes were not used, but withdrawal strength indicated 55.4% of maximum strength in case of 90% of root diameters of screw. 5. Maximum withdrawal strength on the face of particleboard was about 70.5% higher than that of the edge, and however medium density fiberboard was about 19.6% higher than that of the edge.

• Journal of the Korean Wood Science and Technology
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• v.26 no.1
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• pp.87-96
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• 1998

The bending performances were evaluated at the radiata pine plywood through veneer compositions encompassing veneer quality, ply-numbers and overlays of the high density- or medium density-phenol resin impregnated sheets (hereafter abbreviated as resin sheets) on the raw plywood. In addition, a prediction on the bending MOE of veneers and plywoods was carried out by the nondestructive testing with stresswave timer. The summarized results were as follows: I. Bending strength and bending MOE of resin sheets-overlaid plywoods in parallel surface grain direction through 5 and 7ply were increased by 13 to 45% and 17 to 34%, respectively. Resin sheets-overlay occurred an increasing effect of the strength efficiency i.e. strength perpendicular-to-grain direction versus that parallel-to-grain direction, showing the phenomenon that the plywood strength becomes greater at the perpendicular-to-grain direction of 7ply than at that of 5ply. Displacement at bending failure had a greater trend at 7ply than at 5ply, and was decreased by resin sheets-overlay. 2. After the nondestructive bending MOEs were measured for individual veneers, these veneers were rearranged in plywood-manufacture. In these plywoods, including resin sheets-overlay, the actual MOE was predictable with feasibility of $R^2$=0.53, and also the nondestructively-evaluated MOE was lower by 20% in raw plywood, and higher 20% in LVL than actual bending MOEs.

• Journal of the Korean Wood Science and Technology
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• v.37 no.6
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• pp.517-523
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• 2009

Repeated impregnation and carbonization processes were performed to prepare high-density woodceramics using a sawdust board. The physical properties were investigated to confirm morphological and structural changes of one-time and two-time phenolic resin-treated and carbonized woodceramics. As comparing between one-time and two-time carbonized woodceramics, the weight and the density of the two-time carbonized woodceramics decreased with an increase of the carbonization temperature. When the carbonization temperature was $600^{\circ}C$, the weight increased by 21.7% and density increased by 20.6% from $0.68g/cm^3$ to $0.82g/cm^3$, respectively, as a maximum value.

• Journal of the Korean Wood Science and Technology
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• v.36 no.3
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• pp.39-46
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• 2008

Repeated impregnation and carbonization processes were performed to prepare high-density woodceramics using a sawdust board. The physical properties were investigated to confirm morphological and structural changes of one-time and two-time phenolic resin-treated and carbonized woodceramics. As comparing between one-time and two-time carbonized woodceramics, the weight and the density of the two-time carbonized woodceramics decreased with an increase of the amount of impregnated phenolic resin. In addition, when the amount of impregnated phenolic resin was about 40% in these woodceramics, the two-time carbonized woodceramics showed higher weight (23.8%) and density (30.0%) than the one-time treatment.