• Journal of the Korean Wood Science and Technology
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• v.38 no.6
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• pp.541-546
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• 2010

This study was to investigate the dry bond strengths of the plywoods manufactured with 3 hours ozonized soybean oil (SBO)/polymeric methylene diphenyl diisocyanate (pMDI) adhesive at mid and high curing temperature. In results of the dry bonding strengths of the 3 hrs-ozonized SBO mixed with pMDI at high curing temperature were respectively the strengths of weight ratio of 3hrs-ozonized SBO : pMDI, 1 : 0.5, 4.74 kgf/$cm^2$, 1 : 0.75, 7.14 kgf/$cm^2$ 1 : 1, 9.29 kgf/$cm^2$, 1 : 2, 16.53 kgf/$cm^2$, 1 : 3, 17.42 kgf/$cm^2$, and 1 : 4, 16.75 kgf/$cm^2$. Therefore, it was found that the equivalent ratio was formed approximately between 3 hrs-ozonized SBO : pMDI 1 : 2 and 1 : 3. The dry bonding strengths of the 3hrs-ozonized SBO mixed with pMDI at medium curing temperature were respectively the strengths of weight ratio of 3 hrs-ozonized SBO : pMDI, 1 : 0.5, 3.16 kgf/$cm^2$, 1 : 0.75, 6.13 kgf/$cm^2$ 1 : 1, 8.18 kgf/$cm^2$, 1 : 2, 11.82 kgf/$cm^2$. In this experiment the higher bonding strength at high curing temperature was shown approximately between 3 hrs-ozonized SBO : pMDI 1 : 2 and 1 : 3. If this wood adhesive is used at high curing temperature, it is possibile to bond the plywoods.

• Korean Journal of Heritage: History & Science
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• v.54 no.4
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• pp.78-89
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• 2021

Organic residues analysis is an analysis method that reveals the types of organic material samples by using the characteristic that main components constituting substances are different depending on the species of animals and plants. In this study, scientific analysis of the organic residues attached to wood coffins in the Joseon Dynasty Hoemyo excavated from the site of Singok-dong, Uijeongbu was used to identify the types of remnants and to use them as information to restore the uses of organic materials and the way they lived in the past. As a result of FT-IR analysis of the residue attached to the inside of the wood, it was estimated to be a natural plant resin material. In addition, as a result of analysis by GC-MS to confirm the characteristic factors of natural resins, diterpenoids (abietane) and pimaran (pimarane), such as dehydroabietic acid and pimaric acid (diterpenoid) compounds, and saturated and unsaturated fatty acid components were detected together. Diterpenoid compounds are components mainly found in Pinaceae resins. It is confirmed in the literature that rosin, a representative material of Pinaceae resin, was used as an adhesive material. Considering the situation where an organic material remained at the joint of the wood, the organic material attached to the wood is judged to be an adhesive material made of Pinaceae resin. In addition, the fatty acid component detected together is a component derived from plant oil, and it is presumed to be made by mixing rosin and oil as recorded in previous studies. This study confirms that organic residues remain in the burial environment without losing their characteristics. It is expected that scientific analysis of organic residues will be conducted in the future to accumulate information necessary for the interpretation of past living culture.

• Journal of the Korean Wood Science and Technology
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• v.26 no.1
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• pp.97-105
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• 1998

This study examined the combined using effects of urea-formaldehyde (UF) resin and emulsifiable methylene diphyenyl diisocyanate (EMDI) resin to overcome performance limit of three-layer particleboards commonly made by UF resin. Two adhesive adding methods were applied with three types of resin combination system to each layer of particleboards. The one was simultaneously spreading method with emulsified compound resin (UF and EMDI) while the other was separately spreading method with unemulsified EMDI resin after UF resin spreading. The performance of particleboards bonded with 2% EMDI resin to the inner layers(IL) were similar to that of controls bonded with 8% UF resin. In the case of the emulsified compound resin application to the all layers of particleboards, there were marked reinforcing effects of EMDI resin, although a small amount of EMDI resin was mixed with UF resin. Especially bending MOR after 24 hours cold water-immersion and thickness swelling after 2 hours hot water-immersion of compound resin-bonded particleboards were remarkably different from those of pure UF resin-bonded particleboards. It was found that separately spreading method with unemulsified EMDI resin was more effective than simultaneously spreading method with emulsified compound resin to sustain the internal bond strength of particleboards after 24 hours cold water-immersion. In the resin combination systems to outer layers/inner layers of particleboards, water resistance and strength properties were superior in order of UF+EMDI/UF+EMDI > UF/UF+EMDI > UF/UF. And water resistance of particleboards was greatly dependent upon EMDI resin level in any adhesive adding method.

• Journal of the Korean Wood Science and Technology
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• v.35 no.1
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• pp.44-50
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• 2007

The objective of this study was to investigate the influence of the vehicle resin on the coating performance of Dan-Chung. The starch glue (F), fish glue (G), and aqueous acrylic resin emulsion (E) were used as vehicle resins. Panels coated with Dan-Chung were tested at accelerated weathering and outdoor conditions. Aqueous acrylic resin was proved as an excellent vehicle resin for Dan-Chung, because there was no flaking in Dan-Chung film after accelerated weathering and outdoor exposure. Discoloration of Dan-Chung using E was the smallest among the acceleratedly weathered panels. Adhesive property of Dan-Chung film using G was. remarkably improved by G-undercoating. On the contrary, G-undercoating lowered adhesive property of Dan-Chung film using E.

• Journal of the Korean Wood Science and Technology
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• v.33 no.1 s.129
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• pp.87-96
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• 2005

This study was carried out to evaluate the shear bond strength and adhesive bond durability of structural glued laminated timber (glulam) manufactured with mixed species lumber of Korean red pine, Korean pine and Japanese larch, using resorcinol adhesive and water-based polymeric-isocyanate adhesive (WPI). Each board used as a glulam lamina was graded by visual inspection. The visual lumber grade of the all species was very low due to the large size and number of knots and the steep slope of grain. In view of the results, appropriate pruning, sawing and drying processes might be needed to produce high grade lamina lumber with small knot size and drying defect free. Shear bond strength of every tested glulam specimen ranged between 7.9 and $9.9N/mm^2$, and much higher than the Korean Standard (KS) for glulam shear bond strength, $7.1N/mm^2$. There was not much shear bond strength difference between wood/resorcinol and wood/WPI. The resorcinol adhesive bond durability exceeded KS requirements. However, delamination on the end-grain surfaces of WPI glulam submerged in both room temperature and boiling water severely occurred, and its durability did not meet KS requirements. Further investigations may be required, and special care should be taken, to ensure long service life of WPI glulam used for exterior application. Results of this study are expected to be useful for improvement of mechanical properties and structural performance of mixed species glulam.

• Journal of the Korea Furniture Society
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• v.11 no.2
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• pp.7-12
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• 2000

This paper describes the bending strength properties of laminated woods which had three kinds of specimens according to finger length-12, 4.5 mm and butt joint and the acoustic emissions (AEs) generated during the test. 3-ply laminated wood beams were tension side layers (lower layers) composed of one middle lamina and two side-jointed laminae, with one butt joint ($_1BJ$), one finger joint (12mm, $_1FJ_{12}$) or one finger joint (4.5mm, $_1FJ_{4.5}$) in the middle lamina of tension side layer. And 3-ply laminated wood beams were tension side layers (lower layers) also composed of one lamina, with one butt joint (BJ), one finger joint (12mm, $FJ_{12}$) or one finger joint (4.5mm, $FJ_{4.5}$/) in tension side layer. Cryptomelia pieces were cut for butt and two finger types and glued with resorcinol-phenol resin adhesive. The results were as follows It was not effective in the bending modulus of elasicity (MOE) with IFJL type and had no difference from finger length. The bending modulus of rupture (MOR) of laminated wood beams including finger joint was the same values as that including butt feint and had no difference from finger length. It was effective in MOE with FJL type and had no difference from finger length. The effect of finger joint on MOR was much higher than that of butt joint but had no difference from finger length. The AE generation time of IFJL type was earlier than that of the control wood and the number of AE count was much more than that of the control wood. However, the AE generation time of FJL type was earlier than that of the control wood and the number of U count was much fewer than that of the control wood.

• Journal of the Korean Wood Science and Technology
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• v.51 no.1
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• pp.23-37
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• 2023

One type of biomass that has promising potential for bio pellet production is spent coffee grounds (SCGs). However, previous studies have shown that SCGs in bio pellets cause a lot of smoke. Therefore, they need to be mixed with a material that has a higher calorific value to produce better quality pellets. One material that can be used is pine wood because it has a natural resin content that can increase the calorific value. The aim of this study was to examine the quality of bio pellets produced with SCGs and pine wood charcoal at different particle sizes. The charcoal was ground using either a hammer mill (HM) or a ball mill (BM). Pine wood charcoal was mixed with SCGs at ratios of SCGs to pine wood charcoal of 4:6 and 6:4 by weight, respectively, and the adhesive used a tapioca with a composition ratio 5% of the raw material. The bio pellets were produced using a manual pellet press. The quality of the bio pellets was assessed based on Indonesian National Standard (SNI) 8021-2014, and the physical observations include flame length, burning rate, and compressive strength. The average water content, ash content, and calorific value of the bio pellets were in accordance with SNI 8021-2014, but the density and ash content values were below the standard values. The BM variation of bio pellets had a higher compressive strength than the HM variation, and the 4:6 BM variation had the longest burning time compared with 4:6 HM.

• Journal of the Korean Wood Science and Technology
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• v.45 no.4
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• pp.432-443
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• 2017

Maltodextrin and citric acid are two types of natural materials with the potential as an eco-friendly binder. Maltodextrin is a natural substance rich in hydroxyl groups and can form hydrogen bonds with lignoselulosic material, while citric acid is a polycarboxylic acid which can form an ester bond with a hydroxyl group at lignoselulosic material. The combination of maltodextrin and citric acid as a natural binder materials supposed to be increase the ester bonds formed within the particleboard. This research determined to investigate the bonding properties of a new adhesive composed of maltodextrin/citric acid for nipa frond particleboard. Maltodextrin and citric acid were dissolved in distillated water at the ratios of 100/0, 87.5/12.5, 75/25 and 0/100, and the concentration of the solution was adjusted to 50% for maltodextrin and 60% citric acid (wt%). This adhesive solution was sprayed onto the particles at 20% resin content based on the weight of oven dried particles. Particleboards with a size of $25{\times}25{\times}1cm$, a target density $800kg/m^3$ were prepared by hot-pressing at press temperatures of $180^{\circ}C$ or $200^{\circ}C$, a press time of 10 minute and board pressure 3.6 MPa. Physical and mechanical properties of particleboard were tested by a standard method (JIS A 5908). The results showed that added citric acid level in maltodextrin/citric acid composition and hot-pressing temperature had affected to the properties of particleboard. The optimum properties of the board were achieved at a pressing temperature of $180^{\circ}C$ and the addition of only 20% citric acid. The results also indicated that the peak intensity of C=O group increased and OH group decreased with the addition of citric acid and an increase in the pressing temperature, suggesting an interreaction between the hydroxyl groups from the lignocellulosic materials and carboxyl groups from citric acid to form the ester groups.

• Journal of the Korean Wood Science and Technology
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• v.45 no.1
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• pp.28-35
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• 2017

In this study, specimens of rigid frame joint were produced by integrating joints with adhesive and other specimens were produced by inserting a wooden gusset integrated with a column member into a slit-processed beam member and joining them with pins. Then the moment resistance performances of the specimens were examined. For the wooden gusset, a GFRP-reinforced wooden gusset was used. The calculation results of perfect elasto-plasticity for the frame specimens for which a GFRP-reinforced wooden gusset was inserted into and joined with the slit-processed beam member by pins were 20-80% lower compared to the control group which consisted of steel plate-inserted frame specimens. The rigid frame specimens for which the column and beam members have been integrated with adhesive showed almost no initial residual transformations, as well as 38% greater initial rigidity and 41% greater plasticity compared to the steel plate-inserted joint.

• Journal of the Korean Wood Science and Technology
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• v.35 no.5
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• pp.58-66
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• 2007

The objective of this research was to develop environment-friendly adhesives for face fancy veneer bonding of engineered flooring. Urea-formaldehyde (UF)-tannin and melamine-formaldehyde (MF)/PVAc hybrid resin were used to replace UF resin in the formaldehyde-based resin system in order to reduce formaldehyde and volatile organic compound (VOC) emissions from the adhesives used between plywoods and fancy veneers. Wattle tannin powder (5 wt%) was added to UF resin and PVAc (30 wt%) to MF resin. These adhesive systems showed better bonding than commercial UF resin with a similar level of wood penetration. The initial adhesion strength was sufficient to be maintained within the optimum initial tack range. The standard formaldehyde emission test (desiccator method) and VOC analyzer were used to determine the formaldehyde and VOC emissions from engineered flooring bonded with commercial UF resin, UF-tannin and MF/PVAc hybrid resin. By desiccator method, the formaldehyde emission level of UF resin showed the highest but was reduced by replacing with UF-tannin and MF/PVAc hybrid resin. MF/PVAc hybrid satisfied the $E_1$ grade (below $1.5mg/{\ell}$). VOC emission results by VOC analyzer were similar with the formaldehyde emission results. TVOC emission was in the following order: UF > UF-tannin > MF/PVAc hybrid resin.