• Journal of the Korean Wood Science and Technology
• /
• v.51 no.1
• /
• pp.14-22
• /
• 2023

Economical use of larix (larch) boards (grade 3) in industries is lower than that of imported hardwood; thus, studies have been conducted toward performance improvement of larix boards. Herein, flexural modulus of larix board samples laminated with wood adhesives polyurethane resins, poly (vinyl acetate) resins, phenol-resorcinol-formaldehyde resins, melamine-formaldehyde resins, and urea-formaldehyde resins was compared with that of the samples bonded with adhesives reinforced with mesh-type basalt fibers. Moreover, the flexural moduli of the laminated samples bonded by mesh-type basalt fibers were compared with those of reinforced samples. The results showed that boards laminated with polyurethane and urea-formaldehyde resin adhesives had higher flexural modulus than those without the lamination. In particular, the increase in the flexural modulus was relatively significant for the 2- and 3-ply board structures laminated with polyurethane adhesives compared to those with reinforcement. The 3-ply board structure without reinforcement had the highest flexural modulus when the urea-formaldehyde resin adhesive was used.

• Fire Science and Engineering
• /
• v.15 no.3
• /
• pp.7-13
• /
• 2001

In this paper, we had analyzed comsbustion gases according to pyrolysis $600^{\circ}c$, $800^{\circ}c$ and $1000^{\circ}c$ for polymeric material using a GASTEC colorimetric gas detector tube in order to combustion gases toxicity evaluation for flame retardant untreated ply wood, flame retardant treated ply wood, flexible polyvinyl chloride and flexible polyurethane foam of polymeric material. As a result, comsbustion gases producted from small specimens of polymeric material had reached fatal to man at a 30 minute exposure time that had possesed toxicity index. Toxicity index at pyrolysis $800^{\circ}c$ of flexible polyvinyl chloride was 31.74. Flexible polyvinyl chloride was the highest toxicity index of flame retardant untreated ply wood, flame retardant treated ply wood, flexible polyvinyl chloride and flexible polyurethane foam. The comsbustion gases producted commonly no concern with pyrolysis temperature had analyzed carbon dioxide($CO_2$) and carbon monoxide(CO). Toxicity index had investigated differently according to pyrolysis temperature even a similar materal.

• Journal of the Korean Wood Science and Technology
• /
• v.24 no.4
• /
• pp.15-21
• /
• 1996

This study was carried out to investigate the making method and properties of Hanji(Korean traditional paper) for wallpaper for the purpose of mass production and mass consumption of Hanji. Paper mulberry fiber was longer than wood fiber in length and it had also much extractives and ash in content. Bast fiber was a little damaged in the fibrilation and beating process because it was weak in flexibility and compressive properties. Proper conditions for making two-ply and three-ply Hanji were examined and six kinds of Hanji were made on the basis of the three-ply paper making method. The sample OH(Original Hanji) 2-2 and OH 3-2 among them obtained good results in quality test by appearance from wallpaper makers.

• Journal of the Korean Wood Science and Technology
• /
• v.35 no.6
• /
• pp.108-117
• /
• 2007

This research was performed to investigate the feasibility of bamboo as a raw material for the manufacture of plywood. Wood veneer-bamboo zephyr composite boards (WBCB) were manufactured using keruing (Dipterocarpus sp.) veneers and hachiku bamboo (Phyllostacbys nigra var. henonis Stapf) using various adhesives, and the effect of the method and amount of resin spread on the mechanical properties of the composites were investigated. The WBCB manufactured using polymeric isocyanate (PMDI) showed the best mechanical properties, followed by phenol-formaldehyde resin (PF), phenol-melamine-formaldehyde resin, urea-melamine-formaldehyde resin, and urea-formaldehyde resin. However, considering the operation feasibility as well as mechanical properties, PF resin proved to be the appropriate adhesive for the practical purpose. As the amount of resin spread increased, the mechanical properties of 5-ply WBCB with 12 mm thicknesses manufactured using PF resin tended to increase, and more failure occurred at the interface between veneer and bamboo zephyr than at the interface among bamboo zephyrs. This result suggests that penetration of resin into bamboo zephyr could be the important factor. In this research, the appropriate amount of resin amount was $320g/m^2$. 5-ply WBCBs were manufactured using various methods of resin spread but the effect of the methods on the mechanical properties showed no little difference, which meant that the method of resin spread could be chosen considering the manufacturing conditions and operation feasibility.

• Journal of the Korea Furniture Society
• /
• v.11 no.2
• /
• pp.7-12
• /
• 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
• /
• v.49 no.6
• /
• pp.574-590
• /
• 2021

International efforts to prevent illegally logged wood are expanding around the world. The "Legal Wood Trade Promotion System" was enacted in Korea in 2019 to strengthen the legal import and distribution of commercial wood in Korea. Since then, this system has promoted and ensured that the imported wood and wood products are legal with respect to the country of origin, wood species, and harvested area. As verification methods, DNA analysis technology and anatomical analysis using a microscope are mainly used in conjunction. Therefore, in this study, wood species of plywood were identified by analyzing the anatomical characteristics of various wood products for the first time. Douglas fir (Pseudotsuga menziesii (Mirb.) Franco.) and larch (Larix kaempferi (Lamb.) Carriere) plywoods (7, 9 ply) were obtained from four companies that supply plywood in Korea. After cutting each company's plywood to a size of about 1 cm³, the layers from top to bottom were separated into single layers, and three sections were observed using an optical microscope. The results revealed that the plywood was composed of a mixture of softwood and hardwood wood species, pine wood species, poplar wood species, or a mixture of larch and pine wood species. Identification of wood species using microscopy is important and can enable the scientific analysis and verification of various wood products, including plywood, imported from countries where the likelihood of indiscriminate distribution of illegal wood and illegal logging is high.

• Journal of the Korean Wood Science and Technology
• /
• v.40 no.4
• /
• pp.287-293
• /
• 2012

This study was carried out in order to compare nail shear strength between domestic plywood and imported OSB for structural sheathing members as infill wall of wooden construction. The differences of nail shear strength between parallel-to-grain direction and perpendicular-to-grain direction of sheathing material to frame material were distinct at the plywood composition. The shear strengths of plywood and OSB with nail met current design values. The plywood of P-4 type, which uses MLH at surface layer and constructs 7 ply, showed greater than OSB regardless of grain direction of sheathing material to frame material. When the plywood as sheathing material to frame material was used, it was found out that the overall construction of perpendicular-to-grain direction of plywood had greater nail shear strengths than the construction of parallel-to-grain.

• Journal of the Korean Wood Science and Technology
• /
• v.41 no.1
• /
• pp.33-41
• /
• 2013

This study was performed to analyse cause of quality deterioration using byproduct of plywood and to determine physical and mechanical properties of particleboard used new bonding condition we found. The result of bending strength of Com-Ply board using EMDI is 57.7 $N/mm^2$ on linear direction and 25.1 $N/mm^2$ on vertical direction. EMDI has better water-resisting qualities than Urea formaldehyde adhesive according to result of thickness swelling and water absorption test. Pre-treatment soaked particle 72 hours in water caused increase of HCHO emission.

• Journal of the Korean Wood Science and Technology
• /
• v.49 no.2
• /
• pp.107-121
• /
• 2021

The purpose of this study is to optimize the bonding method of the plywood suitable for cross-laminated timber (CLT) with plywood as a core by analyzing the flexural performance and failure mode according to the lamina species, the method of bonding plywood in the longitudinal direction, and whether or not adhesive is applied to the joint. In the case of the Douglas fir lamina layer, the modulus of elasticity decreased by about 11.5% due to longitudinal bonding, and the modulus of rupture increased or decreased according to the adhesive application and bonding method. The optimal conditions were derived as the butt joint without adhesive, half lap joint with adhesive, and butt joint. In the case of the larch lamina layer, the modulus of rupture and the modulus of elasticity decreased by about 15% and 40%, respectively. When using the half lab joint and tongue & groove joint, it is believed that it reduces the load transmitted to the middle layer by primarily preventing the failure on flexure at the joint of the plywood layer. From the results of this study, the larch lamina layer used in the manufacturing process of Ply-lam CLT did not show any difference based on the bonding method. Butt joint and half lap joint bonding method are determined to be suitable when using Douglas fir lamina layer.

• Journal of the Korean Wood Science and Technology
• /
• v.41 no.5
• /
• pp.425-431
• /
• 2013

Estimation equations of shear modulus in the plane of laminated veneer lumber (LVL) were compared each other through uniaxial tension test results. The equations - basic elastic equation in the dimensional orthotropic case, Hankinson's formula and empirical equation proposed by Salikis and Falk, were applied to determine the elastic constants at various angles to the grain, which were needed for determination of shear modulus. Tensile elastic modulus of LVL predicted from these equations were compared with test data to evaluate the accuracy of the equation. Tensile elastic modulus rapidly decreased at orientations between 0 and 15 degrees and elastic modulus at grain angles of 15, 30, and 45 degrees overestimated in the presented equations. But the proposed equation by Salikis and Falk showed better prediction, especially at 30, and 45 degrees. This proposed formula would be more useful and practical for estimating of shear modulus of wood composites like LVL to minimize the effect of Poisson's ratio term.