• Journal of the Korean Wood Science and Technology
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• v.47 no.3
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• pp.336-343
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• 2019

Effects of a novel mold inhibitor specifically for bamboo, on the properties of composite products have been confirmed in this study. The mechanical and dimensional stability properties of bamboo fiber-based composites (BFBCs) from different bamboo species were also investigated. The results showed that Burmanica Gamble possessed the highest values of modulus of elasticity (MOE) of 33.2 GPa, modulus of rupture (MOR) of 286.9 MPa, compressive strength of 182.6 MPa and shear strength of 24.0 MPa. By contrast, Phyllostochys heterocycla among all of species showed the lowest MOE of 16.3 GPa, MOR of 170.3 MPa and compressive strength of 128.9 MPa were the lowest among all of species. Moreover, there is a remarkable variation in the swelling and water absorption between the samples with 4 h and 28 h water immersion treatment, especially Phyllostachys iridenscens. Overall, the results suggested that TCIT (Tebuconazole and 3(2H)-isothiazolone) had no significant effect on the mechanical properties compared with the control condition, and it would be utilized as an antimould of BFBCs manufacturing.

• Journal of Forest and Environmental Science
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• v.36 no.3
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• pp.219-224
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• 2020

Urea formaldehyde resins are widely used in the manufacturing of wood composite and their usage is always combined with release of formaldehyde characterized to be hazardous to health during and after the manufacturing of the products. This study investigates the effectiveness of wood-based adhesive from oil of pyrolysed Triplochiton scleroxylon sawdust for the production of composite board. The wood-derived Pyrolytic Oil (PyO) was blended with Urea Formaldehyde (UF) resin to formed Pyrolytic Oil-Urea Formaldehyde (PyOUF). The obtained PyOUF called Wood-Based Adhesives at four blends and control (UF) viz; 1:1, 1:2, 1:3, 2:1, 1:3 were further employed to prepare the composite board and test for their bonding strength by physical (water absorption-WA and thickness swelling-Th.S) and mechanical properties (modulus of elasticity-MOE, modulus of rupture-MOR, and impact bending-IB). Data obtained was analysed using analysis of variance at α 0.05. The result of analysis of variance conducted on physical properties show significant difference (p≤0.05) between the WA values obtained when testing the different blending proportion of PyOUF and likewise between 2 and 24 h of immersion. PyOUF had significant effect (p≤0.05) on Th. S for 24 h but no significant different (p>0.05) for the 2 h period of soaking. The analysis of variance on mechanical properties of the composite board (MOE, MOR, and IB) show significance differences (p≤0.05) between the strength values obtained when testing the different ratios of PyO with UF. PyO content influenced the properties of the boards and it is evident that PyO can be used in the manufacture of composite board.

• Journal of the Korean Wood Science and Technology
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• v.29 no.3
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• pp.36-46
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• 2001

This study was to find a way of reusing wood and plastic wastes, which considered as a troublesome problem to be solved in this age of mass production and consumption, in manufacturing wood fiber-polypropylene fiber composite panel. And the feasibility of this composite panel as a substitute for existing headliner base panel of automobile was also discussed, especially based on physical and mechanical performance. Nonwoven web composite panels were made from wood fiber and polypropylene fiber formulations of 50 : 50, 60 : 40, and 70 : 30, based on oven-dry weight, with densities of 0.4, 0.5, 0.6, and 0.7 g/$cm^3$. At the same density levels, control fiberboards were also manufactured for performance comparison with the composite panels. Their physical and mechanical properties were tested according to ASTM D 1037-93. To elucidate thickness swelling mechanism of composite panel through the observation of morphological change of internal structures, the specimens before and after thickness swelling test by 24-hour immersion in water were used in scanning electron microscopy. Test results in this study showed that nonwoven web composite panel from wood fibers and polypropylene fibers had superior physical and mechanical properties to control fiberboard. In the physical properties of composite panel, dimensional stability improved as the content of polypropylene fiber increased, and the formulation of wood fiber and polypropylene fiber was considered to be a significant factor in the physical properties. Water absorption decreased but thickness swelling slightly increased with the increase of panel density. In the mechanical properties of composite panel, the bending modulus of rupture (MOR) and modulus of elasticity (MOE) appeared to improve with the increase of panel density under all the tested conditions of dry, heated, and wet. The formulation of wood fiber and polypropylene fiber was considered not to be a significant factor in the mechanical properties. All the bending MOR values under the dry, heated, and wet conditions met the requirements in the existing headliner base panel of resin felt.

• Journal of the Korean Wood Science and Technology
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• v.46 no.4
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• pp.355-361
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• 2018

In this study, the dimensional stability and mechanical properties of bamboo fiber-based composites (BFBCs) were studied at two pressing manufacturing processes, i.e., hot- and cold- pressing, and were compared with three density parameters (1.0, 1.1, and $1.2kg/m^3$). Width swelling ratio (WSR), thickness swelling ratio (TSR), and water absorption ratio (WAR) were calculated for water immersions of 4 and 28 h. WSR, TSR, and WAR for specimens immersed for 28 h were higher than those for 4 h treatment, which shows that the immersion time has a significant influence on the dimensional stabilities of BFBCs. Moreover, the positive linear relations between density and dimensional were observed at both the pressing ways, indicating that the WSR, TSR, and WAR decreased with an increase in the density of BFBCs. The compressive strength, shear strength, modulus of rupture (MOR), and modulus of elasticity (MOE) were determined. The compressive strength, MOR, and MOE of hot-pressed specimens were significantly higher than those for the cold-pressed specimens, which are also directly proportional to density. Moreover, the samples with the highest density of $1.2kg/m^3$ performed high values on mechanical properties in both the manufacturing methods.

• 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.43 no.4
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• pp.429-437
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• 2015

It has been known that acetylation improves the dimensional stability of wood. Liquid phase acetylation is more popular than gas-phase acetylation for the effectiveness of weight gain of wood. In this study domestic red and Korean pine specimens were liquid phase acetylated and their physical properties, such as density, bending strength, dimensional stability etc., were investigated. Acetylation increased the average weights of red and Korean pine specimens by 10.4% and 9.2%, respectively, and their average oven-dry densities were increased by 6.9% and 4.6%, respectively. Acetylation did not influence on modulus of rupture (MOR), modulus of elasticity (MOE) and dynamic MOE (DMOE). The average percentage reduction in hygroscopicity (PRH) of red and Korean pine specimens were respectively 20.6% and 13.8%, while the average percentage reduction in water soaking (PRW) were respectively 20.0% and 8.5%. Thus it can be concluded that the liquid acetylation improved the dimensional stability of red pine specimens more than that of Korean pine specimens.

• Journal of Forest and Environmental Science
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• v.39 no.1
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• pp.27-39
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• 2023

Twenty-five Eucalyptus clones (14 E. camaldulensis - EC and 11 interspecific eucalypt hybrid clones - EH) grown in three contrasting sites were evaluated for the growth and few wood traits at 4 years of age. The stability, genotype-site interaction and suitability of these clones for pulp and solid wood industry sectors were studied. Growth of eucalypt clones was significantly higher at site 1 with higher rainfall, but wood density did not differ significantly from lower rainfall sites. Kraft pulp yield (KPY) decreased from sites 1 to 3 based on moisture availability, but not between two groups of clones. Volumetric shrinkage (VS) was significantly higher in EC clones at site 3 with lowest rainfall, but there was no specific trend at other two sites with maximum (site 1) and intermediate (site 2) rainfall. The mechanical traits modulus of rupture (MOR) and modulus of elasticity (MOE) were at par in sites 1 and 2, but significantly lower at the driest site 3. The growth rate had a significant positive correlation with KPY, MOR and MOE and a negative correlation with VS, but no significant impact on wood density in both groups of clones. Genotype×environment interaction (G×E) was evident in most traits due to the difference in response of clones to moisture availability. Since wood density was negatively correlated to KPY, it has to be kept at an optimum level for the profitability of pulp industry. There was no significant difference between EC and EH clones for most traits except VS at site 3. Stability of clones varied across sites in different traits, and hence clones may be selected for deployment at each site by screening for growth, followed by wood density, considering the relationship of growth and density with other traits required by pulp and solid wood industry sectors.

• Journal of agriculture & life science
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• v.45 no.6
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• pp.41-46
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• 2011

In this study, in addition to the green tea-wood fiber hybrid composite boards of previous researches, to make effective use of saw dust of domestic cypress tree with functionalities and application as interior materials, eco-friendly hybrid composite boards were manufactured from wood fiber, green tea and saw dust of cypress tree. We investigated the effect of the component ratio of saw dust and green tea on static bending strength performances. Static bending MOE (modulus of elasticity) was within 0.956~1.18GPa, and showed the highest value in wood fiber : green tea : saw dust = 50 : 40 : 10 of the component ratio, and had the lowest value in 50 : 30 : 20 of component ratio. These values were 2.0~3.1times lower than those of green tea-wood fiber hybrid composite boards reported in the previous researches. The bending MOR (modulus of rupture) showed 8.99~11.5MPa, the change of the bending MOR with component ratio of the factors was the same as that of bending MOE. These values had 1.9~3.5 times lower value than those of green tea-wood fiber hybrid composite boards, and showed the slightly lower values than the MOR of particle boards (PB) and medium density fiberboards (MDF) prescribed in Korean Industrial Standard. Therefore, it is considered that these hybrid composite boards need to improve strength performances by component ratio change, hybrid composite with other materials and adhesive change etc. in order to industrialize the hybrid composite boards.

• Journal of agriculture & life science
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• v.44 no.5
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• pp.1-8
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• 2010

In this study, eco-friendly hybrid composite boards were manufactured from green tea and wood fibers for application as interior materials with various functionalities of green tea and strong strength properties of wood fibers. In this relation, the effect of green tea content on the static bending strength performances of these green tea and wood fibers composite boards were investigated. Static bending strengths of hybrid composite boards were lower than those of control boards and decreased with the increase of green tea content. Also, the strength performances appeared to be somewhat different by resin type used for board manufacture. The hybrid composite boards manufactured from $E_1$ grade urea resin adhesive, which has higher molar ratio of formaldehyde to urea than that of $E_0$ grade one, were 1.08~1.53 times higher in bending modulus of elasticity (MOE) and 1.19~1.82 higher in modulus of rupture (MOR) than that manufactured from $E_0$ grade. And, the differences of MOE and MOR between hybrid composite boards manufactured from $E_0$ grade and $E_0$ grade urea resin adhesive increased with the increase of green tea content. In the case of hybrid composite boards manufactured from $E_1$ grade urea resin adhesive, the MOR was within 0.94~1.03 times the commercial medium density fiberboard. Thus, it was thought that eco-friendly hybrid composite boards with various functionalities and strong strength performances could be manufactured from green tea and wood fibers.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.644-647
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• 2004

Modulus of rupture (MOR) and flexural toughness in hybrid fiber reinforced cement pastes mixed with micro-fiber (carbon fiber) and macro-fiber (steel fiber) and replaced with silica fume according to the fixed ratio were researched. Reinforcing efficiency in specimens were estimated by two factors, such as strengthening factor $(F_s)$ and toughening factor $(F_t)$, which were calculated from the analysis of variance (ANOVA) of the response values, such as MOR and absorbtion energy $(W_0)$. According to the experimental design by the fractional orthogonal array, nine hybrid fibrous reinforced paste series and one non-reinforced control paste were manufactured. Specimens of each series were tested by the INSTRON Inc. 8502(model) equipment in three-points bending and then measured the load-deflection response relationships. Considerable strengthening of cement pastes resulted in' the case of other factors without carbon fiber and toughening of cement pastes about all factors showed high. Based on the significance of factors related to response values from ANOVA, following assessments were available; $F_s$ or MOR: silica fume $\gg$ steel fiber $\gg$ carbon fiber; $F_t\;or\;W_0$: steel fiber > carbon fiber > silica fume. Optimized composition condition was estimated by steel fiber of $1.5\%$, carbon fiber of $0.5\%$ and silica fume $7.5\%$ in side of strengthening and steel fiber of $1.5\%$, carbon fiber of $0.75\%$ and silica fume $7.5\%$ in side of toughening.