• Journal of the Korean Wood Science and Technology
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• v.13 no.3
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• pp.3-26
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• 1985

The object of this study was to investigate the effects on physical and mechanical properties of wood particle and sawdust board combined with wire net. Conventional forming, press-lam, and veneer comply boards combining one to four wire net sheets were made from wood particle and sawdust with different spacings (8, 10, 12, and 18 Mok) and different wire diameters (0.35, 0.50, and 0.80mm) composing wire net. They were compared and analyzed statistically with specific gravity, thickness swelling, length swelling, bending properties (modulus of rupture, modulus of elasticity, work to proportional limit, and total work), internal bonding strength, and screw holding strength between wood particle and sawdust boards. The results obtained at this study as cording to the discussions might be concluded as follows; 1. In specific gravity, both particle and sawdust boards by press-lam method were higher than by conventional forming and veneer comply method, and the boards containing more wire net sheets also showed higher value. But the wire net spacings(Mok) had no influence on specific gravity. In general, particle board showed higher specific gravity than sawdust board. Veneer comply board showed lowest specific gravity values. 2. Both particle and sawdust boards by press-lam method was slightly lower than by conventional forming and veneer comply method in thickness swelling. The sawdust board containing 8, 12. and 18 Mok wire net showed lower thickness swelling than the corresponding particle board, but both sawdust and particle boards containing the T8 and 10 Mok wire net showed higher and similar thickness swelling. 3. Both particle and sawdust boards containing wire net showed no difference in MOR and MOE of bending. Comply board was the highest and particle board showed slightly higher than sawdust board in MOR and MOE values. 4. In work to proportional limit and total work in bending, both particle and sawdust boards containing thicker wire diameter and more wire net sheets showed higher value. From these facts, it is conceivable that boards with thicker wire diameter and more wire net sheets show increasing resistance against external force. But there was no significant difference between particle and sawdust borads. 5. In resistance against delamination (internal bonding strength), both sawdust and particle boards containing wire net showed lower value than control, and also showed decreasing tendency with more number of wire net sheet composed. Particle board showed higher resistance against delamination than sawdust board. 6. In screw holding strength, sawdust board containing thicker wire diameter and more wire net sheets showed higher value, but particle board by press-lam method was higher than by conventional forming and veneer comply method. Screw holding strength of particle board was higher than that of sawdust board.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.1
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• pp.120-127
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• 2006

The hammer-milled characteristics of waste wood materials such as lumber, plywood, particleboard(PB), MDF and railroad tic were investigated in this study. The physical and mechanical properties of recycled boards according to types of recycled particle and the mixing ratios were also studied. The hammer-milled, waste wood materials had the dimensional distributions suitable for the core layer panicle. Bending strengths of recycled boards (one layer) were shown in order of plywood, PB(laboratory-fabricated with particles used in the PB factory), lumber, tego film-overlaid plywood, MDF, waste railroad tie, PB(factory-made) and LPL-overlaid PB. Cured resin and creosote containing waste wood contributed to dimensional stability of reconstituted boards. Considering the mixing effects between lumber and plywood with recycled PB particle, lumber particle was contributive to bending strength, MOE and internal bond(IB) strength, whereas plywood particle was contributive to dimensional stability. The bending and IB strength of 3 layer boards composing only recycled waste wood particles in core layer of board were in order of lumber, plywood, PB and MDF. On the other hand, the thickness swelling was in order of PB, lumber, plywood and MDF. Bending strength of the 3 layer boards mixed with recycled PB-particle in the core layer had a decreasing tendency, as the mixing ratios of recycled PB-particles increased. The dimensional stability of 3 layer recycled board was improved as the mixing ratio of recycled PB-particle increased same as in one layer. Formaldehyde emission of boards fabricated with recycled PB-particles in the core layer of the PB was in the range of E2 grade (below 5.0mg/l).

• Journal of Environmental Science International
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• v.24 no.2
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• pp.245-251
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• 2015

The main objective of this study is to recovery valuable metals with metal particle size distributions in waste cell phone PCBs(Printed Circuit Boards) by means of pulverization and nitric acid process. The particle size classifier also was evaluated by specific metal contents. The PCBs were pulverized by a fine pulverizer. The particle sizes were classified by 5 different sizes which were PcS1(0.2 mm below), PcS2(0.20~0.51 mm), PcS3(0.51~1.09 mm), PcS4(1.09~2.00 mm) and PcS5(2.00 mm above). Non-magnetic metals in the grinding particles were separated by a hand magnetic. And then, Cu, Co and Ni were separated by 3M nitric acid. Particle diameter of PCBs were 0.388~0.402 mm after the fine pulverizer. The sorting coefficient were 0.403~0.481. The highest metal content in PcS1. And the bigger particle diameter, the lower the valuable metals exist. The recovery rate of the valuable metals increases in smaller particle diameter with same leaching conditions. For further work, it could improve to recovery of the valuable metals effectively by means of individual treatment, multistage leaching and different leaching solvents.

• Journal of the Korean Wood Science and Technology
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• v.22 no.1
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• pp.54-65
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• 1994

This research carried out to investigate the effects of inorganic materials in paper sludge on the thermal degradation and of paper sludge addition on physical and mechanical properties of paper sludge-wood particle mixed boards in comparison with unmodified particleboards. Also these unmodified particleboards and paper sludge-wood particle mixed boards were soaked in aqueous solutions of fire-retardant chemicals(diammonium phosphate and zinc chloride), and their fire retardancy were tested by oxygen index method and ISO ignition test to determine the feasibility of paper sludge, industrial waste, as a recyclable resource in fabrication of fire-resisting panels for building material. Since the redrying of fire-retardant treated particleboards and paper sludge-wood particle mixed boards were made by press drying method, this process was a simple and effective method. On the other hand, flexural bending strength and internal bonding strength were also analysed to evaluate mechanical properties through standard method.

• Journal of the Korean Wood Science and Technology
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• v.43 no.3
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• pp.364-373
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• 2015

This study was carried out to estimate the effects of density and mixing ratio of mandarin peels on the bending performances of the sawdust-mandarin peels particle boards. The board density influenced significantly to the bending performance of boards. Dynamic modulus of elasticity (dMOE) and static modulus of elasticity (sMOE) and modulus of rupture (MOR) of particle boards decreased with an increase in the mixing ratio of mandarin peels at the board densities of $0.4g/cm^3$ and $0.5g/cm^3$. High correlations were found between the dMOE and sMOE, and dMOE and MOR of particle boards prepared. Therefore, it was concluded that the dMOE obtained by free vibration test using resonance frequency could be used for predicting the sMOE and MOR of sawdust-mandarin peels particle boards.

• Journal of the Korea Furniture Society
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• v.10 no.1
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• pp.95-102
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• 1999

The objective of this paper was the development of boards made from waste newspapers. The boards were produced from particle ONP(old newspaper) to reduce energy consumption in the board production process. ONP boards bonded with polyurethan adhesives(PU) were produced on a laboratory scale, and their physical and mechanical properties were examined. The average density of the ONP was $0.48g/cm^3$, and the densities of the boards were $0.50-0.90g/cm^3$. Therefore, th compaction ratios of the boards were in the range of 1.04-1.88. The results obtained were as follows: 1) An increase in board density results in a corresponding improvement in bending properties. 2) An increase in board density results in increased thermal conductivity. 3) In this research, ONP board can be used only for interior applications. To gain exrerior applications, the dimensional stability properties(thickness swelling and water absorption) need to be improved.

• Journal of the Korean Wood Science and Technology
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• v.42 no.2
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• pp.130-137
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• 2014

Nondestructive evaluation (NDE) method by using a resonance frequency mode was carried out for ceramics made from particle boards with different phenol resin impregnation ratios (30, 40, 50, 60%) at carbonizing temperature of $800^{\circ}C$. The material for ceramics was Miscanthus sinensis var. purpurascens board. Dynamic modulus of elasticity increased with increasing impregnation ratio. There was a close relationship of dynamic modulus of elasticity and static bending modulus of elasticity to modulus of rupture (MOR). However, the result indicated that correlation coefficient is higher in dynamic modulus of elasticity to MOR than that in static modulus of elasticity to MOR. Therefore, the dynamic modulus of elasticity using resonance frequency by free vibration mode is more useful as a nondestructive evaluation method for predicting the MOR of ceramics made from Miscanthus sinensis var. purpurascens particle boards by different phenol resin impregnation ratios.

• Journal of the Korea Furniture Society
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• v.14 no.2
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• pp.31-38
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• 2003

This study was carried out to investigate characteristics of wood-based panels and wood-cement board for the possible uses as flooring and wall materials. The optimum cement/wood ratio(C/W ratio) of wood~cement board manufactured by clamp-pressing was from 2.7 to 3.2. The dimesional stability was superior in the C/W ratio of 3.2. Particularly, the dimensional stability of cement board using fine particle for particleboard face layer was favorable through three levels of C/W ratio. According to types of wooden material, bending strength of cement board using coarse particle for particleboard core layer or old newspaper(ONP) fiber was relatively higher than others. Thermal conductivities of wood-cement boards were no lower than that of gypsum board, and higher than those of plywood and boards. In case of wood-cement board of the C/W ratio of 2.7, the fire-proof performances of cement composite boards were greater than that of gypsum board, and weight loss reached to about a half of gypsum board. Then, wood-cement boards showed superior fire-proof performance compared to wood-based panels.

• Journal of the Korean Wood Science and Technology
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• v.21 no.2
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• pp.57-65
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• 1993

The aim of this research was to manufacture sludge-particle board using paper sludge with wood particle and to investigate physical and mechanical properties of various sludge-particle boards, fabricated with ratios of sludge to particle of 10 to 90, 20 to 80, 30 to 70, 40 to 60 and 50 to 50(oven dry weight based). Sludge-particle boards were manufactured by urea-formaldehyde resin, 0.8 target specific gravity, and 10mm thickness. It was possible to manufacture sludge-particle board as the same processing in the present particleboard manufacturing system. This sludge-particle board have different properties as composition ratios of sludge and particle. And sludge-particle board made from 10 percent to 20 percent of sludge mixing ratio have similar mechanical properties compared with control particleboard. Especially, the sludge-particle board made from 10 percent to 40 percent mixing ratios of sludge have superior to control particleboard in internal bond, screw withdrawal holding strength and modulus of elasticity. In the case of dimensional stability, water absorption was increased and thickness swelling was decreased as increased with sludge mixing proportion. The sludge-particle board made of different mixing ratios of our laboratory design was able to concluded that there is possibility of partial substitution of wood particle materials.

• Journal of the Korean Wood Science and Technology
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• v.4 no.1
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• pp.33-37
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• 1976

This experiment was carried out to study the effects affecting to particle board quality by the mixed use of sawdust abandoning as the sawmill residues. The obtained results at this study are summarized as follows: 1) There was no significance in bending strength between 5% sawdust addition and non mixed particleboard. 2) The water absorption was increased as accordance with adding more sawdust. When the boards were mixed with sawdust until 20% the differences were shown among the test boards. 3) There was no differences between the moisture contents and also specific gravities between the comparated boards. There was no difference between the boards mixed with 5% sawdust and non mixed boards.