• Polymer(Korea)
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• v.39 no.1
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• pp.46-55
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• 2015

There is a limit for deforestation in order to keep the environmental cycle undisturbed. The heart of the paper is to replace the wood to a maximum extent to obtain a sustainable environment. This research aims at new natural composites in which treated hemp fiber used as reinforcement, synthetic cellulose used as particulate to improve the adhesion between matrix - fiber interface and Epoxy LY556 acted as matrix fabricated by hand layup technique. The density, water absorption, tensile properties, impact strength, hardness, flexural properties and compressive properties have been evaluated under ASTM standards and compare the results with existing materials such as wood, aluminium, etc., The composite hemp fiber reinforced polymer (HFRP) could be exploited as an effective replacement for wood and it would be suitable for automotive applications by comparing results.

• Journal of the Korean Wood Science and Technology
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• v.42 no.6
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• pp.691-699
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• 2014

In order to improve the dimensional stability and durability of wood, this study attempted to impregnate bismuth (Bi) - tin (Sn) alloy metal with low melting temperature into solid woods of three species such as radiata pine, red oak and white oak, and investigated to determine an optimum condition of manufacturing the metal alloy-wood composites with natural wood grains. These Bi-Sn alloys were chosen for this study because they were harmless to human and melting at low temperatures. The composites resulted in high dimensional stability and low thickness swelling, and also showed much improved performance such as high bending strength, high hardness, high electric conductivity, and high thermal conductivity as floor materials. A proper impregnating condition of all specimens was determined as 10 minutes of the preliminary vacuum time, and $185^{\circ}C$ of the heating temperature. The proper processing condition for radiata pine wood was 2.5 minutes of the pressuring time at the pressure of $10kgf/cm^2$. For red oak wood, 10 minutes of the pressuring time at the pressure of $30kgf/cm^2$ were the proper condition. The proper manufacture conditions for white oak wood was determined as 10 minutes of the pressuring time at the pressure of $50kgf/cm^2$.

• Journal of the Korea Furniture Society
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• v.26 no.4
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• pp.428-434
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• 2015

In this study, we received each wood plastic composites (WPC) from three manufacturers. These WPCs were evaluated regarding their physical and mechanical properties of both before and after accelerated weathering by ultraviolet (UV) irradiation. The total time of exposure of the WPCs to UV irradiation was 1800 h. The water absorption, volumetric swelling and shrinkage of WPCs did not affected by UV irradiation. Among the mechanical properties, there was no significant differences in bending strength and screw withdrawal resistance of UV treated WPCs compared with those of reference WPCs. However, surface hardness of WPCs showed decrease under UV irradiation. Stereoscopic microscopy observation revealed deterioration of the surface layer polymer in all weathered WPCs by UV. Exposure of the WPCs to UV irradiation caused decomposition and disappearance of the polymer layer. From this result, we can estimate that damage of polymer by UV led to a decrease in the surface hardness of the WPCs. The wood flours retained original shape after accelerated weathering by UV irradiation.

• Journal of the Korean Wood Science and Technology
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• v.34 no.2
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• pp.58-67
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• 2006

The relationship between acoustic property and coating hardness of musical instruments was investigated using a sound level meter and a pendulum hardness tester. Urethane topcoat, oil stain, natural oil varnish, and UV-curable epoxy acrylate coatings were applied on four different substrates: Paulownia coreana, Pinus koraiensis, Castanea crenata var. dulcis and Pinus densiflora. The influence of the coating type on the acoustic properties was stronger than that of the substrate. In the case of an oil stain formed with tacky coating layer, the sound pressure level (SPL) and surface hardness decreased with increasing of coating thickness. In the other coatings, SPL decreased and hardness increased as the coating layer thickened. However, SPL began to increase again at coating thickness above $100{\mu}m$.

• Journal of Korea Foresty Energy
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• v.18 no.2
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• pp.55-61
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• 1999

This study was carried out to investigate the influence of viscoelastic properties(or chemical composition) of a series of ethylen-viny1 acetate copolymers on impact noise and vibration damping of wood/polymer/wood sandwich composites. The impact noise and vibration damping of composites were very sensitive to the state of molecular motion of polymer. The noise and vibration damping of composites were maximum when the polymer was under the glass transition(vinylacetate 55~75%) at the test-temperature, and minimum rubbery state(vinyl-acetate 47~20%) or glassy state(vinylacetate 100~87%). The polymer under glass transition reduced the impact noise by 6~12 dB.

• Journal of the Korea Furniture Society
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• v.24 no.4
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• pp.379-388
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• 2013

In this study, the effect of various glass fiber (GF) contents in a shell layer and shell thickness changes on the flexural property of coextruded wood plastic composites (WPCs) in combination with three core systems (weak, moderate, and strong) was investigated. GF behaved as an effective reinforcement for the whole coextruded WPCs and GF alignments in the shell layer played an important role in determining the flexural property of the coextruded WPCs. At a given shell thickness, the flexural property of the whole coextruded WPCs was improved with the increase of GF content in shell. For core quality, when the core is weak, increase of GF content in shell led to improved flexural property of the whole composites and increase of shell thickness helped it. On the other hand, when the core is strong, the flexural property of the whole composites showed reduced features at low GF content in shell and increase of shell thickness aggravated it. This approach provides a method for optimizing performance of the coextruded WPCs with various combinations of core-shell structure and properties.

• Journal of the Korean Applied Science and Technology
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• v.25 no.1
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• pp.15-22
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• 2008

The effects of fillers on the mechanical and thermal properties of glass/novolac composites have been studied. The matrix polymer and reinforcement were novolac type phenolic resin and milled glass fiber, respectively. Three different fillers, such as calcium carbonate, aluminum oxide, and wood powder were used for glass fiber reinforced plastic(GFRP) manufacture. Gravity, moisture content, tensile and flexural strength were measured to analyze the mechanical properties of GFRP and the final composites was burned in the electronic furnace at $1000^{\circ}C$ to confirm thermal properties GFRP containing aluminium oxide shows the highest thermal stability with 32% of weight loss at $1000^{\circ}C$ for one hour. GFRP containing calcium carbonate shows the maximum flexural strength (146 MPa), but that containing wood powder dose the highest tensile strength (65 MPa). Conclusively, we found that the characteristics of final composites strongly depend on several factors, such as types of materials, contents and chemical affinity of fillers. Therefore, it is very important to set up the combination of fillers for GFRP manufacturing to improve both mechanical and thermal properties at the same time.

• Journal of the Korean Wood Science and Technology
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• v.41 no.2
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• pp.134-140
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• 2013

UV curing was introduced via a chemical treatment by adding small amounts of a hexafunctional acrylic monomer and a photoinitiator to improve the mechanical properties of PLA. This study also employed a semi-interpenetrated structured polymer network through the process of UV-curing. The UV curing behaviors were investigated using FTIR-ATR spectroscopy and gel fraction determination. Also, the tensile strength was investigated with different hexafunctional acrylic monomer contents and UV doses. The results showed that the crosslinking of UV-induced chemically treated PLA started at a low content of hexafunctional acrylic monomer, resulting in a significant improvement of the mechanical properties compared to those of neat PLA due to crosslinking.

• Journal of the Korean Wood Science and Technology
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• v.8 no.1
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• pp.1-12
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• 1980

경화촉진제로서 염화칼슘, 경화억제제로서 수크로오즈를 처리한 포트렌트시멘트의 양생효과를 전자현미경에 의해 관찰한 결과, 경화억제제를 처리한 시멘트는 결정을 이루지 못하고 융기상태로 남아있고, 경화촉진제를 처리한 시멘트는 겔형으로 변한후 육각형의 결정을 이루는 것이 관찰되었다. 또한 시멘트-목재 복합체의 양생은 좀 다른 양상을 보이고있어 경화제가 처리된 WCC는 포플러 스리버 표면에서 작은 융기가 겔상의 표면에 많이 관찰되나 무처리는 거의 일정한 모양의 입자가 관찰되어 시멘트 경화촉진제와 억제제의 효과를 구명하였다.

• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.238-242
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• 1998

Wood powder filled phenolic resin composites of different composition were prepared and their mechanical properties were investigated for optimum conditions. The composites showed maximum mechanical strength when the phenolic resin content was 45 wt%. Polyurethane prepolymer(PU) was evaluated as a modifier of the phenolic resin composites. Blocking of the isocyanates in the PU with phenol was necessary for homogeneous mixing of raw materials for the components. Maximum mechanical strength of the PU modified composites was observed when the PU content was 5 wt%. It was found that the mechanical strength of the composites cured at $210^{\circ}C$ were higher than those of the composites cured at $150^{\circ}C$.