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Physical Properties of Agro-Flour Filled Aliphatic Thermoplastic Polyester Bio-Composites
Eom, Young Geun,Kim, Hee Soo,Yang, Han Seung,Kim, Hyun Joong 한국목재공학회 2004 목재공학 Vol.32 No.3
The purpose of this study was to investigate the water absorption and thickness swelling of bio-composites at roon temperature. these properties of bio-composites mainly depend on the ability of the agro-flour to absorb water through hydrogen bonding between water and the hydroxyl groups of the holocellulose and lignin in the cell wall. As the content of agro-flour increased, the water absorption and thickness swelling of the bio-composites increased. The effect of agro-flour content and rice husk flour (RHF) particle size on the water absorption and thickness swelling of the bio-composites were evaluated. In general, wood-based materials showed significantly higher water absorption and thickness swelling than the bio-composites. this might be attributed to the ability of the polybutylene succinate (PBS) hydrophobic polymer to prohibit the water absorption and thickness swelling of the bio-composites. Therefore, the use of agro-flour filled (PBS) bio-composites, which exhibit improved dimensional stability in comparison with wood-based materials, is recommended.
Perforated Ray Cells in Korean Celastraceae and Oleaceae
( Young-geun Eom ),( Youn-jib Chung ) 한국목재공학회 1998 목재공학 Vol.26 No.2
Ray cells with perforations are recorded for the first time in the Korean Celastraceae species of Euonymus sieboldiana and Tripterygium regelii and the Oleaceae species of Abeliophyllum distichum,Forsythia ovata, Ligustntm japonicutn, and Osmanthus heterophylla. All these anomalous ray cells have simple perforations, and the vessel elements of all these species have simple perforation plates. Thus, in the Korean Celastraceae and Oleaceae, the perforations of ray cells appear to be identical with the types of perforation plates in the vessel elements of the same wood. The diagnostic value of the perforated ray cells is also discussed.
Eom, Young Geun,Yang, Han-Seung,Kim, Hyun-Joong 한국목재공학회 2003 목재공학 Vol.31 No.3
Shredded waste newspapers, waste acrylic raw fibers, and urea-formaldehyde (UF) adhesives, at 10% by weight on raw material, were used to produce recycled waste paper-waste acrylic raw fiber composite boards in laboratory scale experiments. The physical and mechanical properties of fire retardant treated recycled waste paper-waste acrylic raw fiber composite boards were examined to investigate the possibility of using the composites as internal finishing materials with specific gravities of 0.8 and 1.0, containing 5, 10, 20, and 30(wt.%) of waste acrylic raw fiber and 10, 15, 20 and 25(wt.%) of fire retardant (inorganic chemical, FR-7^(r)) using the fabricating method used by commercial fiberboard manufacturers. The bending modulus of rupture increased as board density increased, decreased as waste acrylic raw fiber content increased, and also decreased as the fire retardant content increased. Mechanical properties were a little inferior to medium density fiberboard (MDF) or hardboard (HB), but significantly superior to gypsum board (GB) and insulation board (IB). The incombustibility of the fire retardant treated composite board increased on increasing the fire retardant content. The study shows that there is a possibility that composites made of recycled waste paper and waste acrylic raw fiber can be use as fire retardant internal finishing materials.
부직포식 복합재(Nonwoven Web Composites)의 접착성능에 관한 전자현미경적 연구
윤형운,엄영근,김현중 國民大學校 山林科學硏究所 1999 山林科學 Vol.11 No.-
This study was carried out to investigate the effects of process variable and coupling agent(MAPP) on the adhesion characteristics of nonwoven web composites through scanning electron microscopy. Under the process conditions of 195℃ and 30㎏f/㎠ in hot-pressing temperature and pressure. 50% wood fiber and 50% polypropylene fiber on the basis of oven-dried weight, and target density of 0.7 g/㎤, the proper hot-pressing time appeared 3 minutes or longer because the polypropylene fibers in the core of composites were incompletely melted under 3 minutes. There was no significant difference in the melting extent of polypropylene fibers in the range of hot-pressing temperatures from 190℃ to 200℃. This might be attributed to the large amount and high melt flow index(MFI) of polypropylene fibers. As the addition level of polypropylene fibers to wood fibers or the melt flow index of polypropylene fibers increased, the application of relatively lower hot-pressing temperature and easier adjustment of composite thickness might be feasible in manufacturing composites. The excessively high hot-platen temperature, however, might produce the composites with decreased thickness or thickness variation because of rapid melting and flow of polypropylene fibers and might involve the risk of thermal degradation of wood fibers. Scanning electron microscopy revealed no effect of cooling time, in the range of 2 to 4 minutes, on adhesion characteristics in the composite made with 50% polypropylene fiber and 50% wood fiber. This might be attributed to the decreased internal stress which caused by the lower density level of 0.7 g/㎤ and complete melting of polypropylene fibers which added in the large amount of 50% on the basis of oven-dried weight. In the composites made with 10% polypropylene fiber and 90% wood fiber, the addition of coupling agent appeared to render the wood fibers more flexible and the adhesion between wood and polypropylene fibers better but the increased addition of coupling agent from 1 to 3% exerted little influence upon the adhesion characteristics. The addition of coupling agent, on the other hand, proved to have no effect on adhesion characteristics in the composites made with 50% polypropylene fiber and 50% wood fiber.