| Summary: | 碩士 === 國立宜蘭大學 === 森林暨自然資源學系碩士班 === 107 === Heat treatment of wood is a process that can increase the dimension durability and the resistance of biological degradation of wood. In order to study the effect of different heat treatment conditions on the properties of wood composites, plywood, medium density fiberboard (MDF) and oriented strand board (OSB) were chosen as test materials. Four temperatures, 150℃,170℃, 190℃, 210℃, and three process time, 1 hour, 2 hours and 3 hours, were applied for heat treatment process. The properties for each test group will be evaluated to determine the appropriate thermal modification conditions for different composite materials. Test results shown that the mass loss of wood composites increases while the heat modified temperatures and times increased, and the mass loss was significant if the treated temperatures were higher than 190°C. The moisture absorption expansion rate of the OSB was below 2% if the treated temperatures were higher than 210℃,while the MDF was below 15% at same process conditions. The percentage of immersion delamination test is 100% passed for the radiata pine plywood and birch plywood by glued with phenol formaldehyde resin, while it was 80% for the lauan plywood with urea formaldehyde resin . On the surface properties test, the color of the test samples became darker with treated temperatures and times increased. The change of L* value is significant than that of a* and b*, this indicated that the test material is darker after heat treatment. The most significant of ΔE*was observed in the birch plywood samples. There was no significant change on the modulus of elasticity, but a slight increase in the plywood specimens treated at 150°C. The bio-resistant performance was examined in the six-week termite test, and there was no significant change observed among each sample group.
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