Effects of Target Density and Strand Size on Properties of Oriented Strand Board Composed of Thinned Wood of Larix leptolepis Gordon

낙엽송(落葉松) 간벌목(間伐木)을 원료(原料)로 한 Oriented Strand Board(OSB)의 목표밀도(目標密度)와 Strand Size가 OSB의 재질(材質)에 미치는 영향(影響)

This study was to manufacture thinned wood of Larix leptolepis Gordon into Oriented Strand Board(OSB) with Urea-Formaldehyde Resin. The OSB was made of four kinds of strand in slenderness ratio 150 ; thickness $0.3{\pm}0.05mm$, $0.4{\pm}0.05mm$, $0.5{\pm}0.05mm$ and $0.6{\pm}0.05mm$, respectively length 45mm, 60mm, 75mm and 90mm. Target densities were 0.65gr/$cm^3$, 0.75gr/$cm^3$ and 0.85gr/$cm^3$. The stepwise 9 minutes-multi-pressing schedule in the maximum pressure 40kgf/$cm^2$, the minimum pressure 10kgf/$cm^2$ was applied for $400mm{\times}390mm{\times}12mm$ board at the temperature of $150^{\circ}C$ in a hot press. In MOR The OSB of thin strand thickness $0.3{\pm}0.05mm$(length 45mm) and density 0.85gr/$cm^3$ was the highest. The strand thickness had more effect on MOR than the strand length. In strand thickness $0.4{\pm}0.05mm$(length 60mm) and density 0.85gr/$cm^3$ was the highest MOE. The strand thickness and length had adverse effects on MOE each other. At internal bonding. The OSB of strand thickness $0.3{\pm}0.05mm$(length 45mm) and board density 0.75gr/$cm^3$ showed the highest value. OSB had higher IB value with thinner strand thickness. The thinner strand thickness showed the lower thickness swelling in turn $0.3{\pm}0.05mm$(length 45mm), $0.4{\pm}0.05mm$(length 60mm), $0.5{\pm}0.05mm$(length 75mm). $0.6{\pm}0.05mm$(length 90mm). Target densities 0.75gr/$cm^3$ 0.65gr/$cm^3$, 0.85gr/$cm^3$ showed in turn lower value. Finally, The OSB made of thinned wood of Larix leptolepis Gordon showed good results in laboratory experiment.