Somjot Chirasatitsin, Suteera Prasertsan, Worawut Wisutmethangoon and Buhnnum Kyokong

pp. 1047 - 1055

Abstract

Effect of strand length on mechanical properties (tension, compression and bending) of oriented
strand lumber (OSL) made of rubberwood (Hevea brasiliensis Muell. Arg.) was reported. Three strand
lengths of 50 mm, 100 mm, and 150 mm with 1 mm thickness and 15 mm width were used. The strands were
mixed with 5% pMDI glue (weight basis) in a tumble mixer. The OSL specimens were formed by hot pressing
process of unidirectionally aligned strands. Average specific gravity and moisture content were 0.76 and
8.34%, respectively. Tension and compression tests were carried out for directions both parallel and perpendicular to grain while bending test was performed only in parallel direction. Ultimate stresses and moduli
of elasticity were examined from the stress-strain curves. It was found that for the parallel-to-grain direction,
the longer strand OSL gave higher strength. The role of the strand length did not appear for the direction
normal to the grain. The relationship between the mechanical properties of OSL and strand length was well
described by the modified Hankinson formula.

Keywords

• rubberwood
• oriented strand lumber
• composite wood
• strand length
• mechanical properties