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Submitted February 2017; accepted May 2017
Timber from forest plantation can be an alternative to overcome the shortage of raw material for plywood manufacture. However the use of fast growing species may affect the plywood quality. This study investigated the mechanical properties of plywood made from three fast growing species which is batai (Paraserianthes falcataria), eucalyptus (Eucalyptus pellita) and kelempayan (Neolamarckia cadamba). Plywood with five and seven layers veneer were produced with different species arrangement. Bending, bonding shear and panel shear properties of the plywood were determined according to Japanese Agricultural Standard for Plywood. Results showed that the number of layer and veneer thickness affected the board properties. Plywood with seven layers performed better than five layers, showing higher modulus of rupture, modulus of elasticity and bonding shear. Species arrangement affected modulus of rupture, modulus of elasticity, bonding shear and panel shear. Plywood from kelempayan and kelempayan-eucalyptus arrangement performed better than plywood containing batai veneers.
Keywords: Japanese Agricultural Standard for Plywood, forest plantation, raw material, plywood manufacture, fast growing species
INTRODUCTION
Plywood is a kind of wood panel made from sheets of veneer and combined under pressure with an adhesive. It is constructed with veneer grain direction of adjacent layers oriented perpendicular to one another (Youngquist 1999). In the past, Malaysian plywood mills were accustomed to process good quality timber from the forest which are straight, of large diameter and cylindrical form, having straight grain and comparatively free from defects (Wong & Wong 1981). However, the log supply has become critical as the forest resources further diminished. The production of logs decreased from 40.1 million m3 in 1990 to 15.9 million m3 in 2012 (DOSM 2013). As an alternative, logs from plantation can be considered to overcome the raw material shortage. However the use of fast growing species may affect the plywood quality. Studies showed that plywood from rubberwood (Hevea brasiliensis) and Acacia mangium plantations can be produced with some modifications to the process (Wong 1979, Wong et al. 1988). Veneer with high density, mixed with lower density species, can improve the durability and strength of plywood from low density species (Aydin & Colakoglu 2008).
Batai (Paraserianthes falcataria) and kelempayan (Neolamarckia cadamba) are among species that had been selected for forest programme in Malaysia...