A rectangular core with dimensions of 260 mm (width) × 520 mm
(length) was formed by bonding eight pieces of oil palm wood specimens
with the same grain direction, thickness and density range side
to side with polyvinyl acetate (PVAc) adhesive. MUF resin was spread
onto the rough surface of the rubberwood veneer with a hand brush.
The resin content used in this experiment was 250 kg/m2 (solid basis)
[1]. The glued veneers were then placed on the top and bottomsurfaces
of the prepared core so that the grain of the veneerwas oriented parallel
to the panel's length. Two types of panels, having the grain direction of
oil palm wood core aligned parallel (PR boards) and perpendicular (PP
boards) to the surface as illustrated in Fig. 2b and d, respectively, were
manufactured. The assembled mats were then put into the placing
space of a single-opening hydraulic lab hot press (60 × 60 cm2 Wabash
MPI, USA). Two 20mmthick steel stopperswere placed on both sides of
the assembled mat to control the final thickness of board during pressing.
The assembled mats were then pressed with the platen heated to
160 °C at 2 MPa for 5 min.
The PR boards were produced at three different veneer thicknesses
(0.7 mm, 1.8 mm and 2.7 mm) and all three different core densities.
Both faces of the sandwich boards produced had the same veneer thickness.
The thickness of the core (18.6 mm, 16.4 mm and 14.6 mm) was
chosen such that the thickness of the boards produced was 20 mm.
The PP boards were produced using the 2.7 mm thick rubberwood veneer
as faces and the 14.6 mm thick oil palm wood with density of
Fig. 2.