Abstract:
Oil palm trees, planted for palm oil production, are generally felled for replanting after about 25 years when the palm oil production becomes uneconomical. Oil palm biomass including oil palm trunks, available in large amounts, has not been effectively utilized. Large variations in the physical and mechanical properties have caused many difficulties in use of the wood for applications. This thesis explores the possibility of using low density oil palm trunk as a core section of a sandwich panel overlaid with rubberwood veneer faces.
Sandwich panels consisting of an oil palm wood core and rubberwood veneer faces were first manufactured in laboratory. Four manufacturing parameters were examined, i.e., three levels of melamine-urea-formaldehyde (MUF) adhesive content (150 g/m2, 250 g/m2 and 350 g/m2 solid basis), three different rubberwood veneer thicknesses (0.7 mm, 1.8 mm and 2.7 mm), three different oil palm wood core densities (22314 kg/m3, 30135 kg/m3 and 41833 kg/m3) and two types of grain orientation of the oil palm wood core (parallel and perpendicular to the panels surface). Some physical properties including panel density, thickness swelling (TS), water absorption (WA) and thermal conductivity () and mechanical properties including screw withdrawal resistance (SWR), modulus of elasticity (MOE) and modulus of rupture (MOR) of the sandwich panels were investigated. The center point bendings stiffness and strength of the produced sandwich panels were modeled as functions of density and grain orientation of oil palm wood core, rubberwood veneer thickness and span length using linear elastic beam theory. Finally, the manufacture of commercial-size sandwich panels was performed using an industrial plywood production line.
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The oil palm wood core sandwich panels were successfully manufactured with a density of less than 500 kg/m3, classified as a lightweight material. The level of resin content within the range studied did not influence any properties of the panels. Higher core density (200-450 kg/m3) increased the values of (0.060.11 W/m.K), SWR (410-908 N), MOR (15.8-46.3 MPa) and MOE (5,472-9,323 MPa) but decreased the value of WA (172-51 %) without an effect on the TS of the panels. Panels with the core grain direction oriented perpendicular to panels surface possessed lower values of TS but higher values of and strain at fracture when the panel failed in a mode of core shear under bending test than those oriented parallel.
The relationship between panel density and the measured WA, and SWR of the sandwich panels expressed as mathematical equations could be used to predict and design the expected properties of this type of sandwich panel. The linear elastic beam theory used with expressions of the Youngs moduli and shear strength of the oil palm wood as a function of density adequately predicted the bending stiffness and strength of the sandwich beams. The stiffness and failure load equations of the oil palm wood core sandwich panel were also proposed for practical uses of this product.
Finally, the commercial-size oil palm wood core sandwich panels overlaid with rubberwood veneer faces were successfully manufactured using an existing industrial plywood production line. Lightweight prototype furniture, i.e., a table and chair were constructed from the panels produced. The sandwich panel made using oil palm wood as a core could add the value to leftover oil palm trunks by converting it into strong lightweight panels. This product has good potential for lightweight furniture applications and structural insulated uses such as walls or ceilings in the building sector.
WALAILAK UNIVERSITY. CENTER FOR LIBRARY RESOURCES AND EDUCATIONAL MEDIA