PROPERTIES OF THERMALLY-COMPRESSED OIL PALM TRUNKS (<em>ELAEIS</em> <em>GUINEENSIS</em>)

Abstract

The objective of this work was to evaluate the properties of thermally-compressed oil palm trunks (Elaeis guineensis) using hot press process. Samples were compressed at three press temperatures, i.e. 140, 180 and 220 °C under maximum pressure of 2 MPa for 8 min. Average oven-dry density of compressed samples increased from 0.34 to 0.71 g cm-3 compared with control samples. Both the modulus of rupture and modulus of elasticity of samples also increased with densification. The hot pressing increased hardness and brittleness of the samples but caused some loss of hardness when higher temperatures were used. The thermally-compressed samples had higher thickness swelling values than control samples due to spring back of cell wall when they were soaked in water. The combination of compression and heat resulted in specimens with smooth surfaces. The increased surface density reduced adhesive bond strength of samples. Contact angle measurement of samples using water decreased with increasing temperature due to cracks of cell walls of parenchyma cells after compression at high temperature. Thermally-compressed oil palm wood samples appeared to possess better mechanical properties but thickness swelling was adversely affected. The pressure, temperature and duration of hot pressing need to be optimised for specific applications.