Heat treatment on keruing and light red meranti: The effect of heat exposure at different levels of temperature on bending strength properties

Heat treatment on timbers is a process of applying heat to modify and equip the timbers with new improvised characteristics. It is environmental friendly compared to the common practice of treating timber by chemical preservatives. Malaysian hardwood timbers namely Keruing and Light Red Meranti which are in green condition were heat treated at temperature 150°C, 170°C, 190°C and 210°C, in a specially designed electronic furnace within one hour duration. The objectives were to determine the effect of heat treatment on bending strength properties of heat treated timbers in terms of Modulus of Elasticity (MOE) and Modulus of Rupture (MOR) and to examine the significance changes at each temperature level. Untreated samples for each species were used as a control sample. The results indicated that the bending strength properties for both species of timbers were affected by the heat exposure. Both MOE and MOR values for heat treated Keruing were increased when subjected to the temperature levels at 150°C, 170°C and 190°C except at 210°C. Heat treated Light Red Meranti shows the same pattern of increment on its MOE and MOR values after exposure to heat at three temperature levels applied and the values dropped at 210°C. However, for both of species, even though there were decrement occurred at 210°C, the value is still higher compared to the control sample. The increments of MOE and MOR values are an indicator that heat treatment had successfully improvised the bending strength properties of these two species of hardwood timber.