Monitoring Changes in the Colour, Strength and Chemical Properties of Oil Heat Treated 18-Years Old Cultivated Acacia mangium

Acacia mangium a fast-grown timber species is an important for large scale forest plantation in
Malaysia. A study carried out to investigate changes in colour, strength and chemical properties in the
oil heat treated 18-years old cultivated Acacia mangium. Harvested trees segregated into bottom,
middle and top portions containing heartwood and sapwood were oil heat treated in stainless tank
with palm crude oil as heating medium at temperatures of 180°C, 200°C and 220°C for 30, 60 and 90
minutes, respectively. The evaluation of the changes in the wood were performed by standards using
a Minolta Chroma Meter, TAPPI Standard T204 om-88, TAPPI Standard T203 cm-99, TAPPI
Standard T222 cm-02, and BS EN 310:1993 static bending tests. The relationship between the
changes in the colour, mechanical and chemical composition, were made using correlation analysis.
The result showed oil-heat treatment reduced the lightness of the wood and darkened both parts of
the wood. The strength of the wood reduced slightly after the oil-heat treatment. In the chemical
compositions, the percentages of the holocellulose, α-cellulose, hemicellulose and extractive contents
decrease with the increase in treatment duration and temperature. The oil heat treatment process
enhanced the colour of sapwood to match the heartwood of 18-year old Acacia mangium. The oil
heat treatment process at 200°C for duration 60 minutes is recommended for A. mangium wood as it
improved the colour of A. mangium and standardized the colour of sapwood and heartwood. The loss
in strength at this temperature and duration is acceptable as the treated wood only loss up to 15%
strength in MOR and 10.7% in MOE.