THERMAL COMPRESSION EFFECT ON SEVERAL PROPERTIES OF 8-YEAR-OLD WARU GUNUNG (HIBISCUS MACROPHYLLLUS) WOOD

The study aimed to investigate the effect of thermal compression on the properties of 8-year-oldwaru gunung wood. Wood specimens with the dimension of 25 mm100 mm150 mm in thickness,width and length, respectively were heated at 180 ̊C and 200 ̊C for 4 h. During the heating process,the specimens were subsequently compressed at 2.452 N mm−2 for 40 mins at each temperature.Changes in the wood chemical structure were examined using the pyrolysis-gas chromatography-massspectrometry, the wood physical properties were tested according to ASTM D143-94, the wood surfacehardness was tested using a Universal Testing Machine and the wood discoloration was examinedusing the CIELab method. The changes in crystallinity degree was examined using x-ray diffractionand cell structure were collected as supporting data. Results showed that the thermal compressionat 180 ̊C and 200 ̊C caused severe degradation on the specimen carbohydrate but less for lignin.The sum effect of thermal compression on the specimens also consecutively increased the density by34.24% and 41.87% and surface hardness by 52.78% and 63.09% and decreased the swelling thicknessby 38.54% and 47.03% and the equilibrium moisture content by 36.53% and 38.59% at 180 ̊C and200 ̊C, respectively. Thermally compressed specimens also had darker colours, glossier surfaces andsmoother texture compared to non-thermally compressed specimens.