This study investigated the sorption behaviour of thermally and chemically modified selected Entandrophragma utile (Meliaceae) wood species for the purpose of quality improvement. E. utile wood samples with 8000 mm3 dimension were used in this study. The samples were oven dried and thermally treated at temperatures of 160, 180 and 200°C for 30 min. Another set of wood samples were prepared for chemical treatment inside an oven at 80°C for 180 min. The colour varied from light cream to slightly brown at 160°C and very brown at 200°C for thermally modified wood. The colour of the chemical modified wood changed from being yellowish of the untreated wood to pale yellow in colour. The percentage weight loss increased with temperature from 22.62% at 160°C to 26.46% at 180°C and 20.8% for percentage weight gain. The average value of water absorption ranged from 8.60 to 16%; 26 to 40.78%; 35 to 50.35% and 42.88 to 57.53% for 1 h to 78 h, respectively. The value for the chemically modified wood ranged between 5.22 and 5.59%, with relative humidity of 97 and 7%, having the lowest and highest value, respectively. The study revealed that there was a reduction in the weight and density of thermally treated wood as a result of thermolysis and the weight gain from chemical modification.
Keywords: Entandrophragma utile, sorption, water absorption, temperature, colour, density.