Effect of Thermal Treatment on Chemical, Biological and Mechanical Properties of African Whitewood (Triplochiton scleroxylon K. SCHUM)

Abstract

The thermal modification of wood is a potential alternative method for improving wood properties. This paper evaluates the effect of thermal treatment on the chemical, biological and mechanical properties of African Whitewood (Triplochiton scleroxylon K. Schum) by subjecting the wood to three temperature (200, 170, 140 ℃) at three different time (3, 6, 12 h). Fourier Transformed infrared (FT-IR) spectrometer was used to ascertain the effect of heat treatment on the chemical constituent of the wood while mechanical properties were determined by Modulus of Elasticity (MOE) and Modulus of Rupture (MOR). Durability of heat-treated wood against subterranean termites using field test was also investigated.  FTIR results provided information on the chemical constituents after heat treatment revealing the cellulose and hemicelluloses of Triplochiton scleroxylon wood samples. The decreasing intensity of hydroxyl groups stretching at 3341 cm-1 indicated that heat-treated samples have lost some of their hydroxyl groups. The results showed that the MOR of heated-treated wood at 200 ℃ was significantly higher than the untreated samples. There was also a 26% increase in the MOE of the 170 ℃ heat-treated wood relative to untreated samples. Wood samples thermally treated at 170 ℃ and 200 ℃ as well as untreated wood samples were strongly degraded in term of weight loss (WL) by termite though the degree of degradation varied based on temperature and time in which the wood was modified. However, heat-treated wood at 140 ℃ gave the lowest WL of 20.41% compared to other treated and untreated wood samples. Therefore, strength properties and termites’ resistance of African whitewood also known as Obeche wood in Nigeria could be improved when thermally modified at 170 ℃ and 140 ℃ respectively.