An Evaluation of the Physicochemical, Structural and Morphological Properties of Selected Tropical Wood Species for Possible Utilization in the Wood Industry

This work investigated and quantified the physicochemical, structural and morphological properties of four (4) tropical timbers as precursor raw materials for possible utilization in the wood plastic industry. The physicochemical properties of the wood samples such as the bulk and tapped density, moisture content, water absorption capacity at 25°C, volatile content, fixed carbon, ash content, alpha cellulose, hemicellulose, lignin, and extractives contents were determined using standard methods like the European Committee for Standardization and (CEN/TS) and the American Society for Testing Materials (ASTM) standards. The structural and morphological properties of the samples were examined with Fourier Infrared Transform (FTIR) spectroscopy and scanning electron microscope (SEM). Results indicated that the bulk density values of the timbers ranged from 0.34 g/cm3 in Brachystegia eurycoma (W3) to 0.47 g/cm3 in Erythrophleum suaveolens (W2), with the other timbers, Nuclea diderichii (W1) and Prosopis africana (W4) having the same bulk density of 0.40 g/cm3. With respect to their moisture content, W2 had the highest value (8.38%) while Nauclea diderrichii had the lowest value (6.52%). The water absorption capacities of the woods studied correlated with the cellulose composition of wood in the order of: W3 > W1 > W4 > W2. The FTIR results showed that W2 and W3 presented a slightly more prominent and broader band than the other woods at 1731 cm-1, in agreement with the higher holocellulose content of these species, while W2 and W4 presented the most prominent peaks indicating higher lignin content than W1 and W3. The SEM micrographs of the wood flour samples investigated indicated that the surfaces of the woods were rough and heterogeneous with irregular crystal and brick shaped particles. A two-way analysis of variance (ANOVA) carried out with respect to the chemical composition of the wood samples indicated that there was no statistically significant variation in the wood chemical composition between species as the p-value (0.852) obtained was greater than the critical level of α = 0.05.