Variation in bending strength properties in stem and branch woods as influenced by density and moisture levels in Entandrophragma cylindricum

Abstract

Branchwood is being exploited as a supplement to stemwood in wood products manufacturing, and the wood�s bending strength properties are vital for structural and non-structural applications. Non-destructive methods are being adopted in determining wood properties, and wood density and moisture content are two variables that could be useful. This study assessed the influence of density and moisture content (MC) on the Modulus of Elasticity (MOE) and Modulus of Rupture (MOR) of branch and stem woods of Entandrophragma cylindricum (sapele) tested at two moisture levels (10���4% MC and 17���3% MC). Density was determined in accordance with ISO 3131. To determine bending strength properties, BS 373 was followed, using an INSTRON TCM Machine with a crosshead speed of 6.6�mm per minute. Results indicated that branchwood has higher density than its stemwood counterparts. MOE and MOR of both wood types were significantly higher at 10���4% MC than their counterparts at 17���3% MC. Differences in MOE and MOR between the wood types were not significant, although the branchwood had 87% and 93% respectively of the MOE and MOR of stemwood. From the two-way ANOVA, MC had a significant effect (P�<�0.05) but wood type and the interactions of wood type and MC did not have a significant effect on MOE and MOR of stem and branch woods. The predictive powers of MC and density as a combined predictor for estimating bending strength properties were higher for branchwood than stemwood. Although density of E. cylindricum branchwood was significantly higher than its stemwood counterpart that did not translate into significant differences between MOE and MOR of branchwood and stemwood. � 2016 Institute of Foresters of Australia (IFA).