STUDY OF THERMAL EXPANSION AND COMPRESSION STRENGTH OF THREE WOOD SPECIES FROM PLANTATIONS

ABSTRACT

The objective of this study was to evaluate the effect generated by a thermal treatment on the dimensional changes and compression behavior of three wood species from commercial plantations (Eucalyptus nitens, Tectona grandis and Gmelina arborea). To accomplish the goal, dilatometric and compression tests were performed in the three directions of wood. It was found a high anisotropy of the coefficient of linear thermal expansion (CTE) as well as of the compression strength of the woods. Higher values of CTE in the tangential direction than in the radial direction were measured, meanwhile in the longitudinal direction were null. In terms of mechanical strength, the longitudinal direction showed the highest strength. The radial strength was slightly higher than the tangential one. Thermal treatment increased the strength to compression and the resistance to deformation in the elastic region. The modulus of elasticity increased up to 30.9%, the stress at proportional limit up to 27.3% and the modulus of rupture up to 30.3%, in the longitudinal direction. The thermal treatment had a higher effect on the mechanical properties of the lowest density wood. On the contrary, the mass loss increased for these species, finding values around twice than those obtained for the denser wood.

Keywords:
Wood orientation,Thermal treatment; Dilatometry; Mechanical strength