Effect of extractives on three physical properties in Enterolobium cyclocarpum from Michoacan, Mexico

Abstract

The presence of extractives in wood has an important effect on its properties and its transformation processes. The aim of this work was to study the effect of extractives on dimensional variation, density and the fiber saturation point of Parota heartwood (Enterolobium cyclocarpum). The behavior of non-extracted specimens was compared to that presented by specimens extracted with acetone and ethanol-water (1:1). The extraction with acetone was performed using soxhlet equipment during effective times of 120 hours of reflux and 260 hours submerged in the solvent; the extraction with ethanol-water (1:1) was achieved in 155 and 370 hours respectively. It was found that extractives give less dimensional variation to Parota hardwood, because they produce a "bulking" effect in the cellular wall which reduces the shrinkage and swelling of wood. This effect was statistically significant in radial, tangential and volumetric determinations; while in longitudinal measurements, this effect was not significant. Density was not affected by the removal of extractives in Parota heartwood. The presence of extractives caused a reduction in the fiber saturation point, this was proved using Stamm’s and Babiak and Kúdela’s equations.