Fracturas en madera de eucalyptus nitens: Efecto de las propiedades mecánicas a nivel ultraestructural y de la anatomía celular

Abstract

This study was conducted to investigate the causes and posibles factors related to fractures in the cellular structure in Eucalyptus nitens. Nanomechanical cell wall properties at the middle lamella level (ML), S1 and S2 layers were evaluated. In addition, the area, and diameter of vessels were measured. These parameters were associated with extreme levels of cracking (high and low) in two Eucalyptus nitens families. The samples were taked from two sites of the 8th Region of Chile. The analysis of the ductility ratio (E/H) demonstrated that the ML is more brittle than the S1 layer; and the S1 is more brittle than S2 layer. The ML and S1 layer behave like resilient materials, but not the S2 layer. The difference in the modulus of resilience was related to higher shear stresses at the ML/ S2 and at S1/S2 interfaces. The characterization of the vessels showed that the families with greater level of cracking have also lower frequency and greater area and diameter of vessels Th S1 layer was weaker tan S2 layer and LM due to their difference in resistance between them and combined with the internal stresses might propagate the microcracks.