Chemical characteristics of woods from several Chilean native forest species and their relationship with nanomechanical cell properties

Abstract

The objective of this research was to study the chemical and nanomechanical characteristics of native woods grown in southern Chile region. The species analysed were Drimys winteri, Laureliopsis philippiana, Aextoxicon puctatum, Nothofagus alpina, Nothofagus dombeyi, Laurelia sempervirens, Austrocedrus chilensis and Fitzroya cupressoides. The samples were collected from the regions of Biobío (37° S, 73° W), Araucanía (37° S, 71° W) and Los Lagos (40° S, 73° W). Chemical analysis reported that glucan content of native woods was between 39% and 44% and lignin content between 28% and 35%. The nanomechanical properties analysed in the secondary cell wall (S2 layer) and middle lamella (ML) were elastic modulus (E), hardness (H) and ductility ratio (E/H). Values for E_S2 were between 12.0 and 15.4 GPa and for E_ML between 4.3 and 6.6 GPa. Hardness values were similar in ML and S2 (≈0.3 GPa). The compilation of results showed high correlations between E_S2 and carbohydrate content (r = 0.80), between E_S2 and hemicellulose content (r = 0.89), and between H_S2 and lignin content (r = 0.88).

Keywords: cell wall properties, chemical characterisation, nanoindentation, native woods