Determination of heat-treated eucalyptus and pinus wood properties using NIR spectroscopy

Abstract

Near-infrared (NIR) spectroscopy associated with multivariate statistics has been successfully applied to a range of studies involving wood properties and its products. However, the use of NIR spectroscopy for technological classification of heat-treated wood is less common. Thus, the aim of this study was to estimate the equilibrium moisture content (EMC) , dimensional stability, stiffness and strength of heat-treated wood samples of Eucalyptus urophylla and Pinus oocarpa by NIR spectroscopy. Specimens taken from central boards were heat treated at 125, 150, 175, 200 and 225 °C. After heat treatment, the woods were kept in a climatic chamber until EMC was reached. NIR spectra were recorded and correlated to the wood properties determined in laboratory using multivariate statistics. It was possible to develop satisfactory models for estimating EMC (cross-validation coefficient (R2cv) = 0.94, ratio of performance to deviation (RPD) = 4) and modulus of rupture (R2cv = 0.86, RPD = 2.7) when considering both Eucalyptus and Pinus wood samples together. The model for volumetric swelling presented better statistics (R2cv = 0.93 and RPD = 3.8) when only Eucalytus sample was considered.