HYDROTHERMAL TREATMENT OF <em>EUCALYPTUS</em> STRAND PARTICLES FOR IMPROVEMENT OF ORIENTED STRAND BOARD (OSB)

Abstract

The aim of this study was to evaluate the effect of hydrothermal treatment on the chemical composition of Eucalyptus strand particles and on the physical and mechanical properties of oriented strand board (OSB) panels. Strand particles of Eucalyptus were pre-hydrolysed at 130, 150 and 170 °C for 7 and 21 minutes. The extractives, lignin, carbohydrates, pH, equilibrium moisture content, mass loss and contact angle were evaluated. The OSB panels were fabricated using a phenol-formaldehyde adhesive (8%), 0.7 g cm^-3 nominal density and a pressing cycle with 170 °C, 3.14 MPa for 8 minutes. These panels were kept in a climate chamber at 20 ± 2 °C and 65 ± 3% relative humidity to determine their physical and mechanical properties. The hydrothermal treatment, mainly at 170 °C, degraded the hemicelluloses, especially galactans, xylans and arabians. The treatments at this temperature showed the best results for improving the dimensional stability, as well as reducing the moisture equilibrium content, water absorption and thickness swelling after 24 hours of immersion, without losing mechanical resistance. Therefore, hydrothermal treatment can be an important alternative for improving OSB panel quality.