Propriedades tecnológicas da madeira Eucalyptus grandis impregnada com nanofluidos de sílica.

Abstract

The present study aimed to reduce the time required for the thermal treatment of Eucalyptus grandis wood in linseed oil, previously impregnating it with silica nanofluids derived from rice husk ash. For this, silica nanoparticles were synthesized from rice husk ash by refluxing in 6N HCl for 1.5 h, boiling in 2.5 M NaOH at 80 °C for 1.5 h and washing in H2SO4. Part of the nanosilica obtained was sintered at 1100 °C for 3 h in a muffle. The nanosilicas were characterized by means of FTIR and XRD. Amorphous silica and sintered silica nanofluids were prepared in ultrasonic baths containing 250 ml of linseed oil, 2.225 g of silica and lasting 2.5 h at a time. Sixty-five samples of Eucalyptus grandis wood with dimensions of 15 × 15 × 250 mm were separated. Fifteen samples were impregnated with linseed oil, 15 with amorphous silica nanofluid and 15 with sintered silica nanofluid, using an initial vacuum of 600 to 700 mm Hg for 15 min and positive pressure of 8 bar for 90 min. 5 samples from each group were thermally treated in linseed oil at 210 °C for 1 h, 2 h and 3 h. In the characterization of wood samples, physical properties, maximum bending stress (σmax), modulus of elasticity (E), surface hydrophobicity and colorimetry were evaluated. It was verified that, in general, in relation to the control samples, as a result of the treatments, in the thermo-treated woods, its equilibrium moisture content was reduced, its dimensional stability was improved, its resistance to water repellency was increased. water, there was an increase in its density, a loss of mechanical resistance, a greater hydrophobicity, with emphasis on the samples impregnated with sintered silica nanofluid, which presented the most hydrophobic behavior and, in colorimetric terms, with few exceptions, the thermo woods -treated images darkened, tended toward green and blue, and reduced their color saturation and ink angle.