Effects of H₂O₂ chemical modification on the physical and optical properties of Eucalyptus grandis W.Hill wood

Abstract

Background: Wood bleaching is used for applications such as the production of uncoated furniture and laminated boards. However, there has been limited research on applying this treatment to Eucalyptus wood, and existing studies often involve reagents that are harmful to both the environment and human health. This study aimed to evaluate the physical and optical properties of Eucalyptus grandis W.Hill veneers following chemical modification with hydrogen peroxide.

Methods: Twenty-seven H₂O₂ bleaching treatments were conducted, varying in time (30, 60, and 90 minutes), temperature (60, 70, and 80°C), and pH (4, 6, and 8), and were compared to a control treatment. Tests comprised measuring density, 24-hour water absorption, wettability, brightness, whiteness, yellowness, and CIELab* colour scale.

Results: Bleaching modified the wood’s properties, particularly increasing brightness and whiteness. While density and water absorption did not significantly change with treatment, wettability increased after bleaching, promoting bonding quality for the production of laminated boards. The treatment conducted at 70°C, with an alkaline pH of 8 for 90 minutes, showed the most favourable results.

Conclusions: These findings demonstrated the potential of hydrogen peroxide bleaching as a technique for enhancing physical and optical properties of wood veneers.