Effect of H2O2 Bleaching Treatment on the Properties of Finished Transparent Wood

Abstract

Transparent wood samples were fabricated from an environmentally-friendly hydrogen peroxide (H2O2) bleached basswood (Tilia) template using polymer impregnation. The wood samples were bleached separately for 30, 60, 90, 120 and 150 min to evaluate the effects on the changes of the chemical composition and properties of finished transparent wood. Experimental results showed decreases in cellulose, hemicellulose, and lignin content with an increasing bleaching time and while decreasing each component to a unique extent. Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM) analysis indicated that the wood cell micro-structures were maintained during H2O2 bleaching treatment. This allowed for successful impregnation of polymer into the bleached wood template and strong transparent wood products. The transparent wood possessed a maximum optical transmittance up to 44% at 800 nm with 150 min bleaching time. Moreover, the transparent wood displayed a maximum tensile strength up to 165.1 ± 1.5 MPa with 90 min bleaching time. The elastic modulus (Er) and hardness (H) of the transparent wood samples were lowered along with the increase of H2O2 bleaching treatment time. In addition, the transparent wood with 30 min bleaching time exhibited the highest Er and H values of 20.4 GPa and 0.45 GPa, respectively. This findings may provide one way to choose optimum degrees of H2O2 bleaching treatment for transparent wood fabrication, to fit the physicochemical properties of finished transparent wood.