Role of α-Fe2O3 nano-particles in protecting wood from ultraviolet light degradation

Abstract The incorporation of nano-particles into coatings to protect wood against UV light has tremendous potential for improving coating performance. However, the understanding of the mechanisms by which these particles function on wood surfaces remains limited. The distribution and potential chemical interactions between alpha Fe2O3 and wood were studied. The ability of different sizes of Fe2O3 particles to intercept various wavelengths of light was assessed using ultraviolet/visible (UV–vis) spectroscopy using TiO2 and ZnO particles for comparison. All particles intercepted UV light, but α-Fe2O3 also intercepted a portion of the visible spectrum which might help explain its better performance. Scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM-EDS) analysis of α-Fe2O3 nano-particle distribution on different wood orientations of radiata pine (Pinus radiata D. Don) and shining gum (Eucalyptus nitens) showed that iron particles were uniformly distributed on both pine and shining gum, but provided better UV protection to the more permeable radiata pine surfaces. Characterization of chemical interactions between α-Fe2O3 and isolated lignin and cellulose by Fourier Transform Infrared Spectroscopy (FTIR) suggested substantial interactions between these particles and lignin components, but little interaction with cellulose. The results suggest that the role of nano-particles in the UV protection of wood surface is to intercept and disperse the light energy while interacting with the wood.