Preliminary studies on the selection of Uruguayan woods for the production of transparent wood.

Transparent wood has garnered significant attention in recent years due to its high optical transmittance, safety, lightweight nature, excellent mechanical robustness, and low thermal conductivity, all of which make it an energy-efficient building material. To turn it transparent, wood needs to be chemically bleached, a process by which lignin and extractives are removed. Then, a polymer with a refraction index similar to that of delignified wood is integrated into its structure to reach high optical transparency. In this preliminary work, two common wood species in Uruguay were compared to determine which is more suitable for the process, as their characteristics are very different. Pinus taeda is a coniferous species of low-density and low extractive content; meanwhile, Eucalyptus bosistoana is a hardwood of high density and high extractive content. The behaviour of two wood species was compared. Delignification was carried out with NaCl₂; the effects of temperature and NaCl₂ concentration were studied; and the delignified wood was finally impregnated with epoxy resin. The FTIR spectra were analysed, and the anatomy of the wood at each stage was analysed with SEM. The results suggest both wood species grown in Uruguay are suitable for the development of transparent wood; the delignification conditions turned out to be the most consequential factor. The best delignification conditions were a reaction time of 300 minutes, a NaClO₂ concentration of 3.5% at a constant temperature of 80°C, and a second round of bleaching with H₂O₂ for one hour at 80°C.