Zaščita lesa pred sevanjem UV s premaznimi sistemi z nanodelci : doktorska disertacija
Protection of wood against UV radiation with nano-coatings : doctoral dissertation

slovenian

doktorska dela

2016

wood coatings   hydrothermal deposition

Univerza v Ljubljani, Biotehniška fakulteta

Nanoparticles of titania (TiO2) for the UV-protection of wood were prepared by two different processes. The first, "bottom-up", process was the hydrothermal deposition of TiO2 from aqueous solution of TiCl4 and HCl at low temperatures (75 °C). The characterization and detection of the synthesised crystalline structure of TiO2 on surfaces of wood was carried out by EDX, SEM and FT-Raman spectroscopy. The quantity, shape and crystalline form of the deposited nano-crystals of TiO2 could be controlled with the reaction parameters - time, temperature and concentration of HCl in the reaction mixture. The content of water in the samples during the hydrothermal deposition process has a positive impact on the reduction of surface mechanical damage, cracks that can appear during the modification process. The deposition process exhibited also some secondary effects: mechanical properties were reduced and hydrophobicity was increased. The second principle was "the top-down approach", where the coated titania nanoparticles were prepared from the commercial TiO2 rutile pigment called CCR. Polyhedral oligomeric silsesquioxane (POSS) was used as a particle surface modifier. During the processes of milling and surface modification, the particle size was reduced and the stability of the dispersion in an organic solvent was significantly increased. Both UV-absorbing systems (the titania deposits and coated nanoparticles) were applied in various surface coating systems, where their synergistic efficacy was checked as well. The surface systems were: impregnating oil and acrylic, alkyd and polyurethane paints. It was shown that the process of the hydrothermal deposition was suitable for oil impregnation, while the addition of the coated titania nanoparticles was more effective in the other surface protective systems. Bleaching of liquefied wood was successfully performed.

28.12.2016