9325 KB375 KB2016Orel, BorisPetrič, MarkoPori, PavelXVIII, 177 f., 30 cmCOBISSID:2646921URN:URN:NBN:SI:doc-F6B501LOslP. Porivisokošolska delaDisertacijehidrotermalna depozicijahydrothermal depositionLesNanodelcinanoparticlespremazi za lesTiO2Titanov dioksidUV-protectionUV-zaščitawood coatingsZaščitaZaščita lesa pred sevanjem UV s premaznimi sistemi z nanodelci| doctoral dissertation| doktorska disertacija| Protection of wood against UV radiation with nano-coatings|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 performedPreverili smo učinkovitost nanodelcev titanovega dioksida (TiO2) za zaščito lesa pred UV-svetlobo. Nanodelce smo pripravili po dveh različnih postopkih. Pri prvem, "od spodaj navzgor", smo izvedli hidrotermalno depozicijo TiO2 iz vodne raztopine TiCl4 ter HCl pri nizkih temperaturah (75 °C). Z EDX-, SEM- ter FT-ramansko spektroskopijo je bila potrjena ter okarakterizirana uspešnost sinteze rutilne kristalne strukture TiO2 na površini lesa. Z reakcijskimi parametri - čas reakcije, temperatura ter koncentracija HCl v reakcijski zmesi - je mogoče vplivati na količino, velikost ter strukturo deponiranih nanokristalov TiO2. Vsebnost vode v vzorcih med potekom hidrotermalne depozicije pozitivno vpliva na zmanjšanje števila površinskih mehanskih poškodb, razpok, ki se lahko pojavijo med postopkom modifikacije lesa. Hidrotermalna depozicija ima tudi stranske učinke: slabša mehanska odpornost ter večja hidrofobnost površine. Drugi princip priprave nanodelcev pa je bil "od zgoraj navzdol". V tem primeru smo pripravili nanodelce iz komercialnega TiO2 rutilne oblike, to je CCR. Delce smo oplastili s poliedričnim silseskvioksanom (POSS). S postopkom mletja ter oplaščanja se je velikost delcev znižala, njihova stabilnost v disperziji pa se je bistveno zvišala. Oba sistema uporabljenih UV-absorberjev ter njuna sinergijska učinkovitost je bila preizkušena pri različnih zaščitnih površinskih sistemih: olju ter akrilnem, alkidnem in poliuretanskem premazu. Izkazalo se je, da je postopek hidrotermalne depozicije primernejši za oljne impregnacije, medtem ko je dodajanje oplaščenih nanodelcev TiO2 primernejše za ostale preizkušene premazne sisteme. Uspešno smo izvedli razbeljenje utekočinjenega lesaTEXTvisokošolska delatheses and dissertationsSlovenian National E-content AggregatorNational and University Library of SloveniaUniverza v Ljubljani, Biotehniška fakulteta