During the project, various protective systems containing nano particles of ZnO, CeO2 and TiO2 for thermally modified wood were developed and tested. The objective was to diminish negative effects of weathering, especially UV light on visual appearance of wood. The protective systems should in spite of protective layer on surfaces of wooden elements retain as much as possible original texture and colour of thermally modified wood and diminish greying of surfaces during exposure to weather.
The results showed, that preparation of suitable dispersions of nano particles for impregnation of wood from commercially obtainable nano particle preparations is possible. It is possible also to prepare nano particles by the bottom-up procedure, in solutions of suitable precursors. The original intention was to carry out the so-called envelope treatment of wood with nano particle containing formulations, predominantly to decrease the needed application rate of expensive nano particle dispersions. However, the envelope treatment was not reached, so we performed classical entire cross section vacuum-pressure impregnation method. It was shown that nano particles were successfully delivered into the wood structure, although some agglomeration occurred and the particles found in wood were also in the micron size range. Originally, research with ZnO and CeO2 was planned, but the research was in a large part expanded also to TiO2.
Convenient thermal modification parameters for wood (mainly beech wood, but some other wood species were also investigated) were set up. It is important, that two treatment procedures were found to be possible: at first, wood was thermally modified and afterwards impregnated, or it was firstly impregnated and only then thermally modified in vacuum. This second option represents a novelty in this filed of the research. In continuation, various properties (humidity, water uptake, hydrophobicity) of variously treated and control samples were determined. The most important parts were WPs 5 and 6, where UV stability of the treated wood samples was evaluated and fungal resistance assessed, respectively. While in the case of UV stability the reverse order of protection of wood (at first impregnation with nano particles and only then thermal modification in vacuum) did not show any benefits, in the case of protection against fungal decay, among all samples, the best protection was assured exactly by this method.
The results of the training were disseminated in the form of 3 open access research papers and the project was promoted (outreach activities) by some other ways: interview with the fellow in a Slovenian research journal, presentation to co-workers at University of Ljubljana, Biotechnical Faculty, Dept. of Wood Science & Technology, at the events organised by University of Ljubljana and Chamber of Commerce and Industry of Slovenia, and on various social media.
