Periodic Reporting for period 1 - NewSiest (Enhancement of UV stability of thermally modified wood through envelope impregnation with nano-based stabilisers)
Reporting period: 2020-02-03 to 2022-02-02
Wood is sustainable material which is gaining in importance as a green, recyclable and carbon storage material that can have a significant role in tackling climate changes. There are some properties that prevents its wider applications, like dimensional instability and susceptibility to degradation by insects and micro-organisms and to weathering. One possibility to improve these properties is thermal modification. Thermally modified wood retains as a natural product and the grain, original colour variances and characteristics of wood are still present. However, exposure to daylight causes brightening or greying of heat-treated wood surfaces. In order to tackle this challenge a novel way to improve the UV stability of thermally modified wood has been proposed, using nano based stabilizers. But instead of coating nanoparticles on heat treated wood, wood surfaces were to be treated with nanoparticle (ZnO or CeO2) solutions, thereby forming protective envelope on a wooden surface, which could be further heat treated under controlled temperature and time.
The new system of enhancement of UV stability of thermally modified wood (NewSiest) with envelope treatment with solutions of nanoparticles represents an easy way of improvement of response of thermally modified wood to outdoor exposure parameters. This allows applications of thermally modified wood in exterior applications without the need of UV protecting surface coating layers, and so retaining the natural beauty and colour of modified wood in exterior exposure. Because thermally treated wood is an important material that can be used in buildings, the project has a significant interdisciplinary character in terms of civil engineering. EU is interested in use of sustainable materials and building with wood in terms of the circular economy concept. It is believed, that the project’s results would increase public awareness of using wood with respect to the terms of green development of the society and circular economy and as a contribution to mitigating climate change. As a consequence, increased demand for wood and wood-based products can have a positive effect on development of green economy and on economic situation of the society in general.
The general goal of this project was to develop a novel way on how to protect thermally modified wood against UV light and consequently against greying, avoiding classical UV protective formulations in a coating film. So, the main objectives were to introduce and optimise envelope treatment of wood with UV protecting nanoparticles, to set up the process of heat treatment of wood with nanoparticles in the envelope and to evaluate UV and fungal resistance of the novel wood-based material.
The new system of enhancement of UV stability of thermally modified wood (NewSiest) with envelope treatment with solutions of nanoparticles represents an easy way of improvement of response of thermally modified wood to outdoor exposure parameters. This allows applications of thermally modified wood in exterior applications without the need of UV protecting surface coating layers, and so retaining the natural beauty and colour of modified wood in exterior exposure. Because thermally treated wood is an important material that can be used in buildings, the project has a significant interdisciplinary character in terms of civil engineering. EU is interested in use of sustainable materials and building with wood in terms of the circular economy concept. It is believed, that the project’s results would increase public awareness of using wood with respect to the terms of green development of the society and circular economy and as a contribution to mitigating climate change. As a consequence, increased demand for wood and wood-based products can have a positive effect on development of green economy and on economic situation of the society in general.
The general goal of this project was to develop a novel way on how to protect thermally modified wood against UV light and consequently against greying, avoiding classical UV protective formulations in a coating film. So, the main objectives were to introduce and optimise envelope treatment of wood with UV protecting nanoparticles, to set up the process of heat treatment of wood with nanoparticles in the envelope and to evaluate UV and fungal resistance of the novel wood-based material.
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.
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.
The main expected result was improvement the UV stability of thermally modified wood using nano based stabilizers. But instead of coating nanoparticles on heat treated wood, wood surfaces were to be treated with nano dispersions, thereby forming envelope on wooden surface, which should be heat treated under controlled temperature and time.
Unfortunately, the parameters to carry out the envelope treatment were not found, but wood was classically impregnated, where protective particles were delivered into the wood structure over the entire cross section of wood specimens. On the other hand, it was shown that the unconventional thermally modified wood treatment is possible – at first impregnation and only then thermal modification in vacuum. This is in contrast to doubts of some experts in the field who were expressing concerns that metal oxide particles within the structure of wood may cause problems at thermal modification. The novel process of protective wood treatment showed to be beneficial in protection of wood against wood decay fungi.
Socio-impacts are thought to be regional and global. In Slovenia there is a company that produces thermally modified wood and protection systems for wood and application of the project’s solutions into practice may improve its market position with positive social influence (e.g. employment, taxes) in Slovenia. Globally, the projects outcomes represent a contribution to the efforts of mitigation of global climate change through potentially increased use of the carbon storage, sustainable bio-material – wood and as a contribution to the EU’s Green Deal policy.
Unfortunately, the parameters to carry out the envelope treatment were not found, but wood was classically impregnated, where protective particles were delivered into the wood structure over the entire cross section of wood specimens. On the other hand, it was shown that the unconventional thermally modified wood treatment is possible – at first impregnation and only then thermal modification in vacuum. This is in contrast to doubts of some experts in the field who were expressing concerns that metal oxide particles within the structure of wood may cause problems at thermal modification. The novel process of protective wood treatment showed to be beneficial in protection of wood against wood decay fungi.
Socio-impacts are thought to be regional and global. In Slovenia there is a company that produces thermally modified wood and protection systems for wood and application of the project’s solutions into practice may improve its market position with positive social influence (e.g. employment, taxes) in Slovenia. Globally, the projects outcomes represent a contribution to the efforts of mitigation of global climate change through potentially increased use of the carbon storage, sustainable bio-material – wood and as a contribution to the EU’s Green Deal policy.