Processi e tecniche di trattamento eco-compatibili per il miglioramento delle proprietà legno

Responsabili di progetto

Marco Togni, Hektor Thoma

Accordo

ALBANIA - MoES - Ministry of Education and Sport of the Republic of Albania

Bando

CNR/MOES biennio 2018-2019 2018-2019

Dipartimento

Scienze bio-agroalimentari

Area tematica

Scienze bio-agroalimentari

Stato del progetto

Nuovo

Proposta di ricerca

Summary:
The project proposal have the purpose to promote advanced eco-friendly treatment methods for wood and wood products, which allow better performances and low environmental impact, to enhance the availability of new products and the competitiveness of small and medium enterprises (SME).
The current needs of enhancing wood properties, e.g. wood stability, durability and more generally aesthetics is typically achieved with some chemical answers. Different kinds of chemical treatments can give the expected results, but with the added high environmental impacts in terms of non-renewable resources consumption (petroleum and derivatives), end-of-life disposal costs, negative environmental impacts.
The heat treatment of wood is a method offering some quality solutions, alternative to those ones using chemicals; through some low impact technologies, by means of the accurate use of high temperature, in combination with controlled humidity and pressure it is possible to treat full size timber (e.g. plank and lumber) to enhance wood stability (reducing the hygroscopic properties of wood), its durability (removing any susceptibility to Insect attack, highly reducing the sensibility to decay by fungi) and aesthetics (reducing the color variability, due to the tint homogenizing, shifting the color darker as to use European wood instead of exotic one).
The laboratories of the research units involved in this project are already basically equipped to test some innovative heat treatment processes to be implemented on different most used wooden species (e.g. beech - Fagus sylvatica, white fir - Abies alba, sweet chestnut - Castanea sativa) and extended to other species also for the improvement of low-quality raw-timber for the production of innovative and added-value products.

Methodology:
In Albanian laboratories the vacuum high temperature treatment will be studied, because it has a positive approach to the environment. The tests will be based on small size specimens, originated as from broadleaves as from coniferous species, present in both countries. For heat treatments will be used vacuum oven dry and an autoclave (maximal heating temperature up to 300°C), where it is possible to generate a vacuum up to 1 atmosphere. The treatment temperature will range from 150°C up to 250°C, changing the negative pressure till values which can make possible the heat transfer. The treatment duration will be specific for each air temperature and will be measured from the moment when temperature will become constant until the beginning of the cooling phase. A series of treatments with various parameter combinations will be performed. Some treatments will be carried out with natural vegetal oil soaked samples.
In Italian laboratories, through the available equipments (all the laboratory LABESS-IVALSA equipments, the University laboratory - autoclave max temperature 280°C and max pressure 8 atm - ), some tests at high pressure will be performed on some of the species indicated (e.g. beech, fir, etc.).
After treatments, some physical and mechanical characteristics will be studied according to European and International Standards (e.g. mass loss, equilibrium moisture content, total swelling and shrinkage, hardness, MOE, MOR, compression strength). By means of a statistical analisys the results will be studied to find some proposals which could be implemented in a sort of standardized treatment system which could ne applied at a industrial scale (at the level of SME).

State of the art, researcher experiences:
Heat treatment is a process widely used to enhance wood properties. Because heat treatment involves a large number of variables such as temperature, pression, time, type of atmosphere and treatment sequence, a large number of methods were developed over the years, and a large number of researches are still going on in order to get a better understanding of the reactions involved. According to this, many treatment technologies are actually available on the market and the general principles of wood thermal degradation are well documented. The whole field of high temperature (HT) processing of wood was subjected to large review papers, trying to make the point on the different properties modification affects. HT modification of wood can be performed on different base materials (softwood, hardwood or wood derivatives), starting from different moisture contents (from anhydrous to saturated), at different temperatures, with different heat diffusion mediums (CO2, N2, Air, heating plates, oil, saturated vapour and overheated vapour), at different pressures and for different treatment periods. The treatment intensity is related to the modification of some wood properties such as mass loss, colour, chemical transformation, anatomical effects, mechanical performances, dimensional stability, equilibrium moisture content, durability and wettability. Treatment intensity should always be expressed as dry mass loss. This parameter in fact takes into account the degradation of the cell wall and it is the only one able to allow comparison between different processes.

Albanian and Italian research teams have a good knowledge and experience on this subject. They were started working on the wood modified products by means of HT, made from national wood species respectively since 2007 and 2010. They know very well the actual technology in the countries and problems dealing with the market as well as good collaboration with native wood processing industry. Through consulting and standardization, each department has built some useful contacts with the timber companies, industry and trade enterprises, and they are working to increase the attention of the private subjects concerning the evolution of these new eco-friendly wood based products.

Obiettivi della ricerca

The proposed research has a wide range of purposes, which could lead to some direct results:
- Advanced wood treatment methods may get innovative, added-value and low environmental impacts products, also with low-quality raw-timber.
- Find out the more suitable treatment methods according to the studied properties
- The improvement of wood properties and performances, particularly in hygroscopic stability and in durability.
- Improvement of appearance quality (homogeneity and colour).

Among all the aims, some important secondary results of the research must be expected:
- Develop the use of HT wood, instead of chemical treated wood.
- Help to know and to spread the use of correct methods of heat treatment.
- Improvement of local wood processing technology and also implement the quality control procedures, in relation to HT wood.
- Increase the competitiveness of wood SME.
- Contribute to a low-impact economy.

And also, more generally:
- Use in a better way the limited forest resources.
- Better evaluation of rough timber, actually without any interest for industry, and used principally as fire-wood.
- Increasing the market of wood material, reducing the wood products import.

In connection to project participants:
- Improvement of scientific research work in both Departments.
- Higher collaboration between partners institutions and the sector of production.
- Positive perspectives in the framework of European research programmes for AL - IT joint projects.

Ultimo aggiornamento: 19/04/2024