Partners and International Organizations
(English)
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A, B, HR, DK, FIN, F, D, GR, IRL, I, LV, LT, NL, N, P, RO, SI, E, S, CH, GB
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Abstract
(English)
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Wood fibres are susceptible to both variations of environmental humidity and bio-deterioration by micro-organisms, insect attacks, etc. To improve hygroscopicity and the resistance to decay wood is mostly modified chemically. These modifications are often expensive and change ecological characteristics of wood. Their manufacturing, use and elimination also can provoke environmental or health hazard. One way to modify wood without offending the ecological characteristics of wood, is through thermal treatments. This technique is known for a long time. The time of processing is usually long and heat treated wood is less strong mechanically, losing considerably its mechanical characteristics during heating. To remedy this process we have developed a process, which combines densification and Thermo-Hydro-Mechanical (THM) treatment. Depending to THM post-treatment conditions (i.e. temperature, water content and processing period) this technique can transform wood into a new material with improved mechanical properties with less hygroscopicity and increased durability. To investigate effects of THM post-treatment conditions on the densified wood elements and to study chemical changes of wood constituents during post-treatment process, a new multiparameter reactor is constructed. With this reactor one can densify and post-treat small wood elements in the same chamber under different conditions of temperature up to 200°C and humidity. More than 200 specimens were densified and post-treated. These specimens were examined by mechanical, chemical and water up take tests. Our primary results indicate that the influence of water in this process is fundamental. Water not only participates in the chemical modification of the wood constituents, but it also increases the kinetics of the transformations during the process. The influence of THM actions on densified wood for 'wood destroying fungi' is under examination.
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