Search

The study aimed at treating metil (Sterculia appendiculata K. Schum) and neem (Azadirachta indica A. Juss) timber from Mozambique under industrial conditions by steam [Thermowood® (TW)] and vacuum [Termovuoto (TV)] thermal modifications (TM). Matched boards were treated identically and wood alterations in chemistry, colour, mass loss (ML), mechanical properties and durability were compared. The applied vacuum partly removed the acetic acid that causes carbohydrate degradation, i.e. heat applied under vacuum was less destructive. TM under vacuum generated a lighter colour than that caused by steam treatment. ML was significantly higher after the TW process namely, 14.1 vs. 9.9% after thermo-vacuum treatment for metil and 14.2 and 12.1% for neem. Colour and ML changes correlated with the decrease in shear strength, rupture and elasticity moduli and increase in wood decay resistance. Metil wood is more permeable and demonstrated significant differences between the treatments; the thermo-vacuum process was less destructive but led to less improvement of durability compared to TW treatment. [ABSTRACT FROM AUTHOR]

Scots pine and Norway spruce, the most used commercial wood species in Europe, were thermally treated under industrial conditions by steam (Thermowoo®) and vacuum (Termovuoto). Matched boards were treated, and the alterations in chemistry, color, mass loss, mechanical properties, and durability were compared. In treatments at identical temperature and duration, Thermowoo® and the thermo-vacuum process caused similar mass loss in both wood species. The thermal treatments showed minor effects on the released acetic acid during the thermal degradation of polysaccharides. The equilibrium moisture content correlated well with the mass loss and confirmed indirectly the similarity of the two processes. The chemical composition and durability of the two groups of treated wood were similar. In conclusion, Thermowoo® and thermo-vacuum treatments according to Termovuoto technology both produce similar final products with regard to chemical composition, physical-mechanical properties, and durability, with some differences in the appearance. [ABSTRACT FROM AUTHOR]