Comparative Study of Two Softwood Species Industrially Modified by Thermowood® and Thermo-Vacuum Process

Abstract

Scots pine and Norway spruce, the most used commercial wood species in Europe, were thermally treated under industrial conditions by steam (Thermowood®) 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, Thermowood® 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, Thermowood® 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.

Effect of Natural Aging on Oak Wood Fire Resistance

“…According to Fengel and Wegener [ 47 ], chemical analyses of old woods show a decrease in polysaccharides and an increase in the nonhydrolyzable residues. Jebrane et al [ 48 ] explain the degradation of polysaccharides with the presence of acetyl groups that are thermally labile and lead to the formation of acetic acid, thereby causing acid-catalyzed degradation of the polysaccharides. A more reliable indicator seems to be the cellulose to hemicelluloses ratio (C/H) [ 41 ].…”

Characteristic Properties of a Bamboo-Based Board Combined with Bamboo Veneers and Vacuum Heat-Treated Round Bamboo Sticks

“…In addition to media and temperature, the heating rate and duration also affect the properties of wood and bamboo [ 24 , 25 , 26 , 27 , 28 , 29 ]. Vacuum heat treatment (VH) is a popular thermal modification method that is suitable for biomass pyrolysis, carbonization, and heat treatment of lignocellulosic materials [ 30 , 31 , 32 , 33 , 34 , 35 ]. This treatment mainly replaces oxygen with a partial vacuum, and materials are heated by forced convection.…”

“…Lin et al [ 32 ] investigated the change in chemical structure and composition of two wood species (poplar and fir) during heat treatment in a semi-industrial scale reactor in vacuum. Jebrane et al [ 34 ] and Pockrandt et al [ 35 ] evaluated the influence of steam heat treatment and VH treatment on the chemical, physical, and mechanical properties of woods. Todaro et al [ 36 ] measured the thermal properties (thermal conductivity and diffusivity) and physical properties (porosity, mass loss, and surface color) of VH-treated black poplar ( Populus nigra L.) wood.…”

The effects of tree age, thickness, and depth of timber on density and mechanical properties of heat-treated black poplar wood (Populus nigra)

“…Heat treatment improves some wood properties by decreasing moisture adsorption, PEER-REVIEWED ARTICLE bioresources.com improving dimensional stability, and increasing biological durability of wood (Akgul and Korkut 2012;Jebrane et al 2018;Kozakiewicz et al 2020). The main disadvantage of this process is the reduction of mechanical resistance depending on the type, temperature, time, rate, and atmosphere of treatment (Kubojima et al 2000;Bekhta and Niemz 2003;Hill 2006).…”