Dynamic water vapour sorption properties and dimensional stability of thermally and acid-treated Scots pine (Pinus sylvestris L.)

• In order to accelerate the thermal modification process, Scots pine sapwood samples were subjected to two types of treatments. One group of samples was impregnated with water and exposed to 220oC and the second group was initially treated with low concentration of acids (1 mol l-1 AlCl3 and a mixture of 0.5 mol l-1 H2SO4 and 1 mol l-1 AlCl3), and then heated at different temperatures (180 and 120oC) to achieve comparable mass loss (ML) levels. The water vapour sorption isotherms of the thermally and acid-treated wood samples were determined using a dynamic vapour sorption (DVS) apparatus. Increasing the temperature in both thermally and acid-treated samples resulted in ML attributable to hemicelluloses degradation. As a result thereof, dimensional stability and reduction in the hygroscopicity of wood were observed. Acid-treated samples heated at lower temperature exhibited similar water sorption behaviour as water-treated samples subjected to considerably higher temperature. The sorption data were analysed using the Hailwood-Horrobin (H-H) and excess surface work (ESW) models. The data indicated that the monolayer and polylayer sorption were reduced by the acid and thermal treatments, but acid treatment reduced the monolyer sorption stronger than the thermal. The effect of thermal and acid treatments on the flexibility of the cell wall matrix could not be fully distinguished.

Subject headings

LANTBRUKSVETENSKAPER  -- Lantbruksvetenskap, skogsbruk och fiske -- Trävetenskap (hsv//swe)

AGRICULTURAL SCIENCES  -- Agriculture, Forestry and Fisheries -- Wood Science (hsv//eng)

Keyword

sorption isotherms

EMC

hysteresis

thermal treatment

acid-heat treatment

DVS

Forestry and Wood Technology

Skog och träteknik

Forestry and Wood Technology

Skog och träteknik

Publication and Content Type

ref (subject category)

kon (subject category)