Wood Sorption Fractality in The Hygroscopic Range. Part I. Evaluation of A Modified Classic Bet Model

Bingye Hao, Stavros Avramidis

Abstract


A new model for determining the fractal dimension (D) of the internal cell-wall surfaces of klinki pine by using sorption isotherms at a relative vapor pressure range from 0.0 to 0.96 is derived and evaluated. The new model was derived from the classic BET theory based on the assumption that the wood internal surfaces are geometrically complex, rather than flat. The results showed that within cell walls, the wood surface profiles and the sorbed water molecules organization changed under different moisture contents and temperatures. for both desorption and adsorption at all four temperatures, namely, 10, 25, 40, and 55°C, there were at least two distinct fractal dimensions (D < 2 and D > 2) to characterize fractality of internal wood surfaces. Fractal dimensions were larger in adsorption than in desorption for all temperatures, except 10°C, from 13% to 20% moisture content range.

Keywords


Water;sorption;isotherm;fractal model;internal surface;clusters

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