Wood sorption fractality in the hygroscopic range. Part I. Evaluation of amodified classic bet model

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 vapo r pressure range from 0.0 to 0.96 is derived and evaluated. The new model w as derived from the classic BET theory based on the assumption that the woo d internal surfaces are geometrically complex, rather than flat. The result s showed that within cell walls, the wood surface profiles and the sorbed w ater molecules organization changed under different moisture contents and t emperatures. For both desorption and adsorption at all four temperatures, n amely, 10, 25, 40, and 55 degreesC, there were at least two distinct fracta l dimensions (D < 2 and D > 2) to characterize fractality of internal wood surfaces. Fractal dimensions were larger in adsorption than in desorption f or all temperatures, except 10 degreesC, from 13% to 20% moisture content r ange.