The Internal Surface of Cellulosic Materials.

A review of wood thermal pretreatments to improve wood composite properties

“…The sorption characteristic of wood is quite similar irrespective of the wood species, except in woods with high extractives content (Skaar 1972). However, temperature can affect the sorption behavior of wood (Stamm 1952;Skaar 1972Skaar , 1984Hansen 1986;Kollmann and Côté 2003;Hill and Xie 2010). The sorption behavior of wood composites is different from that of gross wood (Suchsland 2004).…”

“…The degree of grindability is improved as consequence of the brittleness that torrefied wood acquires (Svoboda et al 2009), reducing energy consumption during grinding (Bridgeman et al 2010;Repellin et al 2010b;Phanphanich and Mani 2011). However, irreversible negative impacts such as loss of strength, toughness, and abrasion resistance have been reported (Harris 1952;Stamm 1956;Mayes and Oksanen 2002;Kamdem et al 2002;Tjeerdsma and Militz 2005;Shi et al 2007;Stanzl-Tschegg et al 2009;Ibach 2010). The reduction of the tenacious nature of wood during torrefaction results mainly from the breakdown of the hemicelluloses matrix and cellulose depolymerization .…”

Changes in Shrinkage and Collapse in the Wood ofEucalyptus regnansF. Muell Following Extraction

“…The relationship for all data in core 3 (hot water extraction without prior SD) also is not significant, but in core 2, which exhibited the lowest collapse levels (Table 2), S r and γ are positively correlated before (1.4%) and, much more significantly, after (0.01%) cold water extraction (Table 4a). -Importantly, whereas prior to extraction in core 2 the constant was highly significant (0.01%), after extraction it was not, thereby indicating that the regression line effectively was not different from a line describing the points and passing through zero.This suggests that in this instance the relationship between S r and γ can be described by the formula proposed by Stamm (1935Stamm ( , 1952, i.e. 8=ίρ where S = Volumetrie shrinkage, f = fibre Saturation point based on volume of water and ρ = basic specific gravity.…”

Sorption of nitrogen and water vapor on textile fibers

“…Stamm and Millett [6], after a careful co nsideration of various adsorption data on cellulose (including selective adsorp tion from solution and heats of swelling) concluded t hat all the estimated values in the li terature for the surface areas of cellulose fell into two group s. The first group was about 0.2 m 2 /g-" the microscopically visible surface"-and the other group was about 300 m 2 /g-" the surface of the transient capillary structure created within the cell walls by the swelling agents".…”

“…Willard Gibbs [29] . Tlus equation is applicable to interfaces between solid surfftces and vapors ; it was written by Gibbs as follows: Under isothermal conditions [30) and under conditions in which 1'1 is set at zero (by choosing the Gibbs boundary so that the surface concentration of the solid is zero) eq (1 ) reduces to: (2) Under appropriate conditions dp,2 may be r eplaced by its equivalent d (RT In P ) where P is the vapor pressure, and we have: (3) or (4) and (5) Where Gibbs' surface concentration 1'2 is expressed [32 , 33) as the number of moles of vapor adsorbed pel' square centimeter: q= grams of absorbate, Af= its molecular weight, and S = total surface a, rea (6 ) As u is the work requ ired to form a square centimeter of surface, it is also the free surface energy, therefore, covering the surface with a yapor lowers the value of rJ . This change of the free surface energy, which accompanies adsorption is referred to here as the free energy change of adsorption and designated t:..F as follows: t:..F= RT/MS foP q/p dp (7) The t:..F of eq (7) may be evaluated after experimental determination of S, q and P .…”