Physical properties moisture effects

Other Physical Properties. In addition to its important effect on the strength of wood, moisture also affects wood s other physical properties. Moisture s effect on electrical properties was described in the section on Electrical Resistance Moisture Meters (p. 130). Other properties such as specific gravity and thermal properties are discussed here. 

In addition to time-related effects, the soUd-state physical properties are also affected by adsorbed water, which functions as a plasticizer. Water pickup is affected by the nature of the cation, with sodium ionomers absorbing about 10 times the level of the zinc equivalent (6) under the same conditions. Drying must be carried out at temperatures below 100°C and is therefore a slow process. In commercial practice, ionomers are suppUed dry, and techniques have been developed to minimize moisture absorption during processing. 

Table 6. The Effect of Moisture Content on the Physical Properties of Wool Fibers at 25°C ...

Fig. 3. Effects of composition on physical properties. A, acetyl B, butyryl C, cellulose. 1, increased tensile strength, stiffness 2, decreased moisture sorption 3, increased melting point 4, increased plasticizer compatibiUty 5, increased solubiUties in polar solvents 6, increased solubiUties in nonpolar...

Qi, P. X. and Onwulata, C. 1. (2011). Physical properties, molecular structures and protein quality of texturized whey protein isolate (WPl) Effect of extrusion moisture content. /. Dairy Sci. (Accepted for publication). doi 10.3168/jds.2010-3942. 

Nonspecific hydration, or hydration of the lattice without first-order phase transitions, also must be considered. Cox et al. [40] reported the moisture uptake profile of cromolyn sodium, and the related effects on the physical properties of this substance. Although up to nine molecules of water per molecule of cromolyn sodium are sorbed into the crystalline lattice at 90% relative humidity, the sorption profile does not show any sharp plateaus corresponding to fixed hydrates. Rather, the uptake profile exhibits a gradual increase in moisture content as relative humidity increases, which results in... 

The XRF analysis accuracy depends on physical properties of the soil, such as particle size, moisture content, homogeneity, and surface conditions. Drying, grinding, and sieving soil prior to analysis reduce the effects of these physical interferences. 

Studies in the physical properties of soil. V. The hysteresis effect in capillary properties, and the modes of moisture distribution associated therewith. Ibid., 20 97-116. 

However, for wet wood samples (H37), we observe a significant effect of the shape and of the species but without significant interaction between both factors. Energy flows are delayed for blocks 16 compared with cubes 4 and for poplar compared with beech, The effect of the lengthening of the wood blocks in the direction of the fibres as well as the effect of the species, act on the physical properties of wood samples in carbonization (decrease of the thermal conductance and of the permeability to gases). These effects could be enhanced by the moisture content of wood. 

All of the physical and mechanical properties of wood are affected by its moisture content. The effect on mechanical properties will be discussed first, followed by consideration of some other important physical properties. In all cases the discussion is limited to clear wood, free from defects such as knots. 

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