Unfrozen water content

Low resolution NMR spectrometer has been applied to determination of oil and moisture in oilseeds [79], water content in food [80], and "unfrozen" water content during freezing[81,82]. 

Unfrozen water content, UFW (g FI2O/g solids), was obtained from the relationship between latent heat of ice melting AH, J/g solids) and total water content (g/g solids) using Equation 27.1 (Laaksonen and Ross, 2000) ... 

Analysis of variance (ANOVA) was applied within a 95% confidence interval to the results obtained for water content, resistance to extension, extensibility, and unfrozen water content. 

Values of Water Content (wtot), Enthalpy, T nseu peak and Unfrozen Water Content (UFW) from Ice Melting Curves, After Freeze Cycle on DSC, of Dough According to Formulation... 

Matuda, T.G., Parra, D.R, Lugao, A.B., and Tadini, C.C. Influence of vegetable shortening and emulsifiers on the unfrozen water content and textural properties of frozen French bread dough, Lebensm. Wiss. TechnoL, 38, 275, 2004. 

R.H.M. Hatley, C. van den Berg and F. Franks, The unfrozen water content of maximally freeze concentrated carbohydrate solutions - validity of the methods used for its determination, CryoLetters, 1991, 12, 113-126. 

FIGURE 2.66 (a) Temperature dependence of unfrozen water content and (b) relationships between and changes in the Gibbs free energy of bound water for hydrated powders (C = 10 wt%) and aqueous suspensions (C =90 wt%) of different oxides. (Adapted from J. Colloid Interface Sci., 348, Gun ko, V.M., G.R. Yurchenko, Turov, V.V. et ak. Adsorption of polar and nonpolar compounds onto complex nanooxides with silica, alumina, and titania, 546-558, 2010e, Copyright 2010, with permission from Elsevier.)... 

The unfrozen water content and its dependence on the temperature and the type of soil, explains many important characteristics of freezing soil. These account for the long-term effects of freezing on natural terrain (Williams and Smith 1991) and for many of the geotechnical properties of freezing ground (Ladanyi and Andersland, 1994). 

Fig. 1.1 The unfrozen water content of various soils at temperatures below 0°C (from Williams and Smidi, 1991).

The capillary model is no longer valid therefore, below about -1°C, yet in many soils there is still much unfrozen water. This must be in the form of layers aroimd the particles (even though no discordance is seen in the dependence of suction on temperature, or of the unfrozen water content on temperature etc.). There is, for temperatures below about -1°C, a demonstrated correlation between the specific surface area of the soil (the area of particle siuface) and the unfrozen water... 

Note too, that while the unfrozen water content as a function of temperature is dependent on the soil (Fig. 1.1), the suction or stress states are independent of the type of soil. Indeed, the stress states p and are essentially described by equation 1.4, which is often known as the modified Clausius-Clapeyron equation It can indeed be derived from that purely general equation as Edlefsen and Anderson (1943) in their classic work showed (although interestingly, they concluded, wrongly, that a different variant of the equation would describe soil freezing) ... 

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