Minimum water content

Different soil types have differing field capacities and minimum water contents. 

Soil type Field capacity Minimum water content... 

Very similar results are obtained with ethanol-water mixtures109. Presumably the ester can only be protonated if some minimum number of water molecules is available to solvate it, and a point is reached where the minimum water content of the immediate solvation shell of the protonated ester is greater than that of the medium as a whole. Beyond this point, which apparently corresponds quite closely to an average solvent composition of two water molecules to one of dioxan, this minimum water content must be acquired at the expense of the solvent at large, and thus of a slightly less favourable entropy term however, the enthalpy of activation should remain approximately constant as long as there is sufficient water in the solvent for this selective solvation110 to be possible. 

Suspension films separating two solid surfaces, and Wetting films separating a solid or liquid from a vapour. The minimum water content for which a small sample of soil or similar material will barely flow in a standardized test method. Also termed the upper plastic limit . See also Atterberg Limits, Plastic Limit, Plasticity Number. Light non-aqueous phase liquid. See Non-aqueous Phase Liquid. 

Figure 4.2 shows the water content of carbon dioxide for four isotherms. The experimental data come from several sources hence the number of different points. The calculations are from AQUAlibrium. The minimum in the water content of the gas can be seen clearly in this plot. For example, at 50°C the minimum water content occurs at about 8.5 MPa, which is a water content of about 0.33 mol%. 

Diffusion of Components. The diffusion process was investigated in the following manner W/0 microemulsions with a minimum water content were carefully layered on top of water in amounts to give a final composition of a W/0 microemulsion with a maxiumum water content. 

The minimum solubility of water In a W/0 mlcroemulslon stabilized by an Ionic surfactant/medium chain length cosurfactant combination depends on the surfactant counter Ion Figure 1 shows a typical solubility curve (19). The reason for this minimum water content Is related to the water of hydration and calculations of the free energy of gaseous water/surfactant aggregates (20) are useful In order to understand the fundamental basis of the phenomenon. 

Figure 1. The solubility of an Ionic surfactant (S) In a cosurfactant (CoS, pentanol) Is proportional to a minimum water content.

In fact, the surfactant monomeric aggregates and the polymer are mutually exclusive In the range of minimum water content according to the following results. The minimum water content In weight percent. Figure 4, may be expressed as... 

In which W Is minimum water content In weight percent, S Is the surfactant content, also In weight percent while a and b are constants. For the system with pentanol and sodium dodecyl surfate a 0.5 and b - 0.207. 

One Interesting feature Is that the minimum water content to dissolve the surfactant was unchanged, but the maximum Increase of water content with added surfactant was reduced. 

For a given object, the permissible rate of drying can be affected by viscosity of water which depends on temperature. The rate of surface evaporation, which can be controlled over a wide range by humidity, temperature and flow velocity of the air, must not exceed a critical limit, beyond which the rate of evaporation would exceed the rate at which water is supplied from deeper layers. The effect of temperature and air humidity on the distribution of water in the object being dried is illustrated in Fig. 171. The diagram indicates that the drying will proceed at the highest rate and at a minimum water content difference (and thus minimum stress) in case c which corresponds to the conditions in controlled humidity dryers. 

HFC water-polymer solution, minimum water content 35%,... 

Prior to liquefaction, air is dried by contacting it with dry silica gel adsorbent. The air entering the dryer with 0.003water/kg dry air must be dried to a minimum water content of 0.0005 kg/kg dry air. Using the equilibrium data below, calculate the kg gel per kg dry air required for the following. 

The threshold porosity so in the Bruggeman correction is defined by specifying a minimum water content X m with sq = e(X , ). Here X in is the minimum amount of water that must be sorbed by the membrane for the pore liquid phase to be sufficiently well connected to allow for transport through the membrane. Examining the conductivity data in Figure 4.1, it is clear that Xmin should lie somewhere between 1.5 and 2, since this is the approximate range where the conductivity bounds intersect the x-axis. 

The minimum water content A , was chosen such that the model conductivity threshold closely matches the data of Sone et al. A reasonable order of magnitude for Dxi was chosen from a literature survey, and Ax, Ai, s, and Z>12 were then varied such that the BFCM results lay within the error bounds for all A. 

When thus we draw in such a diagram a tangent at this angle to the coacervate branch the point of contact indicates that coacervate which has the minimum water content. 

One would indeed expect for the shape of the A + G curves in the figure curves which possess steeply rising branches on both sides and have a top (maximum dry weight, that is to say, minimum water content) at the equivalence point (arrows in the figure). 

The minimum water content in the isohydric series of mixtures thus lies to the left of the equivalent mixing proportion, i.e. at mixtures which are relatively poorer in gum arabic. 

Concrete comes in many compositions with a number of different aggregate compositions and water fractions, drying as it ages. At the H ord site, the normal aggregate is basalt and contains little carbon. The water fraction in, Haiiford concrete used in critical mass laboratory (CMti) experiments has been analyzed as high as 11 wt% (Ref. 1). The minimum water content is the water of hydration (6 wt%). 

The acetone to be used for freeze-substitution must have the minimum water content possible. 1-2% water content will prevent substitution (11). 

The first requirement imposed on high performance concretes (HPC) of any kind is their good workability, and this property should be obtained with minimum water content to avoid all possible negative effects of additional water over that necessary for cement hydration, such as bleeding, segregation, difficulties in correct placing in the moulds, etc. On the other side, excess cement is also unacceptable to control shrinkage and creep. 

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