Fiber moisture content

Fig. 7. Moisture regains of cellulose acetate (A) and triacetate (T) fibers. Moisture content on a bone-dry basis, measured at 22°C (—...

Qualitative description of the amount of drying needed to lower fiber moisture content to the optimum range or to maintain moisture content within the optimum range. 

Fiber Moisture Content, % (at 65 % R.H.-70°F Water Retention, % (Weight Change in Water) Swelling, % (Volume Change in Water)... 

Henry [27,28] was who the first started theoretical investigation of this phenomenon. He proposed a system of differential equations to describe the coupled heat and moisture diffusion into bales of cotton. Two of the equations involve the conservation of mass and energy, and the third relates fiber moisture content with the moisture in the adjacent air. Since these equations are non-linear, Henry made a number of simplifying assumptions to derive an analytical solution. 

Farnworth [14] reported a numerical model describing the combined heat and water-vapor transport through clothing. The assumptions in the model did not allow for the complexity of the moisture-sorption isotherm and the sorption kinetics of fibers. Wehner et al [30] presented two mechanical models to simulate the interaction between moisture sorption by fibers and moisture flux through the void spaces of a fabric. In the first model, diffusion within the fiber was considered to be so rapid that the fiber moisture content was always in equilibrium with the adjacent air. In the second model, the sorption kinetics of the fiber were assumed to follow Fickian diffusion. In these models, the effect of heat of sorption and the complicated sorption behavior of the fibers were neglected. 

This equation fits fiber moisture-content data over a wider range than does Fox s equation. 

Determination of fiber moisture content and fiber moisture regain... 

Table 3.2 Fiber moisture content, moisture regain, heat of wetting, and swelling of fibers in water...

Fiber Moisture content in different relative humidity of air (%) ... 

This equation indicates an important approximation being made in this analysis. Since the sheet is exposed to the humid environment, the fibers within the x-y plane on the sheet s surface will receive moisture directly. Thus, the assumption that the fibers of the sheet take up moisture at a rate given by a first order relaxation process is violated. That is, application of eq. (13) at z = 0 is an approximation and must be recognized as such. In reality, we expect the fiber moisture content q(t,z=0) to be that which is in equilibrium with c(t,z=0) i.e. 

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