Water Adsorption fibers

Keywords Glass surface E-glass glass fiber XPS zeta-potential water adsorption. 

Figure 3 shows the water-vapor adsorption isotherms measured on the silane-treated fibers along with those obtained on the untreated fibers. A complete discussion of the water adsorption isotherms of the untreated fibers has already been reported [8]. Here, two new features are immediately evident. First, the presence of the silane overlayer has greatly enhanced the water adsorption capacity of the fibers, and, second, the silane-treated fibers that contain 4% and 6% B,0, adsorb significantly more water than the 0% B20, fibers. It is important to note that these data have been normalized to the specific surface areas of the... 

The primary effect of B,0, in the silane-treated glass fibers was found to be an enhancement of the water adsorptivity. This dependence on B203 was also observed in the water adsorption behavior of untreated fibers, water-vapor hydrated fibers, and water-leached fibers [8], but was significantly greater after the silane treatment. It was also found that the presence of B,03 influenced the amount of silane adsorption per se. Altogether it can be concluded that there is a direct effect of B,0, on water adsorption. There is also an influence of B,03 on the adsorption and condensation of aminosilane which determines the water adsorptivity of the silane-treated fiber. 

The fact that all the fibers adsorb water in excess of the expected monolayer amounts suggests that the water adsorption is multilayer in nature, or that there is pore space which is accessible to water molecules—but not accessible to the Kr used to measure the specific surface area. The XPS analyses showed that the silane overlayers increased in thickness in the 4% and 6% B,03 fibers. But the increase in water adsorptivity with % B,03 is not in direct proportion to the increase in silane overlayer thickness it is considerably larger. This suggests that B,0, has influenced the chemical and physical structure of the adsorbed silane overlayer. It is likely that there is microporosity, free volume, and/or reactive sites within the silane overlayer, in general. 

The water adsorption capacity of the silane-treated fibers—at low pressure where only the most reactive sites are sampled—was 5-10 times the specific surface area. It is proposed that the excess water adsorption capacity of the silane-treated fibers is associated with sites within the silane overlayer. These may be hydroxyls, strained siloxanes, boroxanes, free volume, or microporosity. These sites provide a mechanism for physical and chemical adsorption, swelling, and rearrangement of the adsorbed silane in the presence of water. These observations are consistent with the idea that the adsorbed silane is a chemically... 

Figure 3. Water adsorption isotherm at 298 K on heat-treated carbon fibers.

Use as Human Food. Rapeseed, as a protein source for humans, has many obstacles to overcome. The glucosinolate and fiber contents require application of new processing technology (22, 30) to eliminate antinutritional qualities. Rapeseed flours, protein concentrates, and isolates are lower in protein but higher in crude fiber and ash contents than corresponding soybean products. Rapeseed flours are comparable to soybean flour in water adsorption and give much higher fat adsorption, oil... 

The distinction between fiber saturation point (the maximum water content of swollen cell walls) and the maximum possible moisture content has a diminishing value for degraded wood, which may eventually have no effective fiber saturation point at all. The ordered and disordered cellulose in sound wood are the main sites for water adsorption (ii). As they diminish over time, their relative role in determining fiber saturation also diminishes. Nevertheless, the measurement of relative water adsorption will have some value in determining the relative degradation in a wood sample. 

Cotton and flax fibers can absorb relatively large amount of moisture that can lead to microbial attack under certain conditions of humidity and temperature. Cotton and flax may act as a nutrient, becoming suitable medium for bacterial and fungal growth. Therefore, cotton and flax fibers are treated with numerous chemicals to get better antimicrobial textiles. Additionally, many of physicochemical properties of natural fibers and composites based on fibers depend on the amounts of bound water, adsorption capacity in respect to water, and possible swelling degree. Thus, from... 

Water adsorption (g/g) by exfoliated graphite and carbonized fir fibers... 

In the case of carbonized hr fibers, water adsorption depends strongly on the type of water, as shown in Table 4.3 the fibers adsorb a relatively large amount of distilled water, but only a small amount of seawater adsorption is much more for distilled water and much less for seawater than for exfoliated graphite. Fir fibers carbonized at 900°C adsorbed a little less water than those carbonized at 380°C. After the fir fibers were saturated with distilled water, heavy oil was dropped... 

Benezet et al. (2012) reported that the addition of fibers increased the expansion index and led to a reduction in water adsorption of extruded potato starch foams. They also reported that the fiber additions at a 10% level generally improved the starch foam s properties. 

Benzophenone adsorption on samples was performed using two methods the solvent evaporation method for the case of ethanol [14], and, also, adsorption from water [15]. The former method consists in the addition of an ethanolic solution containing the probe to the previously dried powdered solid substrate, followed by solvent evaporation from the stirred slurry in a fume cupboard. In the case of water, the fibers were first swollen for at least two hours, and the addition of BZP was done by adding 500 micromoles of this probe dissolved in ethanol (saturated solution so that the added amount of ethanol was minimized). The water suspensions were kept under agitation for 24 hours and the modified cellulose (with the adsorbed BZP) was removed by filtration. From the initial 500 (xmole g of BZP, about 300 (xmole g remained into the powdered substrate (i.e., an increase in the retention capacity of the powdered substrate of about twelve times when... 

One nylon like fiber has been produced in Germany for some time based on 1,4-butanediol and hexamethylene diisocyanate. The structure resanbles nylon 6,6 except for two additional oxygens per repeating dyad. Their properties are similar except that the urethane has lower water adsorption and somewhat better electrical and mechanical stability on aging. 

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