Silica adhesion tension

Bartell and Flu [19] were able to determine the adhesion tension, that is, ysv -7SL. for the water-silica interface to be 82.8 ergs/cm at 20°C and its temperature change to be -0.173 erg cm K . The heat of immersion of the silica sample in water was 15.9 cal/g. Calculate the surface area of the sample in square centimeters per gram. 

Among other things, a suspension of particles will be most stable in a liquid having the highest adhesion tension for the solid. Referring to Table 40 we see that the adhesion tension for silica in water and in ani-... 

Adhesion Tension Measurements for Silica-Aqueous Solutions of LNBr. Adhesion tensions had previously been measured for such systems by Guastalla [14]. 

An aging effect for the measured force, f, was observed for the systems studied by Tenebre [26] and myself [29]. After the slide had been lifted 0.5 mm., f decreased and attained a stable value, which was used in tracing the wetting cycles (Figure 4). The adhesion tensions for the systems silica-aqueous solutions of LNBr and silica-alkaline solutions (1.2 X 10 M NaOH) of LNBr were measured at 24° C. and plotted as a function of the concentration of LNBr (Figure 5,a and b). For these systems the chemical adsorption is known (Figure 3 and Table I). 

The hysteresis of wetting (At) is low for the aqueous solutions (in distilled water), a. For the alkaline solutions, b, the hysteresis is larger but does not exceed 10 dynes. (This result was obtained for silica slides which had been soaked overnight in aqueous 4N HCl. Following this treatment the results of adhesion tension measuring became... 

Figure 5. Emersion and immersion adhesion tensions for silica-aqueous solutions of LNBr as a function of LNBr concentration in solution 24° C,...

The variation of the adhesion tension with composition of the liquid phase has been interpreted using the results obtained from chemisorption measurements of LNBr on silica, as follows. 

The constant of integration in Equation 4 was adjusted by using the average value, Tgxp, obtained from the receding and advancing adhesion tensions at c lne = 10 M. Then the calculated curve for the adhesion tension silica-aqueous solutions of LNBr is obtained (Figure 5,a). This curve verifies the experimental results satisfactorily. 

Variation of the Adhesion Tension Silica-Solution of LNBr, with Composition of Aqueous Phase... 

The free energy of adhesion or adhesion tension for the system silica-LNBr aqueous solutions has been measured. The model, which explains the above-mentioned peculiarities of the isotherm of chemisorption at the surface of the solids, is confirmed by the results of adhesion tension measurements. 

In hard-surface cleaning, solid particles deposit primarily from air suspensions and embedded in greasy soils, such as silica and metal oxides, will have their wetting characteristics modified by surfactants. Through surfactant adsorption at the water-solid particle interface, the interfacial tension will be reduced, and so will be the adhesion forces binding particles together. Efficient surfactants are anionic surfactants that, when adsorbed, make the surface of the solid particles more negative and induce electrostatic repulsion between adjacent particles [60]. 

Figure 5 Adhesion in tension vs. polymer-modified mortars with variations of polymer-cement ratio and silica fume content.

Figure 5 illustrates the adhesion in tension of polymer-modified mortars with variations of polymer-cement ratio and silica fume content. The adhesion in tension of the polymer-modified mortars is increased with an increase in the polymer-cement ratio, but decreased with raising silica fume content at the respective polymer-cement ratios. 

---