Viscosity Zeta potential

Again the dispersants were tested on the three pigments at 70% active dosage on weight pigment in a resin-free formulation. Results are shown in Table 5 for viscosity, zeta potential, gloss, and jetness. 

Figure 9.24(a) Apparent viscosity, zeta potential, amount of adsorption, and pH in zinc oxide-water (50/50) suspensions versus initial concentration, c, curves for Na salt of polyacrylic acid (PA) (O), Na salt of formalin condensate of -naphthalene sulphonate acid (NSF) (C), and sodium tripolyphosphate ( ). The initial concentrations of PA and NSF refer to the mole concentrations expressed/monomer unit of them. A dotted line refers to the apparent viscosity versus c curve for PA at a controlled pH of 10.1. C = initial mole concentration of surfactant and polyphosphate, (b) Apparent viscosity, zeta potential, amount of adsorption, and pH in zinc oxide-water (50/50) suspensions versus initial concentration, c, curves for Na salt of formalin condensate of alkyl (C4) naphthalene sulphonic acid (Al-NSF) (Ci), sodium alkyl (C4) naphthalene sulphonate ( >), and sodium dodecyl benzene sulphonate (O). The initial concentrations of Al-NSF refer to the mole concentrations expressed/monomer unit. C = initial mole concentration of surfactant. From [61] with permission. 

Thermal diffusivity Temperature sensitivity Temperature difference Thickness of tube Aspect ratio, relation of Cp/Cy Fluid dielectric constant Wall zeta potential Dimensionless temperature Friction factor, Debye length Mean free path Dynamic viscosity Kinematic viscosity Bejan number Density... 

Electrokinetic measurements consisted of measuring the viscosity with and without NaGl (Carlo Erba, Argentine) (Figures 3-a and 3-b), while the isoelectric point (figure 2) and zeta potential (figure 3-c) were measured at different pH (HCl Ciccarelli and NaOH Tetrahedrom, Argentine). 

Electroviscous effect occurs when a small addition of electrolyte a colloid produces a notable decrease in viscosity. Experiments with different salts have shown that the effective ion is opposite to that of the colloid particles and the influence is much greater with increasing oxidation state of the ion. That is, the decrease in viscosity is associated with decreased potential electrokinetic double layer. The small amoimt of added electrolyte can not appreciably affect on the solvation of the particles, and thus it is possible that one of the determinants of viscosity than the actual volume of the dispersed phase is the zeta potential. 

As is derived from Equation (8), can be adjusted by changing the dielectric constant and/or the viscosity of the medium, but also C- As mentioned before, the zeta potential is mainly influenced by the distribution of charges at the capillary wall. All alterations resulting in a change of the charge distribution at the capillary wall like changes in the pH, ionic strength, valence of ions in the buffer electrolyte, etc., can be applied to adjust the velocity of the EOF. 

In various kinds of industrial production, materials need to be treated with charged colloidal particles. In such systems, the value of the zeta-potential analyses are needed to control production. For example, in paper, adhesive, and synthetic plastics, colloidal clay can be used as filler. In oil drilling, clay colloidal suspensions are used. The zeta potential is controlled so as to avoid clogging the pumping process in the oil well. It has been found that, for instance, the viscosity of a clay suspension shows a minimum when the zeta potential is changed (with the help of pH from 1 to 7) from 15 to 35 mV. Similar observations have been reported in coal slurry viscosity. The viscosity was controlled by the zeta potential. 

With SNF and SMF there is a correlation between zeta potential and reduction in paste viscosity [32]. 

Also with SNF and SMF, there is a correlation between dosage and zeta potential up to a maximum negative value, which corresponds to a minimum paste viscosity [33],... 

The zeta potential of the polyacrylate-based materials is significantly lower than that for SNF or SMF as shown in Fig. 2.7 [35]. In fact for a similar lowering of viscosity, the zeta potential for the polyacrylate products can be half that for SNF or SMF [36]. 

Malhotra, A., Coupland, J.N. (2004). The effect of surfactants on the solubility, zeta potential, and viscosity of soy protein isolates. Food Hydrocolloids, 18, 101-108. 

A corrected and more general analysis of the primary electroviscous effect for weak flows, i.e., for low Pe numbers (for small distortions of the diffuse double layer), and for small zeta potentials, i.e., f < 25 mV, was carried out by Booth in 1950. The result of the analysis leads to the following result for the intrinsic viscosity [rj] for charged particles in a 1 1 electrolyte ... 

In several previous papers, the possible existence of thermal anomalies was suggested on the basis of such properties as the density of water, specific heat, viscosity, dielectric constant, transverse proton spin relaxation time, index of refraction, infrared absorption, and others. Furthermore, based on other published data, we have suggested the existence of kinks in the properties of many aqueous solutions of both electrolytes and nonelectrolytes. Thus, solubility anomalies have been demonstrated repeatedly as have anomalies in such diverse properties as partial molal volumes of the alkali halides, in specific optical rotation for a number of reducing sugars, and in some kinetic data. Anomalies have also been demonstrated in a surface and interfacial properties of aqueous systems ranging from the surface tension of pure water to interfacial tensions (such as between n-hexane or n-decane and water) and in the surface tension and surface potentials of aqueous solutions. Further, anomalies have been observed in solid-water interface properties, such as the zeta potential and other interfacial parameters. 

There are a number of physical-chemical properties of emulsions that are important to consider when developing an emulsion formulation for a drug. These include, but are not limited to, particle (droplet) size, viscosity, osmolarity, and zeta potential, which are used to monitor the physical stability of emulsions. Assays of potency and degradant levels are used to monitor the chemical stability of emulsions. 

Physical stability. As indicated earlier, conventional emulsions are inherently unstable from a physical standpoint. Poor physical stability is ultimately exhibited by phase separation, which can be visually monitored. Certain properties of the emulsion will start to change long before this separation is visually apparent. An increase in particle size is particularly indicative of physical instability, since this monitors the coalescence or Locculation that is part of the process involved in ultimate phase separation. Increases in viscosity (due to Locculation) and changes in zeta potential (arising from a decrease in droplet surface area) are both indicative of poor physical stability. The presence of drug and cosolvents can potentially hasten the phase separation. 

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