Physical properties surface tension

Some of the compounds described in this chapter were studied for specific physical properties. Surface tension measurements with solutions of 9-16 in 0.01 M hydrochloric acid demonstrated that these zwitterionic X5Si-silicates are highly efficient surfactants.21 These compounds contain a polar (zwitterionic) hydrophilic moiety and a long lipophilic z-alkyl group. Increase of the n-alkyl chain length (9-15) was found to result in an increase of surface activity. The equilibrium surface tension vs concentration isotherms for 9 and 16 were analyzed quantitatively and the surface thermodynamics of these surfactants interpreted on the molecular level. Furthermore, preliminary studies demonstrated that aqueous solutions of 9-16 lead to a hydrophobizing of glass surfaces.21... 

The physical properties of surface active agents differ from those of smaller or nonamphipathic molecules in one major aspect, namely, the abrupt changes in their properties above a critical concentration. This is illustrated in Fig. 1, in which a number of physical properties (surface tension, osmotic pressure, turbidity, solubilization, magnetic resonance, conductivity, and self-diffusion) are plotted as a function of concentration. All these properties (interfacial and bulk) show an abrupt change at a particular concentration, which is consistent with the fact that above this concentration, surface active ions or molecules in solution associate to form larger units. These association units are called micelles and the concentration at which this association phenomenon occurs is known as the critical micelle concentration (cmc). 

Murakami et al. [56] obtained correlations for hold-up and mixing time in RDCs. Fractional dead space (between 0 and 18% for their experimental data) can be predicted from the mixing time. This dead space should obviously be kept to a minimum, because polymer staying there will degrade due to secondary reactions to possibly discolored or gelled material, and product quality may be seriously harmed. Local film thickness and hold-up have been correlated to physical properties (surface tension, viscosity) and geometrical parameters [57]. Residence time distribution has been shown to become narrower when viscosity grows [58],... 

Physical or material properties surface tension as and density p... 

A number of experimental techniques by measurements of physical properties (interfacial tension, surface tension, osmotic pressure, conductivity, density change) applicable in aqueous systems suffer frequently from insufficient sensitivity at low CMC values in hydrocarbon solvents. Some surfactants in hydrocarbon solvents do not give an identifiable CMC the conventional properties of the hydrocarbon solvent solutions of surfactant compounds can be interpreted as a continuous aggregation from which the apparent aggregation number can be calculated. Other, quite successful, techniques (light scattering, solubilization, fluorescence indicator) were applied to a number of CMCs, e.g., alkylammonium salts, carboxylates, sulfonates and sodium bis(2-ethylhexyl)succinate (AOT) in hydrocarbon solvents, see Table 3.1 (Eicke, 1980 Kertes, 1977 Kertes and Gutman, 1976 Luisi and Straub, 1984 Preston, 1948). 

Pressure control by movement of liquid may not easily, and certainly won t immediately, be effected. Transport properties (viscosity, etc.), physical properties (density, etc ), and surface properties (surface tension) are so different for liquids than vapors. 

In drop/bubble experiments, either working with transient (aperiodic) procedure or with harmonic (periodic) procedure, there never is a continuous function g(t) to be analysed. There is instead a list of measurements of g(tj) for a discrete set of N time values ti, where g(t) represents the time-evolution of the inherent interfacial physical and geometrical properties (surface tension, differential pressure, interfacial area, et cetera). 

Several of the physical properties of a liquid depend on the magnitude of its intermolecular forces. In this section we consider three such properties surface tension, viscosity, and vapor pressure. 

Revised material in Section 5 includes an extensive tabulation of binary and ternary azeotropes comprising approximately 850 entries. Over 975 compounds have values listed for viscosity, dielectric constant, dipole moment, and surface tension. Whenever possible, data for viscosity and dielectric constant are provided at two temperatures to permit interpolation for intermediate temperatures and also to permit limited extrapolation of the data. The dipole moments are often listed for different physical states. Values for surface tension can be calculated over a range of temperatures from two constants that can be fitted into a linear equation. Also extensively revised and expanded are the properties of combustible mixtures in air. A table of triple points has been added. 

It would clearly be desirable to extend the scope of the Kelvin method to include a range of adsorptives having varied physical properties, especially surface tension, molar volume, molecular shape and size. This would enable the validity of the method and its attendant assumptions to be tested more adequately, and would also allow a variation in experimental technique, for example by permitting measurements at 298 K rather than 77 K. 

Properties. The physical properties of aHphatic fluorine compounds containing chlorine are similar to those of the PECs or HECs (3,5). They usually have high densities and low boiling points, viscosities, and surface tensions. The irregularity in the boiling points of the fluorinated methanes, however, does not appear in the chlorofluorocarbons. Their boiling points consistently increase with the number of chlorines present. The properties of some CECs and HCECs are shown in Tables 3 and 4. 

Because the reaction takes place in the Hquid, the amount of Hquid held in the contacting vessel is important, as are the Hquid physical properties such as viscosity, density, and surface tension. These properties affect gas bubble size and therefore phase boundary area and diffusion properties for rate considerations. Chemically, the oxidation rate is also dependent on the concentration of the anthrahydroquinone, the actual oxygen concentration in the Hquid, and the system temperature (64). The oxidation reaction is also exothermic, releasing the remaining 45% of the heat of formation from the elements. Temperature can be controUed by the various options described under hydrogenation. Added heat release can result from decomposition of hydrogen peroxide or direct reaction of H2O2 and hydroquinone (HQ) at a catalytic site (eq. 19). 

The principal physical properties influencing ink performance ate surface tension and viscosity. High surface tension is desired for good droplet formation and capillary refill in dtop-on-demand ink jet. Low viscosity is desired because less energy is required to pump and eject ink. Conductivity is also an important parameter. Continuous ink-jet inks must have some conductivity to allow for charging. Low conductivity is generally preferred for impulse, particularly thermal ink jet, because excess ions can cause corrosion of the printhead. 

Spray Correlations. One of the most important aspects of spray characterization is the development of meaningful correlations between spray parameters and atomizer performance. The parameters can be presented as mathematical expressions that involve Hquid properties, physical dimensions of the atomizer, as well as operating and ambient conditions that are likely to affect the nature of the dispersion. Empirical correlations provide useful information for designing and assessing the performance of atomizers. Dimensional analysis has been widely used to determine nondimensional parameters that are useful in describing sprays. The most common variables affecting spray characteristics include a characteristic dimension of atomizer, d Hquid density, Pjj Hquid dynamic viscosity, ]ljj, surface tension. O pressure, AP Hquid velocity, V gas density, p and gas velocity, V. ... 

Physical Properties. Sulfur dioxide [7446-09-5] SO2, is a colorless gas with a characteristic pungent, choking odor. Its physical and thermodynamic properties ate Hsted in Table 8. Heat capacity, vapor pressure, heat of vaporization, density, surface tension, viscosity, thermal conductivity, heat of formation, and free energy of formation as functions of temperature ate available (213), as is a detailed discussion of the sulfur dioxide—water system (215). 

Vinyl acetate is a colorless, flammable Hquid having an initially pleasant odor which quickly becomes sharp and irritating. Table 1 Hsts the physical properties of the monomer. Information on properties, safety, and handling of vinyl acetate has been pubUshed (5—9). The vapor pressure, heat of vaporization, vapor heat capacity, Hquid heat capacity, Hquid density, vapor viscosity, Hquid viscosity, surface tension, vapor thermal conductivity, and Hquid thermal conductivity profile over temperature ranges have also been pubHshed (10). Table 2 (11) Hsts the solubiHty information for vinyl acetate. Unlike monomers such as styrene, vinyl acetate has a significant level of solubiHty in water which contributes to unique polymerization behavior. Vinyl acetate forms azeotropic mixtures (Table 3) (12). 

The excellent chemical resistance and physical properties of PVA resins have resulted in broad industrial use. The polymer is an excellent adhesive and possesses solvent-, oil-, and grease-resistant properties matched by few other polymers. Poly(vinyl alcohol) films exhibit high tensile strength, abrasion resistance, and oxygen barrier properties which, under dry conditions, are superior to those of any other known polymer. The polymer s low surface tension provides for excellent emulsification and protective coUoid properties. 

Important physical properties of catalysts include the particle size and shape, surface area, pore volume, pore size distribution, and strength to resist cmshing and abrasion. Measurements of catalyst physical properties (43) are routine and often automated. Pores with diameters <2.0 nm are called micropores those with diameters between 2.0 and 5.0 nm are called mesopores and those with diameters >5.0 nm are called macropores. Pore volumes and pore size distributions are measured by mercury penetration and by N2 adsorption. Mercury is forced into the pores under pressure entry into a pore is opposed by surface tension. For example, a pressure of about 71 MPa (700 atm) is required to fill a pore with a diameter of 10 nm. The amount of uptake as a function of pressure determines the pore size distribution of the larger pores (44). In complementary experiments, the sizes of the smallest pores (those 1 to 20 nm in diameter) are deterrnined by measurements characterizing desorption of N2 from the catalyst. The basis for the measurement is the capillary condensation that occurs in small pores at pressures less than the vapor pressure of the adsorbed nitrogen. The smaller the diameter of the pore, the greater the lowering of the vapor pressure of the Hquid in it. 

Solders should flow promptly and smoothly over the surfaces of the parts to be joined. This property depends on the surface tension, viscosity, and adhesive properties of the molten solder. Finally, the color of a solder should match that of the metal employed, and its physical properties should be at least as good as those of the metal, in order for the joint not to be a source of weakness (150). 

An overview of some basic mathematical techniques for data correlation is to be found herein together with background on several types of physical property correlating techniques and a road map for the use of selected methods. Methods are presented for the correlation of observed experimental data to physical properties such as critical properties, normal boiling point, molar volume, vapor pressure, heats of vaporization and fusion, heat capacity, surface tension, viscosity, thermal conductivity, acentric factor, flammability limits, enthalpy of formation, Gibbs energy, entropy, activity coefficients, Henry s constant, octanol—water partition coefficients, diffusion coefficients, virial coefficients, chemical reactivity, and toxicological parameters. 

Parachor is the name (199) of a temperature-independent parameter to be used in calculating physical properties. Parachor is a function of Hquid density, vapor density, and surface tension, and can be estimated from stmctural information. Critical constants for about 100 organic substances have been correlated to a set of equations involving parachors and molar refraction (200). 

Effect of Physical Properties on Drop Size Because of the extreme variety of available geometries, no attempt to encompass this variable is made here. The suggested predictive route starts with air-water droplet size data from the manulac turer at the chosen flow rate. This drop size is then corrected by Eq. (14-195) for different viscosity and surface tension ... 

Physical characteristics Molecular weight Vapour density Specific gravity Melting point Boiling point Solubility/miscibility with water Viscosity Particle size size distribution Eoaming/emulsification characteristics Critical temperature/pressure Expansion coefficient Surface tension Joule-Thompson effect Caking properties... 

The physical properties of saturated fluorocarbons and their analogous hydrocarbons differ in many respects [4 5] Sahirated fluorocarbons have the lowest dielectric constants, surface tensions, and refractive indexes of any liquids at room... 

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