Sodium critical values

As an indication of the changes in deformation modes that can be produced in ionomers by increase of ion content, consider poly(styrene-co-sodium methacrylate). In ionomers of low ion content, the only observed deformation mode in strained thin films cast from tetra hydrofuran (THF), a nonpolar solvent, is localized crazing. But for ion contents near to or above the critical value of about 6 mol%, both crazing and shear deformation bands have been observed. This is demonstrated in the transmission electron microscope (TEM) scan of Fig. 3 for an ionomer of 8.2 mol% ion content. Somewhat similar deformation patterns have also been observed in a Na-SPS ionomer having an ion content of 7.5 mol%. Clearly, in both of these ionomers, the presence of a... 

A significant contribution of rheo-NMR has been to show that the uniform shear-rate assumption may be violated in the case of certain classes of fluids in which pathological flow properties are exhibited. Figure 2.8.10 shows shear-rate maps [26] obtained for the wormlike surfactant system, cetylpyridinium chloride-sodium salicylate in water. While the velocity gradients show no deviation from uniformity at very low shear rates, above a certain critical value yc a dramatic variation in the rate-of-strain across the 7° cone gap is found. In particular a very high shear-rate band is found to exist at the mid-gap. 

Combustion, Flames and Explosion in Gases , 2nd Editn, Academic Press, NY (1961), 322—23 (Dust quenching occurs at a critical value of the surface area of the dust per unit vol of the suspension, and depends on the nature of the salt. Better results are obtained with salts having a mp under 200°. Alkali halides are better than carbonates, potassium better than sodium, fluoride better than iodide and better than chlor-ide. If the dust concentration is high enough, even detonation waves can be extinguished)... 

In principle, all the molecular parameters in Eq. (6) can be determined independently, so that the theory can be quantitatively compared with experimental data. An example of Maxwell s construction in the dependence of x °n critical value of interaction parameter %c of charged PAAm network with the degree of ionization equals to the molar fraction of the sodium methacrylate in the chain i = xMNa = 0.012 are given in Fig. 4 (data of series D from Fig. 5). The compositions of the phases

critical value of Xc were determined by the condition that areas St and S2 defined in Fig. 4 are equal The experimental (p2e is higher and 2 determined by Maxwell s construction (Eq. 13). Thus, the experimental values of (p2e and metastable region the limits of which (p2s and (p2s are determined by the spinodal condition (two values

[Pg.182]

Fig. 6. Dependence of the extent of the collapse A and of the critical value of the interaction parameter yc on the content of sodium methacrylate xMNj (—) course determined by Maxwell s construction of data from Fig. 5 (O), ( ) experimental data. Taken from Ilavsky [11]...

Fig. 9. Dependence of the extent of the collapse A and critical values of the interaction parameter Xc on the effective degree of ionization for networks of the copolymer AAm with sodium methacrylate xMN> ( ) variously aged PAAm networks

Later, Yoshikawa and Matsubara [40] further studied a non-linear system and proposed a mechanism for the periodic behaviour that involved the formation of inverted micelles that suddenly moved to the oil phase after the concentration of adsorbed surfactants reached a critical value. They extended the experiment to a water/oil/water three-phase system in a U-shaped glass tube that gave spontaneous and stable oscillatory behaviour over a long period [41]. Since then, various characteristics of non-linear behaviour have been investigated and several mechaiusms for the non-linear behaviour have been proposed by many research groups including ours[2,5,10,42-48] however, the mechanism at a molecular level has not been clarified yet and no consensus has been achieved. The difficulty in the explanation seems to come from not only the complexity and diversity of the systems, but also limitations of the observation methods that enable us to monitor dynamic molecular behaviour at liquid/liquid interfaces with sufficient interfacial selectivity and time resolution. In this section, the TR-QELS method has been applied to the investigation of W/NB—sodium dodecyl sulfate (SDS) two-phase system [10]. 

Whole serum does not bind phenol red below a critical albumin concentration of 1.6 g%. Above this critical value, dye is bound in direct proportion to the amount of albumin in excess of the critical value. In jaundice the critical value is elevated. These results were taken to indicate that some binding sites in whole serum are occupied by, for example, bilirubin, bile acids, or fatty acids (B27). Bile salts reduce the binding of BSP (All, A14, R18a). This effect may be due to the detergent properties of bile salts because Teepol has been found to have a similar effect (A14). Binding of rose bengal was not affected by sodium dehydro-cholate or by BSP (E4). 

Fig. 7-6. Variation of particle size with relative humidity (Kohler diagram) for sodium chloride particles having different dry radii. Deliquescence occurs at 75% r.h. Note the hysteresis effect when the humidity is raised or lowered beyond the critical value. Curves for relative humidities greater than 75% were calculated. The scale above 100% is expanded. The experimental points refer to observations of Tang et al. (1977) on submicrometer-sized monodis-perse sodium chloride particles.

The determination of Ge by means of atomic absorption spectrometry (AAS) during the late 1960s was replaced by introduction of the hydride technique with sodium tetrahydroborate as a means of reduction. The detection limits indicated are 2xl0 g and 0.01 pg mL Abbasi et al. (2001) showed that there is a possibility of losing Ge in the presence of chloride when acid digestion procedures are carried out in open vessels. This is more pronounced if the Ge concentration is very low. In fact, 100 pg g can be considered as a critical value above which both open and closed vessels digestion methods can be used without any significant loss. 

Molar ratio (MR) between sulfuric acid and sodium sulfate at constant sodium sulfate concentration. The second dissociation constant of sulfuric acid is rather low, in the range of 0.01. Consequently, in a solution containing both sulfuric acid and sodium sulfate at MR < 1, substantially all the sulfuric acid reacts with the stoichiometric amount of sodium sulfate to give sodium bisulfate (buffer action). Hence, the actual concentration of free protons (H ) is directly proportional to the actual concentration of sodium bisulfate and inversely proportional to that of the unreacted sodium. sulfate. This type of dependence indicates that the actual concentration of free protons should increase quickly when MR exceeds a certain critical value (ca. 0.5). At higher MR values the current transported by the protons becomes significant at the expense of that transported by the sodium ions, and the cathodic efficiency shows a sharp decrease. 

Side effects. During chloride extraction, hydroxyl ions are formed around the reinforcing steel, locally increasing the pH and sodium and potassium ions are enriched around the steel. These changes might stimulate aUcah-silica reaction (ASR, Section 3.4). In the framework of COST 521, the possibility of ASR was checked as a side-effect of chloride extraction [28,36,80,81]. The aggregates studied were reactive and the alkali content of the cement was just below the critical values. The results obtained with non-carbonated concrete showed that, under the worst conditions, chloride extraction induced concrete expansion, but no cracking was observed. 

Crystals were grown on glass substrates by evaporating a dilute sodium chloride solution. The tip of the AFM was scanned across the surface to locate the crystals and to measure their size from the flat square top surface. The crystals were cubes up to 50 nm in size. Then, the contact force was raised to a high level and the tip was used to break the crystals from the surface. Humidity was found to be very important and was controlled to high precision in the microscope. Once the probe touched a crystal, the lateral force rose to a critical value, then fell as the cube sheared across the surface. The fracture stresses were calculated from the peak force and the crystal interface area, and plotted as a function of crystal size in Fig. 13.11(a). Two striking observations were drawn from this curve in the first place, the stress was much larger than expected for a soft material like NaCI,... 

Figures 8.4 and 8.5 indicate the critical potentials noble to which S.C.C. of 18-8 stainless steel initiates when exposed to magnesium chloride solution boiling at 130°C with and without inhibiting anion additions [27]. Anodic polarization induces shorter cracking times the more noble the controlled potential cathodic polarization, on the other hand, extends the observed cracking times. Below the critical value of -0.145 V (S.H.E.), the alloy becomes essentially immune (Fig. 8.4). Addition of various salts, such as sodium acetate, to the magnesium chloride solution shifts the critical potential to more noble values. When the amount of...

A macromolecular surfactant based on poly(acrylic acid sodium salt) (HMWSP-A2) was used to prepare LDPE dispersions. The emulsion droplet size decreased with increasing surfactant concentration up to about 20 wt% of the oil phase. The first phase inversion from a water-in-polymer-melt emulsion to a polymer-melt-in-water emulsion occurred at a critical water phase volume of 20%. After phase inversion and subsequent dilution of the emulsion, if solidification of the melt was carried out during mixing, a second phase inversion occurred and water-in-solid polymer aggregates were formed even if the phase volume of the aqueous phase was well above the critical value. These aggregates contained an aqueous phase encapsulated by the polymer. The kinetics of the phase inversions were studied and the use of the technique to obtain microcapsules from aqueous solutions was discussed. 20 refs. 

Figure 5.13 presents a gavanostatic potential transient, measured during the dissolution of an iron electrode immersed in a concentrated solution of sodium chloride. At the transition time, the Fe concentration at the anode surface reaches the critical value for precipitation of an FeCl2 film. The phenomenon leads to a sharp potential rise followed by potential fluctuations related to the behavior of the salt-film formed. The observed relation i (1/t ) is in agreement with equation (5.92). 

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