Viscosity vs. concentration

Fig. 3. Solution viscosity vs concentration for ethylene oxide polymers (10). The molecular weight of the polymer is indicated on each curve. The dependence of the intrinsic viscosity [Tj] on molecular weight M for these polymers can be expressed by the Mark-Houwink relationship ...

Figure 7 shows the viscosity vs. concentration curves for PTF in various organic solvents. As would be expected, in toluene, the most polar among the four solvents, the viscosity was the lowest at any given concentration. Figure 8 shows the effect of concentration on the viscosity of C02 at 25°C. The observed 50% increase in viscosity is not sufficient for enhanced oil recovery operations. 

Figure 7. Viscosity vs. concentration curves for PTF in various solvents at 25°C. The number near each point...

Fig. 56. Dependence of Mwof the microgels on the polymer yield in the anionic polymerization of EDMA in toluene by n-BuLi [254] (see Figure 53 caption for the reaction conditions). Reduced viscosity vs concentration of microgels a) Composition (mol %) N,N -methyl-enebisacrylamide (55%), methacrylamide (33%), methacrylic acid (2%), methacrylamido acetaldehyd-dimethylacetal (10%),measured at 20 °C in water, b) Composition (mol %) 1,4-DVB (35%), propenic acid amide-2-methyl-N-(4-methyl-2-butyl-l,3-dioxolane prepared by emulsion copolymerization and measured in dimethylformamide.

Prepare a carboxymethylcellulose solution as in Part A. Prepare dilutions to bracket the suspected concentration in the unknown. Measure the viscosities of the solutions and the sample with a rotational viscometer and in a constant temperature bath set at 25°C. Plot viscosity vs. concentration and determine the concentration in the unknown. 

Solvent viscosity vs, concentration plots for cellulose dissolved in TFA-CH2CI2 (70/30, v/v) do not exhibit a maximum (1I,S1) in contrast to the typicid behavior of polymer liquid crystal solutions. This same behavior is exhibited by other cellulose-solvent systems (52,fiQ). Conio et al. (59) si gest that due to the close proximity of the cholesteric mesophase to its solubility limit, it is only observed in a metastable condition. 

Fig. 1. Representative plots of the reduced viscosity vs concentration for polyelectrolytes and non-polyelectrolytes...

Fig. 5.7. Characteristic molecular weight for the viscosity vs concentration for the polyisobutylene-toluene system. The open circles (O) were obtained from >/0 vs c at constant molecular weight (159) the open squares ( ) were obtained from >/0 vs Mw at constant concentration (159) the solid square ( ) was obtained on undiluted polyisobutylene (9)...

Fig. 3. Solution viscosity vs concentration for ethylene oxide polymers (10). The molecular weight of the polymer is indicated on each curve.

The authors observed that the formation of aggregates of polyazophenylene is very dependent on the flexibility of the polymer matrix. Poly(azophenylene-b-styrene) fails to exhibit both a maximum in their viscosity vs concentration functions and also an U V maximum at 580 nm. In contrast, the flexible diene matrix favours aggregation, and the resulting, strong intermolecular n-electron interactions lead to a considerably... 

FIG. 16.28 Viscosity vs. concentration of 50/50 copolymer of n-hexyl and n-propylisocyanate in toluene at 25 °C. From Aharoni (1980) Courtesy of John Wiley Sons, Inc. 

Second, the spatially periodic model suggests further interpretations and experiments. That no kink exists in the viscosity vs. concentration curve may be related to the fact that the average dissipation rate remains finite at the maximum kinematic concentration limit, ma>. Infinite strings of particles are formed at this limit. It may thus be said that although the geometry percolates, the resulting fields themselves do not, at least not within the context of the spatially periodic suspension model. 

Figure 11. Relative viscosity vs. concentration behavior for suspensions of spheres having narrow size distributions. Particle diameters range from 0.1 to 440 pm. (Reproduced with permission from reference 30. Copyright 1965...

Xanthan forms the most pseudoplastic (instantaneous, reversible shear thinning) solutions of all the gums. This property is due to the stiffness of its molecules and/or intermolecular associations of two or more molecules. In plots of viscosity vs. concentration, there is a Newtonian (non-pseudoplastic) plateau at very low shear rates, which at least, makes its solutions appear to have a yield value (a yield value being the force required to initiate flow). As a result, xanthan is an excellent stabilizer for suspensions and emulsions. 

Figure 11. Reduced viscosity vs. concentration relationships of PS and sulfonated polystyrene with different sodium sulfonate levels in tetrahydrofuran. (Reproduced with permission from reference 114. Copyright 1982 Wiley.)...

Still, there is the most interesting phenomenon that the cationic polymer poly(iV-hexadecyl-/V,/V-dimethy-N-vinylbenzyl ammonium chloride) 28 exhibits very low reduced viscosities but does not show polyelectrolyte behaviour in aqueous solution [103, 292] the plot of reduced viscosity vs concentration is strictly linear, and is insensitive to added salt (Fig. 20). Importantly, this head type vinyl polymer without main chain spacer is not water-soluble and thus not a true polysoap, but forms only metastable aqueous solutions (see Sect 2.2.4). Similar results were reported for alkylated poly(vinylimidazoles) such as 26 [347], It may be speculated that such solutions represent rigid molecular latexes rather than flexible polymeric micelles , and further studies on such systems would be most interesting. 

It should be noted that the Doi and Ohta theory predicts oifly an enhancement of viscosity, the so called emulsion-hke behavior that results in positive deviation from the log-additivity rule, PDB. However, the theory does not have a mechanism that may generate an opposite behavior that may result in a negative deviation from the log-additivity rule, NDB. The latter deviation has been reported for the viscosity vs. concentration dependencies of PET/PA-66 blends [Utracki et ah, 1982]. The NDB deviation was introduced into the viscosity-concentration dependence of immiscible polymer blends in the form of interlayer slip caused by steady-state shearing at large strains that modify the morphology [Utracki, 1991]. 

Table 7.9. Parameters used for curve fitting of viscosity vs. concentration data to Equations 7.9, 7.123 and 7.125 [Utracki, 1991]...

Viscosity measurements were also performed to complement the DLS data. The [r ] values for the zwitterionic samples are considerably higher than those for the amine-capped samples and the reduced viscosity vs concentration plots are not always... 

Figure 10. Viscosity vs. concentration relationship of PS-7 ( ) PS-7 (H) xanthan gum Brookfield LVT Viscometer, 60 rpm...

Figure 4, Reduced viscosity vs. concentration (A) polymer 4b in Hp (B) Na salt of polymer 4b in 5% NaCl aqueous solution (C) polymer 4a in HjO at 30° C...

FIGURE 13.2 Bulk viscosity vs. concentration of PPTA-H2SO4 solution. (From Bair, T.I. and Morgan, P.W., U.S. Patent 3,673,143, 1972 U.S. Patent 3,817,941, 1974. With permission.)... 

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