Viscosity exponent

Absolute pressure transducers, 20 657 Absolutes, in perfumes, 18 365 Absolute system of dimensions, 8 584 Absolute temperature scale, 24 283 Absolute viscosity, exponents of dimensions in absolute, gravitational, and engineering systems, 8 584t Absorbable sutures... 

Simha and Zakin (126), Onogi et al (127), and Comet (128) develop overlap criteria of the same form but with different numerical coefficients. Accordingly, flow properties which depend on concentration and molecular weight principally through their effects on coil overlap should correlate through the Simha parameter c[ /], or cM , in which a is the Mark-Houwink viscosity exponent (0.5 < a < 0.8). If coil shrinkage, caused by the loss of excluded volume in good... 

The viscosity data for cellulose acetate [Philipp and Bjork (272) Flory, Spurr and Carpenter (707)] for three solvents at ordinary temperatures are plotted in Fig. 19. Again, although the viscosity exponents v... 

The broken line gives the hypothetical theta-solvent intrinsic viscosity, Me = KMand the gap between the solid and broken curves, therefore, represents the expansion or swelling factor a . The end effect is again seen in the deviation of the four lowest open circles from the line. It is interesting to note that if no measurements in dichloroacetic acid existed above a molecular weight of about 50,000 the viscosity exponent v would have to be chosen in the neighborhood of 0.5, even though it is clear from the complete body of data that the system is very far from the theta point ... 

Somogyi et al. (1988) measured the rate of isotope exchange at the ring nitrogen of Trp-63 of lysozyme as a function of soludon viscosity. The data were described by a modified Kramers relationship, with viscosity exponent 0.6. This is similar to what was found for the fastexchanging amide protons of lysozyme. Both processes are of low activation energy and are expected to be subject to viscous damping. 

Recently, we have observed a similar inapplicability of the SED law to a much larger molecule (benzene) in water in a high pressure NMR relaxation measurement The initial compression does not decrease but increases the rotational correlation time for a benzene molecule in water at 30 C. In other words, the viscosity exponent defined by Eq. (3) is negative at lower pressures. The exponent is turned over to a large positive at higher pressures. 

Lubricant viscosity at the inlet o< = Pressure - viscosity exponent... 

Bhattachaijee, J. K. Ferrell, R. A. (1983b). Critical viscosity exponent for a classical fluid. Phys. Rev. A, 28,2363-2369. 

Nieuwoudt, J. C. Sengers, J. V. (1989). A re-evaluation of the viscosity exponent for binary mixtures near the consolute point. J. Chem. Phys., 90,457-482. 

Effect of Fluid Viscosity. Most studies and apphcations of solid suspension occur in the turbulent regime, so the small effect of viscosity is expected. In fact, pubhshed values of the viscosity exponent range from 0 to 0.2 for experimental studies (Zwietering, 1958 Chapman et al., 1983 Ibrahim and Nienow, 1994 Rieger and Did, 1994). This suggests that the true hydrodynamic mechanism for the just suspended condition remains fuzzy. There may actually exist a hydrodynamic regime where there is little or no influence of viscosity and another where the influence is reflected in a positive value of the exponent. 

We now explain why we used only question marks into Table 1 for the critical exponent k of the sol viscosity, (Pc — p) if not stated otherwise, our discussion refers to three dimensions. (For polydisperse samples near the gel point, the concept of the ratio of the intrinsic viscosities of a branched and a linear polymer is somewhat impractical for the calculation of the viscosity exponent k. We express the viscosity contribution of each cluster size in terms of cluster radius R, cluster mass s, and cluster number Uj (normalized as number per monomer). Note that n s is the fraction of mass contained in... 

However, the picture is hardly an exact theory moreover, it was recently questioned whether the elasticity of the gel really varies with the conductivity of random resistor networks instead, the elasticity exponent was defined as y + 2j8 (which happens to be again 3 in the classical theory, but is about 2.6 in the percolation theory). Then, also the identification of viscosity with superconductor mixtures may be questionable. Even if this is not the case, entanglement effects may lead to a change in the viscosity exponent as compared to the conductivity exponent. Therefore, we use question marks instead of giving numerical predictions for k in Table 1. But Table 5 summarizes, with increasing order of reliability, the viscosity exponents determined by means of these three approximations, for both the percolation and classical theory. 

Table S. Results of various approaches to the sol viscosity exponent k...

Figure 19 illustrates the molecular weight dependence of [ /] (at zero shear rate) for PS in cyclohexane at 0 (34.5 CTC in THF at 25 C, and PHIC in 1-chlorobutane at 25 ° C. ° Hie data points for PS follow a straight line with slope 0.5 down to A4 10 while those for CTC follow a curve, which has a slope of about unity below M = 10 and weakly bends down above that M. The curve for PHIC has an inflection point at M 2 x 10. Its slope is about 1.4 around this point and decreases to 0.78 for M above 10 . The implication of this decrease in viscosity exponent is that the PHIC... 

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