Dynamic viscosity comparisons

A comparison with cross-linker 4a proves the underlying dynamics are controlled by metal-ligand dissociation. Ligand exchange kinetics for 4a are substantially faster than for 4b but the association thermodynamics are very similar, and the effect of those kinetics is dramatic. At 5% cross-linker, the dynamic viscosity of lOOmgmL 4a-PVP is only 6.7 Pa s, a factor of 80 less than that of the isostmctural network 4b PVP. Although the association constants are not identical, the effect of the thermodynamics would be to increase the viscosity of 4a PVP relative to 4b PVP, the opposite direction of that observed. The kinetics dominate even the extent of cross-linking 5% 4a PVP is less viscous by a factor of 5 than is 2% 4b PVP. 

Fig. 8.1. Dynamic viscosity t] (a>) and steady state viscosity f](y) for undiluted narrow distribution polystyrenes. The data are plotted in reduced form to facilitate comparison. The dimensionless shear rate or frequency is t]0Mwy/gRT >r r/ M co/gRT. [See Eq.(8.3)]. The dynamic viscosities are for Mw = 215000 (O) and Mw = 581000 ( ) at 160° C (312). The steady shear viscosity is for Mw = 411000 (A) at 176° C (313). The shapes in the onset region are similar for the three curves, but the apparent limiting slope for the dynamic...

Based on our experiments such substitute has been found. The exact specification on the substitute is know-how of the Institute of hydromechanics National Academy of Sciences of the Ukraine at Kiev. The comparison of measured values of dynamic viscosity of the methanol solution substitute and the data available in the literature for real methanol solution are presented in Figure 3 (the value C is the weight concentration of methanol in a solution). Since the measurements were realised within the temperature range T = 18-20°C, a fairly good agreement between methanol and its substitute was proved. Of course, to use the substitute is not limited on this temperature range it should be used also for very low temperatures. The preliminary measurements with the substitute used as the carrier fluid also confirmed results illustrated in Figure 1. 

Figure 3. Comparison of dynamic viscosity p of a real water-methanol solution and its...

Kraus has studied the steady flow and dynamic viscosity of the following branched butadiene t) ene block copolymers (88)3, (88)3, (88)4 in comparison with 888 and 888 copolymers. He has found higher viscosities (at constant molecular weight and total styrene content for polymers terminated by styrene blocks) for the former inespective of branchii, but for copolymers of equal molecular weight the viscosity is smaller for branched than for linear copolymer. Kraus has also studied the effect of free polybutadiene molecules on the viscoelastic behaviour of branched (88)4 block copolymers which consist of styrene domains in a butadiene matrix and verified De Gennes s theory of reptation ... 

By comparison of the dynamic viscosity expressions without and with internal viscosity [see Eqs. (3.1.15) and (3.3.16), respectively], we see that in the former case the sum tends to zero for large co, unlike in the latter we conclude that in the presence of internal viscosity the dynamic viscosity deviates from what is commonly regarded as a general law. The reason lies in the fact that with internal viscosity the intramolecular tension contains a contribution depending on x h,t), unlike the other models where it depends on the elastic force only, that is, on x h,t). 

The analyzed fluids at shear rates 30 — 2.2 x 10 s showed the properties of a Newtonian fluid. The comparison of dynamic viscosity experimental values ( /exp) obtained by us with the values calculated by the additive law showed significant negative deviation of experimental dynamic viscosity values from the design parameters, reaching 75% at 20 °C and 440% at -20 °C (see Table 2). 

The pressure losses of electric separators in comparison with the other types are very low, ranging between 60 and 250 Pa. A good separation efficiency with saving optimum operation conditions may be achieved in mechanical dry separators as well as wet separators at pressure losses of 600 to 1200 Pa (except for Venturi and slot separators). Considerable pressure losses occur in the filtration layer. Their values depend on the layer porosity , diameter of filtration material fibres, layer thickness, gas dynamic viscosity and the velocity of the streaming gas. 

Small amplitude dynamic viscoelastic properties of apple butter, mustard, table margarine, and mayonnaise were compared to their respective properties in steady shear flow in the range of shear rates and frequencies of 0.1 to 100 sec" (Bistany and Kokini, 1983). Comparisons of dynamic and steady viscosities showed that dynamic viscosities (tj ) are much greater than steady viscosities (17). Consequently, the Cox-Merz rule is not obeyed (Bistany and Kokini, 1983). This phenomenon can be explained by a signifi-... 

Fig. 14. Comparison of the steady shear viscosity and the dynamic viscosity versus angular frequency or shear rate.

Figure 23 Relative viscosity vs. time for a typical TGDDM-DDS system during a dynamic test comparison between experiment data (points) and model predictions (ral lines). (After Kenny et al., ref 2).

Figure 2.17 Comparison of near-critical dynamic viscosity data for CO2 and H2O.

Comparison of steady shear viscosity by cone and plate, concentric cylinders, and parallel plates with dynamic viscosity r ([Pg.278]

The transport coefficients for a moderately dense gas can be extracted from these results. A comparison of Newton s viscosity law (1.77) from continuum mechanics with (2.687) and of Fourier s law (2.580) with (2.691), approximate values of the transport coefficients (i.e., for the dynamic viscosity and the conductivity) can be determined. The dynamic viscosity, is given by ... 

The viscoelastic characteristics are usually obtained from the results of dynamic experiments in which knowledge of the law of the change in the molecular orientation with variable loads is even more important for the correct interpretation of the results than in the case of steady-state shear flow. The absence of a homogeneous orientation in each cycle can be the cause of the almost constantly observed difference in the values of the complex dynamic viscosity Tj and the related characteristic in the established flow mode in conditions of the comparison of y = co (co is the angular frequency). Generally speaking, despite the qualitative correlation between the dynamic and steady-state characteristics of LC polymers, quantitative coincidence between them is usually... 

Figure 11.8 Comparison of the predictions of the MLD modei (soiid iines) and DEMG model (broken iines) with experimentai data (symbois) for the viscosity, shear stress and first normal stress difference of a 7 wt% soiution of neariy monodisperse polystyrene of molecular weight 2.89 million in tricresylphosphate at 40 °C.The open circles are the dynamic viscosity if oi. The parameter values for the MLD theory are G 5 = 3000 dyn/cm Tj, = 3.06 s, and = 0.13 s. From Pattamaprom and Larson [36].

Fig. 4 Comparison of the dynamic viscosity ( r) ) of a chitosan-TGA/H202 system at pH 6.0 and 37°C. The molar ratios of SH groups oxidizing agent were 1 0.28, 1 0.63, and 1 1.9 and are represented by white, black, and gray bars, respectively. The means SD of three experiments are shown (Adopted from [42])...

Table Z3 A comparison of dynamic viscosity (r ) and specific conductivity (k) for a representative selection of molecular solvents and nonhaloaluminate RTILs...

Figure 4 shows comparisons of the capillary flow curves tested at three temperatures, the oscillatory dynamic viscosity, and the rotational steady shear viscosities tested at 210°C... 

A comparison of the dynamic viscosity of neat PP-g-MA and its nanocomposites with I.30P and Cloisite 15A clay at 150C is presented in Figure 1. The relative viscosity of the nanocomposite with the 1.30P or enhancement over the matrix viscosity is much greater for the 1.30 P. A similar trend can be seen in the storage modulus curves of the nanocomposites as shown in Figure 2. The low frequency plateau is most prominent and higher for the nanocomposite with 1.30P clay. These results are also borne out by the X-Ray diffraction patterns shown in Fig 3 for the two nanocomposites. 

In a current rheological study [296], the galactoxyloglucan from Hymenia courbaril was mixed with starch containing 66% amylose and with waxy corn starch (amylopectin). The gel mixtures showed, under static rheological conditions, an increase in paste viscosity compared to those of the polysaccharides alone. Dynamic rheometry indicated that the interactions resulted in increased thermal stability of the gel formed in comparison to that of the starch alone. 

Predictions on the effectiveness of a fluid loss additive formulation can be made on a laboratory scale by characterizing the properties of the filter-cake formed by appropriate experiments. Most of the fluids containing fluid loss additives are thixotropic. Therefore the apparent viscosity will change when a shear stress in a vertical direction is applied, as is very normal in a circulating drilling fluid. For this reason, the results from static filtering experiments are expected to be different in comparison with dynamic experiments. 

The dynamic process of bubble collapse has been observed by Lauter-born and others by ultrahigh speed photography (105 frames/second) of laser generated cavitation (41). As seen in Fig. 4, the comparison between theory and experiment is remarkably good. These results were obtained in silicone oil, whose high viscosity is responsible for the spherical rebound of the collapsed cavities. The agreement between theoretical predictions and the experimental observations of bubble radius as a function of time are particularly striking. 

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